US20010007431A1 - Low current redundancy anti-fuse method and apparatus - Google Patents

Low current redundancy anti-fuse method and apparatus Download PDF

Info

Publication number
US20010007431A1
US20010007431A1 US09/794,685 US79468501A US2001007431A1 US 20010007431 A1 US20010007431 A1 US 20010007431A1 US 79468501 A US79468501 A US 79468501A US 2001007431 A1 US2001007431 A1 US 2001007431A1
Authority
US
United States
Prior art keywords
fuse
integrated circuit
circuit
state
programmed
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
US09/794,685
Other versions
US6456149B2 (en
Inventor
Douglas Cutter
Kurt Beigel
Fan Ho
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
US Bank NA
Original Assignee
Micron Technology Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Micron Technology Inc filed Critical Micron Technology Inc
Priority to US09/794,685 priority Critical patent/US6456149B2/en
Publication of US20010007431A1 publication Critical patent/US20010007431A1/en
Application granted granted Critical
Publication of US6456149B2 publication Critical patent/US6456149B2/en
Assigned to U.S. BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT reassignment U.S. BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: MICRON TECHNOLOGY, INC.
Assigned to MORGAN STANLEY SENIOR FUNDING, INC., AS COLLATERAL AGENT reassignment MORGAN STANLEY SENIOR FUNDING, INC., AS COLLATERAL AGENT PATENT SECURITY AGREEMENT Assignors: MICRON TECHNOLOGY, INC.
Anticipated expiration legal-status Critical
Assigned to U.S. BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT reassignment U.S. BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT CORRECTIVE ASSIGNMENT TO CORRECT THE REPLACE ERRONEOUSLY FILED PATENT #7358718 WITH THE CORRECT PATENT #7358178 PREVIOUSLY RECORDED ON REEL 038669 FRAME 0001. ASSIGNOR(S) HEREBY CONFIRMS THE SECURITY INTEREST. Assignors: MICRON TECHNOLOGY, INC.
Assigned to MICRON TECHNOLOGY, INC. reassignment MICRON TECHNOLOGY, INC. RELEASE BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: U.S. BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT
Assigned to MICRON TECHNOLOGY, INC. reassignment MICRON TECHNOLOGY, INC. RELEASE BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: MORGAN STANLEY SENIOR FUNDING, INC., AS COLLATERAL AGENT
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11CSTATIC STORES
    • G11C29/00Checking stores for correct operation ; Subsequent repair; Testing stores during standby or offline operation
    • G11C29/70Masking faults in memories by using spares or by reconfiguring
    • G11C29/78Masking faults in memories by using spares or by reconfiguring using programmable devices
    • G11C29/785Masking faults in memories by using spares or by reconfiguring using programmable devices with redundancy programming schemes
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11CSTATIC STORES
    • G11C17/00Read-only memories programmable only once; Semi-permanent stores, e.g. manually-replaceable information cards
    • G11C17/14Read-only memories programmable only once; Semi-permanent stores, e.g. manually-replaceable information cards in which contents are determined by selectively establishing, breaking or modifying connecting links by permanently altering the state of coupling elements, e.g. PROM
    • G11C17/18Auxiliary circuits, e.g. for writing into memory
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11CSTATIC STORES
    • G11C29/00Checking stores for correct operation ; Subsequent repair; Testing stores during standby or offline operation
    • G11C29/70Masking faults in memories by using spares or by reconfiguring
    • G11C29/78Masking faults in memories by using spares or by reconfiguring using programmable devices
    • G11C29/83Masking faults in memories by using spares or by reconfiguring using programmable devices with reduced power consumption

Definitions

  • the present invention relates generally to integrated circuits, and more particularly to fuse-controlled programmable circuits used to replace primary circuit elements with redundant circuit elements in integrated circuits such as memory integrated circuits.
  • DRAMs dynamic random access memories
  • SRAMs static random access memories
  • VRAMs video random access memories
  • EPROMs erasable programmable read only memories
  • Typical integrated memory circuits comprise millions of equivalent memory cells arranged in arrays of addressable rows and columns. The rows and columns of memory cells are the primary circuit elements of the integrated memory circuit.
  • replacing a defective circuit element typically entails blowing fuses or anti-fuses in fuse-controlled programmable circuits to “program” a redundant circuit element to respond to the address of the defective primary circuit element. This process is very effective for permanently replacing defective primary circuit elements.
  • a particular memory cell is selected by first providing a unique row address of the row in which the particular memory cell is located and subsequently providing a unique column address of the column in which the particular memory cell is located.
  • Redundancy circuitry must recognize the address of the effective primary circuit element and reroute all signals to the redundant circuit element when the address to the defective primary circuit element is presented by the user. Therefore, a number of fuses or anti-fuses are associated with each redundant circuit element. The possible combinations of blown and unblown fuses corresponding to each redundant circuit element represent unique addresses of all primary circuit elements for which a corresponding redundant circuit element may be substituted.
  • any defective primary circuit elements are identified.
  • a suitable redundant circuit element is selected, and the corresponding fuses or anti-fuses are blown in a predetermined order to represent the address of the defective primary circuit element to be replaced.
  • each address provided to the DRAM must be compared to the corresponding fuses or anti-fuses to determine if a redundant match is present. Whenever the redundant match is detected, the primary circuit element is suppressed and the redundant circuit element is activated to perform the required function.
  • fuses or anti-fuses can be used in the fuse-controlled programmable circuits.
  • an anti-fuse is typically a nitrite capacitor which is essentially a normal memory array cell used as a blowable capacitor.
  • the anti-fuse is typically a one-time blowable or programmable element which remains shorted when the circuit is powered down and re-powered up.
  • One problem with an anti-fuse controlled programmable circuit is that once the fuse has been blown (or shorted), current is drawn through the anti-fuse. As more programmable anti-fuse circuits are disposed in an integrated circuit, and programmed by blowing the anti-fuses, the cumulative current drawn through the anti-fuses can be significant and can possibly affect the operation of the integrated circuit.
  • the length of the pull-up “long-L” p-channel transistor can be increased to decrease the current drawn between the power rail and ground, the increased length results in even more area being occupied by the long-L p-channel transistors of the anti-fuse controlled programmable circuits.
  • the present invention provides a programmable circuit coupled to a first power supply and a second power supply for providing a programmed signal in an integrated circuit.
  • the programmable circuit includes a first node.
  • the state of the programmed signal is based on the state of the first node.
  • a first anti-fuse has a programmed state and an unprogrammed state and couples the first node to the first power supply when in the programmed state and decouples the first node from the first power supply when in the unprogrammed state.
  • a second anti-fuse has a programmed state and an unprogrammed state and couples the first node to the second power supply when in the programmed state and decouples the first node from the second power supply when in the unprogrammed state.
  • the first anti-fuse and the second anti-fuse each include a first terminal and a second terminal.
  • the first terminals of the first and second anti-fuses are coupled to the first node.
  • a first programming bus carries a sufficient voltage to short the first anti-fuse.
  • a first switch is coupled to the second terminal of the first anti-fuse and couples the second terminal of the first anti-fuse to the first power supply during normal operation of the integrated circuit and couples the second terminal of the first anti-fuse to the first programing bus during a first programming operation of the integrated circuit for programming the first anti-fuse.
  • a second programming bus carries a sufficient voltage to short the second anti-fuse.
  • a second switch is coupled to the second terminal of the second anti-fuse and couples the second terminal of the second anti-fuse to the second power supply during normal operation of the integrated circuit and couples the second terminal of the second anti-fuse to the second programing bus during a second programming operation of the integrated circuit for programming the second anti-fuse.
  • the second power supply comprises a ground node and the programmable circuit includes a switch coupled between the ground node and the first node.
  • the switch is responsive to at least one programming control signal received by the programmable circuit.
  • the switch is closed to couple the first node to the ground node during a programming operation of the integrated circuit and open during normal operations of the integrated circuit.
  • the switch preferably is implemented in a transistor.
  • the second power supply comprises a ground node and the programmable circuit includes a switch coupled between the ground node and the first node.
  • the switch is responsive to an enable signal received by the programming circuit.
  • the switch is closed to couple the first node to the ground node based on the enable signal being in a first state.
  • the switch is open based on the enable signal being in a second state.
  • the switch preferably is implemented in a transistor.
  • the integrated circuit includes primary circuit elements, such as memory cells of a memory integrated circuit.
  • the integrated circuit also includes at least one redundant circuit element. A selected one of the primary circuit elements is replaceable by the at least one redundant circuit element based on the state of the programmed signal.
  • the programmable circuit according to the present invention includes two anti-fuses, with only one of the two anti-fuses being programmed, instead of a single anti-fuse to produce two states on the programmed signal.
  • no resistive short exists between the power supply and ground after the programming the programmable circuit, because only one of the two anti-fuses is programmed which leaves the unprogrammed anti-fuse open. This substantially decreases or substantially eliminates current drawn through a blown or shorted anti-fuse to ground. This also eliminates the need for long-L p-channel transistors to pull up the anti-fuses, which provides a substantial area saving in the integrated circuit employing numerous programmable circuits according to the present invention.
  • FIGS 1 A- 1 C are illustrations of a suitable configuration of a 64 megabit DRAM having redundancy circuitry according to the present invention.
  • FIG. 2 is a block diagram of match anti-fuse bank circuit according to the present invention, which is employed in the DRAM partially illustrated in FIGS. 1 A- 1 C.
  • FIG. 3 is a more detailed block diagram of the match anti-fuse bank of circuit of FIG. 2.
  • FIG. 4 is a schematic diagram of a single anti-fuse controlled programmable circuit employed in the match anti-fuse bank of FIG. 2 for generating an enable bit.
  • FIG. 5 is a schematic diagram of a dual anti-fuse controlled programmable circuit employed in the match anti-fuse bank of FIG. 2.
  • DRAM dynamic random access memory
  • SRAMs static random access memories
  • VRAMs video random access memories
  • EPROMs erasable programmable read only memories
  • the present invention can be applied to any electronic integrated circuit having primary and redundant circuitry comprising separately addressable circuit elements.
  • FIG. 1A Addressable memory cells of a 64 megabit DRAM according to the present invention are illustrated generally at 20 in FIG. 1A.
  • the 64 megabit DRAM according to the present invention is similar in many respects to conventional DRAMs, such as those commercially available from Micron Technology, Inc. of Boise, Id. For clarity, only a portion of the well known circuitry of the DRAM is described herein, while the new circuitry of the DRAM of the present invention is described in detail herein.
  • the 64 megabit DRAM includes eight sections 22 .
  • each section 22 includes eight sub-sections or arrays 24 .
  • each array 24 includes one megabit of memory cells arranged in 512 addressable primary rows or circuit elements 26 and 2048 addressable primary columns or circuit elements 28 .
  • each array 24 includes four addressable redundant rows or circuit elements 30 and four addressable redundant columns or circuit elements 32 .
  • Four redundant rows and four redundant columns are shown in FIG. 1C for illustrative purposes only, and the exact number of redundant circuit elements included in a DRAM or other integrated circuit according to the present invention is determined based on known design criteria.
  • Each primary row 26 is uniquely addressable. Thus, any one of the primary rows 26 in the DRAM can be addressed using twelve address lines (i.e., nine address lines corresponding to the 512 primary rows 26 and three address lines corresponding to the eight sections 22 ). If testing procedures indicate that a primary row is defective, a redundant row 30 is “programmed” to replace the defective primary row 26 . This is accomplished by programming a redundant row 30 to respond to the address corresponding to the defective primary row 26 .
  • Each match anti-fuse bank circuit 40 evaluates the address signal 42 and activates a match signal, indicated at 44 , if the row address value of address signal 42 corresponds to the address of a defective primary row 26 which the match anti-fuse bank circuit is programmed to replace. Similarly, each match anti-fuse bank circuit 40 activates the match signal 44 if the column address value of address signal 42 corresponds to the address of a defective primary column 28 which the match anti-fuse bank circuit is programmed to replace.
  • the match signal 44 when activated by the corresponding match anti-fuse bank circuit 40 , causes the associated redundant row 30 or the associated redundant column 32 to be accessed.
  • the activated match signal 44 also disables the associated defective primary row 26 or the associated primary column 28 such that the associated defective primary row or column cannot respond to the address signal 42 .
  • match anti-fuse bank circuit 40 comprises ‘i’ dual anti-fuse controlled programmable circuits 50 to correspond to address bits A 0 * through Ai* received from address signal 42 .
  • Match anti-fuse bank 40 also comprises a single anti-fuse controlled programmable circuit 52 to receive a high-order address bit A i+1 * from address signal 42 .
  • a fuse program (FP*) signal derived from the row address strobe (RAS) signal to the DRAM is provided on a line 64 to single anti-fuse controlled programmable circuit 52 .
  • a fuse bank select (FBSEL*) signal is provided on a line 66 to single anti-fuse controlled programmable circuit 52 and to all dual anti-fuse controlled programmable circuits 50 on a line 66 .
  • FBSEL* is typically a high-order address bit which is low when the particular fuse bank is selected for programming.
  • a test mode signal (PRG*) which indicates that anti-fuses can be programmed when low, is provided on a line 68 to single anti-fuse controlled programmable circuit 52 and to all dual anti-fuse controlled programmable circuits 50 .
  • Single anti-fuse controlled programmable circuit 52 provides a F* signal on a line 54 .
  • the F* signal on line 54 is provided to one input of a two input NOR gate 56 .
  • An inverter 57 inverts the PRG* signal to produce a PRG signal on a line 69 .
  • the PRG signal on line 69 is provided to the other input of NOR gate 56 .
  • NOR gate 56 provides an EN* (enable) signal on a line 58 to all of the dual anti-fuse controlled programmable circuits 50 . When the EN* signal is low, the dual anti-fuse controlled programmable circuits 50 are enabled for programming.
  • Single anti-fuse controlled programmable circuit 52 is illustrated in more detail in schematic diagram form in FIG. 4.
  • the layout of single anti-fuse controlled programmable circuit 52 is similar to conventional anti-fuse controlled programmable circuits for the individual address bits of prior art match anti-fuse bank circuits.
  • Single anti-fuse controlled programmable circuit 52 is used to generate the EN* signal on line 58 in the match anti-fuse bank circuit 40 according to the present invention.
  • a three input NOR gate 80 receives the PRG* signal on line 68 , the FBSEL* signal on line 66 , and the Ai+1 * signal on line 42 (i+1) and activates an output line 82 when all three input signals are a low-logic level.
  • the output of NOR gate 80 on line 82 is provided to the gate of an n-channel transistor 84 .
  • the source of n-channel transistor 84 is coupled to a ground node.
  • the drain of n-channel transistor 84 is coupled to a node 86 .
  • An anti-fuse 88 has one of its terminals coupled to node 86 and its other terminal coupled to a switch 90 .
  • Switch 90 switches between a ground node and the CGND bus 70 .
  • the switch 90 switches to the CGND bus 70 and during normal operations, switch 90 switches to the ground node.
  • one terminal of anti-fuse 88 is coupled to a ground level at node 86 and the other terminal is coupled to the CGND bus 70 .
  • a high voltage such as 10 volts, or the voltage needed to exceed the breakdown voltage of anti-fuse 88 to permanently short anti-fuse 88 , is provided on the CGND bus 70 .
  • Node 86 is also coupled to the input of an inverter 92 which supplies the F* signal on line 54 from single anti-fuse controlled programmable circuit 52 .
  • the F* signal is coupled to the gate of a p-channel transistor 94 .
  • the source of p-channel transistor 94 is coupled to the Vcc power supply.
  • the FP* signal on line 64 is provided to the gate of a p-channel transistor 96 .
  • the source of p-channel transistor 96 is coupled to the Vcc power supply.
  • the drains of p-channel transistors 94 and 96 are coupled together and coupled to the source of a long-L p-channel pull-up transistor 98 .
  • the gate of long-L p-channel pull-up transistor 98 is coupled to ground.
  • the drain of long-L p-channel pull-up transistor 98 is coupled to node 86 .
  • Dual anti-fuse controlled programmable circuit 50 is illustrated in more detail in schematic diagram form in FIG. 5.
  • a NOR gate 100 receives the PRG* signal on line 68 , the FBSEL* signal on line 66 , and an individual address bit indicated by Am* on the 42 (m) line.
  • NOR gate 100 activates an output line 102 when all three inputs are low.
  • the output of NOR gate 100 on line 102 is coupled to the gate of an n-channel transistor 104 .
  • the source of n-channel transistor 104 is coupled to ground.
  • the drain of n-channel transistor 104 is coupled to a node 106 .
  • line 102 becomes high to turn transistor 104 on.
  • node 106 is effectively coupled to the ground node.
  • An anti-fuse 112 has one of its terminals coupled to node 106 and its other terminal coupled to a switch 114 .
  • Switch 114 switches between a ground node and the CVCC bus 72 .
  • the switch 114 switches to the CVCC bus 72 and during normal operations, switch 114 switches to the Vcc power supply or a DVC2 power supply.
  • one terminal of anti-fuse 112 is coupled to a ground level at node 106 and the other terminal is coupled to the CVCC bus 72 .
  • a high voltage such as 10 volts, or the voltage needed to exceed the breakdown voltage of anti-fuse 112 to permanently short anti-fuse 112 , is provided on the CVCC bus 72 .
  • one terminal of anti-fuse 112 is coupled to DVC2, having a Vcc/2 level, instead of the full Vcc power supply.
  • the Vcc/2 potential across anti-fuse 112 reduces or substantially eliminates potential reliability problems that can result from having a full Vcc potential across anti-fuse 112 .
  • the output inverter 116 needs to be skewed to operate at a reduced input swing voltage.
  • n-channel transistor 118 is turned off to enable the circuit to operate appropriately as described below.
  • node 106 is brought to Vcc or DVC2 (a high-logic level). The high-logic level is inverted by inverter 116 to provide a low or zero output on the F* signal on line 60 .
  • node 106 is tied to the ground node (a low-logic level). Inverter 116 inverts the low-logic level to provide a high or one output on the F* signal on line 60 .
  • dual anti-fuse controlled programmable circuit 50 is employed in match fuse bank 40 illustrated in FIGS. 2 and 3 for programming to respond to specific values of the address signal 42 for replacing primary circuit elements, such as row or columns of a DRAM, with redundant circuit elements.
  • Dual anti-fuse controlled programmable circuit 50 is, however, alternatively embodied in a variety of circuit applications where a programming feature is required.
  • multiple dual anti-fuse controlled programmable circuits 50 are employed to generate a fuse identification (ID) for an integrated circuit.
  • the fuse ID is a pattern of binary digits which uniquely identify the integrated circuit chip and can be decoded after the chip is packaged or integrated onto a circuit board.
  • Dual anti-fuse controlled programmable circuit 50 is alternatively embodied in another form of the present invention to select a mode of operation in the integrated circuit.
  • the amount of refresh available in a memory integrated circuit can be controlled with multiple dual anti-fuse controlled programmable circuits 50 , such as by selecting between 4 K rows or 8 K rows in a 64 Meg DRAM.
  • Another mode of operation application is to utilize dual anti-fuse programmable circuit 50 for slowing down or speeding up the integrated circuit.
  • dual anti-fuse controlled programmable circuits 50 is employed to select either a fast page mode for a memory integrated circuit or an extended data out (EDO) mode for the memory integrated circuit.
  • EEO extended data out
  • the dual anti-fuse structure of dual anti-fuse controlled programmable circuit 50 of the present invention eliminates the need for a long-L p-channel pull-up transistor, such as long-L p-channel pull-up transistor 98 of single anti-fuse programmable circuit 52 .
  • the standby current resulting in conventional anti-fuse controlled programmable circuits, such as single anti-fuse controlled programmable circuit 52 resulting when the single anti-fuse is programmed or shorted to cause a resistive connection between the Vcc power supply and ground, is substantially eliminated with dual anti-fuse controlled programmable circuit 50 .
  • the standby current no longer exists because one of anti-fuses 108 or 112 remains open so that there is substantially no connection created between the Vcc power supply and ground.
  • the dual anti-fuse controlled programmable circuit 50 of the present invention occupies significantly less space in an integrated circuit than the conventional type single anti-fuse controlled programmable circuit 52 . Assuming one n-channel transistor occupies approximately the same space as one p-channel transistor, there is the equivalent of one less normal p-channel transistor in the dual anti-fuse controlled programmable circuit 50 , because n-channel transistor 118 replaces the two p-channel transistors 96 and 94 . Most significantly, the long-L p-channel pull-up transistor 98 is completely eliminated in the dual anti-fuse controlled programmable circuit 50 .
  • the dual anti-fuse controlled programmable circuit 50 adds one anti-fuse over the single anti-fuse controlled programmable circuit 52 , the additional space occupied by the additional anti-fuse is much less than the space needed for one normal p-channel transistor and one long-L p-channel transistor. Thus, the net effect is a significant savings in die area when the dual anti-fuse controlled circuits of the present invention are employed in an integrated circuit, such as in match anti-fuse bank circuit 40 of FIG. 3.
  • the match anti-fuse bank circuit according to the present invention utilizing the dual anti-fuse controlled programmable circuit 50 according to the present invention operates with only one of the dual anti-fuses being programmed. Therefore, no resistive short between the Vcc power supply and ground is established, which substantially decreases or eliminates current drawn through a blown or shorted anti-fuse to ground. This also eliminates the need for long-L p-channel transistors to pull up the anti-fuses, which provides a substantial area saving in the integrated circuit employing dual anti-fuse programmable circuits according to the present invention.

Abstract

A programmable circuit includes a first node and provides a programmed signal based on the state of the first node. A first anti-fuse has a programmed state and an unprogrammed state and couples the first node to a first power supply when in the programmed state and decouples the first node from the first power supply when in the unprogrammed state. A second anti-fuse has a programmed state and an unprogrammed state and couples the first node to a second power supply when in the programmed state and decouples the first node from the second power supply when in the unprogrammed state. The state of the programmed signal can be used to replace a primary circuit element of an integrated circuit with a redundant circuit element.

Description

    THE FIELD OF THE INVENTION
  • The present invention relates generally to integrated circuits, and more particularly to fuse-controlled programmable circuits used to replace primary circuit elements with redundant circuit elements in integrated circuits such as memory integrated circuits. [0001]
  • BACKGROUND OF THE INVENTION
  • Technological advances have permitted semiconductor integrated circuits to comprise significantly more circuit elements in a given silicon area. Reducing and eliminating defects in the circuit elements has, however, become increasingly more difficult with the increased number of circuit elements. To achieve higher population capacities, circuit designers strive to reduce the size of the individual circuit elements to maximize available die real estate. The reduced size makes these circuit elements increasingly susceptible to defects caused by material impurities during fabrication. Nevertheless, the defects are identifiable upon completion of the integrated circuit fabrication by testing procedures, either at the semiconductor chip level or after complete packaging. Scrapping or discarding defective integrated circuits when defects are identified is economically undesirable, particularly if only a small number of circuit elements are actually defective. [0002]
  • Relying on zero defects in the fabrication of integrated circuits is an unrealistic option. Therefore, redundant circuit elements are provided on integrated circuits to reduce the number of scrapped integrated circuits. If a primary circuit element is determined to be defective, a redundant circuit element is substituted for the defective primary circuit element. Substantial reductions in scrap are achieved by using redundant circuit elements without substantially increasing the cost of the integrated circuit. [0003]
  • One type of integrated circuit device which uses redundant circuit elements is integrated memory circuits, such as dynamic random access memories (DRAMs), static random access memories (SRAMs), video random access memories (VRAMs), and erasable programmable read only memories (EPROMs). Typical integrated memory circuits comprise millions of equivalent memory cells arranged in arrays of addressable rows and columns. The rows and columns of memory cells are the primary circuit elements of the integrated memory circuit. By providing redundant circuit elements, either as rows or columns, defective primary rows, columns, or individual bits can be replaced. [0004]
  • Because the individual primary circuit elements (rows or columns) of an integrated memory circuit are separately addressable, replacing a defective circuit element typically entails blowing fuses or anti-fuses in fuse-controlled programmable circuits to “program” a redundant circuit element to respond to the address of the defective primary circuit element. This process is very effective for permanently replacing defective primary circuit elements. [0005]
  • In the case of DRAMs, for example, a particular memory cell is selected by first providing a unique row address of the row in which the particular memory cell is located and subsequently providing a unique column address of the column in which the particular memory cell is located. Redundancy circuitry must recognize the address of the effective primary circuit element and reroute all signals to the redundant circuit element when the address to the defective primary circuit element is presented by the user. Therefore, a number of fuses or anti-fuses are associated with each redundant circuit element. The possible combinations of blown and unblown fuses corresponding to each redundant circuit element represent unique addresses of all primary circuit elements for which a corresponding redundant circuit element may be substituted. [0006]
  • During testing of the DRAM, or other integrated circuit, at the factory, any defective primary circuit elements are identified. A suitable redundant circuit element is selected, and the corresponding fuses or anti-fuses are blown in a predetermined order to represent the address of the defective primary circuit element to be replaced. When using the DRAM, each address provided to the DRAM must be compared to the corresponding fuses or anti-fuses to determine if a redundant match is present. Whenever the redundant match is detected, the primary circuit element is suppressed and the redundant circuit element is activated to perform the required function. [0007]
  • As mentioned above, fuses or anti-fuses can be used in the fuse-controlled programmable circuits. In a DRAM, an anti-fuse is typically a nitrite capacitor which is essentially a normal memory array cell used as a blowable capacitor. Thus, no extra process steps are required in the fabrication of a DRAM to produce an anti-fuse. Unlike the fuse which is open after being blown, the anti-fuse is typically a one-time blowable or programmable element which remains shorted when the circuit is powered down and re-powered up. One problem with an anti-fuse controlled programmable circuit is that once the fuse has been blown (or shorted), current is drawn through the anti-fuse. As more programmable anti-fuse circuits are disposed in an integrated circuit, and programmed by blowing the anti-fuses, the cumulative current drawn through the anti-fuses can be significant and can possibly affect the operation of the integrated circuit. [0008]
  • Conventional anti-fuse controlled programmable circuits use long-L p-channel transistors to pull up anti-fuses. The long-L p-channel transistor effectively decreases the amount of current drawn through a blown (shorted) anti-fuse to ground. Nevertheless, the resulting standby and operating current due to a resistor short between the power rail and ground when anti-fuses have been programmed is still somewhat significant. Moreover, the long-L p-channel transistor of existing anti-fuse structures occupies significant real estate in the integrated circuit. Thus, although the length of the pull-up “long-L” p-channel transistor can be increased to decrease the current drawn between the power rail and ground, the increased length results in even more area being occupied by the long-L p-channel transistors of the anti-fuse controlled programmable circuits. [0009]
  • Therefore, there is a need in the art for an anti-fuse controlled programmable circuit which substantially eliminates or significantly reduces the resulting standby current from blown or programmed anti-fuses. Moreover, there is a need for an improved anti-fuse controlled programmable circuit which occupies less area in the integrated circuit [0010]
  • SUMMARY OF THE INVENTION
  • The present invention provides a programmable circuit coupled to a first power supply and a second power supply for providing a programmed signal in an integrated circuit. The programmable circuit includes a first node. The state of the programmed signal is based on the state of the first node. A first anti-fuse has a programmed state and an unprogrammed state and couples the first node to the first power supply when in the programmed state and decouples the first node from the first power supply when in the unprogrammed state. A second anti-fuse has a programmed state and an unprogrammed state and couples the first node to the second power supply when in the programmed state and decouples the first node from the second power supply when in the unprogrammed state. [0011]
  • In one embodiment of the programmable circuit according to the present invention, the first anti-fuse and the second anti-fuse each include a first terminal and a second terminal. The first terminals of the first and second anti-fuses are coupled to the first node. A first programming bus carries a sufficient voltage to short the first anti-fuse. A first switch is coupled to the second terminal of the first anti-fuse and couples the second terminal of the first anti-fuse to the first power supply during normal operation of the integrated circuit and couples the second terminal of the first anti-fuse to the first programing bus during a first programming operation of the integrated circuit for programming the first anti-fuse. A second programming bus carries a sufficient voltage to short the second anti-fuse. A second switch is coupled to the second terminal of the second anti-fuse and couples the second terminal of the second anti-fuse to the second power supply during normal operation of the integrated circuit and couples the second terminal of the second anti-fuse to the second programing bus during a second programming operation of the integrated circuit for programming the second anti-fuse. [0012]
  • In one embodiment of the present invention the second power supply comprises a ground node and the programmable circuit includes a switch coupled between the ground node and the first node. The switch is responsive to at least one programming control signal received by the programmable circuit. The switch is closed to couple the first node to the ground node during a programming operation of the integrated circuit and open during normal operations of the integrated circuit. The switch preferably is implemented in a transistor. [0013]
  • In one embodiment of the present invention the second power supply comprises a ground node and the programmable circuit includes a switch coupled between the ground node and the first node. The switch is responsive to an enable signal received by the programming circuit. The switch is closed to couple the first node to the ground node based on the enable signal being in a first state. The switch is open based on the enable signal being in a second state. The switch preferably is implemented in a transistor. [0014]
  • In one application of the present invention the integrated circuit includes primary circuit elements, such as memory cells of a memory integrated circuit. The integrated circuit also includes at least one redundant circuit element. A selected one of the primary circuit elements is replaceable by the at least one redundant circuit element based on the state of the programmed signal. [0015]
  • The programmable circuit according to the present invention includes two anti-fuses, with only one of the two anti-fuses being programmed, instead of a single anti-fuse to produce two states on the programmed signal. In the programmable circuit of the present invention, no resistive short exists between the power supply and ground after the programming the programmable circuit, because only one of the two anti-fuses is programmed which leaves the unprogrammed anti-fuse open. This substantially decreases or substantially eliminates current drawn through a blown or shorted anti-fuse to ground. This also eliminates the need for long-L p-channel transistors to pull up the anti-fuses, which provides a substantial area saving in the integrated circuit employing numerous programmable circuits according to the present invention. [0016]
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIGS [0017] 1A-1C are illustrations of a suitable configuration of a 64 megabit DRAM having redundancy circuitry according to the present invention.
  • FIG. 2 is a block diagram of match anti-fuse bank circuit according to the present invention, which is employed in the DRAM partially illustrated in FIGS. [0018] 1A-1C.
  • FIG. 3 is a more detailed block diagram of the match anti-fuse bank of circuit of FIG. 2. [0019]
  • FIG. 4 is a schematic diagram of a single anti-fuse controlled programmable circuit employed in the match anti-fuse bank of FIG. 2 for generating an enable bit. [0020]
  • FIG. 5 is a schematic diagram of a dual anti-fuse controlled programmable circuit employed in the match anti-fuse bank of FIG. 2. [0021]
  • DESCRIPTION OF THE PREFERRED EMBODIMENTS
  • In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. [0022]
  • The following described embodiments of the present invention are described as applied to a dynamic random access memory (DRAM). The present invention is not limited to DRAMs, as the present invention is equally applied to other memory devices such as static random access memories (SRAMs), video random access memories (VRAMs), and erasable programmable read only memories (EPROMs). In fact, the present invention can be applied to any electronic integrated circuit having primary and redundant circuitry comprising separately addressable circuit elements. [0023]
  • Example DRAM Configuration
  • Addressable memory cells of a 64 megabit DRAM according to the present invention are illustrated generally at [0024] 20 in FIG. 1A. The 64 megabit DRAM according to the present invention is similar in many respects to conventional DRAMs, such as those commercially available from Micron Technology, Inc. of Boise, Id. For clarity, only a portion of the well known circuitry of the DRAM is described herein, while the new circuitry of the DRAM of the present invention is described in detail herein. As illustrated in FIG. 1A, the 64 megabit DRAM includes eight sections 22. As illustrated in FIG. 1B, each section 22 includes eight sub-sections or arrays 24. As illustrated in FIG. 1C, each array 24 includes one megabit of memory cells arranged in 512 addressable primary rows or circuit elements 26 and 2048 addressable primary columns or circuit elements 28.
  • In addition, in the embodiment of the 64 megabit DRAM according to the present invention illustrated in FIGS. [0025] 1A-1C, each array 24 includes four addressable redundant rows or circuit elements 30 and four addressable redundant columns or circuit elements 32. Four redundant rows and four redundant columns are shown in FIG. 1C for illustrative purposes only, and the exact number of redundant circuit elements included in a DRAM or other integrated circuit according to the present invention is determined based on known design criteria.
  • Each [0026] primary row 26 is uniquely addressable. Thus, any one of the primary rows 26 in the DRAM can be addressed using twelve address lines (i.e., nine address lines corresponding to the 512 primary rows 26 and three address lines corresponding to the eight sections 22). If testing procedures indicate that a primary row is defective, a redundant row 30 is “programmed” to replace the defective primary row 26. This is accomplished by programming a redundant row 30 to respond to the address corresponding to the defective primary row 26.
  • Each [0027] primary column 28 is also uniquely addressable. Thus, anyone of the primary columns 28 in the DRAM can be addressed using fourteen address lines (i.e., eleven address lines corresponding to the 2048 primary columns 28 and three address lines corresponding to the eight arrays 24). If testing procedures indicate that a primary column is defective, a redundant column 32 is “programed” to replace the defective primary column 28. This is accomplished by programming a redundant column 32 to respond to the address corresponding to the defective primary column 28.
  • Match Anti-Fuse Bank Circuit
  • Referring to FIG. 2, each of the four [0028] redundant rows 30 and each of the four redundant columns 32 of each array 24 includes a corresponding multi-bit address/anti-fuse comparison circuit module or match anti-fuse bank circuit 40 according to the present invention. Each match anti-fuse bank circuit 40 is capable of receiving a multi-bit address signal, indicated at 42, in the form of a pre-decoded signal or a non-predecoded signal depending on the embodiment of the match anti-fuse bank. The address signal 42 is used to address the primary rows 26 at one time and the primary columns at a subsequent time based on the state of selected command input signals to the DRAM. Each match anti-fuse bank circuit 40 is selectively programmable to respond to a specific value of the address signal 42. Each match anti-fuse bank circuit 40 evaluates the address signal 42 and activates a match signal, indicated at 44, if the row address value of address signal 42 corresponds to the address of a defective primary row 26 which the match anti-fuse bank circuit is programmed to replace. Similarly, each match anti-fuse bank circuit 40 activates the match signal 44 if the column address value of address signal 42 corresponds to the address of a defective primary column 28 which the match anti-fuse bank circuit is programmed to replace.
  • The [0029] match signal 44, when activated by the corresponding match anti-fuse bank circuit 40, causes the associated redundant row 30 or the associated redundant column 32 to be accessed. The activated match signal 44 also disables the associated defective primary row 26 or the associated primary column 28 such that the associated defective primary row or column cannot respond to the address signal 42.
  • A more detailed schematic diagram of match [0030] anti-fuse bank circuit 40 is illustrated in FIG. 3. As illustrated in FIG. 3, match anti-fuse bank 40 comprises ‘i’ dual anti-fuse controlled programmable circuits 50 to correspond to address bits A0* through Ai* received from address signal 42. Match anti-fuse bank 40 also comprises a single anti-fuse controlled programmable circuit 52 to receive a high-order address bit Ai+1* from address signal 42.
  • A fuse program (FP*) signal derived from the row address strobe (RAS) signal to the DRAM is provided on a [0031] line 64 to single anti-fuse controlled programmable circuit 52. A fuse bank select (FBSEL*) signal is provided on a line 66 to single anti-fuse controlled programmable circuit 52 and to all dual anti-fuse controlled programmable circuits 50 on a line 66. FBSEL* is typically a high-order address bit which is low when the particular fuse bank is selected for programming. A test mode signal (PRG*) which indicates that anti-fuses can be programmed when low, is provided on a line 68 to single anti-fuse controlled programmable circuit 52 and to all dual anti-fuse controlled programmable circuits 50.
  • Single anti-fuse controlled [0032] programmable circuit 52 provides a F* signal on a line 54. The F* signal on line 54 is provided to one input of a two input NOR gate 56. An inverter 57 inverts the PRG* signal to produce a PRG signal on a line 69. The PRG signal on line 69 is provided to the other input of NOR gate 56. NOR gate 56 provides an EN* (enable) signal on a line 58 to all of the dual anti-fuse controlled programmable circuits 50. When the EN* signal is low, the dual anti-fuse controlled programmable circuits 50 are enabled for programming. Each of the dual anti-fuse controlled programmable circuits 50 provide a corresponding F* signal on a corresponding line 60 which are all provided to a compare logic circuit 62 along with the F* signal on line 54 from single anti-fuse controlled programmable circuit 52. In addition, the EN* signal on line 58 and address inputs A<0:(i+1)> on line 42 are also provided to compare logic circuit 62. Compare logic circuit 62 provides the match signal indicated at 44, which is activated if every single address input A0-Ai+1 matches the corresponding state of the corresponding anti-fuses in the anti-fuse controlled programmable circuits 50 and 52 as indicated by the F* signals.
  • A program/[0033] ground CGND bus 70 is provided to single anti-fuse controlled programmable circuit 52 and to all dual anti-fuse controlled circuits 50. In addition, a program/power CVCC bus 72 is provided to all dual anti-fuse controlled programmable circuits 50. The operation of the CGND bus 70 and the CVCC bus 72 are described below in reference to FIGS. 4 and 5.
  • Single Anti-Fuse Controlled Programmable Circuit for Enable Bit
  • Single anti-fuse controlled [0034] programmable circuit 52 is illustrated in more detail in schematic diagram form in FIG. 4. The layout of single anti-fuse controlled programmable circuit 52, as illustrated in FIG. 4, is similar to conventional anti-fuse controlled programmable circuits for the individual address bits of prior art match anti-fuse bank circuits. Single anti-fuse controlled programmable circuit 52, however, is used to generate the EN* signal on line 58 in the match anti-fuse bank circuit 40 according to the present invention.
  • As illustrated in FIG. 4, a three input NOR [0035] gate 80 receives the PRG* signal on line 68, the FBSEL* signal on line 66, and the Ai+1 * signal on line 42 (i+1) and activates an output line 82 when all three input signals are a low-logic level. The output of NOR gate 80 on line 82 is provided to the gate of an n-channel transistor 84. The source of n-channel transistor 84 is coupled to a ground node. The drain of n-channel transistor 84 is coupled to a node 86. With the PRG*, FBSEL* and the Am* signals all low, line 82 becomes high to turn transistor 84 on. With transistor 84 on, node 86 is effectively coupled to the ground node.
  • An anti-fuse [0036] 88 has one of its terminals coupled to node 86 and its other terminal coupled to a switch 90. Switch 90 switches between a ground node and the CGND bus 70. During programming, the switch 90 switches to the CGND bus 70 and during normal operations, switch 90 switches to the ground node. In this way, during programming one terminal of anti-fuse 88 is coupled to a ground level at node 86 and the other terminal is coupled to the CGND bus 70. In programing anti-fuse 88, a high voltage such as 10 volts, or the voltage needed to exceed the breakdown voltage of anti-fuse 88 to permanently short anti-fuse 88, is provided on the CGND bus 70.
  • [0037] Node 86 is also coupled to the input of an inverter 92 which supplies the F* signal on line 54 from single anti-fuse controlled programmable circuit 52. The F* signal is coupled to the gate of a p-channel transistor 94. The source of p-channel transistor 94 is coupled to the Vcc power supply. The FP* signal on line 64 is provided to the gate of a p-channel transistor 96. The source of p-channel transistor 96 is coupled to the Vcc power supply. The drains of p- channel transistors 94 and 96 are coupled together and coupled to the source of a long-L p-channel pull-up transistor 98. The gate of long-L p-channel pull-up transistor 98 is coupled to ground. The drain of long-L p-channel pull-up transistor 98 is coupled to node 86.
  • In operation, when anti-fuse [0038] 88 is not programmed (open), node 86 is pulled toward VCC to provide a low or zero output on the F* line 54. Thus, the EN* signal, which is an inverted version of the F* signal on line 54 when the PRG signal on line 69 is low, is at a high level when the “enable” anti-fuse 88 is not blown or programmed. When anti-fuse 88 is programmed (shorted), node 86 is pulled to the ground level, which when inverted by inverter 92, produces a high or one output on the F* line 54. Thus, the EN* signal, which is an inverted version of the F* signal on line 54 when the PRG signal on line 69 is low, is at a low level to enable programming of the dual anti-fuse controlled programmable circuits 50 after “enable” anti-fuse 88 is blown.
  • Dual Anti-Fuse Controlled Progrmmable Circuit
  • Dual anti-fuse controlled [0039] programmable circuit 50 is illustrated in more detail in schematic diagram form in FIG. 5. As illustrated in FIG. 5, a NOR gate 100 receives the PRG* signal on line 68, the FBSEL* signal on line 66, and an individual address bit indicated by Am* on the 42 (m) line. NOR gate 100 activates an output line 102 when all three inputs are low. The output of NOR gate 100 on line 102 is coupled to the gate of an n-channel transistor 104. The source of n-channel transistor 104 is coupled to ground. The drain of n-channel transistor 104 is coupled to a node 106. With the PRG*, FBSEL* and the Am* signals all low, line 102 becomes high to turn transistor 104 on. With transistor 104 on, node 106 is effectively coupled to the ground node.
  • An anti-fuse [0040] 108 has one of its terminals coupled to node 106 and its other terminal coupled to a switch 110. Switch 110 switches between a ground node and the CGND bus 70. During programming, the switch 110 switches to the CGND bus 70 and during normal operations, switch 110 switches to the ground node. In this way, during programming one terminal of anti-fuse 108 is coupled to a ground level at node 106 and the other terminal is coupled to the CGND bus 70. In programming anti-fuse 108, a high voltage such as 10 volts, or the voltage needed to exceed the breakdown voltage of anti-fuse 108 to permanently short anti-fuse 108, is provided on the CGND bus 70.
  • An anti-fuse [0041] 112 has one of its terminals coupled to node 106 and its other terminal coupled to a switch 114. Switch 114 switches between a ground node and the CVCC bus 72. During programming, the switch 114 switches to the CVCC bus 72 and during normal operations, switch 114 switches to the Vcc power supply or a DVC2 power supply. In this way, during programming one terminal of anti-fuse 112 is coupled to a ground level at node 106 and the other terminal is coupled to the CVCC bus 72. In programming anti-fuse 112, a high voltage such as 10 volts, or the voltage needed to exceed the breakdown voltage of anti-fuse 112 to permanently short anti-fuse 112, is provided on the CVCC bus 72.
  • As indicated above, in one embodiment of the present invention, one terminal of [0042] anti-fuse 112 is coupled to DVC2, having a Vcc/2 level, instead of the full Vcc power supply. In this embodiment, the Vcc/2 potential across anti-fuse 112 reduces or substantially eliminates potential reliability problems that can result from having a full Vcc potential across anti-fuse 112. However, with anti-fuse 112 tied to DVC2, or other lower voltage than Vcc, the output inverter 116 needs to be skewed to operate at a reduced input swing voltage.
  • [0043] Node 106 is also coupled to an inverter 116. Inverter 116 inverts the state on node 106 and provides the F* signal on the line 160 for the individual address bit Am*.
  • The EN* signal, as stated above, is high before the enable [0044] fuse 88 of single anti-fuse controlled programmable circuit 52 is programmed. The EN* signal being high prevents inverter 116 from having a floating input at node 106. The EN* signal is provided from line 58 to the gate of an n-channel transistor 118. N-channel transistor 118 has its source coupled to the ground node and its drain coupled to node 106. Thus, when the EN* signal is high, n-channel transistor 118 is turned on to couple node 106 to ground to produce a low input into inverter 116 and a high output on F* line 60. When the EN* signal is brought low with the programming of anti-fuse 88 of single anti-fuse controlled programmable circuit 52, or with the PRG* signal going low to produce a high PRG signal on line 69, n-channel transistor 118 is turned off to enable the circuit to operate appropriately as described below.
  • In operation, when anti-fuse [0045] 108 is not programmed (left open) and anti-fuse 112 is programmed (shorted), node 106 is brought to Vcc or DVC2 (a high-logic level). The high-logic level is inverted by inverter 116 to provide a low or zero output on the F* signal on line 60. When anti-fuse 108 is programmed (shorted) and anti-fuse 112 is not programmed (left open), node 106 is tied to the ground node (a low-logic level). Inverter 116 inverts the low-logic level to provide a high or one output on the F* signal on line 60.
  • By programming one of either anti-fuse [0046] 108 or 112, the user of the DRAM, or other integrated circuit according to the present invention, can select the desired state of the output F* signal of anti-fuse controlled programmable circuit 50. As described above, dual anti-fuse controlled programmable circuit 50 is employed in match fuse bank 40 illustrated in FIGS. 2 and 3 for programming to respond to specific values of the address signal 42 for replacing primary circuit elements, such as row or columns of a DRAM, with redundant circuit elements. Dual anti-fuse controlled programmable circuit 50 is, however, alternatively embodied in a variety of circuit applications where a programming feature is required. For example, multiple dual anti-fuse controlled programmable circuits 50 are employed to generate a fuse identification (ID) for an integrated circuit. The fuse ID is a pattern of binary digits which uniquely identify the integrated circuit chip and can be decoded after the chip is packaged or integrated onto a circuit board.
  • Dual anti-fuse controlled [0047] programmable circuit 50 is alternatively embodied in another form of the present invention to select a mode of operation in the integrated circuit. For example, the amount of refresh available in a memory integrated circuit can be controlled with multiple dual anti-fuse controlled programmable circuits 50, such as by selecting between 4 K rows or 8 K rows in a 64 Meg DRAM. Another mode of operation application is to utilize dual anti-fuse programmable circuit 50 for slowing down or speeding up the integrated circuit. In another mode of operation application dual anti-fuse controlled programmable circuits 50 is employed to select either a fast page mode for a memory integrated circuit or an extended data out (EDO) mode for the memory integrated circuit.
  • In any of its implementations, the dual anti-fuse structure of dual anti-fuse controlled [0048] programmable circuit 50 of the present invention eliminates the need for a long-L p-channel pull-up transistor, such as long-L p-channel pull-up transistor 98 of single anti-fuse programmable circuit 52. In addition, the standby current resulting in conventional anti-fuse controlled programmable circuits, such as single anti-fuse controlled programmable circuit 52, resulting when the single anti-fuse is programmed or shorted to cause a resistive connection between the Vcc power supply and ground, is substantially eliminated with dual anti-fuse controlled programmable circuit 50. The standby current no longer exists because one of anti-fuses 108 or 112 remains open so that there is substantially no connection created between the Vcc power supply and ground.
  • The dual anti-fuse controlled [0049] programmable circuit 50 of the present invention occupies significantly less space in an integrated circuit than the conventional type single anti-fuse controlled programmable circuit 52. Assuming one n-channel transistor occupies approximately the same space as one p-channel transistor, there is the equivalent of one less normal p-channel transistor in the dual anti-fuse controlled programmable circuit 50, because n-channel transistor 118 replaces the two p- channel transistors 96 and 94. Most significantly, the long-L p-channel pull-up transistor 98 is completely eliminated in the dual anti-fuse controlled programmable circuit 50. Although the dual anti-fuse controlled programmable circuit 50 adds one anti-fuse over the single anti-fuse controlled programmable circuit 52, the additional space occupied by the additional anti-fuse is much less than the space needed for one normal p-channel transistor and one long-L p-channel transistor. Thus, the net effect is a significant savings in die area when the dual anti-fuse controlled circuits of the present invention are employed in an integrated circuit, such as in match anti-fuse bank circuit 40 of FIG. 3.
  • Conclusion
  • The match anti-fuse bank circuit according to the present invention utilizing the dual anti-fuse controlled [0050] programmable circuit 50 according to the present invention operates with only one of the dual anti-fuses being programmed. Therefore, no resistive short between the Vcc power supply and ground is established, which substantially decreases or eliminates current drawn through a blown or shorted anti-fuse to ground. This also eliminates the need for long-L p-channel transistors to pull up the anti-fuses, which provides a substantial area saving in the integrated circuit employing dual anti-fuse programmable circuits according to the present invention.
  • Although specific embodiments have been illustrated and described herein for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations calculated to achieve the same purposes may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. Those with skill in the mechanical, electro-mechanical, electrical, and computer arts will readily appreciate that the present invention may be implemented in a very wide variety of embodiments. This application is intended to cover any adaptations or variations of the preferred embodiments discussed herein. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof. [0051]

Claims (35)

What is claimed is:
1. A programmable circuit coupled to a first power supply and a second power supply for providing a programmed signal in an integrated circuit comprising:
a first node, wherein the state of the programmed signal is based on the state of the first node;
a first anti-fuse having a programmed state and an unprogrammed state and coupling the first node to the first power supply when in the programmed state and decoupling the first node from the first power supply when in the unprogrammed state; and
a second anti-fuse having a programmed state and an unprogrammed state and coupling the first node to the second power supply when in the programmed state and decoupling the first node from the second power supply when in the unprogrammed state.
2. The programmable circuit of
claim 1
wherein the first anti-fuse and the second anti-fuse each include a first terminal and a second terminal, and wherein the first terminals of the first and second anti-fuses are coupled to the first node, and wherein the programmable circuit further comprises:
a first programming bus carrying a sufficient voltage to short the first anti-fuse;
a first switch coupled to the second terminal of the first anti-fuse for coupling the second terminal of the first anti-fuse to the first power supply during normal operation of the integrated circuit and coupling the second terminal of the first anti-fuse to the first programing bus during a first programming operation of the integrated circuit for programming the first anti-fuse;
a second programming bus carrying a sufficient voltage to short the second anti-fuse; and
a second switch coupled to the second terminal of the second anti-fuse for coupling the second terminal of the second anti-fuse to the second power supply during normal operation of the integrated circuit and coupling the second terminal of the second anti-fuse to the second programing bus during a second programming operation of the integrated circuit for programming the second anti-fuse.
3. The programmable circuit of
claim 1
further comprising:
a switch coupled between the second power supply and the first node and responsive to at least one programming control signal received by the programmable circuit, wherein the switch is closed to couple the first node to the second power supply during a programming operation of the integrated circuit and open during normal operations of the integrated circuit.
4. The programmable circuit of
claim 3
wherein the switch comprises a transistor.
5. The programmable circuit of
claim 1
further comprising:
a switch coupled between the second power supply and the first node and responsive to an enable signal received by the programming circuit, wherein the switch is closed to couple the first node to the second power supply based on the enable signal being in a first state, and wherein the switch is open based on the enable signal being in a second state.
6. The programmable circuit of
claim 5
wherein the switch comprises a transistor.
7. The programmable circuit of
claim 1
wherein the second power supply comprises a ground node.
8. An integrated circuit comprising:
an enabling type programmable circuit providing an enable signal having a programmed state and unprogrammed state; and
at least one second type programmable circuit providing a programmed signal having a first state and a second state and being in a selected one of the first or second states in response to the enable signal being in the unprogrammed state, the at least one programmable circuit including a first anti-fuse and a second anti-fuse, wherein the programmed signal is in the first state in response to the enable signal being in the programmed state and the first anti-fuse being programmed and the programmed signal is in the second state in response to the enable signal being in the programmed state and the second anti-fuse being programmed.
9. The integrated circuit of
claim 8
wherein the integrated circuit is a memory integrated circuit.
10. The integrated circuit of
claim 9
wherein the memory integrated circuit is a dynamic random access memory (DRAM).
11. The integrated circuit of
claim 8
further comprising:
primary circuit elements; and
a redundant circuit element, wherein a selected one of the primary circuit elements is replaceable by the redundant circuit element based on the state of each of the programmed signals from the at least one second type programmable circuit.
12. The integrated circuit of
claim 11
wherein the integrated circuit is a memory integrated circuit comprising an array of memory cells arranged in rows and columns, and wherein the primary circuit elements comprise rows of memory cells.
13. The integrated circuit of
claim 11
wherein the integrated circuit is a memory integrated circuit comprising an array of memory cells arranged in rows and columns, and wherein the primary circuit elements comprise columns of memory cells.
14. The integrated circuit of
claim 11
wherein the integrated circuit is a memory integrated circuit comprising an array of memory cells arranged in rows and columns, and wherein the primary circuit elements comprise rows and columns of memory cells.
15. The integrated circuit of
claim 8
wherein the integrated circuit includes a fuse identification based on the state of each of the programmed signals from the at least one second type programmable circuit.
16. The integrated circuit of
claim 8
wherein the integrated circuit includes a mode of operation based on the state of each of the programmed signals from the at least one second type programmable circuit.
17. A method of programming an integrated circuit comprising the steps of:
providing an enable signal having a programmed state and unprogrammed state;
programming a selected one of a first anti-fuse or a second anti-fuse; and
providing a programmed signal having a first state and a second state, wherein the programmed signal is in a selected one of the first or second states in response to the enable signal being in the unprogrammed state, the programmed signal is in the first state in response to the enable signal being in the programmed state and the first anti-fuse being programmed, and the programmed signal is in the second state in response to the enable signal being in the programmed state and the second anti-fuse being programmed.
18. The method of
claim 17
wherein the integrated circuit is a memory integrated circuit.
19. The method of
claim 17
wherein the integrated circuit includes primary circuit elements and a redundant circuit element, and the method further comprises the step of replacing a selected one of the primary circuit elements with the redundant circuit element based on the state of the programmed signal.
20. The method of
claim 19
wherein the integrated circuit is a memory integrated circuit comprising an array of memory cells arranged in rows and columns, and wherein the primary circuit elements comprise rows of memory cells.
21. The method of
claim 19
wherein the integrated circuit is a memory integrated circuit comprising an array of memory cells arranged in rows and columns, and wherein the primary circuit elements comprise columns of memory cells.
22. The method of
claim 19
wherein the integrated circuit is a memory integrated circuit comprising an array of memory cells arranged in rows and columns, and wherein the primary circuit elements comprise rows and columns of memory cells.
23. The method of
claim 17
further comprising the step of generating a fuse identification based on the state of each of the programmed signals from the at least one second type programmable circuit.
24. The method of
claim 17
further comprising the step of selecting a mode of operation based on the state of each of the programmed signals from the at least one second type programmable circuit.
25. An integrated circuit receiving n address bits and comprising:
primary circuit elements being selectable by binary values of the n address bits;
redundant circuit elements; and
match anti-fuse circuits corresponding to the redundant circuit elements,
each match anti-fuse circuit comprising:
a plurality of programmable circuits, each being coupled to a first power supply and a second power supply and providing a programmed signal corresponding to one of the possible binary values of at least one of the n address bits, wherein each programmable circuit is responsive a binary value of the at least one of the n address bits to activate the programmed signal when the binary value of the at least one of the n address bits corresponds to the programmed signal, each programmable circuit including:
a first node, wherein the state of the programmed signal is based on the state of the first node,
a first anti-fuse having a programmed state and an unprogrammed state and coupling the first node to the first power supply when in the programmed state and decoupling the first node from the first power supply when in the unprogrammed state, and
a second anti-fuse having a programmed state and an unprogrammed state and coupling the first node to the second power supply when in the programmed state and decoupling the first node from the second power supply when in the unprogrammed state; and
a compare circuit coupled to the plurality of programmable circuits for activating a match signal in response to all of the programmed signals being active, wherein the activated match signal is used to disable a primary circuit element from being selected by a corresponding binary value of the n address bits and to enable the redundant circuit element to be selected by the corresponding binary value of the n address bits.
26. The integrated circuit of
claim 25
wherein the integrated circuit is a memory integrated circuit comprising an array of memory cells arranged in rows and columns, and wherein the primary circuit elements comprise rows of memory cells.
27. The integrated circuit of
claim 25
wherein the integrated circuit is a memory integrated circuit comprising an array of memory cells arranged in rows and columns, and wherein the primary circuit elements comprise columns of memory cells.
28. The integrated circuit of
claim 25
wherein the integrated circuit is a memory integrated circuit comprising an array of memory cells arranged in rows and columns, and wherein the primary circuit elements comprise rows and columns of memory cells.
29. The integrated circuit of
claim 25
wherein the integrated circuit is a dynamic random access memory (DRAM).
30. A programmable circuit coupled to a first power supply and a second power supply for providing a programmed signal in an integrated circuit comprising:.
a first node, wherein the state of the programmed signal is based on the state of the first node;
a first anti-fuse including a first terminal coupled to the first node and a second terminal coupled to the first power supply;
a second anti-fuse including a first terminal coupled to the first node and a second terminal coupled to the first power supply;
a first programming bus carrying a sufficient voltage to short the first anti-fuse;
a first switch coupled to the second terminal of the first anti-fuse for coupling the second terminal of the first anti-fuse to the first power supply during normal operation of the integrated circuit and coupling the second terminal of the first anti-fuse to the first programing bus during a first programming operation of the integrated circuit for programming the first anti-fuse to couple the first node to the first power supply;
a second programming bus carrying a sufficient voltage to short the second anti-fuse; and
a second switch coupled to the second terminal of the second anti-fuse for coupling the second terminal of the second anti-fuse to the second power supply during normal operation of the integrated circuit and coupling the second terminal of the second anti-fuse to the second programing bus during a second programming operation of the integrated circuit for programming the second anti-fuse to couple the first node to the second power supply.
31. The programmable circuit of
claim 30
further comprising:
a switch coupled between the second power supply and the first node and responsive to at least one programming control signal received by the programmable circuit, wherein the switch is closed to couple the first node to the second power supply during a programming operation of the integrated circuit and open during normal operations of the integrated circuit.
32. The programmable circuit of
claim 31
wherein the switch comprises a transistor.
33. The programmable circuit of
claim 30
further comprising:
a switch coupled between the second power supply and the first node and responsive to an enable signal received by the programming circuit, wherein the switch is closed to couple the first node to the second power supply based on the enable signal being in a first state, and wherein the switch is open based on the enable signal being in a second state.
34. The programmable circuit of
claim 33
wherein the switch comprises a transistor.
35. The programmable circuit of
claim 30
wherein the second power supply comprises a ground node.
US09/794,685 1996-10-03 2001-02-27 Low current redundancy anti-fuse method and apparatus Expired - Lifetime US6456149B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US09/794,685 US6456149B2 (en) 1996-10-03 2001-02-27 Low current redundancy anti-fuse method and apparatus

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US08/724,851 US6023431A (en) 1996-10-03 1996-10-03 Low current redundancy anti-fuse method and apparatus
US08/896,490 US6462608B2 (en) 1996-10-03 1997-07-18 Low current redundancy anti-fuse apparatus
US09/370,831 US6255894B1 (en) 1996-10-03 1999-08-09 Low current redundancy anti-fuse method and apparatus
US09/794,685 US6456149B2 (en) 1996-10-03 2001-02-27 Low current redundancy anti-fuse method and apparatus

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US09/370,831 Division US6255894B1 (en) 1996-10-03 1999-08-09 Low current redundancy anti-fuse method and apparatus

Publications (2)

Publication Number Publication Date
US20010007431A1 true US20010007431A1 (en) 2001-07-12
US6456149B2 US6456149B2 (en) 2002-09-24

Family

ID=24912182

Family Applications (8)

Application Number Title Priority Date Filing Date
US08/724,851 Expired - Lifetime US6023431A (en) 1996-10-03 1996-10-03 Low current redundancy anti-fuse method and apparatus
US08/896,490 Expired - Lifetime US6462608B2 (en) 1996-10-03 1997-07-18 Low current redundancy anti-fuse apparatus
US08/896,702 Expired - Lifetime US6154398A (en) 1996-10-03 1997-07-18 Low current redundancy anti-fuse method and apparatus
US08/896,701 Expired - Lifetime US5847987A (en) 1996-10-03 1997-07-18 Low currency redundancy anti-fuse method and apparatus
US09/370,831 Expired - Lifetime US6255894B1 (en) 1996-10-03 1999-08-09 Low current redundancy anti-fuse method and apparatus
US09/794,707 Expired - Lifetime US6686790B2 (en) 1996-10-03 2001-02-27 Low current redundancy anti-fuse method and apparatus
US09/794,683 Expired - Fee Related US6351140B2 (en) 1996-10-03 2001-02-27 Low current redundancy anti-fuse method and apparatus
US09/794,685 Expired - Lifetime US6456149B2 (en) 1996-10-03 2001-02-27 Low current redundancy anti-fuse method and apparatus

Family Applications Before (7)

Application Number Title Priority Date Filing Date
US08/724,851 Expired - Lifetime US6023431A (en) 1996-10-03 1996-10-03 Low current redundancy anti-fuse method and apparatus
US08/896,490 Expired - Lifetime US6462608B2 (en) 1996-10-03 1997-07-18 Low current redundancy anti-fuse apparatus
US08/896,702 Expired - Lifetime US6154398A (en) 1996-10-03 1997-07-18 Low current redundancy anti-fuse method and apparatus
US08/896,701 Expired - Lifetime US5847987A (en) 1996-10-03 1997-07-18 Low currency redundancy anti-fuse method and apparatus
US09/370,831 Expired - Lifetime US6255894B1 (en) 1996-10-03 1999-08-09 Low current redundancy anti-fuse method and apparatus
US09/794,707 Expired - Lifetime US6686790B2 (en) 1996-10-03 2001-02-27 Low current redundancy anti-fuse method and apparatus
US09/794,683 Expired - Fee Related US6351140B2 (en) 1996-10-03 2001-02-27 Low current redundancy anti-fuse method and apparatus

Country Status (1)

Country Link
US (8) US6023431A (en)

Families Citing this family (39)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5581111A (en) * 1993-07-07 1996-12-03 Actel Corporation Dielectric-polysilicon-dielectric antifuse for field programmable logic applications
WO1996038861A1 (en) 1995-06-02 1996-12-05 Actel Corporation Raised tungsten plug antifuse and fabrication process
US5986322A (en) * 1995-06-06 1999-11-16 Mccollum; John L. Reduced leakage antifuse structure
US6023431A (en) 1996-10-03 2000-02-08 Micron Technology, Inc. Low current redundancy anti-fuse method and apparatus
US6020777A (en) * 1997-09-26 2000-02-01 International Business Machines Corporation Electrically programmable anti-fuse circuit
US6229378B1 (en) * 1997-12-31 2001-05-08 Intel Corporation Using programmable jumpers to set an IC device's bit-encoded output during manufacturing and testing
EP1118868B1 (en) * 2000-01-18 2005-04-20 Infineon Technologies AG Chip card circuit with monitored test mode access
US6836000B1 (en) * 2000-03-01 2004-12-28 Micron Technology, Inc. Antifuse structure and method of use
US6301164B1 (en) * 2000-08-25 2001-10-09 Micron Technology, Inc. Antifuse method to repair columns in a prefetched output memory architecture
US6570804B1 (en) * 2000-08-29 2003-05-27 Micron Technology, Inc. Fuse read sequence for auto refresh power reduction
US6630724B1 (en) * 2000-08-31 2003-10-07 Micron Technology, Inc. Gate dielectric antifuse circuits and methods for operating same
US6518824B1 (en) * 2000-12-14 2003-02-11 Actel Corporation Antifuse programmable resistor
US6904552B2 (en) 2001-03-15 2005-06-07 Micron Technolgy, Inc. Circuit and method for test and repair
US20020133769A1 (en) * 2001-03-15 2002-09-19 Cowles Timothy B. Circuit and method for test and repair
US6833291B2 (en) 2001-08-16 2004-12-21 Micron Technology, Inc. Semiconductor processing methods
US6972587B2 (en) * 2001-12-19 2005-12-06 Micron Technology, Inc. Built-in self repair for an integrated circuit
US20040176483A1 (en) * 2003-03-05 2004-09-09 Micron Technology, Inc. Cellular materials formed using surface transformation
DE10203129A1 (en) * 2002-01-25 2003-08-07 Infineon Technologies Ag circuitry
US20040018973A1 (en) * 2002-01-25 2004-01-29 University Of Pittsburgh Nuclear matrix protein alterations associated with colon cancer and colon metastasis to the liver, and uses thereof
US6943065B2 (en) * 2002-03-25 2005-09-13 Micron Technology Inc. Scalable high performance antifuse structure and process
US7132348B2 (en) * 2002-03-25 2006-11-07 Micron Technology, Inc. Low k interconnect dielectric using surface transformation
US6657905B1 (en) 2002-05-17 2003-12-02 Micron Technology, Inc. Clamping circuit for the Vpop voltage used to program antifuses
US6851711B2 (en) * 2002-08-16 2005-02-08 Invacare Corporation Vehicle having an anti-dive/lockout mechanism
US6751150B2 (en) * 2002-08-29 2004-06-15 Micron Technology, Inc. Circuits and method to protect a gate dielectric antifuse
US6936909B2 (en) * 2002-08-29 2005-08-30 Micron Technology, Inc. Gate dielectric antifuse circuit to protect a high-voltage transistor
US6759894B2 (en) * 2002-10-31 2004-07-06 Infineon Technologies Ag Method and circuit for controlling fuse blow
US7509543B2 (en) 2003-06-17 2009-03-24 Micron Technology, Inc. Circuit and method for error test, recordation, and repair
US7170315B2 (en) 2003-07-31 2007-01-30 Actel Corporation Programmable system on a chip
US7098721B2 (en) * 2004-09-01 2006-08-29 International Business Machines Corporation Low voltage programmable eFuse with differential sensing scheme
KR100648281B1 (en) * 2005-01-14 2006-11-23 삼성전자주식회사 Nand flash memory device having security redundancy block
US8294505B2 (en) 2005-08-23 2012-10-23 International Business Machines Corporation Stackable programmable passive device and a testing method
JP2007273772A (en) * 2006-03-31 2007-10-18 Fujitsu Ltd Semiconductor device
US8254198B2 (en) * 2007-10-03 2012-08-28 Stmicroelectronics (Crolles 2) Sas Anti-fuse element
JP5458236B2 (en) * 2007-11-02 2014-04-02 ピーエスフォー ルクスコ エスエイアールエル Electric fuse determination circuit and determination method
US8390326B2 (en) * 2009-05-05 2013-03-05 William Marsh Rice University Method for fabrication of a semiconductor element and structure thereof
KR102095856B1 (en) 2013-04-15 2020-04-01 삼성전자주식회사 Semiconductor memory device and body bias method thereof
US9172373B2 (en) * 2013-09-06 2015-10-27 Globalfoundries U.S. 2 Llc Verifying partial good voltage island structures
US9613714B1 (en) * 2016-01-19 2017-04-04 Ememory Technology Inc. One time programming memory cell and memory array for physically unclonable function technology and associated random code generating method
CN116343874A (en) * 2021-12-24 2023-06-27 长鑫存储技术有限公司 Antifuse memory and control method thereof

Family Cites Families (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4686384A (en) * 1985-08-09 1987-08-11 Harris Corporation Fuse programmable DC level generator
IT1232973B (en) * 1987-12-01 1992-03-11 Sgs Microelettronica Spa VOLTAGE POWER SWITCHING DEVICE FOR NON-VOLATILE MEMORIES IN MOS TECHNOLOGY
US5194759A (en) * 1990-05-18 1993-03-16 Actel Corporation Methods for preventing disturbance of antifuses during programming
US5200922A (en) * 1990-10-24 1993-04-06 Rao Kameswara K Redundancy circuit for high speed EPROM and flash memory devices
US5099149A (en) 1990-12-19 1992-03-24 At&T Bell Laboratories Programmable integrated circuit
US5243226A (en) * 1991-07-31 1993-09-07 Quicklogic Corporation Programming of antifuses
US5341267A (en) * 1991-09-23 1994-08-23 Aptix Corporation Structures for electrostatic discharge protection of electrical and other components
US5148391A (en) 1992-02-14 1992-09-15 Micron Technology, Inc. Nonvolatile, zero-power memory cell constructed with capacitor-like antifuses operable at less than power supply voltage
JP2991575B2 (en) * 1992-10-08 1999-12-20 沖電気工業株式会社 Semiconductor integrated circuit
US5264725A (en) * 1992-12-07 1993-11-23 Micron Semiconductor, Inc. Low-current polysilicon fuse
US5508969A (en) * 1993-01-08 1996-04-16 Integrated Device Technology, Inc. Adjacent row shift redundancy circuit having signal restorer coupled to programmable links
US5315177A (en) * 1993-03-12 1994-05-24 Micron Semiconductor, Inc. One time programmable fully-testable programmable logic device with zero power and anti-fuse cell architecture
US5488317A (en) 1993-10-22 1996-01-30 Texas Instruments Incorporated Wired logic functions on FPGA's
US5945840A (en) 1994-02-24 1999-08-31 Micron Technology, Inc. Low current redundancy anti-fuse assembly
US5424672A (en) * 1994-02-24 1995-06-13 Micron Semiconductor, Inc. Low current redundancy fuse assembly
US5424655A (en) * 1994-05-20 1995-06-13 Quicklogic Corporation Programmable application specific integrated circuit employing antifuses and methods therefor
US5566107A (en) * 1995-05-05 1996-10-15 Micron Technology, Inc. Programmable circuit for enabling an associated circuit
US5657293A (en) * 1995-08-23 1997-08-12 Micron Technology, Inc. Integrated circuit memory with back end mode disable
JP2710235B2 (en) * 1995-08-30 1998-02-10 日本電気株式会社 Defect relief judgment circuit
US5841723A (en) * 1996-05-28 1998-11-24 Micron Technology, Inc. Method and apparatus for programming anti-fuses using an isolated well programming circuit
US6023431A (en) * 1996-10-03 2000-02-08 Micron Technology, Inc. Low current redundancy anti-fuse method and apparatus
US5838625A (en) * 1996-10-29 1998-11-17 Micron Technology, Inc. Anti-fuse programming path
US5889414A (en) 1997-04-28 1999-03-30 Mosel Vitelic Corporation Programmable circuits
US5926034A (en) 1997-08-14 1999-07-20 Micron Technology, Inc. Fuse option for multiple logic families on the same die

Also Published As

Publication number Publication date
US5847987A (en) 1998-12-08
US6154398A (en) 2000-11-28
US20010008382A1 (en) 2001-07-19
US6351140B2 (en) 2002-02-26
US6462608B2 (en) 2002-10-08
US6255894B1 (en) 2001-07-03
US20010006351A1 (en) 2001-07-05
US6456149B2 (en) 2002-09-24
US20010013805A1 (en) 2001-08-16
US6023431A (en) 2000-02-08
US6686790B2 (en) 2004-02-03

Similar Documents

Publication Publication Date Title
US6023431A (en) Low current redundancy anti-fuse method and apparatus
US5838625A (en) Anti-fuse programming path
US6088282A (en) System and method for an antifuse bank
US4601019A (en) Memory with redundancy
US6208568B1 (en) Circuit for cancelling and replacing redundant elements
US5485424A (en) Semiconductor memory and redundant-address writing method
US20060203580A1 (en) Programmable element latch circuit
US6144591A (en) Redundancy selection circuit for semiconductor memories
US4485459A (en) Redundant columns for byte wide memories
EP0881571B1 (en) Semiconductor memory device with redundancy
US5912579A (en) Circuit for cancelling and replacing redundant elements
US6208570B1 (en) Redundancy test method for a semiconductor memory
CA2202692C (en) Column redundancy in semiconductor memories
US5058071A (en) Semiconductor memory device having means for repairing the memory device with respect to possible defective memory portions
US5892716A (en) Method and apparatus for global testing the impedance of a programmable element
US5923672A (en) Multipath antifuse circuit
KR100639635B1 (en) Semiconductor memory device with efficient redundancy operation
US6809972B2 (en) Circuit technique for column redundancy fuse latches
US6545920B2 (en) Defective address storage scheme for memory device
US6288964B1 (en) Method to electrically program antifuses
US6275443B1 (en) Latched row or column select enable driver
KR20040017690A (en) Rom memory device having repair function for defective cell and method for reparing the defective cell
JP3437689B2 (en) Semiconductor storage device
CA2246763C (en) Improved redundancy selection circuit for semiconductor memories
JP3734075B2 (en) Compound memory

Legal Events

Date Code Title Description
STCF Information on status: patent grant

Free format text: PATENTED CASE

CC Certificate of correction
FPAY Fee payment

Year of fee payment: 4

FPAY Fee payment

Year of fee payment: 8

FPAY Fee payment

Year of fee payment: 12

AS Assignment

Owner name: U.S. BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT, CALIFORNIA

Free format text: SECURITY INTEREST;ASSIGNOR:MICRON TECHNOLOGY, INC.;REEL/FRAME:038669/0001

Effective date: 20160426

Owner name: U.S. BANK NATIONAL ASSOCIATION, AS COLLATERAL AGEN

Free format text: SECURITY INTEREST;ASSIGNOR:MICRON TECHNOLOGY, INC.;REEL/FRAME:038669/0001

Effective date: 20160426

AS Assignment

Owner name: MORGAN STANLEY SENIOR FUNDING, INC., AS COLLATERAL AGENT, MARYLAND

Free format text: PATENT SECURITY AGREEMENT;ASSIGNOR:MICRON TECHNOLOGY, INC.;REEL/FRAME:038954/0001

Effective date: 20160426

Owner name: MORGAN STANLEY SENIOR FUNDING, INC., AS COLLATERAL

Free format text: PATENT SECURITY AGREEMENT;ASSIGNOR:MICRON TECHNOLOGY, INC.;REEL/FRAME:038954/0001

Effective date: 20160426

AS Assignment

Owner name: U.S. BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT, CALIFORNIA

Free format text: CORRECTIVE ASSIGNMENT TO CORRECT THE REPLACE ERRONEOUSLY FILED PATENT #7358718 WITH THE CORRECT PATENT #7358178 PREVIOUSLY RECORDED ON REEL 038669 FRAME 0001. ASSIGNOR(S) HEREBY CONFIRMS THE SECURITY INTEREST;ASSIGNOR:MICRON TECHNOLOGY, INC.;REEL/FRAME:043079/0001

Effective date: 20160426

Owner name: U.S. BANK NATIONAL ASSOCIATION, AS COLLATERAL AGEN

Free format text: CORRECTIVE ASSIGNMENT TO CORRECT THE REPLACE ERRONEOUSLY FILED PATENT #7358718 WITH THE CORRECT PATENT #7358178 PREVIOUSLY RECORDED ON REEL 038669 FRAME 0001. ASSIGNOR(S) HEREBY CONFIRMS THE SECURITY INTEREST;ASSIGNOR:MICRON TECHNOLOGY, INC.;REEL/FRAME:043079/0001

Effective date: 20160426

AS Assignment

Owner name: MICRON TECHNOLOGY, INC., IDAHO

Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:U.S. BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT;REEL/FRAME:047243/0001

Effective date: 20180629

AS Assignment

Owner name: MICRON TECHNOLOGY, INC., IDAHO

Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:MORGAN STANLEY SENIOR FUNDING, INC., AS COLLATERAL AGENT;REEL/FRAME:050937/0001

Effective date: 20190731