US20110170335A1 - Vertical Non-Volatile Switch with Punchthrough Access and Method of Fabrication Therefor - Google Patents
Vertical Non-Volatile Switch with Punchthrough Access and Method of Fabrication Therefor Download PDFInfo
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- US20110170335A1 US20110170335A1 US13/071,882 US201113071882A US2011170335A1 US 20110170335 A1 US20110170335 A1 US 20110170335A1 US 201113071882 A US201113071882 A US 201113071882A US 2011170335 A1 US2011170335 A1 US 2011170335A1
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Classifications
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- H—ELECTRICITY
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/02—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier
- H01L27/04—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being a semiconductor body
- H01L27/10—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being a semiconductor body including a plurality of individual components in a repetitive configuration
- H01L27/101—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being a semiconductor body including a plurality of individual components in a repetitive configuration including resistors or capacitors only
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- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
- G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
- G11C11/165—Auxiliary circuits
- G11C11/1659—Cell access
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- G—PHYSICS
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- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
- G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
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- G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
- G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
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- G11C13/0002—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00 using resistive RAM [RRAM] elements
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/86—Types of semiconductor device ; Multistep manufacturing processes therefor controllable only by variation of the electric current supplied, or only the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched
- H01L29/861—Diodes
- H01L29/8618—Diodes with bulk potential barrier, e.g. Camel diodes, Planar Doped Barrier diodes, Graded bandgap diodes
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices without a potential-jump barrier or surface barrier, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/20—Multistable switching devices, e.g. memristors
- H10N70/231—Multistable switching devices, e.g. memristors based on solid-state phase change, e.g. between amorphous and crystalline phases, Ovshinsky effect
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- G11C2213/79—Array wherein the access device being a transistor
Definitions
- Data storage devices generally operate to store and retrieve data in a fast and efficient manner.
- Some storage devices utilize a semiconductor array of solid-state memory cells to store individual bits of data.
- Such memory cells can be volatile (e.g., DRAM, SRAM) or non-volatile (RRAM, STRAM, flash, etc.).
- volatile memory cells generally retain data stored in memory only so long as operational power continues to be supplied to the device, while non-volatile memory cells generally retain data storage in memory even in the absence of the application of operational power.
- data storage devices including select devices are manufactured in a lateral configuration along a common substrate.
- spatial problems such as noise and electrical shorts can cause inefficient operation of the device.
- expansion of electrical components vertically can reduce spatial issues commonly encountered.
- Various embodiments of the present invention are directed to a semiconductor device for accessing non-volatile memory cell.
- the semiconductor device has a vertical stack of semiconductor layers including a source, a drain, and a well.
- An application of a drain-source bias voltage to the semiconductor device generates a punchthrough mechanism across the well to initiate a flow of current between the source and the drain.
- a vertical stack of semiconductor layers has a source, a drain, and a well.
- AN application of a drain-source bias voltage generates a punchthrough mechanism across the well to initiate a flow of current between the source and the drain while at least one gate is positioned adjacent a sidewall of the semiconductor device
- a memory device having a cross-point array of memory cells includes a vertical stack of semiconductor layers connected in series with a resistive sense element (RSE).
- the semiconductor device has a source, a drain, and a well to which application of a drain-source bias voltage generates a punchthrough mechanism across the well to initiate a flow of current between the source and the drain that programs the RSE to a selected resistive state.
- FIG. 1 is a generalized functional representation of an exemplary data storage device constructed and operated in accordance with various embodiments of the present invention.
- FIG. 2A shows a memory cell capable of being used in the device of FIG. 1 .
- FIG. 2B displays an exemplary memory cell constructed in accordance with various embodiments of the present inventions.
- FIG. 3A shows an exemplary semiconductor switching device capable of being used in the memory cell of FIGS. 2A-2B .
- FIG. 3B displays an exemplary operation of the memory cell of FIG. 3A in accordance with various embodiments of the present invention.
- FIG. 4 illustrates an exemplary cross-point array of memory cells constructed and operated in accordance with various embodiments of the present invention.
- FIG. 5 graphs the operation of an exemplary semiconductor switching device.
- FIG. 6A-6D generally illustrates an exemplary manufacturing operation performed in accordance with various embodiments of the present invention.
- FIG. 7A shows an exemplary operation of a semiconductor switching device in accordance with various embodiments of the present invention.
- FIG. 7B displays an exemplary construction of a row of memory cells in a cross-point array of memory cells.
- FIG. 8 provides a flowchart of a data access routine performed in accordance with various embodiments of the present invention.
- FIG. 1 provides a functional block representation of a data storage device 100 constructed and operated in accordance with various embodiments of the present invention.
- Top level control of the device 100 is carried out by a suitable controller 102 , which may be a programmable or hardware based microcontroller.
- the controller 102 communicates with a host device via a controller interface (I/F) circuit 104 .
- I/F controller interface
- a memory space is shown at 106 to comprise a number of memory arrays 108 (denoted Array 0-N), although it will be appreciated that a single array can be utilized as desired.
- Each array 108 comprises a block of semiconductor memory of selected storage capacity. Communications between the controller 102 and the memory space 106 are coordinated via the I/F 104 .
- FIG. 2A displays functional block representations of a memory cell 110 constructed and operated in accordance with various embodiments of the present invention.
- the memory cell 110 has a resistive sense element (RSE) 112 connected in series with a switching device 114 .
- the switching device 114 functions to drastically increase the resistance of the memory cell 110 when in an open position, as shown, that effectively prevents current from passing.
- a closed position allows the switching device 114 to receive current and pass it through the memory cell 110 .
- a closed switching device 114 also allows current to pass through the RSE 112 in multiple directions.
- RSE cells over other types of non-volatile memory cells such as EEPROM and flash include the fact that no floating gate is provided in the cell construction. No erase operation is necessary prior to the writing of new data to an existing set of cells. Rather, RSE cells can be individually accessed and written to any desired logical state (e.g., a “0” or “1”) irrespective of the existing state of the RSE cell. Also, write and read power consumption requirements are substantially reduced, significantly faster write and read times can be achieved, and substantially no wear degradation is observed as compared to erasable cells, which have a limited write/erase cycle life.
- a construction of a memory cell 110 with an RSE 112 and a switching device 114 connected in series can have disadvantages, such as large writing current and horizontal surface area requirements.
- the RSE 112 can require large amounts of current to efficiently program data.
- a switching device 114 that can provide such high amount of current to the RSE often corresponds to large horizontal surface area.
- switching devices 114 with high drive currents that have a small horizontal surface area can improve the memory density and operational efficiency of existing memory devices.
- a vertical semiconductor switching device can be used that selectively provides punchthrough conduction of current.
- a semiconductor switching device can be constructed with a vertical stack of semiconductor layers that includes a source, a drain, and a well where the application of a drain-source bias voltage generates a punchthrough mechanism across the well to initiate a flow of current between the source and the drain.
- a small horizontal surface area in combination with large volume current conduction can be implemented to achieve higher memory densities and faster write speeds.
- FIG. 2B displays an exemplary memory cell 120 capable of being used in the memory space 106 of FIG. 1 .
- the memory cell 120 can include an RSE 122 connected in series with a semiconductor switching device 124 .
- the RSE 122 consists of a spin-torque random access memory (STRAM) cell, as shown.
- STRAM spin-torque random access memory
- Such an STRAM cell can have a free magnetic layer 126 and a fixed magnetic reference layer 128 bounding a barrier layer 130 .
- the barrier layer 130 can be characterized as a tunneling barrier constructed of numerous different materials, the various embodiments of the present invention do not limit the possible barrier layer 130 configurations.
- the STRAM cell can have a first electrode 132 and second electrode 134 positioned adjacent to the reference layer 128 and free layer 126 , respectively.
- the first and second electrodes 132 and 134 comprise spin polarizing material that uniformly orients the spin of current passing through the RSE 122 .
- the RSE 122 can be constructed as a resistive random access memory (RRAM) cell with a resistive storage layer disposed between a first electrode layer and a second electrode layer.
- RRAM resistive random access memory
- the RSE 122 would have a naturally high resistive value due to the composition and properties of the storage layer, which can be an oxide (such as titanium dioxide, TiO 2 ) with normally high electrical resistance.
- the storage layer which can be an oxide (such as titanium dioxide, TiO 2 ) with normally high electrical resistance.
- such an RRAM cell could be programmed to a low resistive state with the application of sufficient current to form a filament in the storage layer that connects the first and second electrode layers.
- a programmable metallization memory cell can be utilized as the RSE 122 and constructed with a first electrode and a second electrode that bound a metal layer, embedded layer, and a dielectric layer.
- PMC programmable metallization memory cell
- an adjustment of the relative potential between the first and second electrodes can allow a write current to pass through the RSE 122 through a formed filament.
- a phase change random access memory (PCRAM) cell can be used to store resistive states.
- An exemplary PCRAM cell can have a polycrystalline chalcogenide material media layer disposed between a first electrode and a second electrode.
- the unique behavior of chalcogenide glass of the media layer can allow the application of an amount of heat above the melting point of the chalcogenide material to form an amorphous chalcogenide corresponding to a high resistive state.
- application of heat above the glass transition temperature of the chalcogenide material of the media layer, but below the melting point of the material will crystallize any existing amorphous chalcogenide and program a low resistive state.
- a drain 136 and source 138 can be oriented vertically align and bound a well 140 of dissimilar material.
- an electrode 142 is also coupled adjacent the source layer 138 .
- the semiconductor switching device 124 can restrict current from flowing to the RSE 122 by not having a conductive pathway through the well layer 140 . Conversely, the formation of conductive pathway can allow current to pass through the memory cell 120 in either direction.
- the depiction of the RSE 122 and semiconductor switching device 124 in FIG. 2B is merely exemplary as numerous different configurations can be utilized to construct the memory cell.
- a second barrier layer (not shown) can be coupled between the RSE 122 and semiconductor switching device 124 in part to prevent unwanted flow of current between the components.
- the orientations of the various layers of the RSE 122 and semiconductor switching device 124 can vary, as desired. That is, the physical orientation of the drain layer 136 and source layer 138 can be reversed without deterring from the spirit of the present invention.
- the construction of the memory cell 120 is vertical in nature. That is, the various layers of both the RSE 122 and semiconductor memory device 124 are vertically aligned so that a vertically extending sidewall is formed on at least one side of the components.
- the horizontal surface area of the memory cell 120 can be characterized as the length and width of the electrode layers 132 and 142 in contrast to the depth of the layers displayed in FIG. 2B .
- an exemplary semiconductor switching device 150 is shown as constructed and operated in accordance with various embodiments of the present invention.
- a Pwell layer 152 is disposed and vertically aligned between a source layer 154 and a drain layer 156 .
- the source and drain layers 154 and 156 can be doped in a similar manner (e.g. N+ doped), but such doping is not required or limited.
- the P doped material of the Pwell layer 152 can be used in the source and drain layers 154 and 156 just as the N dope material can be used in the Pwell layer 152 .
- Such an alternative configuration could create a P-N-P vertical stack semiconductor switching device.
- the semiconductor switching device 150 is voltage controlled so that the biasing of voltage between the source layer 154 and drain layer 156 will allow current to pass through the device 150 .
- the various possible configurations of the switching device 150 could have a voltage bias restrict the flow of current through the device 150 .
- FIG. 3B An exemplary operation of the semiconductor switching device 150 of FIG. 3A is generally illustrated in FIG. 3B in accordance with various embodiments of the present invention.
- a voltage potential differential between the source layer 154 and the drain layer 156 can create the merging of a source depleted region 158 and a drain depleted region 160 .
- the region to which the depleted regions merge can be characterized as a punchthrough region 162 .
- biasing the voltage present between the source and drain layers 154 and 156 to a threshold (V p ) forms a highly conductive path from source layer 154 to drain layer 156 , or vice versa, to which current can easily pass.
- the locations and orientation of the various layers of the semiconductor switching device 150 are not limited and can be modified, as desired. For example, modifying the distance between the source layer 154 and the drain layer 156 can enlarge the punchthrough region 162 . Likewise, the source and drain layers 154 and 156 can be reversed in position and/or doped with a different material, as discussed above. Furthermore, a modified punchthrough implant (not shown) can be inserted in the Pwell layer 152 to ensure a predetermined size and orientation of the punchthrough region 162 . Such modifications can be facilitated in various manners to maintain vertical alignment device 150 as well as merging of the depleted regions 158 and 160 in a predetermined region 162 .
- the semiconductor switching device 150 is bidirectional in that a conductive path can be formed through the punchthrough region 162 from either the source or the drain layers 154 or 156 and that conductive region can be maintained regardless of the presence of power to the device 150 .
- the conductive path is not permanent as a change in bias can cause the dissipation of any conductive pathways.
- the semiconductor switching device 150 can operate as a bidirectional non-volatile device in various embodiments.
- FIG. 4 shows an exemplary cross-point array 170 constructed and operated in accordance with various embodiments of the present invention.
- the cross-point array 170 can have a plurality of memory cells 172 , such as the memory cells 150 of FIGS. 3A and 3 B, connected between a bit line 174 and a source line 176 and arranged into rows and columns.
- the cross-point array 170 can be configured, as displayed, to program a resistive state to a selected memory cell 178 by setting a bit line driver 180 to a predetermined high write voltage and setting the corresponding source line driver 182 to a low write voltage.
- multiple memory cells can be programmed either simultaneously or successively along the various rows and columns.
- the path of a write current through the selected memory cell 178 is not fixed and can be adjusted to the opposing direction with manipulation of the bit and source line drivers 180 and 182 .
- a number of non-selected bit lines 184 and source lines 186 are precharged to a bias voltage (e.g. half the write voltage) to prevent leak current from being present during the reading or writing of the selected memory cell 178 . That is, the combination of the semiconductor switching device in each memory cell 172 with the precharging of non-selected bit and source lines 184 and 186 can reduce or eliminate unwanted current from being generated from non-selected memory cells 172 during various read or write operations. For example, the non selected memory cells 172 will not experience a sufficient amount of bias between the precharged non-selected bit and source lines 184 and 186 to conduct current.
- a bias voltage e.g. half the write voltage
- the semiconductor switching device can be constructed and tuned to pass current a memory cell at a predetermined voltage
- the precharging of the non-selected control lines 184 and 186 can eliminate a low voltage potential necessary to generate unwanted leak current. It should be noted that the precharging of non-selected bit and source lines 184 and 186 can be conducted in a biasing scheme, such configuration is not limited to the scheme and can be carried out, as desired.
- the precharge voltage is not fixed or limited as various orientations can be utilized during either the writing or reading of data from a selected memory cell 178 .
- exemplary operational characteristics 190 of a semiconductor switching device are graphed.
- a semiconductor switching device receives a biased voltage, a conductive path through the punchthrough region is not created until a threshold voltage is reached, as displayed by line 192 .
- the threshold voltage is surpassed, the switching device reaches full conductive capacity quickly due to the large conductivity capability of the merged depleted regions in the punchthrough region.
- the switching device can exhibit inverse behavior when voltage of reverse polarity is applied. Hence, the bipolar and bidirectional characteristics of an exemplary semiconductor switching device are evident. Also of note, the current of the switching device rises rapidly at the threshold voltage in either polarity, as shown by segmented line 196 .
- FIGS. 6A-6D An exemplary construction of a vertical semiconductor switching device 200 is displayed in FIGS. 6A-6D in accordance with various embodiments of the present invention.
- a vertical stack of semiconductor layers including at least a source 202 , drain 204 , and Pwell 206 layers, that can be built with implantation and dopant activation on a donor wafer 208 .
- a metallic layer (not shown) can be deposited above the donor wafer 208 to enhance the bonding of the semiconductor layers to the wafer 208 .
- the use of such metallic layer is not required or limited.
- the various semiconductor layers can be doped in a variety of forms including N-P-N and P-N-P, as desired.
- the various dopants can be a number of different materials including, but not limited to, boron, phosphorus, arsenic, indium, and antimony.
- silicon can be used as the donor wafer 208
- various techniques can alternatively be used to grow epitaxial layers of the semiconductors onto silicon (e.g. silicon germanium).
- the switching device is not limited to a single crystalline silicon.
- Such construction can be formed with a vertical epitaxy of silicon germanium, silicon, and silicon germanium to form a heterostructure.
- Various advantages can be experienced with the use of wafer bonding to facilitate vertical layer transfers such as improved manufacturing of complex structures and the ability to transfer a single layer of crystalline semiconductor material in a vertical orientation.
- the semiconductor layers and donor wafer 208 are bonded to contact 210 positioned adjacent an acceptor wafer 212 and insulating material 214 .
- Various bonding and vertical alignment techniques can be used to orient the switching device together, but no one technique is required or limited by the present invention.
- the contact 210 can be constructed of various materials such as pure metals and metal alloys, but such construction is not limited.
- the donor wafer 208 is removed while the contact 210 , acceptor wafer 212 , and insulating material 214 remain. Meanwhile, patterning and alignment of smaller individual switching devices may be carried out with or without alignment marks. Furthermore, various patterning operations can be performed to define the size of the switching devices before or after the bonding and detachment of the donor wafer 208 . Such patterning operations are not limited, or required, and can be conducted, in some embodiments, concurrently with the formation of a resistive sense element.
- a plurality of individual semiconductor stacks 216 are separated by gap 218 while remaining bonded to the contact 210 .
- a chemical etching process can provide precise separation efficiently during manufacture. In some embodiments, such etching can be conducted by transferring a predetermined pattern from a photoresist layer through each semiconductor layer until reaching the contact 210 .
- each individual stack 216 can be protected with insulating material via a variety of techniques.
- One such technique is passivation that forms a silicon dioxide, silicon oxynitride, or silicon nitride.
- the passivation can be done in a variety of manners including, but not limited to, plasma oxidation, plasma nitridation and low temperature dielectric deposition.
- none of the insulating materials or passivation operations are limited, restricted, or preferred.
- FIG. 6D displays several memory cells 220 after being connected in series with an RSE 222 .
- each switching device 200 can have an electrode 224 that may be constructed as a Schottky barrier with respect to the Pwell layer.
- the RSE 220 can be connected to the switching layers from above or below the electrode layer 224 .
- each memory cell 220 can be utilized individually or included in an array of memory cells, such as the cross-point array 170 of FIG. 4 .
- the vertically aligned switching device 200 can be used to provide selective operation of the memory cell 220 .
- the vertical orientation of the memory cell 220 can allow efficient surface area utilization of a data storage device.
- a switching device 200 constructed with wafer bonding, as displayed in FIGS. 6A-6D can provide a selectively large conductive vertical pathway for a memory cell 220 to improve performance and surface area utilization.
- FIG. 7A displays another exemplary semiconductor switching device 230 constructed and operated in accordance with various embodiments of the present invention.
- a source layer 232 and a drain layer 234 are vertically oriented and contactingly engage opposing sides of a Pwell layer 236 .
- a punchthrough region can also be designed within the Pwell layer 230 with a specified configuration of the relationship between the source depleted region 240 and the drain depleted region 242 .
- the punchthrough region 238 can be implemented in the Pwell layer 236 in a variety of different manners including, but not limited to, a modified punchthrough implant.
- One such versatile characteristic can be experienced when a voltage passes through the gate 244 and modulates a current from selected word line 246 and aids in reliably reading the resistive state present in a connected RSE.
- the gate 244 can be constructed as a metal floating gate that can exhibit particular characteristics to yield a bidirectional switching device.
- various operations can be conducted with a voltage connected to the gate 244 that can result in a conductive channel 248 being generated adjacent the sidewall of the Pwell 236 closest to the gate 244 .
- the conductive channel 248 is a MOSFET channel in that it exhibits characteristics similar to a metal oxide semiconductor field effect transistor (MOSFET) with respect to the conduction of current through a switching device.
- the switching device 230 can be configured to function with multiple conductive paths from source layer 232 to drain layer 234 , or vice versa. That is, current can be conducted through both the punchthrough region 238 and the conductive channel 248 simultaneously or in succession based on the selected configuration of the switching device 230 .
- the switching device 230 can also be configured to conduct current through either the punchthrough region 238 or the conductive channel 248 , exclusively.
- the switching device 230 can be selectively configured to generate the conductive channel 248 during particular predetermined situations. Such situations may utilize the conductive channel 248 in a parasitic capacity, such as during various read operations. However, the generation of the conductive channel 248 and the presence of the gate 244 is not required or limited in the use of the switching device 230 .
- one or more gates 244 can be utilized to selectively tune the switching device 230 to correspond to predetermined operational characteristics.
- multiple gates 244 can generate multiple conductive channels 248 on opposing sides of the Pwell layer 238 to selectively adjust a threshold voltage potential bias required to conduct current through the punchthrough region 238 . That is, the minimum voltage bias necessary to conduct current through the punchthrough region 238 can be modified with various gate 244 and conductive channel 248 functions.
- FIG. 7B generally illustrates an exemplary operation of a cross-point array 250 with memory cells constructed with the switching device 230 of FIG. 7A .
- a single gate structure 252 can be used to selectively operate the memory cells 254 connected between a bit line 256 and a source line 258 .
- the gate structure 252 can be positioned adjacent to multiple memory cells 254 along a row, but such orientation is not limited as the gate structure can be positioned along a column of memory cells, individually or in combination with a row gate structure 252 .
- Control of the gate structure 252 can be facilitated by a word line driver 260 in a similar fashion to the bit line driver 262 and source line driver 264 .
- the number and size of the various line drivers 260 , 262 , and 264 are not limited as one, or many, drivers can be utilized in the cross-point array 250 .
- the gate structure 252 can be configured to be isolated to a single memory cell 254 and connected to other gate structures along a row or column by the word line 266 .
- various embodiments of the present invention are constructed so that the gate structure 252 spans multiple rows or columns in the cross-point array 250 .
- the biasing scheme discussed above, can be operated to require a single gate contact while enhancing conduction through the switching device.
- FIG. 8 provides a flowchart of a data access routine 270 performed in accordance with various embodiments of the present invention.
- a vertically aligned memory cell is provided that with an RSE connected in series with a semiconductor switching device.
- the memory cell is positioned in a cross-point array of memory, but such orientation is not limited.
- the switching device is activated at step 274 with the biasing of the source and drain layers with a threshold voltage that allows conduction of a current through the punchthrough region of the Pwell layer of the switching device.
- the threshold voltage, activation, and operation of the switching device can include a gate structure.
- a selected resistive state is programmed to the RSE of the memory cell in step 276 while the switching device is activated. While the data access routine 270 can proceed to end with step 278 , the programmed resistive state can further be read by advancing from step 276 to step 280 or step 282 , depending on the orientation of the memory cell in a cross-point array. If the memory cell is in a cross-point array, a biasing scheme can be conducted in step 280 that precharges non-selected bit and source lines to reduce or eliminated unwanted leak current.
- step 282 the resistive state of the previously programmed memory cell is read with a read current that has a magnitude less than the write current used in step 276 .
- the various configurations of the memory cell in an array is not limited to a cross-point array.
- any number of memory cells can be simultaneously or consecutively read or written with the various steps of the data access routine 270 .
- the various steps of the data access routine 270 are not exclusive and can be modified in timing and operation without deterring from the spirit of the present invention.
- a resistive state can be read without previously programming a resistive state to the RSE.
- the various embodiments illustrated herein provide advantageous access to a memory cell.
- the use of a punchthrough region to conduct large amounts of current through a semiconductor switching device allows for scaleable memory cells that can be reliably programmed with predetermined pulses.
- the versatility of the semiconductor switching device being bidirectional and bipolar, the complexity of a conventional array of memory cells is greatly reduced while improving storage capacity.
- the various embodiments discussed herein have numerous potential applications and are not limited to a certain field of electronic media or type of data storage devices.
Abstract
A semiconductor device for accessing non-volatile memory cell is provided. In some embodiments, the semiconductor device has a vertical stack of semiconductor layers including a source, a drain, and a well. An application of a drain-source bias voltage to the semiconductor device generates a punchthrough mechanism across the well to initiate a flow of current between the source and the drain.
Description
- Data storage devices generally operate to store and retrieve data in a fast and efficient manner. Some storage devices utilize a semiconductor array of solid-state memory cells to store individual bits of data. Such memory cells can be volatile (e.g., DRAM, SRAM) or non-volatile (RRAM, STRAM, flash, etc.).
- As will be appreciated, volatile memory cells generally retain data stored in memory only so long as operational power continues to be supplied to the device, while non-volatile memory cells generally retain data storage in memory even in the absence of the application of operational power.
- In general, data storage devices including select devices are manufactured in a lateral configuration along a common substrate. However, as electronic devices become more complex, spatial problems such as noise and electrical shorts can cause inefficient operation of the device. As such, expansion of electrical components vertically can reduce spatial issues commonly encountered.
- In these and other types of data storage devices, it is often desirable to increase efficiency and performance, particularly by reducing the horizontal surface area of a memory cell or select device.
- Various embodiments of the present invention are directed to a semiconductor device for accessing non-volatile memory cell.
- In some embodiments, the semiconductor device has a vertical stack of semiconductor layers including a source, a drain, and a well. An application of a drain-source bias voltage to the semiconductor device generates a punchthrough mechanism across the well to initiate a flow of current between the source and the drain.
- Further in various embodiments, a vertical stack of semiconductor layers has a source, a drain, and a well. AN application of a drain-source bias voltage generates a punchthrough mechanism across the well to initiate a flow of current between the source and the drain while at least one gate is positioned adjacent a sidewall of the semiconductor device
- In other embodiments, a memory device having a cross-point array of memory cells includes a vertical stack of semiconductor layers connected in series with a resistive sense element (RSE). The semiconductor device has a source, a drain, and a well to which application of a drain-source bias voltage generates a punchthrough mechanism across the well to initiate a flow of current between the source and the drain that programs the RSE to a selected resistive state.
- These and various other features and advantages which characterize the various embodiments of the present invention can be understood in view of the following detailed discussion and the accompanying drawings.
-
FIG. 1 is a generalized functional representation of an exemplary data storage device constructed and operated in accordance with various embodiments of the present invention. -
FIG. 2A shows a memory cell capable of being used in the device ofFIG. 1 . -
FIG. 2B displays an exemplary memory cell constructed in accordance with various embodiments of the present inventions. -
FIG. 3A shows an exemplary semiconductor switching device capable of being used in the memory cell ofFIGS. 2A-2B . -
FIG. 3B displays an exemplary operation of the memory cell ofFIG. 3A in accordance with various embodiments of the present invention. -
FIG. 4 illustrates an exemplary cross-point array of memory cells constructed and operated in accordance with various embodiments of the present invention. -
FIG. 5 graphs the operation of an exemplary semiconductor switching device. -
FIG. 6A-6D generally illustrates an exemplary manufacturing operation performed in accordance with various embodiments of the present invention. -
FIG. 7A shows an exemplary operation of a semiconductor switching device in accordance with various embodiments of the present invention. -
FIG. 7B displays an exemplary construction of a row of memory cells in a cross-point array of memory cells. -
FIG. 8 provides a flowchart of a data access routine performed in accordance with various embodiments of the present invention. -
FIG. 1 provides a functional block representation of adata storage device 100 constructed and operated in accordance with various embodiments of the present invention. Top level control of thedevice 100 is carried out by asuitable controller 102, which may be a programmable or hardware based microcontroller. Thecontroller 102 communicates with a host device via a controller interface (I/F)circuit 104. A memory space is shown at 106 to comprise a number of memory arrays 108 (denoted Array 0-N), although it will be appreciated that a single array can be utilized as desired. Eacharray 108 comprises a block of semiconductor memory of selected storage capacity. Communications between thecontroller 102 and thememory space 106 are coordinated via the I/F 104. -
FIG. 2A displays functional block representations of amemory cell 110 constructed and operated in accordance with various embodiments of the present invention. Thememory cell 110 has a resistive sense element (RSE) 112 connected in series with aswitching device 114. Theswitching device 114 functions to drastically increase the resistance of thememory cell 110 when in an open position, as shown, that effectively prevents current from passing. In contrast, a closed position allows theswitching device 114 to receive current and pass it through thememory cell 110. A closedswitching device 114 also allows current to pass through theRSE 112 in multiple directions. - Advantages of RSE cells over other types of non-volatile memory cells such as EEPROM and flash include the fact that no floating gate is provided in the cell construction. No erase operation is necessary prior to the writing of new data to an existing set of cells. Rather, RSE cells can be individually accessed and written to any desired logical state (e.g., a “0” or “1”) irrespective of the existing state of the RSE cell. Also, write and read power consumption requirements are substantially reduced, significantly faster write and read times can be achieved, and substantially no wear degradation is observed as compared to erasable cells, which have a limited write/erase cycle life.
- However, a construction of a
memory cell 110 with anRSE 112 and aswitching device 114 connected in series can have disadvantages, such as large writing current and horizontal surface area requirements. For example, the RSE 112 can require large amounts of current to efficiently program data. Furthermore, aswitching device 114 that can provide such high amount of current to the RSE often corresponds to large horizontal surface area. Hence, switchingdevices 114 with high drive currents that have a small horizontal surface area can improve the memory density and operational efficiency of existing memory devices. - Accordingly, a vertical semiconductor switching device can be used that selectively provides punchthrough conduction of current. A semiconductor switching device can be constructed with a vertical stack of semiconductor layers that includes a source, a drain, and a well where the application of a drain-source bias voltage generates a punchthrough mechanism across the well to initiate a flow of current between the source and the drain. Thus, a small horizontal surface area in combination with large volume current conduction can be implemented to achieve higher memory densities and faster write speeds.
-
FIG. 2B displays anexemplary memory cell 120 capable of being used in thememory space 106 ofFIG. 1 . Thememory cell 120 can include anRSE 122 connected in series with asemiconductor switching device 124. In some embodiments, theRSE 122 consists of a spin-torque random access memory (STRAM) cell, as shown. Such an STRAM cell can have a freemagnetic layer 126 and a fixedmagnetic reference layer 128 bounding abarrier layer 130. While it can be appreciated that thebarrier layer 130 can be characterized as a tunneling barrier constructed of numerous different materials, the various embodiments of the present invention do not limit thepossible barrier layer 130 configurations. - Further, the STRAM cell can have a
first electrode 132 andsecond electrode 134 positioned adjacent to thereference layer 128 andfree layer 126, respectively. In some embodiments, the first andsecond electrodes RSE 122. - Alternatively, the
RSE 122 can be constructed as a resistive random access memory (RRAM) cell with a resistive storage layer disposed between a first electrode layer and a second electrode layer. As such, theRSE 122 would have a naturally high resistive value due to the composition and properties of the storage layer, which can be an oxide (such as titanium dioxide, TiO2) with normally high electrical resistance. In operation, such an RRAM cell could be programmed to a low resistive state with the application of sufficient current to form a filament in the storage layer that connects the first and second electrode layers. - Additionally, a programmable metallization memory cell (PMC) can be utilized as the
RSE 122 and constructed with a first electrode and a second electrode that bound a metal layer, embedded layer, and a dielectric layer. In some embodiments, an adjustment of the relative potential between the first and second electrodes can allow a write current to pass through theRSE 122 through a formed filament. - In yet another embodiment of the
RSE 122, a phase change random access memory (PCRAM) cell can be used to store resistive states. An exemplary PCRAM cell can have a polycrystalline chalcogenide material media layer disposed between a first electrode and a second electrode. The unique behavior of chalcogenide glass of the media layer can allow the application of an amount of heat above the melting point of the chalcogenide material to form an amorphous chalcogenide corresponding to a high resistive state. In contrast, application of heat above the glass transition temperature of the chalcogenide material of the media layer, but below the melting point of the material will crystallize any existing amorphous chalcogenide and program a low resistive state. - As for the
semiconductor switching device 124, adrain 136 andsource 138 can be oriented vertically align and bound a well 140 of dissimilar material. In various embodiments, anelectrode 142 is also coupled adjacent thesource layer 138. In operation, thesemiconductor switching device 124 can restrict current from flowing to theRSE 122 by not having a conductive pathway through thewell layer 140. Conversely, the formation of conductive pathway can allow current to pass through thememory cell 120 in either direction. - It can be appreciated that the depiction of the
RSE 122 andsemiconductor switching device 124 inFIG. 2B is merely exemplary as numerous different configurations can be utilized to construct the memory cell. For example, a second barrier layer (not shown) can be coupled between theRSE 122 andsemiconductor switching device 124 in part to prevent unwanted flow of current between the components. Furthermore, the orientations of the various layers of theRSE 122 andsemiconductor switching device 124 can vary, as desired. That is, the physical orientation of thedrain layer 136 andsource layer 138 can be reversed without deterring from the spirit of the present invention. - However, it should be noted that in some embodiments the construction of the
memory cell 120 is vertical in nature. That is, the various layers of both theRSE 122 andsemiconductor memory device 124 are vertically aligned so that a vertically extending sidewall is formed on at least one side of the components. Likewise, the horizontal surface area of thememory cell 120 can be characterized as the length and width of the electrode layers 132 and 142 in contrast to the depth of the layers displayed inFIG. 2B . - In
FIGS. 3A-3B , an exemplarysemiconductor switching device 150 is shown as constructed and operated in accordance with various embodiments of the present invention. APwell layer 152 is disposed and vertically aligned between asource layer 154 and adrain layer 156. As shown, the source and drainlayers Pwell layer 152 can be used in the source and drainlayers Pwell layer 152. Such an alternative configuration could create a P-N-P vertical stack semiconductor switching device. - In operation, the
semiconductor switching device 150 is voltage controlled so that the biasing of voltage between thesource layer 154 anddrain layer 156 will allow current to pass through thedevice 150. However, it should be noted that the various possible configurations of theswitching device 150 could have a voltage bias restrict the flow of current through thedevice 150. - An exemplary operation of the
semiconductor switching device 150 ofFIG. 3A is generally illustrated inFIG. 3B in accordance with various embodiments of the present invention. A voltage potential differential between thesource layer 154 and thedrain layer 156 can create the merging of a source depletedregion 158 and a drain depletedregion 160. The region to which the depleted regions merge can be characterized as apunchthrough region 162. In some embodiments, biasing the voltage present between the source and drainlayers source layer 154 to drainlayer 156, or vice versa, to which current can easily pass. - It should be noted that the locations and orientation of the various layers of the
semiconductor switching device 150 are not limited and can be modified, as desired. For example, modifying the distance between thesource layer 154 and thedrain layer 156 can enlarge thepunchthrough region 162. Likewise, the source and drainlayers Pwell layer 152 to ensure a predetermined size and orientation of thepunchthrough region 162. Such modifications can be facilitated in various manners to maintainvertical alignment device 150 as well as merging of the depletedregions predetermined region 162. - Further in various embodiments, the
semiconductor switching device 150 is bidirectional in that a conductive path can be formed through thepunchthrough region 162 from either the source or the drain layers 154 or 156 and that conductive region can be maintained regardless of the presence of power to thedevice 150. However, the conductive path is not permanent as a change in bias can cause the dissipation of any conductive pathways. Thus, thesemiconductor switching device 150 can operate as a bidirectional non-volatile device in various embodiments. -
FIG. 4 shows an exemplarycross-point array 170 constructed and operated in accordance with various embodiments of the present invention. Thecross-point array 170 can have a plurality ofmemory cells 172, such as thememory cells 150 ofFIGS. 3A and 3B, connected between abit line 174 and asource line 176 and arranged into rows and columns. Thecross-point array 170 can be configured, as displayed, to program a resistive state to a selectedmemory cell 178 by setting abit line driver 180 to a predetermined high write voltage and setting the correspondingsource line driver 182 to a low write voltage. - However, it can be appreciated that multiple memory cells can be programmed either simultaneously or successively along the various rows and columns. Similarly, it should be noted that the path of a write current through the selected
memory cell 178 is not fixed and can be adjusted to the opposing direction with manipulation of the bit andsource line drivers - In an exemplary biasing scheme, a number of
non-selected bit lines 184 andsource lines 186 are precharged to a bias voltage (e.g. half the write voltage) to prevent leak current from being present during the reading or writing of the selectedmemory cell 178. That is, the combination of the semiconductor switching device in eachmemory cell 172 with the precharging of non-selected bit andsource lines non-selected memory cells 172 during various read or write operations. For example, the non selectedmemory cells 172 will not experience a sufficient amount of bias between the precharged non-selected bit andsource lines - While the semiconductor switching device can be constructed and tuned to pass current a memory cell at a predetermined voltage, the precharging of the
non-selected control lines source lines memory cell 178. - In
FIG. 5 , exemplaryoperational characteristics 190 of a semiconductor switching device are graphed. As a semiconductor switching device receives a biased voltage, a conductive path through the punchthrough region is not created until a threshold voltage is reached, as displayed byline 192. However, as the threshold voltage is surpassed, the switching device reaches full conductive capacity quickly due to the large conductivity capability of the merged depleted regions in the punchthrough region. - Further, the switching device can exhibit inverse behavior when voltage of reverse polarity is applied. Hence, the bipolar and bidirectional characteristics of an exemplary semiconductor switching device are evident. Also of note, the current of the switching device rises rapidly at the threshold voltage in either polarity, as shown by
segmented line 196. - An exemplary construction of a vertical
semiconductor switching device 200 is displayed inFIGS. 6A-6D in accordance with various embodiments of the present invention. A vertical stack of semiconductor layers, including at least asource 202, drain 204, andPwell 206 layers, that can be built with implantation and dopant activation on adonor wafer 208. In some embodiments, a metallic layer (not shown) can be deposited above thedonor wafer 208 to enhance the bonding of the semiconductor layers to thewafer 208. However, the use of such metallic layer is not required or limited. - It should be noted that the various semiconductor layers can be doped in a variety of forms including N-P-N and P-N-P, as desired. Similarly, the various dopants can be a number of different materials including, but not limited to, boron, phosphorus, arsenic, indium, and antimony. While silicon can be used as the
donor wafer 208, various techniques can alternatively be used to grow epitaxial layers of the semiconductors onto silicon (e.g. silicon germanium). - Likewise, the switching device is not limited to a single crystalline silicon. Such construction can be formed with a vertical epitaxy of silicon germanium, silicon, and silicon germanium to form a heterostructure. Various advantages can be experienced with the use of wafer bonding to facilitate vertical layer transfers such as improved manufacturing of complex structures and the ability to transfer a single layer of crystalline semiconductor material in a vertical orientation.
- Further in various embodiments shown in
FIG. 6A , the semiconductor layers anddonor wafer 208 are bonded to contact 210 positioned adjacent anacceptor wafer 212 and insulatingmaterial 214. Various bonding and vertical alignment techniques can be used to orient the switching device together, but no one technique is required or limited by the present invention. Likewise, thecontact 210 can be constructed of various materials such as pure metals and metal alloys, but such construction is not limited. - In
FIG. 6B , thedonor wafer 208 is removed while thecontact 210,acceptor wafer 212, and insulatingmaterial 214 remain. Meanwhile, patterning and alignment of smaller individual switching devices may be carried out with or without alignment marks. Furthermore, various patterning operations can be performed to define the size of the switching devices before or after the bonding and detachment of thedonor wafer 208. Such patterning operations are not limited, or required, and can be conducted, in some embodiments, concurrently with the formation of a resistive sense element. - In regard to
FIG. 6C , a plurality ofindividual semiconductor stacks 216 are separated bygap 218 while remaining bonded to thecontact 210. While various separation techniques can be utilized without restriction or limitation, a chemical etching process can provide precise separation efficiently during manufacture. In some embodiments, such etching can be conducted by transferring a predetermined pattern from a photoresist layer through each semiconductor layer until reaching thecontact 210. - In addition, at least one vertical sidewall of each
individual stack 216 can be protected with insulating material via a variety of techniques. One such technique is passivation that forms a silicon dioxide, silicon oxynitride, or silicon nitride. Furthermore, the passivation can be done in a variety of manners including, but not limited to, plasma oxidation, plasma nitridation and low temperature dielectric deposition. However, none of the insulating materials or passivation operations are limited, restricted, or preferred. - During various operations of a
semiconductor switching device 200, a gate may be used. As such, a gate structure can be connected to theindividual stack 216 during construction. Otherwise, a dielectric can be inserted in thegap 218 to fully isolate thestacks 216. Finally,FIG. 6D displaysseveral memory cells 220 after being connected in series with anRSE 222. As discussed above, each switchingdevice 200 can have anelectrode 224 that may be constructed as a Schottky barrier with respect to the Pwell layer. It should be noted that theRSE 220 can be connected to the switching layers from above or below theelectrode layer 224. As a result, eachmemory cell 220 can be utilized individually or included in an array of memory cells, such as thecross-point array 170 ofFIG. 4 . - In operation, the vertically aligned
switching device 200 can be used to provide selective operation of thememory cell 220. The vertical orientation of thememory cell 220 can allow efficient surface area utilization of a data storage device. Accordingly, aswitching device 200 constructed with wafer bonding, as displayed inFIGS. 6A-6D , can provide a selectively large conductive vertical pathway for amemory cell 220 to improve performance and surface area utilization. -
FIG. 7A displays another exemplarysemiconductor switching device 230 constructed and operated in accordance with various embodiments of the present invention. Asource layer 232 and adrain layer 234 are vertically oriented and contactingly engage opposing sides of aPwell layer 236. A punchthrough region can also be designed within thePwell layer 230 with a specified configuration of the relationship between the source depletedregion 240 and the drain depletedregion 242. However, it should be noted that thepunchthrough region 238 can be implemented in thePwell layer 236 in a variety of different manners including, but not limited to, a modified punchthrough implant. - While various memory cell operations can be performed by the
switching device 230, increased versatility can be achieved with the addition of agate 244 positioned adjacent a sidewall of theswitching device 230. One such versatile characteristic can be experienced when a voltage passes through thegate 244 and modulates a current from selectedword line 246 and aids in reliably reading the resistive state present in a connected RSE. As can be appreciated, thegate 244 can be constructed as a metal floating gate that can exhibit particular characteristics to yield a bidirectional switching device. - Further, various operations can be conducted with a voltage connected to the
gate 244 that can result in aconductive channel 248 being generated adjacent the sidewall of thePwell 236 closest to thegate 244. In some embodiments, theconductive channel 248 is a MOSFET channel in that it exhibits characteristics similar to a metal oxide semiconductor field effect transistor (MOSFET) with respect to the conduction of current through a switching device. However, theswitching device 230 can be configured to function with multiple conductive paths fromsource layer 232 to drainlayer 234, or vice versa. That is, current can be conducted through both thepunchthrough region 238 and theconductive channel 248 simultaneously or in succession based on the selected configuration of theswitching device 230. Furthermore, theswitching device 230 can also be configured to conduct current through either thepunchthrough region 238 or theconductive channel 248, exclusively. - In sum, the
switching device 230 can be selectively configured to generate theconductive channel 248 during particular predetermined situations. Such situations may utilize theconductive channel 248 in a parasitic capacity, such as during various read operations. However, the generation of theconductive channel 248 and the presence of thegate 244 is not required or limited in the use of theswitching device 230. - Alternatively, one or
more gates 244 can be utilized to selectively tune theswitching device 230 to correspond to predetermined operational characteristics. For example,multiple gates 244 can generate multipleconductive channels 248 on opposing sides of thePwell layer 238 to selectively adjust a threshold voltage potential bias required to conduct current through thepunchthrough region 238. That is, the minimum voltage bias necessary to conduct current through thepunchthrough region 238 can be modified withvarious gate 244 andconductive channel 248 functions. -
FIG. 7B generally illustrates an exemplary operation of across-point array 250 with memory cells constructed with theswitching device 230 ofFIG. 7A . Asingle gate structure 252 can be used to selectively operate thememory cells 254 connected between abit line 256 and asource line 258. As displayed, thegate structure 252 can be positioned adjacent tomultiple memory cells 254 along a row, but such orientation is not limited as the gate structure can be positioned along a column of memory cells, individually or in combination with arow gate structure 252. Control of thegate structure 252 can be facilitated by aword line driver 260 in a similar fashion to thebit line driver 262 andsource line driver 264. However, the number and size of thevarious line drivers cross-point array 250. - It should be noted that the
gate structure 252 can be configured to be isolated to asingle memory cell 254 and connected to other gate structures along a row or column by theword line 266. In contrast, various embodiments of the present invention are constructed so that thegate structure 252 spans multiple rows or columns in thecross-point array 250. Furthermore, the biasing scheme, discussed above, can be operated to require a single gate contact while enhancing conduction through the switching device. -
FIG. 8 provides a flowchart of adata access routine 270 performed in accordance with various embodiments of the present invention. Initially atstep 272, a vertically aligned memory cell is provided that with an RSE connected in series with a semiconductor switching device. In some embodiments, the memory cell is positioned in a cross-point array of memory, but such orientation is not limited. The switching device is activated atstep 274 with the biasing of the source and drain layers with a threshold voltage that allows conduction of a current through the punchthrough region of the Pwell layer of the switching device. As discussed above, the threshold voltage, activation, and operation of the switching device can include a gate structure. - In addition, a selected resistive state is programmed to the RSE of the memory cell in
step 276 while the switching device is activated. While thedata access routine 270 can proceed to end withstep 278, the programmed resistive state can further be read by advancing fromstep 276 to step 280 or step 282, depending on the orientation of the memory cell in a cross-point array. If the memory cell is in a cross-point array, a biasing scheme can be conducted instep 280 that precharges non-selected bit and source lines to reduce or eliminated unwanted leak current. - In
step 282, the resistive state of the previously programmed memory cell is read with a read current that has a magnitude less than the write current used instep 276. It can be appreciated that the various configurations of the memory cell in an array is not limited to a cross-point array. Likewise, any number of memory cells can be simultaneously or consecutively read or written with the various steps of thedata access routine 270. Furthermore, the various steps of thedata access routine 270 are not exclusive and can be modified in timing and operation without deterring from the spirit of the present invention. - For example, a resistive state can be read without previously programming a resistive state to the RSE.
- As can be appreciated by one skilled in the art, the various embodiments illustrated herein provide advantageous access to a memory cell. The use of a punchthrough region to conduct large amounts of current through a semiconductor switching device allows for scaleable memory cells that can be reliably programmed with predetermined pulses. With the versatility of the semiconductor switching device being bidirectional and bipolar, the complexity of a conventional array of memory cells is greatly reduced while improving storage capacity. However, it will be appreciated that the various embodiments discussed herein have numerous potential applications and are not limited to a certain field of electronic media or type of data storage devices.
- It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the invention, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangements of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
Claims (20)
1. A memory cell comprising a vertical stack of semiconductor layers and comprising a source, a drain, and a well without an associated gate structure, wherein application of a drain-source bias voltage generates a punchthrough mechanism across the well to initiate a flow of current between the source and the drain.
2. The memory cell of claim 1 , in combination with a resistive sense element (RSE), wherein said flow of current programs the RSE to a selected resistive state.
3. The memory cell of claim 1 , wherein the vertical stack of semiconductor layers is bidirectional.
4. The memory cell of claim 1 , wherein the vertical stack of semiconductor layers is a silicon compound.
5. The memory cell of claim 1 , wherein the source, drain, and well are doped to form an N-P-N mode.
6. The memory cell of claim 1 , wherein the source, drain, and well are doped to form an P-N-P mode.
7. The memory cell of claim 1 , wherein punchthrough mechanism extends adjacent a MOSFET channel in said well.
8. The memory cell of claim 1 , wherein the vertical stack of semiconductor layers has an insulating material on at least one sidewall.
9. The memory cell of claim 2 , wherein the RSE is connected vertically adjacent to the vertical stack of semiconductor layers.
10. The memory cell of claim 1 , wherein the punchthrough mechanism is generated with bidirectional voltage.
11. The memory cell of claim 1 , wherein the vertical stack of semiconductor layers is a bipolar and bidirectional switch in a cross-point array of memory.
12. A method comprising:
providing a memory cell comprising a resistive sense element (RSE) and a vertically stacked switching device comprising a source region, a drain region and a well region therebetween without an associated gate structure; and
using a punchthrough mechanism of the switching device to conduct current from the drain to the source.
13. The method of claim 12 , wherein a plurality of memory cells are each connected between one of a plurality of bit lines and one of a plurality of source lines in a cross-point array of memory.
14. The method of claim 13 , wherein a selected memory cell is connected between a first bit line and a first source line.
15. The method of claim 14 , wherein the first bit line is set to a high voltage and the first source line is set to a low voltage while the remaining plurality of bit lines and source lines are each set to a half voltage to prevent leak current from reaching the selected memory cell.
16. The method of claim 12 , wherein the source and drain of the vertically stacked switching device of the memory cell are biased with a threshold voltage to conduct current through the punchthrough mechanism.
17. The method of claim 16 , wherein a read current is subsequently passed through the RSE to read a programmed resistive state of the RSE.
18. The method of claim 16 , wherein a write current is subsequently passed through the RSE to program a resistive state of the RSE.
19. A data storage device comprising a plurality of memory cells each connected between and controlled by one of a plurality of first and second control lines, each memory cell comprising a resistive sense element (RSE) connected in series with a vertical stack of semiconductor layers and comprising a source, a drain, and a well without an associated gate structure, wherein application of a drain-source bias voltage generates a punchthrough mechanism across the well to initiate a flow of current between the source and the drain to the RSE.
20. The data storage device of claim 19 , wherein a selected memory cell coupled between a selected first and second control line, the first selected control line charged to a first read voltage, the second selected control line charged to a second read voltage, and the memory cell is read after each non-selected first and second control line is precharged to a desired voltage that is between the first and second read voltages.
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US13/071,882 US20110170335A1 (en) | 2009-07-13 | 2011-03-25 | Vertical Non-Volatile Switch with Punchthrough Access and Method of Fabrication Therefor |
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US12/502,089 US8208285B2 (en) | 2009-07-13 | 2009-07-13 | Vertical non-volatile switch with punchthrough access and method of fabrication therefor |
US13/071,882 US20110170335A1 (en) | 2009-07-13 | 2011-03-25 | Vertical Non-Volatile Switch with Punchthrough Access and Method of Fabrication Therefor |
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US12/502,089 Division US8208285B2 (en) | 2009-07-13 | 2009-07-13 | Vertical non-volatile switch with punchthrough access and method of fabrication therefor |
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US20110170335A1 true US20110170335A1 (en) | 2011-07-14 |
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US12/502,089 Active 2029-08-10 US8208285B2 (en) | 2009-07-13 | 2009-07-13 | Vertical non-volatile switch with punchthrough access and method of fabrication therefor |
US13/071,882 Abandoned US20110170335A1 (en) | 2009-07-13 | 2011-03-25 | Vertical Non-Volatile Switch with Punchthrough Access and Method of Fabrication Therefor |
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US (2) | US8208285B2 (en) |
JP (1) | JP5555770B2 (en) |
KR (1) | KR101433184B1 (en) |
CN (1) | CN102844865B (en) |
WO (1) | WO2011008622A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8949567B2 (en) | 2013-02-26 | 2015-02-03 | Seagate Technology Llc | Cross-point resistive-based memory architecture |
US9263129B2 (en) * | 2014-05-15 | 2016-02-16 | Commissariat à l'énergie atomique et aux énergies alternatives | Method for determining programming parameters for programming a resistive random access memory |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8462580B2 (en) * | 2010-11-17 | 2013-06-11 | Sandisk 3D Llc | Memory system with reversible resistivity-switching using pulses of alternatrie polarity |
WO2014148872A1 (en) | 2013-03-21 | 2014-09-25 | 한양대학교 산학협력단 | Two-terminal switching element having bidirectional switching characteristic, resistive memory cross-point array including same, and method for manufacturing two-terminal switching element and cross-point resistive memory array |
US8953387B2 (en) | 2013-06-10 | 2015-02-10 | Micron Technology, Inc. | Apparatuses and methods for efficient write in a cross-point array |
EP2824096A1 (en) * | 2013-07-09 | 2015-01-14 | Solvay SA | Fluorinated carbonates comprising double bond-containing groups, methods for their manufacture and uses thereof |
US9312005B2 (en) | 2013-09-10 | 2016-04-12 | Micron Technology, Inc. | Accessing memory cells in parallel in a cross-point array |
US9324423B2 (en) | 2014-05-07 | 2016-04-26 | Micron Technology, Inc. | Apparatuses and methods for bi-directional access of cross-point arrays |
US9472281B1 (en) * | 2015-06-30 | 2016-10-18 | HGST Netherlands B.V. | Non-volatile memory with adjustable cell bit shape |
US10497692B2 (en) * | 2017-08-29 | 2019-12-03 | Globalfoundries Inc. | SRAM structure with alternate gate pitches |
Citations (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4247915A (en) * | 1979-01-02 | 1981-01-27 | Texas Instruments Incorporated | Punch-through load devices in high density static memory cell |
US4901132A (en) * | 1986-06-09 | 1990-02-13 | Texas Instruments Incorporated | Semiconductor integrated circuit with switching bipolar transistors having high withstand voltage capability |
US5365083A (en) * | 1990-11-29 | 1994-11-15 | Kawasaki Steel Corporation | Semiconductor device of band-to-band tunneling type |
US5903492A (en) * | 1996-06-10 | 1999-05-11 | Kabushiki Kaisha Toshiba | Semiconductor memory device and various systems mounting them |
US5926412A (en) * | 1992-02-09 | 1999-07-20 | Raytheon Company | Ferroelectric memory structure |
US20020081822A1 (en) * | 1999-02-02 | 2002-06-27 | Kazutaka Yanagita | Composite member and separating method therefor, bonded substrate stack and separating method therefor, transfer method for transfer layer, and SOI substrate manufacturing method |
US20040084725A1 (en) * | 2002-11-01 | 2004-05-06 | Toyota Jidosha Kabushiki Kaisha | Field-effect-type semiconductor device |
US20050280061A1 (en) * | 2004-06-21 | 2005-12-22 | Sang-Yun Lee | Vertical memory device structures |
US20050280155A1 (en) * | 2004-06-21 | 2005-12-22 | Sang-Yun Lee | Semiconductor bonding and layer transfer method |
US7052941B2 (en) * | 2003-06-24 | 2006-05-30 | Sang-Yun Lee | Method for making a three-dimensional integrated circuit structure |
US7051941B2 (en) * | 2003-03-03 | 2006-05-30 | Nisca Corporation | Image reading unit and image reading apparatus |
US20080048327A1 (en) * | 2004-06-21 | 2008-02-28 | Sang-Yun Lee | Electronic circuit with embedded memory |
US20080108212A1 (en) * | 2006-10-19 | 2008-05-08 | Atmel Corporation | High voltage vertically oriented eeprom device |
US7440317B2 (en) * | 2002-08-30 | 2008-10-21 | Micron Technology, Inc. | One transistor SOI non-volatile random access memory cell |
US20090072279A1 (en) * | 2007-08-29 | 2009-03-19 | Ecole Polytechnique Federale De Lausanne (Epfl) | Capacitor-less memory and abrupt switch based on hysteresis characteristics in punch-through impact ionization mos transistor (PI-MOS) |
US20090296449A1 (en) * | 2008-06-02 | 2009-12-03 | Stefan Slesazeck | Integrated Circuit and Method of Operating an Integrated Circuit |
US20100110756A1 (en) * | 2008-10-30 | 2010-05-06 | Seagate Technology Llc | Variable resistive memory punchthrough access method |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5370768A (en) * | 1976-12-07 | 1978-06-23 | Fujitsu Ltd | Integrated circuit |
US5592005A (en) * | 1995-03-31 | 1997-01-07 | Siliconix Incorporated | Punch-through field effect transistor |
DE60030059T2 (en) * | 1999-04-08 | 2007-03-29 | Koninklijke Philips Electronics N.V. | BREAKTHROUGH DIODE AND METHOD OF MANUFACTURE |
EP2988331B1 (en) | 2000-08-14 | 2019-01-09 | SanDisk Technologies LLC | Semiconductor memory device |
KR20030060327A (en) | 2002-01-08 | 2003-07-16 | 삼성전자주식회사 | High density magnetic memory device and operating method thereof |
US7606059B2 (en) * | 2003-03-18 | 2009-10-20 | Kabushiki Kaisha Toshiba | Three-dimensional programmable resistance memory device with a read/write circuit stacked under a memory cell array |
KR20070049139A (en) * | 2004-06-16 | 2007-05-10 | 코닌클리즈케 필립스 일렉트로닉스 엔.브이. | Electrical device and method of manufacturing therefor |
US20080315260A1 (en) | 2005-03-22 | 2008-12-25 | Russell Duane | Diode Structure |
WO2007128738A1 (en) | 2006-05-02 | 2007-11-15 | Innovative Silicon Sa | Semiconductor memory cell and array using punch-through to program and read same |
DE102008026432A1 (en) | 2008-06-02 | 2009-12-10 | Qimonda Ag | Integrated circuit for use in e.g. magnetoresistive RAM module, has set of resistance change memory elements, and set of memory element selection devices that are floating-body-selection devices such as FETs or thyristors |
-
2009
- 2009-07-13 US US12/502,089 patent/US8208285B2/en active Active
-
2010
- 2010-07-08 CN CN201080032403.4A patent/CN102844865B/en not_active Expired - Fee Related
- 2010-07-08 KR KR1020127003824A patent/KR101433184B1/en active IP Right Grant
- 2010-07-08 JP JP2012520676A patent/JP5555770B2/en not_active Expired - Fee Related
- 2010-07-08 WO PCT/US2010/041318 patent/WO2011008622A1/en active Application Filing
-
2011
- 2011-03-25 US US13/071,882 patent/US20110170335A1/en not_active Abandoned
Patent Citations (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4247915A (en) * | 1979-01-02 | 1981-01-27 | Texas Instruments Incorporated | Punch-through load devices in high density static memory cell |
US4901132A (en) * | 1986-06-09 | 1990-02-13 | Texas Instruments Incorporated | Semiconductor integrated circuit with switching bipolar transistors having high withstand voltage capability |
US5365083A (en) * | 1990-11-29 | 1994-11-15 | Kawasaki Steel Corporation | Semiconductor device of band-to-band tunneling type |
US5926412A (en) * | 1992-02-09 | 1999-07-20 | Raytheon Company | Ferroelectric memory structure |
US5903492A (en) * | 1996-06-10 | 1999-05-11 | Kabushiki Kaisha Toshiba | Semiconductor memory device and various systems mounting them |
US20020081822A1 (en) * | 1999-02-02 | 2002-06-27 | Kazutaka Yanagita | Composite member and separating method therefor, bonded substrate stack and separating method therefor, transfer method for transfer layer, and SOI substrate manufacturing method |
US7440317B2 (en) * | 2002-08-30 | 2008-10-21 | Micron Technology, Inc. | One transistor SOI non-volatile random access memory cell |
US20040084725A1 (en) * | 2002-11-01 | 2004-05-06 | Toyota Jidosha Kabushiki Kaisha | Field-effect-type semiconductor device |
US7051941B2 (en) * | 2003-03-03 | 2006-05-30 | Nisca Corporation | Image reading unit and image reading apparatus |
US7052941B2 (en) * | 2003-06-24 | 2006-05-30 | Sang-Yun Lee | Method for making a three-dimensional integrated circuit structure |
US20050280155A1 (en) * | 2004-06-21 | 2005-12-22 | Sang-Yun Lee | Semiconductor bonding and layer transfer method |
US20080048327A1 (en) * | 2004-06-21 | 2008-02-28 | Sang-Yun Lee | Electronic circuit with embedded memory |
US20050280061A1 (en) * | 2004-06-21 | 2005-12-22 | Sang-Yun Lee | Vertical memory device structures |
US20080108212A1 (en) * | 2006-10-19 | 2008-05-08 | Atmel Corporation | High voltage vertically oriented eeprom device |
US20090072279A1 (en) * | 2007-08-29 | 2009-03-19 | Ecole Polytechnique Federale De Lausanne (Epfl) | Capacitor-less memory and abrupt switch based on hysteresis characteristics in punch-through impact ionization mos transistor (PI-MOS) |
US20090296449A1 (en) * | 2008-06-02 | 2009-12-03 | Stefan Slesazeck | Integrated Circuit and Method of Operating an Integrated Circuit |
US7738279B2 (en) * | 2008-06-02 | 2010-06-15 | Qimonda Ag | Integrated circuit and method of operating an integrated circuit |
US20100110756A1 (en) * | 2008-10-30 | 2010-05-06 | Seagate Technology Llc | Variable resistive memory punchthrough access method |
US20110026307A1 (en) * | 2008-10-30 | 2011-02-03 | Seagate Technology Llc | Variable resistive memory punchthrough access method |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8949567B2 (en) | 2013-02-26 | 2015-02-03 | Seagate Technology Llc | Cross-point resistive-based memory architecture |
US9263129B2 (en) * | 2014-05-15 | 2016-02-16 | Commissariat à l'énergie atomique et aux énergies alternatives | Method for determining programming parameters for programming a resistive random access memory |
Also Published As
Publication number | Publication date |
---|---|
US8208285B2 (en) | 2012-06-26 |
US20110007547A1 (en) | 2011-01-13 |
JP2012533191A (en) | 2012-12-20 |
JP5555770B2 (en) | 2014-07-23 |
WO2011008622A1 (en) | 2011-01-20 |
KR101433184B1 (en) | 2014-08-22 |
CN102844865B (en) | 2016-04-06 |
CN102844865A (en) | 2012-12-26 |
KR20120098590A (en) | 2012-09-05 |
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