CN103151079B

CN103151079B - Detect the method for RAM production defect

Info

Publication number: CN103151079B
Application number: CN201210582762.8A
Authority: CN
Inventors: 赵阳; 张洪柳; 孙晓宁; 刘大铕; 王运哲; 刘守浩
Original assignee: Shandong Sinochip Semiconductors Co Ltd
Current assignee: Shandong Sinochip Semiconductors Co Ltd
Priority date: 2012-12-28
Filing date: 2012-12-28
Publication date: 2016-01-06
Anticipated expiration: 2032-12-28
Also published as: CN103151079A

Abstract

The invention discloses a kind of method detecting RAM production defect, according to the present invention, realize the test for a rear step based on last testing procedure RAM current address state, need not test at every turn only test a test point, thus need not reset for each RAM and reuse method of testing, efficiency improves greatly.

Description

Detect the method for RAM production defect

Technical field

The present invention relates to a kind of method detecting RAM production defect.

Background technology

Macroscopic view RAM(RandomAccessMemory, random access memory) test comprise storage unit test, data line test and address wire test.For control line, owing to incidentally completing in the test to the above two, therefore do not do special test.And the test of address wire is always carried out in the normal situation of tentation data line, obviously need the test of advanced row data line, then just can carry out the test of address wire.

Along with the increase of footprint and the raising of integrated level, in system, the quantity of RAM gets more and more, and width and the degree of depth are also different, also need to carry out refinement to its test.Will complete the test to RAM in system, the method for testing adopted all can not once survey entirely all defects, not only increases the time of test, and adds testing complex degree and testing cost in the past.

In the production run of integrated circuit, due to technology or other reasons, easily cause the defect of RAM in circuit.

The basic generation defect of current RAM is as follows:

◆ Stuck-AtFault (SAF, stuck-at fault): a certain position in RAM is fixed as 1 or 0, cannot write contrary value; Certain line in other words in RAM circuit should according to the value of its source node value, but owing to there is certain fault, its logical value is fixed as 0 or 1; If line wr there is the fault being fixed as 0, be then designated as wr (s-a-0), if there is the fault being fixed as 1, be then designated as wr (s-a-1).

◆ Stuck-OpenFault (SOpF, stuck-open fault): a certain unit in RAM, due to the fracture of line, cannot operate on it

◆ TransitionFault (TF, error of transmission): when namely 0 being write to a certain position in RAM, its actual write be 1, or write 1 time, its actual write be 0.

◆ IdempotentCouplingFault(CFid, idempotent coupling fault): when position a certain in RAM to be measured is operated, if numerical value of this write was with originally this numerical value was different, saltus step will be there is, and this saltus step process may have an impact the position adjacent to it, adjacent bit may be caused to become 1 or 0 state.Therefore, CFid is divided into Four types: < ↑ | 0>, < ↑ | 1>, < ↓ | 0>, < ↓ | 1>.

Representing by 0 saltus step to upward arrow is 1, and downward arrow representative is 0 by 1 saltus step.

◆ StateCouplingFault(CFst, state coupling fault): when operating position a certain in RAM to be measured, this position is in certain state, such as, when being in 1 or 0 state, may cause adjacent bit that corresponding change occurs, namely may become 1 or 0 state.Therefore, CFst is also divided into Four types: <1; 1>, <1; 0>, <0; 1>, <0; 0>.

◆ InversionCouplingFault(CFin, inverse coupling fault): when operating a certain position in RAM to be measured, in any case its saltus step, be namely 0 by 1 saltus step or have 0 saltus step to be 1, all can cause the change of the value of adjacent certain.Such as, a certain position initial value in RAM to be measured is 0, and then to its write 1, this time, its adjacent certain just may become 1 from 0, and when writing 0 again to this position, certain adjacent position has just become 0 again by 1 again.Therefore, CFin is divided into two types: < ↑ | x>, < ↓ | x>.Become 1 to upward arrow representative from 0, downward arrow representative becomes 0 from 1.

◆ AddressFault (AF, address fault): when a certain address in RAM to be measured is operated, possible operation be not the address of wishing, and become other address.

◆ Byte_EnableFault(BEF, byte enable mistake): the byte_enable control bit in RAM may be connected, or is fixed as some numerical value 1 or 0.

Summary of the invention

In view of this, the object of the present invention is to provide a kind of method that can improve RAM production defect in the detection integrated circuit of testing efficiency.

The present invention is by the following technical solutions:

Detect a method for RAM production defect, the method comprises the following steps:

1) everybody writes 0 to treat all addresses of testing ram;

Be operand with address in following step, and after this each step enter the test of next address complete the test of current procedures in current address after, until enter the test of next step after traveling through whole RAM, until complete the test of RAM:

2) read the value deposited RAM current address, if contain the position of 1, then termination detection, reports an error; If be entirely 0, then to this address, everybody writes 1, then reads the value that this address is deposited, if contain the position of 0, then termination detection, reports an error; If be entirely 1, then to this address, everybody writes 0, then reads the value that this address is deposited, if contain the position of 1, then termination detection, reports an error; If be entirely 0, then to this address, everybody writes 1;

3) read the value deposited RAM current address, if contain the position of 0, then termination detection, reports an error; If be entirely 1, then to this address, everybody writes 0, reads the value that this address is deposited, if contain the position of 1, then termination detection, reports an error; If be entirely 0, then to this address, everybody writes 1.

As can be seen from the above technical solutions, according to the present invention, realize the test for a rear step based on last testing procedure RAM current address state, need not test at every turn only test a test point, thus need not reset for each RAM and reuse method of testing, efficiency improves greatly.

The method of above-mentioned detection RAM production defect, step 1) to the sequence of operation of step 3) to RAM is from low address to high address all.

The method of above-mentioned detection RAM production defect, also comprises the following steps operated from RAM high address to low address after step 3):

4) read the value that RAM current address is deposited, if contain the position of 0, then termination detection, reports an error; If be entirely 1, then to this address, everybody writes 0;

5) read the value that RAM current address is deposited, if contain the position of 1, then termination detection, reports an error; If be entirely 0, then to this address, everybody writes 1; Then read the value that this address is deposited, if contain the position of 0, then termination detection, reports an error; If be entirely 1, then to this address, everybody writes 0, then the data of the sequence composition according to 1,0 are write this address, read this address, judge the <1|1> defect of CFst, if there is this defect, report an error, otherwise, the data of the sequence composition according to 0,1 are write this address, then order reads this address, judge the <0|0> defect of CFst, if there is this defect, report an error, otherwise, complete the test of this address.

The method of above-mentioned detection RAM production defect, is detecting current RAM, is mating next RAM, arranging width and the degree of depth of test.

Accompanying drawing explanation

Fig. 1 is nine grids test schematic diagram.

Fig. 2 is the structure principle chart of ram test device.

Embodiment

Based in background technology to the analysis of various defect, by the generation of test vector as shown in Figure 2, wherein the former number that writes to RAM current address of test vector is as an input of comparer, reading number and former number, testing corresponding RAM for comparing.

According to the present invention, a complete method of testing can simply use statement to be expressed as follows:

↑write0

↑read0，write1，read1，write0，read0，write1

↑read1，write0，read0,write1

↓read1,write0

↓read0，write1,read1,write0,writedata1,readdata1,writedata2,readdata2

To the operation that upward arrow is from low address to high address, downward arrow is the operation from high address to low address, and 0 represents full 0, and 1 to represent complete 1, data1 be 101010 ..., data2 is 010101 ...Method of testing is divided into quinquepartite, and whole address ram is operated one time by every part representative, therefore operates five times altogether to whole address ram, namely completes test mentioned herein and contain five steps.Nature, can select segmental defect to test.

Therefore, further, a kind of method detecting RAM production defect in integrated circuit, as described in the background section, the integrated level of current chip is more and more higher, and RAM integrated on chip gets more and more, and type is also many, as large classification SRAM, DRAM, there is certain difference in dissimilar RAM, lays particular emphasis on herein and test single RAM.

The method comprises the following steps:

1) to all addresses of RAM, everybody writes 0, if as 16 bit address, is then 16 0, as the degree of depth, always namely as having 65535 addresses, be then exactly 16 × 65535 0;

Here reading should be to the disposable reading of appropriate address, is not that step-by-step is read, then correspondingly with test vector deposits as the number in this address compares, judge whether correctly.Here also can be understood as the problem judging that whether two numbers are consistent, much higher compared to step-by-step reading efficiency.

Thus above-mentioned steps also can be understood like this, test vector coupling is by the sequence be made up of 0 and/or 1, sequence corresponding for current procedures is write as full 0 to current address, read the numerical value sequence in other words deposited this address, compared with the numerical value that writes corresponding in predetermined test vector or sequence, if not identical, show existing defects, report an error, if consistent, then carry out the same class testing of next address.

Based on above description, and in conjunction with the analysis of background technology part relative drawbacks, front several step is analyzed as follows:

◆ full 0 is write to whole RAM.

◆ first Part II in other words the 2nd step is read, the order read can mate the order write, be consistent, as by low address, first 0 of first step write is read, if read data in promising 1 position, just illustrate that this position may be fixed as 1, namely there is SAF defect, or cannot write it because line is disconnected, namely there is SOpF defect, or error of transmission, when namely writing 0, what reality write is 1, namely there is TF defect, or due to left and right, above, the a certain Influential cases of diagonally opposing corner is in 0 state above, tested point is changed, namely there is the <0 in CFst defect, 1>.

Accept epimere, if reading is 0 entirely, more then 1 is read to current address write 1; if there is the position of 0 in sense data, according to analysis above, may exist in SAF be fixed as 0 defect; or SOpF defect, or TF defect, or the <0 in CFst; 0>, or because horizontal Influential cases occurs by the saltus step of 0 to 1, cause the change of tested point numerical value, namely exist < in CFid defect ↑ | 0>, same or due to horizontal Influential cases exist < in CFin defect ↑ | x>.

Accept epimere, if what read is 1 entirely, and then then 0 is read to current address write 0, if there is the position of 1 in the data that this time reads, may measure < in new defect CFid defect ↓ | 1>, certainly this is caused by horizontal Influential cases, or exist < in CFin defect ↓ | x>.Finally more entirely 1 is write to this address.Then next address is repeated to the operation of Part II, analyzing influence point is on the impact of tested point in turn.

Nine grids as shown in Figure 1, are China's calligraphy history is faced note to write imitative a kind of boundary lattice originally, cry again " nine grids "; Similar structure is also existed for memory cell matrix, and may there is certain impact in the logical circuit of consecutive storage unit, will produce structure as shown in Figure 1.

By that analogy, operation part below be the same above, can analyze according to the simple analytical approach introduced above the method for testing provided is what how to realize the covering of RAM basic test point.

What use statement performance is the method for testing of complete all test points of covering, but a method of testing can be tested segmental defect, but not to all.

As shown in Figure 2, be the one-piece construction block diagram of whole ram test, total block diagram is divided into three parts: controller, test vector generator and comparer.The effect of controller is the read-write operation of control RAM, in RAM read-write process, controls the change of address, realizes the Test coverage to whole RAM.Write operation writes in RAM to be measured by the test vector that test vector generator generates, and ensures correctness and the accuracy of data write.Read operation is come by the data reading in write RAM to be measured, gives the comparatively validate that comparator module carries out data, and whole read procedure will ensure the correctness of address and read the accuracy of data, thus realizes the test job to RAM to be measured.

Test vector generator functions of modules produces the test vector for testing ram, and its function is the demand that the test vector produced will ensure method of testing, and guarantee to test required defect point.

Comparer is compared the data read out in RAM to be measured and the data originally write, with determine to be measured in RAM whether there is flaw, proving installation will be tested for different RAM, and different RAM can be different, therefore, its structure should have the adaptability of wide area.The specifically degree of depth of RAM, namely address number can not be identical, when the data of therefore writing and reading compare, to make corresponding adjustment according to the width of RAM to be measured (bit wide) and the different of the degree of depth (address number).When there is flaw in some in RAM to be measured, stop the test job to RAM immediately, and draw high bist_fail signal reporting errors, if when the current data read and the data consistent of write, continue to perform test job below, draw high bist_done signal and report that the whole test job of current RAM completes.

Lay particular emphasis on herein and test the mode of whole defect all standing, the data of RAM write in step before accepting current procedures, improve the efficiency of test.

In the methods described above, adopt step 1) to be all the methods of operating from low address to high address to the order of step 3) to the write operation of RAM and read operation, all addresses of traversal RAM, operation relatively simply, also facilitates the expansion of concurrent testing.On the other hand, as shown in Figure 1, from low address to high address, such high address is current is constant, low address takes the lead in changing, can measure address change compared with current address to the impact of high address like this, relating in following content from high toward low, is the impact seeing that the change of high address changes low address.

Therefore, after step 3), also comprise the following steps operated from RAM high address to low address:

1. after step 3), also comprise the following steps operated from RAM high address to low address:

When writing and read data, according to the respective test width of the different set of the hierarchy structure of RAM on same chip and the degree of depth, width here refers to bit wide, as 16,32 or 64.

Obviously, before test, the degree of depth of RAM and width are known.

Further, in test process, mate width and the degree of depth that current RAM to be tested adjusts test.We understand, as long as all RAM in a chip have one to have product defects, just should scrap this chip, from test angle, if RAM existing defects in some tests, ought to just scrap whole chip.Use said method effectively can improve testing efficiency, the generation of test vector is convenient in the test based on said method.

Classic method: the method for testing of employing once can not survey whole test points of full RAM, often need to change test vector, repetition measurement method for testing of laying equal stress on, will survey entirely basic test point like this, and total cycle of needs will be relatively long, and the time of test also extends relatively.

Can find out according to said method: the method for testing of employing once can survey whole test points of full RAM, do not need to reuse method of testing, relative classic method, complete the test of the whole test point of whole RAM, shorten whole test period and test duration, moreover, this method also add Byte_EnableFault(BEF) test, so relative classic method, adds test point, makes test more comprehensive

Ying Zhi, along with the development of packaging technology, the production defect of current RAM compares less, and most tests can both complete smoothly.Obviously, the mode once having surveyed all production defects more effectively can improve testing efficiency.

Claims

1. detect a method for RAM production defect, it is characterized in that, the method comprises the following steps:

1) everybody writes 0 to treat all addresses of testing ram;

3) read the value deposited RAM current address, if contain the position of 0, then termination detection, reports an error; If be entirely 1, then to this address, everybody writes 0, reads the value that this address is deposited, if contain the position of 1, then termination detection, reports an error; If be entirely 0, then to this address, everybody writes 1;

Step 1) to the sequence of operation of step 3) to RAM is from low address to high address all;

The following steps operated from RAM high address to low address are also comprised after step 3):

2. the method for detection RAM production defect according to claim 1, is characterized in that, detecting current RAM, mating next RAM, arrange width and the degree of depth of test.