# US 10,482,989 B1 · Dynamic diagnostics analysis for memory built-in self-test

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- Number: US 10,482,989 B1
- Document ID: US10482989B1
- Status: Granted
- Kind: B1
- Application number: 15/903,916
- Filed: 2018-02-23
- Granted: 2019-11-19
- Earliest claimed: 2018-02-23
- Applicants: Cadence Design Systems, Inc.
- Inventors: Steven Lee Gregor; Puneet Arora; Norman Robert Card
- Web page: https://patentgrep.com/patent/US10482989B1

## CPC

- G11C 29/38: Response verification devices
- G11C 29/56008: {Error analysis, representation of errors}
- G11C 29/44: Indication or identification of errors, e.g. for repair
- G11C 29/4401: {for self repair}
- G11C 29/72: {with optimized replacement algorithms}
- G11C 2029/5604: {Display of error information}
- G11C: STATIC STORES (semiconductor memory devices H10B)

## Abstract

Systems and methods disclosed herein provide for improved diagnostics for memory built-in self-test (“MBIST”). Embodiments provide for a two-pass diagnostic test of the target memory, wherein, in the first pass, a data compare unit provides clock cycle values associated with detected mis-compares to a tester, and, in the second pass, the data compare unit extracts data vectors associated with the clock cycle values. Embodiments further provide for a bit fail map report that is generated based on the extracted data vectors.

## Claims

### Claim 1

A memory built-in self-test (“MBIST”) diagnostics system, comprising:
a memory, wherein the memory is tested with an algorithm for a plurality of passes;
a data compare unit;
a tester; and
a processor, wherein:
during a first pass of the test, the data compare unit is configured to provide, to the tester, a clock cycle associated with a word of the memory including at least one mis-compare,
during at least a second pass of the test, the data compare unit is further configured to (i) extract contents of the word based on the corresponding clock cycle and (ii) provide the extracted contents of the word to the tester, and
the processor is configured to generate a bit fail map report based on the extracted contents of the word, wherein the bit fail map report includes information associated with the at least one mis-compare.

### Claim 2 (depends on 1)

The diagnostics system of claim 1, wherein the clock cycle associated with the word and the extracted contents of the word are provided to the tester via a test access method.

### Claim 3 (depends on 2)

The diagnostics system of claim 2, wherein the test access method is one of a Joint Test Action Group (“JTAG”) interface and a direct access interface.

### Claim 4 (depends on 1)

The diagnostics system of claim 1, wherein the data compare unit includes a data vector, wherein the contents of the word are extracted from the data vector.

### Claim 5 (depends on 1)

The diagnostics system of claim 1, wherein the tester negatively adjusts the clock cycle.

### Claim 6 (depends on 5)

The diagnostic system of claim 5, wherein the extracted contents of the word are associated with the adjusted clock cycle.

### Claim 7 (depends on 5)

The diagnostics system of claim 5, further comprising:
a simulator, wherein the simulator is configured to test the memory with the algorithm in a simulation environment.

### Claim 8 (depends on 7)

The diagnostics system of claim 7, wherein the simulation environment test is performed during one of (i) before the algorithm test for the plurality of passes, (ii) concurrent with the algorithm test for the plurality of passes, and (iii) after the algorithm test for the plurality of passes.

### Claim 9 (depends on 7)

The diagnostics system of claim 7, wherein the simulator is further configured to (i) receive the adjusted clock cycle, (ii) extract information from the simulation environment based on the adjusted clock cycle, and (iii) store the extracted simulation environment information, the adjusted clock cycle, and the extracted contents of the word in a dump file.

### Claim 10 (depends on 9)

The diagnostics system of claim 9, wherein the bit fail map report is generated with an analysis software test, wherein the analysis software test receives, as inputs, the dump file, a pattern control file, a plurality of mapping files, a test definition file, and a default algorithm file.

### Claim 11 (depends on 10)

The diagnostics system of claim 10, wherein the bit fail map report is generated by correlating the dump file, the pattern control file, the plurality of mapping files, the test definition file, and the default algorithm file.

### Claim 12 (depends on 1)

The diagnostics system of claim 1, further comprising:
at least one other memory, wherein the other memory is tested with another algorithm for another plurality of passes, wherein the at least one other memory is tested concurrently with the memory.

### Claim 13 (depends on 1)

The diagnostics system of claim 1, further comprising:
at least one sequence iterator unit, wherein the at least one sequence iterator unit is configured to (i) generate read command and address instructions associated with the algorithm to provide to the memory and (ii) provide expected read data associated with the algorithm to the data compare unit.

### Claim 14 (depends on 13)

The diagnostics system of claim 13, wherein the data compare unit is configured to (i) compare the expected read data with an output of the memory and (ii) provide a result of the comparison to a data vector.

### Claim 15 (depends on 13)

The diagnostics system of claim 13, further comprising:
an algorithm memory unit, wherein the algorithm memory unit provides the algorithm to the at least one sequence iterator unit.

### Claim 16

A diagnostics method for memory built-in self-test (“MBIST”), the method comprising:
testing a memory with an algorithm for a plurality of passes, wherein:
during a first pass of the test:
providing, with a data compare unit, a clock cycle associated with a word of the memory including at least one mis-compare to a tester,
during at least a second pass of the test:
extracting, with the data compare unit, contents of the word based on the corresponding clock cycle, and
providing, with the data compare unit, the extracted contents of the word to the tester; and
generating, with a processor, a bit fail map report based on the extracted contents of the word, wherein the bit fail map report includes information associated with the at least one mis-compare.

### Claim 17 (depends on 16)

The diagnostics method of claim 16, wherein the clock cycle is negatively adjusted by the tester, wherein the extracted contents of the word are associated with the adjusted clock cycle.

### Claim 18 (depends on 17)

The diagnostics method of claim 17, further comprising:
simulating, with a simulator, a simulation environment test of the memory with the algorithm, wherein the simulation environment test is performed during one of (i) before the algorithm test for the plurality of passes, (ii) concurrent with the algorithm test for the plurality of passes, and (iii) after the algorithm test for the plurality of passes.

### Claim 19 (depends on 18)

The diagnostics method of claim 18, further comprising:
receiving, with the simulator, the adjusted clock cycle;
extracting, with the simulator, information from the simulation environment based on the adjusted clock cycle; and
storing, with the simulator, the extracted simulation environment information, the adjusted clock cycle, and the extracted contents of the word in a dump file.

### Claim 20 (depends on 16)

The diagnostics method of claim 16, further comprising:
testing at least one other memory with another algorithm for another plurality of passes, wherein the at least one other memory is tested concurrently with the memory.