substantial fault pairs at-a-time (sfpat): an automatic diagnostic pattern generation method

Jing Ye1,2, Xiaolin Zhang1,2, Yu Hu1, and Xiaowei Li1

1Key Laboratory of Computer System and ArchitectureInstitute of Computing Technology

Chinese Academy of Sciences2Graduate University of Chinese Academy of Sciences

Substantial Fault Pairs at-A-Time (SFPAT):An Automatic Diagnostic Pattern

Generation Method

2

Motivation

Fault Diagnosis Quality

Efficiency ofDiagnosis Method

Distinguishability of Used PatternsDistinguish as ManyFault pairs as possibleFew More PatternsThan Test Patterns

3

Outline Key Observation

• Distinguishability of 1-detect compressed Test Patterns• Distinguishability of N-detect Test Patterns

Related Work Proposed Diagnostic Pattern Generation Method

• Diagnostic Pattern Generation Method Overview• Circuit Transformation and Fault List Creation• Diagnostic Pattern Generation Flow

Experimental Result• Experimental Setting

4

Distinguishability of 1-Detect Compressed Test Patterns Experiment Setting

• ISCAS’89 benchmark circuits• 1-detect compressed test patterns (TetraMax Ver.A-2007.12)

Fault Pairs Classification

two faults in the fault pair

are in the same FFR.

FP1 typetwo faults in the fault pair are in different FFRs but

with the same observation points.

FP2 typetwo faults in the fault pair are in different FFRs but with at least one different

observation points.

FP3 type

abcd

e

fg

h

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Fanout Free Region (FFR)

Key Observation

q p

q p

q p

p

5

Percentage of FP3 type fault pairs among all the fault pairs Percentage of indistinguishable FP3 type fault pairs among all the indistinguishable fault pairs


0%10%

20%

30%

40%

50%

60%

70%80%

90%100%


AVERAGE



0%

10%

20%

30%

40%50%

60%

70%

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90%

100%




0%10%

20%

30%

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100%




0%10%

20%30%

40%50%60%

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0%10%20%30%40%50%60%70%80%90%

100%


FP3 type

FP2 type

FP1 type

Distinguishability of 1-Detect Compressed Test PatternsKey Observation

Percentage of FPi-type fault pairs among all the fault pairs

Percentage of indistinguishable FPi-type fault pairs among all

the indistinguishable fault pairs

FP3 type

FP2 type

FP1 type

6



0%10%

20%30%

40%50%60%

70%80%

90%100%


AVERAGEabcd

e

fg

h

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q


FP1 type fault pairs• Two faults in the fault pair are in the same FFR

FP2 type fault pairs• Two faults in the fault pair are in different FFRs

but with the same observation points FP3 type fault pairs

• Two faults in the fault pair are in different FFRs but with at least one different observation point

FP1 > FP2 > FP3‘>’ : harder to be distinguished

7



0%10%

20%30%

40%50%60%

70%80%

90%100%


AVERAGEabcd

e

fg

h

i

j

m

n p

q


FP1 type fault pairs• Two faults in the fault pair are in the same FFR

FP2 type fault pairs• Two faults in the fault pair are in different FFRs

but with the same observation points FP3 type fault pairs

• Two faults in the fault pair are in different FFRs but with at least one different observation point

FP1 > FP2 > FP3‘>’ : harder to be distinguished

+

8

N-detect test pattern• A fault may be detected for multiple times in different ways.

Distinguishability of N-Detect Test PatternsKey Observation

0

5

10

15

20

25

30

35

40

45

50

55

s208 s1196 s1423 s1488 s1494 s5378

Num. of indistinguished fault pairs

1-detectcompressed

1-detect 2-detect 3-detect 4-detect

FP1 type fault pairspat

Flt.1 Flt.2

9

Related Work Test elimination process of modifying test patterns

• [I. Pomeranz, S. M. Reddy TCAD2000]• [I. Pomeranz, S. M. Reddy ETS2007]

Exclusive test pattern generation• [V. D. Agrawal, D. H. Baik, et al. ICVD2003]

Pattern generation for fault-tuple modeled faults• [N. K. Bhatti, R. D. Blanton ITC2006]

Integer linear program formulation• [M. A. Shukoor, V. D. Agrawal ETS2009]

Pattern distinguishability and N-detect patterns• [Z. Wang, M. Marek-Sadowska, et al. ICCD2003]

Pattern reordering algorithm for truncated fail data• [C. Gang, S. M. Reddy, et al. DAC2006]

10

Diagnostic Pattern Generation Method OverviewProposed Diagnostic Pattern Generation Method

+ =>

Transferred circuit netlist and fault list=>

ATPG tool=>

More indistinguished fault pairs?Yes!

No!

Original circuit netlist Target fault list

END

pat.A pat.B pat.C

Flt.1 flt.2 flt.3 flt.4 flt.5

Consider Substantial Fault Pairs at-A-Time

11


+ =>


ATPG tool=>


No!


END

pat.A pat.B pat.C



12


+ =>


ATPG tool=>


No!


END

pat.A pat.B pat.C



13


+ =>


ATPG tool=>


No!


END


Reduce noiseLower power

Compress patterns

Cont.

14

Proposed Diagnostic Pattern Generation Method

Circuit Transformation and Fault List Creation Miter circuit

• Miter circuit is a circuit consisting of two modified duplication D1 and D2 of the original circuit.

• Different connection of D1 and D2 is proposed in previous works. S-fault

• The pattern which can detect a S-fault in the transformed circuit can distinguish its related fault pair in the original circuit.

Example• Stuck-at v fault at l: l/v.• We will work on other fault models in the future.• Distinguish the fault pair (a/1,c/1) and the fault pair (b/1,d/1).

abcd

egh

ij

m

nf

15

abcd

egh

ij

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nf


Circuit Transformation and Fault List Creation

abcd

egh

ij

m

nf

abcd

e

D1

gh

ij

m

n

abcd

f

e

D2

gh

ij

m

nf

Target fault pair• (a/1,c/1)• (b/1,d/1)

SA1-module• ‘out’ = ‘sel’ | ‘in’

•

MU

XS0S1

1in

sel

out

SA1

16



abcd

e

D1

gh

ij

m

n

abcd

ABCD

f

e

D2

gh

ij

m

nf



•

MU

XS0S1

1in

sel

out

SA1

17

abcd

e

D1

gh

ij

m

n

abcd

ABCD M

N

f

e

D2

gh

ij

m

nf



SA1

SA1

SA1

SA1

abcd

e

D1

gh

ij

m

n

abcd

ABCD M

N

SA1

SA1

SA1

SA1

f

e

D2

gh

ij

m

nf



•

MU

XS0S1

1in

sel

out

SA1

18

abcd

e

D1

gh

ij

m

n

abcd

ABCD M

N

SA1

SA1

SA1

SA1

sel1 sel2

f

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D2

gh

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0 1 S-fault• sel1/1 – (a/1,c/1)• sel2/1 – (b/1,d/1)



•

MU

XS0S1

1in

sel

out

SA1

19

abcd

e

D1

gh

ij

m

n

abcd

ABCD M

N

SA1

SA1

SA1

SA1

sel1 sel2

f

e

D2

gh

ij

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nf



0 1

FAULT-FREE

FAULT-FREE

0

0

S-fault• sel1/1 – (a/1,c/1)• sel2/1 – (b/1,d/1)



•

MU

XS0S1

1in

sel

out

SA1

20

abcd

e

D1

gh

ij

m

n

abcd

ABCD M

N

SA1

SA1

SA1

SA1

sel1 sel2

f

e

D2

gh

ij

m

nf



0 1

INJECT a/1

INJECT c/11




•

MU

XS0S1

1in

sel

out

SA1

21

abcd

e

D1

gh

ij

m

n

abcd

ABCD M

N

SA1

SA1

SA1

SA1

sel1 sel2

f

e

D2

gh

ij

m

nf



Fault in original circuit• Constrain the value of sel to 0




•

MU

XS0S1

1in

sel

out

SA1

INJECT h/1

FAULT-FREE

0

0

22

Some of faults arecertain distinguished if they are detected.(1) All the faults in original circuits.(2) S-faults of FP1 type fault pairs which may not be distinguished when they are detected.


Diagnostic Pattern Generation Flow

+ =>=>

ATPG tool=>


No!

Original circuit netlist

END

FP1 type fault pairsOriginal circuit netlist + =>

Transferred circuit netlist and fault list=>=>

Indistinguished fault pairs

Transferred circuit netlist and S-fault list

ATPG tool

+ =>


ATPG tool=>


No!


END

FP1 > FP2 > FP3

23

+ =>=>

ATPG tool=>


No!


END





ATPG tool




+ =>=>

ATPG tool=>


No!


END





ATPG tool

Is a fault pair distinguished if both faults are detected?(a/1,b/1) (a/1,e/0) (a/1,c/1) (a/1,d/1) (a/1,f/0) (a/1,g/1) (a/1 g/0)

Yes Yes No No Yes Yes Yes(b/1,e/0) (b/1,c/1) (b/1,d/1) (b/1,f/0) (b/1,g/1) (b/1,g/0) (e/0,c/1)

Yes No No Yes Yes Yes Yes(e/0,d/1) (e/0,f/0) (e/0,g/1) (e/0,g/0) (c/1,d/1) (c/1,f/0) (c/1,g/1)

Yes Yes Yes Yes Yes Yes Yes(c/1,g/0) (d/1,f/0) (d/1,g/1) (d/1,g/0) (f/0, g/1) (f/0,g/0) (g/1,g/0)

Yes Yes Yes Yes Yes Yes Yes

abcd

egh

ij

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24




+ =>=>

ATPG tool=>


No!


END





ATPG tool

(1) No patterns can distinguish a target fault pair.(2) ATPG tool cannot achieve 100% S-fault coverage.

BREAKSAT tool

25

Experimental SettingExperimental Result

Benchmark circuit• ISCAS’89• ITC’99

Test Pattern• TetraMax Ver.A-2007.12• 1-detect compressed test patterns

26

Experimental DataExperimental Result

Circuit s5378 s9234 s13207 s15850 s35932 s38417 s38584

Stuck-at faults 4563 6473 9664 11336 35110 31015 34797

Test patterns 123 156 264 128 24 111 144

Indistinguished fault pairs 593 1621 2276 2971 14438 3850 3242

FP1 typeS-faults 18006 24370 42099 26584 18924 34057 67871

Diagnostic patterns 124 164 273 146 28 118 155

Remaining indistinguished

S-faults 578 1552 2062 2909 13123 3673 2808

Diagnostic patterns 20 71 5 26 3 19 13

Total diagnostic patterns 144 235 278 172 31 137 168Fault pairs which cannot be

distinguished by any patterns 523 1229 2043 2801 12893 3372 2696

The number of S-faults is mainly determined by the circuit structure

The number of S-faults becomes much smaller

27

Comparison with Previous WorkExperimental Result

s5378 s9234 s13207 s15850 s359320

50

100

150

200

250

300

350

Number of diagnostic patterns in [12] Number of diagnostic patterns in this work

Number Percentage

Number of test patterns in [12] Number of test patterns in this work

30%

40%

50%

60%

70%

80%

90%

100%

Percentage of distinguished fault pairs under diagnostic patterns among indistinguishable fault pairs under test patterns [12] this work

[12] I. Pomeranz and S. M. Reddy, "Diagnostic Test Generation Based on Subsets of Faults," Proc. of European Test Symposium (ETS), pp. 151-158, 2007.

Comparison with [12]• ISCAS’89: almost the same for the small circuits• ITC’99: different version of benchmark circuits

28

Comparison with Previous WorkExperimental Result

[12] I. Pomeranz and S. M. Reddy, "Diagnostic Test Generation Based on Subsets of Faults," Proc. of European Test Symposium (ETS), pp. 151-158, 2007.

Comparison with [12]

s5378 s9234 s13207 s15850 s359320

50

100

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350


Number Percentage


30%

40%

50%

60%

70%

80%

90%

100%


s5378 s9234 s13207 s15850 s359320

50

100

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350


Number Percentage


30%

40%

50%

60%

70%

80%

90%

100%


s5378 s9234 s13207 s15850 s359320

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Number Percentage


30%

40%

50%

60%

70%

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100%


s5378 s9234 s13207 s15850 s359320

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Number Percentage


30%

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70%

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s5378 s9234 s13207 s15850 s359320

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Number Percentage


30%

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90%

100%


Number of diagnostic patterns in [12]

Number of test patterns in [12]

About 90% of distinguished fault pairs under diagnostic patterns

among indistinguished fault pairsunder test patterns in [12]

Number of diagnosticpatterns in this work

Number of testpatterns in this work

100% in this work

29

ConclusionDistinguishability of patterns are important !

Distinguishability of 1-detect compressed test patterns• FP1 > FP2 > FP3

Miter-circuit and S-fault• The pattern which can detect a S-fault in the miter-circuit can

distinguish its related fault pair in the original circuit.• There is no need to modify the ATPG tool, and the functions of

ATPG tool can also be applied.

Thank You for Your Attention !

Any Questions?

substantial fault pairs at-a-time (sfpat): an automatic diagnostic pattern generation method

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