the state-of-the-art test compression and test response …¹€홍식.pdf · 2008-11-19 · nano...

The State-of-the-Art Test Compression and Test Compression and Test Response Compaction Techniques

2008.11.152008 테스트 기술 워크샵

Hong-Sik KimHong-Sik Kim

Contents

IntroductionTest Stimulus CompressionTest Response CompactionIndustrial PracticeConclusion

Computer Systems & Reliable SoC Lab. 2

Test Data Increase

Increase in the number of test patternsIncreasing number of embedded IP cores

Increasing number of target fault models for DSM t h l itechnologies

Transition fault testing requires 3~5 times more test patterns than stuck at fault testing

Newer chips with more pins and functionality but older ATE equipmentfunctionality but older ATE equipment

Less test channels

Not enough ATE memoryNot enough ATE memory

Low-cost ATE : reduced pin count test

Keep do n test cost


Keep down test cost

Test Data Volume vs Technology Introduction

TTest Dataa Size

Gate Size


Source : Blyler, Wireless System Design, 2001

Test Quality Improvement for Nano Technology IntroductionNano Technology

Multiple detectShown to improve test quality in 200K production run experiment

DFM-oriented testExtractions from physical p ydatabase (such as Calibre)For example, deterministic bridge fault modelfault model

Timing aware testTiming aware testUse SDF to test longest paths


Test Data Volume vs Technology Introduction

TTest Dataa Size

Technology

Source : www.elecdesign.com


Why Test Compression? Introduction

TestTestQuality

Requirement

180nm 130nm 90nm


Full Scan VS Compressed Scan Introduction


Test Data Compression Introduction

AdvantageComplete set of ATPG test Complete set of ATPG test patterns can be appliedCompatible with the

ti l d i l d convectional design rules and test generation flow for scan testing

fiBenefitsReduce amount of test data

Life cycle of older tester with ylimited memory is extended

Test time reduces for a given test data bandwidth

With test compression, larger number of scan chains can be used


Test Data Compression Introduction

Test (Stimulus) CompressionCode-based compressionCode based compressionLinear-decompression based schemeBroadcast scan

Test Response CompactionSpace compactionTime compactionMixed one


Introduction

Test Stimulus CompressionTest Response CompactionIndustrial PracticeConclusion


Categories of TC Test StimulusCompression

Code-based SchemesTraditional coding algorithm

Compression

Traditional coding algorithmEntropy coding

Linear-Decompression-based SchemesLinear-Decompression-based SchemesCombinational

XOR networksSequential (Static/Dynamic)Sequential (Static/Dynamic)

LFSR reseeding

Broadcast Scan Based SchemesBroadcast-Scan-Based SchemesTraditional

Scan forest/Illinois scanR fi blReconfigurable

Static/Dynamic


Code-Based TC Test StimulusCompression

Dictionary coding

Compression

fixed to fixed

Huffman codingfi d t i blfixed to variable

Run-length codingvariable to fixedvariable to fixed

Golomb codingvariable to variablevariable to variable

Arithmetic codingfixed to variableed o a ab e


Test StimulusCompression

Code-Based TC

Run-length coding based test compression

Compression

A.Jas et al, “Test Vector Decompression via Cyclic Scan Chains and its application to Testing Core-Based Designs,” ITC, 1998g , ,



Code-Based TC

Golomb coding based test compression

Compression

A.Chandra et al, “System-on-a-Chip Test-Data Compression and Decompression Architecture Based on Golomb Codes,” IEEE Trans. on CAD, 2001, ,



Code-Based TC

Dictionary coding

Compression

S.M.Reddy et al, “On Test Data Volume Reduction for Multiple Scan Chain Designs,” VTS 2002



Code-Based TC

Selective HC based test compression

Compression

A.Jas et al, “An Efficient Test Vector Compression Scheme Using Selective Huffman Coding,” IEEE Trans. on CAD, 2003,



Linear Decompression Based Scheme

Compress test data by using linear equation d l

CompressionScheme

and solver

Cl ifi iClassificationCombinational linear de-compressorSequential linear de compressorSequential linear de-compressor

Fixed lengthVariable length





CompressionScheme

and solver





CompressionScheme

and solver

X1 X2 X3 X4 X5 X6 X7 X8 X9 X100 0

1 01 0

01

0111

110 1 1 1 0 0 0 x x 1




Combinational Linear DecompressionI.Bayraktaroglu et al, “Concurrent Application of Compaction and

CompressionScheme

y g , pp pCompression for Test Time and Data Volume Reduction in Scan Design,” IEEE Trans on Computers, 2003




LFSR Reseeding SchemeB Koenemann “LFSR-coded Test Patterns for Scan

CompressionScheme

B.Koenemann, LFSR coded Test Patterns for Scan Designs,” ETC, 1991

00xxx0xx0111

C1

C2

Test Cubes

+

a2 a1 a0 c5 c4 c3 c2 c1 c0

x1x0x100xxx0

C0

C1

a0a1a2a0+a2a0+a1 +a2

a0+a1

a1=1a0=0a0+a2=0a0+a1 =1

A system of linear equations

a1=1a2=0

Seed for C0




Ring GeneratorG Mrugalski et al “Ring Generators-New Devices for

CompressionScheme

G. Mrugalski et al, Ring Generators New Devices for Embedded Test Applications,” IEEE Trans. on CAD, 2004




Variable rank LFSR with BFHong-Sik Kim et al, “Increasing Encoding Efficiency of LFSR

CompressionScheme

g , g g yReseeding-based Test Compression,” IEEE Trans. on CAD, 2006



Broadcasting

Concept

Compression

Input the same test data to multiple scan chains

V i TC S h b d B dVarious TC Schemes based BroadcastILLINOIS scanScan forestScan forestMulticast based TC



Broadcasting

Concept

Compression

Input the same test data to multiple scan chains

Force ATPG tool to generatepatterns for broadcast scan



Broadcasting

ISA (Illinois scan architecture)

Compression

I.Hamzaoglu et al, “Reducing Test Application Time for Full Scan Embedded Cores,” FTCS, 1999



Broadcasting

Scan forestD Xiang et al “Reconfigured Scan Forest for Test Application

Compression

D.Xiang et al, Reconfigured Scan Forest for Test Application Cost, Test Data Volume and Test Power Reduction,” IEEE Trans. on Computers, 2007

Scan forest is constructed based on structural analysisReduced number of scan l f d th leaf decreases the number of XOR gate in response compactorReduce both test data Reduce both test data volume and power consumption



Broadcasting

Multicast based TCD Xiang et al “Reconfigured Scan Forest for Test Application

Compression

D.Xiang et al, Reconfigured Scan Forest for Test Application Cost, Test Data Volume and Test Power Reduction,” IEEE Trans. on Computers, 2007


Contents

IntroductionTest Stimulus Compression

Test Response CompactionIndustrial PracticeConclusion


Categories of TC Test ResponseCompression

Space compactionReducing the number of output bit size

Compression

Reducing the number of output bit size

Time compactionReducing the number of output response patternsReducing the number of output response patterns

Mixed space and time compaction


Response Compaction Issues Test ResponseCompression

Aliasing problem

Compression

X propagationManay sources of unknown X’s in output response data

Unmodeled ATPG logics : RAM’s mixed signal logic black boxes Unmodeled ATPG logics : RAM s, mixed signal logic, black boxes etcUninitialized memory elements (non scaned FF’s)Floating tri-statesgMulti-cycle pathsEtc


X propagation Problem Test ResponseCompression

Conventional ScanEasy to handle X values in test response by masking them on

Compression

y p y gtester

Logic BIST and test response compactionLogic BIST and test response compactionX’s corrupt final signaturePrevents observation of other scan cellsOutput compression ratios and ATPG results are degreated by Output compression ratios and ATPG results are degreated by the capture of unknown value

1 1 0 0 1 X 1 0MI0 1 1 0 X 1 0 0

0 1 1 1 0 0 0 X

ISR


0 1 1 1 0 0 0 X

Handling X’s Test ResponseCompression

X-Bounding (X-blocking)Insert DFT to prevent X’s from propagating to output

Compression

p p p g g p

X-tolerant compactorMake compactor resilient to one or several X’s propagated to Make compactor resilient to one or several X s propagated to the compactor

X MaskingX-MaskingMask X’s at the input to compactorMask data required


X-Tolerant TRC Test ResponseCompression

X-CompactS.Mitra et al, “X-Compact: An Efficient Response Compaction Technique ” IEEE Trans on CAD 2004

Compression

Technique, IEEE Trans. on CAD, 2004

C bi ti l tCombinational compactorTolerates one X per scan sliceDetects 1 2 or any odd errors


Detects 1, 2, or any odd errorsCorrupted outputs will be masked on tester

X-Tolerant TRC Test ResponseCompression

X-CancelingN.A.Touba,”X-canceling MISR – New Approach for X-Tolerant Output Compaction ” ITC 2007

Compression

Output Compaction, ITC, 2007


X-Masking TRC Test ResponseCompression

X-MaskingX’s can be masked off right before the

Compression

X s can be masked off right before the response compactorMask data is required to indicate when the Mask data is required to indicate when the masking should take placeMask data can be compressedMask data can be compressed

LFSR reseeding, run-length coding



Masking compression based on HCG.Zeng et al, “X-tolerant test data compression for SOC

Compression

g , pwith Enhanced Diagnosis Capability,” IEICE IS, 2005



X-BlockS.Wang et al, “X-Block: An Efficient LFSR Reseeding-

Compression

g , gbased Method to Block Unknowns for Temporal Compactors,” IEEE Trans on Computers, 2008


Contents

IntroductionTest Stimulus CompressionTest Response Compaction

Industrial PracticeConclusion


Mentor Graphics IndustrialPractice

Embedded Deterministic Test (EDT)

Practice

TestKompressFirst commercially available on-chip test compression productproduct


SynTest IndustrialPractice

Virtual scanTestKompress

Practice

TestKompressFirst commercial product based on the broadcast scan scheme using combinational logic for pattern decompression


Synopsys IndustrialPractice

Adaptive scan

Practice

DFTMAX


Summary of Commercial Solutions

IndustrialPracticeSolutions Practice

Industrial Practice Stimulus Compression

Response Compression

EDT (Mentor) Ring generator XOR tree

Virtual Scan Combinational logic Virtual Scan (Syntest)

Combinational logic network (broadcast) XOR tree

Combinational MUX DFTMAX (Synopsys) Combinational MUX network (broadcast) XOR tree


Conclusion

Test CompressionEffective method to reduce test data volume and test application time

Good solution for test cost reduction

Easy to implement and capable of producing high-lit t tquality tests

Part of design flow


the state-of-the-art test compression and test response …¹€홍식.pdf · 2008-11-19 · nano...

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