RAM-BIST-BISD-jfli
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Transcript RAM-BIST-BISD-jfli
Built-In Self-Test/Self-Diagnosis
for RAMs
Jin-Fu Li
Advanced Reliable Systems (ARES) Lab.
Department of Electrical Engineering
National Central University
Jhongli, Taiwan
Outline
Introduction
Fault Models and Test Algorithms
Fault models
Test Algorithms
Memory BIST/BISD Design
BIST Design
BISD Design
Memory Diagnosis
Fault Diagnosis
Defect Diagnosis
Jin-Fu Li
ARES Lab. EE, NCU
2
Introduction
Modern system-on-chip (SOC) designs typically
consist of hundreds of memories
Memories usually dominate the chip area
Furthermore, memories are designed with the
aggressive design rules such that they are prone
to defects
Thus the memory yield heavily impacts the SOC
yield
Increasing memory yield can significantly increase
the SOC yield
Yield-enhancement techniques for memories
Diagnosis & repair
Jin-Fu Li
ARES Lab. EE, NCU
3
SOC Yield
Yield of an SOC
YS YM YL
Improve the yields of memories can drastically increase
the yields of SOCs
For example, UltraSparc chip yield
Source: R. Rajsuman, IEEE
D&T, 2001
Jin-Fu Li
ARES Lab. EE, NCU
4
Yield Learning Curve
Yield
Diagnosis/repair
Repair
Mature
phase
Early
phase
Intermediate
phase
Jin-Fu Li
ARES Lab. EE, NCU
Time
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Testing and Repair of RAMs in SOCs
16-core SPARC (Oracle)
DFT features:
1. Scan test + test
compression
2. Programmable memory
built-in self-test (MBIST)
+ repair
3. SerDes internal and
external look-back tests
Jin-Fu Li
ARES Lab. EE, NCU
Niagara2 (Sun)
DFT features:
1.32 Scans + ATPG
2.BIST for arrays
3.….
POWER6 (IBM)
DFT features:
1.Logic BIST
2.BIST for arrays
3.BISR for arrays
4.…
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Fault Models and Test Algorithms
Conclusions
Undoubtedly, 3D RAM will be one pioneer
product using 3D integration technology
Some differences exist between a 2D RAM and a
3D RAM with TSVs
Those differences incur some challenges on the
testing and repair of 3D RAMs
Effective testing and repair techniques thus are
imperative for the production of 3D RAMs
Due to the uncertainty of a 3D RAM
DFT/DFY/DFR techniques with the feature of
adaptability is one main trend
Jin-Fu Li
ARES Lab. EE, NCU
8