IEEE transactions on computer-aided design of integrated circuits and systems : a publication of the IEEE Circuits and Systems Society

Modern electronics testing has a legacy of more than 40 years. The introduction of new technologies, especially nanometer technologies with 90nm or smaller geometry, has allowed the semiconductor industry to keep pace with the increased performance-capacity demands from consumers. As a result, semiconductor test costs have been growing steadily and typically amount to 40% of today's overall product cost. 

This book is a comprehensive guide to new VLSI Testing and Design-for-Testability techniques that will allow students, researchers, DFT practitioners, and VLSI designers to master quickly System-on-Chip Test architectures, for test debug and diagnosis of digital, memory, and analog/mixed-signal designs.

KEY FEATURES
* Emphasizes VLSI Test principles and Design for Testability architectures, with numerous illustrations/examples.
* Most up-to-date coverage available, including Fault Tolerance, Low-Power Testing, Defect and Error Tolerance, Network-on-Chip (NOC) Testing, Software-Based Self-Testing, FPGA Testing, MEMS Testing, and System-In-Package (SIP) Testing, which are not yet available in any testing book.
* Covers the entire spectrum of VLSI testing and DFT architectures, from digital and analog, to memory circuits, and fault diagnosis and self-repair from digital to memory circuits.
* Discusses future nanotechnology test trends and challenges facing the nanometer design era; promising nanotechnology test techniques, including Quantum-Dots, Cellular Automata, Carbon-Nanotubes, and Hybrid Semiconductor/Nanowire/Molecular Computing.
* Practical problems at the end of each chapter for students.

System-on-Chip Test Architectures: Nanometer Design for Testability

This paper describes the new cell-aware test (CAT) approach, which enables a transistor-level and defect-based ATPG on full CMOS-based designs to significantly reduce the defect rate of manufactured ICs, including FinFET technologies. We present results from a defect-oriented CAT fault model generation for 1,940 standard library cells, as well as the application of CAT to several industrial designs. We present high volume production test results from a 32 nm notebook processor and from a 350 nm automotive design, including the achieved defect rate reduction in defective-parts-per-million. We also present CAT diagnosis and physical failure analysis results from one failing part and give an outlook for using the functionality for quickly ramping up the yield in advanced technology nodes.

Cell-Aware Test

High-quality at-speed scan testing, characterized by high small-delay-defect detecting capability, is indispensable to achieve high delay test quality for DSM circuits. However, such testing is susceptible to yield loss due to excessive power supply noise caused by high launch-induced switching activity. This paper addresses this serious problem with a novel and practical post-ATPG X-filling scheme, featuring (1) a test relaxation method, called path keeping X-identification, that finds don't-care bits from a fully-specified transition delay test set while preserving its delay test quality by keeping the longest paths originally sensitized for fault detection, and (2) an X-filling method, called justification-probability-based fill (JP-fill), that is both effective and scalable for reducing launch-induced switching activity. This scheme can be easily implemented into any ATPG flow to effectively reduce power supply noise, without any impact on delay test quality, test data volume, area overhead, and circuit timing.

https://hal-lirmm.ccsd.cnrs.fr/docs/00/19/56/82/PDF/ITC_LowPower.pdf

A novel scheme to reduce power supply noise for high-quality at-speed scan testing

Timing-related defects are becoming increasingly important in nanometer technology designs. Small delay variations induced by crosstalk, process variations, power-supply noise, as well as resistive opens and shorts can potentially cause timing failures in a design, thereby leading to quality and reliability concerns. We present a test-grading technique to leverage the method of output deviations for screening small-delay defects (SDDs). A new gate-delay defect probability measure is defined to model delay variations for nanometer technologies. The proposed technique intelligently selects the best set of patterns for SDD detection from an n-detect pattern set generated using timing-unaware automatic test-pattern generation (ATPG). It offers significantly lower computational complexity and it excites a larger number of long paths compared to previously proposed timing-aware ATPG methods. We show that, for the same pattern count, the selected patterns are more effective than timing-aware ATPG for detecting small delay defects caused by resistive shorts, resistive opens, and process variations.

/pdf/test-pattern-grading-and-pattern-selection-for-small-delay-1ganjexelv.pdf

Test-Pattern Grading and Pattern Selection for Small-Delay Defects

In this paper, a new ATPG methodology is proposed to improve the quality of test sets generated for detecting delay defects. This is achieved by integrating timing information, e.g. from Standard Delay Format (SDF) files, into the ATPG tool. The timing information is used to guide the test generator to detect faults through the longest paths in order to improve the ability to detect small delay detects. To avoid propagating faults through similar paths repeatedly, a weighted random method is proposed to improve the path coverage during test generation. During fault simulation, a new fault-dropping criterion, named Dropping based on Slack Margin (DSM), is proposed to facilitate the trade-off between the test set quality and the test pattern count. The quality of the generated test set is measured by two metrics: delay test coverage and SDQL. The experimental results show that significant test quality improvement is achieved when applying timing-aware ATPG with DSM to industrial designs.

Timing-Aware ATPG for High Quality At-speed Testing of Small Delay Defects

Capture-safety, defined as the avoidance of any timing error due to unduly high launch switching activity in capture mode during at-speed scan testing, is critical for avoiding test- induced yield loss. Although point techniques are available for reducing capture IR-drop, there is a lack of complete capture-safe test generation flows. The paper addresses this problem by proposing a novel and practical capture-safe test generation scheme, featuring (1) reliable capture-safety checking and (2) effective capture-safety improvement by combining X-bit identification & X-filling with low launch- switching-activity test generation. This scheme is compatible with existing ATPG flows, and achieves capture-safety with no changes in the circuit-under-test or the clocking scheme.

A Capture-Safe Test Generation Scheme for At-Speed Scan Testing

This paper presents a diagnostic test generation method for transition faults. As two consecutive vectors application mechanism, launch on capture test is considered. The proposed algorithm generates test vectors for given fault pairs using a stuck-at ATPG tool so that they are distinguished. If a given fault pair is indistinguishable, it is identified. Therefore the proposed algorithm provides a complete test generation regarding the distinguishability. The conditions for distinguishing a fault pair are carefully considered, and they are transformed into the conditions of the detection of a stuck-at fault, and some additional logic are inserted in a CUT for the test generation. Experimental results show that the proposed method can generate test vectors for distinguishing the fault pairs that are not distinguished by commercial tools, and also identify all the indistinguishable fault pairs.

http://lab.icc.skku.ac.kr/~vlsitest/2010_S/01.pdf

Diagnostic test generation for transition faults using a stuck-at ATPG tool

Test data modification based on test relaxation and X-filling is the preferable approach for reducing excessive IR-drop in at-speed scan testing to avoid test-induced yield loss. However, none of the existing test relaxation methods can control the distribution of identified donpsilat care bits (X-bits), thus adversely affecting the effectiveness of IR-drop reduction. In this paper, we propose a novel test relaxation method, called Distribution-Controlling X-Identification (DC-XID), which controls the distribution of X-bits identified from a set of fully-specified test vectors for the purpose of effectively reducing IR-drop. Experimental results on large industrial circuits demonstrate the effectiveness and practicality of the proposed method in reducing IR-drop, without any impact on fault coverage, test data volume, or test circuit size.

/pdf/effective-ir-drop-reduction-in-at-speed-scan-testing-using-zlttcsy2ab.pdf

Effective IR-drop reduction in at-speed scan testing using Distribution-Controlling X-Identification

We propose the fault model considering weak resistive opens inside the gate which might cause pattern-sequence-dependent and timing-dependent malfunction of the circuit. We assume the fixed observation interval for the signal transition, and derive the minimum resistance of intra-gate resistive opens to be detected as a fault by SPICE simulation. Based on the simulation results, we establish three fault models, that is, the one considering the location of the resistance, the one considering both the location and the resistance distribution, and the simplified one where str and stf faults considering the signal transition of the input ports are assumed. The coverage calculation for the primitive gates and small benchmark circuit reveals that the proposed models have more accuracy on the detection of weak open defects.

Takashi Aikyo

Papers

Timing-Aware ATPG for High Quality At-speed Testing of Small Delay Defects

A Capture-Safe Test Generation Scheme for At-Speed Scan Testing

Diagnostic test generation for transition faults using a stuck-at ATPG tool

Effective IR-drop reduction in at-speed scan testing using Distribution-Controlling X-Identification

Small Delay Fault Model for Intra-Gate Resistive Open Defects