Compact test sets for high defect coverage

Abstract

It was recently observed that, in order to improve the defect coverage of a test set, test generation based on fault models such as the single-line stuck-at model may need to be augmented so as to derive test sets that detect each modeled fault more than once. In this work, we report on test pattern generators for combinational circuits that generate test sets to detect each single line stuck-at fault a given number of times. Additionally, we study the effects of test set compaction on the defect coverage of such test sets. For the purpose of experimentation, defect coverage is measured by the coverage of surrogate faults, using a framework proposed earlier. Within this framework, we show that the defect coverage does not have to be sacrificed by test compaction if the test set is computed using appropriate test generation objectives. Moreover, two test sets generated using the same test generation objectives, except that compaction heuristics were used during the generation of one but not the other, typically have similar defect coverages, even if the compacted test set is significantly smaller than the noncompacted one. Test generation procedures and experimental results to support these claims are presented.

SAT-based analysis of sensitisable paths

“…Note that the number of generated test pairs is intended to be large (typically one test pair for each considered path, even though some pairs may be valid for multiple paths) to provide a variety of tests from which the most effective ones can be selected by adaptive test. In some sense this is similar to n-detection [11], [12], [13], but the resulting test pairs are much more targeted towards defect detection and also more diversified, as they are guaranteed to sensitise different paths.…”

An enhanced fault model for high defect coverage

“…The nonfeedback AND-bridging fault (denoted BF) is taken as the surrogate fault of physical defects [1,2] and Table 3. SGLFH1s detected by a test set for SSAF detection the fault coverage of the test set generated for SGLFH1s is considered.…”

“…A multiple detection test pattern set for SSAFs is a test pattern set in which each SSAF is detected more than some specified number of times. Next, we show, by using bridging faults between signal lines as the actually occurring surrogate faults [1,2], that the test pattern set for the SGLFH1 model is smaller than the multiple detection test pattern set for the SSAF model and achieves a high level of defect coverage. The ATPG for the SGLFH1 model can be easily made by partial modification of the ATPGs of a large number of SSAFs.…”

“…Next we show that the multiple detection test pattern set for single stuck-at faults that is conventionally used to enhance defect coverage does not detect SGLFH1 faults satisfactorily. In addition, the effectiveness of the proposed model is shown by comparing the fault detection ratio of the SGLFH1 test pattern set for physical surrogate faults [1,2] with the corresponding fault detection ratio of the multiple detection test pattern set for single stuck-at faults. © 2001 Scripta Technica, Syst Comp Jpn, 32(6): 3644, 2001 …”

Towards Variation-Aware Test Methods

“…On the other hand, they may be inefficient, that is, require an unreasonable amount of resources. For example, n-detection (testing the same fault by n different test patterns) [34] tends to increase the test quality, yet it also leads to a significant increase of test data volume and test application time.…”