Methodology of generating timing-slack-based cell-aware tests

Yu Teng Nien, Kai Chiang Wu, Dong Zhen Lee, Ying Yen Chen, Po Lin Chen, Mason Chern, Jih Nung Lee, Shu Yi Kao, Mango Chia Tso Chao

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


In order to reduce DPPM (defect parts per million), cell-aware (CA) methodology was proposed to cover various types of intra-cell defects. The resulting CA faults can be a 1-time-frame (1tf) or 2-time-frame (2tf) fault, and 2tf CA tests were experimentally verified to be capable of catching a significant number of defective parts not covered by other conventional tests. In this paper, we present a novel methodology for generating 2tf CA tests based on timing slack analysis. The proposed 2tf CA fault model, aware of timing slack and named TS, defines a fault (i) on a cell instance basis, and (ii) based on per-instance timing criticality (according to timing slack). More explicitly, for each cell instance with a specific defect injected, we check its output capacitive load and derive the corresponding extra delay. By comparing the extra delay against timing slack of the cell instance, a delay fault can be defined, and according to its severity, the fault can be further classified into small-delay fault or gross-delay fault. In contrast to prior 2tf CA methodology that is on a cell (rather than cell instance) basis and unaware of timing criticality/slack, our methodology can identify 'more realistic' faults which really need to be considered, and potentially the cost/effort for testing those 2tf CA faults can be reduced. Experimental results on a set of 28nm industrial designs demonstrate that, due to more realistic fault identification, the numbers of identified small-delay faults and corresponding test patterns to be applied can be reduced by 35.1% and 24.1% respectively, leading to 40.7% reduction in the runtime of ATPG.

Original languageEnglish
Title of host publication2019 IEEE International Test Conference, ITC 2019
PublisherInstitute of Electrical and Electronics Engineers Inc.
ISBN (Electronic)9781728148236
StatePublished - Nov 2019
Event2019 IEEE International Test Conference, ITC 2019 - Washington, United States
Duration: 9 Nov 201915 Nov 2019

Publication series

NameProceedings - International Test Conference
ISSN (Print)1089-3539


Conference2019 IEEE International Test Conference, ITC 2019
CountryUnited States

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