On Generation of 1-Detect TDF Pattern Set with Significantly Increased SDD Coverage

Small-delay defect (SDD) testing is expected to become mandatory for high quality products as technology scales and design frequency increases. Traditional timing-unaware transition-delay fault (TDF) ATPGs are not effective for detecting SDDs. Commercial timing-aware ATPGs suffer from huge pattern count and high CPU runtime. A small pattern set with high SDD coverage is desired by industry. In this paper, a comprehensive pattern grading and selection procedure is proposed to meet the requirement. During pattern evaluation, a new SDD-TDF aware metric is proposed to facilitate the trade-off between SDD detection, gross TDF detection and pattern count. By adjusting the relative weight for SDDs and gross TDFs, the final pattern set with high SDD detection efficiency and sufficient TDF coverage could be framed in 1-detect volume. The quality of the final pattern set is measured considering both the number of detected SDDs and the detectable SDD size. Experimental results on both IWLS and ISCAS89 benchmarks demonstrate the efficiency of the proposed SDD screening scheme.