Performance analysis of adaptive scan compression methodology and calculations of compression ratio

Abstract

During fabrication of chip, manufacturing defects like open or shot may occur which cause malfunctioning of the chip. Design-for-Test (DFT) is extensively used to identify such defects. On tester, test data is applied to the chip to identify the defects. For larger chip, the amount of test data volume and test application time is higher on tester. Adaptive scan compression method is used to reduce test application time and test data volume. This paper gives an overview of the technique and discusses the factors that influence test parameters: compression ratio, test data volume reduction (TDVR) and test application time reduction (TATR). We also present the relationship of TATR, TDVR and Total no of internal scan chain. Results of experiments conducted to validate the relationship are also reported. © 2011 Springer-Verlag.