The Effectiveness of IDDQ, Functional and Scan Tests: How Many Fault Coverages Do We Need?

Abstract

This paper addresses the issue of achieving high quality by quantifying fault coverages for a number of different types of faults. Firstly it is shown how coverage requirements become more stringent with increasing chip area. Data is then presented from a production part tested with IDDO, scan, timing and fuxtional tests. Three different coverage metrics are considered for the IDDQ tests and the relative effectiveness of the different components of the full test suite are analyzed. It is demonstrated that no component can be removed without suffering a reduction in quality.