Detection of defects using fault model oriented test sequences

This paper analyzes the possibilities and limitations of defect detection u sing fault model oriented test sequences. The analysis is conducted through the example of a short defect considering the static voltage test techniqu e. Firstly, the problem of defect excitation and effect propagation is stud ied. It is shown that the effect can be either a defective effect or a defe ct-free effect depending on the value of unpredictable parameters. The conc ept of 'Analog Detectability Interval' (ADI) is used to represent the range of the unpredictable parameters creating a defective effect. It is demonst rated that the ADIs are pattern dependent. New concepts ('Global ADI', 'Cov ered ADI') are then proposed to optimize the defect detection taking into a ccount the unpredictable parameters. Finally, the ability of a fault orient ed test sequence to detect defect is discussed. In particular, it is shown that the test sequence generated to target the stuck-at faults can reasonab ly guarantee short defect detection till a limit given by the Analog Detect ability Intervals.