Failing Frequency Signature Analysis

A failing frequency signature is a collection of the maximum operating frequencies of each pattern in a pattern set. Analyzing the failing frequency signature can successfully detect small-delay defects, because even a small-delay defect can cause an outlier to appear in a failing frequency signature. Moreover, the failing frequency signature will be consistent even in the presence of process variations. Failing frequency signature analysis can effectively detect very hard-to-find defects that occur in No-Trouble-Found (NTF) devices, without the necessity of thorough test patterns. The analysis can also be used for characterization tests. In this paper, experimental results using the failing frequency signature to detect small-delay defects are presented using test chips fabricated in a 0.18 mum technology.