Detection of CMOS defects under variable processing conditions

Transient signal analysis is a digital device testing method that is based on the analysis of voltage transients at multiple test points. In this paper, the power supply transient signals from simulation experiments on an 8-bit multiplier are analyzed at multiple test points in both the time and frequency domain. Linear regression analysis is used to separate and identify the signal variations introduced by defects and those introduced by process variation. Defects were introduced into the simulation model by adding material (shorts) or removing material (opens) from the layout. 246 circuit models were created and 1440 simulations performed on defect-free, bridging defective and open defective circuits in which process variation was modeled by varying circuit and transistor parameters within a range of ±25% of the nominal parameters. The results of the analysis show that it is possible to distinguish between defect-free and defective devices with injected process variation