Projection of circuit performance distributions by multivariate statistics

Production test data from process monitoring test structures were utilized in a circuit simulator that accounts for the correlations between circuit elements. This 'correlated' simulation is based on a principal component analysis technique that requires the means, the standard deviations, and the correlation coefficients of all circuit elements. A voltage reference subcircuit consisting of five n-p-n transistors and five based-diffused resistors was chosen for this simulation study. The statistical parameters of these circuit elements were approximated by those from the process monitor test structures and extracted from the test patterns of 1000 production wafers. The distributions of the reference voltage from this simulation were compared to a Monte Carlo simulation, and to the production data.>