Harmonic Analysis of Wafer Fabrication Data in the Frequency Domain : Topic: Advanced Process Control

Wafer fabrication process data were analyzed in this paper using both linear and nonlinear bispectral analyses to examine the behavior of harmonics in the frequency domain. We used the spectral analyses to characterize and quantify the dynamic behavior of signal harmonics in the frequency domain. We focused on the measurements collected from three particular processing parameters during wafer processing. The data were divided into consecutive short segments to provide time-stamped behavior of the harmonic distributions. We also applied the nonlinear bispectral analysis to show that quadratic phase coupling interactions between the fundamental frequency and its harmonics exist, which contributes largely to the generation of multiple harmonics. Our results find that process measurements of the examined parameters exhibit a progressive change in time where the harmonic frequencies gradually reduced.