Estimation of Process Time Delay between Chamber Measurements and Optical Emission Spectroscopy : APC: Advanced Process Control

Time delay between chamber measurements and optical emission spectroscopy (OES) data were estimated using the cross-spectral analysis in this paper. The time delay between control and key variables provides useful feedback in etching control processes. We found in our study that ramping the chamber pressure during the etch process leads to an increasing time delay at the first harmonic between the chamber pressure and bias voltage measurements and a decreasing time delay between the chamber pressure and a selected OES wave band.