In Situ Plasma Impedance Monitoring of the Oxide Layer PECVD Process

Abstract

The use of plasma in semiconductor fabrication processes has been continuously increasing because of the miniaturization of semiconductor device structure, and plasma enhanced chemical vapor deposition (PECVD) has become a major process in thin film deposition. As a consequence, plasma diagnosis has become crucial during the deposition process, but the lack of in situ plasma monitoring sensors requires further development of existing in situ sensors, such as the Langmuir probe and optical emission spectroscopy (OES), for in situ plasma process monitoring. In this study, electrically equivalent circuit models of the PECVD chamber functioned as a plasma impedance model with respect to the deposited thin film thickness while plasma impedance was measured using a radio frequency voltage–current (VI) probe. We observed a significant correlation between the deposited film thickness of the chamber wall and the measured impedance of the PECVD chamber cleaning application in the semiconductor industry.