Real-Time Plasma Uniformity Monitoring via Selective Plasma Light Intensity Measurement Using Transparent-LCD-Module-Adapted Optical Emission Spectroscopy

A real-time selective plasma light intensity measurement technique involving optical emission spectroscopy (OES) is proposed for process uniformity monitoring and detection in various plasma regions during semiconductor processing. Among plasma diagnostic techniques, OES is a noncontact plasma measurement technique for process end point and plasma abnormality detection that does not cause any process damage. Therefore, it is mostly used in all plasma-based tools. However, conventional OES systems are incapable of real-time plasma uniformity detection at specific OES sampling times, and therefore, there is a need for improving them. In this study, we show that selective plasma light intensity, including those on the left and right sides of a process chamber, can be measured with transparent-LCD-module-adapted conventional OES for determining process uniformity. The proposed technique can be used to measure the selective plasma light intensity in specific regions of the process chamber, such as the center and edge regions of a wafer, and to thereby analyze the plasma process uniformity.