Analysis of Gas Detection Sensitivity of a Self Plasma-Optical Emission Spectrometer Using an N₂ and Ar Gas-Mixing Evaluation System

A self plasma-optical emission spectrometer (SP-OES) is a sensor that analyzes the residual gases in an exhaust line by detecting the intrinsic wavelength of the species excited by the self-plasma module.SP-OESs are used in semiconductor processes, such as cleaning, etching, and deposition, for leak detection and process monitoring.In recent years, with the shrinking scale of semiconductor processes, detection of small variations in gas compositions has become crucial.Therefore, the sensitivity of SP-OESs must be analyzed and optimized for advanced process monitoring in the future.However, the SP-OES detection sensitivity has been rarely quantitatively evaluated and optimized.In this study, various parameters that affect the detection sensitivity of SP-OESs were analyzed and optimized using a gas-mixing system to determine the dependence of the sensitivity on a predetermined gas-mixing ratio.The limit of detection was obtained to evaluate the sensitivity of SP-OESs.Parameters such as the integration time for photon collection, pressure under the self-plasma module, and selected wavelength were analyzed to improve the sensitivity of SP-OESs.