Measurement of Spatial Distributions of Gas Composition in Radio Frequency Discharge Plasmas Using a Quartz Sensor

Abstract

  We measured gas composition and its changes in the radio frequency glow discharge plasmas even near electrodes using a quartz sensor, whose output depends on molecular weight, viscosity and pressure of gas. By normalization on temperature, which mostly affects quartz sensor output particularly near the electrodes for the plasmas, the gas composition information can be obtained. Finally, this could make it possible to derive spatial distributions of the gas composition in the plasmas between the electrodes and chamber inner wall. The measurement was applied for low pressure hydrogen plasmas, which revealed that the gas composition change is attributed to the increase in carbon monoxide, methane and ethylene, probably produced at chamber inner wall. Sensitivity of the measurement was found to be better than 1 vol%.