The Discharge Characteristics of Capacitively Coupled Ar Plasma as the Change of Pressure

The discharge characteristics of coupled capacitively argon plasmas with change of pressure are studied. The mean electron temperature and electron density are calculated via Ar spectral lines at different pressures (10–80 mTorr) and at four frequencies (13.56, 40.68, 94.92, and 100 MHz). From 10–30 mTorr, the mean electron temperature and the electron density both decrease with the increase of pressure at certain frequency. From 30–80 mTorr, the mean electron temperature similarly first increase then decrease with pressure at 94.92 and 100 MHz, and decrease at 40.68 MHz and increase at 13.56 MHz with pressure. The largest mean electron temperature is found at 40.68 MHz. From 40–80 mTorr, the electron density both increase at 94.92 and 100 MHz. The electron density change little at 40.68 and 13.56 MHz with pressure increase. Particle-in-cell/Monte Carlo collisions (PIC/MCC) method developed within the Vsim 8.0 simulation package is used to simulate the electron density, the potential distribution and the electron energy probability function (EEPF) under the experimental condition. Sheath width decrease with the pressure increase. The EEPF of 40.68 MHz is bi-Maxwellian and 100 MHz are nearly Maxwellian with a large population of low-energy electrons with the increase of pressure.