Real-time observation of the capacitance variation in a surface dielectric layer in radio frequency discharge

Abstract

The capacitance of an Al2O3 layer coated on a probe was measured in real-time in plasma using the harmonic method. The measured capacitance was influenced by the applied power and the exposure time to the plasma. Upon varying the power, the capacitance quickly changed and then slowly saturated. The change in the capacitance was partly understood to be due the temperature dependence of the dielectric constant. However, the rate of the capacitance change as a function of temperature was higher than that typically observed, and the quick response to varying power was too fast to be explained by the temperature variation. These results showed that other effects besides temperature should be considered to explain this phenomenon.