Determination of the power and current densities in argon and oxygen plasmas by i n s i t u temperature measurements

Abstract

I n situ temperature measurements of silicon wafers in argon and oxygen plasmas are presented. The processes which determine the heat flow from and to the wafer have been established. It is found that conduction of heat to the electrode does not contribute to the heat loss of the wafer. Radiation of heat and conduction of heat by the gas are the main loss processes. The heat flux qp from the plasma to the wafer is independent of time and temperature. This is attributed to the flux of high-energy ions to the wafer. By measuring the plasma potential, the energy of the ions is estimated. The ion current density is calculated from qp and the energy of the ions. The value which is obtained is compared to those obtained with other methods. It is concluded that the power density on the electrode can differ by almost an order of magnitude from an estimation using the dissipated rf power and the electrode area.