Kinetic Analysis of Electrode Heating Effects in a Torr-Regime Capacitively Coupled Plasma Reactor: 2-D Particle-in-Cell Simulation Study

Abstract

In the semiconductor industry, the electrode of a capacitively coupled plasma deposition reactor is often heated with the aim of process optimization. Based on chemical kinetics, a heated electrode can modulate the film properties or can enhance the growth rates of deposited thin films. Because the source gas undergoes rapid expansion in the hotter region near the electrode, the heated electrode is responsible for lowering the source density near the corresponding sheath. Thus, spatial variations in the kinetic parameters of the plasma such as the electron energy probability functions (EEPFs), ion energy distribution functions (IEDFs), and surface fluxes of ions can be controlled by changing the electrode temperature. Our simulation results indicated that a higher electrode temperature causes the direct ionization rate to increase, while the step-ionization rate decreases. In addition, the use of a heated electrode was observed to decrease the difference between the EEPF of the reactor center and that of the reactor edge. The improved consistency of the EEPF distribution implies that the homogeneity of the film quality between the center and edge of the wafer can be enhanced by improving the uniformity of the composition ratio of species.