Effects of the Electrode Temperature on Spatial Distributions of Plasma Parameters in Intermediate Pressure Capacitively Coupled Plasmas

Abstract

Non-isothermal wall conditions are often adopted to optimize process results for plasma enhanced chemical vapor deposition (PECVD). Due to the importance of multicomponent transport, Kim and Lee reported that gas velocity and temperature distributions affect the spatial distributions of neutral radicals and even electrons and ions [1]. Since the high temperature of the electrode causes depletion of background gas due to the ideal gas law, ion energy and angle distributions (IEADs) are changed due to the reduced collisions of ions with neutrals. In a recent semiconductor industry, it is required to achieve the extreme uniformity of the spatial distributions of not only the ion energy but also the angle distributions. Thus, we investigated the effects of electrode temperature on plasma parameters, especially IEAD, in intermediate pressure capacitively coupled plasmas (CCPs) using two-dimensional particle-in-cell/Monte Carlo collision method. It was found that plasma density decreased, while sheath size increased with the higher temperature of the electrode. It was also found that ion energy increased, and angle became narrower due to fewer collision. The spatial variation of IEADs was also affected by the change of the electrode temperature. As a case study for PECVD, SiH4/He capacitively coupled plasma was selected to deposit a hydrogenated amorphous silicon film. In this deposition simulation, a fluid model was used. It was found that a sufficient increase of the electrode temperature was best for obtaining a uniform deposition rate profile in the test bed.