Hot-wire CVD growth simulation for thickness uniformity

Abstract

Obtaining thickness uniformity over a large substrate area seems to be a bottleneck as far as the industrial applications of the hot-wire CVD (Cat-CVD) process is concerned. In order to address the different issues in this respect, we have simulated the hot-wire CVD growth process and proposed a proper filament geometry for maximum thickness uniformity. The hot filament was assumed as a one-dimensional assembly of point sources. Five types of commonly used filament geometries were considered for their performance to identify the best filament geometry for maximum thickness uniformity. Here, the chamber pressure was assumed to be low enough so that the Knudsen number Kn>1. Based on our results, we propose a parallel filament geometry for maximum thickness uniformity over large substrate areas. By applying the model further to the parallel filament geometry, the relations between substrate–filament distance and minimum filament length, as well as the number of parallel filaments and the separation between them, which are necessary for the required thickness uniformity over the given substrate area, were determined. The validity of the model was checked using the ‘Matched-Pair t-test’. The effect of chamber pressure on thickness uniformity and growth rate, when it is sufficiently high to make the Knudsen number Kn<1, was also simulated. The thickness uniformity was observed to increase with an increase in chamber pressure.