Hot-wire CVD growth simulation for thickness uniformity

Obtaining thickness uniformity over a large substrate area seems to be a bo ttleneck 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 re spect, we have simulated the hot-wire CVD growth process and proposed a pro per filament geometry for maximum thickness uniformity. The hot filament wa s assumed as a one-dimensional assembly of point sources. Five types of com monly used filament geometries were considered for their performance to ide ntify the best filament geometry for maximum thickness uniformity. Here, th e chamber pressure was assumed to be low enough so that the Knudsen number K-n > 1. Based on out results, we propose a parallel filament geometry for maximum thickness uniformity over large substrate areas. By applying the mo del further to the parallel filament geometry, the relations between substr ate-filament distance and minimum filament length, as well as the number of parallel filaments and the separation between them, which are necessary fo r the required thickness uniformity over the given substrate area, were det ermined. The validity of the model was checked using the 'Matched-Pair t-te st'. The effect of chamber pressure on thickness uniformity and growth rate , when it is sufficiently high to make the Knudsen number K-n < 1, was also simulated. The thickness uniformity was observed to increase with an incre ase in chamber pressure. (C) 2001 Elsevier Science B.V. All rights reserved .