Control of gas-phase nucleation and flow visualization in a special cold wall CVD reactor

CNRS-IMP, University of Perpignan, 52 avenue de Villeneuve, 66860 Perpignan Cedex, France

Corresponding author: wang@univ-perp.fr

Received: 18 June 1997
Revised: 3 March 1998
Accepted: 31 March 1998
Published online: 15 July 1998

Abstract

The deposition of the ternary compound Ti-N-Si using the cold-wall CVD technique from TiCl₄-NH₃-SiH₂Cl₂ presents difficulties because of undesired powder formation in the gas-phase. For a better understanding and control of the mechanism, both simulation and experiments have been carried out to determine favorable conditions to minimize the undesired adducts. First, an original technique has been developed for the reactive injection with a double-passage nozzle specially designed. Then powders have been deliberately grown at different conditions, with their chemical compositions analyzed using X-ray diffraction spectra. Further, the flow has been modeled and compared with the results provided by means of laser sheet visualization. It is shown that the powders can be avoided with some special reactive injection schemes and by controlling the nozzle exit-substrate distance. Some useful information is also delivered on controlling the color and the composition of powders during their synthesis.