Wall-Less Like Reactor : Simulation and Experimental Results

The formation of thin films in the conventional thermally activated chemical vapour deposition process is based on heterogeneous reactions involved in surface nucleation and growth. Nevertheless, the influence of homogeneous reactions has often been underestimated, and the intermediate species that are formed from homogeneous reactions may have a great influence on the deposition mechanism. In order to study the formation of these species, a specific reactor has been designed, in which the effects of gas-phase and surface reactions can be separated and so clearly identified. In order to limit the influence of surface phenomena, a so called wall-less reactor has been developed. In such a reactor, the reactive gas mixture is heated by mixing with a hot inert gas. Two basic configurations have preliminary been optimized by simulation modelling using the Si-H chemical system. A reactor has been designed according to these calculations. Comparison of the calculated flow pattern with that visualized by the laser sheet method shows an excellent agreement, that partially validates our model. The reactor is coupled with Raman spectroscopy, that allows both the determination of the local temperature of the gas phase and the detection of gaseous species.