Laser-Induced Local Decomposition of Adsorbed Tungsten Fluorine Molecules for Metal Deposition on Silicon

Abstract

ABSTRACTDecomposition of tungsten hexafluoride on silicon substrates under CW argon laser irradiation in the visible domain has been extensively studied in presence of various buffer or reactive gases. The decomposition rate is found to be limited either by a mass transport phenomena or by a thermally activated process. It has been found that no photolytic decomposition can be invoked as the limiting step in the decomposition rate. Depending on the partial pressure of added hydrogen, irradiation results in a local deposition of tungsten, having good electrical properties. In the high pressure domain, deposition kinetics are consistent with mechanisms invoked in conventional chemical vapor deposition reactors. A different mechanism appearing in a lower hydrogen pressure domain will be tentatively interpreted in correlation with the laser-induced temperature.