Sublimation Process for Obtaining Silicon Films from Molybdenum and Tungsten Disilicide

Abstract.

Relevance. In existing methods of sublimational evaporation of silicon by resistive heating, careful control and adjustment of heating parameters is required. The sublimation temperature is limited in the range of ~1620÷1670 K. During resistive heating of silicon, it is necessary to carry out its additional heating with an electron beam gun to a temperature of the order 1100 K, at which silicon becomes conductive. In addition, the deposition rate of the films is limited and less than 1 µm/h. Accordingly, electron beam heating of silicon is widely used, but the disadvantage of such a source is the presence in the stream of silicon atoms of the droplet fraction, due to rapid local overheating. This paper proposes to conduct a study of the sublimational evaporation of silicon from refractory metals.

Purpose. The purpose of the study is to extend the operating temperature range of silicon evaporation for more convenient control of regulation and increase the rate of silicon deposition by increasing the pressure of silicon vapour.

Methods. For sublimational deposition of silicon-based structures, a gas-phase method was used, which developed and obtained a source of MoSi2 and WSi2 atoms.

Results. This paper proposes to conduct a study of the sublimational evaporation of silicon from refractory metals. Sublimation sources, which are compounds of MoSi2, WSi2, are obtained by the gas-phase method from the hydrogen reduction reaction SiCl4+2H2 →Si+4HCl. It is determined that the evaporation rate of silicon from refractory metals increases due to an increase in the vapour pressure of silicon, and the evaporation temperature range expands for more convenient control of the film deposition process. It is shown that the evaporation rate Si from a sublimation source MoSi2 and WSi2 is greater than the evaporation rate of silicon (resistive evaporation, electron beam method, evaporation from an effusion cell) at its sublimation temperature. The temperature range of sublimation deposition has been extended from 1780 to 2100⥂K, which greatly improves the control of sublimation temperature regulation.

Conclusions. Sublimation sources 1780 and WSi2 extend the temperature range of silicon evaporation from 1780 to 2100⥂K for more convenient control regulation and increase the rate of silicon deposition by increasing the pressure of silicon vapour

Keywords: source of silicon atoms, refractory silicides, thin-film solar cells, silicon structures

https://doi.org/10.24144/2415-8038.2021.49.48-53