The Kinetics of the Low‐Pressure Chemical Vapor Deposition of Polycrystalline Silicon from Silane

Abstract

The kinetics of the deposition of polycrystalline silicon from silane were studied at 25–125 Pa and 863–963 K using a continuous flow perfectly mixed reactor equipped with a microbalance and a quadrupole mass spectrometer for in situ deposition rate measurements and on‐line gas‐phase analysis. It was possible to obtain rate coefficients that are intrinsic, i.e., only determined by chemical phenomena. A four‐step elementary gas‐phase reaction network coupled to a ten‐step elementary surface network was able to describe the experimental data. Pressure falloff behavior of gas‐phase reactions was taken into account using the Rice‐Rarnsberger‐Kassel‐Marcus theory. In the surface reaction mechanism, adsorption of silane, hydrogen, and highly reactive gas‐phase intermediates and first‐order desorption of hydrogen are the only kinetically significant steps. Silylene and disilane are the most abundant gas‐phase intermediates, causing typically one fifth of the overall silicon growth.