A First Approach to CVD Si_1–xGe_x Layer Growth by Means of Chemical Reaction Kinetics

Abstract

A reaction mechanism will be suggested for interpreting Si, -xGex CVD layer deposition from a silicon source and germane reaction gas mixtures in order to explain the observed silicon layer growth increase in consequence of the presence of germane. A successive substitution of the hydrogen atoms available in germane molecules by silyl groups forming a silicon containing intermediate of germane will be assumed. It will further be supposed that both the original silicon source and the germane intermediates will independently be decomposed by chemical reactions leading to Si, -xGex layer formation and that the reaction of the germane intermediates will be of 1st order. The reaction mechansim suggested will be discussed on the background of experimental data on Si,-.Ge, CVD layer deposition from dichlorosilane-germane-hydrogen reaction gas mixtures at temperatures in the range of 600 5 T("C) 5 900 as recently published by KAMINS and MEYER.

Kinetic Modeling of Low Temperature Epitaxy Growth of SiGe Using Disilane and Digermane

“…5 is simplified as: [6] m in this equation is called substitution coefficient. 24 "m" is related to be the number of silyl groups which have been substituted for hydrogen atoms in digermane molecules by a chemical gas reaction. Thus, an individual molecule of the hypothetical digermane intermediate transports not only a germanium atom from the gas to the surface but also "m" silicon atoms which will be incorporated in the epitaxial layer.…”