Growth and Etching of Germanium Films by Chemical Vapor Deposition in a GeCl4 ‐ H 2 Gas System

Abstract

The etching and growth of germanium films are investigated using a gas system in the temperature range of 490°–565°C. At relatively low partial pressures less than , epitaxial growth of Ge is observed on Ge (100) surfaces, whereas at partial pressures higher than , etching of the Ge film is found to occur. In the experiments utilizing patterned substrates, where the surface consists of defined areas of Ge and , Ge is found to deposit selectively only on the exposed Ge regions. The growth reactions of Ge epitaxial films proceed through the Langmuir‐Hinshelwood mechanism: the surface reaction takes place between two hydrogen atoms dissociatively adsorbed and a surface‐adsorbed molecule. molecules adsorbed on the surface are formed directly from molecules, not through gas‐phase reduction by hydrogen. On the other hand, the etching reaction of Ge films is proved to be a reverse disproportionation reaction: . Based on the analyses of growth and etching reactions, the equation of the Ge epitaxial film's growth rate is derived as a function of partial pressure, hydrogen partial pressure, and growth temperature.