Thick PECVD Germanium films for MEMS Application

Abstract

Plasma enhanced chemical vapour deposition (PECVD) of thick germanium (Ge) films (~1 m) on silicon di-oxide (SiO2) at low temperatures is described. A diborane pre-treatment on SiO2 films is done to seed the Ge growth, followed by the deposition of thick Ge films using germane (GeH4) and argon (Ar). Further, the effect of hydrogen (H2) dilution on the deposition rate is also investigated. The film thickness and morphology is characterized using SEM. Use of high RF power and substrate temperature show increased deposition rate. EDS analysis indicates that these films contain 97–98 atomic percentage of Ge. A recipe for anisotropic dry etching of the deposited Ge films with 10 nm/min etch rate is also suggested.