화학공학소재연구정보센터
Journal of the Electrochemical Society, Vol.153, No.5, G363-G371, 2006
Low-temperature LPCVD of polycrystalline GexSi1-x films with high germanium content
A study of low-pressure chemical vapor deposition (LPCVD) of GexSi1-x (x < 0.65) films was carried out. The films were deposited on thermally oxidized silicon wafers at deposition temperatures of 430-480 degrees C. Pure GeH4 and SiH4 (or Si2H6) gas sources were used. It has been found that the reactive sticking probability ratio between GeH4 and SiH4 varies between 11 and 3.5, depending on both the deposition temperature and film composition. An increase of germanium content from 40 to 60 atom % caused a sharp increase of deposition rate. The polycrystalline layers mainly contained (110)- and (111)-oriented grains. The (111)-oriented grains were overgrown by the (110)-oriented grains at 430 degrees C after a film thickness of about 100 nm. Reducing the total pressure below 10 Pa led to a dominance of (111)-oriented grains. A relative GeH4 depletion in the downstream direction influenced both the composition and crystallinity of the layers, and the deposition rate. To minimize the depletion effect, Si2H6 has been used instead of SiH4. No improvement has been obtained but the depletion from Si2H6 occurred instead of the depletion from GeH4. A proper mixture of SiH4, Si2H6, and GeH4 can be suggested to compensate the depletion effects. (c) 2006 The Electrochemical Society.