Influences of deposition and crystallization kinetics on the properties of silicon films deposited by low-pressure chemical vapour deposition from silane and disilane

Abstract

The paper deals with the properties of silicon films obtained by low-pressure chemical vapour deposition (LPCVD). Two gaseous sources characterized by different deposition temperatures, i.e. disilane Si 2H 6 (420–520 °C) and silane SiH 4 (520–750 °C), was studied in order to understand the influences of deposition and crystallization kinetics on silicon film properties. Thus, the deposition of amorphous, semi-crystallized and polycrystalline silicon films was related to “volume random” and “surface columnar” crystallization phenomena, highlighting a linear relationship between the refractive index and the polysilicon volume fraction and, showing complex residual stress dependency with process conditions. Finally, by introducing the ratio V d/V c between the deposition and crystallization rates as a major parameter, different deposition behaviours and related semi-empirical relationships were defined in order to characterize fully the various properties of LPCVD silicon films (microstructure, polysilicon volume fraction, refractive index and residual stress) according to the chosen gaseous source, silane or disilane.