In situ Fourier transform infrared spectroscopy and stochastic modeling of surface chemistry of amorphous silicon growth

Abstract

We present a combined experimental and theoretical study of the formation of silicon hydride surface species during the F2 laser (157 nm) chemical vapor deposition of amorphous hydrogenated silicon (a-Si:H). A one-dimensional stochastic model has been applied to simulate the growing surface. The predictions of the model were compared to the results of Fourier transform infrared transmission spectroscopy providing submonolayer resolution. We present a qualitative analysis of the bonding configuration in the initial stage of film growth on H-terminated Si(111). The high sensitivity and resolution of the spectroscopic method allowed us to distinguish between four surface species by a deconvolution of the observed feature around 2100 cm-1 during the deposition process. The theoretical results for the evolution of the different surface species and bulk hydrogen are in close agreement with these spectra. Consistence between mass spectrometric data and simulation was also achieved for the growth rate and bulk hydrogen content as a function of disilane partial pressure and laser intensity. The good agreement between experiment and simulation obtained in this work indicates that it is possible to describe the main features of the complex chemical system of the growing film with a model based on a few dominant surface reactions. © 1998 American Institute of Physics.