Measurement of SiH2 Densities in an RF-Discharge Silane Plasma Used in the Chemical Vapor Deposition of Hydrogenated Amorphous Silicon Film

Abstract

Silylene (SiH2) radicals have been detected by intracavity laser absorption spectroscopy in a parallel plate RF-discharge system used in the chemical vapor deposition of hydrogenated amorphous silicon. By the use of two different calibration methods, an absolute density ranging from 2×108 to 6×109 cm-3 has been obtained as a function of the input RF power and of the partial pressure of SiH4. The flux of SiH2 onto the substrate electrode estimated from the gradient of the spatial distribution is less than 1013 cm-2 s-1. This suggests that its direct contribution to the film deposition is small, although it plays an important role in gas phase reactions.