Emission spectra study of plasma enhanced chemical vapor deposition of intrinsic, n~+, and p~+ amorphous silicon thin films

摘要

The PECVD intrinsic, n~+, and p~+ a-Si:H thin film deposition processes have been studied by the optical emission spectroscope to monitor the plasma phase chemistry. Process parameters, such as the plasma power, pressure, and gas flow rate, were correlated to SiH~*, H_α~*, and H_β~* optical intensities. For all films, the deposition rate increases with the increase of the SiH~* intensity. For the doped films, the H_α~*/SiH~* ratio is a critical factor affecting the resistivity. The existence of PH_3 or B_2H_6 in the feed stream enhances the deposition rate. Changes of the free radicals intensities can be used to explain variation of film characteristics under different deposition conditions.