Method of controlling film uniformity and composition of a PECVD-deposited A-SiN_x : H gate dielectric film deposited over a large substrate surface

摘要

We have discovered that adding H₂ to a precursor gas composition including SiH₄, NH₃, and N₂ is effective at improving the wet etch rate and the wet etch rate uniformity across the substrate surface of a-SiN_x:H films which are deposited on a substrate by PECVD. Wet etch rate is an indication of film density. Typically, the lower the wet etch rate, the denser the film. The addition of H₂ to the SiH₄/NH₃/N₂ precursor gas composition did not significantly increase the variation in deposited film thickness across the surface of the substrate. The uniformity of the film across the substrate enables the production of flat panel displays having surface areas of 25,000 cm² and larger.