The Selective Deposition of a Silicon Film on Hydrogenated Amorphous Silicon by Mercury Sensitized Photochemical Vapor Deposition

Abstract

The authors have developed a low-temperature process for the first time for the selective deposition of a silicon film on hydrogenated amorphous silicon (a-Si:H) and on silicon nitride (SiN x ) surfaces by mercury sensitized photochemical vapor deposition (Photo-CVD). The selective deposition of Si films was able to be achieved by hydrogen radical cleaning for 1 minute prior to the deposition. There were two different incubation periods for the a-Si:H and SiN x surfaces. Selective deposition was obtained by using this difference in the incubation periods between the deposition on an a-Si:H surface and on a SiN x surface. The field effect mobility and the off leakage current for thin film transistor (TFT) of the fabrication by using this selective deposition technique were of the 0.6 cm2 V-1 s-1 and 10-11 A order, respectively. It has been confirmed that photo-CVD is a promising method for the selective deposition process at a low temperature using a large-area glass substrate.