Low-Temperature Chemical-Vapor Deposition of Amorphous Semiconductors and Insulators

Abstract

We have developed a low-temperature (plasma-free) thermal-CVD method for the purpose of eliminating the plasma-CVD method on the amorphous-silicon thin-film transistor (a-Si TFT) process. The motivation comes from the fact that, in the plasma-CVD method, there arc many shortcomings originating from inherent properties of plasma, and that only the CVD method has potentially no drawbacks among various alternative methods. High deposition temperature, the most serious technological barrier in the present a-Si and silicon- nitridc (SiN) CVD methods, has been overcome by the use of high silicon-hydridcs and high nitrogen-hydrides for source gases. Electronic properties of the CVD-produced a-Si film arc improved by post-hydrogenation. Excimer-laser annealing is the next generation technology for improving dramatically the electronic properties of the CVD-produced Si and SiN films. This paper reviews these novel technologies developed in our group aiming at the TFT process, and also the CVD-produced TFT characteristics.