Method for fabricating thin film transistors

Abstract

In a fabrication of a semiconductor device, an amorphous semiconductor film is first formed on a substrate having an insulating surface. Then, a minute amount of catalyst elements for accelerating crystallization of the amorphous semiconductor film is supplied to at least a portion of a surface of the amorphous semiconductor film. A heat treatment is further conducted so that the supplied catalyst elements are diffused into the amorphous semiconductor film. Thus, the catalyst elements are introduced uniformly into the amorphous semiconductor film in a very minute amount or at a low concentration, resulting in polycrystallization of at least a portion of the amorphous semiconductor film. Utilizing the thus obtained crystalline semiconductor film on the substrate surface as an active region, a semiconductor device such as a TFT is fabricated. The introduction of the catalyst elements are conducted by various methods such as: a formation of a film containing a minute amount of the catalyst elements; application of a solution containing the catalyst elements in several spin coating cycles; diffusion of the catalyst elements through a buffer layer; dipping into a solution in which the catalyst elements are dissolved or dispersed; or formation of a plating layer containing the catalyst elements.