Laser Dehydrogenation of PECVD Amorphous Silicon

Abstract

A low temperature process for laser dehydrogenation and crystallization of hydrogenated amorphous silicon has been studied. The key feature of this process is the removal of hydrogen from the amorphous silicon thin films while crystallizing the films at the same time. Studies of transient phenomena, hydrogen loss, and crystallinity, using transient reflectivity analyses, transmission electron microscopy and quadrupole mass spectrometry, find that hydrogen out-diffusion depends strongly on film structure and the melt duration controlled by the laser energy density. Utilizing this process, for which the maximum temperature is 350 °C, both high quality polycrystalline and amorphous silicon TFT's have been fabricated on the same Corning 7059 glass substrate.