Spectroscopic analysis in laser annealing LT poly-Si TFTs

Abstract

We investigated the optic characteristics of XeCl excimer laser annealed (ELA) amorphous silicon in this study. The 50 nm PECVD a-Si film was deposited on PECVD oxide with a thickness of 300 nm. Then the samples were heated to reduce its hydrogen content and crystallized with a wide range of 308 nm XeCl excimer laser energy densities. It was found that the structure and optic characteristics of Poly-Si film is a function of the extent of crystalline of Poly-Si film. For example, in the transmittance spectroscopic range of 420-610 nm, the transmittance is dependent on the extent of crystalline of Poly-Si film. Therefore we can use these optic characteristics of Poly-Si film to monitor the extent of crystallization of Poly-Si films. Correlations between optic characteristics of laser crystallized Poly-Si, ELA energy density and surface roughness were discussed to monitor the Poly-Si film quality.