Rapid optical measurement of surface roughness of polycrystalline thin films

Abstract

Excimer laser crystallization is the most commonly employed technology for fabricating low temperature polycrystalline silicon (LTPS) thin films. Investigations on the surface roughness of polycrystalline silicon (poly-Si) thin films become an important issue because the surface roughness of poly-Si film is widely believed to be related to its electrical characteristics. A simple optical measurement system for rapid surface roughness measurement of poly-Si thin films is developed in this study. It is found that y=−1.4533 x+0.6932 is a trend equation for predicting the surface roughness of poly-Si thin films. The x and y represent the peak power density and the surface roughness of poly-Si thin films, respectively. The incident angle of 60° is a good candidate for measuring the surface roughness of poly-Si thin films. The surface roughness of poly-Si thin films ( y) can be directly determined from the peak power density ( x). The maximum measurement error rate of the optical measurement system developed is less than 2.1%. The savings in measurement time of the surface roughness of poly-Si thin films is up to 83%.