Double Laser Crystallization (DLC) of Pre-Patterned Amorphous Silicon Film and Amorphous Silicon Film With a Patterned Assisting SiO2 Layer

Abstract

In this study, pre-patterned amorphous silicon films are crystallized by the double laser crystallization (DLC) technique. Temperature distribution upon laser irradiation is modified by patterning the a-Si film, thus controlling the crystal growth. Patterns with a flattened concave feature is found to be favorable for large crystal growth with high localization, yielding grains with the size of 1.5 μm × 4 μm. As an alternate method (to pre-patterning the amorphous silicon film) for obtaining large crystal growth, double laser crystallization of amorphous silicon film with patterned SiO2 cap layer is proposed. The SiO2 layer assists the lateral growth of the crystals by acting as a thermal reservoir and slowing down the cooling rate, and additionally helps reduce the roughness of the polycrystalline surface to about 3nm (R.M.S.). With this alternate method, the grain width is increased from 0.5 μm to 1.5μm.