Crystallization of Double-Layered Silicon Thin Films by Solid Green Laser Annealing and Its Application to Low Temperature poly-Si Thin Film Transistors

Abstract

In this study, we propose a novel laser-crystallization technique by employing a double-layered Si thin films substrate for solid green laser anneal (GLA) crystallization, named GLADLAX (Green Laser anneal Double Layer X'tallization). Simultaneous crystallization of both the upper and the lower a- Si films of the substrate in a single laser scan was successfully achieved, with the upper a-Si becoming poly-Si with fine crystallinity, and the lower one, μc-Si. In addition, it was found that approximately 30% of the laser energy was reduced to obtain nearly the same grain size of the upper poly-Si formed through the GLADLAX technique, compared with that of the conventional GLA crystallized single layer poly-Si. Furthermore, we fabricated thin-film transistors using the upper Si film of GLADLAX poly-Si as their active channels, and found they had excellent switching performance, with their mobility exceeding 350cm2/Vs.