High Temperature Solid Phase Crystallization of a-Si on Glass by Short Time Blue Laser Exposure for Display Backplane

Abstract

We report solid-phase crystallization (SPC) of amorphous silicon (a-Si) using blue laser annealing (BLA) and its application to thin film transistor (TFT). The a-Si film on glass was crystallized by exposure of blue laser for short duration of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$50~\mu \text{s}$ </tex-math></inline-formula> . The temperature of Si increases up to ~1100 °C and induces fast SPC. A 100 nm poly-Si on glass has full width at half maximum of Raman intensity 5.53 cm−1 and atomic force microscopy (AFM) root mean square surface roughness of 1.18 nm, indicating high quality poly-Si with smooth surface morphology without grain boundary. The coplanar SPC TFT using BLA exhibits the field effect mobility of ~27.0 cm2 / <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{V}\cdot \text{s}$ </tex-math></inline-formula> , on/off current ratio of >107 and excellent stability.