Double Laser Crystallization (DLC) of 50 Nanometer and 20 Nanometer Amorphous Silicon Film for Thin Film Transistors (TFTS) Application

Abstract

Ultra-large grain poly-crystalline silicon has been formed in 20 nm and 50 nm amorphous silicon films by the double laser crystallization (DLC) method. Surface reflection properties of such thin films upon laser irradiation were calculated. In-situ images were captured to monitor the transient melting and solidification process of 50 nm silicon film in order to understand the crystallization induced by steep laser intensity gradients. SEM (scanning electron microscope) images of crystallized 50 nm film after Secco etch revealed grain size up to 10 m while plane-view TEM (transmission electron microscope) images of 50 nm film also showed perfect crystalline structure inside the grains. AFM (atomic force microscope) images were also taken to show the topology of the grain structure and RMS of 20 nm film.