Experimental and numerical study of Si annealed by laser sources of the visible spectrum (red and blue wavelength)

Abstract

Laser annealing (LA) is an increasingly important process in the semiconductor manufacturing industry. So far, lasers of nonvisible spectrum have been mostly used for semiconductor applications. The study using a visible wavelength laser is not nearly found though it could be a potential tool to expand applications of the LA. In this study, the silicon (Si) deposited on oxide was annealed using laser sources of visible spectrum. LA of Si was performed using a single laser source of either red or blue wavelengths or a dual-laser source using both wavelengths. The surface morphology and microstructure of the annealed Si were analyzed. A numerical simulation was also conducted to predict the temperature and melt pool characteristics of Si during the annealing process. Surface roughness increased with increasing heat input (or power density) of the laser beam, owing to the considerable melting of Si. The dual laser using a relatively high power density produced Si with high polycrystallinity and large grains. However, the Si lattice constant difference induced by different annealing conditions was negligible. Simulation results showed that temperature, melt pool length, and duration increased with the power density of the dual-laser beam. This contributed to the growth of large Si grains.