Growth Mechanism of Laser Annealing of Nickel-Induced Lateral Crystallized Silicon Films

Abstract

The growth mechanism of a hybrid process to crystallize amorphous silicon (a-Si) film was studied. In the process, a-Si was first converted to polycrystalline silicon (poly-Si) using Ni–metal-induced lateral crystallization (NILC), and then annealed with an excimer laser (ELA). Two regions based on different crystallization mechanisms were found on these NILC-ELA films: (A) a-Si melting region, and (B) a-Si/poly-Si melting region. In the a-Si melting region, the sizes and shapes of the needle Si grains were similar to those of NILC poly-Si. In the a-Si/poly-Si melting region, the shapes and sizes of poly-Si grains were quite different from those of NILC needlelike grains. Two crystallization regimes were found in the a-Si/poly-Si melting region: (1) geometrical coalescence regime and (2) complete melting regime. In the geometrical coalescence regime, the width of grains dramatically increased to 600 nm due to the geometrical coalescence of Si needle grains. However, in the complete melting regime, the NILC Si films melted completely. Small poly-Si grains were formed by homogeneous nucleation and growth.