Effect of ramp annealing to Ni induced lateral crystallization of amorphous silicon

Nickel Metal-Induced-Lateral-Crystallization (MILC) has been used to enlarge the grain size and improve the quality of(poly-Si) Thin-Film-Transistors (TFTs). However, the MILC temperature is still low and the grain size is still small. The feasibility of forming very large grains (single crystal like) from amorphous silicon (a-Si) by combining MILC with ramp annealing has been studied. It has been found that the grain size after ramp annealing is remarkably enhanced and can reach of the order of several ten's of microns. The velocity of MILC with ramp annealing is faster than that of MILC with isothermal annealing. The grain size becomes maximal at around 625°C/2hrs, and saturates at higher temperatures of 625-1000°C. The effect of temperature, time and other parameters has also been studied in order to maximize the grain size and quality. MILC with ramp annealing at 625°C can greatly lower the process time and reduce the need of subsequent annealing to enhance the grain size. The new technology can have numerous novel applications such as providing a low cost alternative to form silicon-on-insulator (SOI) substrates and a breakthrough for high performance TFTs and novel multi-layers SOI like devices and circuits