Enhanced Grain Growth Phenomena in Excimer Laser Annealed Microcrystalline Silicon Films

In this work we have investigated the feasibility of microcrystalline silicon as the precursor material for the formation of high crystalline quality polysilicon films. Excimer laser anneal (ELA) process was used for the phase transformation of amorphous to polycrystalline silicon (polysilicon). Polysilicon films, obtained from laser annealed microcrystalline silicon, were found to demonstrate larger grain size than that of laser annealed amorphous silicon films. This grain size enhancement was attributed to an improved microstructure developing during the initial, rapid, solid-phase-crystallization (SPC) stage, preceding the melting process, during laser anneal. Proper engineering of the as-deposited film structure, via optimization of deposition conditions, yielded a twofold increase in the grain size of the post ELA polysilicon films. Based on the findings of this work, one direction for additional improvement is suggested by employing alternative deposition methods that allow for greater control of the as-deposited film structural characteristics.