Microwave-induced low-temperature crystallization of amorphous silicon thin films

Abstract

Microwave heating was utilized for solid phase crystallization of amorphous silicon films. The amorphous silicon thin films were deposited in the temperature range of 100-400 degrees C by plasma enhanced chemical vapor deposition and annealed by microwave healing at 550 degrees C in nitrogen. Microwave beating lowered the annealing temperature and reduced the annealing time for complete crystallization. For example, the a-Si film deposited at 400 degrees C was fully crystallized in 3 h at 550 degrees C. On microwave heating. the hydrogen in the amorphous films diffused out very quickly, but there was no change in structural disorder following hydrogen evolution. The lower temperature crystallization of a Si films compared to conventional furnace annealing is due to the interaction between microwave and silicon atoms. The grain size of the crystallized silicon films was in the range of 0.55-0.78 mu m, depending on the deposition temperature. These grain sizes are not so small compared to those of Si films crystallized by conventional furnace heating, while the crystallization time is much shorter. (C) 1997 American Institute of Physics.