Rapid Thermal Annealing of Amorphous Silicon Thin Films Grown by Electron Cyclotron Resonance Chemical Vapor Deposition

Hydrogenated amorphous silicon (a-Si:H) thin films were deposited on pre-oxidized Si wafers by electron cyclotron resonance chemical vapor deposition (ECRCVD). The rapid thermal annealing (RTA) treatments were applied to the as-grown samples in nitrogen atmosphere, and the temperature range for the RTA process is from 450 to 950 °C. The crystallization and grain growth behaviors of the annealed films were investigated by Raman spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The onset temperature for the crystallization and grain growth is around 625 ∼ 650°C. The crystalline fraction of annealed a-Si:H films can reach ∼80%, and a grain size up to 17 nm could be obtained from the RTA treatment at 700 °C. We found that the crystallization continues when the grain growth has stopped.