The high-density and low-temperature microwave plasma (2.45 GHz) utilizing a spoke antenna was applied for fast deposition of hydrogenated microcrystalline silicon (μc-Si : H) film. Highly crystallized and photoconductive, μc-Si : H film was fabricated under the plasma condition that the electron density n_e show the maximum together with the minimum of the “hot electron population”. The precise control of the ion beam energy impinging to the growing surface was very effective for the promotion of the film crystallinity. High rate deposition of μc-Si : Hfilm was also achieved at 47 Å/s from the 30 sccm SiH₄ plasma. This high-density microwave plasma has a high potential not only for etching but also for the large-area thin film deposition processes such as solar cell and thin film transistors (TFTs).