Polycrystalline silicon (poly-Si) thin films were prepared by a remote microwave plasma-enhanced chemical vapor deposition technique at low temperatures using SiF4and H2 as reactive gases.It was found that the impact of the charged particles in the plasma on the growing surface significantly affects the surface reactions and the crystallinity of the resultant films.By applying the bias on the substrates to decelerate the particles,high-quality poly-Si films, with hydrogen content less than 0.9 at% and the FWHM of 520 cm-1 Raman peak as narrow as 4.4 cm-1,have been obtained at a low temperature of 360℃.