Silicon film approximately 0.5 μm thick for gate electrodes in MOS devices was deposited at low temperatures (<100°C) by RF planar magnetron sputtering. The target was 99.9995% pure silicon, and the sputtering gas was argon (0.2–5.3 Pa). The deposited film was phosphorus implanted and thermally annealed in nitrogen atmosphere. Film properties were measured for as‐deposited film and annealed film. Film properties depend remarkably on argon pressure. As‐deposited film is amorphous at any argon pressure. At low argon pressure, the film consists of closely packed fine dense amorphous regions. As argon pressure increases, dense and porous regions become more pronounced and both regions increase in size. The resistivity of annealed film reaches a minimum at 2.0 Pa, the pressure at which as‐deposited film structure begins to change. The grain size also reaches a maximum at 2.0 Pa. At this pressure, it is possible to achieve low resistivity of less than , which is suitable for gate electrode in MOS devices. Moreover, MOS devices having excellent characteristics are successfully obtained using low temperature magnetron‐sputtered silicon films as gate electrodes.