PURPOSE: To provide high-efficiency and high-speed processing by providing high frequency to one of the two counter electrodes so that a pressure during processing is controlled to a specified level and by separating the substrate on the other electrode from plasma so that the substrate is prevented from being damaged due to ion impact.

CONSTITUTION: First, a substrate 2 comprising silicon is mounted on an electrode 3 at room temperature and a visible ultraviolet ray of a wavelength ranging from 200 to 800nm is irradiated from a light source 8 to the surface of the substrate. Next, a heater 4 is turned on and heated up to 300°C. Then, a SiH4 gas is supplied from a first gas port 6, a N2 gas is introduced from a second gas port 7, and the pressure inside the processing chamber is reduced to 1 to 100 Torr by a conductance valve set up on the side of an exhaust port 5. In this embodiment, the gas supplied from the first gas port 6 is passed directly through the vicinity of the body 2 and the gas supplied from the second gas port 7 is passed during plasma processing through the plasma generating region. Next, high-frequency power is supplied from a high-frequency power source 10 to an electrode 9, generating plasma in the vicinity of the electrode 9.