PURPOSE: To suppress the generation of particles from the surface of a bias electrode in an ion implantation device.
CONSTITUTION: A Faraday cup 2 is arranged directly before a semiconductor wafer W on a rotational disc 17, and a semiconductor film 6 such as SiC is formed on the surface (the surface of the inside) of a conductor 5 such as carbon, in the side of the Faraday cup 2 into which an ion beam penetrates, while two bias electrodes 3A, 3B(3) are provided. The inner wall surface of each of these electrodes is formed into circle. A bias voltage of -2KV, for example, is applied to the bias electrodes 3 so that no electron jumps out from the outside of the Faraday cup 2. Sputtered grains from the surface of a wafer W are adhered to the surface of the bias electrodes 3, and an insulating film is thus formed. Electric discharge is prevented due to the resistance of a semiconductor, even when positive charges are stored on the surface of the insulating film and exceed the withstand charge amount of the insulating film, and the generation of particles can thus be suppressed.
KIKUCHI SHUJI
TOMOYASU MASAYUKI