Patent ID: 7795886

Claim:
A surface voltmeter for measuring a surface voltage on a semiconductor substrate on which an insulating film is formed, comprising: a substrate holding part for holding a semiconductor substrate; an electrode facing a measurement area on said semiconductor substrate in a noncontact manner and having transparency; a light source whose relative position to said substrate holding part is fixed; a reflective part which reflects light emitted from said light source and directs reflected light to an irradiation region including said measurement area through said electrode; a vibration part for vibrating said electrode in a vibration direction toward said measurement area, together with said reflective part; an electrode wiring which is electrically connected to said electrode and extends from said electrode in a direction away from said semiconductor substrate; and an operation part for obtaining a surface voltage on said measurement area on the basis of an electrode voltage applied to said electrode through said electrode wiring and a displacement current from said substrate holding part in vibrating said electrode or a displacement current from said electrode acquired through said electrode wiring in vibrating said electrode.