Patent attributes
In a surface voltmeter (1), a surface voltage on a measurement area on a semiconductor substrate (9) on which an insulating film is formed is measured while applying light to the measurement area. With this operation, a voltage induced on a main body of the substrate (9) by charge which is charged on a surface of the insulating film is balanced out. Consequently, it is possible to measure a surface voltage on the measurement area with high accuracy. Since an electrode wiring (164) used for application of an electrode voltage to an electrode (12) extends from the electrode (12) in a direction away from the substrate (9) along a vibration direction, it is possible to prevent influences of noises caused by vibration of the electrode wiring (164) in vibrating the electrode (12) and to measure the surface voltage on the measurement area more accurately.
