Abstract: The invention relates to a device for contacting and electrically grounding semiconductor substrate coated with or otherwise having an insulating film positioned thereover. The device includes a chuck having a wafer support surface which holds the wafer and a scriber movably attached to the chuck. The scriber is configured to contact the wafer through an opening in the chuck and to produce a perforation through the insulating film. The device further includes an electrically conductive probe movably attached to the chuck and configured to be moved into an access opening in the chuck to contact the semiconductor substrate through the perforation. Thus, the device increases the accuracy of open circuit type measurements of the wafer surface potential, particularly for Kelvin and Monroe electrode measurements of electrical properties of insulating films on semiconductor substrates.