Abstract: A position detecting apparatus for a semiconductor wafer includes a wafer worktable supported by an X-Y stage. The worktable is rotatable about an axis on a reference center for positioning the wafer. The apparatus also includes a photoelectric sensor arranged to correspond to the edge region of the wafer on the worktable. The photoelectric sensor includes an infrared-ray emitting LED and a collimator lens for applying a parallel luminous flux to the wafer edge region, and a photo diode facing the collimator lens through the wafer edge region, all arranged on the optical axis. The photo diode outputs a signal having a level corresponding to a received light quantity. The photoelectric sensor also includes a light shielding slit plate having a slit arranged on the optical axis.

Abstract: A testing apparatus for an opening state of a hole in a semiconductor device includes a laser light radiating system. The semiconductor device has the conductive layer and the insulating layer formed on the conductive layer, and the hole is formed in the insulating layer at aim to reach the conductive layer. The laser light radiating system radiates to a hole, a laser light having a wave length determined based on a work function of a material of a conductive layer and a work function of a material of an insulating layer. A detector detects photoelectrons emitted through a portion of the hole to which the laser light is irradiated. A charge supplementing mechanism supplies electrons to the conductive layer.