SURFACE INSPECTING DEVICE

摘要

PURPOSE:To obtain an inspecting device less susceptible to a deterioration in parts of the equipment or the like, by projecting a light beam slantly to a area to be scanned of a surface to be inspected to detect hourly changes in an output signal with the photoelectric conversion of the scattered light thereof. CONSTITUTION:A light beam from a light source 16 is projected slantly to the surface of a semiconductor wafer 10 on a rotary stage 12 through a lens 18. The scattered light from the surface of the wafer 10 passes through an objective lens 20 to be incident into a linear image sensor 24 having fifty pixels. Output signals of the sensor 24 are inputted into corresponding fifty hourly change detection circuits 26 and a voltage proportional to an absolute value of a difference between output signals from the sensor 24 and a sample holding circuit 28 is outputted from a difference detection circuit 30. A comparator 32 compares an output voltage of the circuit 26 with a threshold voltage. A comparator 40 compares an output voltage of the sensor 24 with a threshold voltage. The outputs thus compared are outputted as final foreign matter detection signal at an OR gate 44 via an OR gate 34 and an AND gate 36 or an OR gate 42 respectively.