| 摘要 |
PURPOSE:To enable highly accurate detection of a defect, by projecting laser light to an object to be inspected from a projector section to separate the defect distinctly from dust. CONSTITUTION:First, a defect inspection coordinate is determined on a water 1 by control signals SC1 and SC2 from a control section 8 and laser light 3 is projected onto the water 1 from a projector section 4. When dust or a defect exists on the wafer 1, scattered beams of light 19 and 23 are received by photodetectors 21 and 25 to be converted into electrical signals SP1 and SP2, which then, are converted into binary codes signals SB1 and SB2 with binary coding circuits 29 and 30, the signal SB2 is inverted with an inverter 31 and an inversion signal SI is outputted to an AND gate 32 together with the signal SB1. A defect signal SD is outputted to the control section 8 from an AND gate 32. When dust exists on the wafer 1, the scattered light 23 is received by both the devices 21 and 25. The signals SB1 is SI of logical levels '1' and '0' respectively are inputted into to the gate 32 and the logical level of the defect signal SD moves to '0' indicating no defect. |
