| CPC G01N 21/956 (2013.01) [G01N 21/47 (2013.01); G01N 21/95607 (2013.01); H01L 21/0271 (2013.01)] | 11 Claims |
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1. An apparatus for detecting a foreign matter on a substrate on which a pattern is formed, the apparatus comprising:
at least one processor; and
a memory coupled to the at least one processor, the memory having instructions that, when executed by the processor, causes the at least one processor to function as:
a detection unit including a light projector for projecting light on a surface of the substrate and a light receiver for receiving scattered light from the surface;
a change mechanism for changing an area of the projected light to a first area and a second area that is smaller than the first area without changing a light amount of the projected light and an angle of the projected light; and
a control unit for detecting the foreign matter based on a first light amount received by the light receiver in a case where the light is projected in the first area on the surface of the substrate and a second light amount received by the light receiver in a case where the light is projected in the second area on the surface of the substrate,
wherein the change mechanism is capable of switching about whether the first light amount is to be detected by the detection unit or the second light amount is to be detected by the detection unit,
wherein the control unit detects the foreign matter by comparing the first light amount and the second light amount that are from the same location on the surface of the substrate, and
the control unit compares the first light amount and the second light amount and determines that the foreign matter exists on the substrate in a case where the second light amount is greater than the first light amount.
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