Optical-type foreign matter inspection device

An optical-type foreign matter inspection device for inspecting a foreign matter on a surface of a sample, the optical-type foreign matter inspection device comprising:

• a rotation stage configured to allow the sample to be placed thereon and rotate the sample about a rotation axis;
• a translation stage configured to move the rotation stage within a horizontal plane with the rotation axis as a vertical direction;
• a laser light source configured to irradiate the surface of the sample with a laser beam;
• a variable optical attenuator configured to adjust laser power of the laser beam with which the surface of the sample is irradiated by being inserted in an optical path of the laser beam;
• a first optical sensor configured to receive the laser beam transmitted through the variable optical attenuator and output a first detection signal according to a received light amount;
• a laser power monitor configured to measure the laser power with which the surface of the sample is irradiated based on the first detection signal;
• a second optical sensor configured to receive light scattered or reflected from the surface of the sample and output a second detection signal according to a received light amount;
• and
• a controller configured to control the optical-type foreign matter inspection device, wherein
• the controller
• stores, as control information, a setting value of the laser power for each coordinate within the horizontal plane in the translation stage and a control amount of the variable optical attenuator,
• controls, based on the control information, the laser power using the control amount of the corresponding variable optical attenuator for each coordinate within the horizontal plane, and
• calculates, for each coordinate within the horizontal plane, an error between a measurement value of the laser power that is measured by the laser power monitor and the setting value of the laser power in the control information, and corrects a control amount of the variable optical attenuator in the control information based on the calculated error.