Pattern inspection apparatus, focus position adjustment method, and pattern inspection method

A focus position adjustment method, comprising:

• creating, using an autofocus signal used as a parameter for autofocus control for each height position and a focus evaluation value for evaluating a focus position for the each height position, correlation data between the autofocus signal and the focus evaluation value, the autofocus signal and the focus evaluation value being acquired while changing a height position of a pattern formation surface of an evaluation substrate formed with an evaluation pattern with the evaluation substrate placed on the stage;
• storing the correlation data in a storage device;
• calculating an inspection autofocus signal for acquiring a focus evaluation value equal to or greater than a threshold value for an inspection target substrate formed with a figure pattern, using the autofocus signal and the focus evaluation value for each height position acquired while changing a height position of a pattern formation surface of the inspection target substrate with the inspection target substrate placed on the stage and the correlation data obtained from the evaluation substrate;
• and
• adjusting, in a case of capturing an optical image of the inspection target substrate with a sensor by receiving light transmitted through or reflected from the inspection target substrate irradiated with inspection light, the height position of the pattern formation surface of the inspection target substrate to a height position of the pattern formation surface corresponding to a value of the inspection autofocus signal.

A pattern inspection method, comprising:

• creating, using an autofocus signal used as a parameter for autofocus control for each height position and a focus evaluation value for evaluating a focus position for each height position, correlation data between the autofocus signal and the focus evaluation value, the autofocus signal and the focus evaluation value being acquired while changing a height position of a pattern formation surface of an evaluation substrate formed with an evaluation pattern with the evaluation substrate placed on the stage;
• storing the correlation data in a storage device;
• calculating an inspection autofocus signal for acquiring a focus evaluation value equal to or greater than a threshold value for an inspection target substrate formed with a figure pattern, using the autofocus signal and the focus evaluation value for each height position acquired while changing a height position of a pattern formation surface of the inspection target substrate with the inspection target substrate placed on the stage and the correlation data obtained from the evaluation substrate;
• capturing an optical image of the inspection target substrate with a sensor by receiving light transmitted through or reflected from the inspection target substrate irradiated with inspection light while adjusting the height position of the pattern formation surface of the inspection target substrate to a height position of the pattern formation surface corresponding to a value of the inspection autofocus signal;
• and
• comparing a captured optical image with a reference image and outputting a result of the comparison.