Surface Inspection Method and Surface Inspection Apparatus

A surface inspection method for detecting contaminant particles and defects present on a surface of an object to be inspected or in the interior of the object to be inspected in the vicinity of the surface by irradiating a region of a predetermined size on the surface of the object to be inspected with an irradiation beam, comprising:

• a photodetection step that involves detecting light that derives from the irradiation beam and is scattered, diffracted or reflected on the surface of the object to be inspected or in the vicinity of the surface by use of a plurality of photodetectors arranged so as to perform detection in the directions of a plurality of elevation angles or a plurality of azimuthal angles or a combination of a plurality of elevation angles and a plurality of azimuthal angles with respect to the surface of the object to be inspected, and converting the light into electrical signals;
• a signal processing step that involves dividing output electrical signals from each of the photodetectors into signals for at least two systems, processing a signal for one system through a low-pass filter so as to take out a first signal component corresponding to the intensity of light generated by deriving from roughness of the surface of the object to be inspected, which belongs to the light scattered, diffracted or reflected from the surface of the object to be inspected or in the vicinity of the surface, and processing a signal for the other system through a band-pass filter so as to take out a second signal component corresponding to the intensity of light generated by deriving from a contaminant particle and a defect on the surface of the object to be inspected or in the vicinity of the surface, which belongs to the light scattered, diffracted or reflected from the surface of the object to be inspected or in the vicinity of the surface;
• a step of amplifying the second signal component at an amplification rate that is inversely proportional to the first signal component;
• a step of converting the second signal component after amplification into digital data;
• and
• a particle-size calculation step that involves performing weighted addition processing or weighted averaging processing by linear combination for a plurality of digital data corresponding to signals detected by the plurality of photodetectors and calculating the size of a contaminant particle and a defect from results of the weighted addition processing or weighted averaging processing.

A surface inspection apparatus, comprising:

• beam irradiation means that irradiates a region of a predetermined size on a surface of an object to be inspected with a beam;
• an inspection object moving stage that relatively moves the object to be inspected with respect to the beam;
• a photodetection system that detects light that derives from the irradiation beam and is scattered, diffracted or reflected on the surface of the object to be inspected or in the vicinity of the surface, and converts the light into an electrical signal;
• an A/D converter that converts the electrical signal into digital data;
• and
• a particle-size calculation part that calculates the size of a contaminant particle and a defect from the digital data,
• wherein the photodetection system simultaneously or virtually simultaneously detects an electrical signal or digital data that expresses the intensity of scattered light generated by deriving from microroughness of the surface of the object to be inspected, which belongs to the light scattered, diffracted or reflected from the surface of the object to be inspected or in the vicinity of the surface, and an electrical signal or digital data that represents the intensity of light generated by deriving from a contaminant particle and a defect on the surface of the object to be inspected or in the vicinity of the surface, which belongs to the light scattered, diffracted or reflected from the surface of the object to be inspected or in the vicinity of the surface, in the directions of a plurality of elevation angles or a plurality of azimuthal angles or a combination of a plurality of elevation angles and a plurality of azimuthal angles with respect to the surface of the object to be inspected.

A surface inspection apparatus, comprising:

• beam irradiation means that irradiates a region of a predetermined size on a surface of an object to be inspected with a beam;
• an inspection object moving stage that relatively moves the object to be inspected with respect to the beam;
• a photodetection system that detects light that derives from the beam and is scattered, diffracted or reflected on the surface of the object to be inspected or in the vicinity of the surface by use of a plurality of photodetectors arranged so as to perform detection in the directions of a plurality of elevation angles or a plurality of azimuthal angles or a combination of a plurality of elevation angles and a plurality of azimuthal angles with respect to the surface of the object to be inspected, and converts the light into electrical signals;
• a plurality of A/D converters that convert the electrical signal obtained from the plurality of photodetectors into digital data;
• and
• a particle-size calculation part that calculates the size of a contaminant particle and a defect from the digital data,
• wherein the particle-size calculation part calculates the size of the contaminant particle and the defect by applying the digital data to a calibration curve prepared beforehand by correlating the size of a contaminant particle and a defect to the value of the digital data corresponding to the contaminant particle and the defect for each of the plurality of photodetectors.