Pattern inspection apparatus

A pattern inspection apparatus comprising:

• a first half-wave plate configured to receive an ultraviolet light linearly polarized in a first electric field oscillation direction, and output a linearly polarized light polarized in a second electric field oscillation direction obtained by rotating the first electric field oscillation direction of the ultraviolet light by an integer multiple of 90°;
• a mirror configured to reflect the linearly polarized light polarized in the second electric field oscillation direction, and output a linearly polarized light polarized in a third electric field oscillation direction parallel or orthogonal to the second electric field oscillation direction;
• a second half-wave plate configured to convert the linearly polarized light polarized in the third electric field oscillation direction, which has been reflected, to a linearly polarized light polarized in a fourth electric field oscillation direction by rotating the linearly polarized light polarized in the third electric field oscillation direction by an angle different from an integer multiple of 90° so as to output the linearly polarized light polarized in the fourth electric field oscillation direction;
• a stage configured to mount thereon a substrate, on which a repetitive pattern having a size smaller than a resolution limit of the ultraviolet light is formed, such that the repetitive pattern is repeated in a direction parallel or orthogonal to the third electric field oscillation direction;
• an objective lens configured to make the linearly polarized light rotated in the fourth electric field oscillation direction by the second half-wave plate illuminate the repetitive pattern formed on the substrate;
• and
• a sensor configured to receive a transmitted light of the repetitive pattern smaller than the resolution limit or a reflected light from the repetitive pattern smaller than the resolution limit, which has been irradiated with the linearly polarized light polarized in the fourth electric field oscillation direction obtained by rotating the third electric field oscillation direction by the angle different from the integer multiple of 90° by the second half-wave plate.