INSPECTING DEVICE FOR PHASE SHIFT MASK

摘要

PROBLEM TO BE SOLVED: To measure the phase amt. of a phase shifter with high accuracy without influenced by speckles and to improve the reliability. SOLUTION: UV laser beam emitted from a UV laser light source 10 is transmitted through a diffusion plate 30 which rotates around the optical axis of the UV laser beam, and the beam enters an illumination optical system 12. The beam is divided into two beams of linearly polarized beam having polarizing planes perpendicular to each other by the illumination optical system 12 to irradiate a phase shift mask 3. The two linearly polarized light beams transmitted through the phase shift mask 3 are overlapped by a detection optical system 20 to interfere with each other. The phase amt. of the phase shifter 2 of the phase shift mask 3 is determined based on the interference.