METHOD FOR INSPECTING PHASE SHIFT PHOTOMASK

摘要

PURPOSE:To directly and accurately measure the phase difference of a phase shifter in a short period of time without any damage using a simple arrangement and the same wavelength as wavelength in actual use. CONSTITUTION:A 1st light A with specific wavelength lambda1 is converged on the arrangement part of the phase shifter FS and a 2nd light B with wavelength lambda2 slightly different from the specific wavelength is converged on a part where the phase shifter FS is not arranged; and transmitted lights of both the parts are put one over the other and photoelectrically converted by a photoelectric converting element D2 and parts of the lights before being made incident on both the parts are split by a half-mirror HM respectively. Both the split lights A and B are put one over the other and photoelectrically converted by a photoelectric converting element D1 and the phase difference between the two photoelectrically converted signals I1 and I2 is detected to measure the phase difference between both the parts.