| 摘要 |
PURPOSE:To accurately measure the phase shift quantity of a phase shifter film by detecting the positional deviation of an interference image by two luminous fluxes of a zero-order light beam which is transmitted through a test pattern provided on a photomask and a +1st order light beam or a -1st order light beam. CONSTITUTION:A light beam emitted from a light source 1 is made monochromatic and reaches the photomask 9 which should be inspected. The test pattern TP is formed on the lower surface of the photomask 9 besides a circuit pattern RP at the same producing stage as the RP. An irradiating light beam L3 is diffracted by the TP and the zero-order diffracted light beam L0, the +1st order diffracted light beam Lp, and the -1st order diffracted light beam Lm are generated. The three diffracted light beams are made incident on a detection optical system 11a and either the Lp or the Lm is shielded by light shielding members 12a and 12b and formed into the image on a detection means 13. The analysis of a light quantity signal obtained by the means 13 is performed in a control circuit 15 by setting the intensity distribution of the interference image at a best focusing position as reference so as to decide the positional deviation of the image. By thus measuring the phase shift quantity in the TP, the phase shift quantity in the RP is known. |
