| 摘要 |
PURPOSE:To measure the relative gradient successfully regardless of the gradient optical axis of projection lens by a method wherein the relative gradient between the wafer surface and the projection image-formed surface of a mask pattern is calibrated making reference to the gradient of projected substrate surface to the specified reference surface. CONSTITUTION:In order to make the surface (mirror face) 3 of semiconductor wafer and the projection image-formed surface FR of a mask pattern relatively gradient, the parallel light flux from a light emitting system 19 is reflected on the mirror face 3 to be entered into a light receiving system 20. At this time, a plane parallel 21 is adjusted so that a spot SP may be image-formed on a specified position. Next a stage 2 is lifted to maximize the contrast between masks 9 and 11 for measuring the shifting amount. Finally the relative gradient between the projection image-formed surface and the wafer surface can be measured making reference to the shifting amount, the distance between masks 9 and 11 and the adjusted value of plane parallel 21. |
