Patent ID: 8067753

Claim:
An electron beam writing apparatus which has a holding mechanism for holding a mask at a back surface thereof and applies an electron beam onto a surface of the mask held by the holding mechanism by electron beam applying means thereby writing a desired pattern, comprising: an XY stage movable in a direction orthogonal to the direction of an optical axis of the electron beam; an electron-beam focal adjusting mark table fixed onto the XY stage; a Z stage mounted onto the XY stage in avoidance of an area to which the mark table is fixed, and movable in the optical axis direction; and measuring means for measuring a height of the mark table and a height of the mask placed on the holding mechanism, wherein the electron beam applying means includes a focal adjustment mechanism for varying a focal height of the electron beam within a predetermined adjustable range and a middle value of the adjustable range coincides with the height of the mark table, wherein the mask holding mechanism includes difference calculating means placed on the Z stage for calculating a difference between the height of the mark table measured by the height measuring means and the height of the mask placed on the holding mechanism, and Z stage control means for moving the Z stage based on information about the calculated difference in such a manner that the height of the mask coincides with the height of the mark table, and wherein the height of the mask used in the calculation of the difference calculating means is a middle value between highest and lowest values of heights of a plurality of measurement points, which are obtained by measuring the plurality of measurement points on the mask by the height measuring means.