Electron beam direct writing system for ULSI lithography with facilitated rotation and gain corrections of shot patterns and electron beam direct writing method for same

An electron beam direct writing method for use in an electron beam drawing apparatus including an electron gun for supplying an electron beam, a first and a second aperture member vertically aligned for obtaining a desired rectangular pattern, a deflector as an electro-optical shaping lens interposed between the first and the second aperture member for creating a rectangular pattern of a desired size, and an objective for having the electron beam, as it has passed through the second aperture member, focused on a surface of a semiconductor substrate as an object of a mapping operation, the method comprising:

• a pattern forming step of forming a first, a second, and a third shot pattern and an evaluation pattern by the second aperture member, including mapping on the semiconductor substrate the first shot pattern of a rectangular figure having a predetermined size, the second shot pattern adjacent to the first shot pattern in a first direction and the third shot pattern adjacent to the first shot pattern in a second direction perpendicular to the first direction, mapping a first line/interval pattern by arranging short lines each having a predetermined width at first pitches in the first and the second direction in peripheral portions of the first shot pattern and mapping second line/interval patterns by arranging short lines in the first and the second direction in peripheral portions respectively of the second and the third shot pattern at second pitches slightly different from the first pitches and cooperative with the first pitches to establish a main/auxiliary scale relationship therebetween;
• a first positional difference detecting step of attaining a value in ordinal number of a matching line where a positional matching occurs between short lines respectively of the first line/interval pattern and either of the second line/interval patterns, the value in ordinal number being determined relative to a central line;
• a second positional difference detecting step of attaining a value in ordinal number of a matching line where a positional matching occurs between short lines respectively of the first line/interval pattern and the other of the third line/interval patterns, the value in ordinal number being determined relative to a central line;
• and
• a multiplying step of multiplying each of the values in ordinal number by a resolution of the main/auxiliary scale relationship determined from the first and the second pitches, thereby detecting real dimensional errors between the first, the second, and the third shot pattern.