PATTERN JUDGING METHOD, MASK PRODUCING METHOD, AND METHOD OF DIVIDING BLOCK PATTERN FOR USE IN BLOCK EXPOSURE

A method of dividing a block pattern for use in a block exposure, to be implemented on a computer, divides an arbitrary block which is to be formed in a block mask that is used for the block exposure when the arbitrary block is judged as including a prohibiting pattern which is undesirable from a point of view of the block exposure. This method comprises the steps of (a) dividing the arbitrary block in a first direction to obtain a first block having a first dividing width along a second direction which is perpendicular to the first direction, (b) dividing a remaining block portion of the arbitrary block excluding the first block in the first direction to obtain a first divided portion having a second dividing width along the second direction, and merging the first dividing portion to the first block if the second dividing width is less than a predetermined width, and (c) searching the first block in the first direction after the step (b) and merging one of two adjacent first patterns within the first block to a second block if a pattern interval which is less than a predetermined value extends along the first direction between the first patterns.