METHOD OF MEASURING POSITION OF TWO-DIMENSIONAL PATTERN WITHHIGH PRECISION AND REFERENCE MASK

摘要

A method for high precision position measurement of two-dimensional structures such as structures on semiconductor wafers or masks, utilizing a reference mask having a two-dimensional grid, the relative position of the structures relative to the grid being identified by opto-electronic scanning using an image sensor and subsequent image processing. The absolute position of the structures to be measured can then be identified from the position of the grid elements. A reference mask is preferably employed whose grid elements carry a binary coding which can be read and decoded by the image processing means. The coding thereby indicates the position of the grid elements in the grid.