Asml Reticle Design Manual Work

Lithography is an inverse problem. A designer wants a square on the wafer. To get that square, the light source must be shaped differently, and the mask must have specific serifs or notches added to the corners. The manual dictates the Mask Error Enhancement Factor (MEEF) , which describes how errors on the mask are magnified on the wafer. A 1nm error on the mask might result in a 4nm error on the chip. The design manual sets the tolerances to prevent this runaway error.