Patent ID: 6433352
Filing Date: 2002-08-13
Classification: G03F

Abstract:
A method of positioning a semiconductor wafer, the method comprising:fixing a semiconductor wafer on a wafer stage, the semiconductor wafer including a plurality of shot areas regularly arranged thereon, and positioning each of the shot areas in turn in an exposure position by a step and repeat system, determining warpage of the semiconductor wafer using a plurality of linearly arranged alignment marks, wherein a first of the plurality of alignment marks is on a boundary of the shot area at the center of the semiconductor wafer and a last of the plurality of alignment marks is provided outside a shot area provided at the periphery of the semiconductor wafer and is the alignment mark of the plurality furthest from the center of the wafer, and total warpage magnitude is determined for the last alignment mark relative to a central area of the wafer; and distributing the total warpage determined to the plurality of linearly arranged alignment marks in a manner so that warpage magnitude between pairs of adjacent alignment marks progressively increases moving away from the center of the wafer so that warpage magnitude distributed between second and third adjacent alignment marks of the plurality is less than warpage magnitude distributed between the third and a fourth alignment mark of the plurality, where the second, third and fourth alignment marks are located progressively further from the center of the wafer; wherein a step pitch to move each of the shot areas to the exposure position is adjusted by a magnitude of warpage of the semiconductor wafer.