Patent ID: 7410919
Filing Date: 2008-08-12
Classification: H01L

Abstract:
1. A method for of aligning a mask to a substrate comprising in the order recited: (a) placing a bottom ring of an alignment fixture on an alignment tool; (b) loading a substrate onto a chuck; (c) securing said substrate on said chuck; (d) locating alignment targets on said substrate relative to fixed positions of a first X-Y stage and a rotational stage mounted on said first X-Y stage; (e) placing said mask on said bottom ring and placing a top ring of said alignment fixture on said mask, said top ring aligned to said bottom ring; (f) applying a clamping force of a first predetermined amount of force to said alignment fixture sufficient to prevent said mask from moving relative to said top and bottom rings; (g) locating alignment marks on said mask relative to a fixed position of a second X-Y-stage, said first X-Y stage and said table mounted to said second X-Y stage, X and Y orthogonal displacement directions associated with each of said first and second X-Y stages being co-aligned; (h) calculating an X distance in said X direction and a Y distance in said Y direction to move said first X-Y stage and an angle to rotate said rotational stage through in order to align said alignment marks to said alignment targets; (i) increasing the applied clamping force to a second predetermined amount of force, releasing said substrate from said chuck, and increasing the applied clamping force to a third predetermined amount of force; (j) temporarily fastening said alignment fixture containing said mask and said substrate together; and (k) releasing said applied clamping force.