Patent ID: 9679821
Date: 2017-06-13
CPC Classifications: G01B,G03F,H01L

Claim:
1. A method of revising overlay correction data, comprising: preparing a plurality of wafers each having a plurality of overlay coordinates in a plurality of shot areas, wherein the plurality of shot areas include mutually exclusive first and second shot area groups, the overlay coordinates include first and second mutually exclusive overlay coordinate groups, and the wafers include first and second mutually exclusive wafer groups; forming overlay keys on the overlay coordinates in the shot areas of the wafers by performing a photolithography process using first overlay correction data; selecting a first wafer from the first wafer group, measuring first overlay errors of the overlay keys on the first overlay coordinate group in the shot areas of the first shot area group on the first wafer, and performing a first revision of, or revising primarily, the first overlay correction data using the first overlay errors; and selecting a second wafer from the second wafer group, measuring second overlay errors of the overlay keys on the second overlay coordinate group in the shot areas of the second shot area group on the second wafer, and performing a second revision of, or revising secondarily, the primarily revised first overlay correction data using the second overlay errors.