Patent ID: 7940374
Filing Date: 2011-05-10
Classification: G03B,G03F

Abstract:
1. A method of compensating for process errors in a lithography tool, comprising: measuring at least one feature of a first surface of a wafer at a desired mapping speed and at a desired accuracy with a first sensor to selectively map a topography of the wafer; measuring the wafer in parallel with the measuring of the at least one feature with a second sensor to determine focus-positioning parameters of an exposure system; calibrating one or more sources of the process errors in the focus-positioning parameters associated with the second sensor using the at least one feature of the first surface measured using the first sensor; measuring a first full-density field map of the wafer with the first sensor to obtain first-sensor data; and measuring a second full-density field map of the wafer with the second sensor to obtain second-sensor data for determining an intrafield error.