Hybrid Phase Unwrapping Systems and Methods for Patterned Wafer Measurement

摘要

Systems and methods for unwrapping phase signals obtained from interferometry measurements of patterned wafer surfaces are disclosed. A phase unwrapping method in accordance with the present disclosure may calculate a front surface phase map and a back surface phase map of a wafer, subtract the back surface phase map from the front surface phase map to obtain a phase difference map, unwrap the phase difference map to obtain a wafer thickness variation map, unwrap the back surface phase map to obtain a back surface map representing the back surface of the wafer; and add the wafer thickness variation map to the back surface phase map to calculate a front surface map representing the front surface of the wafer.

主权项

1. A method, comprising:
acquiring at least one image of a front surface of a wafer and at least one image of a back surface of the wafer; calculating a front surface phase map for the wafer based on the at least one image of the front surface of the wafer; calculating a back surface phase map for the wafer based on the at least one image of the back surface of the wafer; subtracting the back surface phase map from the front surface phase map to obtain a phase difference map; phase unwrapping the phase difference map to obtain a wafer thickness variation map; phase unwrapping the back surface phase map to obtain a back surface map representing the back surface of the wafer; and adding the wafer thickness variation map to the back surface phase map to calculate a front surface map representing the front surface of the wafer.