METHODS FOR MEASURING OVERLAYS

摘要

A method for measuring overlay includes receiving a first image of a first overlay mark captured using light having a first wavelength. The method includes receiving a second image of a second overlay mark captured using light having a second wavelength different from the first wavelength. The method includes measuring a displacement between a central portion of the first image and a central portion of the second image, wherein the first and second overlay marks are disposed on different levels.

主权项

1. A method for measuring overlay, the method comprising:
receiving a first image of a first overlay mark selectively captured using light having a first wavelength in a first step; receiving a second image of a second overlay mark selectively captured using light having a second wavelength different from the first wavelength in a second step different from the first step; and measuring a displacement between a central portion of the first image and a central portion of the second image, wherein the first and second overlay marks are disposed on different levels, wherein:
the first overlay mark comprises a plurality of first zones comprising a first pattern disposed along an x direction, a second pattern disposed along a y direction, a third pattern disposed along the x direction and a fourth pattern disposed along the y direction, wherein the first through fourth patterns are rotationally symmetric around a center of the first overlay mark, andthe second overlay mark comprises a plurality of second zones comprising a fifth pattern disposed along an x direction, a sixth pattern disposed along a y direction, a seventh pattern disposed along the x direction and an eighth pattern disposed along the y direction, wherein the fifth through eighth patterns are rotationally symmetric around a center of the second overlay mark.