Patent ID: 8004678
Filing Date: 2011-08-23
Classification: G03F

Abstract:
1. A wafer alignment system, comprising: a radiation source to generate radiation; a radiation directing assembly to direct at least a portion of the radiation onto a surface of a wafer, the radiation having a polarization state; an optical analyzer to collect at least a portion of the radiation reflected from the wafer; the wafer including at least a first region having dummification pattern comprising a first grating pattern oriented in a first direction and at least a second region having a second grating pattern oriented in a second direction, different from the first direction and one or more registration features patterned on top of the dummification pattern, wherein the registration features comprise at least a first component that is parallel to the first direction and a second component that is parallel to the second direction, and wherein the dummification pattern comprises four regions of parallel lines, two of which are oriented in the first direction and two of which are oriented in the second direction, wherein the four regions intersect at a common central point; and the registration pattern comprises sets of lines oriented in the first direction and the second direction and centered about the common central point; and at least one set of lines forms a box centrally disposed about the intersection of the dummification pattern.