Patent ID: 7408642
Filing Date: 2008-08-05
Classification: G03F

Abstract:
1. A target for use in measuring the relative position between two substantially coplanar layers of a device wherein a second layer of said two layers is located on a first layer of said two layers and for measuring an image placement error of each layer, the target comprising: a first ring structure to be placed on said first layer of said device that is visible through said second layer; a first periodic structure to be placed on said first layer of said device within said first ring structure, wherein said first periodic structure is visible through said second layer; a second periodic structure that complements said first periodic structure with said second periodic structure placed on said second layer of said device at a location that is adjacent said first periodic structure within said first ring structure when said second layer is placed on said first layer with said first and second layers being in fixed position with respect to each other; and a second ring structure that complements said first ring structure with said second ring structure placed on said second layer of said device within said first ring structure and with said first and second periodic structures being located within said second ring structure.