Patent ID: 7365408

Claim:
A structure for photolithographic processing, comprising: a wafer forming a foundation upon which other layers may be fabricated, the wafer having a non-planar surface; a conductive layer formed directly in contact with the wafer, the conductive layer having a stepped surface formed by different thicknesses of conductive material along the surface of the wafer; a two-layer anti-reflective structure disposed on and in contact with the conductive layer, the two-layer anti-reflective structure having a substantially uniform thickness along the non-planar surface of the conductive layer, the two-layer anti-reflective structure comprising: a first layer of a dielectric material formed with a substantially constant first thickness on and in contact with the conductive layer, the first layer of a dielectric material extending along the surface of the conductive layer and contouring with the stepped surface of the conductive layer; and a second layer of absorption material formed with a substantially constant second thickness on and in contact with the first layer of dielectric material, the second layer of absorption material extending along the surface of the first layer of a dielectric material and contouring with the surface of the first layer of a dielectric material; and a photoresist layer formed on and in contact with the second layer of absorption material and having a thickness that varies inversely to the change in thickness of the wafer such that the top surface of the photoresist layer is parallel to the bottom surface of the wafer; wherein the first thickness of the first layer of a dielectric material and the second thickness of the second layer of absorption material are selected to optimize the cummulative anti-reflection property of the two-layer anti-reflective structure by choosing the first thickness of the first layer of a dielectric material and the second thickness of the second layer of absorption material to intersect on a reflectance contour graph for the first layer of dielectric material and the second layer of absorption material to fully absorbed light between the conductive layer and the photoresist layer.