Patent ID: 8718432

Claim:
A method comprising: providing a first layer of a first material, wherein the first material etches at a first etch rate in a first etchant; providing an accelerator layer disposed on the first layer, the accelerator layer comprising a second material, wherein the second material etches at a second etch rate in the first etchant; providing a mask layer, wherein the mask layer is disposed on the accelerator layer in a first region, and wherein the mask layer is provided such that it comprises a field region and a wedge region that extends from the field region along a first lateral direction, the wedge region having a first edge and a second edge; laterally etching the accelerator layer in the first etchant such that the wedge region is undercut along the first lateral direction and such that the first layer is exposed to the first etchant for a longer period of time at a first point that at a second point; laterally etching the accelerator layer in the first etchant such that the wedge region is undercut along a second lateral direction that is normal to the first edge and a third lateral direction that is normal to the second edge, wherein the first lateral direction, second lateral direction, and third lateral direction are non-parallel and non-orthogonal; and etching the first layer in the first region in the first etchant such that the thickness of the first layer increases monotonically from each of (1) the first point to the second point, (2) a third point to a fourth point along the second lateral direction, and (3) a fifth point to a sixth point along the third lateral direction.