Patent ID: 9547233
Date: 2017-01-17
CPC Classifications: G03F

Claim:
1. A computer-implemented method for determining a set of surface profiles, comprising: receiving a surface profile of a surface in a multilayer stack of a reflective photomask, wherein such surface profile was obtained by measuring a top surface of the multilayer stack or a top surface of a substrate underneath such multilayer stack using a microscopy tool to obtain a multi-value grayscale or bitmap representation of such surface; calculating a second surface profile of a second surface in the multilayer stack based on a generalized Eikonal equation, a geometry of the multilayer stack and the surface profile, wherein the second surface is associated with a different layer in the multilayer stack than the surface, and wherein the second surface is adjacent to the surface in the multilayer stack; repeating, one or more times, the calculation operation for additional surfaces in the multilayer stack based on a generalized Eikonal equation, a geometry of the multilayer stack, the surface profile, and surface profiles determined in preceding instances of the calculation operation, thereby determining the set of surface profiles, wherein a given additional surface is associated with a different layer in the multilayer stack than the surface profile and the surface profiles determined in preceding instances of the calculation operation, and wherein the given additional surface is adjacent to another surface in the multilayer stack that is associated with another layer in an immediately preceding instance of the calculation operation, and wherein the surface profile is used as a boundary condition in calculating the set of surface profiles; based on the set of surface profiles, indicating whether the multilayer stack of the photomask will result in a printable defect on a semiconductor wafer during a photolithography process and such photomask requires a remedial action to repair the photomask; and performing the remedial action to repair the photomask if it is indicated that the multilayer stack will result in a printable defect.