Patent ID: 8130372

Claim:
A method of inspecting a surface of a wafer comprising: grasping a wafer at one or more selected regions around its periphery such that there is substantially no relative movement between a mechanism for grasping the wafer and the wafer; characterizing a deformation of the wafer due to+a manner in which the wafer is grasped; adjusting a focusing mechanism to ensure that images of the surface of the wafer remain substantially in-focus using data derived from the characterization of the wafer deformation; rotating the wafer about an axis substantially normal to the surface of the wafer while maintaining the wafer generally horizontal; capturing images of the surface of the wafer as the surface of the wafer is rotated past an imaging mechanism, wherein characterizing a deformation of a wafer comprises: modeling a predicted deformation of the wafer based at least in part on the physical properties of the wafer and at least one boundary conditions of a clamped grasped wafer; measuring at least some portion of an actual wafer to obtain shape data; and normalizing the model of the predicted deformation of the surface of the wafer using the shape data.