Patent ID: 6200908
Filing Date: 2001-03-13
Classification: H01L

Abstract:
A process for reducing the waviness of a semiconductor wafer having a front surface and a back surface using plasma assisted chemical etching, the process comprising:measuring initial elevations at discrete positions on the front surface of the wafer relative to a reference plane other than the back surface, to produce a contour map of the front surface of the wafer independent from the back surface;selecting a target elevation for each discrete position relative to said reference plane based on a desired surface contour;determining the amount of stock to be removed at each of said discrete positions on the front surface of the wafer to reduce the initial elevation to the target elevation, said determination comprising use of an algorithm operating on the initial elevations and the target elevation and computing a dwell time versus position map for the front surface of the wafer to determine the length of time a plasma electrode must etch the front surface of the wafer; andremoving material selectively from the front surface of the wafer based on the dwell time versus position map by plasma assisted chemical etching to shape the front surface of the wafer to the target elevation.