Patent ID: 7407891

Claim:
A method for improving the geometry of a semiconductor wafer having a device surface and a back surface, prior to fabrication of electronic devices on the device surface, the wafer having at least one of thickness variation, edge roll-off, global flatness or local flatness as geometry imperfections, comprising: a) providing a plurality of semiconductor wafers; b) measuring at least one parameter which characterizes the geometry imperfection in a position dependent manner across a whole wafer surface and determining a position dependent value of the parameter; c) from the position dependent parameter value, creating for each individual wafer a grayscale of position dependent light intensity respectively related to the position dependent parameter values; d) simultaneously illuminating a whole wafer surface with said grayscale of light intensity while etching the surface so illuminated in an etching medium, the position dependent material removal rate increasing at position dependent higher light intensity such that a wafer having an improvement in geometry imperfection is obtained thereby.