Patent ID: 7780867

Claim:
A method of removing unwanted copper metal from an edge bevel area of a semiconductor wafer, the method comprising: (a) providing a wafer having a layer of electrodeposited copper in the interior region of the wafer and a layer of PVD-deposited and/or electrodeposited copper in the edge bevel area; (b) mixing components of a liquid etchant to form the liquid etchant, wherein the components comprise an acid and an oxidizer, and wherein the mixing takes place in delivery lines provided to deliver the liquid etchant from sources of the components to the wafer; (c) generating heat by in-line mixing of the components, wherein the generated heat is used to raise the temperature of the liquid etchant to at least about 40° C.; and (d) delivering the warm liquid etchant onto the edge of the rotating wafer such that the warm liquid etchant selectively wets the edge bevel area and substantially removes unwanted copper metal selectively from the edge bevel area.