Method and apparatus for contactless real-time in-situ monitoring of a chemical etching process

摘要

A contactless method and apparatus for in-situ chemical etch monitoring of an etching process during etching of a workpiece (16), e.g. a silicon wafer with a wet chemical etchant (18) are disclosed. The method comprises steps of providing at least two toroidal windings (12) in the wet chemical etchant to be proximate to but not in contact with the workpiece; and monitoring an electrical characteristic , e.g. the impedance of wafer between said at least two toroidal windings, wherein a prescribed change in the electrical characteristic is indicative of a prescribed condition of the etching process, e.g. the etch rate. Such a method and apparatus are particularly useful in a wet chemical etch station.