Method and apparatus for etchback endpoint detection

Claim 1

A plasma etching system for etching titanium nitride from a semiconductor wafer in a chlorine-argon plasma, comprising: a plasma chamber for generating the chlorine-argon plasma in which electromagnetic emissions are generated; a viewport into the chamber for viewing the electromagnetic emissions; plasma control means responsive to an activation signal for initiating tracking of said etching process and to an endpoint indicator signal for terminating the etching process; detector means, coupled to the viewport, for detecting the emissions from elements present in the chamber and for generating a detector signal representing the intensity of the emissions within a limited bandwidth centered on an optical wavelength of about 700 nm; signal processor means coupled to the detector means and said control means and responsive to said activation signal for processing said limited bandwidth detector signal in response to the activation signal to generate an endpoint indicator signal which is a function of said detector signals and indication of the endpoint of said etching process, said endpoint indicator signal being coupled to said plasma control means, whereby said etching process is automatically terminated in response to said endpoint indicator signal.