Patent ID: 8900469

Claim:
A method of determining an etching endpoint of a tantalum containing layer disposed on a substrate during an etching process, comprising: performing an etching process on a first tantalum containing layer disposed on a second tantalum containing layer disposed on a first surface of a substrate through a patterned mask layer in a plasma etch chamber; directing radiation having a first wavelength from between about 200 nm and about 800 nm to an area of the first tantalum containing layer uncovered by the patterned mask layer during the etching process; collecting an optical signal reflected from the area uncovered by the patterned mask layer; analyzing a waveform obtained from the reflected optical signal; and determining a first endpoint of the etching process when a slope of the waveform changes by about 5 percent or greater; and continuing collecting the optical signal reflected from the area uncovered by the patterned mask layer after the first endpoint of the etching process is determined.