Patent ID: 8808559

Claim:
A method of determining an etching endpoint of a reflective multi-material layer disposed on a substrate during an etching process, comprising: performing an etching process on a reflective multi-material layer, wherein the reflective multi-material layer includes at least one molybdenum layer and one silicon layer disposed on a first surface of a substrate through a patterned mask layer in a plasma etch chamber; directing radiation having a wavelength from about 170 nm and about 800 nm to an area of the multi-material 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 an intensity of the reflected optical signal is between about 60 percent and about 90 percent less than an initial reflected optical signal.