Etch rate detection for anti-reflective coating layer and absorber layer etching

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 tantalum and oxygen containing layer disposed on a first surface of a substrate through a patterned mask layer in a plasma etch chamber;
• directing a first radiation source having a first wavelength from about 200 nm and about 800 nm from the first surface of the substrate to an area uncovered by the patterned mask layer;
• collecting a first optical signal reflected from the area covered by the patterned mask layer to obtain a first waveform from the reflected first optical signal;
• analyzing a first waveform obtained the reflected first optical signal reflected from the first surface of the substrate from a first time point to a second time point;
• determining a first endpoint of the etching process when a slope of the waveform is changed about 5 percent or greater from the first time point to the second time point;
• continuing etching a tantalum containing and oxygen free layer disposed between the tantalum containing and oxygen free layer and substrate;
• directing a second radiation source having a second wavelength from about 200 nm and about 800 nm from the first surface of the substrate to an area uncovered by the patterned mask layer and the etched tantalum containing and oxygen free layer;
• collecting a second optical signal reflected from the area covered by the patterned mask layer and the etched tantalum and oxygen containing layer to obtain a second waveform from the reflected second optical signal;
• analyzing a second waveform obtained the reflected second optical signal reflected from the first surface of the substrate from a third time point to a fourth time point;
• and
• determining a second endpoint of the etching process when a slope of the waveform is changed about 5 percent or greater from the third time point to the fourth time point.

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 tantalum and oxygen containing layer disposed on a first surface of a substrate through a patterned mask layer in a plasma etch chamber;
• directing a first radiation source having a first wavelength from about 220 nm from the first surface of the substrate to an area uncovered by the patterned mask layer;
• collecting a first optical signal reflected from the area covered by the patterned mask layer to obtain a first waveform from the reflected first optical signal;
• analyzing a first waveform obtained the reflected first optical signal reflected from the first surface of the substrate;
• determining a first endpoint of the etching process when the reflected first optical signal becomes saturated;
• continuing etching a tantalum containing and oxygen free layer disposed between the tantalum containing and oxygen free layer and substrate;
• directing a second radiation source having a second wavelength about 230 nm from the first surface of the substrate to an area uncovered by the patterned mask layer and the etched tantalum containing and oxygen free layer;
• collecting a second optical signal reflected from the area covered by the patterned mask layer and the etched tantalum and oxygen containing layer to obtain a second waveform from the reflected second optical signal;
• analyzing a second waveform obtained the reflected second optical signal reflected from the first surface of the substrate;
• and
• determining a second endpoint of the etching process when the reflected second optical signal becomes saturated.