Abstract: A method of etching a substrate includes placing a substrate in a process zone. The substrate has a material with a thickness, and the material has exposed regions between features of a patterned mask. An etchant gas is introduced into the process zone. The etchant gas is energized to etch the material. An endpoint of etching the material of the substrate is determined by (i) reflecting a light beam from the substrate, the light beam having a wavelength selected to have a coherence length in the substrate of from about 1.5 to about 4 times the thickness of the material, and (ii) detecting the reflected light beam to determine an endpoint of the substrate etching process. Additionally, the wavelength of the light beam can be selected to maximize an absorption differential that is a difference between the absorption of the light beam in the patterned mask and the absorption of the light beam in the material.

Abstract: A substrate is etched in a process zone by placing the substrate in the process zone, providing an energized process gas in the process zone, and exhausting the process gas. A first stage of the etching process is monitored to determine completion of the first stage by detecting the intensities of one or more wavelengths of a radiation emission generated by the energized gas, generating a first signal in relation to the detected intensities, and evaluating the first signal. A second stage of the etching process is monitored to determine completion of the second stage by detecting the intensities of one or more wavelengths of a polarized radiation reflected from the substrate being etched, generating a second signal in relation to the detected intensities, and evaluating the second signal.

Abstract: A substrate is etched in a process zone by placing the substrate in the process zone, providing an energized process gas in the process zone, and exhausting the process gas. A first stage of the etching process is monitored to determine completion of the first stage by detecting the intensities of one or more wavelengths of a radiation emission generated by the energized gas, generating a first signal in relation to the detected intensities, and evaluating the first signal. A second stage of the etching process is monitored to determine completion of the second stage by detecting the intensities of one or more wavelengths of a polarized radiation reflected from the substrate being etched, generating a second signal in relation to the detected intensities, and evaluating the second signal.