interferometer endpoint detection method in the substrate etch process

摘要

method for etching a substrate includes placing a substrate in the process zone (zone). The substrate has a material with a thickness, the material has a region exposed between the parts (features) of the patterned mask. The etchant gas is supplied to the processing zone. The etchant gas is enabled etching the material. Etching end point of the substrate material is selected from: (i) reflects a light beam having a wavelength selected so as to have a 1.5 times to about 4 times the coherence length of the material thickness within the substrate from the substrate, (ii) the substrate to detect a reflected light beam By determining the end point is determined in the etching process. In addition, the wavelength of the light beam absorption difference (absorption differential), that is, can be selected to maximize the difference between the absorption of the light beam with the substance in the absorption of the light beam from the patterned mask.