| 摘要 |
We have discovered a method of detecting the approach of an endpoint during the etching of a material within a recess such as a trench or a contact via. The method provides a clear and distinct inflection endpoint signal, even for areas of a substrate containing isolated features. The method includes etching the material in the recess and using thin film interferometric endpoint detection to detect an endpoint of the etch process, where the interferometric incident light beam wavelength is tailored to the material being etched; the spot size of the substrate illuminated by the light beam is sufficient to provide adequate signal intensity from the material being etched; and the refractive index of the material being etched is sufficiently different from the refractive index of other materials contributing to reflected light from the substrate, that the combination of the light beam wavelength, the spot size, and the difference in refractive index provides a clear and distinct endpoint signal.
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