Patent ID: 6635573
Filing Date: 2003-10-21
Classification: H01L

Abstract:
A method of etching a first material within a recess formed in a substrate of a second, different material, said method comprising the steps of:a) etching a first portion of said first material using a plasma generated from a first plasma source gas; b) detecting an endpoint for etching said first portion of said first material relative to an underlying layer of a third material which is different from said first material, wherein said endpoint is detected using thin film interferometric endpoint detection, wherein an interferometric incident light beam wavelength is tailored to said first material being etched, a spot size of a surface of said substrate illuminated by said incident light beam is sufficient to provide adequate signal intensity from said first material being etched, and a refractive index of said first material being etched is sufficiently different from a refractive index of other materials contributing to reflected light from said substrate that the combination of said light beam wavelength, said spot size, and said difference in refractive index provides a clear and distinct endpoint signal; and c) removing a remaining portion of said first material by etching using a plasma generated from a second plasma source gas, wherein said second plasma source gas provides a selectivity for etching said first material relative to said underlying layer of said third different material, where said selectivity is at least 100:1.