De-fluorination of wafer surface and related structure
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Methods of de-fluorinating a wafer surface after damascene processing and prior to photoresist removal are disclosed, as is a related structure. In one embodiment, the method places the wafer surface in a chamber and exposes the wafer surface to a plasma from a source gas including at least one of nitrogen (N2) and/or hydrogen (H2) at a low power density or ion density. The exposing step removes the chemisorbed and physisorbed fluorine residue present on the wafer surface (and chamber), and improves ultra low dielectric (ULK) interconnect structure robustness and integrity. The exposing step is operative due to the efficacy of hydrogen and nitrogen radicals at removing fluorine-based species and also due to the presence of a minimal amount of ion energy in the plasma. The low power density nitrogen and/or hydrogen-containing plasma process enables negligible ash/adhesion promoter interaction and reduces integration complexity during dual damascene processing of low-k OSG-based materials.