Fully dry post-via-etch cleaning method for a damascene process

摘要

A method is described for cleaning freshly etched dual damascene via openings and preparing them for copper fill without damage or contamination of exposed organic or other porous low-k insulative layers. The method is entirely dry and does not expose the porous materials to contamination from moisture or solvents. The method is effective for removing all traces of residual polymer deposits from an in-process substrate wafers after via or damascene trench etching. The method employs an in-situ three-step treatment comprising a first step of exposing the electrically biased substrate wafer to a O2/N2 ashing plasma to remove photoresist and polymers, a second step immediately following the first step of remove silicon nitride etch stop layers, and a final step of treating the wafer with H2/N2 to remove copper polymer deposits formed during nitride removal. The H2/N2 plasma is capable of removing the difficult polymer residues which are otherwise only removable by wet stripping procedures. The H2/N2 plasma is not harmful to exposed porous low-k dielectric layers as well as copper metallurgy.