a process for removal of residual silicon oxide hardmask used to etch vias in low - k organic polymer dielectric layers is described . the hardmask deteriorates by developing an angular aspect or faceting along the pattern edges when used to etch organic polymer layers in an oxygen / inert gas plasma in a high density plasma etcher . in addition the deterioration of the hardmask during organic polymer etching causes a significant degradation of surface planarity which would result in via - to - via shorts when a second metal layer is patterned over it if the hardmask were left in place . the residual hardmask is selectively removed immediately after the via etch by a soft plasma etch which restores surface planarity and removes via edge facets . the plasma etch has a high selectivity of oxide - to - organic polymer so that the surface irregularities are not transferred to the polymer surface and the exposed metal surface at the base of the via is also unscathed .