All-Wet Strip Approaches for Post-Etch Photoresist Layers After Low-K Patterning

Abstract

Wet-only removal of post-etch (meth-)acrylate based photoresist on porous low-k dielectrics applied in either resist or metal hard mask based patterning is investigated. Characterization of photoresist degradation by etch is applied to support the selection of wet cleaning chemistries and/or cleaning processes. FTIR and 1H-NMR analysis results indicate a common degradation mechanism for both patterning schemes with formation of double carbon bonds in a cross-linked crust that is insoluble in organic solvents. Even though a common degradation method is observed, resist cleanability in metal hard mask applications is by far more difficult due to a higher degree of resist cross-linking. Cleaning approaches by dissolution in solvents in combination with physical forces, for both patterning schemes, are discussed in detail.