SiARC Residue Reduction Methods with Minimizing Profile Change for Mask Patterning

Tri-layer mask scheme including photoresist (PR), Si-based anti-reflection coating (SiARC) and spin-on carbon (SOC) is applied to transfer PR pattern and shrink the critical dimension (CD) to the underneath patterning layer (PL). However, due to the presence of different pitches, SiARC residues were often observed on the remained pattering layer after the etch and the wet clean, especially on the patterns with the larger pitches. However, the trade-offs between the SiARC residue removal efficiency and the profile control bring big challenges for finding proper solution that only fully removes the residues but minimizes profile change. In this study, the reason for the formation of SiARC residues is illustrated. Moreover, we show how to balance these trade-offs to eliminate the SiARC residues but also to minimize the profile changes.