EUV Double Patterning Solution for Subtractive Metal Patterning at 18nm Pitch

Abstract

In this work, we demonstrate a self-aligned litho-etch litho-etch (SALELE) process flow for 18nm pitch patterning of subtractive Ru structures. This process combines many individual steps from a standard damascene double patterning flow with a spacer pull process to adapt it for subtractive patterning. Requiring two EUV exposures, this process flow enables a broad design space comparable to existing SALELE solutions for damascene integrations. Utilizing this process flow, we have demonstrated successful patterning of complex designs including intertwined comb-serpentines and various mixed pitch patterns. We report matched resistance for both mandrel and non-mandrel resistors. Additionally, we demonstrate equivalent yields for 1mm long intertwined comb-serpentine structures with serpentines formed from both mandrel and non-mandrel patterns.