New Ch4-N-2 Dry Etch Chemistry For Poly(Methyl Methacrylate) Removal Without Consuming Polystyrene For Lamellar Copolymers Application

Directed self-assembly of block copolymers is one of the most promising solutions to reach sub-20 nm patterns. A critical challenge of this technique is the PMMA removal selectively to polystyrene (PS). A very high PMMA:PS selectivity (>10:1) is required to conserve a sufficient PS pattern thickness allowing pattern transfer to sublayers. In this paper, the authors propose a CH4-N-2 chemistry allowing a full PMMA removal without PS consumption. This chemistry is based on controlling the polymerization rate by tuning the ratio between methane and di-nitrogen. Finally, the benefits of this etch chemistry have been validated on PS-b-PMMA with a lamellar configuration. Published by the AVS.