Exploration of non-chemically amplified resists based on dissolution inhibitors for 193 nm lithography.

摘要

Research described in this work includes exploration of new resist systems that can be used for 193 nm lithography. Most of the conventional 193 nm resists rely on chemical amplification in which a small amount of photogenerated acid can catalyze many reactions. Even though the sensitivity is improved drastically with such a mechanism, the printed profiles are known to be suffering from line edge roughness (LER) and image blurring. Furthermore, the resolution is limited by the diffusion length of the generated acid. For sub-32 nm technology nodes, specified LER criterion cannot be satisfied by utilizing chemically amplified resists (CAR). However, improvements in laser power and lens materials enable relaxation in high sensitivity requirement for the resist materials. When low sensitive photomaterials are acceptable, chemical amplification in the resists can be reduced or can even be completely eliminated. In this research, reasons behind the need of using non-chemically amplified resists is explained and some possible solutions are explored. At the end, a two component resist system that utilizes nitrobenzyl cholate as dissolution inhibitor and poly norbornene hexafluoro alcohol as the base resin is shown to achieve dense line/space patterns at 150 nm, 120 nm and 90 nm half pitches.