Enhanced etching resolution of self-assembled PS-b-PMMA block copolymer films by ionic liquid additives

Area of Science:

• Materials Science
• Polymer Chemistry

Background:

• Polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) is a widely studied block copolymer for self-assembly.
• Insufficient etching resolution poses challenges for pattern transfer of PS-b-PMMA block copolymers (BCPs).

Purpose of the Study:

• To investigate the effect of ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate (HMHF) additives on the line edge roughness (LER) of PS-b-PMMA self-assembled patterns.
• To explore a novel strategy for improving the performance of block copolymers in microelectronics fabrication.

Main Methods:

• Studied the impact of HMHF additives on PS-b-PMMA films.
• Analyzed changes in the Flory-Huggins interaction parameter (χ) and phase separation behavior.
• Evaluated LER performance with HMHF blended directly or in a top layer.

Main Results:

• Trace HMHF addition maintained photolithography compatibility.
• HMHF significantly increased the Flory-Huggins interaction parameter (χ) and promoted phase separation.
• LER was effectively decreased by blending HMHF with PS-b-PMMA or via a polyvinylpyrrolidone top layer.

Conclusions:

• Ionic liquid additives offer an effective strategy to enhance the self-assembly and pattern quality of PS-b-PMMA block copolymers.
• This method addresses the limitations of existing block copolymers for high-resolution pattern transfer.