An Acid-Cleavable Lamellar Block Copolymer for Sub-30-nm Line Spacing Patterning via Graphoepitaxial Directed...

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Chemistry

Background:

• Graphoepitaxial directed self-assembly (DSA) of block copolymers (BCPs) is crucial for sub-30 nm patterning in semiconductor nanofabrication.
• Polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) is widely used but faces challenges in pattern fidelity due to limited etch contrast and reliance on UV for PMMA removal.

Purpose of the Study:

• To synthesize and characterize a novel acid-cleavable lamellar BCP, PS-N=CH-PMMA, with a dynamic Schiff base linkage.
• To evaluate its potential for UV-free wet etching and improved nanopatterning fidelity compared to traditional PS-b-PMMA.

Main Methods:

• Synthesis of PS-N=CH-PMMA with a dynamic Schiff base linkage.
• Directed self-assembly within 193i-defined trench templates.
• UV-free wet etching using glacial acetic acid.
• Characterization using SEM, FIB-TEM, and Ohta-Kawasaki simulations.

Main Results:

• PS-N=CH-PMMA self-assembles into vertically aligned lamellar nanostructures with tunable domain spacing (36.1–40.2 nm).
• Achieved well-ordered one-space-per-trench patterns with tunable interline spacings (15–25 nm) in 55 nm templates, demonstrating significant line spacing shrinkage.
• Exhibited improved vertical etch profiles and reduced PMMA residue compared to PS-b-PMMA, without UV exposure.
• Ohta-Kawasaki simulations indicated trench sidewall angle critically influences PS distribution and residual morphology.

Conclusions:

• Dynamic covalent chemistry, specifically the Schiff base linkage, enhances wet development fidelity in BCP lithography.
• PS-N=CH-PMMA offers a thermally compatible, UV-free strategy for sub-30 nm nanopatterning with improved etch performance.
• This approach holds significant potential for advanced semiconductor nanofabrication processes.