Dynamic Ordering in High-χ Block Copolymer Lamellae Based on Cross-Sectional Orientational Alignment.

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Chemistry

Background:

• Next-generation block copolymer (BCP) lithography for sub-10 nm features requires understanding high-χ BCP ordering dynamics.
• Quantitative analysis of ordering and defect annihilation in thin films is challenging.
• High-χ BCPs are essential for achieving smaller feature sizes in nanolithography.

Purpose of the Study:

• To investigate the ordering dynamics and defect annihilation mechanisms of a high-χ BCP in thin films.
• To quantify the activation energy required for defect annihilation in high-χ BCPs.
• To analyze the transition in ordering regimes based on orientational order parameters.

Main Methods:

• Utilized a perpendicular lamella-forming high-χ BCP: poly(polyhedral oligomeric silsesquixone-block-2,2,2-trifluoroethyl methacrylate) (PMAPOSS-b-PTFEMA).
• Compared ordering dynamics and defect annihilation with a standard BCP, poly(styrene-block-methyl methacrylate) (PS-b-PMMA).
• Analyzed defect annihilation activation energy (Ea) and growth exponent (Φ) at different orientational order parameters (ψ2).

Main Results:

• The high-χ PMAPOSS-b-PTFEMA requires three times the activation energy (Ea = 2600 ± 420 kJ mol⁻¹) for defect annihilation compared to PS-b-PMMA.
• A transition from a fast ordering regime (Φ = 0.30) to a slow ordering regime (Φ < 0.05) was observed as orientational order increased (ψ2 > 0.36).
• Well-aligned lamellae hinder defect annihilation, necessitating enthalpically unfavorable glide mechanisms involving BCP intermixing.

Conclusions:

• High-χ BCPs exhibit distinct ordering dynamics and require significantly higher energy for defect removal.
• The observed transition in ordering regimes highlights the influence of lamellar alignment on defect dynamics.
• These findings provide critical insights for optimizing BCP lithography processes for advanced nanodevice fabrication.