Orientation Control in Thin Films of a High-χ Block Copolymer with a Surface Active Embedded Neutral Layer

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Chemistry

Background:

• Directed self-assembly (DSA) of block copolymers (BCPs) is crucial for advanced integrated circuit manufacturing.
• Current BCPs like PS-b-PMMA have limited patterning resolution due to weak Flory interaction parameters (χ).
• High-χ BCPs offer smaller feature sizes but struggle with perpendicular orientation due to surface energy imbalances.

Purpose of the Study:

• To develop a novel approach to enable the use of high-χ BCPs for sub-10 nm feature patterning.
• To overcome the challenge of achieving perpendicular orientation in high-χ BCP thin films.
• To introduce an additive that balances surface tensions at the film's air interface.

Main Methods:

• A polymeric surface active additive, an embedded neutral layer (ENL), was designed and mixed into BCP solutions.
• The ENL comprises a second BCP with a neutral block and a surface anchoring block.
• The ENL segregates to the top of the BCP film during casting and annealing, balancing surface tensions.

Main Results:

• The ENL additive successfully balanced surface tensions at the top of the BCP thin film.
• Perpendicular orientation of microdomains was achieved, enabling smaller feature sizes.
• DSA was demonstrated using the ENL formulation on a chemical patterned template with a single coat and thermal annealing.

Conclusions:

• The embedded neutral layer (ENL) technology effectively enables the use of high-χ BCPs for advanced patterning.
• This approach addresses surface energy imbalances, facilitating sub-10 nm feature creation.
• ENL technology shows significant promise for future integrated circuit manufacturing.