Resist free patterning of nonpreferential buffer layers for block copolymer lithography.

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Science

Background:

• Block copolymers (BCPs) self-assemble into ordered nanostructures.
• Controlling BCP domain orientation is crucial for nanolithography and device fabrication.
• Existing methods for pattern formation can be complex and multi-step.

Purpose of the Study:

• To design a novel buffer layer for spatially controlling BCP microdomain orientation.
• To integrate bottom-up self-assembly with top-down lithography for simplified patterning.
• To achieve direct, localized control over BCP domain orientation on a substrate.

Main Methods:

• Synthesized a surface-anchored low molecular weight polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) buffer layer.
• Utilized the PMMA segment for surface anchoring and the PS block at the buffer layer/BCP interface.
• Employed electron beam (e-beam) lithography to pattern the buffer layer, acting as both a resist and a patterning agent.

Main Results:

• The buffer layer successfully induced perpendicular orientation of BCP domains.
• Tuning buffer layer composition (block lengths) created a nonpreferential surface for orientation control.
• E-beam lithography allowed for precise, localized shaving of the buffer layer, spatially defining domain orientation.
• The direct patterning approach significantly reduced the number of steps compared to conventional lithography.

Conclusions:

• A direct electron beam patternable buffer layer offers a simplified route to control BCP domain orientation.
• This approach combines self-assembly and lithography, enabling efficient spatial control of nanostructures.
• The method holds promise for advanced applications requiring precisely patterned BCP films.