Perpendicular Block Copolymer Microdomains in High Aspect Ratio Templates

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• Controlling the orientation of block copolymer microdomains is crucial for nanotechnology applications.
• High aspect ratio nanostructures present unique challenges for achieving desired domain alignment.

Purpose of the Study:

• To achieve perpendicular orientation of lamellar microdomains in a high interaction parameter block copolymer within high aspect ratio gratings.
• To develop guidelines for controlling nanostructure orientation in confined geometries.

Main Methods:

• Utilized polystyrene-block-polydimethylsiloxane (PS-b-PDMS) block copolymers in interference lithography-defined trenches.
• Employed both thermal and solvent annealing with various solvent vapors.
• Incorporated a platinum (Pt) layer to prevent wetting layer formation.
• Interpreted results using self-consistent field theory (SCFT) simulations and a Ginzburg-Landau (GL) analytic model.

Main Results:

• Successfully obtained perpendicular orientation of lamellar microdomains in PS-b-PDMS within high aspect ratio gratings.
• Demonstrated that perpendicular alignment is achievable across various film thicknesses, trench widths, and annealing conditions.
• Validated experimental findings with SCFT and GL modeling, which accurately predicted domain orientation based on surface energies and aspect ratio.

Conclusions:

• Functionalized high aspect ratio gratings with preferential sidewall brushes enable perpendicular orientation of block copolymer lamellar microdomains.
• The study provides a predictive model and practical guidelines for directing nanostructure self-assembly within topographic features.
• This work advances the precise fabrication of ordered nanostructures for advanced material applications.