Orthogonally Aligned Block Copolymer Line Patterns on Minimal Topographic Patterns.

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Chemistry

Background:

• Block copolymers (BCP) self-assemble into ordered nanostructures.
• Controlling the orientation of BCP microdomains is crucial for nanomanufacturing applications.
• Existing methods often struggle with large-area, precise orientation control.

Purpose of the Study:

• To demonstrate the generation of orthogonally aligned BCP line patterns over large areas.
• To investigate the role of film thickness and solvent-induced capillary flow in BCP alignment.
• To establish a scalable method for fabricating hierarchical nanostructures.

Main Methods:

• Solvent-vapor annealing of BCP films on topographically patterned substrates.
• Systematic variation of BCP film thickness.
• Grazing incidence small-angle X-ray scattering (GISAXS) for orientation analysis.

Main Results:

• Orthogonal alignment of BCP cylindrical microdomains was achieved relative to trench patterns.
• Optimal orthogonal alignment occurred at a film thickness of 1.70 L₀.
• Capillary flow of solvent across trenches was identified as a key alignment factor.
• GISAXS confirmed nearly perfect orientation with an orientation function of 0.997.

Conclusions:

• Solvent-vapor annealing provides a scalable route to orthogonally aligned BCP patterns.
• This technique enables precise control over BCP microdomain orientation on nanostructures.
• The method is promising for the fabrication of complex, hierarchical nanostructures for advanced applications.