Carbohydrate-based block copolymer systems: directed self-assembly for nanolithography applications.

Area of Science:

• Nanoscience and Nanotechnology
• Materials Science
• Polymer Chemistry

Background:

• Block copolymers (BCPs) offer a promising route for nanolithography, particularly for creating structures below 10 nm.
• Directed self-assembly (DSA) and pattern transfer are critical challenges for BCPs at these small scales.

Purpose of the Study:

• To demonstrate directed self-assembly (DSA) of a maltoheptaose-block-polystyrene (MH-b-PS) BCP system using graphoepitaxy for sub-10 nm nanolithography.
• To investigate the self-organization behavior and pattern transfer capabilities of the MH-b-PS BCP.

Main Methods:

• Utilized graphoepitaxy with guiding patterns created by electron beam lithography (EBL) and lift-off.
• Employed solvent vapor annealing in tetrahydrofuran (THF) and water for BCP self-organization.
• Analyzed BCP patterns using Atomic Force Microscopy (AFM) and evaluated etch selectivity using Reactive Ion Etching (RIE).

Main Results:

• Achieved sub-10 nm scale cylinder formation of the maltoheptaose (MH) block within a polystyrene (PS) matrix.
• Demonstrated good ordering of vertical and horizontal cylindrical MH arrays via DSA for guiding patterns with 150-200 nm separation.
• Observed a significantly higher etch rate for MH (up to 14x) compared to PS using O2 and CF4 plasma in RIE.

Conclusions:

• The maltoheptaose-block-polystyrene (MH-b-PS) BCP system shows significant potential for nanolithographic applications below 10 nm.
• Successful DSA and differential etch rates are key for fabricating high-resolution nanostructures.