Directed Self-Assembly and Pattern Transfer of Five Nanometer Block Copolymer Lamellae

Area of Science:

• Materials Science
• Nanotechnology
• Lithography

Background:

• Directed self-assembly (DSA) is crucial for nanoscale pattern fabrication.
• Block copolymers (BCPs) offer tunable properties for self-assembly.
• Achieving high resolution and density multiplication remains a challenge.

Purpose of the Study:

• To report the directed self-assembly and pattern transfer of a specific block copolymer, PVBD-b-PDSS.
• To demonstrate the formation of 5 nm features using this BCP.
• To achieve a 4x density multiplication factor through hybrid chemo-/grapho-epitaxy.

Main Methods:

• Utilized poly(5-vinyl-1,3-benzodioxole-block-pentamethyldisilylstyrene) (PVBD-b-PDSS) for lamellae formation.
• Employed nanoimprint lithography for guideline patterning to orient the BCP.
• Applied reactive ion etching for selective block removal and pattern transfer.
• Used cross-sectional scanning tunneling electron microscopy/electron energy loss spectroscopy (STEM/EELS) for analysis.

Main Results:

• Achieved well-resolved 5 nm half-pitch features in thin films.
• Demonstrated high etch selectivity for the PVBD block removal.
• Successfully transferred patterns into underlying chromium hard mask and carbon layers.
• Attained a 4x density multiplication factor via hybrid chemo-/grapho-epitaxy.

Conclusions:

• PVBD-b-PDSS is effective for high-resolution DSA and pattern transfer.
• Hybrid chemo-/grapho-epitaxy is a viable strategy for density multiplication.
• Surface treatments are necessary to control BCP orientation and prevent wetting layers.