Development of Ordered, Porous (Sub-25 nm Dimensions) Surface Membrane Structures Using a Block Copolymer Approach

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Chemistry

Background:

• Block copolymer (BCP) lithography is crucial for creating nanoscale patterns.
• Developing high-aspect-ratio vertical pore arrangements requires advanced lithographic techniques.

Purpose of the Study:

• To develop a block copolymer lithography method for generating high-aspect vertical pore arrangements.
• To create uniform, arranged, sub-25 nm cylindrical nanopore arrays in a substrate surface.

Main Methods:

• Utilized a microphase-separated poly(ethylene oxide)-block-polystyrene (PEO-b-PS) thin film with polystyrene as the cylinder-forming phase.
• Incorporated hard mask material into the matrix block to amplify etch contrast.
• Applied selective metal ion inclusion into the PEO matrix followed by etch/modification to create iron oxide nanohole arrays.
• Used the iron oxide nanohole network as a resistant mask for pattern transfer into silicon.

Main Results:

• Generated uniform, arranged, sub-25 nm cylindrical nanopore arrays.
• Created cylindrical iron oxide nanoholes (22 nm diameter) mimicking BCP nanopatterns.
• Fabricated ultra-dense, well-ordered silicon nanopore arrays with good sidewall profiles and controllable depth.

Conclusions:

• The developed method enables precise fabrication of ordered nanopore arrays.
• This technique offers a robust pattern transfer approach for creating high-quality silicon nanopores.
• The process allows for control over the depth of the porous structure.