Nanoperforated Graphene Fabrication via Block Copolymer Lithography
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Solution Overview
Problem
Graphene's limited band gap and the challenges of nanopatterning techniques, such as electron-beam lithography, which struggle with achieving sub-20 nm resolution and scalability for large-area patterning, hinder its practical application in electronic devices.
Innovation Solution
The development of nanoperforated graphene materials using block copolymer lithography, which involves forming an etch mask with a wetting layer, neutral layer, and pattern-defining copolymer layer to create periodic arrays of holes with dimensions less than 20 nm, enabling scalable and high-fidelity patterning of graphene for large-area applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electron-beam lithography is used to pattern graphene nanostructures, then sub-20 nm resolution can be achieved, but throughput is limited and scalability to large-area patterning is restricted
Solution Approach 1:
The patent divides the patterning process into multiple layers: a wetting layer for adhesion, a neutral layer (block copolymer) for self-assembly, and a pattern-defining layer for final pattern formation. This segmentation allows each layer to perform its specific function optimally, enabling high-resolution patterning across large areas through parallel processing
Solution Approach 2:
The neutral layer acts as an intermediary between the wetting layer and the pattern-defining layer. It provides a platform for block copolymer self-assembly while maintaining adhesion to the substrate and allowing precise pattern transfer, thus bridging the gap between adhesion requirements and patterning precision
2Reliability
If graphene is used for electronic applications, then excellent charge transport characteristics are achieved, but the lack of a technologically significant band gap limits conductance modulation
Solution Approach 1:
The patent applies quantum confinement effects by confining charge carriers to narrow nanoribbon channels (width w) within the graphene sheet. This local confinement creates a band gap Eg that scales inversely with width (Eg ∝ 1/w), allowing the material to maintain excellent charge transport in the channel direction while gaining semiconducting behavior through spatial confinement
Solution Approach 2:
The patent changes the physical parameters of graphene by patterning it into nanoribbons with controlled widths. This geometric parameter change (from 2D sheet to 1D nanoribbons) fundamentally alters the electronic structure, opening a band gap that enables field-effect modulation while preserving the high mobility characteristics of graphene
3Manufacturing precision
If nanoperforated graphene is fabricated with features less than 20 nm, then a semiconducting band gap of at least 100 meV is achieved, but the fabrication complexity increases
Solution Approach 1:
The patent performs preliminary self-assembly of block copolymers into ordered domains before final pattern transfer. This preliminary organization of material into precise nanoscale patterns simplifies subsequent etching steps and reduces the complexity of achieving sub-20 nm features, as the self-assembly process naturally provides the required precision
Solution Approach 2:
The block copolymer system performs self-service by automatically organizing into ordered domains through self-assembly, eliminating the need for complex external alignment and patterning tools. The system self-organizes to create the precise sub-20 nm features required for semiconducting behavior, reducing fabrication complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for the fabrication of nanoperforated graphene with features less than 10 nm, providing a semiconducting material with a band gap of at least 100 meV, enhancing conductance modulation and enabling practical applications in electronics and optoelectronics.
Implementation Method 1
exposing the deposited pattern-forming block copolymer to a vapor atmosphere saturated with an annealing solvent for a time sufficient to allow the pattern-forming block copolymer to self assemble into oriented domains
Implementation Method 2
allow the pattern-forming block copolymer to self assemble into oriented domains
Implementation Method 3
patterning the array of holes into the graphene material
Implementation Method 4
it has been shown that quantum confinement effects can be used to open up a band gap in graphene
Data Source
AI summary
Methods for forming a nanoperforated graphene material are provided. The methods comprise forming an etch mask defining a periodic array of holes over a graphene material and patterning the periodic array of holes into the graphene material. The etch mask comprises a pattern-defining block copolymer layer, and can optionally also comprise a wetting layer and a neutral layer. The nanoperforated graphene material can consist of a single sheet of graphene or a plurality of graphene sheets.