Nanoparticle Assembly Etch Masks for Sub-20nm Patterning
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Solution Overview
Problem
Current techniques for generating two-dimensional dense assemblies or periodic arrays with feature sizes of 20 nm or smaller are challenging due to limitations in electron beam lithography and block copolymer lithography, such as slow patterning times, difficulty in achieving high packing densities, and stringent energetic requirements for surface and interface control.
Innovation Solution
Self-assembled nanoparticle assemblies are used as etch masks to fabricate large area, high-density two-dimensional periodic arrays with feature sizes less than 20 nm, involving the deposition of surfactant-coated nanoparticles, stabilization with electron beam treatment, selective removal of surfactants, and reactive ion etching to transfer patterns into substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electron beam lithography is used to fabricate nanoscale features, then individual nanoscale features can be fabricated on a resist, but patterning a single magnetic hard disk may require about a week and achieving feature sizes less than 20 nm may be challenging due to forward scattering of electrons
Solution Approach 1:
The patent employs self-assembled monolayers of nanoparticles that automatically organize into periodic arrays on the substrate. The nanoparticles serve as their own positioning mechanism through self-assembly driven by surface energy minimization, eliminating the need for time-consuming electron beam writing of each feature individually. This self-organizing process enables parallel formation of multiple features simultaneously.
Solution Approach 2:
The nanoparticle assemblies act as physical templates or masks that copy their periodic arrangement pattern onto the underlying substrate through subsequent etching processes. The self-assembled nanoparticle pattern is transferred to the substrate, creating identical periodic features without requiring direct writing of each feature.
2Manufacturing precision
If electron beam lithography is used to achieve high packing densities, then individual nanoscale features can be fabricated, but attaining high packing densities may also be difficult due to forward scattering of electrons
Solution Approach 1:
The patent introduces nanoparticles as an intermediary layer between the resist and substrate. These nanoparticles self-assemble into periodic arrays with controlled spacing, serving as a physical template that defines the final pattern. The nanoparticle assembly acts as a mask during etching, transferring the periodic pattern to the substrate with high packing density that overcomes electron scattering limitations.
3Manufacturing precision
If block copolymers are used for self-assembly, then polymer domains can be combined with conventional lithography to make patterned arrays, but there are stringent requirements on the energetics of surface and interface to control the morphologies, making it increasingly difficult to scale to sizes below 20 nm
Solution Approach 1:
The patent uses inorganic nanoparticles as temporary sacrificial masks that are removed after pattern transfer. These nanoparticles serve their purpose during the etching process and are then eliminated, leaving behind the desired periodic pattern in the substrate. This disposable approach simplifies the overall process compared to maintaining complex block copolymer morphologies throughout.
4Productivity
If conventional lithography is combined with block copolymer self-assembly to make patterned arrays, then two-dimensional dense assemblies can be generated, but the stringent requirements on surface and interface energetics make it increasingly difficult to scale to sizes below 20 nm
Solution Approach 1:
The patent changes the fundamental parameter from polymer-based self-assembly to inorganic nanoparticle self-assembly. Inorganic nanoparticles offer different physical and chemical properties that enable better control over assembly morphology and stability. This parameter change allows scaling to smaller feature sizes below 20 nm while maintaining processability and reducing surface energy control requirements.
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 enables rapid, reliable, and cost-effective fabrication of patterned assemblies like dot and antidot arrays with higher densities than traditional methods, achieving feature sizes as small as 1 nm and maintaining pattern integrity.
Implementation Method 1
depositing, onto the at least one layer in which the patterned dot array is to be fabricated, a nanoparticle layer, wherein the nanoparticle layer comprises one or more surfactants and nanoparticles coated with the one or more surfactants
Implementation Method 2
Self-assembled nanoparticle assemblies are used as etch masks to fabricate large area, high-density two-dimensional periodic arrays
Implementation Method 3
treating the one or more surfactants that coat the nanoparticles and the portions of the one or more surfactants that fill the spaces among the nanoparticles comprises: irradiating the one or more surfactants using an electron beam to convert the one or more surfactant into hydrogenated amorphous carbon
Implementation Method 4
removing, from the nanoparticle layer, the portions of the one or more surfactants that fill the spaces among the nanoparticles to expose portions of the at least one layer in which the patterned dot array is to be fabricated
Implementation Method 5
etching the exposed portions of the at least one layer in which the patterned dot array is to be fabricated
Data Source
AI summary
In one aspect, a method comprises: providing a substrate having at least one layer in which the patterned dot array is to be fabricated; depositing a nanoparticle layer, wherein the nanoparticle layer comprises one or more surfactants and nanoparticles coated with the one or more surfactants; treating the one or more surfactants that coat the nanoparticles and the portions of the one or more surfactants that fill the spaces among the nanoparticles; removing the portions of the one or more surfactants that fill the spaces among the nanoparticles to expose portions of the at least one layer in which the patterned dot array is to be fabricated; etching the exposed portions of the at least one layer in which the patterned dot array is to be fabricated; and removing at least a portion of the nanoparticles.