Self-Aligned Sub-Wavelength Lithography via Surface Plasmon Coupling
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Solution Overview
Problem
Standard photolithographic methods are limited to feature sizes around the wavelength of light, making it impossible to create designs smaller than a few hundred nanometers, and alternative methods like electron beam lithography are slow and costly.
Innovation Solution
A method and apparatus for self-aligned, sub-wavelength optical lithography using a region of photoresist above a conductive surface with periodically arrayed openings, where low-intensity light is used to couple with surface plasmons, enhancing the energy at specific locations to cure the photoresist, allowing for feature sizes significantly smaller than the openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If standard photolithographic methods are used, then the process is simple and fast, but the feature size is limited to approximately the wavelength of light
Solution Approach 1:
The conductive surface is segmented into periodically arrayed openings that act as independent plasmon coupling elements. Each opening functions as a discrete unit for generating surface plasmons, enabling precise spatial control of energy distribution and achieving sub-wavelength feature sizes through the collective effect of multiple segmented elements
Solution Approach 2:
Surface plasmons serve as an intermediary mechanism between the incident light and the photoresist. The periodically arrayed openings on the conductive surface mediate the coupling of light energy to surface plasmons, which then concentrate energy at sub-wavelength locations to cure the photoresist, bridging the gap between optical lithography and nanoscale patterning
2Manufacturing precision
If electron beam lithography is used to achieve smaller features, then the feature size can be reduced to tens of nanometers, but the process becomes extremely slow and costly
Solution Approach 1:
The periodically arrayed openings on the conductive surface create a regular spatial pattern that enables systematic and efficient energy distribution. This periodic structure allows parallel processing of multiple features simultaneously, maintaining high productivity while achieving the sub-wavelength precision normally requiring slow serial electron beam writing
Solution Approach 2:
The invention replaces the mechanical scanning process of electron beam lithography with an optical field-based approach. Instead of physically moving an electron beam across the surface serially, the system uses light fields coupled to surface plasmons to simultaneously address multiple locations, achieving electron-beam-level precision with photolithography-speed productivity
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
Enables the creation of sub-wavelength features using standard optical lithography without the need for expensive alignment, achieving feature sizes of tens of nanometers with increased energy levels at designated locations, improving efficiency and reducing costs.
Implementation Method 1
the provided light energy is less intense than the amount of light energy required to cure the photoresist. However, the effect of the pattern on the conductive plate is to couple the provided light within some range of wavelength and/or incidence angles to surface excitations of the metal surface called surface plasmons
Data Source
AI summary
Embodiments of the invention provide a method and an apparatus for performing self-aligned, sub-wavelength optical lithography. One embodiment provides a region of photoresist above a conductive surface having a plurality of periodically arrayed openings extending therethrough. At least a portion of the region of photoresist is then exposed to a light, wherein the intensity of the light is less than the intensity required to cure the photoresist. In so doing, at least one self-aligned, sub-wavelength location in at least one location of the region of photoresist is cured.