Volumetric Microlithography With Dual-Wavelength Depth Exposure
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Solution Overview
Problem
Current maskless 3D photolithography techniques suffer from limitations in resolution, speed, and scalability, particularly in the fabrication of high-resolution 3D structures in a planar-shaped photosensitive medium.
Innovation Solution
A method utilizing a projection system with dynamically adjustable focal length to expose a photosensitive medium to a sequence of exposure images at varying depths, combining activation and inhibition compounds responsive to different wavelengths for rapid formation of high-resolution 3D structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional photolithography techniques are used to form 2D structures with high speed, then productivity is improved, but manufacturing precision deteriorates due to diffraction limit
Solution Approach 1:
The patent transitions from 2D planar photolithography to 3D volumetric microlithography by introducing depth as a new dimension. The exposure system focuses light at different depths within the photosensitive medium to create three-dimensional structures directly, eliminating the need for sequential layer formation and achieving both high speed and high resolution in 3D space.
Solution Approach 2:
The patent replaces mechanical mask systems with a programmable spatial light modulator that dynamically patterns light in 3D space. This substitution of mechanical masks with programmable optical modulation enables flexible, high-resolution 3D structure formation without the diffraction limitations of conventional 2D mask systems.
2Device complexity
If maskless 3D photolithography techniques are used to fabricate 3D structures, then device complexity is reduced, but manufacturing precision deteriorates due to polymerization outside desired zone
Solution Approach 1:
The patent employs dual-wavelength illumination to dynamically control the polymerization process. The first wavelength initiates polymerization while the second wavelength deactivates photoinitiators in regions where polymerization should not occur. This parameter-based control (wavelength selection) enables precise 3D structure formation without the need for complex mechanical masking systems.
Solution Approach 2:
The patent introduces a photoinhibitor as an intermediary substance that responds to the second wavelength to prevent unwanted polymerization. This chemical intermediary allows the system to achieve high precision by suppressing polymerization in specific regions through optical control, maintaining both process simplicity and manufacturing precision.
3Manufacturing precision
If multiphoton photolithography is used to achieve high resolution, then manufacturing precision is improved, but productivity deteriorates due to slow fabrication speed
Solution Approach 1:
The patent uses rapid sequential projection of pre-computed exposure patterns at different focal depths to build 3D structures. By periodically updating the exposure pattern and focusing at different planes in succession, the system achieves high resolution similar to multiphoton techniques but at much higher speeds through efficient parallel processing of volumetric data.
Solution Approach 2:
The patent pre-computes exposure patterns for multiple focal planes before fabrication begins. This preliminary computation of the complete 3D exposure sequence allows the actual fabrication process to proceed rapidly by simply projecting pre-planned patterns, eliminating the need for slow real-time calculations during manufacturing while maintaining high resolution.
4Manufacturing precision
If layer-by-layer SLA fabrication is used to create 3D structures, then manufacturing precision is maintained, but productivity deteriorates significantly
Solution Approach 1:
The patent merges multiple 2D exposure operations into a single 3D volumetric exposure process. By projecting patterns at multiple focal depths simultaneously or in rapid succession within a single build step, the system combines what would traditionally require multiple sequential layer formations into one efficient operation, dramatically increasing productivity while maintaining precision through optical focusing control.
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 fast and scalable fabrication of high-resolution 3D structures with improved complexity and definition, overcoming the limitations of conventional techniques by allowing simultaneous exposure across multiple focal planes.
Implementation Method 1
The photosensitive medium comprises a photo-initiator and a monomer. The method comprises exposing the photosensitive medium to a sequence of exposure images focused at a range of depths in the photosensitive medium
Implementation Method 2
The photosensitive medium may further comprise a photo-inhibitor. The exposure images may comprise light of a first wavelength to initiate or activate the chemical reaction and/or light of a second wavelength to inhibit the chemical reaction
Data Source
AI summary
Systems and methods for volumetric microlithography are described, wherein the method may include receiving a data representation of a 3D target structure and determining a plurality of planes in a volume of a photosensitive medium or in a build volume, each plane of the plurality of planes associated with a respective depth of a plurality of depths in the build volume, the plurality of depths being defined along an optical axis of an exposure system. Each plane may correspond to a possible position of a focal plane of the exposure system. Preferably, the depths in the plurality of depths are mutually different. The photosensitive medium may include an activation compound for initiating a chemical reaction in the photosensitive medium, the activation compound being activatable by light of a first wavelength. In an embodiment, the photosensitive medium may further include an inhibition compound for inhibiting the chemical reaction in the photosensitive medium, the inhibition compound being activatable by light of a second wavelength, different from the first wavelength. The method may also comprise computing, based on a shape of the 3D target structure and, preferably, properties of the photosensitive medium, a sequence of exposure images, where each exposure image of the sequence of exposure images is associated with a plane of the plurality of planes in the build volume. Each exposure image may be associated with light of the first wavelength and/or light of the second wavelength. In an embodiment, the light may be intensity modulated light. The method may further comprise, for each focal plane of the plurality of planes, controlling the exposure system to position a focal plane of the exposure system at the depth in the build volume associated with the respective plane and to illuminate the build volume with the exposure image associated with the respective plane.