Multi-Layer Photoresist Structuring for Stepped 3D Microstructures
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Solution Overview
Problem
Current methods for producing microstructures in the micrometer and submicrometer range using photoresist lack the capability to efficiently create stepped or overhanging structures with larger ablation depths without significant increases in energy or time investment.
Innovation Solution
A process involving a metal-clad substrate coated with multiple photoresists of differing sensitivities and transmission characteristics, exposed to specific wavelength ranges and doses to generate multi-layer photoresist structures, allowing for the creation of complex three-dimensional structures with defined height and shape, followed by metal deposition and etching to form metallic microstructures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single photoresist layer is used for photolithographic patterning, then the process is simple and fast, but the ablation depth is limited to approximately 0.1 μm and cannot produce structures with larger depths or overhanging geometries
Solution Approach 1:
The photoresist system is segmented into multiple layers with different photosensitivities. Each layer can be exposed and developed independently to create structures at different depth levels, enabling ablation depths far exceeding 0.1 μm while maintaining process control
Solution Approach 2:
The invention transitions from a single-layer two-dimensional patterning approach to a multi-layer three-dimensional structure formation process. By stacking photoresist layers with different photosensitivities and exposing them sequentially, complex 3D geometries including overhanging structures can be created
2Manufacturing precision
If multiple photoresist layers with different photosensitivities are used to increase ablation depth, then structures with defined height steps and overhanging geometries can be produced, but the process complexity and number of process steps increase
Solution Approach 1:
Multiple photoresist layers are coated and prepared in advance before exposure. The different photosensitivity layers are pre-positioned to respond to specific wavelengths, allowing subsequent exposure processes to selectively activate each layer without requiring re-coating steps
Solution Approach 2:
The multi-layer photoresist system serves multiple functions simultaneously: it defines horizontal patterning boundaries at different heights, creates overhanging geometries, and enables selective ablation at different depth levels, all within a single integrated structure
3Manufacturing precision
If conventional photolithography is used for micrometer and submicrometer structures, then the process is well-established, but it cannot efficiently produce stepped or overhanging structures with larger ablation depths without significant increases in energy or time investment
Solution Approach 1:
The invention changes the photosensitivity parameter across multiple layers by using photoresists with different spectral responses. This allows selective exposure at different wavelengths, enabling precise control over which layers are activated at each exposure step without requiring excessive energy or time
Solution Approach 2:
The invention replaces mechanical or sequential layer-by-layer fabrication approaches with an optical differentiation system. By using photoresists with different photosensitivities that respond to specific wavelengths, the system optically distinguishes between layers and controls their exposure independently, eliminating the need for repeated mechanical processing steps
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 flexible and high-throughput production of microelectronic and micromechanical structures with precise control over structure configuration, achieving ablation depths in the micrometer to millimeter range while maintaining edge quality and reducing production time and energy costs.
Implementation Method 1
exposing (4) the first photoresist with an exposure radiation (41) with a first wavelength range and a first radiation dose in at least one structure-forming region (35) of the first photoresist; exposing at least the second photoresist with exposure radiation (42) with a second wavelength range and a second radiation dose in at least one structure-forming region (36) of the second photoresist
Implementation Method 2
developing (5) at least one multi-layer photoresist structure (6) from the overlapping structure-forming regions (35; 36; 37) at least of the first photoresist and second photoresist by developing the non-structure-forming exposed regions of the coatings (31; 32; 33; 34) of at least the first photoresist and second photoresist
Data Source
AI summary
A process for the production of three-dimensional structures involves generating stepped structures in the micrometer to millimeter range. A novel possibility for realizing microstructures for micromechanical and high-performance electronic structures allows a substantially free shaping of and high-throughput production of stepped structures is met according to the invention by coating a copper-clad substrate at least once with a first photoresist for generating a defined height of at least one structure step and coating the first photoresist at least once with a second photoresist for generating a defined height of at least one further structure step, wherein the first photoresist and the second photoresist have different photosensitivities and transmission characteristics which generate structure-forming regions at least of the first photoresist and second photoresist by exposing with different wavelengths and radiation doses and after developing. The structure-forming regions at least partially overlap one another and form a stepped three-dimensional structure.