Iterative Exposure Compensation for 3D Resist Topography
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Solution Overview
Problem
Existing methods for creating three-dimensional topographic structures in positive-tone photoresists face challenges in achieving accurate depth and shape control due to non-linear effects, such as bleaching and absorption, which result in sensitivity to disturbances like laser noise and resist property variations, leading to inconsistent results.
Innovation Solution
The method involves iterative exposure dose refinement using a rule-based or model-based compensation approach that adjusts gray-scale values and focal planes to account for non-linear effects, bleaching, and absorption, ensuring precise control over the exposure process to achieve accurate three-dimensional latent images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional exposure methods are used to create three-dimensional topographic structures in positive-tone photoresist, then the process is simple and straightforward, but the depth and shape control accuracy deteriorates due to non-linear effects like bleaching and absorption
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-compensating for non-linear effects through iterative exposure dose refinement. Before the actual exposure, the system simulates the exposure process multiple times, adjusting gray-scale values and focal planes to account for anticipated bleaching and absorption effects, thereby achieving accurate depth and shape control without adding physical complexity to the exposure apparatus
Solution Approach 2:
The patent implements feedback through an iterative simulation and adjustment process. The system simulates the exposure process, compares the simulated latent image with the ideal shape, and uses this feedback to refine exposure doses and focal plane positions in subsequent iterations, progressively improving manufacturing precision without increasing device complexity
2Length of stationary object
If higher exposure doses are used to achieve deeper penetration in thick resist layers, then the exposure depth increases, but non-linear effects like bleaching and absorption intensify, causing greater deviation from the ideal shape
Solution Approach 1:
The patent applies dynamics by making the exposure process adaptive and dynamic through iterative refinement. Instead of using a fixed exposure dose, the system dynamically adjusts gray-scale values and focal plane positions based on simulation results, allowing the exposure parameters to evolve and optimize themselves for achieving both deep penetration and high shape accuracy in thick resist layers
Solution Approach 2:
The patent implements parameter changes by systematically varying exposure doses, gray-scale values, and focal plane positions across multiple iterations. The simulation process identifies optimal parameter combinations that compensate for non-linear effects, enabling the system to achieve accurate three-dimensional latent images in thick resist layers without suffering from shape deviations
3Ease of operation
If single focal plane exposure is used to simplify the exposure process, then the process is easier to control, but the ability to compensate for non-linear effects and achieve accurate depth control in thick resist deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the exposure process into multiple discrete focal planes instead of using a single focal plane. The system calculates and applies different exposure doses to each focal plane segment, allowing independent optimization of each layer to compensate for non-linear effects while maintaining overall process control through systematic iteration
Solution Approach 2:
The patent implements another dimension by adding the focal plane dimension to the exposure process. Instead of exposing at a single z-position, the system distributes exposure across multiple focal planes along the depth axis, transforming the problem from two-dimensional (x-y plane) to three-dimensional control, thereby achieving accurate depth control in thick resist layers
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 approach significantly improves the faithfulness of the latent image to the ideal shape, reducing errors and achieving precise depth and shape control in three-dimensional microstructures, even in thick resist layers, by compensating for non-linear effects and absorption processes.
Implementation Method 1
non-linear effects, such as bleaching and absorption
Implementation Method 2
non-linear effects, such as bleaching and absorption
Implementation Method 3
laser noise
Data Source
AI summary
The field of this disclosure is making three-dimensional topographic structures by means of graduated exposure in a photosensitive material, such as a photoresist, photosensitive polymide, or similar. Such patterns may be written either to be used directly as optical, mechanical, fluidic, etc. components, e.g. diffusors, non-reflecting surfaces, Fresnel lenses and Fresnel prisms, computer-generated holograms, lenslet arrays, etc, or to be used as masters for the fabrication of such components by replication. Replication can be done by molding, pressing, embossing, electroplating, etching, as known in the art. This disclosure includes descriptions of using passive absorbing components in thin resist, using high gamma thick resists with high resolution pattern generators, using multiple focal planes including at least one focal plane in the bottom half of the resist, and iterative simulation of patterning and adjustment of an exposure map.