Multi-Layered Optical Stack Fiducial Alignment
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Solution Overview
Problem
The challenge in nanofabrication is to increase throughput while minimizing process cost and complexity, particularly in achieving desired alignment between layers of optically stacked structures, which affects the performance of optical projection systems.
Innovation Solution
A multi-layered optical stack is qualified for use in an optical projection system by using fiducial marks on each layer, with a processor determining alignment angles and positions to ensure rotational and translational alignment within predetermined thresholds, thereby reducing light artifacts and ghosting effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional alignment methods are used for multi-layered optical stacks, then alignment between layers can be achieved, but the process complexity and cost increase significantly
Solution Approach 1:
Fiducial marks are pre-defined and fabricated on each optical layer during the manufacturing process. These marks serve as predetermined reference points that enable automated alignment systems to quickly determine layer positions and orientations without requiring complex real-time measurement and adjustment procedures, thereby reducing process complexity while maintaining high alignment precision.
Solution Approach 2:
Fiducial marks act as intermediary reference elements between different optical layers. By providing fixed, known reference points on each layer, these marks mediate the alignment process between layers, allowing the system to establish precise relative positions without direct complex measurements between optical components themselves, thus simplifying the overall alignment procedure.
2Manufacturing precision
If traditional alignment methods are used for multi-layered optical stacks, then alignment between layers can be achieved, but the manufacturing cost increases
Solution Approach 1:
Fiducial marks are incorporated into the optical layers during the initial fabrication process rather than being added later through complex alignment procedures. This preliminary integration reduces manufacturing costs by eliminating the need for expensive post-fabrication alignment equipment and procedures, while still achieving the required precision through automated vision-based alignment using the pre-defined marks.
Solution Approach 2:
The fiducial marks provide a simplified optical copy or reference model of the layer geometry that can be easily detected and used for alignment. Instead of requiring complex direct measurements of optical components, the system uses these simple reference marks as proxies, reducing the need for expensive specialized alignment equipment and procedures.
3Productivity
If alignment between optical layers is not precisely controlled, then throughput can be maintained, but light artifacts and ghosting effects increase
Solution Approach 1:
The patent replaces complex mechanical alignment adjustment systems with an automated vision-based alignment system that uses fiducial marks and image processing. This substitution maintains high throughput by eliminating time-consuming manual alignment procedures while achieving precise alignment between layers, thereby preventing light artifacts and ghosting effects without sacrificing productivity.
Solution Approach 2:
The alignment system uses feedback from detecting fiducial marks on each layer to automatically adjust and verify alignment between optical layers. This closed-loop feedback mechanism ensures that alignment precision requirements are met to prevent light artifacts and ghosting, while the automation of the feedback process maintains high manufacturing throughput without manual intervention.
Data Source
AI summary
Methods and systems for qualifying a multi-layered optical stack include providing the multi-layered optical stack including a first optical layer and a second optical layer. The first optical layer includes a first pair of fiducial marks and the second optical layer includes a second pair of fiducial marks Each of the first pair are spaced laterally from each of the second pair such that the first pair and the second pair are visible through the optical stack. A first angle defined between a first reference line connecting the first pair and a global reference line is determined. A second angle defined between a second reference line connecting the second pair and the global reference line is determined. The multi-layered optical stack is qualified for use in the optical projection system based on whether a difference between the first angle and the second angle is less than a predetermined threshold.