Wafer Alignment Features Using Capillary Self-Alignment
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Solution Overview
Problem
Existing optical assemblies face challenges in efficiently aligning and replicating optical elements with high precision and density, particularly in microfluidic systems, often requiring complex and multi-step alignment processes.
Innovation Solution
The use of microfluidic alignment features, utilizing capillary action with liquid droplets to align optical elements, and a replication tool with contact spacer portions that adapt to substrate roughness, allowing for self-assembly and precise alignment without additional steps for spacer addition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional alignment methods are used for optical elements, then alignment precision can be achieved, but the process complexity increases and manufacturing efficiency decreases
Solution Approach 1:
The patent implements self-alignment through capillary action where liquid droplets automatically draw the upper wafer onto the lower wafer without external manipulation. The alignment features (protrusions and recesses) guide the wafers into precise alignment automatically during the bonding process, eliminating the need for complex external alignment equipment and procedures.
Solution Approach 2:
The patent introduces liquid droplets as an intermediary substance that facilitates alignment and bonding. The liquid creates capillary forces that pull the wafers together and hold them in alignment during the bonding process, serving as a mediator between the two wafers to achieve precise alignment without complex mechanical systems.
2Ease of manufacture
If conventional replication tools are used, then optical elements can be replicated, but additional steps for spacer addition are required increasing manufacturing steps
Solution Approach 1:
The patent combines the spacer function with the replication tool itself by incorporating contact spacer portions directly into the tool structure. This merging eliminates the need for separate spacer addition steps, as the spacers are inherently part of the replication process, reducing the total number of manufacturing steps while maintaining ease of manufacture.
Solution Approach 2:
The replication tool is designed with multi-functionality, serving both as the replication surface for optical elements and as the spacer provider through its contact spacer portions. This universal design allows a single tool to perform multiple functions (replication and spacing) simultaneously, improving manufacturing efficiency by eliminating separate spacer addition operations.
3Area of stationary object
If dense packing of optical elements is achieved, then area utilization improves, but alignment precision becomes more difficult to maintain
Solution Approach 1:
The patent divides the replication tool into multiple discrete replication sections, each capable of forming individual optical elements. This segmentation allows for dense packing of elements while maintaining precise alignment through the distributed alignment features (multiple protrusions and recesses) that work together to ensure accurate positioning of each element during the self-alignment process.
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 high-precision, dense packing of optical elements with reduced process complexity, maintaining optical performance and enhancing manufacturing efficiency.
Implementation Method 1
depositing liquid droplets on the first side of the first wafer, and aligning the first wafer and the second wafer with respect to each other and bringing the second wafer and the first side of the first wafer together, with liquid droplets between the first wafer and the second wafer, the upper alignment features contacting the liquid droplets on the lower alignment features on the first side of the first wafer, and thereby causing the first wafer to align with the second wafer by capillary action
Data Source
AI summary
A method of manufacturing a plurality of optical elements includes providing a first wafer (200) having lower alignment features (192) arranged on a first surface of the substrate, providing a second wafer (201) comprising, on a replication side, a plurality of replication sections, each replication section defining a surface structure of one of the optical elements, the second wafer (201) further comprising upper alignment features (194) protruding, on the replication side, further than an outermost feature of the replication sections, depositing liquid droplets (196) on the first side of the first wafer (200), and bringing the second wafer (201) and the first side of the first wafer (200) together, with liquid droplets (196) between the first wafer (200) and the second wafer (201), the upper alignment features (194) contacting the liquid droplets (196) on the lower alignment features (192) on the first side of the first wafer (200), and thereby causing the second wafer (201) to align with the first wafer (200) by capillary action.