Wafer-Level Optical Element Stack Assemblies
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Solution Overview
Problem
Existing optoelectronics modules for applications like 3D imaging and distance measurement face challenges in efficiently fabricating optical element stack assemblies that can effectively project and sense structured light patterns, particularly in achieving precise spacing and alignment of optical elements for optimal performance.
Innovation Solution
The development of wafer-level methods for fabricating optical element stack assemblies, which involve attaching wafers with optical elements to form sub-stacks and then separating them into individual assemblies using techniques like vacuum injection molding and adhesive attachment, allowing for precise placement and spacing of optical elements such as diffractive optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional individual fabrication methods are used for optical element stack assemblies, then each assembly can be carefully aligned, but the fabrication process is time-consuming and low productivity
Solution Approach 1:
Multiple optical element stack assemblies are fabricated simultaneously by attaching multiple wafers together to form a wafer stack, which is then processed as a single unit. This merging approach maintains alignment precision through collective processing while dramatically increasing productivity by producing multiple assemblies in parallel rather than individually.
Solution Approach 2:
The fabrication process is segmented into distinct stages: first attaching wafers with optical elements to form a wafer stack, then attaching spacer wafers to define spacing, and finally separating the stack into individual assemblies. This segmentation allows precision to be maintained during the bulk processing phase while enabling high-volume production, with the separation step creating individually precise assemblies from the collectively processed stack.
2Productivity
If wafer-level methods are used to fabricate multiple assemblies in parallel, then productivity increases, but achieving precise spacing and alignment becomes more difficult
Solution Approach 1:
Spacer wafers are introduced as intermediary elements between the optical element wafers. These spacer wafers define and maintain precise spacing between optical elements in different wafers through their lateral portions that extend between the wafers. This intermediary approach enables precise spacing control in parallel-fabricated assemblies without compromising throughput, as the spacers are attached collectively to the entire wafer stack.
Solution Approach 2:
The spacer wafers are attached to the wafer stack before the final separation into individual assemblies. This preliminary action establishes the precise spacing configuration for all assemblies simultaneously during the bulk processing phase, ensuring spacing precision is built into the structure before individual separation, thereby maintaining manufacturing precision while achieving high productivity.
3Manufacturing precision
If complex alignment procedures are implemented for each assembly, then alignment accuracy improves, but the fabrication process becomes more complex and time-consuming
Solution Approach 1:
Multiple wafers with optical elements are attached together in a collective alignment process rather than aligning each assembly individually. This merging approach reduces fabrication process complexity by performing alignment operations on the entire wafer stack simultaneously, while still achieving the required optical element alignment precision through the unified attachment 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
This approach enables the efficient fabrication of multiple optical element stack assemblies in parallel, allowing for precise control over the spacing between optical elements, enhancing the performance of optoelectronic modules in imaging and distance measurement applications by ensuring accurate projection and sensing of structured light patterns.
Implementation Method 1
using a single vacuum injection technique to form upper and lower spacers on opposite surfaces of the second wafer
Implementation Method 2
The first and second wafers are attached such that each optical element is disposed between the first and second wafers
Data Source
AI summary
The present disclosure describes optical element stack assemblies that include multiple substrates stacked one over another. At least one of the substrates includes an optical element, such as a DOE, on its surface. The stack assemblies can be fabricated, for example, in wafer-level processes.