Microlens Layering to Reduce Bridging and Light Loss
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Solution Overview
Problem
Current microlens manufacturing techniques fail to adequately reduce spacing between microlenses without causing bridging, leading to light loss and optical interference in optical sensors, and are costly due to complex alignment and potential damage to photosensitive areas.
Innovation Solution
A method involving the formation of first microlens structures by photolithography, followed by deformation to create curved shapes, and then forming second microlens structures that extend into spacer regions, using a single mask for both processes and diffusion plasma treatment to adjust curvature and prevent bridging, while maintaining precision and avoiding damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If microlenses are spaced closely together to reduce light loss and improve quantum efficiency, then quantum efficiency improves, but bridging occurs between microlenses causing optical interference
Solution Approach 1:
The patent applies segmentation by dividing the microlens formation into two separate photolithography processes: first forming initial microlens structures with spacing, then forming second microlens structures that extend into the spacer regions. This segmentation allows precise control over the final microlens spacing to prevent bridging while maintaining high quantum efficiency.
Solution Approach 2:
The patent uses another dimension by forming microlenses in two sequential layers/dimensions through separate photolithography processes. The second microlens structures are formed to extend into the spacer regions between the first microlens structures, effectively utilizing the vertical and lateral dimensions to achieve precise spacing control and eliminate bridging.
2Ease of manufacture
If standard photolithography techniques are used to form microlenses, then manufacturing is simple, but spacing between microlenses cannot be sufficiently reduced without bridging
Solution Approach 1:
The manufacturing process is segmented into two distinct photolithography steps: first creating initial microlens structures with adequate spacing, then forming second microlens structures that extend into the spacer regions. This segmentation enables precise spacing control while maintaining manufacturing simplicity through standard photolithography techniques.
Solution Approach 2:
The first photolithography process performs a preliminary action by forming initial microlens structures with sufficient spacing to prevent bridging. The second photolithography process then adds microlens structures that extend into the spacer regions, achieving precise spacing control without requiring advanced lithography techniques.
3Manufacturing precision
If multiple photolithography processes with different masks are used to reduce spacing, then spacing between microlenses is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the microlens formation into two photolithography processes that use the same mask design. The first process forms initial microlens structures, and the second process forms additional microlens structures that extend into the spacer regions. This merging approach reduces device complexity by eliminating the need for different masks and complex alignment procedures while achieving precise spacing control.
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 reduces spacing between microlenses, eliminates bridging, enhances quantum efficiency, and reduces manufacturing costs by simplifying the process and protecting sensitive areas, resulting in improved light focusing and reduced optical interference.
Implementation Method 1
The microlens structures are then subjected to thermal creep, i.e. become liquid from the action of heat in order to allow the wetting of the structures on the substrate. The wetting corresponds to a natural deformation of a liquid in contact with the surface of a solid.
Implementation Method 2
The microlens structures are then subjected to thermal creep, i.e. become liquid from the action of heat in order to allow the wetting of the structures on the substrate. The wetting corresponds to a natural deformation of a liquid in contact with the surface of a solid.
Implementation Method 3
diffusion plasma treatment to adjust curvature and prevent bridging
Data Source
AI summary
In accordance with an embodiment, a method for manufacturing an optical device on a support substrate includes: forming first microlens structures on the support substrate using a first photolithography process such that the first microlens structures are separated from one another; deforming the first microlens structures so as to give the first microlens structures a curved shape, wherein the first microlens structures are separated from one another by spacer regions after deformation; forming second microlens structures substrate using a second photolithography process such that the second microlens structures extend over the first microlens structures; and deforming the second microlens structures such that the second microlens structures have a curved form matching the curved shape of the first microlens structures and extend partly into the spacer regions between the first microlens structures.