Concave Spacer-Wafer Apertures for Wafer-Level Optical Elements
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Solution Overview
Problem
In wafer-level camera lens manufacturing, excess polymer overflow from spacer-wafer apertures reduces production yields and introduces stray light artifacts, while precise control of polymer volume is costly and limits wafer die count due to voids and surface adhesion issues.
Innovation Solution
The use of concave-shaped spacer-wafer apertures with integrated overflow regions allows for a higher die count and improved lens adhesion by increasing the sidewall surface area, reducing voids and overflow issues, and enhancing the adhesion of cured lenses to the aperture sidewalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spacer-wafer aperture diameter is increased to contain overflow material, then yield is improved, but wafer die count is reduced
Solution Approach 1:
The aperture transitions from a conventional flat circular shape to a three-dimensional concave shape with vertical sidewalls and a bottom surface. This dimensional change allows the aperture to contain overflow material vertically within the spacer wafer thickness, eliminating the need to increase the horizontal aperture diameter, thereby maintaining high wafer die count while preventing yield loss from overflow
Solution Approach 2:
The aperture employs concave curved surfaces including vertical sidewalls and a bottom surface, creating a pocket-like structure that efficiently contains overflow material. The curved geometry provides optimal containment volume within the available spacer wafer thickness, preventing material escape while minimizing aperture footprint
2Reliability
If precise control of polymer volume is implemented, then yield loss is reduced, but manufacturing cost increases
Solution Approach 1:
The concave aperture structure pre-provides overflow containment capacity before polymer dispensing occurs. The vertical sidewalls and bottom surface create a reservoir that accommodates excess material, eliminating the need for complex real-time volume control systems while preventing yield loss from overflow
Solution Approach 2:
The aperture geometry itself provides the overflow management function through its concave structure, eliminating the need for external control mechanisms. The structure automatically contains excess material through its physical form, making the system self-regulating without additional complexity
3Strength
If surface treatment is applied to improve adhesion, then lens adhesion is enhanced, but manufacturing complexity increases
Solution Approach 1:
The concave aperture geometry with vertical sidewalls and bottom surface creates a large surface area for lens contact. This curved geometry inherently provides mechanical interlocking and increased adhesion area, achieving strong lens attachment without requiring additional surface treatment processes
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 increases the number of lenses per wafer, reduces manufacturing costs by minimizing yield loss, and enhances image quality by minimizing stray light artifacts through improved lens adhesion and overflow management.
Implementation Method 1
A liquid, such as a UV-curable polymer, is deposited into each aperture and is cast into an intermediate or final lens shape by a fabrication master, mold, or stamp. The casted polymer is then cured to form a solid lens.
Data Source
AI summary
Wafer-level optical elements and the concave spacer-wafer apertures in which they are formed are disclosed. The wafer-level optical elements include a spacer wafer comprising a plurality of apertures. Each aperture has a concave shape in a planar cross-section of the spacer wafer and an overflow region intersecting the planar cross-section. The wafer-level optical elements also include an array of optical elements, each optical element of the array being formed of cured flowable material within a respective one of the plurality of apertures. A portion of the cured flowable material forming each optical element extends into the overflow region of the respective aperture of the plurality of apertures. The spacer wafer includes a plurality of apertures, each of the plurality of apertures having a concave shape in a planar cross-section of the spacer wafer. Each of the plurality of apertures includes an overflow region intersecting the planar cross-section.