Microlens Curvature Control in Image Sensor Lens Arrays
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Solution Overview
Problem
Current image sensors face challenges in optimizing the curvature of microlenses, which affects their performance in light collection and autofocus capabilities, leading to suboptimal image sensing outcomes.
Innovation Solution
A method of manufacturing image sensors that involves forming a lens material layer with isolation grooves and internal grooves of varying shapes, allowing for the creation of microlenses with different curvatures through a reflow process and etch-back techniques, enabling precise control over lens patterns and heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional microlens formation methods are used, then manufacturing process is simple, but lens curvature optimization is limited affecting autofocus capability
Solution Approach 1:
The patent forms preliminary grooves in the lens material layer before the reflow process. These grooves serve as pre-defined templates that guide the curvature formation during reflow, enabling precise lens curvature control without requiring complex post-processing steps. The grooves are formed at specific positions and depths to predetermined lens curvature profiles.
Solution Approach 2:
The patent utilizes the reflow process to change the physical state and flow characteristics of the lens material. By controlling reflow temperature and duration parameters, the lens material flows to fill the preliminary grooves, transforming the material from a rigid state to a flowing state and back, thereby achieving precise curvature optimization.
2Use of energy by moving object
If microlens curvature is increased for better light collection, then light collection efficiency improves, but manufacturing precision becomes harder to control
Solution Approach 1:
The patent applies different groove configurations to different regions of the lens array. Each groove pattern is locally optimized for its specific position, allowing high curvature where light collection is critical while maintaining uniformity through localized control. This enables each microlens to have optimal curvature without compromising overall manufacturing precision.
3Adaptability or versatility
If multiple lens curvatures are formed for different photoelectric conversion devices, then autofocus capability improves, but manufacturing complexity increases
Solution Approach 1:
The patent divides the lens array into multiple segments or regions, each with its own groove pattern configuration. This segmentation allows different curvature types to be formed in different regions corresponding to different photoelectric conversion device types. Each segment can be independently optimized while using the same overall manufacturing process.
Solution Approach 2:
The patent employs asymmetric groove patterns where grooves in different regions have different shapes, depths, or spacing. This asymmetry enables the formation of microlenses with different curvatures tailored to specific photoelectric conversion devices, enhancing autofocus capability through diversified lens designs without requiring fundamentally different manufacturing 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 enhances the autofocus capability and sensitivity of image sensors by optimizing the curvature of microlenses, improving image sensing performance while simplifying the manufacturing process and reducing costs.
Implementation Method 1
forming lens patterns having different curvatures using the lens material layer in which the isolation groove and the first and second internal grooves are formed
Data Source
AI summary
A method of manufacturing an image sensor includes forming a first chip structure including a circuit wiring structure, forming a second chip structure on the first chip structure, the second chip structure including a plurality of photoelectric conversion device regions, forming a lens material layer on the second chip structure, forming an isolation groove defining a plurality of lens regions in the lens material layer, forming internal grooves in the plurality of lens regions of the lens material layer surrounded by the isolation groove, and forming lens patterns using the lens material layer in which the isolation groove and the internal grooves are formed.