Layered Microlens Structure for Solid-State Imaging Sensitivity
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Solution Overview
Problem
Solid-state imaging devices face challenges in enhancing sensitivity characteristics due to limitations in the design and structure of microlenses, which affect the collection of light and overall imaging performance.
Innovation Solution
The implementation of a solid-state imaging device with a first lens layer and a second lens layer, where the second lens layer is formed at the periphery of each microlens, with a thinner central portion or no second lens layer at the central portion, to increase the light collection area and improve sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer microlens structure is used, then the device structure is simple, but the light collection ability and sensitivity are insufficient
Solution Approach 1:
The microlens is divided into multiple layers (first lens layer and second lens layer) with different refractive indices, allowing each layer to contribute differently to light collection. This segmentation enables improved sensitivity while maintaining manageable structural complexity through modular design.
Solution Approach 2:
The patent uses composite lens structures with materials of different refractive indices arranged in specific patterns (e.g., high refractive index material in the first layer, low refractive index material in the second layer). This composite approach enhances light collection ability and sensitivity by optimizing refraction and focusing at each interface.
2Reliability
If the microlens curvature is increased to improve light collection, then the light collection ability improves, but the manufacturing precision requirements increase
Solution Approach 1:
By dividing the lens into multiple layers with different curvatures and refractive indices, the patent achieves equivalent or superior light collection ability to a single high-curvature lens. Each layer can be manufactured with moderate precision requirements, and their combined optical effect provides enhanced light collection without excessive manufacturing difficulty.
Solution Approach 2:
The patent changes the refractive index parameter across different layers rather than relying solely on curvature increases. By using materials with different refractive indices (e.g., silicon nitride in the first layer, silicon oxide in the second layer), the system achieves improved light collection through refractive index optimization rather than extreme curvature, thereby reducing manufacturing precision requirements.
3Reliability
If the distance from photodiodes to microlenses is shortened, then the sensitivity improves, but the space for wiring and other components is reduced
Solution Approach 1:
The multi-layer composite lens structure achieves enhanced light collection and sensitivity within a compact vertical profile. By optimizing the refractive indices and thicknesses of each layer, the patent accomplishes improved sensitivity without requiring excessive vertical space, thereby preserving horizontal area for wiring and other components.
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 configuration enhances the sensitivity and shading characteristics of the solid-state imaging device by enlarging the light collection area of the microlenses, leading to improved imaging performance.
Implementation Method 1
the second lens layer present at a central portion of each of the first microlenses is thinner than the second lens layer present at the periphery of the first microlens or no second lens layer is present at the central portion of each of the first microlenses
Data Source
AI summary
A solid-state imaging device includes: a first lens layer; and a second lens layer, wherein the second lens layer is formed at least at a periphery of each first microlens formed based on the first lens layer, and the second lens layer present at a central portion of each of the first microlenses is thinner than the second lens layer present at the periphery of the first microlens or no second lens layer is present at the central portion of each of the first microlenses.