Segmented Microlens Design for Solid-State Imaging Device Thickness Reduction
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Solution Overview
Problem
Conventional solid-state imaging devices face challenges in downsizing due to the design of microlens portions with large curvature radii, leading to long focal lengths and increased device thickness, which hinders further miniaturization and results in a trade-off between sensitivity and flare light incidence.
Innovation Solution
The design includes microlens portions with a height greater than the transmission portions, made of the same material, with gaps between adjacent microlens portions and connected transmission portions, allowing for a shorter focal length and reduced thickness, enhancing light focusing and minimizing flare light incidence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If microlens portions are designed with large curvature radii, then light sensitivity is improved, but device thickness increases and downsizing is hindered
Solution Approach 1:
The lens element is segmented into multiple regions: a microlens portion with a first curvature radius for light focusing, and a lower portion with a second curvature radius that is larger than the first. This segmentation allows each region to have optimized curvature for its specific function, enabling reduced overall thickness while maintaining light sensitivity.
Solution Approach 2:
Different regions of the lens element are assigned different local optical properties through varying curvature radii. The microlens portion has a smaller curvature radius for effective light focusing, while the lower portion has a larger curvature radius to reduce total thickness and control flare light, achieving local optimization of optical performance.
2Measurement precision
If microlens portions are designed with large curvature radii, then light sensitivity is improved, but device downsizing is hindered
Solution Approach 1:
The lens element is divided into a microlens portion and a lower portion with different curvature radii. This segmentation enables the microlens to maintain effective focusing capability with smaller dimensions, while the lower portion with larger curvature reduces overall volume, facilitating device downsizing without sacrificing sensitivity.
Solution Approach 2:
The curvature radius parameter is changed across different regions of the lens element. By using a smaller curvature radius in the microlens portion and a larger curvature radius in the lower portion, the optical performance is maintained while the overall device volume is reduced, enabling downsizing.
3Ease of manufacture
If transmission portions are formed connected with no gaps, then manufacturing complexity is reduced, but flare light incidence increases
Solution Approach 1:
The lens element uses different curvature radii in different regions to locally control light paths. The microlens portion with smaller curvature focuses light effectively, while the lower portion with larger curvature helps redirect flare light, achieving both manufacturing simplicity and flare light control through local optical property variations.
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 enables downsizing of solid-state imaging devices, improves light sensitivity, and reduces flare light incidence, balancing sensitivity characteristics with minimized flare light effects.
Implementation Method 1
Each of the lens elements includes a microlens portion which protrudes from the transmission portion and is aligned with the photoelectric conversion element... light from the microlens portion is transmitted toward the photoelectric conversion element
Data Source
AI summary
A solid-state imaging device including a semiconductor substrate including photoelectric conversion elements formed in first and second directions, color filters of respective colors formed on the semiconductor substrate, and lens elements formed on the color filters. Each of the lens elements includes a transmission portion and a microlens portion, the microlens portion has a height greater than a height of the transmission portion, the transmission portion is formed between the microlens portion and the color filter such that light from the microlens portion is transmitted toward the photoelectric conversion element, and the lens elements are formed such that the microlens portions have gaps between the microlens portions adjacent in the first and second directions, and a third direction intersecting the first and second directions at 45° , and that the transmission portions are formed connected to each other with no gaps therebetween in the first, second and third directions.