Microlens and Color Filter Layout for Blue-Light Image Sensitivity
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Solution Overview
Problem
Existing solid-state imaging elements face challenges in maintaining high light focusing efficiency and sensitivity, particularly for blue light, due to the use of conventional color filters and microlenses with similar refractive indices, leading to reduced light collection and sensitivity in the visible spectrum.
Innovation Solution
Incorporating a color filter with a specific composition and refractive index, including a blue pigment, violet dye, and violet pigment, which has a lower refractive index than the microlenses, and optimized thickness and transmittance characteristics, to enhance light focusing efficiency and sensitivity in the 400-500 nm wavelength range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional color filters with similar refractive indices to microlenses are used, then manufacturing is simplified, but light focusing efficiency and sensitivity decrease
Solution Approach 1:
The patent applies parameter changes by modifying the refractive index parameter of the color filter to be lower than that of the microlens. This creates a refractive index difference that enables effective light focusing while maintaining color filtering functionality, thus resolving the contradiction between manufacturing simplicity and light focusing efficiency.
Solution Approach 2:
The patent uses composite materials by combining specific dyes and pigments in the color filter to achieve the desired optical properties. The color filter includes a first dye absorbing green light, a second dye absorbing red light, and a pigment absorbing blue light, creating a composite material with controlled refractive index and color filtering characteristics.
2Reliability
If color filters with high transmittance in blue region are used, then sensitivity to blue light improves, but light collection efficiency decreases
Solution Approach 1:
The patent optimizes the transmittance parameter of the color filter in the blue wavelength region (400-500 nm) to be within 80-95%, balancing blue light sensitivity with overall light collection efficiency. The microlens thickness and refractive index are also optimized to maximize light focusing while preventing excessive light loss.
Solution Approach 2:
The patent applies local quality by creating different optical properties in different wavelength regions. The color filter has high transmittance specifically in the blue region (400-500 nm) while maintaining appropriate filtering in other regions, and the microlens is designed with specific curvature and thickness to focus blue light effectively without causing chromatic aberration.
3Reliability
If microlens thickness is increased to improve light focusing, then light collection improves, but chromatic aberration increases
Solution Approach 1:
The patent optimizes the microlens thickness parameter to be within 0.5-2.0 μm, which is sufficient to achieve effective light focusing and collection while minimizing chromatic aberration. The refractive index of the microlens material is also optimized to balance focusing power with chromatic aberration control.
Solution Approach 2:
The patent uses spheroidality by designing the microlens with a specific curved surface profile. The microlens has a convex shape with optimized curvature radius that enables effective light focusing while reducing spherical and chromatic aberrations, achieving a balance between light collection and image quality.
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
The solution improves light focusing performance and peak sensitivity by preventing a decrease in light focusing efficiency, particularly for blue light, resulting in enhanced light collection and sensitivity within the 400-500 nm wavelength range.
Implementation Method 1
incident light is focused by microlenses
Implementation Method 2
the color filter has a transmittance that exhibits a maximum value between wavelengths of 400 nm to 500 nm, while also exhibiting a transmittance of 50% between wavelengths of 460 nm to 490 nm, and has a refractive index with a smaller value than a value of a refractive index of the microlenses
Data Source
AI summary
A solid-state imaging element including a semiconductor substrate having a plurality of photoelectric conversion elements, a microlens layer having a plurality of microlenses configured to cause light to enter the photoelectric conversion elements of the semiconductor substrate, and color filters disposed between the semiconductor substrate and the microlens layer.