Auto-Focus Pixel Microlens Height in Image Sensors
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Solution Overview
Problem
Existing image sensors face challenges in simultaneously optimizing the performance of normal pixels and auto-focus (AF) pixels, which affects the accuracy and speed of image capturing.
Innovation Solution
The image sensor design includes a combination of normal pixels and AF pixels, with AF pixels having a taller microlens than normal pixels, allowing for optimized light focus in both types of pixels, enabling simultaneous performance enhancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the microlens height is increased to improve light focusing for AF pixels, then the AF performance is improved, but the normal pixel performance deteriorates
Solution Approach 1:
The patent implements different microlens heights for different pixel types: taller microlenses for AF pixels to improve light focusing and phase difference detection, and shorter microlenses for normal pixels to maintain their imaging performance. This local differentiation resolves the contradiction by allowing each pixel type to have optimized microlens dimensions suited to its specific function.
2Reliability
If the microlens height is decreased to improve normal pixel performance, then the normal pixel imaging is improved, but the AF pixel performance deteriorates
Solution Approach 1:
The patent implements different microlens heights for different pixel types: taller microlenses for AF pixels to improve light focusing and phase difference detection, and shorter microlenses for normal pixels to maintain their imaging performance. This local differentiation resolves the contradiction by allowing each pixel type to have optimized microlens dimensions suited to its specific function.
3Device complexity
If a single microlens height is used for all pixels, then the device complexity is reduced, but the simultaneous optimization of normal and AF pixel performance becomes difficult
Solution Approach 1:
The patent implements different microlens heights for different pixel types: taller microlenses for AF pixels to improve light focusing and phase difference detection, and shorter microlenses for normal pixels to maintain their imaging performance. This local differentiation resolves the contradiction by allowing each pixel type to have optimized microlens dimensions suited to its specific function.
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 design improves the accuracy and speed of image capturing by optimizing the light receiving focus for both normal and AF pixels, enhancing the overall performance of the image sensor.
Implementation Method 1
a first AF microlens disposed on the first AF pixel and the second AF pixel... A height of the first AF microlens in a vertical direction from a top surface of the semiconductor substrate is greater than a height of the normal microlens
Data Source
AI summary
An image sensor includes a normal pixel, a first auto-focus (AF) pixel, and a second AF pixel, each of the normal pixel, the first AF pixel and the second AF pixel including a photodiode. The image sensor further includes a normal microlens disposed on the normal pixel, and a first AF microlens disposed on the first AF pixel and the second AF pixel. The photodiode of the normal pixel, the photodiode of the first AF pixel, and the photodiode of the second AF pixel are respectively disposed in photo-detecting areas of a semiconductor substrate. A height of the first AF microlens in a vertical direction from a top surface of the semiconductor substrate is greater than a height of the normal microlens in the vertical direction from the top surface of the semiconductor substrate.