Microlens-Pixel Pitch Mismatch for Higher Image Sensor Sensitivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional image sensors have limitations in light collection due to the surface area occupied by peripheral circuits, which reduces their sensitivity, as the microlenses are typically smaller or equal in size to the pixels and do not utilize the entire surface for light collection.
Innovation Solution
The image sensor design features a microlens matrix with larger dimensions than the pixel matrix, extending over the peripheral circuit area to increase the light collection surface, with the pitch of the microlens matrix being greater than the pixel matrix, allowing for enhanced sensitivity by using the peripheral circuit surface for light collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the photosensitive area is increased to improve light collection, then sensitivity is improved, but the area available for control transistors and peripheral circuits is reduced
Solution Approach 1:
The pixel structure is segmented into distinct functional zones: a photosensitive area for light detection, a control area for transistors, and a peripheral circuit area. This segmentation allows each zone to be optimized independently, enabling the photosensitive area to be maximized without compromising the space needed for control electronics.
Solution Approach 2:
The invention utilizes the vertical dimension by stacking multiple layers including the semiconductor substrate, microlens layer, and peripheral circuit layer. This three-dimensional arrangement allows photosensitive areas to be positioned directly beneath microlenses for optimal light collection, while control transistors and peripheral circuits are arranged in separate layers, effectively resolving the area conflict through spatial separation in multiple dimensions.
2Area of stationary object
If the microlens matrix pitch is increased to cover peripheral circuit areas, then light collection surface is improved, but the alignment between microlenses and photosensitive areas becomes more difficult
Solution Approach 1:
The microlens matrix is designed with adjustable pitch parameters that can be optimized based on the specific sensor configuration. The pitch in the first direction can differ from the pitch in the second direction, allowing dynamic adaptation to the layout of photosensitive areas and peripheral circuits, thereby maintaining alignment precision while expanding coverage.
Solution Approach 2:
The invention employs variable pitch parameters for the microlens matrix, where the pitch can be independently adjusted in different directions (first direction vs. second direction). This parameter flexibility allows the microlens positions to be precisely aligned with photosensitive areas even when the overall matrix needs to extend over peripheral circuit regions, resolving the conflict between coverage area and alignment precision.
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 significantly increases the sensitivity of the image sensor by utilizing the previously unused peripheral circuit surface for light collection, resulting in improved light collection efficiency and sensitivity compared to sensors with smaller microlenses.
Implementation Method 1
a microlens extending over substantially the entire surface of the pixel and configured to concentrate the incident light on the photosensitive area of the pixel
Implementation Method 2
Each pixel typically comprises a photosensitive area in which the incident light is converted into electron-hole pairs
Data Source
AI summary
The present disclosure relates to an image sensor including a plurality of pixels formed in and on a semiconductor substrate and arranged in a matrix with N rows and M columns, with N being an integer greater than or equal to 1 and M an integer greater than or equal to 2. A plurality of microlenses face the substrate, and each of the microlenses is associated with a respective pixel. The microlenses are arranged in a matrix in N rows and M columns, and the pitch of the microlens matrix is greater than the pitch of the pixel matrix in a direction of the rows of the pixel matrix.