Microlens Matrix Pitch Offset for Higher-Sensitivity Image Sensors
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 than or equal to the pixel dimensions and do not utilize the entire surface for light collection.
Innovation Solution
The image sensor design includes 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
1Manufacturing precision
If microlenses are arranged with the same pitch as the pixel matrix, then the manufacturing is simpler, but the light collection surface area is limited and sensitivity is reduced
Solution Approach 1:
The patent applies asymmetry by deliberately designing the microlens matrix with a different pitch than the pixel matrix. Specifically, the microlens pitch is made larger than the pixel pitch, creating an asymmetric relationship between the two matrices. This allows the microlenses to be positioned such that their optical axes align with the photosensitive areas while extending the light collection surface beyond the pixel boundaries, thereby increasing the fill factor and sensitivity without compromising positioning precision.
2Ease of manufacture
If microlenses are made smaller to fit within pixel boundaries, then the manufacturing is easier, but the light collection efficiency is reduced
Solution Approach 1:
The patent applies dimensionality change by extending the microlens matrix beyond the traditional pixel boundary constraints. Instead of confining microlenses strictly within each pixel area, the invention allows microlenses to span across multiple pixel regions in the lateral direction. This dimensional extension enables the microlenses to collect light from a larger area while still focusing it onto the photosensitive areas, thereby improving light collection efficiency without significantly complicating the manufacturing process.
3Reliability
If the microlens pitch is increased to cover peripheral circuit areas, then the sensitivity is improved, but the alignment with pixel matrix becomes more complex
Solution Approach 1:
The patent applies local quality by implementing different pitch values in different regions or directions. Specifically, the microlens matrix is designed with a pitch that is optimized for light collection in the lateral direction (larger pitch to extend over peripheral areas), while maintaining appropriate alignment in the vertical direction. This localized optimization allows the sensor to achieve higher sensitivity by utilizing peripheral circuit areas for light collection, while the alignment complexity is managed through selective pitch adjustment rather than uniform changes throughout the entire matrix.
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 conventional designs.
Implementation Method 1
a microlens associated with the pixel, arranged facing the substrate, the microlenses being arranged in a matrix in N rows and M columns
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.