Zigzag Via Plugs Light Shielding Image Sensor Optical Black Region
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Solution Overview
Problem
Image sensors face performance degradation due to external light incident on dummy pixel and peripheral circuit regions, which affects the stability of reference signals and electrical characteristics.
Innovation Solution
The implementation of via plugs and interconnections as light shielding members along the interface between the light receiving and optical black regions, arranged in a zigzag pattern to prevent light from propagating from the light receiving region to the optical black region, along with dummy signal patterns to enhance light blocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dummy pixels are disposed along the periphery of the core of main pixels to provide reference signals, then the reference signal generation is enabled, but external light incident on the dummy pixel region causes performance degradation and instability
Solution Approach 1:
A light shielding member is introduced as an intermediary element between the light receiving region and the optical black region (dummy pixel region). This light shielding member blocks external light from reaching the dummy pixels, thereby protecting the reference signal stability without affecting the dummy pixels' ability to generate reference signals when needed.
Solution Approach 2:
The image sensor is divided into distinct regions with clear boundaries: a light receiving region for main pixels, an optical black region for dummy pixels, and a light shielding member positioned between them. This segmentation allows each region to perform its specific function independently, preventing light from spilling over from the light receiving region to the optical black region.
2Object-affected harmful factors
If a light shielding member is introduced to block light from reaching the optical black region, then light blocking is improved, but the structural complexity and manufacturing difficulty increase
Solution Approach 1:
The light shielding member is merged with the existing interconnection structure. The interconnection that normally provides electrical connections is configured to extend along the interface between the light receiving region and optical black region, serving dual purposes: electrical connectivity and light shielding. This integration reduces the need for separate light shielding structures.
Solution Approach 2:
The interconnection structure is given multiple functions: it provides electrical connections between pixels and circuitry, and simultaneously serves as a light shielding member by extending along the region interface. This multi-functionality reduces the overall device complexity by eliminating the need for dedicated light shielding structures.
3Object-affected harmful factors
If the interconnection extends longitudinally along the interface between optical black region and light receiving region, then light shielding effectiveness is improved, but the manufacturing precision requirements increase due to alignment constraints
Solution Approach 1:
The light shielding function is segmented into multiple discrete via plugs arranged along the interface rather than requiring a continuous structure. These via plugs can be positioned at specific intervals, reducing the cumulative alignment tolerance requirements compared to a continuous light shielding structure that would require precise alignment over the entire interface length.
Solution Approach 2:
Instead of placing light shielding via plugs at every possible position along the interface, the invention uses selectively positioned via plugs at key locations. This partial action approach provides sufficient light blocking effectiveness while significantly reducing the number of alignment operations required during manufacturing.
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
Effectively prevents light from reaching the optical black region, thereby improving the stability of reference signals and electrical characteristics, and allowing for hydrogen passivation without impeding the process, thus enhancing the overall performance of the image sensor.
Implementation Method 1
via plugs and interconnections as light shielding members along the interface between the light receiving and optical black regions, arranged in a zigzag pattern to prevent light from propagating from the light receiving region to the optical black region
Data Source
AI summary
An image sensor having a light receiving region and an optical black region includes a semiconductor substrate, an interconnection disposed on the semiconductor substrate and extending along an interface between the light receiving region and the optical black region, and via plugs disposed between the interconnection and the semiconductor substrate and serving as light shielding members at the interface. The via plugs are arranged in a zigzagging pattern along the interface.