Image Sensor Pixel Separation Layout for Leakage Current Detection
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Solution Overview
Problem
Current image sensors lack effective methods to detect and address leakage currents during manufacturing, which can lead to defects and reduced reliability.
Innovation Solution
The image sensor design includes verification pixel separation structures with pads and contacts that apply bias voltage and detect currents, allowing for the detection of leakage currents before the formation of critical components like color filters and micro lenses, enabling early compensation for defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If verification pads and contacts are added to detect leakage current, then reliability is improved, but device complexity increases
Solution Approach 1:
The pixel separation structure is divided into multiple segments: regular pixel separation structures for normal pixel isolation, and verification pixel separation structures with embedded pads and contacts for leakage detection. This segmentation allows the system to maintain normal pixel functionality while adding detection capabilities through dedicated verification structures.
Solution Approach 2:
Verification pads and contacts serve as intermediary elements between the pixel separation structures and external measurement equipment. These intermediary components enable leakage current detection without directly interfering with the normal operation of active pixels, as they are positioned in dummy pixel regions.
2Manufacturing precision
If verification pixel separation structures with pads and contacts are implemented, then manufacturing defect detection is improved, but ease of manufacture deteriorates
Solution Approach 1:
The verification pads and contacts are formed during the initial manufacturing stages before critical components like color filters and micro lenses are added. This preliminary action allows leakage current detection capabilities to be built into the structure early in the manufacturing process, enabling defect detection before final assembly.
Solution Approach 2:
The verification pads and contacts are selectively placed only in dummy pixel regions, while active pixel regions maintain their standard structure. This local quality approach ensures that leakage detection functionality is added only where needed for verification, without modifying or complicating the manufacturing of active imaging areas.
3Reliability
If dummy pixel region with verification structures is added, then reliability is improved, but area of stationary object increases
Solution Approach 1:
The verification functionality is extracted and isolated into dedicated dummy pixel regions, separate from the active pixel array. This extraction allows the verification structures to occupy minimal space in non-critical areas while maintaining full detection capability, preventing the need to expand the active imaging area.
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 approach improves the reliability of image sensors by detecting and mitigating leakage currents during the manufacturing process, preventing defects and enhancing overall sensor performance.
Implementation Method 1
a first contact among the plurality of contacts is configured to apply a current to a first portion of the plurality of pixel separation structures
Implementation Method 2
a second contact among the plurality of contacts is configured to detect a current from a second portion of the plurality of pixel separation structures
Data Source
AI summary
An image sensor including a substrate including a first surface and a second surface, and including a plurality of photoelectric conversion elements therein. A plurality of pixels may be provided in the substrate, a plurality of pixel separation structures may be configured to separate the plurality of pixels, and a plurality of contacts may be respectively connected to the plurality of pixel separation structures. A first contact among the plurality of contacts may be configured to apply a current to a first portion of the plurality of pixel separation structures, and a second contact among the plurality of contacts may be configured to detect a current from a second portion of the plurality of pixel separation structures.