Image Sensor Guard Ring for Pixel Noise Isolation
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Solution Overview
Problem
Current image sensing devices face challenges in accurately discriminating detection signals between adjacent unit pixels, leading to noise interference and reduced efficiency in depth measurement applications, particularly in 3D sensing technologies.
Innovation Solution
The proposed image sensing device incorporates a guard ring region surrounding the control region to control photocharge movement and a drain region to remove noise electrons, with control signals having phase differences applied to unit pixels in a (2×2) matrix array to enhance signal discrimination and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If photocharges are moved through the substrate using a control region, then photocharge transport efficiency is improved, but noise electrons from adjacent unit pixels can interfere with detection signals
Solution Approach 1:
The substrate is divided into multiple unit pixels, each with its own control region and detection region. The guard ring region acts as a segmentation boundary that electrically isolates adjacent unit pixels, preventing noise electrons from one pixel from interfering with the detection signals of neighboring pixels while maintaining efficient photocharge transport within each segmented unit.
Solution Approach 2:
The guard ring region serves as an intermediary structure between adjacent control regions. It is configured to receive a different voltage than the control region, creating an electrical barrier that mediates the interaction between neighboring pixels by blocking noise electron flow while allowing controlled photocharge movement through the control region.
2Productivity
If the detection region is positioned to surround the control region, then photocharge capture efficiency is improved, but device structure complexity increases
Solution Approach 1:
The detection region is merged with the control region by positioning the detection region to surround the control region within the same unit pixel. This integration allows the control region to perform dual functions: transporting photocharges generated within its boundaries and capturing photocharges that arrive from the surrounding detection region, thereby improving overall photocharge capture efficiency without requiring separate structures.
Solution Approach 2:
The control region is designed with multi-functionality to serve both as a photocharge transport pathway for internally generated photocharges and as a capture region for photocharges from the surrounding detection region. This universal design reduces the need for additional specialized structures, maintaining relatively simple device architecture while achieving high photocharge capture efficiency.
3Measurement precision
If guard ring regions are added to surround control regions, then signal discrimination between adjacent pixels is improved, but manufacturing complexity increases
Solution Approach 1:
The guard ring region is implemented with local quality by configuring it to receive a different voltage than the control region, creating a localized electrical property difference at the boundary between adjacent pixels. This local voltage differentiation enhances signal discrimination accuracy by establishing clear electrical boundaries without requiring complex structural modifications throughout the entire device.
Solution Approach 2:
The guard ring region utilizes parameter changes by varying the voltage applied to it relative to the control region. This voltage parameter differentiation creates an electrical barrier that improves signal discrimination between adjacent pixels. The solution achieves enhanced measurement precision through a simple parameter change (voltage level) rather than through complex structural or material modifications.
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 configuration improves electron detection efficiency, reduces noise interference between pixels, and enables more accurate depth measurement by effectively capturing and processing photocharges, enhancing the overall performance of the image sensing device in 3D sensing applications.
Implementation Method 1
a photoelectric conversion region disposed in a substrate, and configured to generate photocharges in response to incident light
Data Source
AI summary
An image sensing device includes a plurality of unit pixels, wherein each of the unit pixels includes a photoelectric conversion region disposed in a substrate, and configured to generate photocharges in response to incident light, a control region disposed in the substrate and configured to receive a control signal and generate a current in the substrate based on the control signal to carry and move the photocharges generated in the photoelectric conversion region, a detection region disposed in the substrate and configured to receive the current and to capture the photocharges carried by the current and a guard ring region configured to surround the control region, and wherein the hole current flows between the control region and the guard ring region.