Doped Pixel Isolation Structure for Low-Dark-Current Image Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current image sensors face challenges in achieving improved electrical and optical performance characteristics, particularly in reducing power consumption and dark current issues, which affect their efficiency and resolution in portable devices.
Innovation Solution
The design incorporates a semiconductor substrate with a pixel isolation structure that includes a semiconductor pattern vertically penetrating the substrate, a sidewall insulating pattern, and a dopant region with varying dopant concentrations, along with a contact plug connected to the dopant region, to enhance pixel isolation and reduce dark current, thereby improving electrical and optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pixel isolation structure is introduced to reduce dark current, then electrical performance is improved, but device complexity increases
Solution Approach 1:
The pixel isolation structure is divided into multiple functional components: a semiconductor pattern extending into the substrate, a sidewall insulating pattern for electrical isolation, and a dopant region for electrical control. This segmentation allows each component to address specific aspects of dark current reduction while maintaining manufacturability through standardized processing steps.
Solution Approach 2:
The dopant region is strategically positioned within the semiconductor pattern at locations where electrical isolation is most critical. By concentrating dopants in specific zones rather than uniformly distributing them, the structure achieves effective dark current reduction with minimal impact on overall device complexity and manufacturing processes.
2Productivity
If signal transfer speed is increased, then productivity is improved, but signal delay may increase due to structural complexity
Solution Approach 1:
The semiconductor pattern acts as an intermediary structure that provides both mechanical support and electrical pathways. By designing the semiconductor pattern with optimized geometry and positioning the dopant region strategically, fast signal transfer paths are created while the sidewall insulating pattern prevents signal leakage, thereby reducing effective signal delay despite the added structural elements.
3Use of energy by moving object
If power consumption is reduced, then use of energy is improved, but electrical performance may deteriorate
Solution Approach 1:
The dopant region is configured to create internal electrical fields that passively repel charge carriers away from the pixel isolation interfaces. This self-service mechanism reduces dark current without requiring external power input or active control circuits, thereby maintaining electrical performance while minimizing additional power consumption.
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 enhances the image sensor's ability to reduce dark current and signal delay, leading to improved electrical and optical performance characteristics, including reduced power consumption and increased resolution, making it suitable for portable devices.
Implementation Method 1
a dopant region in at least a portion of the semiconductor pattern
Implementation Method 2
a sidewall insulating pattern between a sidewall of the semiconductor pattern and the semiconductor substrate
Implementation Method 3
photoelectric conversion regions of second conductivity type respectively provided in the pixel regions
Data Source
AI summary
An image sensor includes a semiconductor substrate of first conductivity type having first and second surfaces and including pixel regions, photoelectric conversion regions of second conductivity type respectively provided in the pixel regions, and a pixel isolation structure disposed in the semiconductor substrate to define the pixel regions and surrounding each of the photoelectric conversion regions. The pixel isolation structure includes a semiconductor pattern extending from the first surface to the second surface of the semiconductor substrate, a sidewall insulating pattern between a sidewall of the semiconductor pattern and the semiconductor substrate, and a dopant region in at least a portion of the semiconductor pattern.