Pixel Isolation Region Layout for Imaging Leakage Suppression
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Solution Overview
Problem
In imaging devices, unintended movement of charge, known as leakage current, degrades image quality by generating noise, and existing technologies struggle to effectively prevent this movement between and within pixels.
Innovation Solution
The imaging device incorporates a semiconductor substrate with specific impurity regions and contacts of different conductivity types, where the third impurity region acts as a potential barrier to block minority carriers, reducing leakage current by recombination and increasing impurity concentration at the surface, and the first contact is electrically connected to this region to enhance blocking efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photoelectric converter and charge accumulation region are formed on a semiconductor substrate, then image sensing capability is improved, but leakage current between and within pixels increases degrading image quality
Solution Approach 1:
The semiconductor substrate is divided into multiple pixels with isolated charge accumulation regions. Each pixel is separated by isolation regions that prevent charge leakage between adjacent pixels, while maintaining individual charge storage capability within each pixel unit.
Solution Approach 2:
Different regions of the semiconductor substrate are doped with different conductivity types to create localized electrical properties. The third impurity region with opposite conductivity type forms a potential barrier specifically at critical interfaces to block minority carrier leakage while maintaining proper charge accumulation in the first impurity region.
Solution Approach 3:
The third impurity region acts as an intermediary barrier between the first and second impurity regions. This intermediate region with opposite conductivity type creates a potential barrier that mediates the interaction between adjacent charge accumulation regions, preventing direct charge leakage while allowing proper electrical isolation.
2Object-generated harmful factors
If impurity regions are added to block leakage current, then leakage current is reduced, but device complexity increases
Solution Approach 1:
The isolation region is formed by integrating the third impurity region directly into the semiconductor substrate alongside the first and second impurity regions. This merging approach creates a unified doped structure that provides both charge accumulation functionality and leakage blocking without requiring separate isolation components or additional processing layers.
Solution Approach 2:
The third impurity region serves multiple functions simultaneously: it acts as an isolation barrier between pixels, provides electrical connection pathways through the first contact, and creates potential barriers to block minority carrier leakage. This multi-functionality reduces the need for separate structures for each function.
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 significantly reduces leakage current, both within and between pixels, thereby improving image quality by minimizing noise and enhancing the reliability of charge accumulation and signal detection.
Implementation Method 1
The third impurity region contains impurities of a second conductivity type that differs from the first conductivity type... blocking minority carriers, reducing leakage current by recombination
Implementation Method 2
the third impurity region acts as a potential barrier to block minority carriers
Implementation Method 3
a photoelectric converter that converts incident light into a charge
Implementation Method 4
The first impurity region accumulates the charge
Data Source
AI summary
An imaging device includes a semiconductor substrate, a photoelectric converter that converts incident light into a charge, a first impurity region located in the semiconductor substrate, where the first impurity region accumulates the charge and contains impurities of a first conductivity type, a second impurity region located in the semiconductor substrate, where the second impurity region contains impurities of the first conductivity type and is different from the first impurity region, a third impurity region located in the semiconductor substrate, between the first impurity region and the second impurity region in plan view, where the third impurity region contains impurities of a second conductivity type that differs from the first conductivity type, and a first contact located on the semiconductor substrate and electrically connected to the third impurity region. The first contact includes a semiconductor containing impurities of the second conductivity type.