Image Sensor Charge-Holding Trench for Higher Saturation Charge
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Solution Overview
Problem
Solid-state imaging elements face challenges in achieving a larger saturated charge amount in their charge-holding sections, which limits their dynamic range and imaging performance.
Innovation Solution
Incorporating a trench section with a first semiconductor layer covering a base in the charge-holding section of the imaging device, which increases the boundary area between different semiconductor regions, enhancing charge transfer and storage capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conventional charge-holding section is used without a trench structure, then the device complexity is low, but the saturated charge amount is limited
Solution Approach 1:
The patent introduces a trench section that extends in the thickness direction (vertical dimension) of the charge-holding section. This vertical extension creates additional boundary area between the first and second electrically-conductive type semiconductor regions without increasing the planar footprint. The trench structure transforms a two-dimensional interface into a three-dimensional boundary, thereby increasing the saturated charge amount while maintaining a compact device footprint.
Solution Approach 2:
The charge-holding section is segmented by introducing a trench structure that divides the semiconductor layer into distinct regions. The trench section includes a first base and a first semiconductor layer that covers the first base, creating multiple interfaces within the charge-holding section. This segmentation increases the total boundary area between different electrically-conductive type regions, enabling higher charge storage capacity.
2Reliability
If the boundary area between semiconductor regions is increased, then charge transfer capability improves, but manufacturing precision requirements increase
Solution Approach 1:
The trench section is formed as a pre-structured element within the charge-holding section before final device operation. The first base and first semiconductor layer are prepared in advance during the manufacturing process, establishing the boundary structure that will facilitate charge transfer. This preliminary formation of the trench structure allows for controlled creation of the extended boundary area, managing manufacturing precision requirements through planned fabrication steps.
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 increases the saturated charge amount, improving the dynamic range and reliability of the imaging device by facilitating smoother charge transfer and storage, thereby enhancing imaging performance.
Implementation Method 1
a photoelectric conversion section of a second electrically-conductive type embedded in the semiconductor substrate and configured to generate charges corresponding to an amount of light reception by means of photoelectric conversion
Data Source
AI summary
An imaging device including a charge-holding section having a larger saturated charge amount is provided. The imaging device includes a first electrically-conductive type semiconductor substrate, a second electrically-conductive type photoelectric conversion section, a second electrically-conductive type charge-holding section, a transfer section, and a trench section. The semiconductor substrate includes a first surface and a second surface opposite thereto. The photoelectric conversion section, embedded in the semiconductor substrate, generates charges corresponding to a light reception amount by photoelectric conversion. The charge-holding section, embedded in the semiconductor substrate, holds the charges generated in the photoelectric conversion section. The transfer section transfers charges from the photoelectric conversion section to a transfer destination. The trench section extends in a thickness direction from the first surface toward the second surface in the charge-holding section. The trench section includes a first base and a first electrically-conductive type first semiconductor layer provided to cover the first base.