SiPM Pixel Trench Layout for Integrated Quenching and Fill Factor
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Solution Overview
Problem
Silicon photomultiplier (SiPM) devices in automotive three-dimensional range imaging systems face limitations in photosensitive area and high process costs due to the need for integrated resistors and capacitors, which occupy additional chip area and increase complexity and cost.
Innovation Solution
The integration of deep trench isolation structures as both quench resistors and capacitors on the same chip, utilizing conductive and dielectric layers to enhance photon conversion efficiency without expanding the chip area, and simplifying the fabrication process by reducing the number of masks required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If integrated resistors and capacitors are used in SiPM devices, then the quenching and timing functions are achieved, but the photosensitive area is limited and process cost increases
Solution Approach 1:
The patent merges the resistor and capacitor functions into the deep trench isolation structure itself. The deep trench isolation structure serves dual purposes: providing electrical isolation between pixels and functioning as the quenching resistor and capacitor for the SPAD. This eliminates the need for separate integrated resistors and capacitors, thereby maximizing the photosensitive area while maintaining quenching functionality.
Solution Approach 2:
The deep trench isolation structure is designed to perform multiple functions simultaneously: pixel isolation, quenching resistance, and quenching capacitance. By making the isolation structure multi-functional, the patent eliminates dedicated components for quenching, thus increasing the photosensitive area without compromising the quenching function.
2Reliability
If integrated resistors and capacitors are used in SiPM devices, then the quenching and timing functions are achieved, but the process cost increases
Solution Approach 1:
The patent combines the quenching resistor and capacitor functions with the deep trench isolation structure fabrication process. The same etching and filling steps used to create the isolation structures are utilized to form the quenching components, eliminating the need for additional integrated resistor and capacitor fabrication steps, thereby reducing process complexity and cost.
Solution Approach 2:
The deep trench isolation structure is designed to perform multiple functions simultaneously: pixel isolation, quenching resistance, and quenching capacitance. By making the isolation structure multi-functional, the patent eliminates dedicated components for quenching, thus increasing the photosensitive area without compromising the quenching function.
3Area of moving object
If deep trench isolation structures are used for both isolation and quenching, then the photosensitive area is increased, but the device complexity increases
Solution Approach 1:
The deep trench isolation structure is designed to perform multiple functions simultaneously: pixel isolation, quenching resistance, and quenching capacitance. By making the isolation structure multi-functional, the patent eliminates dedicated components for quenching, thus increasing the photosensitive area without compromising the quenching function.
4Ease of manufacture
If the number of masks is reduced in fabrication, then the process cost is reduced, but the manufacturing precision may be affected
Solution Approach 1:
The deep trench isolation structure is designed to perform multiple functions simultaneously: pixel isolation, quenching resistance, and quenching capacitance. By making the isolation structure multi-functional, the patent eliminates dedicated components for quenching, thus increasing the photosensitive area without compromising the quenching 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 approach effectively increases the fill factor of the photosensitive area, improves photon conversion efficiency, and reduces process costs by enabling same-chip integration of resistors and capacitors without additional area occupation.
Implementation Method 1
a first deep trench isolation structure located in the base substrate and extending in a first direction; and a second deep trench isolation structure located in the base substrate, electrically insulated from the first deep trench isolation structure
Implementation Method 2
a photosensitive element located in a portion of the base substrate surrounded by the first deep trench isolation structure and the second deep trench isolation structure
Data Source
AI summary
Pixel units, photodetectors and fabrication methods of photodetectors are provided. The Pixel unit include a base substrate; a first deep trench isolation structure located in the base substrate and extending in a first direction; a second deep trench isolation structure located in the base substrate, electrically insulated from the first deep trench isolation structure and extending in a second direction intersecting the first direction, and a photosensitive element located in a portion of the base substrate surrounded by the first deep trench isolation structure and the second deep trench isolation structure and connected in series with the first deep trench isolation structure. The second deep trench isolation structure includes a first conductive layer, a second conductive layer and a dielectric layer between the first conductive layer and the second conductive layer.