APD Pixel Power Wiring Structure for High-Illuminance Photon Counting
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Solution Overview
Problem
Avalanche photodiode (APD) sensors face challenges due to high wiring density, which leads to issues with stable current supply and efficient photon counting, particularly under high illuminance conditions.
Innovation Solution
A novel wiring configuration is proposed, where multiple wiring layers are used to connect power supply voltage to pixel circuits, allowing for a two-dimensional layout that reduces wiring density and ensures stable current supply by combining wiring layers to reach both ends of the pixel circuit regions, thereby facilitating efficient photon counting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a high wiring density configuration is used in APD sensors, then the number of circuits and power supply lines can be increased, but current supply stability deteriorates and photon counting efficiency decreases
Solution Approach 1:
The patent transitions from planar wiring layout to three-dimensional stacked wiring layers. Multiple wiring layers are stacked vertically to provide separate pathways for power supply lines, signal lines, and ground lines, enabling high wiring density while maintaining current supply stability through spatial separation of electrical paths.
Solution Approach 2:
The wiring structure is segmented into multiple independent wiring layers, each dedicated to specific functions (power supply, signal, ground). This segmentation isolates power supply lines from other circuits, preventing interference and ensuring stable current supply to pixel circuits even as overall wiring density increases.
2Reliability
If wiring layers are increased to reduce wiring density, then current supply stability improves, but device complexity increases
Solution Approach 1:
Each wiring layer is designed with multi-functionality, serving both as electrical conductors and as structural elements of the stacked substrate architecture. The wiring layers are integrated into the overall substrate stacking scheme, where each layer performs multiple functions including power distribution, signal transmission, and mechanical support, thereby reducing the relative complexity increase.
3Productivity
If multiple wiring layers are used to connect power supply voltage to pixel circuits, then photon counting efficiency improves, but manufacturing complexity increases
Solution Approach 1:
The wiring layers are pre-configured and stacked before final assembly, with power supply lines, signal lines, and ground lines already positioned in their respective layers. This preliminary arrangement simplifies the manufacturing process by avoiding complex routing operations after assembly, as the stacked structure provides ready-made electrical pathways from photodiodes to pixel circuits.
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
The proposed wiring configuration enables stable current supply to pixel circuits, even under high illuminance, by reducing the effects of high wiring density and ensuring efficient photon counting in APD sensors.
Implementation Method 1
a reverse bias voltage is applied to the PN junction diode to cause avalanche multiplication of photocharges resulting from a single photon
Implementation Method 2
photocharges resulting from a single photon
Data Source
AI summary
A photoelectric conversion apparatus includes a first substrate and a second substrate. A plurality of wiring layers of a second wiring structure includes a wiring layer where first wiring for supplying a power supply voltage to a plurality of pixel circuits is disposed and an area occupied by the first wiring is the largest among the plurality of wiring layers, and a wiring layer group where the first wiring is disposed, the wiring layer group being located between the wiring layer where the area and a second semiconductor layer. In a plan view, the first wiring is configured to connect both ends of a region in a first direction and both ends of the region in a second direction intersecting the first direction by combination of the wiring layer group, the region including each of the plurality of pixel circuits.