Image Sensor Deep-Node Layout for Lower FD-Wiring Coupling
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Solution Overview
Problem
Current image sensors face challenges in reducing coupling between the floating diffusion area and wiring, which affects efficiency and conversion gain.
Innovation Solution
The image sensor design includes a deep node that penetrates the second substrate, connecting transistors and wires on different sides, thereby shortening the connection length between the floating diffusion area and wiring, and using a manufacturing method that forms this deep node to minimize coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the connection between floating diffusion area and wiring is made shorter to reduce coupling, then conversion gain is improved, but device complexity increases due to the need for deep nodes penetrating through substrates
Solution Approach 1:
The patent transitions from planar wiring connections to three-dimensional deep node connections that penetrate through the substrate. This vertical dimensional change allows the wiring to be positioned closer to the floating diffusion area in the depth direction, reducing coupling capacitance while maintaining lateral layout flexibility. The deep node structure enables direct vertical connections through isolation layers, achieving shorter effective connection length without increasing lateral device footprint.
Solution Approach 2:
The patent introduces deep nodes as intermediary structures that facilitate connections between different substrate levels. These deep nodes act as conductive mediators that bridge the floating diffusion area and the wiring layer through the substrate thickness, enabling direct connections while maintaining electrical isolation from adjacent structures. The intermediary deep nodes resolve the contradiction by providing a dedicated conduction path that minimizes parasitic coupling.
2Manufacturing precision
If deep nodes are formed to penetrate the second substrate for connecting transistors and wires, then coupling between floating diffusion area and wiring is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent divides the connection structure into segmented components: shallow nodes within the first substrate, deep nodes penetrating the second substrate, and wiring layers positioned at different depths. This segmentation allows each component to be optimized independently - the deep nodes are formed only where needed to penetrate the substrate thickness, while other areas maintain conventional planar structures. The segmented approach reduces manufacturing complexity by localizing the complex deep node formation to specific regions.
Solution Approach 2:
The patent implements a nested structure where deep nodes are formed within existing substrate and isolation layer configurations. The deep nodes are nested within the substrate thickness, passing through predefined isolation layers and connecting to wiring that is nested within dedicated wiring regions. This nesting approach allows the complex deep node structure to be integrated into the existing manufacturing flow without requiring complete process redesign.
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 design enhances efficiency by improving conversion gain and reducing coupling between the floating diffusion area and wiring, leading to improved image sensor performance.
Implementation Method 1
The photodiode serves to convert incident light into an electrical signal
Data Source
AI summary
The present disclosure relates to image sensors. An example image sensor includes a first substrate, a transmission transistor, a second substrate, multiple transistors, multiple wires, and a deep node. The first substrate includes a first side, a second side facing the first side, and a photoelectric conversion area. The transmission transistor is disposed on the first side of the first substrate. The second substrate includes a first side and a second side facing each other. The transistors are disposed on the first side of the second substrate and connected with the transmission transistor. The wires are disposed on the second side of the second substrate. The deep node penetrates the second substrate. The first side of the first substrate and the first side of the second substrate face each other. The transistors and one or more wires are connected through the deep node.