Stacked Light-Receiving Pixel Structure for Low-Capacitance Readout
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Solution Overview
Problem
Existing imaging devices face challenges in achieving high conversion efficiency of electric charge into voltage, which affects the quality of the images captured.
Innovation Solution
The proposed light-receiving device consists of a first substrate with photoelectric conversion sections and an accumulation section, and a second substrate with a readout circuit. These substrates are stacked with a wiring layer that includes vias to electrically couple the accumulation section and the readout circuit, allowing for efficient signal output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional wiring structure is used to electrically couple the accumulation section and readout circuit, then the device complexity is reduced, but the conversion efficiency of electric charge into voltage deteriorates due to increased capacitance
Solution Approach 1:
The patent transitions from a planar wiring structure to a three-dimensional stacked structure with vias penetrating through multiple wiring layers. This dimensional change allows the readout circuit to be positioned on a different substrate layer, reducing the horizontal distance and capacitance between the accumulation section and readout circuit while maintaining electrical coupling.
Solution Approach 2:
The device is divided into multiple functional substrates: a first substrate containing the photoelectric conversion sections and accumulation section, and a second substrate containing the readout circuit. This segmentation allows independent optimization of each substrate's function and reduces parasitic capacitance by separating the charge accumulation and readout functions into different physical locations.
2Productivity
If the accumulation section is electrically coupled to the readout circuit through multiple wiring layers, then the device integration is improved, but the signal dispersion increases and conversion efficiency deteriorates
Solution Approach 1:
The patent introduces a via structure as an intermediary element that penetrates through multiple wiring layers to establish a direct electrical connection between the accumulation section on the first substrate and the readout circuit on the second substrate. This via acts as a low-capacitance transmission path that minimizes signal dispersion while enabling integration across multiple layers.
Solution Approach 2:
By moving the readout circuit to a separate substrate in the vertical dimension, the patent reduces the horizontal trace length through intermediate wiring layers. The via provides a vertical transmission path that is electrically shorter and has lower capacitance compared to routing through multiple planar wiring layers, thereby reducing signal dispersion.
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 reduces the capacitance added to the accumulation section, thereby improving the conversion efficiency of electric charge into voltage, leading to enhanced image quality and reduced signal dispersion.
Implementation Method 1
a first substrate including a plurality of photoelectric conversion sections that photoelectrically converts light and an accumulation section that accumulates electric charge photoelectrically converted by the photoelectric conversion sections
Data Source
AI summary
A light-receiving device according to an embodiment of the present disclosure includes: a first substrate including a plurality of photoelectric conversion sections that photoelectrically converts light and an accumulation section that accumulates electric charge photoelectrically converted by the photoelectric conversion sections; a second substrate stacked on the first substrate and including a readout circuit that outputs a first signal based on the electric charge accumulated in the accumulation section; and a wiring layer including a via that electrically couples the accumulation section and the readout circuit to each other. The first substrate and the second substrate are stacked to allow a first surface of the first substrate on which an element is formed and a second surface of the second substrate on which an element is formed to be opposed to each other. The via penetrates a plurality of layers in the wiring layer.