Stacked Solid-State Image Sensor Layout for Higher IR Sensitivity
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Solution Overview
Problem
The existing solid-state imaging devices with multilayer wiring layers between semiconductor layers suffer from reduced photosensitivity due to light shielding, affecting the infrared photoelectric conversion element's performance.
Innovation Solution
A solid-state imaging device configuration that includes a first semiconductor layer with a photoelectric conversion element, a second semiconductor layer with an infrared photoelectric conversion element, and a circuit substrate unit with readout circuits, utilizing contact electrodes to connect charge holding regions and metal pads without diverting conductive paths through the multilayer wiring, thereby reducing light shielding and enhancing photosensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multilayer wiring layer is provided between the first semiconductor layer and the second semiconductor layer, then electrical connection is achieved, but light transmission is shielded and photosensitivity decreases
Solution Approach 1:
The patent moves the electrical connection path from the optical path dimension to a different spatial dimension by using contact electrodes that extend vertically through the first semiconductor layer. This allows wiring to be positioned laterally adjacent to the optical path rather than within it, eliminating light shielding while maintaining electrical connectivity.
Solution Approach 2:
The patent introduces contact electrodes as intermediary structures that perform dual functions: they provide electrical connection between semiconductor layers while simultaneously acting as transparent conduits that do not interfere with light transmission. These contact electrodes serve as mediators between the conflicting requirements of electrical connectivity and optical transparency.
2Ease of operation
If wiring is placed between semiconductor layers for electrical connection, then device functionality is achieved, but light transmission path is blocked
Solution Approach 1:
The patent segments the electrical connection function from the light transmission path by separating wiring into two distinct components: contact electrodes that penetrate the first semiconductor layer vertically, and wiring layers that are positioned laterally. This segmentation allows each component to optimize its function without interfering with the other.
Solution Approach 2:
The patent relocates the wiring from the vertical optical path to lateral dimensions, using contact electrodes to bridge the vertical gap between layers. This dimensional repositioning eliminates the harmful light shielding effect while preserving electrical connectivity.
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 improves the photosensitivity of the infrared photoelectric conversion element by minimizing light shielding, allowing for more efficient light transmission and improved image processing capabilities.
Implementation Method 1
a first photoelectric conversion element that has a first surface and a second surface located opposite to each other and photoelectrically converts light incident from a side of the second surface
Implementation Method 2
a second photoelectric conversion element that photoelectrically converts infrared light incident from a side of the second surface of the first semiconductor layer and transmitted through the first semiconductor layer
Data Source
AI summary
Sensitivity is improved. A solid-state imaging device includes a first semiconductor layer that includes a first photoelectric conversion element that photoelectrically converts light incident from a side of a second surface, and a charge holding region that holds a signal charge photoelectrically converted by the first photoelectric conversion element, a second semiconductor layer that is disposed on a side of a first surface of the first semiconductor layer with a first insulating layer interposed therebetween and includes a second photoelectric conversion element that photoelectrically converts light incident from the side of the second surface of the first semiconductor layer, a circuit substrate unit that is disposed on a side of the second semiconductor layer opposite to a side of the first insulating layer with a second insulating layer interposed therebetween and includes a readout circuit that reads out signal charges photoelectrically converted by the first photoelectric conversion element, an element-side first metal pad that is provided on a side of the second insulating layer opposite to a side of the second semiconductor layer, a circuit-side first metal pad that is provided on the circuit substrate unit and is electrically connected to the readout circuit and bonded to the element-side metal pad, and a first contact electrode that penetrates the first and second insulating layers and electrically connects the charge holding region and the element-side first metal pad.