Imaging Element Capacitor Separated from Substrate
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Solution Overview
Problem
In CMOS solid-state imaging elements, the addition of capacitor elements to enhance dynamic range and reduce image distortion leads to a reduction in the photoelectric conversion area, compromising image quality.
Innovation Solution
An imaging element with a photoelectric transducer, a storage unit, and a capacitor separated by an interlayer insulating film, where the transducer and storage unit are formed in the silicon substrate, and a connecting unit connects the storage unit to the capacitor, allowing for dynamic capacitance adjustment without occupying the photoelectric conversion area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If capacitor elements are added to enhance dynamic range and reduce image distortion, then the dynamic range and image quality improve, but the photoelectric conversion area is reduced
Solution Approach 1:
The patent moves the capacitor from the two-dimensional plane of the silicon substrate to the third dimension by forming it in an interlayer insulating film above the substrate. This vertical relocation allows the capacitor to occupy space in a different dimension, thereby preserving the photoelectric conversion area on the substrate while still providing the necessary capacitance for enhanced dynamic range and reduced image distortion.
Solution Approach 2:
The interlayer insulating film serves as an intermediary medium that hosts the capacitor structure. By placing the capacitor in this intermediate layer between the silicon substrate and the surface, the patent enables the capacitor to function without directly occupying or interfering with the photoelectric conversion area on the substrate, thus resolving the area conflict while maintaining electrical functionality through controlled connections.
2Adaptability or versatility
If capacitor elements are added to enhance dynamic range, then the dynamic range improves, but the photoelectric conversion efficiency decreases
Solution Approach 1:
The patent relocates the capacitor to the interlayer insulating film, utilizing the third dimension (vertical space) rather than consuming horizontal photoelectric conversion area. This dimensional separation ensures that the capacitor's presence does not reduce the active photoelectric conversion region, thereby maintaining high photoelectric conversion efficiency while achieving enhanced dynamic range through the additional capacitance.
Solution Approach 2:
The patent extracts the capacitor from the photoelectric conversion region and places it in the interlayer insulating film. This extraction removes the potential source of area conflict and efficiency reduction, allowing the photoelectric conversion process to operate at full efficiency on the substrate while the separated capacitor provides the necessary dynamic range enhancement through its capacitance function.
3Device complexity
If capacitor elements are integrated in the silicon substrate, then the structure is compact, but the photoelectric conversion area is occupied
Solution Approach 1:
The patent resolves the integration conflict by transitioning from planar integration (2D) to vertical integration (3D). The capacitor is formed in the interlayer insulating film above the silicon substrate, utilizing the vertical dimension for capacitance storage. This approach maintains structural integration and compactness while completely preserving the photoelectric conversion area on the substrate, as the capacitor occupies a different spatial dimension.
Solution Approach 2:
The interlayer insulating film acts as an intermediary layer that accommodates the capacitor structure without interfering with the silicon substrate's photoelectric conversion function. This intermediary placement enables structural integration while avoiding area occupation, as the capacitor is embedded in the insulating film that naturally exists between substrate layers, thus maintaining both compactness and full photoelectric conversion area.
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 maintains high photoelectric conversion efficiency while enabling wider dynamic range and reduced image distortion, achieving higher quality images without decreasing the photoelectric conversion area.
Implementation Method 1
photoelectric transducers utilizing a semiconductor pn junction, are used... electric charge generated as a result of performing photoelectric conversion in a PD included in a pixel
Data Source
AI summary
An imaging element includes a plurality of pixels. Each of the plurality of pixels includes the following element. A photoelectric transducer is disposed in each of the plurality of pixels and is configured to generate electric charge corresponding to received light. A storage unit has a predetermined capacitance and is configured to store therein electric charge transferred from the photoelectric transducer. A capacitor is disposed separate from a silicon substrate with an interlayer insulating film therebetween, the photoelectric transducer and the storage unit being formed in the silicon substrate. A connecting unit is disposed separate from the silicon substrate with the interlayer insulating film therebetween and is configured to connect the storage unit and the capacitor.