Stacked Image Sensor Charge Transfer Layout for Faster Readout
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Solution Overview
Problem
Existing laminated solid-state imaging devices face challenges in increasing read-out speed due to the time required to transfer stored charge from the storage electrode to the read-out electrode.
Innovation Solution
A solid-state imaging device is designed with a plurality of photoelectric conversion elements arranged in a matrix, featuring a semiconductor layer with an insulating film and a third electrode within the insulating film, which enhances the transfer of charge from the storage electrode to the read-out electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charge is temporarily moved along the upper surface of the storage electrode in a horizontal direction before flowing into the read-out electrode, then charge storage is achieved, but the transfer time from storage electrode to read-out electrode increases
Solution Approach 1:
The patent segments the charge transfer process into two distinct paths: (1) horizontal movement along the upper surface of the storage electrode for charge storage, and (2) vertical movement through the semiconductor layer directly to the read-out electrode for rapid read-out. This segmentation allows charge to be stored efficiently while enabling fast transfer when needed, resolving the contradiction between storage capability and transfer speed.
Solution Approach 2:
The patent introduces a vertical dimension for charge transfer by positioning the read-out electrode below the storage electrode and enabling charge to move vertically through the semiconductor layer. This dimensional change creates a direct transfer path that bypasses the horizontal movement along the storage electrode surface, significantly reducing transfer time while maintaining storage functionality.
2Reliability
If charge is moved along the upper surface of the storage electrode in a horizontal direction, then charge is stored, but the read-out speed decreases
Solution Approach 1:
The patent divides the charge transfer mechanism into separate storage and read-out functions. The storage function utilizes horizontal charge movement along the storage electrode surface, while the read-out function employs vertical charge movement through the semiconductor layer to the read-out electrode. This functional segmentation enables both reliable charge storage and high-speed read-out to occur independently.
Solution Approach 2:
The patent achieves high-speed read-out by introducing a vertical transfer dimension through the semiconductor layer, which is perpendicular to the horizontal storage path. This dimensional separation allows charge to be read out rapidly via the vertical path without being constrained by the slower horizontal movement required for storage operations.
3Productivity
If a laminated structure with multiple photoelectric conversion elements is used, then photoelectric conversion efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent implements multi-functionality by designing the semiconductor layer to serve dual purposes: (1) as a photoelectric conversion medium that generates charge from incident light, and (2) as a charge transfer medium that conducts charge vertically from the storage electrode to the read-out electrode. This eliminates the need for separate structures for these functions, reducing overall device complexity while maintaining high photoelectric conversion efficiency.
Solution Approach 2:
The patent merges the photoelectric conversion function and the charge transfer function into a single integrated structure. The semiconductor layer simultaneously performs both photoelectric conversion and charge conduction, consolidating multiple functions into one component and thereby simplifying the overall device architecture despite the laminated structure.
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 transfer time of stored charge, thereby increasing the read-out speed of pixel signals from each pixel, and allows for a more efficient storage and read-out process.
Implementation Method 1
a photoelectric conversion film that is disposed between the first electrode and the second electrode
Data Source
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AI summary
A read-out speed is increased. A solid-state imaging device (100) according to an embodiment is a solid-state imaging device including a plurality of photoelectric conversion elements (PD3) arrayed in a matrix, and each of the photoelectric conversion elements includes: a first electrode and a second electrode (112, 117) that are disposed such that principal planes thereof face each other; a photoelectric conversion film (113) that is disposed between the first electrode and the second electrode; a semiconductor layer (114) that is disposed between the photoelectric conversion film and the second electrode and is configured such that a first surface is in contact with the photoelectric conversion film and at least a portion of a second surface on a side opposite to the first surface is in contact with the second electrode; an insulating film (316) that is disposed within the semiconductor layer; and a third electrode (115) that is disposed within the insulating film.