Vertical Electrode CCD for Photon Absorption and Charge Storage
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Solution Overview
Problem
Conventional charge-coupled devices (CCDs) face reduced sensitivity due to photons being absorbed by polysilicon transfer control electrodes, and have limited charge storage capacity and bulk issues.
Innovation Solution
The charge transfer electrodes are arranged vertically within the substrate depth, eliminating the need for light to cross control electrodes and increasing charge storage capacity by interconnecting electrodes for efficient four-phase or three-phase signal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polysilicon transfer control electrodes are arranged horizontally above the photoconversion area, then charge transfer control is achieved, but photons are absorbed by the electrodes reducing sensor sensitivity
Solution Approach 1:
The patent transitions from horizontal electrode arrangement to vertical electrode arrangement, changing the spatial dimension of electrode placement. The electrodes extend through the substrate thickness in grooves, allowing light to pass through the photoconversion area without intersecting the electrodes, thereby eliminating photon absorption while maintaining charge transfer control functionality
Solution Approach 2:
Instead of placing electrodes above the photoconversion area as in conventional designs, the patent inverts the arrangement by placing electrodes within grooves formed in the substrate, with electrodes extending vertically through the substrate thickness. This inversion allows light to pass through the photoconversion area unobstructed while electrodes remain positioned to control charge transfer
2Quantity of substance
If electrode surface area is increased to enhance charge storage capacity, then more charges can be stored, but device bulk increases
Solution Approach 1:
The patent utilizes the vertical dimension by extending electrodes through the substrate thickness in grooves, rather than only expanding horizontal surface area. This allows charge storage capacity to be enhanced by increasing electrode length in the vertical direction, thereby increasing capacity without proportionally increasing device bulk
Solution Approach 2:
The electrodes are nested within grooves formed in the substrate, with insulating material filling the grooves. This nesting arrangement allows electrodes to extend vertically through the substrate thickness, maximizing charge storage capacity within the available vertical space without significantly increasing horizontal device footprint
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 enhances sensor sensitivity, maintains low bulk, and increases charge storage capacity while simplifying the formation process and reducing voltage requirements.
Implementation Method 1
electrons resulting from the creation, by absorption of a photon, of an electron-hole pair in the photoconversion area
Data Source
AI summary
A charge transfer device formed in a semiconductor substrate and including an array of electrodes forming rows and columns, wherein: the electrodes extend, in rows, in successive grooves with insulated walls, disposed in the substrate thickness and parallel to the charge transfer direction.