Two-Phase CCD Electrodes in T-Shaped Grooves
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Solution Overview
Problem
Conventional two-phase charge-coupled devices (CCDs) are more difficult to manufacture and have lower sensitivity due to the complexity of electrode switching and light absorption by polysilicon transfer control electrodes, which limits charge storage capacity and increases bulk.
Innovation Solution
A two-phase CCD structure with electrodes formed in T-shaped grooves, interconnected within columns, and a doped semiconductor layer configuration that avoids direct interfaces between charge storage regions and oxide layers, allowing for improved charge storage and reduced bulk, while maintaining high sensitivity by positioning electrodes vertically within the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional two-phase CCD structure with polysilicon transfer control electrodes is used, then charge transfer function is achieved, but light absorption by electrodes reduces sensitivity
Solution Approach 1:
The patent extracts the harmful function of polysilicon transfer control electrodes that absorb light and reduces their presence in the light path. By positioning electrodes vertically within the substrate and forming them in T-shaped grooves, the design minimizes their interaction with incident light, thereby eliminating the harmful light absorption effect while preserving the charge transfer function.
Solution Approach 2:
The patent transitions from conventional planar electrode arrangements to a vertical three-dimensional configuration. Electrodes are positioned vertically within the substrate thickness rather than lying flat on the surface, changing the spatial dimension of electrode placement. This vertical positioning removes electrodes from the primary light path, eliminating light absorption while maintaining electrical functionality for charge transfer.
2Reliability
If conventional electrode switching mechanism is used, then charge transfer is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent merges multiple electrode functions into a unified vertical electrode structure. By forming all transfer control electrodes as vertical elements within T-shaped grooves and interconnecting them within columns, the design simplifies the manufacturing process. This unified structure eliminates the need for complex multi-layer electrode patterns and reduces the number of separate fabrication steps required, thereby decreasing manufacturing complexity while maintaining charge transfer functionality.
3Quantity of substance
If charge storage capacity is increased, then more charges can be stored, but device bulk increases
Solution Approach 1:
The patent utilizes the vertical dimension within the substrate to increase charge storage capacity without expanding the lateral footprint. By positioning electrodes vertically and creating potential wells through vertical electric field control, the design stores charges along the depth of the substrate rather than requiring larger surface area. This three-dimensional charge storage approach increases capacity while maintaining a compact device bulk.
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
The solution simplifies manufacturing, enhances sensitivity by eliminating light absorption by electrodes, and increases charge storage capacity without increasing bulk, allowing for efficient two-phase charge transfer.
Implementation Method 1
Electrodes 9, properly biased, define in each line 5 a succession of potential wells where electric charges can be stored
Implementation Method 2
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-coupled unit formed in a semiconductor substrate and including an array of identical electrodes forming rows and columns, wherein: each electrode extends in a cavity with insulated walls formed of a groove, oriented along a row, dug into the substrate thickness, and including, at one of its ends, a protrusion extending towards at least one adjacent row.