Embedded Gate Electrode for Image Sensor Transistor Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The degradation of transistor properties due to size reduction in pixel circuits of image sensors, leading to increased random telegraph signal noise, while increasing transistor size to reduce noise results in reduced integration density.
Innovation Solution
Incorporating a region of the driving gate electrode of transistors embedded in the semiconductor substrate, which increases the channel length without enlarging the transistor size, thereby maintaining integration density and preventing property degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size of transistors in pixel circuits is reduced to increase integration density, then integration density is improved, but transistor properties deteriorate and random telegraph signal noise increases
Solution Approach 1:
The gate electrode is extended in the depth direction (vertical dimension) by embedding it into the semiconductor substrate, rather than only expanding in the horizontal plane. This dimensional transition allows increasing channel length without increasing the planar area occupied by the transistor, thus maintaining integration density while improving transistor properties.
Solution Approach 2:
The gate electrode is embedded within the semiconductor substrate, nesting the conductive structure inside the substrate volume. This nesting approach utilizes the vertical space within the substrate to accommodate a longer gate electrode, effectively increasing channel length without consuming additional planar area that would reduce integration density.
2Reliability
If the channel length of transistors is increased to reduce random telegraph signal noise, then transistor properties are improved, but transistor size increases and integration density decreases
Solution Approach 1:
The channel length is extended by utilizing the vertical dimension through substrate embedding, rather than expanding horizontally. This allows the channel length to increase in the depth direction while the planar footprint remains compact, thereby maintaining high integration density despite the increased channel length.
Solution Approach 2:
The gate electrode is divided into multiple segments along the depth direction, with different portions embedded at different depths within the semiconductor substrate. This segmentation allows the channel length to be extended through vertical stacking of gate segments, achieving longer channels without proportional increases in planar 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 approach enhances the reliability and performance of image sensors by maintaining transistor property integrity while allowing for increased channel length without increasing pixel size, thus balancing noise reduction with integration density.
Implementation Method 1
a first photoelectric device configured to receive light and generate an electric charge
Data Source
AI summary
An image sensor includes a semiconductor substrate providing a plurality of pixel regions, a semiconductor photoelectric device disposed in each of the plurality of pixel regions, an organic photoelectric device disposed above the semiconductor photoelectric device, and a pixel circuit disposed below the semiconductor photoelectric device. The pixel circuit includes a plurality of driving transistors configured to generate a pixel voltage signal from an electric charge generated in the semiconductor photoelectric device and the organic photoelectric device. A driving gate electrode of at least one of the plurality of driving transistors has a region embedded in the semiconductor substrate.