GAAFET Channel Junction Layout for Higher Breakdown Voltage
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Solution Overview
Problem
Gate-all-around field effect transistors (GAAFETs) face challenges such as short-channel effects and low breakdown voltage, limiting their application in high voltage operations like one-time-programmable (OTP) memory cells.
Innovation Solution
The GAAFET design includes channels with regions of varying equivalent carrier densities, inducing additional junctions to enhance reliability and increase breakdown voltage by distributing electric fields and depletion regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the channel length is decreased to achieve smaller footprint, then the device size is reduced, but short-channel effects increase
Solution Approach 1:
The channel is divided into two regions with different doping concentrations: a first region with higher carrier density and a second region with lower carrier density. This local variation in quality allows the channel to maintain better electrical characteristics despite the reduced overall length, thereby resisting short-channel effects while keeping the device footprint small.
Solution Approach 2:
The channel is segmented into multiple regions with different doping profiles. This segmentation creates additional junctions within the channel that help control the electric field distribution, improving the device's ability to resist short-channel effects without increasing the overall device size.
2Volume of moving object
If the channel length is decreased to achieve smaller footprint, then the device size is reduced, but breakdown voltage decreases
Solution Approach 1:
By creating regions with different doping concentrations along the channel, the electric field is redistributed locally. The junction between the first and second regions helps to weaken the electric field at the drain, thereby increasing the breakdown voltage while maintaining the reduced device footprint.
Solution Approach 2:
The junction between the first and second channel regions acts as an intermediary that modifies the electric field distribution. This intermediate structure helps to distribute the electric field more evenly, preventing excessive field concentration at the drain and thus increasing breakdown voltage in a compact device.
3Reliability
If additional junctions are induced in the channel to improve reliability, then short-channel effects resistance increases, but device complexity increases
Solution Approach 1:
The complexity is managed by implementing the doping variation only in specific regions of the channel rather than throughout the entire device. This localized approach to creating junctions improves reliability against short-channel effects while minimizing the overall structural complexity and fabrication difficulty.
Data Source
AI summary
A gate-all-around field effect transistor (GAAFET) includes a substrate, a source structure, a drain structure, at least one channel, and a gate structure. The source structure and the drain structure are disposed on the substrate. Each of the at least one channel is extending between the source structure and the drain structure. The gate structure is disposed between the source structure and the drain structure, and surrounding the at least one channel. When the GAAFET is operated in a saturation state, each of the at least one channel comprises a first region, a second region, and an electrical junction between the first region and the second region. The first region is adjacent to the drain structure, and the second region is adjacent to the first region.