JFET Current Capability via Local Quality Doping
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Solution Overview
Problem
Junction field effect transistors (JFETs) provide only a small amount of current, requiring increased size to achieve larger currents, which in turn increases costs.
Innovation Solution
A semiconductor structure comprising a semiconductor substrate with multiple doped regions and wells of different conductivity types, forming a PN junction to enhance current flow without increasing size, utilizing ion implantation and doping processes to control dopant concentrations and regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the size of the JFET is increased to provide a large current, then the current capability is improved, but the cost of the elements increases
Solution Approach 1:
The patent applies local quality by creating regions with different dopant concentrations within the JFET structure. Specifically, it forms a first region with a first dopant concentration and a second region with a second dopant concentration that is different from the first. This allows different parts of the device to have optimized electrical properties, enabling high current capability in specific regions without requiring the entire device to be scaled up, thus avoiding increased cost.
Solution Approach 2:
The patent utilizes parameter changes by varying the dopant concentration across different regions of the JFET. By changing the dopant concentration parameter from a uniform structure to a graded structure with at least two distinct concentration regions, the device achieves improved current characteristics without proportional increases in size or cost. The method also involves changing conductivity types between regions to optimize electrical performance.
2Power
If the size of the JFET is increased to provide a large current, then the current capability is improved, but the device dimensions increase
Solution Approach 1:
By implementing local quality through spatially varying dopant concentrations, the patent enables high current capability in specific localized regions rather than requiring uniform scaling of the entire device. The first region with its specific dopant concentration handles high current density, while other regions can be optimized for different functions, maintaining compact overall dimensions.
Solution Approach 2:
The patent applies dimensionality change by introducing vertical variation in dopant concentration through the formation of wells at different depths and regions at different levels within the semiconductor structure. This allows current capability to be enhanced in the vertical dimension through dopant grading rather than increasing horizontal device footprint, effectively utilizing the third dimension to improve performance without increasing planar size.
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 semiconductor structure enables a JFET to provide a large current while maintaining a compact size, with the PN junction being forward turned on to adjust current flow, thus reducing costs and improving performance.
Implementation Method 1
A first well is formed in the semiconductor substrate and has a second conductivity type... The dopant concentration of the first region is higher than the dopant concentration of the second region
Implementation Method 2
utilizing ion implantation and doping processes to control dopant concentrations and regions
Implementation Method 3
forming a PN junction to enhance current flow without increasing size, with the PN junction being forward turned on to adjust current flow
Data Source
AI summary
A semiconductor structure is provided. A semiconductor substrate has a first conductivity type. A first well is formed in the semiconductor substrate and has a second conductivity type. A first well includes a first region and a second region. The dopant concentration of the first region is higher than the dopant concentration of the second region. A second well has the first conductivity type and is formed in the first region. A first doped region is formed in the first region and has the second conductivity type different than the first conductivity type. The second doped region has the first conductivity type and is formed in the second well. A third doped region has the first conductivity type and is formed in the second region. A fourth doped region has the second conductivity type and is formed in the first region.