Dual-Gate JFET Structure for Lower Gate Current
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Solution Overview
Problem
Existing semiconductor devices, such as junction field effect transistors (JFETs), face challenges in reducing gate current and increasing drain current due to impact ionization phenomena at high drain-source voltages, which affect their operational efficiency and reliability.
Innovation Solution
The semiconductor device incorporates a unique structure with a p− type semiconductor substrate and an n− type epitaxial layer, featuring distinct bottom and top gate regions with varying impurity diffusion depths and intervals, which suppresses impact ionization and enhances electron transfer pathways, thereby reducing gate current and increasing drain current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional JFET structure with uniform gate regions is used, then device simplicity is maintained, but impact ionization occurs at high drain-source voltages causing increased gate current and reduced operational efficiency
Solution Approach 1:
The patent applies local quality by creating non-uniform gate regions with different impurity concentrations and depths. Specifically, the gate regions have varying impurity diffusion depths where some portions extend deeper into the semiconductor layer than others, allowing different local areas to have optimized electrical properties for suppressing impact ionization while maintaining overall device functionality
Solution Approach 2:
The patent changes physical parameters of the gate regions, specifically the impurity concentration and diffusion depth. By adjusting these parameters locally across different gate regions, the device achieves optimized electric field distribution that suppresses impact ionization at high voltages, thereby reducing gate current and improving operational efficiency
2Productivity
If gate regions with deeper impurity diffusion are used throughout, then field strength is increased improving electron transfer, but gate current increases due to enhanced impact ionization
Solution Approach 1:
The patent applies local quality by creating non-uniform gate regions with different impurity concentrations and depths. Specifically, the gate regions have varying impurity diffusion depths where some portions extend deeper into the semiconductor layer than others, allowing different local areas to have optimized electrical properties for suppressing impact ionization while maintaining overall device functionality
Solution Approach 2:
The patent uses the varied impurity distribution in gate regions as an intermediary mechanism. The specific pattern of impurity diffusion creates an intermediate electric field structure that mediates between the need for strong field strength (for high drain current) and the need to suppress impact ionization (for low gate current), achieving both objectives simultaneously
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 effectively reduces gate current and increases drain current, improving the operational efficiency and reliability of the semiconductor device by minimizing impact ionization and optimizing field strength, as demonstrated by simulation results showing significant reductions in gate current and increases in drain current at various voltage levels.
Implementation Method 1
face challenges in reducing gate current and increasing drain current due to impact ionization phenomena at high drain-source voltages
Implementation Method 2
optimizing field strength
Data Source
AI summary
A semiconductor device includes a semiconductor layer having a first surface and a second surface at an opposite side thereto, a bottom gate region of a first conductivity type that is formed in the semiconductor layer, and a top gate region of the first conductivity type that is formed in a surface layer portion of the first surface of the semiconductor layer and faces the bottom gate region in a thickness direction of the semiconductor layer, the bottom gate region includes a first bottom gate region at the source region side and a second bottom gate region at the drain region side, and an interval in the thickness direction between the second bottom gate region and the top gate region is greater than an interval in the thickness direction between the first bottom gate region and the top gate region.