Vertical JFET With Integrated Body Diode for Low-Parasitic Switching
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Solution Overview
Problem
Conventional power electronics, such as MOSFETs and IGBTs, lack a monolithically integrated source-to-drain connected body diode, leading to increased parasitic inductance and resistance, which complicates circuit design and increases costs and board space requirements.
Innovation Solution
The development of novel vertical JFET devices with a monolithically integrated source-to-drain connected body diode, utilizing GaN for the body diode to enable fast switching and low power loss, and optionally fabricating the diode as a Schottky or merged P-i-N Schottky (MPS) diode for low turn-on voltage and high switching speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power electronics (MOSFETs and IGBTs) are used without monolithic integration, then device functionality is achieved, but parasitic inductance and resistance increase
Solution Approach 1:
The patent merges the body diode and transistor into a single monolithic device structure, where the body diode is formed within the same semiconductor substrate as the transistor. This integration eliminates the need for separate discrete diode components and their associated interconnects, thereby reducing parasitic inductance and resistance while improving overall device reliability and performance.
2Adaptability or versatility
If conventional separate diode configuration is used, then circuit functionality is achieved, but circuit design complexity and board space increase
Solution Approach 1:
The body diode is monolithically integrated within the transistor structure, sharing the same semiconductor substrate and fabrication process. This merger eliminates the need for separate discrete diode components and their associated interconnects, thereby reducing parasitic inductance and resistance while improving overall device reliability and performance.
Solution Approach 2:
The integrated body diode serves multiple functions: it provides the necessary freewheeling path for inductive loads, acts as a clamp diode for voltage protection, and eliminates the need for external discrete diodes. This multi-functionality simplifies circuit design and reduces board space requirements while maintaining full circuit versatility.
3Speed
If GaN material is used for the body diode, then switching speed improves, but manufacturing complexity may increase
Solution Approach 1:
The patent utilizes GaN (gallium nitride) material for the body diode, which fundamentally changes the material parameter from conventional silicon. This parameter change enables superior switching speed and lower power loss characteristics. The GaN material allows for higher electron mobility and faster carrier saturation velocity, resulting in significantly improved switching performance while the patent integrates this advanced material into an existing transistor fabrication framework to manage manufacturing complexity.
Data Source
AI summary
Methods and semiconductor devices are provided. A vertical junction field effect transistor (JFET) includes a substrate, an active region having a plurality of semiconductor fins, a source metal layer on an upper surface of the fins, a source metal pad layer coupled to the semiconductor fins through the source metal layer, a gate region surrounding the semiconductor fins, and a body diode surrounding the gate region.