Bidirectional Power MOSFET Structure With Cathode Short Region
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Solution Overview
Problem
Conventional bidirectional power MOSFETs are prone to early failure in high voltage-high current conditions due to parasitic bipolar behavior, which can lead to device destruction and reduced energy capability.
Innovation Solution
Incorporating a cathode short region, specifically a P+ region shorted with the source, acts as an absorber of holes to reduce parasitic bipolar gain and enhance energy capability, thereby improving the device's performance and sustaining voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bidirectional power MOSFET structure is used, then device can operate bidirectionally, but parasitic bipolar behavior causes early failure in high voltage-high current conditions
Solution Approach 1:
The patent introduces a P+ cathode short region that converts the harmful parasitic bipolar effect into a beneficial mechanism. The P+ region creates a parasitic bipolar transistor that actively suppresses the harmful parasitic bipolar behavior by providing an alternative current path for holes, thereby reducing the gain of the harmful parasitic transistor and preventing device destruction in high voltage-high current conditions
2Use of energy by moving object
If P+ cathode short region is added to reduce parasitic bipolar gain, then energy capability is enhanced, but device structure becomes more complex
Solution Approach 1:
The patent applies local quality by introducing the P+ cathode short region specifically at the cathode end of the device where it is most needed to suppress parasitic bipolar effects. This localized modification targets the specific problem area without requiring comprehensive structural changes throughout the entire device, thereby enhancing energy capability while minimizing the increase in overall device complexity
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 cathode short region effectively reduces parasitic bipolar gain, delaying device destruction and improving energy capability, allowing for bidirectional operation with increased reliability and voltage handling.
Implementation Method 1
Incorporating a cathode short region, specifically a P+ region shorted with the source, acts as an absorber of holes to reduce parasitic bipolar gain
Data Source
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AI summary
A field effect device includes a semiconductor body separating a source and a drain, both source and drain coupled to the semiconductor body. An insulated control gate is located over the semiconductor body between the source and drain and configured to control a conductive channel extending between the source and drain. First and second doped regions such as highly-doped regions are adjacent to the source. The first or second doped region may be a cathode short region electrically coupled to the source. The cathode short region may be used in a bidirectional power MOSFET.