Vertical MOSFET Schottky Diode Layout for Lower Reverse Recovery
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Solution Overview
Problem
Power MOSFETs experience significant recovery loss due to minority carriers in the body diode, making it challenging to sufficiently reduce the reverse recovery charge.
Innovation Solution
Incorporating a Schottky barrier diode in a vertical MOSFET configuration, which reduces the amount of minority carriers injected into the drift region during forward operation, thereby minimizing the reverse recovery charge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a body diode is formed in a power MOSFET, then the device can perform reverse conduction, but minority carriers remain in the diode causing significant recovery loss
Solution Approach 1:
The body diode is divided into two separate diodes: a first diode formed in the drift region and a second diode formed in the source region. This segmentation allows each diode to handle specific conduction paths, reducing minority carrier accumulation and recovery loss while maintaining reverse conduction capability.
Solution Approach 2:
A lightly-doped n-type semiconductor region is introduced as an intermediary between the drain and source regions. This intermediate region facilitates carrier transport and reduces minority carrier injection into the drift region, thereby lowering recovery loss during reverse operation.
2Loss of energy
If the amount of minority carriers injected into the drift region is reduced, then reverse recovery charge is reduced, but it is difficult to sufficiently reduce the reverse recovery charge with this method alone
Solution Approach 1:
The body diode is divided into two separate diodes: a first diode formed in the drift region and a second diode formed in the source region. This segmentation allows each diode to handle specific conduction paths, reducing minority carrier accumulation and recovery loss while maintaining reverse conduction capability.
Solution Approach 2:
A lightly-doped n-type semiconductor region is introduced as an intermediary between the drain and source regions. This intermediate region facilitates carrier transport and reduces minority carrier injection into the drift region, thereby lowering recovery loss during reverse operation.
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 implementation of a Schottky barrier diode in the semiconductor device effectively reduces the reverse recovery charge, improving the device's efficiency and reducing recovery losses.
Implementation Method 1
a second conductive portion adjacent to the second semiconductor region along the first surface, the second conductive portion being connected to the first electrode and forming a Schottky junction with the second semiconductor region
Data Source
AI summary
A semiconductor device includes a semiconductor layer having first and second surfaces and including a first semiconductor region of a first type, first and second electrodes, a first insulation region, a first conductive portion electrically connected to the first electrode, a second insulation region, a first control electrode in the second insulation region, a second semiconductor region of the first type between the first and second insulation regions, a second conductive portion adjacent to the second semiconductor region and forming a Schottky junction with the second semiconductor region, a third semiconductor region of a second type on the first semiconductor region, and a fourth semiconductor region of the first type between the third semiconductor region and the first electrode. The third and fourth semiconductor regions are electrically connected to the first electrode.