Semiconductor Device With Buried Diode For Gate Protection
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Solution Overview
Problem
Power transistors with high voltage blocking capabilities face issues due to high electric fields at the pn-junction between the body and drift regions, leading to potential gate dielectric breakdown, and existing body diodes often have lower current ratings than required.
Innovation Solution
A semiconductor device design featuring a vertical transistor with a diode connected in parallel, where the gate electrode is protected by a dielectric insulation and a buried diode region with a complementary doping type, allowing for high current ratings and low losses, and the diode is designed to have a large pn junction area for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high blocking voltages are used to achieve higher voltage blocking capability, then voltage blocking capability is improved, but gate dielectric may breakdown due to high electric fields
Solution Approach 1:
The drift region is divided into two sections: a first drift region section adjacent to the pn junction and a second drift region section distant from the pn junction. This segmentation allows different electric field distributions in different regions, protecting the gate dielectric while maintaining voltage blocking capability.
Solution Approach 2:
The patent applies different doping concentrations to different regions: the first drift region section has a first doping concentration while the second drift region section has a second doping concentration. This local quality variation optimizes the electric field distribution to protect the gate dielectric from breakdown.
2Adaptability or versatility
If the body diode is used to connect in parallel to the load path, then the diode function is provided, but the current rating is lower than desired
Solution Approach 1:
The patent extends the source electrode into the drift region along the vertical dimension, creating an additional current path through the drift region that is independent of the body diode. This dimensional extension significantly increases the current rating while maintaining the diode function.
Solution Approach 2:
The drift region serves multiple functions: it provides voltage blocking capability for the transistor, forms the pn junction for the body diode, and serves as an additional current path when the source electrode is extended into it, thereby increasing the overall current rating.
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 solution effectively protects the gate dielectric from high electric fields and provides a diode with high current ratings and low losses, improving the reliability and efficiency of the semiconductor device, especially when using wide bandgap materials like silicon carbide.
Implementation Method 1
a gate electrode is adjacent the body region and dielectrically insulated from the body region by a gate dielectric
Implementation Method 2
The body diode is formed by a pn junction between the body region and the drift region
Data Source
AI summary
A manufacturing method provides a semiconductor device having a semiconductor body defining a source region, a body region, a drift region and a diode region. The drift region has a first drift region section and a second drift region section. The diode region is buried within the drift region, and has a semiconductor type opposite to the drift region to form a diode. The diode region is separated from the gate electrode by the first drift region section extending from the diode region in a vertical direction. The gate electrode is adjacent the body region and insulated from the body region by a gate dielectric. A source electrode is electrically connected to the source region, the body region and the diode region. A semiconductor region of a doping type opposite to the doping type of the drift region is arranged between the first drift region section and the source electrode.