SiC Schottky Diode Reflux Current Control via Localized Doping
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Solution Overview
Problem
In semiconductor devices with trench gate type MOSFETs and Schottky barrier diodes, the reliability is compromised due to increased on-resistance and reflux current flow through the body diode when counter electromotive force increases, leading to leakage current and reduced device reliability.
Innovation Solution
The semiconductor device is designed with a Schottky barrier diode region and a body diode region, where the impurity concentration of the second p-type semiconductor region is set lower than the first and third p-type semiconductor regions, allowing increased reflux current through the Schottky barrier diode to prevent flow through the body diode, thereby maintaining device reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Schottky barrier diode is used to conduct reflux current when counter electromotive force is low, then the reflux current flows only through the Schottky barrier diode, but when the counter electromotive force increases, the reflux current also flows through the body diode causing increased on-resistance
Solution Approach 1:
The patent applies local quality by creating a specific p-type semiconductor region with lower impurity concentration than other p-type regions. This localized modification in the body diode region allows the Schottky barrier diode to maintain preferential current conduction even under high counter electromotive force conditions, preventing body diode activation and maintaining low on-resistance.
2Loss of energy
If the body diode is prevented from conducting, then the on-resistance remains low, but the device complexity increases due to multiple p-type semiconductor regions with different impurity concentrations
Solution Approach 1:
The patent utilizes parameter changes by varying the impurity concentration of the p-type semiconductor region. Specifically, one p-type region is designed with lower impurity concentration compared to other p-type regions, which modifies the electrical characteristics to prevent body diode conduction while maintaining the desired current flow path through the Schottky barrier diode.
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 increases the reflux current through the Schottky barrier diode without turning on the body diode, reducing leakage current and on-resistance, thus enhancing the reliability of the semiconductor device.
Implementation Method 1
when the SiC power device (switching element) is turned off to cut off a current flowing through a motor coil, a counter electromotive force is generated in the motor coil by an electromagnetic induction of the motor coil
Implementation Method 2
In the Schottky barrier diode region, the Schottky barrier diode is formed between an n-type drift layer and a metal layer
Data Source
AI summary
In a Schottky barrier diode region, a Schottky barrier diode is formed between an n-type drift layer and a metal layer, and in a body diode region, a p-type semiconductor region, a p-type semiconductor region, and a p-type semiconductor region are formed in order from a main surface side in the drift layer, and a body diode is formed between the p-type semiconductor region and the drift layer. An impurity concentration of the p-type semiconductor region is decreased lower than the impurity concentration of the p-type semiconductor regions, thereby increasing the reflux current flowing through the Schottky barrier diode and preventing the reflux current from flowing through the body diode.