SiC MOS Interface Nitrogen Profile for Stable Threshold Voltage
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Solution Overview
Problem
Silicon carbide (SiC) semiconductor devices face issues with decreased carrier mobility and threshold voltage changes due to carbon and nitrogen defects in the gate insulating layer, leading to increased leakage current and reduced reliability.
Innovation Solution
A semiconductor device with a silicon carbide layer, a silicon oxide layer, and an interface termination region with a high nitrogen concentration between them, where the nitrogen concentration peaks at 1×10^22 cm^-3 and decreases to 1×10^18 cm^-3 within 1 nm, effectively reducing carbon and nitrogen defects and trap levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gate insulating layer is formed using conventional methods, then the device can be manufactured, but carbon and nitrogen defects occur in the gate insulating layer causing decreased carrier mobility and threshold voltage changes
Solution Approach 1:
The patent removes carbon and nitrogen impurities from the gate insulating layer by controlling the oxidation process to convert these harmful elements into volatile compounds (CO, CO2, N2) that are eliminated during heat treatment, thereby extracting the harmful factors from the system
Solution Approach 2:
The patent changes the chemical composition parameters of the gate insulating layer by controlling the oxidation atmosphere and heat treatment conditions, transforming the layer into a carbon and nitrogen-free silicon oxide layer with improved electrical characteristics
2Reliability
If a gate insulating layer is formed using conventional methods, then the device can be manufactured, but nitrogen defects exist in the gate insulating layer causing threshold voltage changes
Solution Approach 1:
The patent removes nitrogen impurities from the gate insulating layer by controlling the oxidation process to convert nitrogen into N2 gas that is eliminated during heat treatment, thereby extracting the harmful nitrogen defects from the system
Solution Approach 2:
The patent changes the chemical composition parameters by controlling oxidation conditions to achieve a nitrogen-free gate insulating layer, stabilizing the threshold voltage through improved material purity
3Reliability
If a gate insulating layer is formed using conventional methods, then the device can be manufactured, but carbon defects exist in the gate insulating layer causing leakage current increase
Solution Approach 1:
The patent removes carbon impurities from the gate insulating layer by controlling the oxidation process to convert carbon into volatile CO and CO2 compounds that are eliminated during heat treatment, thereby extracting carbon defects that cause leakage current
Solution Approach 2:
The patent changes the chemical composition parameters by controlling oxidation conditions to achieve a carbon-free gate insulating layer, reducing leakage current through improved material purity
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 suppresses the decrease in carrier mobility, changes in threshold voltage, and leakage current, while enhancing the reliability of the gate insulating layer by minimizing carbon and nitrogen defects, thereby improving the overall performance of SiC MOSFETs.
Implementation Method 1
In a first heat treatment, an interface termination region is formed by oxidizing a surface of the silicon carbide layer in an atmosphere containing ammonia gas
Data Source
AI summary
A semiconductor device according to an embodiment includes: a silicon carbide layer; a silicon oxide layer; and a region disposed between the silicon carbide layer and the silicon oxide layer and having a nitrogen concentration equal to or more than 1×1021 cm−3. A nitrogen concentration distribution in the silicon carbide layer, the silicon oxide layer, and the region have a peak in the region, a nitrogen concentration at a first position 1 nm away from the peak to the side of the silicon oxide layer is equal to or less than 1×1018 cm−3 and a carbon concentration at the first position is equal to or less than 1×1018 cm−3, and a nitrogen concentration at a second position 1 nm away from the peak to the side of the silicon carbide layer is equal to or less than 1×1018 cm−3.