SiC MOSFET Gate Insulator Defect Reduction via Nitrogen Interface Termination
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Solution Overview
Problem
Silicon carbide (SiC) semiconductor devices, such as MOSFETs, face issues with decreased carrier mobility and threshold voltage fluctuations due to carbon vacancies and defects in the gate insulating layer, which affect the reliability and performance of high-temperature operations.
Innovation Solution
A method for manufacturing SiC semiconductor devices involving ion implantation of aluminum and carbon, followed by heat treatments and hydrogen etching to reduce carbon vacancies, and forming a nitrogen-rich interface termination region to terminate dangling bonds and reduce defects in the gate insulating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If silicon carbide is used to manufacture semiconductor devices, then high-temperature operation capability and low loss are improved, but carrier mobility decreases and threshold voltage fluctuates
Solution Approach 1:
The patent applies local quality by creating a nitrogen-rich interface termination region specifically at the silicon carbide layer interface with the gate insulating layer. This localized nitrogen enrichment (concentration of 1×10^20 to 1×10^22 atoms/cm³) terminates dangling bonds only where needed at the interface, improving carrier mobility and threshold voltage stability without affecting the bulk silicon carbide properties that enable high-temperature operation.
Solution Approach 2:
The patent employs preliminary action by performing nitrogen ion implantation into the silicon carbide layer before forming the gate insulating layer. This advance nitrogen enrichment prepares the interface region to minimize defects and dangling bonds before the gate insulating layer is deposited, thereby preventing threshold voltage fluctuations and maintaining carrier mobility from the outset of device operation.
2Reliability
If ion implantation and heat treatment are performed to reduce carbon vacancies, then carrier mobility is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent merges multiple functions into a single nitrogen ion implantation step. This single process simultaneously: (1) enriches the interface region with nitrogen to terminate dangling bonds, (2) reduces carbon vacancies through the ion implantation damage and subsequent annealing, and (3) prepares the interface for gate insulating layer formation. This consolidation improves carrier mobility while minimizing manufacturing process 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
This approach effectively suppresses the decrease in carrier mobility and stabilizes the threshold voltage, enhancing the performance and reliability of SiC semiconductor devices for high-temperature applications by reducing carbon vacancies and defects in the gate insulating layer.
Implementation Method 1
performing first ion implantation of implanting aluminum (Al) into a silicon carbide layer
Implementation Method 2
performing second ion implantation of implanting carbon (C) into the silicon carbide layer
Implementation Method 3
performing a first heat treatment of 1600° C. or more
Implementation Method 4
performing an oxidation treatment of oxidizing the silicon carbide layer
Implementation Method 5
performing an etching process of etching the silicon carbide layer in an atmosphere containing a hydrogen gas
Data Source
AI summary
A method for manufacturing a semiconductor device of an embodiment includes performing first ion implantation of implanting aluminum (Al) into a silicon carbide layer in a first projected range and a first dose amount, performing second ion implantation of implanting carbon (C) into the silicon carbide layer in a second projected range and a second dose amount which is a dose amount equal to or more than 10 times the first dose amount, performing a first heat treatment of 1600° C. or more, performing an oxidation treatment of oxidizing the silicon carbide layer, performing an etching process of etching the silicon carbide layer in an atmosphere containing a hydrogen gas, forming a silicon oxide film on the silicon carbide layer, and forming a gate electrode on the silicon oxide film.