SiC Oxide Thin Film Formation for Low-Defect Gate Interfaces
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Solution Overview
Problem
High-temperature oxidation processes for forming gate oxide films on silicon carbide (SiC) substrates result in carbon-carbon bond formation at the interface, leading to defects such as flat band voltage distortion and carrier mobility degradation, limiting the reliability of SiC high voltage and high current devices.
Innovation Solution
A method involving the deposition of a first thin film on the SiC substrate using radical gases, followed by high-temperature oxidation and annealing, which vaporizes carbon-carbon bonds as CO2, CO, or CH, reducing the carbon residue at the interface and minimizing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature oxidation process is performed to form gate oxide film on SiC substrate, then oxide film is formed, but carbon remains as by-product forming carbon clusters at interface causing defects
Solution Approach 1:
The patent extracts and removes carbon by-products from the oxidation process by introducing a separate carbon removal step using oxygen plasma or chemical treatment, thereby eliminating the harmful carbon clusters at the interface while preserving the oxide film formation
Solution Approach 2:
The patent introduces an intermediary substance or process (such as oxygen plasma or chemical etchants) that selectively reacts with and removes carbon residues without damaging the oxide film or substrate, acting as a mediator between the oxidation process and the final clean interface
2Manufacturing precision
If carbon is removed from SiC bond during oxidation, then oxide film forms, but incomplete bonds and carbon clusters form at interface
Solution Approach 1:
The patent performs preliminary actions before the main oxidation process, such as surface preparation or pre-conditioning of the SiC substrate, to prevent incomplete bonding and carbon cluster formation during the subsequent oxidation and annealing steps
Solution Approach 2:
The patent changes process parameters such as temperature profiles, oxygen partial pressures, or introduction of radical gases during deposition to control the oxidation reaction and prevent carbon cluster formation while maintaining interface quality
3Stability of the object's composition
If annealing is performed after oxidation, then oxide film is stabilized, but defects at interface increase due to carbon clustering
Solution Approach 1:
The patent maintains continuous useful action by combining oxidation and annealing in a controlled sequence or simultaneous process, ensuring that carbon removal continues throughout the thermal treatment to prevent clustering while the oxide film stabilizes
Solution Approach 2:
The patent uses strong oxidizing conditions during or after annealing to ensure complete oxidation of carbon residues, preventing carbon cluster formation even during the thermal stabilization phase of the oxide film
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 reduces interface trap density and enhances the reliability of SiC high voltage devices by minimizing carbon residue, allowing for lower temperature and pressure processing while maintaining device performance.
Implementation Method 1
depositing a first thin film on the SiC substrate by applying a radical gas
Implementation Method 2
forming an oxide film on the first thin film by performing the high-temperature oxidation process
Implementation Method 3
performing annealing on the oxide film... carbon-carbon bonds as CO2, CO, or CH, reducing the carbon residue at the interface
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A
AI summary
An embodiment of the present disclosure provides a method of forming a thin film to minimize an increase in defects at an interface during a high-temperature oxidation process of a SiC substrate, the method including depositing a first thin film on the SiC substrate by applying a radical gas, forming an oxide film on the first thin film by performing the high-temperature oxidation process, and performing annealing on the oxide film.