SiC Gate Interface Layer With Low Carbon Charge Trapping
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Solution Overview
Problem
Silicon carbide devices face challenges with charge trapping due to carbon atoms present in the interface layer between the silicon carbide body and the electrical insulator, which affects the electrical parameters and reliability of the device.
Innovation Solution
A method is developed to form a silicon carbide device with an interface layer having a reduced carbon concentration, deposited directly on the silicon carbide surface with a thickness of less than or equal to 15 nm, and an electrical insulator is formed over this interface layer to reduce charge trapping, using materials like silicon nitride, aluminum nitride, or titanium nitride.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an interface layer is formed between the silicon carbide body and the electrical insulator, then the electrical insulation is improved, but carbon atoms in the interface layer cause charge trapping that worsens device reliability
Solution Approach 1:
The patent removes the oxide layer from the silicon carbide surface before depositing the interface layer, extracting the harmful carbon-containing oxide that would otherwise contribute to charge trapping. This cleaning step eliminates the source of carbon contamination while preserving the beneficial interface layer structure for electrical insulation.
Solution Approach 2:
The patent controls the thickness of the interface layer to be between 1 nm and 15 nm, and adjusts deposition parameters to minimize carbon incorporation. By optimizing these parameters, the interface layer provides sufficient electrical insulation while reducing carbon atom concentration to prevent charge trapping.
2Reliability
If the interface layer thickness is increased to improve electrical insulation, then insulation performance is improved, but carbon incorporation increases leading to more charge trapping
Solution Approach 1:
The patent optimizes the interface layer thickness to a specific range (1-15 nm) that provides adequate electrical insulation while minimizing the total quantity of carbon atoms present. This parameter optimization resolves the contradiction by finding the optimal thickness that satisfies both insulation requirements and charge trapping prevention.
Solution Approach 2:
The patent uses physical vapor deposition to create an interface layer that replicates the desired structural properties without incorporating excessive carbon. The deposition process creates a controlled interface structure that achieves insulation functionality with minimal carbon contamination.
3Strength
If an oxide layer is present on the silicon carbide surface, then surface protection is improved, but carbon from the oxide layer causes charge trapping when the electrical insulator is formed
Solution Approach 1:
The patent performs a preliminary cleaning step to remove the oxide layer before forming the electrical insulator. This preliminary action eliminates carbon contamination from the oxide while the subsequently formed interface layer provides the necessary surface protection and insulation functionality.
Solution Approach 2:
The patent extracts and removes the oxide layer from the silicon carbide surface, eliminating the source of carbon that would otherwise be incorporated into the electrical insulator and cause charge trapping. This extraction step prioritizes device reliability over oxide surface protection.
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 approach effectively minimizes charge trapping, enhancing the reliability and performance of silicon carbide devices by reducing carbon incorporation in the interface layer, thereby improving the electrical insulation and operational stability.
Implementation Method 1
depositing an interface layer directly on the silicon carbide surface
Implementation Method 2
an electrical insulator disposed between the interface layer and the gate electrode. The electrical insulator may be configured to electrically insulate the gate electrode from the silicon carbide body
Data Source
AI summary
A method for forming an interface layer on a silicon carbide body comprises removing an oxide layer from a surface of a silicon carbide body to obtain a silicon carbide surface. The silicon carbide body comprises a source region of a first conductivity type and a body region of a second conductivity type. The method further comprises after removing the oxide layer, depositing an interface layer directly on the silicon carbide surface. The interface layer has a thickness of less or equal to 15 nm. The method further comprises forming an electrical insulator over the interface layer, and forming a gate electrode over the electrical insulator.