SiC Gate Dielectric Stack Using Single-Crystal AlOX for Low Interface Defects
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Solution Overview
Problem
The existing gate dielectric layers in SiC MOS devices suffer from high interface defect density, leading to reduced channel mobility and forward conduction capability.
Innovation Solution
A composite dielectric layer is formed by simultaneously oxidizing a SiC substrate and a single-crystal AlN layer, resulting in a stacked structure of SiO2 and single-crystal AlOX layers, which improves interface characteristics and reduces interface states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional gate dielectric layer is formed on SiC substrate, then the device can be manufactured, but the interface defect density is high leading to reduced channel mobility and forward conduction capability
Solution Approach 1:
The patent applies composite materials by forming a stacked dielectric structure consisting of SiO2 layer and AlOX layer. The SiO2 layer provides good interface characteristics with SiC, while the AlOX layer contributes high breakdown strength and low leakage current. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both low interface defects and high reliability.
Solution Approach 2:
The patent uses an AlN layer as an intermediary substance that is grown on the SiC substrate before oxidation. This AlN layer serves as a mediator that facilitates the formation of the AlOX layer and improves the overall interface quality between the dielectric stack and the SiC substrate, thereby reducing interface defect density.
2Reliability
If the gate dielectric layer is optimized for low leakage current, then reliability improves, but the breakdown voltage may be compromised
Solution Approach 1:
The stacked SiO2/AlOX dielectric structure resolves this contradiction by assigning different functional roles to each layer. The AlOX layer, with its wide bandgap and high breakdown field, provides the breakdown voltage strength, while the SiO2 layer, formed with excellent interface quality, minimizes leakage current. The combination achieves both low leakage and high breakdown voltage.
Solution Approach 2:
The patent applies local quality by optimizing each layer's properties for its specific function. The SiO2 layer is optimized for low leakage current through excellent interface quality with SiC, while the AlOX layer is optimized for high breakdown voltage. Each layer performs its specialized function, resolving the contradiction between leakage current and breakdown voltage.
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 proposed solution enhances the quality of the gate dielectric layer, reducing leakage current and improving breakdown voltage, thereby increasing the reliability of SiC MOS devices under high-temperature and high-power conditions.
Implementation Method 1
growing a single-crystal AlN layer on the SiC substrate
Implementation Method 2
simultaneously oxidizing the SiC substrate and the single-crystal AlN layer through a thermal oxidation process to form a composite dielectric layer
Implementation Method 3
thermal oxidation process
Data Source
AI summary
Disclosed are a dielectric structure, a semiconductor device structure and manufacturing methods therefor. The manufacturing method for the dielectric structure includes growing a single-crystal AlN layer on the SiC substrate, and then simultaneously oxidizing the SiC substrate and the single-crystal AlN layer to form a composite dielectric layer including a SiO2 layer and a single-crystal AlOX layer. By simultaneously oxidizing the single-crystal AlN layer provided on the surface of the SiC substrate and the SiC substrate, on the one hand, the AlOX layer includes a higher background concentration of nitrogen, so that nitrogen ions diffuse into the SiO2, thereby improving the interface characteristics of the SiC/SiO2; and on the other hand, after oxidation of the single-crystal AlN layer, the single-crystal AlOX layer with wide band gap and high-density may be introduced, so that the single-crystal AlOX has good quality and a high-quality interface with SiO2.