SiC Trench Gate Buffer Layer to Suppress Carbon Clusters
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Solution Overview
Problem
The formation of carbon clusters in the gate dielectric layer of silicon carbide (SiC) semiconductor devices during oxidation processes leads to non-uniformity and reduced reliability of the gate dielectric layer, affecting the stability and performance of the device.
Innovation Solution
A heterogeneous epitaxial buffer layer is introduced on the inner surface of the trench and the semiconductor layer to form a more reliable gate dielectric layer, suppressing the formation of carbon clusters and enhancing the uniformity and reliability of the gate dielectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a gate dielectric layer is formed on a semiconductor layer by an oxidation process, then the gate dielectric layer can be formed, but Si in SiC is oxidized preferentially and leads to form carbon cluster (C-cluster) in the gate dielectric layer, resulting in lower uniformity and quality of the gate dielectric layer
Solution Approach 1:
A buffer layer is introduced as an intermediary between the SiC semiconductor layer and the gate dielectric layer. This buffer layer prevents direct interaction between the oxidation process and the SiC layer, thereby preventing carbon cluster formation while still allowing the gate dielectric layer to be formed. The buffer layer acts as a mediator that protects the underlying SiC layer during the oxidation process.
Solution Approach 2:
The buffer layer is formed in advance before the gate dielectric layer formation process. By preparing the buffer layer beforehand, the harmful oxidation of SiC is prevented from the outset, ensuring that carbon clusters do not form during subsequent processing steps.
2Reliability
If a gate dielectric layer is formed by oxidation process, then the gate dielectric layer can be created, but the quality and reliability of the gate dielectric layer deteriorate due to carbon cluster formation
Solution Approach 1:
The buffer layer serves as a protective intermediary that isolates the gate dielectric layer formation process from the SiC semiconductor layer. This prevents carbon cluster formation that would otherwise compromise the reliability of the gate dielectric layer, while still allowing the necessary oxidation process to occur.
Solution Approach 2:
The buffer layer is prepared in advance to cushion and protect against the harmful effects of the oxidation process. By having this protective layer in place before the gate dielectric layer formation, the reliability of the final structure is ensured by preventing carbon cluster formation that would occur without the buffer layer.
3Reliability
If a heterogeneous epitaxial buffer layer is introduced between the gate dielectric layer and semiconductor layer, then carbon cluster formation is suppressed and gate dielectric layer reliability is improved, but the device structure becomes more complex
Solution Approach 1:
The device structure is segmented into distinct functional layers, with the buffer layer serving as a separate component between the SiC semiconductor layer and the gate dielectric layer. This segmentation allows each layer to perform its specific function independently, improving reliability while maintaining a clear and organized structure that is easier to manufacture and analyze.
Solution Approach 2:
The buffer layer is formed using composite material structures, specifically a heterogeneous epitaxial layer that combines different material properties. This composite approach allows the buffer layer to provide multiple functions including preventing carbon cluster formation, managing stress, and facilitating the formation of the gate dielectric layer, thereby improving reliability without proportionally increasing 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
The buffer layer improves the stability and reliability of the gate dielectric layer by preventing carbon cluster formation, adjusting electric field distribution, and optimizing channel and current path uniformity, thereby enhancing the overall performance of the semiconductor device.
Implementation Method 1
the buffer layer is a heterogeneous epitaxial layer of the semiconductor layer and covers an inner surface of the trench and the first surface of the semiconductor layer
Implementation Method 2
when a gate dielectric layer is formed on a semiconductor layer by an oxidation process, Si in SiC is oxidized preferentially and leads to form carbon cluster (C-cluster) in the gate dielectric layer
Data Source
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AI summary
A semiconductor device including a semiconductor layer, a trench gate structure (151) and a buffer layer (190) is provided. The semiconductor layer has a first surface and a second surface. The trench gate structure is at least partially located in a trench on the first surface of the semiconductor layer. The semiconductor layer includes a source region (130), a drift region (101) and a body region (110). The buffer layer is a heterogeneous epitaxial layer of the semiconductor layer and covers an inner surface of the trench and the first surface of the semiconductor layer. The buffer layer is located between a gate dielectric layer of the trench gate structure and the semiconductor layer. By serving a heterogeneous epitaxial layer of the semiconductor layer as the buffer layer to form a reliable gate dielectric layer, the formation of carbon cluster in the gate dielectric layer is suppressed, and the reliability of the device is enhanced.