SiC Ohmic Electrode Carbon Cluster Distribution Control
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Solution Overview
Problem
Current laser annealing methods for forming ohmic electrodes on silicon carbide semiconductor devices result in increased contact resistance due to undiffused carbon clusters at the interface, making it difficult to achieve low and reproducible resistance.
Innovation Solution
A silicon carbide semiconductor device design where the electrode layer contains carbon clusters distributed within a specific area ratio of 10-40% in the interface region up to 300 nm from the interface, formed by pulsed laser annealing, ensuring diffused carbon clusters without aggregation, and including nickel and silicon to reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If laser annealing is used to form ohmic electrodes on silicon carbide semiconductor devices, then the electrode formation process is simplified, but carbon clusters aggregate at the interface causing increased contact resistance
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of carbon clusters within the electrode layer. Specifically, the carbon cluster concentration is controlled to be higher in the lower portion (near the SiC interface) and lower in the upper portion, achieving different local properties: sufficient carbon for ohmic contact at the interface while preventing excessive aggregation that would increase resistance
Solution Approach 2:
The patent changes the physical and chemical parameters of the electrode layer by controlling carbon cluster size (0.5-5 nm diameter) and concentration distribution. The carbon cluster concentration is specifically controlled at 10-40% in the lower portion and 1-20% in the upper portion, with these parameter ranges optimized to achieve low contact resistance while preventing harmful aggregation
2Reliability
If the electrode layer contains high carbon concentration, then ohmic contact is improved, but carbon clusters aggregate reducing electrical performance
Solution Approach 1:
The patent implements local quality by establishing different carbon cluster concentration requirements for different regions of the electrode layer. The lower portion (near SiC interface) requires 10-40% carbon cluster concentration for optimal ohmic contact, while the upper portion requires only 1-20%, creating a gradient distribution that satisfies different functional requirements locally
Solution Approach 2:
The patent segments the electrode layer into two distinct regions for independent carbon cluster concentration control: a lower portion adjacent to the SiC substrate and an upper portion farther from the interface. This segmentation allows independent optimization of carbon content in each region, achieving overall performance optimization through localized composition control
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 design achieves low contact resistance and secure ohmic contact between the silicon carbide semiconductor layer and the electrode layer by controlling the distribution of carbon clusters, preventing aggregation and excessive diffusion, thereby optimizing electrical performance.
Implementation Method 1
subsequently, pulsed laser annealing is performed on the silicon carbide semiconductor device
Implementation Method 2
carbon (C) in the SiC is diffused in the electrode
Data Source
AI summary
A silicon carbide semiconductor device includes: a silicon carbide semiconductor layer; and an electrode layer in contact with the silicon carbide semiconductor layer. In a case where the electrode layer is equally divided into two in a thickness direction in one cross section of the electrode layer in the thickness direction to obtain a first region facing the silicon carbide semiconductor layer and a second region opposite to the silicon carbide semiconductor layer, an area of a carbon portion containing the carbon in the first region is wider than an area of the carbon portion in the second region. At an interface region located up to 300 nm from an interface between the silicon carbide semiconductor layer and the electrode layer, the carbon portion includes a plurality of portions disposed with a space interposed therebetween, and a ratio of area occupied by the carbon portion is not more than 40%.