SiC Semiconductor Device P-Type Extension Region Design
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Solution Overview
Problem
Conventional silicon carbide (SiC) semiconductor devices with epitaxial films in the deep layer, connection layer, and guard ring configurations face challenges in achieving the required withstand voltage due to issues with the thickness and width of the connection layers, leading to excessive equipotential line rise and reduced breakdown voltage.
Innovation Solution
The SiC semiconductor device incorporates a structure with a p-type extension region extending from the tip of the connection layer to the guard ring, made of epitaxial film, which reduces the distance between the connection layer and the guard ring, preventing excessive equipotential line rise and maintaining the thickness of the connection layer, thereby ensuring a desired withstand voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the connection portion is formed with a conventional epitaxial film structure, then the manufacturing process is simplified, but the withstand voltage requirement cannot be met due to excessive equipotential line rise
Solution Approach 1:
The connection layer is segmented into multiple regions: a first connection layer region with lower impurity concentration and a second connection layer region with higher impurity concentration. This segmentation allows different portions of the connection layer to serve different functions - the first region maintains thinner profile to reduce equipotential line rise, while the second region provides sufficient thickness for voltage blocking, thus resolving the contradiction between manufacturing simplicity and withstand voltage requirement.
Solution Approach 2:
Different impurity concentrations are applied to different regions of the connection layer. The first connection layer region has a lower impurity concentration to minimize equipotential line rise, while the second connection layer region has a higher impurity concentration to ensure adequate thickness and voltage blocking capability. This local quality variation allows the single epitaxial film structure to simultaneously satisfy both manufacturing ease and reliability requirements.
2Reliability
If the connection layer thickness is increased to improve withstand voltage, then the breakdown voltage improves, but the equipotential line rise becomes excessive reducing effectiveness
Solution Approach 1:
The connection layer is divided into two distinct regions with different thicknesses and impurity concentrations. The first connection layer region is thinner with lower impurity concentration to minimize equipotential line rise, while the second connection layer region is thicker with higher impurity concentration to provide sufficient breakdown voltage. This segmentation resolves the contradiction by allowing each region to optimize for its specific function.
Solution Approach 2:
The impurity concentration parameter is varied across different regions of the connection layer. By changing the impurity concentration from lower in the first region to higher in the second region, the patent achieves different electrical characteristics in different portions of the same layer, enabling simultaneous optimization of equipotential line control 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
This configuration effectively suppresses the formation of regions with large widths and thin connection layers, ensuring a required breakdown voltage is achieved, even when using epitaxial films, by controlling the equipotential line and electric field concentration.
Implementation Method 1
a p-type extension region extending from the tip of the connection layer to the guard ring, made of epitaxial film
Data Source
AI summary
A top end of the p type connection layer is connected to the p type extension region. By forming such a p type extension region, it becomes possible to eliminate a region where an interval becomes large between the p type connection layer and the p type guard ring. Therefore, in the mesa portion, it is possible to prevent the equipotential line from excessively rising up, and it is possible to secure the withstand voltage.