SiC Semiconductor Device Impurity Segmentation
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Solution Overview
Problem
Existing silicon carbide semiconductor devices face challenges in achieving high breakdown voltage due to increased leak current and loss under reverse bias, particularly with Schottky barrier diodes, which require multiple ion implantation processes for forming P-type regions of varying depths and concentrations, leading to localized surge current concentration and inefficiencies.
Innovation Solution
A silicon carbide semiconductor device structure featuring a silicon carbide drift layer with a P-type region formed from a plurality of unit cells, each comprising a first distribution region with a low P-type impurity concentration and a second distribution region with a higher concentration, allowing for a gradual and continuous impurity concentration adjustment with fewer ion implantations, thereby distributing the P-type impurity uniformly and preventing local surge current concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple ion implantation processes are performed to form P-type regions of different depths and concentrations, then the breakdown voltage can be improved, but the manufacturing complexity and production time increase
Solution Approach 1:
The P-type region is segmented into multiple concentration zones (first concentration region and second concentration region) within a single implantation structure. This allows different impurity concentrations to be achieved in different areas without requiring multiple sequential implantation processes, thus reducing manufacturing complexity while maintaining high breakdown voltage
Solution Approach 2:
Different regions of the P-type structure are assigned different impurity concentrations tailored to their specific functional requirements. The first concentration region and second concentration region have optimized local properties that collectively achieve high breakdown voltage without requiring uniform high-concentration implantation throughout the entire structure
2Device complexity
If P-type regions are locally formed to reduce ion implantation processes, then manufacturing complexity decreases, but surge current becomes concentrated and breakdown voltage cannot be achieved
Solution Approach 1:
The structure implements local quality optimization by creating distinct concentration regions within the P-type area. The first concentration region handles surge current distribution while the second concentration region provides field control, ensuring both manufacturability and high breakdown voltage performance
Solution Approach 2:
The P-type region is divided into functional segments with different impurity concentrations. This segmentation allows the structure to handle surge current effectively while maintaining the required breakdown voltage, avoiding the pitfalls of both uniform low-concentration and uniform high-concentration designs
3Reliability
If P-type regions of different concentrations are arranged in a unit of chip, then surge current distribution is improved, but the number of ion implantation processes increases
Solution Approach 1:
The chip structure is segmented into first concentration regions and second concentration regions that work together to distribute surge current effectively. This segmentation achieves improved reliability without requiring multiple separate implantation processes, as the different concentration zones are formed within a single integrated structure
Solution Approach 2:
The impurity concentration parameter is varied spatially within the P-type region to optimize surge current distribution. By controlling the concentration gradient between the first and second concentration regions, the structure achieves improved current handling while maintaining manufacturing efficiency
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 approach enables the achievement of sufficient breakdown voltage with reduced ion implantation processes, improving both forward and reverse characteristics by uniformly carrying surge current and adapting to various substrate shapes, resulting in high-performance silicon carbide semiconductor devices with enhanced surge current capacity.
Implementation Method 1
in order to form the P-type regions of different conditions, ion implantation has to be performed the number of times that satisfies the different conditions
Data Source
AI summary
A silicon carbide semiconductor device of the present invention comprises a silicon carbide drift layer formed on a silicon carbide substrate, a P-type region formed in a surface layer of the silicon carbide drift layer, and a Schottky electrode formed above the silicon carbide drift layer correspondingly to a forming portion of the P-type region. The P-type region is formed of a plurality of unit cells arranged therein. Each of the unit cells has at least a first distribution region in which the P-type impurity is distributed at first concentration and a second distribution region in which the P-type impurity is distributed at second concentration higher than the first concentration. With this structure, it is possible to provide a silicon carbide semiconductor device in which a sufficient breakdown voltage can be achieved with less number of ion implantations.