SiC Drift Region Doping for Precise Impurity Concentration Control
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Solution Overview
Problem
Existing SiC semiconductor devices face challenges in improving electrical characteristics, particularly in the adjustment of impurity concentrations in drift regions, leading to variations in target concentrations and difficulties in controlling impurity introduction during epitaxial growth.
Innovation Solution
The SiC semiconductor device incorporates an n-type or p-type drift region with impurity concentrations adjusted by multiple types of pentavalent or trivalent elements, respectively, to form a pn-junction, allowing for precise control of impurity concentrations through ion implantation methods, reducing concentration variations and enhancing electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If impurity concentration is adjusted during epitaxial growth, then electrical characteristics can be improved, but concentration variations occur and target concentration control becomes difficult
Solution Approach 1:
The drift region is divided into multiple regions with different impurity concentrations. Specifically, a first drift region with a first impurity concentration and a second drift region with a second impurity concentration are formed adjacent to each other in the surface layer portion of the SiC chip. This segmentation allows each region to be optimized for different electrical characteristics while maintaining overall device performance.
Solution Approach 2:
Different impurity concentrations are applied to different spatial locations within the drift region. The first drift region has a first impurity concentration optimized for certain electrical characteristics, while the second drift region has a second impurity concentration optimized for other characteristics. This local quality approach enables precise control of electrical properties in specific areas without affecting the entire drift region uniformly.
2Ease of manufacture
If single type of pentavalent element is used for impurity adjustment, then manufacturing process is simplified, but electrical characteristic optimization is limited
Solution Approach 1:
The patent uses composite doping with multiple types of pentavalent elements (such as phosphorus and nitrogen) to adjust impurity concentrations in the drift region. This composite approach combines the advantages of different elements: phosphorus provides effective n-type doping, while nitrogen contributes to both doping and crystal structure stability. The combination enables better electrical characteristic optimization while maintaining manufacturing feasibility.
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 improved electrical characteristics by reducing impurity concentration variations and allowing for precise adjustment, leading to enhanced performance in SiC semiconductor devices.
Implementation Method 1
an n-type drift region that is formed in a surface layer portion of the main surface and has an impurity concentration adjusted by at least two types of pentavalent elements
Data Source
AI summary
An SiC semiconductor device includes an SiC semiconductor chip that has a main surface, an n-type drift region that is formed in a surface layer portion of the main surface and has an impurity concentration adjusted by at least two types of pentavalent elements, and a p-type impurity region that is formed inside the drift region such as to form a pn-junction portion with the drift region.