Power Semiconductor Field Stop Region Optimization
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Solution Overview
Problem
Power semiconductor devices face a trade-off between efficiency and robustness due to the thickness of the field stop region affecting switching speed and OFF current, with thin regions improving efficiency but reducing robustness and vice versa.
Innovation Solution
A power semiconductor device with a field stop region formed by alternately arranging regions of strong and weak activation of impurities, allowing for increased hole current during switching on and electron current during switching off, enhancing both efficiency and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the field stop region is made thin to improve switching speed (efficiency), then switching speed is improved, but robustness deteriorates
Solution Approach 1:
The field stop region is divided into multiple sub-regions with different impurity concentrations (first concentration region and second concentration region). This local differentiation allows different portions of the field stop region to serve different functions: one portion optimizes for switching speed while another portion ensures robustness, thereby resolving the contradiction between speed and reliability.
2Reliability
If the field stop region is made thick to improve robustness, then robustness is improved, but switching speed deteriorates
Solution Approach 1:
By creating heterogeneous impurity concentration regions within the field stop region, the invention allows specific local areas to have optimized properties for robustness (higher impurity concentration) while other areas maintain properties favorable for switching speed (lower impurity concentration), thus achieving both goals simultaneously.
Solution Approach 2:
The field stop region is segmented into multiple functional zones with distinct impurity concentrations. This segmentation enables independent optimization of different regions for different performance criteria, allowing the overall structure to achieve both high robustness and high switching speed that would be impossible in a uniform structure.
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 solution enables simultaneous improvement in switching speed and robustness by optimizing the field stop region's structure, ensuring high efficiency and robustness without the traditional trade-offs.
Implementation Method 1
activating the impurities using a first laser annealing process
Implementation Method 2
activating the impurities using a second laser annealing process
Data Source
AI summary
Provided is a semiconductor device. The device comprises an epitaxial layer that constitutes a part of an active cell region and is doped with impurities of a first conductivity type at a first concentration; a field stop region that is located below the epitaxial layer and doped with impurities of a second conductivity type at a second concentration which are then activated; and a collector region that is located below the field stop region 70 and is doped with impurities of a second conductivity type. The field stop region is formed by repeatedly alternately arranging regions in which the activation of the impurities of the first conductivity type is relatively strong and regions in which the activation of the impurities of the first conductivity type is relatively weak.