Semiconductor Buffer Region Doping for Gate Voltage Stability
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Solution Overview
Problem
Existing semiconductor devices face challenges in relaxing electric field concentration on the buffer region, which can lead to oscillations in the gate voltage during turn-off.
Innovation Solution
The semiconductor device incorporates a buffer region with three or more concentration peaks in the depth direction, including a shallowest peak closest to the lower surface and a high concentration peak, along with one or more low concentration peaks, to distribute the doping concentration effectively and reduce electric field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional buffer region structure is used, then the device structure is simple, but the electric field concentration on the buffer region cannot be relaxed, leading to gate voltage oscillations
Solution Approach 1:
The buffer region is divided into multiple concentration zones with different doping levels (first concentration region, second concentration region, third concentration region) instead of using a uniform structure. This segmentation allows the electric field to be distributed more evenly across the buffer region, preventing concentration at any single point and thereby suppressing gate voltage oscillations during turn-off.
Solution Approach 2:
Different regions within the buffer are assigned different doping concentrations tailored to their specific functional requirements. The first concentration region (higher doping) is positioned to handle specific electric field conditions, while the second and third regions (lower doping) address other areas of electric field concentration. This local optimization of doping quality enables effective electric field relaxation without requiring complete structural redesign.
2Reliability
If the doping concentration in the buffer region is increased to relax electric field concentration, then the electric field distribution improves, but the device structure becomes more complex
Solution Approach 1:
The doping concentration parameter is varied systematically across different regions of the buffer. The first concentration region has a higher doping concentration, while the second and third regions have progressively lower concentrations. This parameter change strategy allows optimization of electric field distribution by creating a gradient that prevents concentration without requiring additional structural elements, thereby managing complexity through parameter optimization rather than structural multiplication.
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 oscillations in the gate voltage and maintains a uniform electric field strength, enhancing the stability and performance of the semiconductor device.
Implementation Method 1
a buffer region of the first conductivity type which is provided between the drift region and a lower surface of the semiconductor substrate, and has three or more concentration peaks higher than a doping concentration of the drift region of the semiconductor substrate in a depth direction
Data Source
AI summary
Provided is a semiconductor device, including: a trench portion which is provided in an upper surface side of a semiconductor substrate, a cathode region of a first conductivity type or a collect region of a second conductivity type which is provided in a lower surface side of the semiconductor substrate, a buffer region of the first conductivity type which is provided between a lower end of the trench portion and the cathode region or the collect region, and has a first peak, a second peak, a third peak and a fourth peak higher than a bulk donor concentration of the semiconductor substrate in a doping concentration distribution in a depth direction.