Buffer Region Doping Profile for Turn-Off Overshoot Suppression
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Solution Overview
Problem
Semiconductor devices with buffer regions having doping concentration peaks face challenges in preventing voltage overshoot during turn-off due to the expansion of space charge regions reaching high concentration peaks, leading to inefficiencies in voltage and current characteristics.
Innovation Solution
The semiconductor device incorporates a buffer region with multiple doping concentration peaks and sub-peaks, strategically designed to slow down the expansion of the space charge region by adjusting the peak widths and concentrations, thereby suppressing voltage overshoot and enhancing switching speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a buffer region with doping concentration peaks is used, then voltage overshoot is suppressed, but switching speed decreases
Solution Approach 1:
The buffer region is divided into multiple segments with different doping concentration peaks arranged at different depths. Each peak has a specific concentration and depth position that segments the space charge region expansion process, allowing controlled suppression of voltage overshoot while maintaining switching performance
Solution Approach 2:
Different regions of the buffer region are assigned different doping concentrations and depths to create localized properties. The first doping concentration peak is positioned at a specific depth with a specific concentration, while the second peak is positioned deeper with different concentration characteristics, optimizing both voltage suppression and switching speed in different local regions
2Reliability
If doping concentration peaks are increased to suppress voltage overshoot, then voltage control improves, but electric field concentration increases causing harmful effects
Solution Approach 1:
The doping concentration and depth parameters are optimized to balance voltage control and electric field distribution. The first doping concentration peak is set at 1×10^16 to 1×10^18 atoms/cm³ at a depth of 5 to 15 μm, while the second peak is set at 1×10^15 to 1×10^17 atoms/cm³ at a depth of 15 to 25 μm, creating a gradient that controls voltage without excessive electric field concentration
Solution Approach 2:
The buffer region acts as an intermediary between the drift region and the contact region, mediating the electric field distribution. The multiple doping peaks create intermediate zones that gradually manage the electric field transition, preventing sudden concentration and reducing harmful effects while maintaining voltage control
Data Source
AI summary
Provided is a semiconductor device including a buffer region of a first conductivity type, which is provided between a lower surface of a semiconductor substrate and a drift region, has three or more doping concentration peaks in a depth direction of the semiconductor substrate, and has a higher concentration than the drift region, in which the three or more doping concentration peaks include a deepest peak farthest from the lower surface of the semiconductor substrate and a second peak second closest to the lower surface of the semiconductor substrate, and a peak width of the second peak is 2 times or more of a peak width of the deepest peak in the depth direction.