Transistor Body Region Doping for Termination Blocking Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Transistor devices for power applications, particularly superjunction transistors, face challenges in achieving improved termination blocking voltage and ruggedness while maintaining low on-state resistance, as existing edge termination structures are not optimized for high blocking voltage and can be affected by doping concentration fluctuations.
Innovation Solution
The transistor device incorporates a semiconductor body with a higher doping concentration in the active area compared to the edge termination region, along with a superjunction structure and distinct pn junction depths, to enhance termination blocking voltage and threshold voltage without compromising blocking voltage, allowing independent optimization of the termination structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the doping concentration in the body region is increased to improve termination blocking voltage, then the threshold voltage increases, but the on-state resistance increases
Solution Approach 1:
The patent applies local quality by implementing different doping concentrations in different regions: the body region has a first doping concentration optimized for threshold voltage control, while the termination region has a second doping concentration optimized for blocking voltage. This spatial differentiation allows each region to be optimized for its specific function without compromising the other, resolving the contradiction between threshold voltage and on-state resistance.
2Reliability
If the doping concentration in the body region is increased to improve threshold voltage, then the threshold voltage increases, but the AC performance deteriorates
Solution Approach 1:
By implementing different doping concentrations in the body region versus the termination region, the patent enables the body region to provide adequate threshold voltage while the termination region maintains optimized electrical characteristics for AC performance. The localized doping strategy prevents the degradation of AC performance that would result from uniform doping increases.
3Ease of manufacture
If a uniform doping concentration is used throughout the device, then the manufacturing process is simpler, but the termination blocking voltage is insufficient
Solution Approach 1:
The patent implements local quality through region-specific doping concentrations, where the termination region receives a higher doping concentration than the body region. This approach accepts increased manufacturing complexity in exchange for significantly improved termination blocking voltage, which is critical for device reliability in power applications.
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 design achieves improved AC performance and ruggedness by optimizing the termination blocking voltage and threshold voltage, while maintaining low on-state resistance and high blocking capability, through the use of separate doping concentrations in the active and edge termination regions.
Implementation Method 1
implanting dopants of a second conductivity type into the first surface
Implementation Method 2
locally implanting dopants of the first conductivity type into a predefined area of the first surface to form a source region
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
According to an embodiment, a transistor device comprises a semiconductor body comprising a first surface, a second surface opposing the first surface and side faces, an active area and an edge termination region that laterally surrounds the active area a drain region of a first conductivity type at the second surface, a drift region of the first conductivity type on the drain region and a body region of a second conductivity type that opposes the first conductivity type on the drift region. In the active area a source region of the first conductivity type is arranged on the body region. The body region has a doping concentration that is higher in the active area than in the edge termination region.