Power Semiconductor Field Stop Region Dopant Profiling
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Solution Overview
Problem
Power semiconductor devices face challenges in optimizing electrical properties such as conduction and switching losses, short circuit ruggedness, and turn-off softness, particularly in the design of field stop regions which influence the electric field distribution.
Innovation Solution
Incorporating a field stop region with a dopant concentration profile featuring a local maximum and minimum, created by proton implantation, and an emitter adjustment region with higher dopant concentrations, along with a semiconductor substrate with interstitial oxygen concentrations of at least 1E17 cm−3, to enhance the electric field control and device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dopant concentration in the field stop region is increased to improve electric field control, then the short circuit ruggedness is improved, but the conduction losses increase
Solution Approach 1:
The patent applies local quality by creating distinct dopant concentration zones within the field stop region. The first dopant concentration profile has a maximum near the drift region interface for short circuit protection, while the second profile has a maximum near the backside for reducing conduction losses. This spatial differentiation of dopant concentrations allows each zone to optimize for its specific function.
Solution Approach 2:
The patent changes the dopant concentration parameter by introducing a dual-profile structure with different concentration maxima at different positions. The first profile peaks at the drift region interface with concentration Nd1,max, while the second profile peaks near the backside with concentration Nd2,max. This parameter variation enables simultaneous optimization of both short circuit ruggedness and conduction characteristics.
2Loss of energy
If the field stop region dopant concentration is increased to improve blocking state electric field control, then the switching losses are reduced, but the device complexity increases
Solution Approach 1:
The patent implements local quality by positioning the first dopant concentration maximum near the drift region interface to control the electric field during switching transitions. This localized high concentration region provides enhanced field control precisely where needed during the switching event, reducing switching losses without requiring uniform high doping throughout the entire field stop region.
Solution Approach 2:
The patent segments the dopant concentration profile into distinct regions: the first profile with maximum near the drift region interface for switching control, and the second profile with maximum near the backside for conduction optimization. This segmentation allows each segment to be optimized for its specific function, managing overall device complexity through functional decomposition.
3Manufacturing precision
If proton implantation is used to create the field stop region to simplify manufacturing, then the manufacturing precision is improved, but the dopant concentration uniformity decreases
Solution Approach 1:
The patent addresses dopant concentration non-uniformity from proton implantation by introducing a second dopant concentration profile that compensates for the implantation-induced variations. The second profile, with maximum concentration near the backside, is designed to counterbalance the non-uniformity created by the first profile and implantation process, thereby restoring overall compositional stability.
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 improves the electric field distribution and device performance by optimizing the dopant concentration profiles and oxygen content, leading to better conduction, switching, and ruggedness characteristics.
Implementation Method 1
the field stop region has been at least partially created by means of an implantation of protons through the backside
Implementation Method 2
the field stop region comprises, in a cross-section along a vertical direction pointing from the backside to the front side, a dopant concentration profile of dopants of the first conductivity type that exhibits a first local maximum and a first local minimum
Implementation Method 3
an emitter adjustment region of the first conductivity type, the emitter adjustment region being arranged between the field stop region and the backside and having dopants of the first conductivity type at a higher dopant concentration than the field stop region
Data Source
AI summary
A power semiconductor device includes a semiconductor body having front and back sides. The semiconductor body includes drift, field stop and emitter adjustment regions each of a first conductivity type. The field stop region is arranged between the drift region and the backside and has dopants of the first conductivity type at a higher dopant concentration than the drift region. The emitter adjustment region is arranged between the field stop region and the backside and has dopants of the first conductivity type at a higher dopant concentration than the field stop region. The semiconductor body has a concentration of interstitial oxygen of at least 1E17 cm−3. The field stop region includes a region where the dopant concentration is higher than that in the drift region at least by a factor of three. At least 20% of the dopants of the first conductivity type in the region are oxygen-induced thermal donors.