Semiconductor Device Lateral Junction Extension Rings
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Solution Overview
Problem
Semiconductor devices with wide energy gaps face challenges in electric field crowding at lateral edges, leading to reduced breakdown voltage and increased leakage current at high temperatures, especially in materials like SiC, which limits their operational voltage and temperature capabilities.
Innovation Solution
The use of a combination of semiconductor material rings and semi-insulating material rings surrounding the junction, where the semiconductor material rings are doped to alter conductivity and the semi-insulating rings are used to reduce leakage current, effectively distributing the electric field and maintaining low leakage even at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If extension means are added to distribute electric field laterally, then breakdown voltage is improved, but device complexity increases
Solution Approach 1:
The extension means is segmented into multiple concentric rings (first ring, second ring, third ring) with different doping types and concentrations. Each ring segment handles a portion of the electric field distribution, allowing the system to achieve high breakdown voltage through distributed field management rather than a single complex structure.
Solution Approach 2:
Different regions of the extension means have different local properties: the first ring has first doping type with first concentration, the second ring has second doping type with second concentration, and the third ring has third doping type with third concentration. This local differentiation optimizes electric field distribution at each radial position, achieving superior breakdown characteristics.
2Strength
If doping concentration is increased to extend depletion region, then breakdown voltage is improved, but manufacturing precision requirements increase
Solution Approach 1:
The doping profile is segmented into distinct rings with discrete concentration levels rather than requiring a continuously graded profile. This segmentation simplifies manufacturing by allowing separate doping steps for each ring, reducing the precision required compared to achieving a continuous gradient.
Solution Approach 2:
The invention uses discrete changes in doping concentration across different rings rather than continuous variation. The first, second, and third doping concentrations are distinct parameter levels that can be achieved through standard semiconductor doping processes, making manufacturing more feasible while still achieving the desired depletion region extension.
3Reliability
If semi-insulating material is used to reduce leakage current, then reliability is improved, but temperature dependence increases leakage
Solution Approach 1:
The extension means uses a composite doping structure combining multiple doping types (first, second, and third doping types) in concentric rings. This composite approach creates complementary effects where the different doping profiles work together to suppress leakage current while maintaining stability across temperature variations, overcoming the limitations of single-material solutions.
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 solution extends the depletion region laterally, reducing electric field concentrations and maintaining low leakage current at high temperatures, thereby enhancing the breakdown voltage and operational capabilities of semiconductor devices with wide energy gaps.
Implementation Method 1
extension means for extending a termination of said junction and by that distributing the electric field within said first layer laterally with respect to the lateral border of said second layer
Implementation Method 2
The extension of the depletion region under the junction is shown by the dashed line 7
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
A semiconductor device comprises a first layer (1) of a wide band gap semiconductor material doped according to a first conductivity type and a second layer (3) on top thereof designed to form a junction blocking current in the reverse biased state of the device at the interface to said first layer. The device comprises extension means for extending a termination of the junction laterally with respect to the lateral border (6) of the second layer. This extension means comprises a plurality of rings (16-21) in juxtaposition laterally surrounding said junction (15) and being arranged as seen in the lateral direction away from said junction alternatively a ring (16-18) of a semiconductor material of a second conductivity type opposite to that of said first layer and a ring (19-21) of a semi-insulating material.