Trenched SiC Schottky Diode Structure for Leakage-Voltage Tradeoff
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Solution Overview
Problem
SiC Schottky diodes exhibit a trade-off between high reverse leakage current and low forward voltage drop due to high electric fields at the metal-semiconductor interface, which is not effectively addressed by existing technologies.
Innovation Solution
A trenched junction barrier Schottky (JBS) structure is integrated into the SiC diode using trench geometry to lower the electric field at the Schottky barrier junction, incorporating trenched JBS areas, ohmic contacts, and trenched floating guard rings through a simple processing scheme.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If SiC Schottky diodes are used for high-power applications, then operating temperature and frequency are improved, but reverse leakage current increases due to high electric field at the metal-semiconductor interface
Solution Approach 1:
The patent divides the semiconductor surface into multiple discrete trench structures rather than using a continuous planar surface. Each trench acts as an independent field management unit, segmenting the high electric field regions into localized areas surrounded by lower field regions, thereby reducing overall reverse leakage current while maintaining high-power capabilities
Solution Approach 2:
The patent applies different structural characteristics to different regions: the trench regions provide field termination and leakage reduction, while the inter-trench regions maintain conductivity for power handling. This local differentiation allows simultaneous optimization of both power performance and leakage reduction in different spatial zones
2Loss of energy
If higher epitaxial doping level is used, then forward voltage drop is reduced, but reverse leakage current increases due to higher electric field
Solution Approach 1:
The patent changes the geometric parameters of the device structure by introducing trenches with specific dimensions (depth, width, spacing) that modify the electric field distribution. This structural parameter change allows the device to maintain low forward voltage drop through optimized doping while simultaneously reducing reverse leakage current through field management via trench geometry
3Object-generated harmful factors
If trench geometry is introduced to lower electric field, then reverse leakage current is reduced, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into the single trench structure: field termination, leakage current reduction, and mechanical support. By combining these functions into one integrated structural element rather than using separate components, the patent reduces overall device complexity while achieving the desired electrical performance
4Ease of manufacture
If trenched JBS area, ohmic contacts and trenched floating guard rings are integrated, then manufacturing simplicity is improved, but processing precision requirements increase
Solution Approach 1:
The patent performs preliminary actions by pre-defining trench positions and dimensions that serve as reference features for subsequent processing steps. The trench structures are formed first with precise dimensions, then used as alignment references for implanting dopants and forming contacts, thereby simplifying the overall manufacturing process while maintaining high precision through this sequential reference-based approach
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
The trenched structure improves the trade-off between forward voltage drop and reverse leakage current, reducing manufacturing complexity and cost while maintaining high breakdown voltage and low leakage current.
Implementation Method 1
lower the electric field present at the Schottky barrier junction using trench geometry
Implementation Method 2
implanted regions having a second conductivity type in sidewalls of the trench, a second implanted region having the second conductivity type in a bottom of the trench
Data Source
AI summary
A Schottky diode includes a drift layer of a first conductivity type, a trench in the drift layer, first implanted regions having a second conductivity type in sidewalls of the trench, a second implanted region having the second conductivity type in a bottom of the trench, and a metal in the trench. The first implanted regions have a first doping concentration and the second implanted region has a second doping concentration, wherein the first doping concentration is different than the second doping concentration.