SiC Schottky Edge Layout for Low-Leakage Power Converters
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Solution Overview
Problem
The density of Schottky barrier diodes (SBDs) around the edge of the active region in silicon carbide semiconductor devices is often lower than inside the active region, leading to increased forward voltage and reduced reliability due to stacking faults, and widening them to increase density can result in higher leakage current in the reverse blocking state.
Innovation Solution
A silicon carbide semiconductor device design featuring striped first separation regions bent at a right angle around the edge of the active region, with a constant width, and a p-type well region surrounding the active region, allowing for a higher density of SBDs without increasing leakage current, enabling a unipolar current of higher density to flow through the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the width of SBDs is increased to increase the density of SBDs around the edge of the active region, then the density of SBDs is improved, but the leakage current in the reverse blocking state increases
Solution Approach 1:
The first separation region is configured with a bent tip instead of a straight edge, creating a curved geometry that increases the effective width and density of SBDs at the edge of the active region without simply widening the entire structure. This curvature allows the SBD density to be increased while maintaining control over the electric field distribution to prevent excessive leakage current.
Solution Approach 2:
The invention applies different geometric characteristics to different parts of the separation region: the main body maintains a constant width for stability, while the tip is bent to locally increase the SBD density at the critical edge region. This localized modification targets the specific problem area without unnecessarily increasing the overall device size or affecting other regions.
2Reliability
If the density of SBDs around the edge of the active region is increased, then the reliability is improved, but the forward voltage increases due to stacking fault expansion
Solution Approach 1:
The bent tip configuration of the first separation region increases SBD density at the edge without requiring excessive widening that would create large areas prone to stacking faults. The curved geometry concentrates the density increase in a controlled manner, improving reliability by suppressing stacking fault expansion while maintaining acceptable forward voltage levels.
Solution Approach 2:
Instead of uniformly increasing SBD density across the entire active region, the invention applies the density increase partially and selectively at the edge region through the bent tip. This partial action targets the specific area where body diode operation is most problematic, improving reliability without unnecessarily increasing forward voltage across the whole device.
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 enhances the reliability of silicon carbide semiconductor devices by maintaining low leakage current in the reverse blocking state while increasing the surface density of SBDs around the active region, allowing for higher unipolar current density flow without triggering body diodes at the edge.
Implementation Method 1
Schottky barrier diodes (SBD) that are unipolar diodes
Implementation Method 2
a first separation region of the first conductivity type that is a stripe, formed in a constant width, and formed in the well region in the plan view, the first separation region including a tip formed in a bent shape
Data Source
AI summary
A silicon carbide semiconductor device according to the present disclosure includes: a drift layer of a first conductivity type on a semiconductor substrate of the first conductivity type; a well region of a second conductivity type in a surface layer of the drift layer; a source region of the first conductivity type; a first separation regions of the first conductivity type that is a stripe, formed in a constant width, and formed in the well region in a plan view, the first separation region including a bent tip; a second separation region of the first conductivity type that is formed adjacent to the well region; a gate insulating film; a gate electrode; a Schottky electrode on the first separation region; and a source electrode.