Stepped JBS Schottky Diode Structure for Lower Conduction Loss
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Solution Overview
Problem
Conduction loss in Schottky barrier diodes (SBDs) with a junction barrier Schottky (JBS) structure is higher due to the reduced area of the Schottky junction caused by the presence of both Schottky and pn junctions.
Innovation Solution
The semiconductor device incorporates a semiconductor substrate with Schottky junction regions and pn junction regions, where the substrate has first and second trenches forming steps at the surface, increasing the area of contact between the n-type drift region and the Schottky electrode, and between the p+-type regions and the Schottky electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a JBS structure with both Schottky junction and pn junction is adopted, then the tolerance against large currents is improved, but the conduction loss increases due to reduced Schottky junction area
Solution Approach 1:
The invention transitions from a two-dimensional planar junction structure to a three-dimensional stepped structure by forming first and second trenches at different depths. This dimensional change allows the Schottky electrode to contact the n-type drift region at multiple height levels, effectively increasing the Schottky junction area without compromising the pn junction functionality for surge current protection.
Solution Approach 2:
The invention segments the Schottky junction area into multiple stepped regions at different heights. By dividing the contact area into first Schottky junction area (at higher level) and second Schottky junction area (at lower level), the total effective area is increased, reducing conduction loss while maintaining the protective function of pn junctions.
2Loss of energy
If the Schottky junction area is increased to reduce conduction loss, then the internal resistance decreases, but the structure complexity increases due to additional trenches and steps
Solution Approach 1:
The invention merges the formation of first and second trenches into a unified stepped structure that serves dual purposes: increasing Schottky junction area for reduced conduction loss and providing step recovery characteristics for surge protection. The Schottky electrode is designed to contact regions at different heights, combining multiple functions into a single integrated structure.
Solution Approach 2:
The invention applies different structural characteristics to different regions: the first trench region provides higher-level Schottky contact for low-resistance path, while the second trench region provides lower-level contact for step recovery effect. Each region is optimized for its specific function, achieving local quality enhancement that resolves the overall contradiction.
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 increased area of contact reduces the internal resistance of the SBDs, thereby decreasing conduction loss, and enhances the tolerance against large currents by increasing the allowable current of the pn junction diodes.
Implementation Method 1
a first electrode forming a Schottky junction with the first-conductivity-type region
Implementation Method 2
a pn junction between the second-conductivity-type region and the first-conductivity-type region
Data Source
AI summary
A semiconductor device, including: a semiconductor substrate including a first-conductivity-type region at a first main surface; a second-conductivity-type region selectively provided at the first main surface and extending in a first direction parallel to the first main surface; a first electrode provided at the first main surface, forming a Schottky junction with the first-conductivity-type region and being in contact with the second-conductivity-type region; and a second electrode provided on a second main surface. The first-conductivity-type region and the second-conductivity-type region includes a plurality of upper surface portions that are aligned in both the first direction and a second direction parallel to the first main surface and perpendicular to the first direction. Each of the upper surface portions forms a first step with another upper surface portion adjacent thereto in the second direction, and forms a second or third step with another upper surface portion adjacent thereto in the first direction.