SiC Super-Junction Diode Resolving Forward Voltage and Breakdown Trade-off
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Solution Overview
Problem
Silicon carbide Schottky barrier diodes face a trade-off between reducing forward voltage and maintaining sufficient withstand voltage, with existing methods either increasing carrier concentration or reducing the thickness of the n-type drift layer, which compromises either the forward voltage or the withstand voltage.
Innovation Solution
A silicon carbide semiconductor device with a super-junction structure, featuring a silicon carbide substrate with n-type and p-type regions forming a pn junction, where the first anode electrode is Schottky-joined to the n-type region and the second anode electrode is ohmically joined to the p-type region, allowing for a depletion layer to extend in both directions, thereby achieving reduced forward voltage while maintaining high withstand voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the carrier concentration of the n-type drift layer is increased to reduce forward voltage, then the forward voltage is reduced, but the withstand voltage is also reduced
Solution Approach 1:
The invention divides the semiconductor device into two separate Schottky barrier diodes: one formed on the n-type drift layer and another on the p-type drift layer. This segmentation allows each diode to be independently optimized - the n-type diode contributes to low forward voltage while the p-type diode maintains high withstand voltage capability, resolving the trade-off between these two parameters.
Solution Approach 2:
The invention uses a composite structure with both n-type and p-type drift layers in the same device. By combining materials with different electrical characteristics (n-type for low resistance, p-type for high breakdown voltage), the device achieves both low forward voltage and high withstand voltage simultaneously, overcoming the limitations of using a single material type.
2Use of energy by moving object
If the thickness of the n-type drift layer is reduced to reduce forward voltage, then the forward voltage is reduced, but the withstand voltage is also reduced
Solution Approach 1:
The invention segments the drift layer function between n-type and p-type regions. The n-type drift layer can be made thinner to reduce forward voltage drop, while the p-type drift layer provides the necessary breakdown voltage capability, thus resolving the contradiction between thickness reduction and voltage withstand capability.
Solution Approach 2:
Different regions of the device are given different local qualities: the n-type drift layer is optimized for low resistance (thinner, higher carrier concentration) while the p-type drift layer is optimized for high breakdown voltage (thicker, appropriate doping). This local optimization allows the overall device to achieve both low forward voltage and high withstand voltage.
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 device achieves a significant reduction in forward voltage while ensuring sufficient withstand voltage, enhancing the diode's performance by optimizing the impurity concentrations and electrode configurations.
Implementation Method 1
The first anode electrode is Schottky-joined, on the first surface, to the n-type region
Implementation Method 2
The second anode electrode is ohmically joined, on the first surface, to the p-type region
Implementation Method 3
allowing for a depletion layer to extend in both directions
Data Source
AI summary
A silicon carbide substrate is provided with a first surface and a second surface opposite the first surface. The silicon carbide substrate includes an n-type region connecting the first surface and the second surface, and a p-type region being in contact with the first surface and connecting the first surface and the second surface. A first anode electrode is Schottky-joined, on the first surface, to the n-type region. A first cathode electrode is ohmically joined, on the second surface, to the n-type region. A second anode electrode is ohmically joined, on the first surface, to the p-type region. A second cathode electrode is Schottky-joined, on the second surface, to the p-type region.