SiC TVS Diode Structure for High Voltage Protection
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Solution Overview
Problem
Silicon-based TVS diodes face limitations in high-temperature operation due to high leakage currents and reduced peak power handling, requiring multiple diodes in series for higher breakdown voltages, which increases costs and reduces peak power ratings.
Innovation Solution
The development of Silicon Carbide (SiC) TVS diodes with a P-N diode structure formed within a SiC substrate, featuring an N-type region, a P-type region, and an implanted N-type layer, allowing for higher breakdown voltages and peak power ratings without the need for multiple diodes in series.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If multiple Si TVS diodes are connected in series to achieve higher breakdown voltages, then the breakdown voltage requirement is met, but the peak power rating is reduced and the circuit protection cost increases
Solution Approach 1:
The patent combines multiple P-N junctions in parallel within a single SiC TVS diode structure. The first P-N junction and second P-N junction share a common N-type substrate, creating a unified device that handles high voltage through multiple junctions working together rather than requiring series connections of separate diodes.
Solution Approach 2:
The patent utilizes Silicon Carbide (SiC) material with wide bandgap properties to construct the TVS diode. SiC enables the device to achieve high breakdown voltage (600V or higher) while maintaining high peak power rating, overcoming the limitations of conventional silicon-based TVS diodes that require series connections for high voltage applications.
2Device complexity
If Si TVS diodes are used for high breakdown voltage applications, then the device structure is simple, but multiple diodes in series are required which increases device complexity
Solution Approach 1:
The patent combines multiple P-N junctions in parallel within a single SiC TVS diode structure. The first P-N junction and second P-N junction share a common N-type substrate, creating a unified device that handles high voltage through multiple junctions working together rather than requiring series connections of separate diodes.
3Temperature
If Si TVS diodes operate at high ambient temperatures, then the application requirement is met, but leakage current increases and peak power handling capability is reduced
Solution Approach 1:
The patent changes the material parameter from conventional silicon to Silicon Carbide (SiC), which has a wider bandgap. This material parameter change fundamentally alters the temperature-dependent behavior, enabling low leakage current operation at high temperatures where silicon-based TVS diodes fail.
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
SiC TVS diodes offer improved high-temperature operation with reduced leakage currents and increased peak power handling, enabling higher breakdown voltages up to 600V without the need for series connections, thus enhancing reliability and cost-effectiveness.
Implementation Method 1
an implanted N-type layer, the implanted N-type layer being disposed between the P-type region and the N-type region
Implementation Method 2
A highly doped P-type region may then be formed on the N-type epilayer, where a P/N junction, defining properties of the TVS diode, forms between the N-type epilayer and the P-type region
Implementation Method 3
due to the large bandgap of the SiC (3.26eV vs. 1.1eV for Si), SiC has a lower intrinsic carrier concentration compared to Si
Implementation Method 4
During a voltage transient, the TVS diode operation is triggered to safely discharge the surge current
Data Source
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Figure 5~6
AI summary
A device may include a P-N diode, formed within a SiC substrate. The device may include an N-type region formed within the SiC substrate, a P-type region, formed in an upper portion of the N-type region; and an implanted N-type layer, the implanted N-type layer being disposed between the P-type region and the N-type region.