SiC MOSFET Temperature Sensing via Distributed Polysilicon Diodes
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Solution Overview
Problem
Conventional silicon carbide semiconductor devices face challenges in accurately measuring temperature due to non-uniform temperature distribution, especially at high frequencies and large currents, as the temperature sensing portion is typically located at a single point, leading to potential destruction of the device.
Innovation Solution
The semiconductor device incorporates multiple temperature sensing portions with polysilicon diodes embedded in trenches, which interrupt the MOS structure's trench pattern, allowing for widespread temperature measurement and enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single temperature sensing portion is used, then the device structure is simple, but the temperature measurement accuracy deteriorates due to non-uniform temperature distribution
Solution Approach 1:
The temperature sensing function is segmented into multiple independent sensing portions distributed across different regions of the semiconductor chip. Each sensing portion includes a diode structure with anode and cathode electrodes that can independently measure temperature at its location. This segmentation allows the system to capture non-uniform temperature distribution across the chip, thereby improving overall temperature measurement accuracy while maintaining reasonable structural complexity through modular design.
2Measurement precision
If multiple temperature sensing portions are added, then temperature measurement accuracy improves, but the manufacturing process complexity increases
Solution Approach 1:
The manufacturing process merges the formation of multiple temperature sensing portions with the existing MOSFET fabrication steps. The diode structures for temperature sensing are integrated into the same trench isolation regions and use the same doping, oxidation, and deposition processes as the main power device. This merging approach allows multiple temperature sensors to be fabricated simultaneously in a single manufacturing run, improving temperature measurement accuracy without significantly increasing manufacturing process complexity.
3Measurement precision
If temperature sensing portions are added in the active region, then temperature detection coverage improves, but the current carrying capacity may be affected
Solution Approach 1:
The temperature sensing portions are strategically placed in specific locations within the active region where temperature measurement is most critical, rather than uniformly distributing them. The diode structures are formed in trench isolation regions that do not interfere with the main current flow paths of the MOSFETs. This local quality approach ensures adequate temperature detection coverage in hot spots while preserving the current carrying capacity of the power device by avoiding sensing structures in high-current density areas.
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 configuration enables accurate temperature measurement across a wider region of the semiconductor chip, improving the reliability and performance of silicon carbide semiconductor devices by ensuring uniform temperature detection.
Implementation Method 1
The temperature sensing portion 135a has a function of detecting a temperature of the semiconductor chip 160 by using diode temperature characteristics
Data Source
AI summary
A semiconductor device includes a MOS structure part and first to third temperature sensing portions. The MOS structure part has a semiconductor substrate of a first conductivity type, a first semiconductor layer of the first conductivity type, a second semiconductor layer of a second conductivity type, first semiconductor regions of the first conductivity type, trenches, and gate electrodes provided in the trenches via a gate insulating film. The first to the third temperature sensing portions are provided in plural and each includes the semiconductor substrate, the first semiconductor layer, a temperature sensing trench, a first polysilicon layer of the first conductivity type and a second polysilicon layer of the second conductivity type provided in the temperature sensing trench via an insulating film, a cathode electrode connected to the first polysilicon layer, and an anode electrode connected to the second polysilicon layer.