In-situ Sensor Integration for Real-Time Junction Temperature Monitoring in Power Modules

Online monitoring of junction temperature (Tj) is crucial for optimizing system performance and ensuring the reliability of power modules. However, existing Tj monitoring methods are limited by various factors, including device degradation, lack of universality across different chip types, and the risk of intrusive damage during the measurement process. To address these issues, this study introduces an innovative approach based on the in-situ fabrication of temperature sensors. These sensors are directly integrated between the chip and the upper copper layer of the Direct Bonded Copper (DBC) base. The surface roughness of the copper layer on the DBC is optimized through a polishing process, enhancing the reliability and performance of the sensors. Additionally, a plasma-enhanced chemical vapor deposition (PECVD) technique is used to deposit a silicon nitride (Si3N4) insulating layer, ensuring a strong bond between the copper and Si3N4 layers and significantly reducing the contact thermal resistance. Unlike traditional external sensors, this in-situ integration method eliminates the need for open-case configurations and allows data transmission via bonding wires, making it suitable for various power devices such as Insulated-Gate Bipolar Transistor (IGBT), MOSFET, and Freewheeling Diode (FWD). The approach also circumvents the high bandwidth requirements typical of traditional monitoring techniques, making it suitable for cost-effective online monitoring. Experimental validation demonstrates the steady-state behavior, transient response, and effectiveness of the sensor in real-time monitoring. The device exhibits an ultra-low dynamic response time of 25 ms and a sensitivity of 2770 ppm/°C. Furthermore, the temperature-resistance characteristic curve shows remarkable consistency with results from commercially available sensors. These findings indicate that the in-situ fabricated sensors, combined with the polishing process and PECVD technology, provide a robust and cost-efficient solution for online Tj monitoring, offering significant advantages in terms of system reliability and performance optimization in power modules.