A Real-Time In Situ Wafer Temperature Measurement System Based on Fiber Bragg Grating Array

Temperature is an essential parameter in the silicon-based micro electro mechanical system (MEMS) fabrication process, and the uneven temperature distribution on a wafer surface could significantly impact the whole fabrication process. This research aims to observe the wire bonding system's heating process from 30 degrees C to 110 degrees C. A temperature sensor network consisting of multiple fiber Bragg gratings (FBGs) is proposed for real-time wafer surface temperature monitoring. The temperature points measured by FBG sensors are used to construct the temperature distribution of the entire wafer surface, enabling tracking of the hotspots during the heating processes. Additionally, a comparative analysis of the FBG sensor network's results was conducted using those gathered by infrared thermal imager and thermocouple (TC) sensors. The results indicate the existence of a temperature gradient along the wafer's surface in the radial direction, with a maximum temperature difference of 11.94 degrees C and the temperature distribution taking the shape of approximate concentric circles. The FBG sensor network offers a clear and intuitive illustration of the wafer's surface temperature distribution during heating, providing real-time responses. Therefore, the proposed temperature measurement network based on FBG sensors can effectively monitor the temperature defects on the wafer surface during the MEMS process.