Fabrication of Sensor-on-Wafer (SoW) Temperature Monitoring Sensor

Abstract

Monitoring the wafer temperature during etching is the most important step in maintaining the optimized process condition. The change in the wafer temperature in the high-volume manufacturing (HVM) environment can produce unwanted results such as process failure. In this study, a wafer-type temperature sensor with a diameter, thickness, and weight of 300 mm, 1.3 mm, and 207 g, respectively, was fabricated. The fabricated wafer sensor could measure temperature in the wide range of −30 to 140 °C with 73 points and obtain the wafer temperature with a temperature resolution of 0.065 °C. Particularly, it showed stable performance, collecting information steadily and transmitting information to the Front Opening Unified Pod (FOUP) even at temperatures below −30 °C. Additionally, for both the inductively-coupled-plasma (ICP) and capacitively-coupled-plasma etching processes, even under very large plasma power conditions, the wafer sensor exhibited a stable operation without deforming or damaging the process chamber. The outermost area had the greatest influence on the current yield and was the area where analysis and diagnosis were performed most carefully using the wafer temperature sensor. The temperature distribution of the wafer on the electrostatic chuck (ESC) obtained using the capacitively-coupled-plasma etching equipment ranged between 127.19 and 136.65 °C, and the standard deviation was about 2.34 °C over the entire 300 mm area.