Low-Coherence Interferometry-Based Non-Contact Temperature Monitoring of a Silicon Wafer and Chamber Parts during Plasma Etching

We performed real-time non-contact monitoring of temperatures of a silicon wafer and chamber parts in plasma etching processes using optical fiber-based low-coherence interferometry. The measurements were performed in dual-frequency capacitively coupled Ar/C 4 F 8 /O 2 plasma processes. The temperature of a 780-μm-thick Si wafer was measured with a deviation of 0.11 K. Comparison between in-situ measurement results of an on-wafer temperature sensor and an optical-fiber type fluorescence temperature sensor confirmed that the low-coherence interferometry had superior performance in monitoring the temperature of the Si wafer in real-time. This method will enable better control of etching performance with improved process reproducibility.