This proposal outlines a research program to develop a non-invasive temperature sensor for application in dry etching (plasma etching, reactive ion etching for example) of electronic materials. There is a critical need for such sensors at present since the temperature of the water influences the results of the etching process; etch rate, undercutting, and surface quality. In addition, the photoresist used for masking begins to char at elevated temperatures. Hence, it is important to measure and monitor the wafer temperature at all times. The proposed effort would result in a novel temperature sensor to measure and monitor wafer temperature in dry etching environment. The innovation here is that the proposed technique would enable a non-invasive, contactless and non-destructive method of performing surface temperature measurement in a plasma etching chamber. In contrast, existing techniques are invasive and cumbersome and the need for contacting precludes measuring the process-wafer temperature; instead only the temperature of the cathode or a dummy wafer is measured at present. The proposed research is to investigate photoreflectance as a temperature sensor for the above purpose. The energy gap of the semiconductor material would be measured using modulation spectroscopy and correlated to the surface temperature. The Phase I effort demonstrate the feasibility and accuracy of this technique. The Phase II effort would result in a prototype instrument and demonstrate its use in improving practical etching in an industrial environment.
