Noncontact surface temperature measurement during reactive-ion etching using fluorescent polymer films

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Abstract
We have used a fluorescence technique to make a noncontact surface-temperature measurement on a thin film of glass resin as it is etched away in a reactive-ion-etching chamber. The glass resin is heavily doped with a fluorescent material whose fluorescence lifetime is temperature dependent. The fluorescence is excited and collected through a remote optical fiber, and the lifetime is measured using a phase-shift technique. The calibration reproducibility of this measurement is about ±1 °C. The fluorescent glass-resin film could be used as an underlayer for monitoring the etching of overlying oxides, photoresists, or patterned metallizations, or a photoresist itself could be doped with the fluorescer. This demonstration opens up the possibility of surface temperature measurement in a wide variety of harsh environments.