Nonintrusive wafer temperature measurement using in situ ellipsometry

Abstract
It is shown that in situ HeNe laser ellipsometric measurements performed during and after rf plasma exposure of a Si wafer with or without oxide can be used to obtain the wafer temperature during plasma exposure. The method utilizes either the temperature coefficient δnT of the refractive index of Si or the linear thermal expansion coefficient δl/lδT of SiO2. The values of these parameters have been redetermined in this work.