Nonintrusive wafer temperature measurement using in situ ellipsometry

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 δn/δT 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.