AVS 57th International Symposium & Exhibition
    Spectroscopic Ellipsometry Focus Topic Thursday Sessions
       Session EL+AS+EM+MS+TF-ThA

Paper EL+AS+EM+MS+TF-ThA9
In-situ Temperature Measurements by Spectroscopic Ellipsometry: Application to a-Si based Thin Films

Thursday, October 21, 2010, 4:40 pm, Room Cochiti

Session: Spectroscopic Ellipsometry
Presenter: D. Daineka, LPICM, CNRS, Ecole Polytechnique, France
Authors: D. Daineka, LPICM, CNRS, Ecole Polytechnique, France
V. Suendo, Institut Teknologi Bandung, Indonesia
P. Roca i Cabarrocas, LPICM, CNRS, Ecole Polytechnique, France
Correspondent: Click to Email
Accurate measurement of the substrate temperature is of crucial importance in many semiconductor technologies such as plasma enhanced chemical vapor deposition (PECVD). Traditional tools, both thermocouples and pyrometers, are not always reliable for in situ measurements in vacuum when the substrate can be out of thermal equilibrium. On the other hand, non-contacting optical methods allow to determine the surface temperature with great accuracy, provided the temperature dependence of optical constants for the studied material is known. Since recently, spectroscopic ellipsometers are widely available and often installed on the research deposition systems, which provides an opportunity to use them for temperature monitoring. We have studied the optical functions of amorphous silicon based thin films with spectroscopic ellipsometry in the temperature range from 290 to 520 K. The experimental data were modeled using Tauc-Lorentz dispersion law for amorphous materials. We have found that the temperature coefficients of Tauc-Lorentz parameters, such as the optical gap, are rather close for a few different materials. That similarity suggests that these values can be used to determine the surface temperature for a broad range of amorphous silicon based materials with a good accuracy. Practical examples of using spectroscopic ellipsometry for temperature measurements in the low pressure PECVD environment are given.