Adapted wavelength methods for in situ ellipsometry

For real time ellipsometry monitoring, the choice of measurement of wavelength can be advantageously adapted to the controlled parameter. Adapted wavelength ellipsometry is illustrated here by two examples. Firstly, a simple method based on the choice of an appropriate wavelength for thickness control is presented. This method requires no information on the underlaying structure and is well suited to control deposition of multilayer stacks such as Bragg reflectors. Examples of fabrication control are presented. Secondly, we report results of temperature measurements. Semiconductor spectroscopic ellipsometry had shown that there is a wavelength range within which the optical response is relatively insensitive to temperature and that there are other wavelengths in which it is highly sensitive. Thus, according to the wavelength, ellipsometry can be used to measure temperature, or, to measure other parameters taking the temperature effect into account. (C) 1998 Elsevier Science S.A.