In situ spectroscopic ellipsometry: present status and future needs for thin film characterisation and process control

Principle and limitations of real time spectroscopic ellipsometry are presented. The technical characteristics of the SOPRA ES4G IIA system are summarised and illustrated by practical examples. With 1024 pixels in a spectral range of 260–1060 nm, a reproducibility better than 10−3 and the possibility to record 40 spectra per second in groups of eight pixels, this instrument can fulfil a great part of the present in situ characterisation requirements. The next generation, which will be more dedicated to process control, will also be presented and discussed in terms of precision, speed and accuracy. The major importance of spectral range and resolution will be demonstrated in practical cases.