In-situ film thickness measurements by using pyrometric interferometry

A novel optical in situ method for film thickness measurements, pyrometric interferometry (PI), is introduced, which is capable of high-resolution (0.5 nm) data acquisition during the process (in situ measurement) and real-time data evaluation. It can be used for process control as well as for online quality inspection without time delay or additional handling mechanisms and is suitable for monitoring single films as well as multilayer structures. PI is insensitive to mechanical vibrations and hostile environments such as high temperature and/or chemical reactive gases. Its technical realization is achieved by using standard components, thus providing a very competitive cost-effectiveness ratio. In situ PI film thickness measurements on a SiO₂ layer growing on a silicon substrate by thermal oxidation are presented, as well as on a SiO₂/Si coating by CVD (chemical vapor deposition). The potential technical impact of PI on automation, reliability, and long-term performance of manufacturing operations is also discussed