A multi-sensor study of Cl 2 etching of polycrystalline Si

Abstract

Cl 2 chemistries are the basis for etching of polycrystalline Si and other conductive gate materials in Si CMOS integrated circuit fabrication. It is now well-known that recombination of atomic Cl neutrals on the chamber walls influences the etch rate and thus leads to manufacturing reproducibility problems. In this work, we make use of multiple real-time measurements to improve the understanding of the physical mechanisms for this effect. In particular, real-time spectroscopic ellipsometry is used as both a poly-Si etch rate monitor and as a virtual SiCl 4 flow rate sensor. This aids in the quantitative interpretation of the optical emission spectroscopy data. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)