Chapter 9 - The Growth of Silicides and Germanides

Abstract

Metallic silicides and germanides are used as contact materials on source/drain and gate in metal oxide semiconductor (MOS) structures such as transistors or memories. They are fabricated by reaction between a metal or a metallic alloy thin film and the Si (Ge) substrate. If one excludes oxidation, this type of thin film reaction has arguably been the most studied, and a lot of works have been devoted to understanding such reactions. In addition to the fundamental interest, this research is driven by the continuous down-scaling of the microelectronics devices and the consequent decrease of contacts' size that bring challenges for the growth of silicides and germanides both for the very thin thickness (below 10 nm) of the film and for the limited place (smaller than 10×10 nm2) where the growth takes place. Phenomena like nucleation, lateral growth, interfacial reaction, stress, texture, and transient phase formation play a large role and have to be understood and possibly controlled for applications. The industrial constraints have also lead to a change in the silicide used for the contact from TiSi2, CoSi2, and NiSi. Actually, alloy elements such as Pt are added to the Ni silicide to improve the properties of the contacts. The presence of alloy elements as well as stress and defects induced by the confinement in devices may have an effect on the silicide formation mechanism and alloying element redistribution.