Self-aligned silicides for Ohmic contacts in complementary metal–oxide–semiconductor technology: TiSi2, CoSi2, and NiSi

Abstract

Metal silicides continue to play an indispensable role during the remarkable development of microelectronics. Along with several other technological innovations, the implementation of the self-aligned silicide technology paved the way for a rapid and successful miniaturization of device dimensions for metal–oxide–semiconductor field-effect transistors (MOSFETs) in pace with the Moore’s law. The use of silicides has also evolved from creating reliable contacts for diodes, to generating high-conductivity current paths for local wiring, and lately to forming low-resistivity electrical contacts for MOSFETs. With respect to the choice of silicides for complementary metal–oxide–semiconductor (CMOS) technology, a convergence has become clear with the self-alignment technology using only a limited number of silicides, namely TiSi2, CoSi2, and NiSi. The present work discusses the advantages and limitations of TiSi2, CoSi2, and NiSi using the development trend of CMOS technology as a measure. Specifically, the reactive diffusion and phase formation of these silicides in the three terminals of a MOSFET, i.e., gate, source, and drain, are analyzed. This work ends with a brief discussion about future trends of metal silicides in micro/nanoelectronics with reference to potential material aspects and device structures outlined in the International Technology Roadmap for Semiconductors.