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ABSTRACT: Metal suicides have played an indispensable role in the rapid developments of microelectronics since PtSi was first used to improve the rectifying characteristics of diodes in early 1960s. This work first provides a brief historical overview of the many different suicides, and, correspondingly, the different processing methodologies used in the past. With regard to the present use of suicides in CMOS technologies, a convergence becomes clear with the self-aligned technology using only a limited number of silicides, namely, TiSi^sub 2^, CoSi^sub 2^, and NiSi. A section on fundamental aspects is included to cover thermodynamics and kinetics, which are essential for understanding the silicide formation processes. The advantages and disadvantages and disadvantages of TiSi^sub 2^. CoSi^sub 2^, and NiSi are analyzed with the development trend of CMOS technologies as a measure. Specifically, the reactive diffusion and phase formation of these silicides in the three terminals of a metal-oxide-semiconductor device, that is, gate, source, and drain, are scrutinized. The review ends with an extended discussion about future trends of metal silicides in micro/ nanoelectronics, with reference to the potential material aspects and device structures outlined in the International Technology Roadmap for Semiconductors.
1. INTRODUCTION
The rapid advancement in microelectronics during the last 40 years has been realized through miniaturization and integration of the electronic devices. Advances in miniaturization and very-- large-scale integration (VLSI) allow for computer intelligence to be built into products that are smaller, integrate more complex functions, consume less power, and cost less. According to the 2002 update of the International Technology Roadmap for Semiconductors (ITRS),1 this rapid pace of development will continue well into the next decade. It is known that metal-oxide-semiconductor field-effect-transistor (MOSFET) is the basic building block for the absolute majority of today's electronic systems. Therefore, the focus is placed on the use of metal suicides for MOS devices in the present article. A cross section of two modern MOSFETs placed side-by-side is shown schematically in Figure 1, with a metal silicide layer present in the three electrode terminals, gate, source, and drain for both transistors. The silicide layer is usually formed simultaneously in all six electrode areas. The two transistors are of opposite polarity, one n-channel MOSFET (nMOSFET) built directly on the p-type substrate and one p-channel MOSFET (pMOSFET) built...