FORMATION OF METAL/SiGe/Si CONTACTS FOR ULSI APPLICATIONS

Yukio Yasuda, Osamu Nakatsuka and Shigeaki Zaima*

Department of Crystalline Materials Science, School of Engineering, Nagoya University

*Center for Cooperative Research in Advanced Science and Technology, Nagoya University

Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan

The increase in parasitic series resistances such as contact resistance of metal/Si interface has become one of the most serious problems with shrinking the dimension in ultra-large scale integrated (ULSI) devices. The use of Si1-xGex as an intermediate layer between metal and Si is expected to reduce the contact resistance due to decreasing the Schottky barrier height (SBH), compared with metal/Si contacts. This application has many advantages, such as (1) good compatibility with Si processes, (2) controllability of the bandgap and (3) possibility in higher doping concentrations of impurities than those in Si system. We will discuss on the formation of metal germanosilicides and the lowering in the SBH and contact resistivity, in Ti and Zr/Si1-xGex/Si systems.