Failure of zirconium silicide contacts during the silicidation process studied by AES and RBS

Abstract

The electronic properties and resistance to processing chemicals of zirconium disilicide suggest that it is a possible alternative material to titanium silicide for contact and interconnect structures in VLSI. The purpose of this work was to address the practical problems involved in the use of this material for contact applications. Simple p-n junction diodes were produced by boron implantation into n-type single crystal silicon wafers of (100) orientation. Zirconium silicide contacts were produced on these diodes by deposition of thin zirconium metal layers, and subsequent annealing under various temperatures and ambient atmospheres. Those contacts annealed in a gas atmosphere were heated in a standard tube furnace and studied, before and after annealing, with a combination of Auger electron spectroscopy (AES) and Rutherford Backscattering (RBS). Those which were annealed in vacuum were heated in a uhv chamber using an electron bombardment heater and studied, in situ, at various stages of the silicidation process, also by AES and RBS. A description of the combined electron spectrometer, RBS spectrometer and its associated pumping system will also be given.