Gentle FUSI NiSi metal gate process for high- k dielectric screening

Abstract

In this paper, a process flow well suited for screening of novel high- k dielectrics is presented. In vacuo silicon capping of the dielectrics excludes process and handling induced influences especially if hygroscopic materials are investigated. A gentle, low thermal budget process is demonstrated to form metal gate electrodes by turning the silicon capping into a fully silicided nickel silicide. This process enables the investigation of rare earth oxide based high- k dielectrics and specifically their intrinsic material properties using metal oxide semiconductor (MOS) capacitors. We demonstrate the formation of nickel monosilicide electrodes which show smooth interfaces to the lanthanum- and gadolinium-based high- k oxide films. The dielectrics have equivalent oxide thicknesses of EOT = 0.95 nm (lanthanum silicate) and EOT = 0.6 nm (epitaxial gadolinium oxide).