In situ real-time studies of nickel silicide phase formation

Abstract
The formation of NiSi films on Si was studied using Rutherford backscattering spectrometry, atomic force microscopy, and ellipsometry. NiSi is an attractive candidate for use as a gate contact material due to its low metal-like resistivity and large processing window (350–750 °C). Three phases, Ni2Si, NiSi, and NiSi2, were identified in this temperature range, and their optical databases in the 2–4 eV photon range were established, and used to model real-time ellipsometry data. It is shown that real-time ellipsometry can be used to monitor and follow the formation of the various Ni–Si phases. We have also observed the onset of agglomeration of the silicide for longer time anneals at temperatures of 500–700 °C, which is much lower than 1000 °C where agglomeration has been reported to occur.