AUGER-ELECTRON SPECTROSCOPY AND RUTHERFORD BACKSCATTERING CHARACTERIZATION OF TINX/TISIY CONTACT BARRIER METALLIZATION

We have studied both the formation and integrity of TiN(x)/TiSi(y) bilayer films formed by reacting sputter deposited Ti films on Si substrates in nitrogen containing ambients. Auger electron spectroscopy and Rutherford backscattering spectrometry have been used to characterize the formation and properties of these bilayer films as a function of the ambient composition, the substrate doping, and the method of heating [furance or rapid thermal annealing (RTA)]. We have also characterized the B and As substrate dopant redistribution which occurs during the bilayer formation. Barrier integrity was measured by depositing 2 k angstrom of Al-Si(1%)-Cu(1%) on top of the TiN(x)/TiSi(y) bilayers and thermally stressing the films at 450-degrees-C for times ranging from 0.5 to 6.0 h. The metallurigical breakdown of the Al/barrier/Si was characterized by Auger depth profiling and the integrity of the barriers was correlated with the various parameters of the barrier formation. It is concluded that the properties of the nitride/silicide bilayer as a whole (rather than the nitride layer alone) must be considered in order to optimize the barrier performance. In particular, barriers with incompletely reacted Ti layers show inferior performance relative to those with more completely reacted Ti layers, and this characteristic is of greater importance than the nitride thickness in determining the barrier integrity. Barrier effectiveness is diminished by either p+ or n+ substrate doping through the dopant induced inhibition of the silicidation reaction. Native oxides prevalent on n+ substrates and their effect on the silicidation reaction have also been studied.