INFLUENCE OF ARSENIC ION-IMPLANTATION ON THE FORMATION OF TI-SILICIDES

The effects of arsenic ion implantation on the formation of Ti-silicid es from TiN/Ti bilayer contacts on silicon were investigated. The TiN/ Ti layers were sputter deposited in a single run, 90 nm of Ti and 80 n m of TiN (by reactive sputtering) on (111) Si wafers. The TiN/Ti/c-Si structures were then implanted with As+ ions at 400-500 keV, to the do ses from 1 x 10(15) to 1 x 10(16) ions/cm(2), with the projected ion r ange near the Ti/Si interface. After implantation the samples were the rmally treated in a vacuum, from 2 to 20 min at 650 degrees C and 2-10 min at 900 degrees C. Characterization of samples included RBS, XRD, SEM and electrical measurements. We have observed initial ion beam mix ing at the Ti/Si interface, depending on the As+ ion range. Annealing at 650 degrees C induces the Ti-Si reaction, formation of silicides, w hich strongly depends on the implanted arsenic dose. At 900 degrees C and for low implanted doses the Ti-Si reaction is completed, consuming the whole Ti layer to form the C54 TiSi2 phase, while at high doses t he Ti-Si reaction is retarded, causing segregation of arsenic near the TiN/Ti interface. The top TiN layer remains stable during implantatio n and thermal processing.