PROCESSING OF TIN/TI METALLIZATION ON SILICON BY ARSENIC ION-IMPLANTATION

The influence of As+ ion implantation and vacuum annealing on TiN/Ti contact metallizations on silicon was investigated. We have sputter deposited sequentially a 100 nm thick titanium layer and a 50 nm thick TiN layer on p-type Si(111) wafers. The TiN/Ti/Si structures were implanted with As+ at 350 keV, to doses from 1 x 10(14) ions cm-2 to 1 x 10(16) ions cm-2. The projected range of arsenic ions is near the Si-Ti interface. The samples were annealed in vacuum at temperatures from 600-degrees-C to 750-degrees-C, for 2-20 min. Methods of characterization of samples included Rutherford backscattering, transmission electron microscopy and scanning electron microscopy structural analysis and electrical measurements. The TiN layers were found to be an efficient protection from contamination of the TiN/Ti/Si structures, remaining stable throughout the processing. Ion implantation did not induce redistribution of components. Annealing induces the Ti-Si reaction, depending on the annealing time and temperature and on the implanted dose. In samples implanted up to 1 x 10(15) ions cm-2, the low resistivity TiSi2 phase is formed at 750-degrees-C. For higher implanted doses silicidation is retarded. In this case TiSi is formed initially, transforming to the TiSi2 phase for longer annealing times.