Doped Titanium Films for Salicide and Polycide
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09
Addition of small amounts of Pb (less than 1%) and Cu (less than 3%) in sputtered Ti films for applications in self-aligned TiSi2 structures or in polycide structures (TiSi2 on poly-Si) was found to be beneficial. The doping of Ti with these "impurities" was unintentional. This happened when the Ti target wore out and developed small holes through which the bonding solder and the copper backing material began migrating to the sputtering surface and reached the substrates. Figs. 1 and 2 show the presence of these impurities as examined by Rutherford Backscattering Spectroscopy (RBS). Fig. 1 RBS data shows the presence of Pb and Cu impurities in sputtered Ti film, and Fig. 2 shows after reaction with Si substrate at 800ŒC, 20 minutes in N2 .