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Doped Titanium Films for Salicide and Polycide

IP.com Disclosure Number: IPCOM000060825D
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Ahn, KY: AUTHOR [+2]

Abstract

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 .

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Doped Titanium Films for Salicide and Polycide

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 800OEC, 20 minutes in N2 . The thickness of the Ti film is approximately 550 A, and the amounts of Pb and Cu range from 0.5 to 3% depending upon the location of the 9 wafers in a pallet in the sputtering system. After annealing, as done for the regular salicide process, these films become TiSi2 with improved electrical resistivity. Fig. 2 shows the formation of TiSi2 after annealing at 800OEC for 20 minutes in N2 . Despite the presence of impurities, no increase in electrical resistivity was observed. In fact, the reaction temperature needed to form the TiSi2 is found to be lower, as shown in Fig. 3 which illustrates the annealing behavior of sputtered films with (solid line) and without (dotted line) Pb an...