<i>In situ</i> physical vapor deposition of ionized Ti and TiN thin films using hollow cathode magnetron plasma source

Abstract

The in situ deposition of titanium (Ti) and titanium nitride (TiN) films for aggressive contacts [diameter &amp;lt;0.25 μm diameter, with aspect ratio (AR)∼5] using the hollow cathode magnetron (HCM)™ plasma source has been demonstrated. The TiN films were deposited in an in situ non-nitrided (metallic) mode and the deposition rates are high (&amp;gt;700 Å/min) for both Ti and TiN. Rutherford backscattering data demonstrated that the process is truly non-nitrided, and that the Ti deposited after a TiN deposition does not contain any significant amounts of atomic nitrogen in it. In addition, TiN with low resistivity (∼30 μΩ cm for a 1000 Å film) is obtained. Due to the high fractional ionization of the sputtered titanium, a bottom coverage of &amp;gt;30% (5:1 aspect ratio, 0.25 μm) is obtained for both Ti and TiN without application of rf bias to the wafer pedestal. Contact resistances of the liner barrier film were compared to the control films that were deposited using collimation. The HCM Ti and TiN films show lower contact resistance for both n+ and p+ contacts. The spread in the contact resistances is also minimal, indicating within-wafer bottom coverage uniformity that is better than the control films. The as-deposited TiN acted as a good enough barrier to allow subsequent chemical vapor deposition W fill on these 5:1 AR structures. This is the first demonstrated case of in situ deposition of ionized Ti and TiN in the same chamber without the use of a collimator or a shutter present between the target and the wafer.