A contact structure is provided incorporating an amorphous titanium nitride barrier
layer formed via low-pressure chemical vapor deposition (LPCVD) utilizing tetrakis-dialkylamido-titanium,
Ti(NMe2)4, as the precursor. The contact structure is fabricated
by etching a contact opening through a dielectric layer down to a diffusion region
to which electrical contact is to be made. Titanium metal is deposited over the
surface of the wafer so that the exposed surface of the diffusion region is completely
covered by a layer of the metal. At least a portion of the titanium metal layer
is eventually converted to titanium silicide, thus providing an excellent conductive
interface at the surface of the diffusion region. A titanium nitride barrier layer
is then deposited using the LPCVD process, coating the walls and floor of the contact
opening. Chemical vapor deposition of polycrystalline silicon or of a metal follows.
