Ti/CrxOy-Cr/Cu/Cr DEVICE INTERCONNECTION METALLURGY
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Future products will require increased current-carrying capability with increased conductivity. Pure copper metallurgy at the second and subsequent levels would be advantageous. Formation of gross amounts of CuAl2 intermetallic at the first-to-second level interfaces in the vias makes it obvious that the aluminum (Al) at first level should also be replaced with copper (Cu). This, however, raised the specter of semiconductor junction "poisoning" by the Cu. To prevent this junction "poisoning", a composite barrier layer consisting of titanium (Ti) plus chromium (Cr) and chromium oxides may be used at the interface. The Ti has the dual function of providing (1) a low barrier Schottky barrier diode interface, when desired, as well as (2) a mechanical barrier to help prevent the penetration of Cu into the semiconductor junction.