Oxidation resistant dilute copper (boron) alloy films prepared by DC-magnetron cosputtering

To enhance me corrosion resistance and reliability of the proposed copper interconnections in silicon integrated circuits, alloying with small amounts thermodynamically favorable elements has been pursued In the present investigation dilute copper (boron) alloy thin films (in boron concentration range of 0-4 at % in copper) were deposited by DC magnetron co-sputtering using a high purity copper and Cu-4 at % B targets. Films were then annealed in Ar-3% H-2, pure Ar, vacuum and air ambients in the temperature range of 200-500 degrees C. Sheet resistance, Rutherford backscattering, x-ray diffraction measurements were made to characterize the films. The residual resistivity of me as-deposited alloy films was found to be 5.3 mu Omega-cm/at %. To obtain sufficiently low working resistivity, an alloy content below 0.5 at % is suggested for application as a potential metallization material. The addition of boron. which is me common dopant in Si, to the copper films offers considerable oxidation protection. The resulting oxidation rates am considerably lower than that for pure copper films, All this will be presented and discussed.