Ti concentration effect on adhesive energy at Cu/TiW interface

Changes in adhesive energy at Cu/TiW interfaces caused by varying the Ti co ncentration were evaluated by means of contact angle measurement. The adhes ive energy was evaluated by applying the Young-Dupre equation to the contac t angle. Copper particles were fabricated by annealing thin Cu film deposit ed on the TiW film. The adhesive energies at the Cu/TiW interface were eval uated as 1.5, 2.1, and 2.6 N/m for a Ti concentration of 0, 10, and 20 wt. %, respectively. The adhesive energies were found to increase almost linear ly as the Ti concentration was increased. These results were applied to pre vent TiW/Cu/TiW interconnects fabricated by using infrared-assisted reactiv e ion etching from peeling at the Cu/TiW interface. In annealing Cu films o n TIW substrates at 600 degrees C in a vacuum, it was found that the Cu pee led from the TiW when the Ti concentration was 10 wt. %, but it stuck to th at at 20 wt. %. The effect of Ti on the adhesion strength was also studied from the results of molecular calculation by using the method. (C) 1998 Ame rican Institute of Physics. [S0021-8979(98)02019-2].