Scanning Micro-Spot Auger Spectroscopy Study of Interdiffusion and Eutectic Formation in W-Pt-W-Au Thin Films

Reactions in rf sputtered W-Pt-W-A,u films on oxidized and unoxidized Si substrates have been analyzed using a micro-spot scanning Auger spectroscopy and microscopy technique. The analysis shows that the W-Pt-W-Au films on Si substrates have undergone three annealing stages resulting in gold-silicon eutectic formation and migration. Stage I (450°C, 12 hours) was characterized by the formation of Si rich globular regions on the Au film. During Stag,,, II (450°C, 24 hours) the entire unreacted gold film was consumed. Finally, during Stage III (550°C, 24 hourS) gold and the liquid phase eutectic migrated toward the metal-Si interface. For W-Pt-W-Au on oxidized Si substrates, the diffusion barrier of W-Pt-W was observed to be effective up to 550°C tot 24 hours.