Effects of an interposed Cu layer on the enhanced thermal stability of C49 TiSi2

The effects of an interposed Cu layer and a surface Cu layer on the C49–C54 TiSi2 transformation temperature were studied. For the Ti/Cu/(100)Si samples the interposed Cu layer significantly enhanced the thermal stability of C49 TiSi2. The temperature for complete C49–C54 TiSi2 transformation was raised from 710 to 735 to 750 °C with the thickness of the interposed Cu layer increasing from 0 to 1.5 to 3.5 nm, correspondingly. Cu was insoluble in C54 TiSi2. For the Cu/Ti/(100)Si samples, the surface Cu layer did not at all enhance the thermal stability of the C49 phase. In the present study, the enhanced thermal stability of C49 TiCuxSi2–x can be attributed to its reduced electron/atom ratio and larger grain size relative to those of C49 TiSi2.