Comparison of the thermal stability of NiSi films in Ni/Pt/(111)Si and Ni/Pt/(100)Si systems.

The thermal stability of NiSi films in Ni/Pt/(111)Si and Ni/Pt/(100)Si bilayered systems was investigated. In the Ni/Pt/(111)Si system, the NiSi films formed at 640 °C have an epitaxial relationship of (100)NiSi||(111)Si and [01¯0]NiSi||[011¯]Si with the substrates. On the other hand, those formed on (100)Si substrates were polycrystalline although the experimental parameters are the same as those in Ni/Pt/(111)Si samples. In both cases, NiSi and PtSi formed a solid solution Ni[sub 1-x]Pt[sub x]Si following Vegard’s law. While the thermal stability of NiSi films is improved in both cases compared with the Ni/Si system, the thermal stability of the textured NiSi films formed on (111)Si substrates is higher than their polycrystalline counterparts formed on (100)Si substrates. This is attributed to the reduced interfacial energy and consequently increased activation energy for the nucleation of NiSi[sub 2] due to the formation of textured NiSi films on (111)Si substrates. At 900 °C, the Ni(Pt)Si film formed in Ni/Pt/(100)Si system decomposed into separate phases of NiSi and PtSi with noticeable lattice deformation. Differences between the texture evolution of NiSi films in Ni/Pt/Si and Ni(Pt) alloy/Si systems were also reported and explained from both kinetic and thermodynamic aspects. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]