Enhanced thermal stability of NiSi films on Si(111) substrates by a thin Pt interlayer

A thin interlayer of Pt can greatly enhance the thermal stability of NiSi f ilms formed by rapid thermal annealing (RTA) on Si(1 1 1) substrates, as wa s revealed by X-ray diffraction (XRD) data and sheet resistance measurement . High-resolution transmission electron microscopy (HRTEM) reveals a well-d efined interface between the Ni(Pt)Si film and the Sill II) substrate for t he Ni/Pt/Si sample annealed at 640 degreesC. The orientation relationship i n this sample determined by selected area electron diffraction (SAED) was N iSi(1 0 0)//Si(1 1 1) and NiSi[0 (1) over bar0]//Si[0 1 (1) over bar]. With the increase of temperature, the texture of NiSi films transform from NiSi (1 0 0)//Si(1 1 1) to NiSi(0 0 1)//Si(1 1 1). The reduction in the interfac ial energy due to the formation of the (1 0 0) textured NiSi film is propos ed as a possible reason for the improved thermal stability of NiSi and the transition in NiSi texture during high-temperature annealing. Detailed stud y on the XRD data combined with Auger electron spectra (AES) indicates PtSi and NiSi form a solid solution following Vegard's law, which adjusts the l attice constant ratio c/b to root3 and may account for the texture of NiSi( 1 0 0)//Si(1 1 1). (C) 2000 Published by Elsevier Science B.V.