Axiotaxy of CoSi2 thin films on Si(100) substrates and the effects of Ti alloying

Abstract

The texture of CoSi2 films on Si(001) substrates has been examined using synchrotron based high-resolution pole figure analysis. We find that axiotaxy, a recently recognized type of texture which was observed in NiSi thin films on Si(001), is also occurring in CoSi2 layers. Typical of axiotaxy texturing, the CoSi2 pole figures show symmetrical patterns of lines. Calculations show that these features on the pole figures are created by three off-normal fiberlike texture components. These off-normal fiber orientations are a consequence of the alignment of CoSi2〈110〉 planes with Si〈110〉 planes because of very similar d spacings, which causes a periodic arrangement along Si〈100〉 directions in the plane of the interface. This one-dimensional periodicity may provide a lower interfacial energy; however, the periodic arrangement along the Si〈100〉 directions may also be indicative of growth anisotropy. The influence of Ti alloying has been investigated by using in situ x-ray diffraction measurements, as well as pole figure analysis. These results show that the nucleation of both the CoSi and CoSi2 phases is delayed to higher temperatures for the 5 at. % Ti alloyed films. The texture of the CoSi2 phase is also influenced by the addition of Ti.