Growth of pinhole-free ytterbium silicide film by solid-state reaction on Si(001) with a thin amorphous Si interlayer

Abstract

A thin amorphous Si (α-Si) interlayer is produced between the sputtering deposited ytterbium layer and Si(001) substrate, and the growth of the ytterbium silicide (YbSi2−x) film is investigated in this paper. Formation of YbSi2−x was verified by x-ray diffraction (XRD). The silicide film morphology was examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). SEM results reveal that without the α-Si interlayer, pinholes form during YbSi2−x formation on Si(001). Furthermore, the XRD results demonstrate that there is a strong epitaxial relationship between the formed YbSi2−x and Si(001) substrate, and it is believed to be the reason for the formation of pinholes. To suppress the formation of pinholes, a thin α-Si interlayer with different thicknesses is introduced on the Si(001) substrate prior to Yb film deposition. The α-Si interlayer is produced by either sputter deposition employing a Si target or by Si ion implantation induced amorphization. In the presence of this thin α-Si interlayer, epitaxial growth of YbSi2−x is greatly suppressed even when the α-Si interlayer is so thin that full silicidation of the deposited Yb film still requires consumption of Si atoms from the Si(001) substrate. Fabrication of a pinhole-free YbSi2−x film is also demonstrated by SEM and AFM. The growth mechanism of the pinhole-free YbSi2−x film in the presence of a thin α-Si interlayer is discussed.