High resolution electron microscopy of amorphous interlayers between metal thin films and silicon

High-resolution electron microscopy of amorphous interlayers (a-interlayer) formed by solid-state diffusion between metal thin films and silicon is reviewed. In this paper, an overview of the development is presented. Pertinent data obtained on the growth kinetics and structure of a-interlayers in polycrystalline metal thin films on single-crystal silicon are reported. For the Ti/Si, Zr/Si, Hf/Si, V/Si, Nb/Si and Ta/Si systems, the growth of a-interlayer was found to follow a linear law in the initial stage. Si atoms were found to be the dominant diffusing species in the solid phase amorphization in the Ti/Si, Zr/Si, and Hf/Si systems. For the Y/Si system, the stability of amorphous interlayer depends critically on the composition of the amorphous films. Auto-correlation function analysis was utilized to determine the structure of the amorphous interlayers. HRTEM in conjunction with the fast Fourier transform were applied to determine the first nucleated crystalline phase. Simultaneous presence of multiphases was observed to occur in a number of refractory metal/Si systems.