摘要
The growth kinetics of amorphous interlayer (a-interlayer) and formation of crystalline suicide phases in ultrahigh vacuum deposited polycrystalline Er and Tb thin films on (001)Si have been investigated by cross-section transmission electron microscopy. The growth of the amorphous interlayer in both Er/Si and Tb/Si systems was observed to exhibit similar behaviors. The growth was found to follow a linear growth law initially in samples annealed at 190-240°C. The activation energy of the linear growth and maximum thickness of the a-interlayer were measured to be 0.5 eV, 15.5 nm, and 0.35 eV, 16 nm in Er/Si and Tb/Si systems, respectively. Crystalline suicides (ErSi 2-x or TbSi 2-x ) were found to form at the amorphous interlayer/Si interfaces in samples after prolonged and/or high-temperature annealing. Simultaneous growth of the a-interlayer and crystalline phase was observed and the growth rate of a-interlayer was faster than the growth of epitaxial ErSi 2-x and TbSi 2-x phases in samples annealed at 270-300°C in Er/Si and Tb/Si systems, respectively. The competitive growth can be understood from energetic consideration. A high density of recessed amorphous regions were found to form between isolated epitaxial suicide regions which led to uneven silicide/Si interfaces and eventually pinholes in the suicide films at high temperatures. The formation mechanism of rough silicide/Si interface is discussed. © 1997 American Institute of Physics.