Structure and morphology of polycrystalline silicon-single crystal silicon interfaces

Using high resolution transmission electron microscopy, morphological aspects of the polycrystalline silicon (polysilicon)-single crystal silicon interface have been correlated to the surface treatment used prior to polysilicon deposition, and to high-temperature annealing. Specimens which were chemically oxidized prior to the deposition exhibited a continuous layer of amorphous oxide ∼15 Å thick; high-temperature annealing results in the formation of small discontinuities in this oxide, and thus small regions of epitaxial realignment within the polysilicon layer. Specimens which were etched in HF prior to deposition were characterized by nearly oxide-free interfaces, and, following high-temperature annealing, exhibited regions of epitaxial realignment an order of magnitude larger than those found in the chemically oxidized samples.