Effects of substrate cleaning and film thickness on the epitaxial growth of ultrahigh vacuum deposited Cu thin films on (001)Si

The effects of substrate cleaning and film thickness on the epitaxial growth of ultrahigh vacuum (UHV) deposited Cu thin films on (001)Si have been investigated by transmission electron microscopy (TEM), X-ray diffractometry and Auger electron spectroscopy. In as-deposited samples, Cu films were found to grow preferentially along the [111] direction on atomically clean (2 x 1)(001)Si reconstructed surface and grow along the [001] direction on hydrogen terminated (001)Si. The Cu lattice is rotated by 45 degrees relative to Si along the [001]Cu/[001]Si axis. The alignment of the Cu overlayer was found to improve with the distance from the Cu/Si interface using electron diffraction and high resolution TEM analysis, Similar results were obtained for non-UHV processed samples.