Cl-2 surface chemistry on Cu/Si(100): an ISS, XPS, and TPD study

The chemistry of Cl-2 on a Cu/Si(1 0 0) (at relatively high near surface co ncentrations of Cu) surface has been investigated using X-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD), and ion scatt ering spectroscopy (ISS). XPS and ISS suggested that the deposition of Cu a t 120 K on Si(1 0 0) resulted in Cu/Si intermixed layers. Heating this surf ace led to the rapid decrease of Cu in the outermost layer based on ISS, an d by 600 K there was no Cu-derived scattering peak even though XPS showed t here was a significant amount of Cu in the near surface region. Based on th ese experimental observations it is postulated that islanding of Cu/Si part icles occurred, which is supported by prior studies. Adsorption of Cl-2 on the 120 K-Cu deposited Si(1 0 0) surface led to some Cu agglomeration, base d on XPS. TPD results showed that SiCl4 desorbed from this surface at 530 K and SiCl2 desorbed near 1000 K. The latter peak occurs at the same desorpt ion temperature as SiCl2 for Cl-2/Si(1 0 0) and is thus attributed to the t hermal chemistry of Cl-2 on bare Si(1 0 0). It is likely, however, that the 530 K desorption feature was a direct result of the weakened surface bondi ng of Si in Cu/Si islands, compared to Si on bare Si(1 0 0). (C) 2001 Elsev ier Science B.V. All rights reserved.