Cl{sub 2} plasma etching of Si(100): Nature of the chlorinated surface layer studied by angle-resolved x-ray photoelectron spectroscopy

Journal Article · Thu May 01 04:00:00 EDT 1997 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.365216· OSTI ID:554247

Layadi, N; Donnelly, V M; Lee, J T ^[1]

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1. Bell Laboratories, Lucent Technologies, 600 Mountain Avenue, Murray Hill, New Jersey 07974 (United States)

It was found that the amount of chlorine incorporated into the near-surface region of Si increases with ion energy, and does not change with long exposure to the plasma. Chlorine is present as SiCl{sub x} (x=1{endash}3) with average relative coverages (integrated over depth) of [SiCl]:[SiCl{sub 2}]:[SiCl{sub 3}]{congruent}1:0.33:0.13 at {minus}240V dc bias (mean ion energy {approx}280eV) and 1:0.34:0.087 at 0 V dc bias (mean ion energy {approx}40eV), at x-ray photoelectron spectroscopy (XPS) binding energies of 100.2, 101.2 and 102.3 eV, respectively. Moreover, there is a substantial amount of disordered Si within the chlorinated layer at high ion energy, reflected in a broadening of the 99.4 eV Si peak and the appearance of a shoulder at 98.8 eV, ascribed to Si with a dangling bond. In addition, bulk Si plasmon losses associated with the Cl(2p) and Cl(2s) core levels indicate that roughly one-third of the Cl in the near-surface region is surrounded by bulklike Si at the high ion energy. Modeling of the dependence of the relative concentration of Cl on the take-off angle was used to estimate the Cl content and thickness of the surface layer. From an inversion of the observed take-off angle dependence of the relative Cl and Si XPS signals, depth profiles were derived for the near-surface region. Cl content falls off in a graded fashion, over a depth of about 25 and 13 {Angstrom} for a mean ion energies of 280 and 40 eV, respectively. The Cl areal density (coverage integrated throughout the layer) increases with increasing mean ion energy from 1.8{times}10{sup 15}Cl/cm{sup 2} at 40 eV to 3.5{times}10{sup 15}Cl/cm{sup 2} at 280 eV. From a similar inversion of the take-off angle dependence of the SiCl{sub x} signals, SiCl{sub 2} and SiCl{sub 3} are found to be largely confined at the top {approximately}5{Angstrom}, while below the surface, disordered Si and SiCl are present. {copyright} {ital 1997 American Institute of Physics.}

• OSTI ID: 554247
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 10 Vol. 81; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
BINDING ENERGY
CHEMICAL REACTIONS
CHLORINE
ETCHING
PHOTOELECTRON SPECTROSCOPY
PLASMA
SILICON
SURFACES