Chemical Stability of HBF₄-Treated (100)Si Surfaces

Abstract

Si(100) surfaces were modified by means of enhanced RCA procedure with “ HBF4-last” and “HF-last”. Nulling ellipsometric (NE) and secondary ion mass spectrometric (SIMS) measurements revealed that HBF4-treated Si surface is more strongly passivated by hydrogen and fluorine than HF-treated one: the oxidation rate of the HBF4-treated Si surfaces in air was found to be lower than that of the HF-treate surface. Scanning tunneling microscope (STM) images of HBF4-cleaned surface after 18 h storage in air were quite stable during observation, scanning could be easily performed over a wide area on every plot we chose.

Chemical treatment effect of Si(111) surfaces in F-based aqueous solutions

“…Hydrophobicity and hydrophilicity have been identified with the existence of certain chemical species on the surface: 27 The origin of hydrophilicity is singular and associated OH groups on the Si surface, while hydrophobic surfaces are mainly characterized by Si-H and probably also O and C in minor quantities. SIMS analysis indicated 8 bonds clearly exist on HBF 4 -treated surfaces. Hence it is likely that the Si-F bond should be the cause for hydrophilicity.…”

“…Such adsorbed chemical species may affect the ellipsometric data and result in modification of the dielectric function. 8,14,25,26 The different ͗⑀ 2 ͑E 2 ͒͘ values may correspond to the different numbers of H ͑F͒ atoms adsorpted on the chemically treated surfaces. Our ͗⑀ 2 ͑E 2 ͒͘ results can suggest an order for the number of the adsorbed H ͑F͒ species,…”

“…Indeed, Levenets et al 8 performed SIMS measurements on HF-and HBF 4 -treated samples and observed stronger H and F peaks in the SIMS bargraph of the HBF 4 -treated sample. The contact-angle measurements reveal obvious difference in the wettability behavior between the HF-͑NH 4 F-͒ and HBF 4 -treated samples ͑Fig.…”

“…More recently, Levenets et al 8 found from nulling ellipsometric and secondary-ion-mass spectroscopy ͑SIMS͒ measurements that a HBF 4 -treated Si surface is more strongly passivated by hydrogen and flourine than a HF-treated one. The oxidation rate of the HBF 4 -treated surface in air was found to be lower than that of the HF-treated one.…”

Chemical Treatment Effects on Si(111) Surfaces in Aqueous NaF Solution

“…4,5) Recently, several authors have reported that treatment with aqueous HBF 4 solution results in the removal of the surface native oxide and may leave behind the silicon surface terminated by atomic hydrogen and fluorine. [6][7][8] The fluorine species were identified by secondary-ion mass spectroscopy 6) and X-ray photoelectron spectroscopy (XPS). 8) It has also been shown 8,9) that aqueous NH 4 BF 4 and H 2 SiF 6 solutions can etch-remove the silicon native oxide and leave behind a shiny flat surface.…”