Dilute hydrogen plasma cleaning of boron from silicon after etching of HfO{sub 2} films in BCl{sub 3} plasmas: Substrate temperature dependence
- Department of Chemical and Biomolecular Enginneering, University of Houston, 4800 Calhoun Road, Houston, Texas 77204 (United States)
The authors have investigated the effects of elevated substrate temperature (T{sub s}) on cleaning of boron residues from silicon substrates in 1%H{sub 2}-Ar plasmas, following etching of HfO{sub 2} in BCl{sub 3} plasmas. Vacuum-transfer x-ray photoelectron spectroscopy (XPS) provided a measure of total B removal rates, as well as information on individual BCl{sub x}O{sub y} moities. B cleaning rates increased with T{sub s} in an Arrhenius manner, with an apparent activation energy of 1.7 kcal/mol. Conversely, the Si etching rate decreased with increasing substrate temperature with an apparent activation energy of -0.8 kcal/mol. Therefore, when considering selectivity with respect to Si etching, it is advantageous to remove B at higher T{sub s}. For example, at T{sub s}=235 deg. C, {approx}90% of B is cleaned from Si in 10 s, while <1.5 nm of Si is removed. An apparent diffusion of H into the near-surface region of Si at higher temperatures, detected indirectly by a shift and broadening of the Si(2p) XPS peak, may limit the maximum optimum substrate temperature, however. It was also found that Si does not etch in 1%H{sub 2}/Ar plasmas if an oxide layer is present.
- OSTI ID:
- 21194985
- Journal Information:
- Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films, Vol. 27, Issue 1; Other Information: DOI: 10.1116/1.3054131; (c) 2009 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1553-1813
- Country of Publication:
- United States
- Language:
- English
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