Abstract
The use of sulfur-containing organic monolayer films improves adhesion between gold and silicon dioxide. The structures of these monolayers were analyzed using contact angle, ellipsometry, and XPS. The zone of adhesive failure was at or near the gold-monolayer interface.
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References And Notes
G. Upite and S. Varenca, Tezisy Dokl. Vses. Simp. Akt. Pverkhn. Tel 2, 55 (1977); Chem. Abstr. 92, 14451j (1980).
K.H. Muecke, Metalloberfläche 31, 506 (1977); Chem. Abstr. 88, 31077b (1978).
Fujitsu Ltd., Japanese Patent 48/98732 (1983); Chem. Abstr. 101, 63762z (1984).
G. J. Zydzik, L.G. Van Uitert, S. Singh, and T.R. Kyle, Appl. Phys. Lett. 31, 697 (1977).
I. V. Mitchell, J. S. Williams, P. Smith, and R. G. Elliman, Appl. Phys. Lett. 44, 193 (1984).
B.T. Werner, T. Vreeland, Jr., M. H. Mendenhall, Y. Qui, and T. A. Tombrello, Thin Solid Films 104, 163 (1983).
J.E. Griffith, Y. Qui, and T.A. Tombrello, Nucl. Instrum. Methods Phys. Res. 198, 607 (1982); Chem. Abstr. 97, 119011x (1982).
M.K. Chaudhury and E. P. Plueddemann, J. Adhesion Sci. Tech. 1, 243 (1987).
R. G. Nuzzo and D. L. Allara, J. Am. Chem. Soc. 105, 4481 (1983).
C.D. Bain, E.B. Troughton, Y-T. Tao, J. Evall, and G. M. Whitesides, J. Am. Chem. Soc. 111, 321 (1989).
M.D. Porter, T.B. Bright, D.L. Allara, and C.E.D. Chidsey, J. Am. Chem. Soc. 109, 3559 (1987).
E.B. Troughton, C.D. Bain, G. M. Whitesides, R.G. Nuzzo, D.L. Allara, and M. D. Porter, Langmuir 4, 365 (1988).
R. G. Nuzzo, B.R. Zegarski, and L. H. Dubois, J. Am. Chem. Soc. 109, 733 (1987).
Stable bis(alkylthiolate) gold(I) salts (Au(SR)2−) have been prepared by reaction of Au(I) dihalides with alkylthiolates. G. A. Bowmaker and B.C. Dobson, J. Chem. Soc., Dalton Trans., 267 (1981).
D.L. Allara, A. F. Heburd, F.J. Padden, R.G. Nuzzo, and D.R. Falcon, J. Vac. Sci. Technol. A, 376 (1983).
D. L. Allara and R. G. Nuzzo, U.S. Patent 4690715 (1987).
K.R. Stewart, G. M. Whitesides, H. P. Godfried, and I.F. Silvera, Rev. Sci. Instrum. 57, 1381 (1986).
F. Pintchovski, J.B. Price, P. J. Tobin, J. Peavey, and K. Kobold, J. Electrochem. Soc. 126, 1428 (1979).
Solutions of 1 were used within 48 h of preparation. While a rigorously dry atmosphere was not required, too high a water content in the atmosphere resulted in polymerization and precipitation of the starting silane.
S.R. Wasserman, Y-T. Tao, and G.M. Whitesides, Langmuir (in press).
The thioacetate was subjected to acidic rather than basic hydrolysis since monolayers from alkyltrichlorosilanes are not stable in base.
This range is not significant. Ellipsometric measurements for organic monolayers on silicon have a precision of ± 2 Å.
Monolayers prepared from methyl-terminated alkyltrichlorosilanes are apparently oriented nearly perpendicular (tilt angle ≈ 14 ± 18°) to the substrate surface in a trans -extended chain. R. Maoz and J. Sagiv, J. Colloid Interface Sci. 100, 465 (1984). N. Tillman, A. Ulman, J.S. Schildkraut, and T. L. Penner, J. Am. Chem. Soc. 110, 6136 (1988).
S.R. Wasserman, G.M. Whitesides, I.M. Tidswell, B. Ocko, P.S. Pershan, and J. D. Axe, J. Am. Chem. Soc. (in press).
The bond lengths of typical C–S and C–C bonds are 1.85 and 1.54 Å, respectively. Assuming a bond angle of 120°, we would predict a decrease of 2.93 Å upon hydrolysis of the thioacetate group in a completely formed monolayer. For the partial monolayers studied here, this predicted change must be corrected for the fractional coverage of the surface, in this case approximately 60%. For these monolayers the expected change in length would therefore be approximately 2 Å. CRC Handbook of Chemistry and Physics, edited by R. C. Weast (CRC Press, Boca Raton, FL, 1984), 65th ed., pp. F-166-F-167.
C.D. Bain, H.A. Biebuyck, and G.M. Whitesides, Langmuir (in press).
We do not know whether this binding energy indicates the presence of a thiol or of a disulfide. The difference in the binding energies of the S 2p electrons in a thiol (163.3 eV) and a disulfide (163.0 eV) is small. Values for the S 2s electrons are expected to differ by similar amounts. The difference in these binding energies is similar to the errors in our reference peaks. See Refs. 13 and 26.
Adhesive failure for the thiol-terminated monolayers occurred, on average, in ~15% of the total area covered by the tape. On individual samples failure was found over 2–50% of the surface. For the thioacetate-terminated monolayers, failure occurred only on 25% of the samples and removed gold from less than 1 % of the area covered by the tape. We believe that this difference in failure rates probably reflects contamination of the thiol interface during the hydrolysis of the thioacetate group.
Since the monolayers prepared from HTS were longer than those created from 1, the Au/C ratio exaggerates the difference in the amount of gold left on these surfaces. Comparisons to the Si 2p signal, which underestimates this difference, indicate that at least six times as much gold was left on the thiol-terminated interface as on the methyl-terminated one.
The binding energy of the gold is referenced to an average of the C 1s, O 1s, and Si 2p signals.
The binding energy of the sulfur in the thiol-terminated monolayer (228.4 eV) was between that of the sulfur in the thioacetate group (228.7 eV) and that of the sulfur in the thiol bound to the gold (228.0 eV). Uncertainties in the reference peaks were, however, almost as large as this shift.
The difference in the 2p binding energy for a sulfur in a thiol group and that in a thiolate form (RS−) is ~ 2.8 eV. Values for the S 2s electrons are expected to differ by similar amounts. B.J. Lindberg, K. Hamrin, G. Johansson, Y. Gelius, A. Fahlman, C. Nordling, K. Siegbahn, Physica Scripta 1, 286 (1970).
G.K. Wertheim, S.B. DiCenzo, and S.E. Youngquist, Phys. Rev. Lett. 51, 2310 (1983).
E. Lukevics, Z. V. Belyakova, M. G. Pomerantseva, and M. G. Voronkov, in Journal of Organometallic Chemistry Library 5: Organometallic Chemistry Reviews, edited by D. Seyferth, A. G. Davies, E. O. Fischer, J. F. Normant, and O. A. Reutov (Elsevier, Amsterdam, 1977), pp. 1–179 and the references therein.
E L. McCracken, E. Passaglia, R. R. Stromberg, and H. L. Steinberg, J. Res. Natl. Bur. Stand., Sect. A. 67, 363 (1963).
These sensitivities are those provided by Surface Science Laboratories in their ESCA 8.0B software. These sensitivities reflect both the inherent photoionization cross section of each element and the dependence of the mean free path of an electron on its energy. J. H. Scofield, J. Electron Spectrosc. 8, 129 (1976).
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Wasserman, S.R., Biebuyck, H. & Whitesides, G.M. Monolayers of 11-trichlorosilylundecyl thioacetate: A system that promotes adhesion between silicon dioxide and evaporated gold. Journal of Materials Research 4, 886–892 (1989). https://doi.org/10.1557/JMR.1989.0886
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DOI: https://doi.org/10.1557/JMR.1989.0886