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Adsorption and Desorption Kinetics for Chlorosilanes on Si(111) 7×7

Published online by Cambridge University Press:  25 February 2011

P. Gupta
Affiliation:
Department of Chemistry, Stanford University Stanford, Calif. 94305
P.A. Coon
Affiliation:
Department of Chemistry, Stanford University Stanford, Calif. 94305
B.G. Koehler
Affiliation:
Department of Chemistry, Stanford University Stanford, Calif. 94305
M.L. Wise
Affiliation:
Department of Chemistry, Stanford University Stanford, Calif. 94305
S.M. George
Affiliation:
Department of Chemistry, Stanford University Stanford, Calif. 94305
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Abstract

The adsorption and desorption kinetics for SiCl4 and SiCl2H2 on Si(111) 7×7 were studied using laser-induced thermal desorption (LITD) and temperature programmed desorption (TPD) techniques. Both LITD and TPD experiments monitored SiCl2 as the main desorption product at 950 K at all coverages of SiCl4 and SiCl2H2 on Si(111) 7×7.HC1 desorption at 850 K and H2 desorption at 810 K were also observed following SiCl2H2 adsorption. Isothermal LITD measurements of SiCl4 and SiCl2H2) adsorption on Si(111) 7×7 revealed that the initial reactive sticking coefficient decreased with increasing surface temperature for both molecules. The temperature-dependent sticking coefficients were consistent with precursor-mediated adsorption kinetics. Isothermal LITD studies of SiC12 desorption revealed second-order SiCl2 desorption kinetics. The desorption kinetics were characterizedby a desorption activation energy of Ed = 67 kcal/mol and a preexponential of vd = 3.2 cm2/s. TPD studies observed that the HCI desorption yield decreased relative to H2 and SiCl2 desorption as a function of surface coverage following SiCl2H2 exposure. These results indicate that when more hydrogen desorbs as H2 at higher coverages, The remaining chlorine is forced to desorb as SiCl 2.

Type
Research Article
Copyright
Copyright © Materials Research Society 1991

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References

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