Selective epitaxial growth of silicon
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A. Feygenson AT&T Bell Laboratories, 600 Mountain Avenue, Murray Hill, New Jersey 07974-2070
J. J. Bastek, J. C. C. Tsai, and H. C. Praefcke AT&T Bell Laboratories, 2525 North 12th Street, Reading, Pennsylvania 19612-3566 E. W. Bonato AT&T Bell Laboratories, 555 Union Boulevard, Allentown, Pennsylvania 18103 (Received 8 February 1990; accepted 24 June 1991)
We have studied selective epitaxial growth of silicon in the SiCl 2 H 2 /HCl/H 2 system. Our results on growth rate and selectivity are reported here. We found that the growth rate and selectivity are strong functions of the partial pressures of HC1, SiCl 2 H 2 , H 2 , exposed Si area, and wafer position. We propose that growth and selectivity are controlled by surface reactions between SiCl 2 H 2 and HC1 and the SiO2 and Si surfaces. Higher HC1 flow rates decrease the adsorption coefficients and/or incorporation rates of the reactive SiCl2H2(g) species on both SiO2 and Si. When either is zero for SiO2 and both are greater than zero on Si, selective depositions occur. Finally, we present data on the effect various SiO2 surface treatments have on the density and distribution of Si nuclei on this surface.
I. INTRODUCTION
II. EXPERIMENTAL PROCEDURE
Selective Epitaxial Growth (SEG) of silicon is receiving a considerable amount of attention as an isolation technology for advanced integrated circuit processes because it offers a number of unique advantages over the standard LOCOS-like isolation.1"9 These advantages include, but are not limited to, independent formation of n and p wells with or without buried layers, multiple well resistivity, both deep and shallow isolation, low temperature processing, and a relatively "simple" process in that only one mask per well is required. Furthermore, the final structure has a planar surface between isolation oxide and the epitaxial well. Obviously, the process is viable only if selectivity is maintained. This is generally obtained by the addition of HC1 to the H 2 /SiCl 2 H 2 gas system.9 It is generally believed that the added HC1 etches the Si nuclei that form on the SiO2 faster than it etches the epitaxial silicon grown in the silicon wells, and thus selective depositions can be achieved. Claasen and Bloem, however, have suggested that surface nucleation effects are also important.10 In the paper we present our data on the growth rate and selectivity for SEG silicon in the SiCl 2 H 2 /HCl/H 2 system and compare them to previously published data. Finally, we present data on the effects various commonly used SEG oxide surface treatments have on silicon nucleation and growth on SiO 2 .
A. SEG nucleation and growth
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J. Mater. Res., Vol. 6, No. 11, Nov 1991
http://journals.cambridge.org
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The SEG substrates were (100), 8-15 0-cm ptype, 75 mm diameter wafers with a (100) major flat. Approximately 1.0 /xm of SiO 2 was grown on the wafers at 1100 °C in wet O 2 . The SiO2 was then patterned with photoresist and the oxide was etched to the silicon surface. Following the photoresist strip, the wafe
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