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Co(Si1-xGex)2 Epitaxial Metallization on Si

IP.com Disclosure Number: IPCOM000120714D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 40K

Publishing Venue

IBM

Related People

Thompson, RD: AUTHOR [+4]

Abstract

Disclosed is a technique for growing an epitaxial metallization film on Si where the growth of epitaxial Si on top of the metallization is enhanced by utilizing a ternary alloy to reduce the strain from the mismatch in lattice parameters and possibly also the surface energy of the metallization layer. CoSi2 has been the metallization with the fewest defects when such an epitaxial structure (Si/metallization/Si) is grown, but still is not of sufficient quality to use in VLSI devices. The addition of Ge to the metallization reduces the strain due to lattice mismatch (CoSi2 = 1.2%) and alters the surface energy. Both of these result in lower defect levels, but the resulting ternary alloy is not thermodynamically stable.

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Co(Si1-xGex)2 Epitaxial Metallization on Si

      Disclosed is a technique for growing an epitaxial metallization
film on Si where the growth of epitaxial Si on top of the
metallization is enhanced by utilizing a ternary alloy to reduce the
strain from the mismatch in lattice parameters and possibly also the
surface energy of the metallization layer.  CoSi2 has been the
metallization with the fewest defects when such an epitaxial
structure (Si/metallization/Si) is grown, but still is not of
sufficient quality to use in VLSI devices.  The addition of Ge to the
metallization reduces the strain due to lattice mismatch (CoSi2 =
1.2%) and alters the surface energy.  Both of these result in lower
defect levels, but the resulting ternary alloy is not
thermodynamically stable.

      The epitaxial growth of metastable Co(Si1-xGex)2 has been
carried out by simultaneous deposition of the three elements with the
desired ratio (Co may be deficient) at an elevated temperature.  The
Co deficient ratios have been shown to reduce the defect levels when
growing CoSi2 and have been used for all the ternary alloy we have
grown.  The growth temperature for lowest defect levels is dependent
on the Ge content of the alloy and other growth conditions. The
thermodynamically stable two phase mixture of Co(Si1-xGex) and
Si1-yGey will form if the temperature is too low and the quality of
the epitaxy suffers if it is too high.  A range near 600"C gives good
results for many different set...