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High Dielectric Amorphous Oxide for Capacitors in VLSI Technology

IP.com Disclosure Number: IPCOM000120189D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 40K

Publishing Venue

IBM

Related People

dHeurle, FM: AUTHOR [+4]

Abstract

VLSI circuits require the incorporation of capacitors which cannot be readily made from thermal silicon oxide because the dielectric constant is too low, requiring too large surfaces in order to achieve the desired capacitance. In order to circumvent this problem, one uses various complicated and costly techniques, such as the use of trenches. An alternative is to use other dielectric materials with a sufficiently high constant.

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High Dielectric Amorphous Oxide for Capacitors in VLSI Technology

      VLSI circuits require the incorporation of capacitors which
cannot be readily made from thermal silicon oxide because the
dielectric constant is too low, requiring too large surfaces in order
to achieve the desired capacitance.  In order to circumvent this
problem, one uses various complicated and costly techniques, such as
the use of trenches.  An alternative is to use other dielectric
materials with a sufficiently high constant.

      Such a material is Ta2O5 with a dielectric constant of about
20.  The problem with this compound is that it crystallizes at a
temperature too low for usual device processing, and then loses its
desirable dielectric properties.  This inconvenience should be
eliminated through the use of a mixed Ta2O5-Nb2O5 with a composition
within the solubility gap of the two oxides, namely from 50 mol% to
75 mol% Ta2O5 .  It is well known that such a mixture of materials
exhibits crystallization temperatures well in excess of those
displayed by the individual components. Such a mixed oxide would
probably have a lower dielectric constant than pure Ta2O5, but even
if Nb2O5 had a dielectric constant near zero, the mixture would have
a dielectric constant three to four times that of SiO2, which would
be satisfactory for a broad range of applications.  The oxide could
be obtained by codeposition either via evaporation or sputtering of
the metals in the desired proportions fol...