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Reliable Capacitor Fabrication Process for GaAs - MMICs

IP.com Disclosure Number: IPCOM000120162D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 43K

Publishing Venue

IBM

Related People

Balasubramanyam, K: AUTHOR [+3]

Abstract

Disclosed is a method for making thin films of sputtered Tantalum Oxide that adhere to the gold based metallization systems used in GaAs integrated circuits. The method is based on the use of an interface metallurgy that better matches the oxidation properties of the dielectric layer.

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Reliable Capacitor Fabrication Process for GaAs - MMICs

      Disclosed is a method for making thin films of sputtered
Tantalum Oxide that adhere to the gold based metallization systems
used in GaAs integrated circuits.  The method is based on the use of
an interface metallurgy that better matches the oxidation properties
of the dielectric layer.

      Tantalum Oxide films are sputter deposited by reacting a
Tantalum target with a gas of 10% oxygen and 90% argon. RF magnetron
sputtering is used.  It is found that films deposited in such a
manner, even over broad ranges of gas pressure, RF power level, and
deposition rates, do not adhere well to the underlying metallization
system of gold that is used in GaAs integrated circuits.  This
vulnerability would make such a film impossible to utilize in an
integrated circuit process.

      The method disclosed is to use an interface metallization
between the tantalum oxide and gold underlying metal.  This interface
metal layer is either platinum or tantalum.  The apparent reason for
the tantalum oxide not adhering directly to the gold is the inability
of the gold to form any oxide.  The gold is too inert.  A platinum or
tantalum interface layer will form enough oxide to bind to the oxide
structure that is being deposited on its surface. This difference in
properties of metal to which the oxide is attempting to adhere is
extremely important in integrated circuit processes, because sputter
deposition tends to put...