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Conducting Metal Oxides as Buffer Layers for Ferroelectric Film Growth

IP.com Disclosure Number: IPCOM000106688D
Original Publication Date: 1993-Dec-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Robertazzi, R: AUTHOR [+2]

Abstract

Disclosed is a process for depositing ferroelectric thin films on silicon. It entails the use of conducting metal oxide films as buffer layers between the silicon and the ferroelectric film. Ferroelectic films like SrTiO sub 3 need to be deposited at high temperature in ambient O sub 2 in order to form films with bulk dielectric properties. In order to form capacitor structures on Si, a conducting buffer layer is needed which is oxygen resistant under these conditions. Proposed is the use of conducting metal oxides (e.g., RuO sub 2 and ReO sub 3) as the buffer layer material for growing these high dielectric constant films.

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Conducting Metal Oxides as Buffer Layers for Ferroelectric Film Growth

      Disclosed is a process for depositing ferroelectric thin films
on silicon.  It entails the use of conducting metal oxide films as
buffer layers between the silicon and the ferroelectric film.
Ferroelectic films like SrTiO sub 3 need to be deposited at high
temperature in ambient O sub 2 in order to form films with bulk
dielectric properties.  In order to form capacitor structures on Si,
a conducting buffer layer is needed which is oxygen resistant under
these conditions.  Proposed is the use of conducting metal oxides
(e.g., RuO sub 2 and ReO sub 3) as the buffer layer material for
growing these high dielectric constant films.

      SrTiO sub 3 has a room temperature dielectric constant &epsilon
.sim 300 .  The dielectric properties arise from the crystal
structure of the material.  When SrTiO sub 3 is deposited at room
temperature, the film is amorphous.  It is only when the film is
deposited at elevated temperature (.sim 700 .deg C) and in an
 O sub 2  ambient that the desired crystal structure forms.  This
poses a problem when trying to grow films on Si though as these
conditions cause a thin thermal  SiO sub 2  layer to form which
inhibits crystalline SrTiO sub 3 growth and forms a thin electrically
insulating layer.

      The feasibility of RuO sub 2 as a diffusion barrier between Si
and Al, and other metallurgies has been shown in [1].  Recently, [2]
has demonstrated...