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Low Leakage, Temperature Invariant, High Dielectric Constant Films, using Multilayered Sol-Gel Fabrication

IP.com Disclosure Number: IPCOM000113522D
Original Publication Date: 1994-Sep-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 75K

Publishing Venue

IBM

Related People

Beach, DB: AUTHOR [+4]

Abstract

Disclosed is a method for fabrication of ferroelectric, paraelectric, or relaxor coatings to controllable minimize grain size and to prevent continuous grain growth through the thickness of the coating, and to reduce the temperature dependence of the dielectric constant of such coatings.

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Low Leakage, Temperature Invariant, High Dielectric Constant Films,
using Multilayered Sol-Gel Fabrication

      Disclosed is a method for fabrication of ferroelectric,
paraelectric, or relaxor coatings to controllable minimize grain size
and to prevent continuous grain growth through the thickness of the
coating, and to reduce the temperature dependence of the dielectric
constant of such coatings.

      Expansion of DRAMs to higher densities, for 1 Gbit memory or
higher, requires high dielectric constant materials in order to be
able to maintain a workable level of charge in the reduced surface
area of such high density elements.  Ferroelectric, paraelectric, or
relaxor materials are characterized by high dielectric constants
which might be sufficient to satisfy the requirements of 1 Gbit
DRAMs.  Many of these materials also have remanent polarization
values large enough that they are suitable for non volatile memory
applications.  On the other hand, many of such high dielectric
constant layers are characterized by a strong dependence of the
dielectric constant on temperature, and thin films of such materials
show relatively low electrical resistivities, precluding their
utilization in memory devices.

      Temperature sensitivity can be overcome by choosing a
combination of materials having compensating temperature dependence.
Current leakage may be reduced by grain size control along the Z axis
of the capacitor, by the interruption of grain structure to a
dimension below the percolation limit.  The sol gel method can be
used to deposit multilayered structures composed of thin films, each
about 100-200 &angstrom.  thick, of materials having high dielectric
constants.  The films can be alternating layers of different
materials, (A/B/A/B), or of same material with slight variations in
composition (A/'A' sup */A/'A' sup *).  The variation in composition
of the alternating layers prevents their homoepitaxy (epitaxial grain
growth from layer to layer), thus preventing the formation of
continuous columnar grains th...