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Intrinsic Stress Control in Thin Metal and Metal Alloy Films

IP.com Disclosure Number: IPCOM000115647D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Jones Jr, RE: AUTHOR [+2]

Abstract

A method is disclosed for controlling the intrinsic stress in RF sputtered thin metal and metal alloy films by adding small concentrations of metal atoms with different diameters from those of the base metal film.

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Intrinsic Stress Control in Thin Metal and Metal Alloy Films

      A method is disclosed for controlling the intrinsic stress in
RF sputtered thin metal and metal alloy films by adding small
concentrations of metal atoms with different diameters from those of
the base metal film.

      Intrinsic stress in RF sputter deposited films can be modified
by adding concentrations of metal atoms with different diameters.  A
relationship is obeyed of the form:
    S - SO = KCD,
  where S is the residual stress of the metal alloy film of
interest, SO is the residual stress of the corresponding pure metal
film, K is a positive constant, C is the fractional concentration of
the added metal, and D is the relative difference between the
diameter
of the host atom, dhost, and the diameter of the added atom,
dadditive:
    D = (dhost - dadditive)/dhost.

      The validity of this relationship for RF sputtered films is
shown in the Figure.  In this case small concentrations of
aluminum(diameter(1) = 2.83A), silicon(2.63A), tantalum(2.94A), and
titanium(2.93A) were added to a base iron film(2.52A).

      The diameters for these additives were larger than those of the
atoms of the base film, so the stress associated with the additives
is compressive.  Since the intrinsic stress of most RF sputtered pure
metal films is tensile, this implies that it is possible to offset
the intrinsic stress in RF sputtered films by small selected amounts
of additional metals with sui...