Browse Prior Art Database

Method to Selectively Planarize Silicon Dioxide Surfaces Using Polyimide as an Etch Stop

IP.com Disclosure Number: IPCOM000121930D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Biolsi, PE: AUTHOR [+3]

Abstract

Described is a method by which a silicon dioxide surface which has topography can be planarized yielding an oxide surface of uniform thickness using polyimide as an etch stop.

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This is the abbreviated version, containing approximately 72% of the total text.

Method to Selectively Planarize Silicon Dioxide Surfaces Using Polyimide
as an Etch Stop

      Described is a method by which a silicon dioxide surface
which has topography can be planarized yielding an oxide surface of
uniform thickness using polyimide as an etch stop.

      The method is particularly useful in thin film semiconductor
circuit fabrication since it provides an effective means of improving
the oxide thickness uniformity when the surface is eventually
planarized.  Typically, the use of chemical-mechanical (chem-mech)
polishing for SiO2 planarization presents processing problems as
removal rates increase.  The resulting high deviations in the oxide
film thickness occur on wafers with topography being removed at
differing removal rates across the surface.  Large features polish
slower than smaller features. Where the raised features are removed
first, the previous lower lying areas will begin to have material
removed, causing a depression in that area of the film.

      The concept described herein provides a thin layer of polyimide
that protects the low lying regions from being removed by polishing
until the raised topography on the other areas of the wafer is
removed.  This is accomplished by applying a thin layer, 2000-5000
angstroms thick, of polyimide.  The polyimide coats the wafer and the
SiO2 topography uniformly.  The selectivity of the chem-mech
polishing slurry used for the SiO2 removal is 6:1 SiO2/polyimide.  As
the polyimide on...