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Acidification of Salts at the Polymer Surface Formed in the Re-work Process or in the Chromium Etch Process

IP.com Disclosure Number: IPCOM000109482D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 1 page(s) / 63K

Publishing Venue

IBM

Related People

Lee, K: AUTHOR

Abstract

Disclosed is a method for converting the salt form of polyimide surface, which is formed in the re-work process or chromium-etch process, to polyamic acid that can be cured to polyimide.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 68% of the total text.

Acidification of Salts at the Polymer Surface Formed in the Re-work Process or in the Chromium Etch Process

      Disclosed is a method for converting the salt form of polyimide
surface, which is formed in the re-work process or chromium-etch
process, to polyamic acid that can be cured to polyimide.

      Polyimides are used as dielectric layers in a variety of
microelectronic applications, as they have good processability, low
dielectric constant, high thermal stability, low moisture absorption,
and good mechanical properties.  If the applied layer of polymer is
not acceptable in the process, the layer is usually removed with a
concentrated solution of base (NaOH, KOH or ammonium hydroxides).
The surface of the bottom polyimide layer is modified to potassium
(or corresponding cationic) polyamate salt.  This salt layer in a
real part probably causes corrosion due to the metal ions.

      A solution of KMnO4 and KOH is employed to etch off the
chromium layer from the part which contains polyimides.  During this
Cr etch process, Mn complex of polyimide is formed.  This salt
probably causes corrosion or dielectric loss.

      To prevent the corrosion and dielectric loss by the salt or the
Mn complex of polyimide at the polymer surface, the polymer salt or
the Mn complex is treated with mild acetic acid to transform the salt
to polyamic acid.  The formed polyamic acid is converted to polyimide
in the curing process of the top layer polyimide.  Since the...