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Wet Etching Process for Fully Cured and High Temperature Annealed Polyimides

IP.com Disclosure Number: IPCOM000103812D
Original Publication Date: 1993-Feb-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Feger, C: AUTHOR [+4]

Abstract

Disclosed is an inexpensive and fast wet etching process that effectively etches fully cured polyimide including fully cured polyimide annealed at high temperatures, e.g., 400ºC, using commonly used chemicals.

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Wet Etching Process for Fully Cured and High Temperature Annealed Polyimides

      Disclosed is an inexpensive and fast wet etching process that
effectively etches fully cured polyimide including fully cured
polyimide annealed at high temperatures, e.g., 400ºC, using
commonly used chemicals.

      The process utilizes three steps (base, acid, base)-

o   Imide ring opening in 1 molar potassium on sodium hydroxide
    solutions in a solvent mixture of ethanol/water (75%/25% to
    85%/15%).  Exposure time 6-10 minutes at 50º, followed by
    water rinse;

o   Regeneration of the polyamic acid from the potassium salt of the
    polyamic acid using 1 molar hydrochloric or acetic acid in an
    ethanol/water solvent mix;

o   Etching of polyamic acid in a potassium hydroxide solution.
    Typical ethanol/water solvent mixtures are 75%/25% to 85%/15%.
    However, lower ethanol content at this step may be as good or

    better.  An exposure time of 5 to 10 minutes is followed by a
    water rinse.

Patterns can be etched in a polyimide substrate by first coating the
substrate with a resist type material which can withstand the harsh
alkaline treatment of steps a and c, e.g., KTFR1* and Waycoat2**
photoresists.  For large dimension patterns a screanable resist,
e.g., polystyrene, KTFR and Waycoat can be used.

      A screening process saves considerable time by eliminating all
the steps associated with photolithography.

      O...