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Methods to Passivate Exposed Copper Surface Before Polyimide Process

IP.com Disclosure Number: IPCOM000108019D
Original Publication Date: 1992-Jan-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Nunes, SL: AUTHOR [+3]

Abstract

It is known that processing polymer films directly on copper can result in degraded packaging performance and cause reliability concerns. Among the observations are higher dielectric constant polymer film, reduced breakdown strength and adhesion degradation at polymer/Cu interface. It is, therefore, necessary to passivate the Cu surface to ensure that both the performance and reliability of the PI-Cu packaging structure can meet the original design requirements without degradations.

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Methods to Passivate Exposed Copper Surface Before Polyimide Process

       It is known that processing polymer films directly on
copper can result in degraded packaging performance and cause
reliability concerns.  Among the observations are higher dielectric
constant polymer film, reduced breakdown strength and adhesion
degradation at polymer/Cu interface.  It is, therefore, necessary to
passivate the Cu surface to ensure that both the performance and
reliability of the PI-Cu packaging structure can meet the original
design requirements without degradations.

      Several methods that can passivate the Cu surface to prevent
PI-Cu interactions are disclosed below.
      (1) Additive patterning
      (a) A single resist layer can be used as lift-off stencil to
pattern the passivation metals on Cu.  This is achieved by the
exposure and development of a resist pattern, same as the underlying
Cu pattern, then coating a thin passivation metal, such as Cr,
followed by lifting- off the resist and Cr in the unwanted area.
      (b) Use a two-layer lift-off structure, such as soluble
PI/resist, to do the patterning.  The resist layer will be silylated,
after exposure and development, and reactive ion etched to create the
same pattern as the Cu underlayer, followed by coating the
passivation metal and lift-off.
      (c) Use electroless plating of passivation metals on exposed Cu
surface.  This approach simplifies the processing steps.
      (2...