Browse Prior Art Database

Technique to Fabricate Co-Planar Conductors in a Dielectric Layer

IP.com Disclosure Number: IPCOM000101244D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 91K

Publishing Venue

IBM

Related People

Carr, J: AUTHOR [+4]

Abstract

Disclosed is a subtractive technique for fabricating co-planar metal/dielectric structures for thin film packaging applications.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 62% of the total text.

Technique to Fabricate Co-Planar Conductors in a Dielectric Layer

       Disclosed is a subtractive technique for fabricating
co-planar metal/dielectric structures for thin film packaging
applications.

      The need for co-planar structures is apparent for multi-level
thin film wiring.  Traditional techniques like lift-off require a
complex sequence of process steps to create the structure.  Other
newer approaches that use chem-mech polishing suffer from uniformity,
and the problem becomes more acute as the substrate size increases.
This article describes a simple subtractive etching technique that
uses an end- point detection scheme that has a large latitude.  The
process can be applied to any conductor/insulator material set.  The
preferred embodiment described here uses Cu conductors in a polyimide
insulator.

      The process sequence can be described simply as follows:  On
substrate 1 a polyimide film 2 is spun on. This layer is patterned
with features using any established technique such as reactive ion
etching, ion beam etching, microwave etching or the use of
photolithography for a photo-sensitive polyimide.  Over the patterned
polyimide, a metal stack composed of an adhesion layer 3 (e.g. 20 nm
of Cr), a conduction layer 4 (e.g. Cu) of thickness equal to that of
the dielectric layer and a protective top layer 5 (e.g., 50 nm of Cr)
is deposited.  This is shown in Figure 1.  A polishing step is then
used to remove the top Cr layer everywhere e...