Browse Prior Art Database

Ion Milling With a Ceramic Mask

IP.com Disclosure Number: IPCOM000101130D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Related People

Bauer, HJ: AUTHOR [+4]

Abstract

A ceramic mask is used to shield the surface of the polyimide during ion milling. By means of this mask, the openings in the polyimide are cleaned from residue and contamination, while the desirable dielectric properties of the polyimide are maintained.

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Ion Milling With a Ceramic Mask

       A ceramic mask is used to shield the surface of the
polyimide during ion milling.  By means of this mask, the openings in
the polyimide are cleaned from residue and contamination, while the
desirable dielectric properties of the polyimide are maintained.

      A polyimide layer is used in integrated circuit and packaging
technology to insulate a first metallization level from a second
metallization level (the latter not being shown in the figure).
Holes are opened in the polyimide where contact is required between
the two levels.  This is followed by ion milling to remove any
residues and oxide layers from the area of the contact surface.

      This ion milling step degrades the desirable dielectric
properties of the polyimide.  A conductive path forms on the surface
of the polyimide between separated metal lines, which leads to
leakage in the metallization.  Such leakage, which is assumed to be
caused by ion bombardment of the polyimide surface, is reduced by
reactive ion etching and ashing after ion milling.

      It has been found that the use of a mask on the surface of
the polyimide layer effectively prevents the formation of such
leakage.  For this purpose, a mask (of, say, ceramic) with cut-outs
that are only slightly larger than the holes in the polyimide may be
placed on the substrate.  The larger cut-outs are used for alignment.