Browse Prior Art Database

Improved Resist Structure for Lift-Off Metallization

IP.com Disclosure Number: IPCOM000103286D
Original Publication Date: 1990-Sep-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 48K

Publishing Venue

IBM

Related People

Broersma, DM: AUTHOR [+3]

Abstract

An improved electron-beam (E-beam) resist structure and process for producing metal conductive lines on integrated circuits by a "lift-off" method is described. A novel feature of the disclosed tri-level structure involves the use of a titanium-tungsten (Ti-W) intermediate layer which serves both as a discharge layer and as an RIE barrier.

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Improved Resist Structure for Lift-Off Metallization

      An improved electron-beam (E-beam) resist structure and process
for producing metal conductive lines on integrated circuits by a
"lift-off" method is described.  A novel feature of the disclosed
tri-level structure involves the use of a titanium-tungsten (Ti-W)
intermediate layer which serves both as a discharge layer and as an
RIE barrier.

      The structure shown in the Figure consists of an organic resin
layer 1 applied over the substrate, a thin metal layer 2 over the
surface of the organic resin, and an electron beam positive resist
layer 3 applied over the metal layer surface.  Preferred embodiments
of these components are:  layer 1, a polysulfone, polyimide, or
polyvinylphenol based resist material; layer 2, a titanium-tungsten
alloy; and layer 3, a photosensitive organic material from the group
consisting of diazoquinone- novolaks, polymethyl methacrylates,
polymethyl isopropenyl and phenol ketones, nitroaldehydes, and
polyolefin sulfones.

      The disclosed resist structure is employed to produce a
positive pattern which is then coated with aluminum-copper (Al-Cu)
and a wiring pattern finally obtained by solvent "lift-off" of the
organic resin.  The optimum thickness of the Ti-W layer depends upon
the specific process application, but is in the order of 500
angstroms.  For applications where greater resist sensitivity or
minimal proximity effect is desired, the Ti-W layer thickness can...