Browse Prior Art Database

Methods for Manufacturing Self Aligning Phase Shift Masks

IP.com Disclosure Number: IPCOM000107461D
Original Publication Date: 1992-Feb-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 1 page(s) / 53K

Publishing Venue

IBM

Related People

Bajuk, SP: AUTHOR [+5]

Abstract

A self-aligned phase-shift mask fabrication technique is described in which a 180-degree phase-shifting rim is added around each mask aperture defined by opaque material, such as chrome. The rim is integral to the mask and is defined by the primary lithographic process. This technique yields a structurally rugged mask since the phase-shifting rim material bridges each aperture to support the opaque material. The overall result is a durable mask that enhances the resolution of a given photolithography tool.

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Methods for Manufacturing Self Aligning Phase Shift Masks

      A self-aligned phase-shift mask fabrication technique is
described in which a 180-degree phase-shifting rim is added around
each mask aperture defined by opaque material, such as chrome.  The
rim is integral to the mask and is defined by the primary
lithographic process.  This technique yields a structurally rugged
mask since the phase-shifting rim material bridges each aperture to
support the opaque material.  The overall result is a durable mask
that enhances the resolution of a given photolithography tool.

      The complete mask consists of a transparent planar substrate
material, such as silicon dioxide, coated on one surface with an
opaque material, such as chrome.  Apertures etched through the chrome
and partially into the substrate are lined with a phaseshifting rim
material, such as silicon dioxide.  The figure shows that the center
of the rim material is recessed below the surface of the opaque
material by a distance that produces a 180-degree phase-shift for the
exposing light.

      The composite mask can be used with any isolated aperture shape
and is not dependent on periodic grouped features or special pattern
recognition schemes.  The phase-shifting rim is effective in
eliminating chrome etchback at each aperture and yields a mask that
is easily cleaned and repaired.

      Disclosed anonymously.