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X-Ray Single Layer Resist Process for Metal Lift-off

IP.com Disclosure Number: IPCOM000121722D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 169K

Publishing Venue

IBM

Related People

Perreault, SE: AUTHOR [+2]

Abstract

Disclosed is a process for definition of metal wiring layers on semiconductor substrates using X-ray lithography. This process exploits the low absorption in organic resists of X-ray energy in the 8-10- Angstrom wavelength range. Using appropriate exposure energy, vertical profile resist features can be accurately defined in thick single-layer resists. In the proposed process, the resist film is intentionally overexposed, creating an undercut profile suitable for metal lift-off patterning. With certain photoresists, it is observed that overexposure has little effect on the image with respect to the resist opening size at the surface. This permits accurate mask replication over a wide range of doses.

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X-Ray Single Layer Resist Process for Metal Lift-off

      Disclosed is a process for definition of metal wiring
layers on semiconductor substrates using X-ray lithography.  This
process exploits the low absorption in organic resists of X-ray
energy in the 8-10- Angstrom wavelength range.  Using appropriate
exposure energy, vertical profile resist features can be accurately
defined in thick single-layer resists.  In the proposed process, the
resist film is intentionally overexposed, creating an undercut
profile suitable for metal lift-off patterning.  With certain
photoresists, it is observed that overexposure has little effect on
the image with respect to the resist opening size at the surface.
This permits accurate mask replication over a wide range of doses.
Thus, unlike conventional optical lithographic imaging, resist
overexposure in X-ray patterning need not compromise linewidth
control latitude.

      This overexposure technique provides the basis for simplified
metal patterning using a single-layer resist process.   The resist
layer is patterned via proximity printing on a synchrotron-based
X-ray stepper using about twice the normal imaging dose.  Following
resist development, undercut profiles are obtained which, after
optional UV stabilization, serve as stencils for evaporation of the
desired metal layer.  Unwanted metal is then lifted off using a
solvent capable of swelling and/or dissolving the resist layer.
This single-layer approach greatly si...