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Mask for Laser Ablation

IP.com Disclosure Number: IPCOM000108163D
Original Publication Date: 1992-Apr-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 50K

Publishing Venue

IBM

Related People

Kaplan, LH: AUTHOR [+2]

Abstract

Disclosed is a mask for laser ablation and a process for its fabrication. The mask has the advantages of low cost and repairability and is aimed primarily at the area of low-volume, early user hardware. It consists of a thin film of highly reflective aluminum (A1), deposited on a quartz substrate, with a thick overlying film of copper (Cu) for energy dissipation. Such masks have been successfully fabricated and used to ablate patterns in typical substrates.

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Mask for Laser Ablation

      Disclosed is a mask for laser ablation and a process for its
fabrication.  The mask has the advantages of low cost and
repairability and is aimed primarily at the area of low-volume, early
user hardware.  It consists of a thin film of highly reflective
aluminum (A1), deposited on a quartz substrate, with a thick
overlying film of copper (Cu) for energy dissipation.  Such masks
have been successfully fabricated and used to ablate patterns in
typical substrates.

      Laser ablation processes cannot use conventional chrome/quartz
masks because the chromium absorbs a substantial fraction of the
incident energy, instantaneously converts it to heat, and rapid
pulsing of the laser increases the metal temperature and destroys it.

      The mask disclosed here is comparatively simple and low in
cost.  It is built on a quartz substrate and the opaque areas are
formed from a 2-layer film.  The metal layer closest to the quartz is
vacuum-deposited A1 or about 0.1 micrometer (um) thickness.  The
quartz/A1 interface has a reflectivity of greater than 90% for most
laser wavelengths of interest.  The second layer, above the A1, is a
3-5 um layer of Cu.  Its purpose is to conduct any absorbed energy
rapidly away from the quartz/A1 interface to prevent its thermal
degradation.

      Patterning of the layers is done by a combination of wet
etching and ion milling, using lithographic masks.

      A cross-section of the laser mask i...