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X-Ray Lithography Mask Cleaning Technique

IP.com Disclosure Number: IPCOM000102022D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Vladimirsky, O: AUTHOR [+2]

Abstract

Disclosed is the X-ray lithography mask cleaning procedure designed to prevent the X-ray tools and wafers from gold particle contamination.

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This is the abbreviated version, containing approximately 71% of the total text.

X-Ray Lithography Mask Cleaning Technique

       Disclosed is the X-ray lithography mask cleaning
procedure designed to prevent the X-ray tools and wafers from gold
particle contamination.

      In X-ray lithography masks a 0.5 to 1 mm thick gold film is
commonly used as the absorber.  The gold absorber of the X-ray mask
is formed by electroplating.  Poor adhesion of the plating base and
swelling of the polyimide layer during wet processes (development,
electroplating), especially at the edge of the mask, and uneven
electroplating under the contact ring generates the "edge gold," a
potential source of gold particles.  During the exposure the mask and
the wafer are positioned in a proximity of 20-50 mm, and gold
particles can be easily transferred to the wafer.  Metal
contamination, including gold, is highly undesirable, often
unacceptable, for silicon device fabrication.  The wafer development
and rinsing removes most of these particles.  However, their presence
on the exposed wafers poses a threat of occasional contamination.
Removal of the "edge gold" from the mask will prevent the X-ray tools
and wafers from gold and chromium particle contamination.

      The X-ray mask cleaning procedure includes the following steps
(refer to the figure):
 o  A 1-2 mm thick resist (TNS) is patterned to protect the X-ray
mask gold pattern and aligning marks, using an optical mask and
visible or near UV light exposure and standard development procedure.
      o...