Subject: Problem raith SNF 2007-02-14 16:21:21: Standard sample holder not landing onto piezo post properly
From: jwc@snf.stanford.edu
Date: Wed, 14 Feb 2007 16:21:22 -0800

Attention All RAITH Users:
PROBLEM ON RAITH: STANDARD SAMPLE HOLDER NOT LANDING ON KINETIC MOUNTS -- DAMAGED PIEZO
POST...
I have been troubleshooting several user reports of irregularly shaped or poorly defined
written structures on the exposures made since January 11, 2007.  This issue has become
more apparent through the month, and as we perform Hi resolution measurements of our
structures in SEM reviewwritten in early January.
I have observed several incidents of out of focus or poorly focused structures written
at the extreme edges of wafers ( EG targets and SPLines @ 0, -45 UV :: 0 +45 UV) Within
the normal +- 10 mm range I often write within, I also observed significant changes
in working distance as I moved through this small range of positions.
Monday and today we made measurements of the surface of both a 100 mm wafer clipped
to the standard sample holder and upon the Std. sample holder itself and have collected
data that the holder is not landing precisely flat into the kinetic mounts.  The range
of non-flatness is ~ 0.500 mm!
Visual and SEM inspection of the ceramic balls and points or 'jewel' tips in the Piezo
post yield information that indicated that Piezo one post ceramic ball may have also
become damaged and the point may be missing. All piezo post exhibit wear on their surfaces
Users are requested to be vigilant of their actual working distances, and to report
their WD data for specific positions across their samples and promptly report to this
list if you see significant changes in WD as you move across your wafers greater than
250 um.
RAITH has been contacted last Friday and we will strive to correct this issue ASAP.
System is now in YELLOW Light Mode.
Thank you for your support!
James Conway