Problem raith SNF 2007-02-14 16:21:21: Standard sample holder not landing onto piezo post properly

jwc at jwc at
Wed Feb 14 16:21:22 PST 2007

Attention All RAITH Users:
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

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