Subject: Comment raith SNF 2007-07-25 18:07:39: Electrostatic chuck calibrations completed
From: jwc@snf.stanford.edu
Date: Wed, 25 Jul 2007 18:07:39 -0700

RAITH adjustments to the ESChuck during the last service call were not completed correctly
leaving a total delta WD of 165 - 174 um on 150 mm wafers mounted on the ESChuck.
This was not suitable for high resolution EBL and many tests were exposed to some degree
of out of focus.
  Figure of merit for a 100 nm features was determined from 15 runs exposed and inspected
by optical microscope HPV.  For a 100 nm single pixel line or area write to resolve
the sample holder needs to be flat within a total delta WD of < 30 um or less at 10
kV AND 30 um aperture at 5 mm WD.
10 kv 10 um aperture 5 mm working distance limited data indicates total delta WD should
be within 15 - 17 nm. more test necessary to render a suitable confidence in these measurements.
THE UNIVERSAL SAMPLE HOLDER is still well out of specification and it cannot be adjusted.
 Measuerments made of 100 mm wafers mounted on this holder exhibit a range of measurements
for the same conditions from a total delta WD between 125 and 174 um.  data measurements
indicate normal wear and tear consistent with usage on this holder, values are steadily
increasing. (5 years...) 
Working with RAITH USA to obtain a new generation Universal sample holder that is adjustable
and suitable for leveling on our laser interferometer Stage is in quotation, and further
negotiations will determine ultimate cost to SNF.  Rx: the universal sample holder is
worn out and needs to be replaces as soon as a replacement is available.
Thank you for your support!
James Conway