Comment raith SNF 2007-07-25 18:07:39: NO 2. Electrostatic chuck calibrations completed -- UNIVERSAL SAMPLE HOLDER continues to be out of specification for flatness.

James Conway jwc at snf.stanford.edu
Wed Jul 25 18:24:03 PDT 2007


RAITH adjustments to the Electro Static Chuck (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 to resolve 100 nm features was determined from 15 
runs exposed and inspected by optical microscope HPV and SEM:
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 
keV AND 30 um aperture at 5 mm WD.


For 10 keV, 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 mechanically adjusted.  Measurements 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.
While this was to be corrected during the last service visit by placing 
shims in P1 and P2 piezo post to correct this problem further testing 
indicated that this was not completed correctly.

   My data and measurements have revealed indications of normal wear and 
tear consistent with usage on the universal sample holder, values are 
steadily increasing. (5 years...)

Working with RAITH USA to obtain a next generation Universal Sample 
Holder that is adjustable and suitable for leveling on our laser 
interferometer Stage. Currently in quotation, and further negotiations 
will determine ultimate cost to SNF. This is a consumable item and not 
covered within the service contract.

Conclusions: The universal sample holder is worn out and needs to be 
replaces as soon as a replacement is available to ensure high resolution 
EBL exposures of quality for a majority of our Users.

Users are requested to always carefully inspect their Ebeam writes after 
development and to promptly report their results to this list.

Users working with whole wafers interested in using the ESChuck for 
their writes should see me to schedule training and to do a run together.

Thank you for your support!

James Conway
Ebeam Lab SNF




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