Raith problem --> NO PROBLEM !!

Joseph Klingfus jk at raithusa.com
Wed Jul 14 09:11:25 PDT 2004


Hi there Gigi,

My apologies, of course I shouldn't assume that the pattern generator (PG)
couldn't be broken.  It might be.  Please do the following as a test:

1) Turn the PG off, wait a short time and power back on.
2) Restart both PC's.
2) Check Polaroid 545 setting again on the LEO.
3) Load the Chessy calibration target (as square as possible on the stage)
and go to your normal working distance (stage Z) and set a 100 µm WF.  
4) Because the Chessy is sitting squarely on the stage, the SEM scan
rotation should be 0 and AlignWF rotation values should be nearly 0.
5) Collect a SlowScan image of the Chessy with the PG and see if everything
looks OK.
6) Have the AlignWF window visible on the desktop and try an align WF
procedure.  (Remember, be very aware of your Scansize and Placement values.
There are 1 µm squares composing larger 10 µm squares. Don't confuse which
box intersections are the correct targets.)
7) Write down the calculated zoom correction factors that the system tries
to apply.
8) Hopefully accept the corrections without errors and collect another
SlowScan image.
9) If you selected the right box intersections the Chessy should be
perfectly aligned and sized in the image.

Please let me know how this turns out.

To answer your question of WD...
The Zoom U/V parameters do not depend so much on WD because the SEM takes
care of this internally.  Imagine setting a MAG of 600 X (~ 100 µm WF) both
at high and low Z height.  The MAG determines the scale of things we see on
the display screen.  It still takes a voltage sweep of +/- 5 Volts on the
external column inputs to raster the electron beam from side to side across
the image. (just using 5 V as an example, all SEMs are different) This is
why we (Raith litho) don't see any great effect on Zoom U/V parameters as WD
changes.   Although, for good stitching results do an AlignWF at the Z
height you are writing at.


Joe.


-----Original Message-----
From: Luigi Scaccabarozzi [mailto:scaccag at stanford.edu] 
Sent: Wednesday, July 14, 2004 1:47 AM
To: Joseph Klingfus
Cc: raith at snf.Stanford.EDU; 'Kahl, Michael'; jwc at snf.Stanford.EDU
Subject: RE: Raith problem --> NO PROBLEM !!


Thanks to Joe for the explanations, but if I tried to do things exactly like
in past, can you tell me why now it is not working? I mean, what other
parameters on LEO could have possibly changed so that now the zoom exceeds
the limit?

And, if I simply decrease the MAG, what's going to happen to resolution and
other parameters?

One last question: I thought that the values of zoom-x and zoom-y depend on
the WD, as well on other parameters. I tried to change WD (from 5 to 10),
keeping all other parameters constants and the numbers don't change. Is this
normal?

I also noticed doing the align WF that in the first two scan my mark is
"reasonably" shifted from the center, whereas in the third scan is extremely
shifted (which makes zoom-y exceed the limit). What do you think about it?
Thanks for your time Gigi

On Wed, 14 Jul 2004, Joseph Klingfus wrote:

> Greetings users.
>
> There is nothing wrong with the pattern generator.
>
> A key observation is that the Magnification Display of the LEO was not 
> set to Polaroid.  This is not the first time I have heard of this 
> happening.  It is set correctly when a user account is first added, 
> but then somehow becomes set to current output device.  So far we are 
> not able to repeat how it occurs.  Please check this setting the next 
> time you log onto the SEM.
>
> Important notice concerning "zoom exceeds limits"....
> If you have never experienced this message before, then you have 
> probably always used a default WF size and have never tried to setup 
> your own WF size.  Within the Microscope Control window the 
> relationship between microscope MAG and WF size is only a very 
> "course" field setting.  The "fine tuning" is done with the AlignWF 
> procedure and the resultant field scale parameters (zoom, shift, rot.) 
> are displayed/stored in the Align WF window. There are max limits set 
> on the DACs to keep their output response linear. If "zoom exceeds 
> limits" then just decrease the MAG for the given WF size, this will 
> decrease the needed zoom value.  This message is in no way an 
> indication that there is a deficiency or problem with the tool.
>
> Joe.
>
>
> -----Original Message-----
> From: Luigi Scaccabarozzi [mailto:scaccag at stanford.edu]
> Sent: Tuesday, July 13, 2004 11:15 PM
> To: raith at snf.Stanford.EDU
> Cc: jk at raithusa.com; Kahl, Michael; jwc at snf.Stanford.EDU
> Subject: Raith problem
>
>
> Hi all,
> ryan and I have found problems today in WF alignment. The error is
> "Zoom(Y) exceeds limit". I tried resetting and shutting down computers 
> and Elphy, but no way. I tried WF align at WD 4.6 to 10 mm and the 
> numbers of WF correction are the same. It looks like that the Elphy is 
> stuck on those numbers (zoom X=1.49, zoom Y=1.52). I talked to James, 
> and he says to try again tomorrow morning (Ryan is next user) after 
> leaving the Elphy OFF for ~20 min (which I just did). If it still does 
> not work, tomorrow morning we can call him and/or Raith. If people 
> from Raith have any idea or suggestion are welcome otherwise James 
> plan is to have another Elphy shipped here tomorrow.
>
> One more thing. I noticed that the option on LEO Tools-> Preferences-> 
> SEM
> condition-> device was set to current device instead of POlaroid 545. 
> condition-> No
> idea how that could have been switched but check your account. If 
> polaroid is not selected, Align writefiled will definitely not work. 
> If you have the wrong option, select polaroid, click apply and reboot 
> both systems.
>
> Any help welcome
> Thanks
> Gigi
>




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