sem4160 problem

James Conway jwc at
Fri Aug 8 17:24:01 PDT 2008

Hello sem4160 Users:

Often it is best to ignore reports from new Users until they come up to 
speed on the system...  Like riding bicycles and playing sports, it all 
get easier and better when you train and practice your skills.

I checked out the system today and found no specific issues regarding 
resolution or brightness of the images.  Suspect that Ted Berg or 
another expert operator may have realigned the column when they used the 
tool since your last session.

We set up the column and imaged in a number of SEM modes and 
acceleration voltages and after careful column gun alignment and 
aperture adjustments we had suitable brightness in all aperture strip 

Couple points to check if you run into problems:

Best take off angle to the SE detector is between 10 and 18 mm Working 
distance WD.  Adding a little tilt on the stage can greatly increase 
brightness too.
Be sure to reduce contrast if you are observing high signal to noise in 
the image and then increase brightness.  In normal practice on initial 
view in SE SEM mode I  bring up contrast until I just start to see the 
noise speckles in the image, (i.e., dark Current of amplifier aka shot 
noise)  then reduce Contrast just slightly till the screen is no longer 
noisy, then bring up brightness to the CRT.
If you still do not have a sufficient signal then open to the next 
larger hole (smaller number) in the movable aperture strip.  Normal mode 
is aperture No 3.
Finally if you do not have enough brightness in TV view mode employ the 
slow scanning functions and you will have a much better image concurrent 
with the longer dwell times per pixel.
Lastly you can change the condenser lens setting from 12 to 10 or 8 even 
-- but with the caveat that ultimate resolution will suffer greatly.

At the end of my session today I set up the column for 10 keV 10 mm WD. 
using aperture strip no 3.
This should be fine for all but the highest resolution users working 
above 200kX.

Please give us some feedback from your sessions over the weekend by 
making a comment or if you are suffering and need assistance report a 
problem on coral for the tool. Next week we will continue to evaluate 
performance on the tool seeking solutions if we can trace to a specific 

Thank you for your interest in Ebeam Technologies here at SNF.

Have a Nice Weekend,

James Conway

d.gunning at wrote:
> Hi James,
> I'm not available this afternoon.  I heard reports from another user
> saying they had the same I don't think it was necessarily
> just the way I had set it up.  I'll try using it again over the weekend
> and then maybe I'll come along on Monday if I have time. Thanks for a
> quick reply! :o)
> Regards,
> Debbie
>> I will be in the lab after ~3:15 - 3:30 and please join me for our
>> session with trishna sengupta.
>> I will do my best to get it all set up for you!
>> All the very best,
>> James Conway
>> d.gunning at wrote:
>>> Hi James,
>>> I left a comment on coral about noise on the sem4160 - I wonder if
>>> anything is being done about it?  I really can't get a good image..and
>>> I need to use it a lot over the weekend.
>>> Regards,
>>> Debbie
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