Raith Maintenance and Testing Hours

Luigi Scaccabarozzi scaccag at stanford.edu
Tue Nov 16 10:18:00 PST 2004


Hi Ali,
of all the problems that James wants to address in the next shutdown
(which he has listed in his previous email), I can say about one of them:
the decrease in current (and consequently in speed) due to column and
aperture contamination.
I work at 10KeV, 10 um aperture, and after the last maintenance the
current was 0.025 nA. Due to contamination and use, the current
steadily decreased over the months to 0.016 nA.
That means, for example, that my job, which is already quite long to
write, takes about 50% more time to be completed (and that means hours).
Recently James realigned and optimized the column and the current went
up to 0.018 nA, but it's decreasing again. This is normal, it just happens
with use.

So, in my opinion, the raith is working fine, at least for most users, as
you say, but there are still problems (blanking artifacts that seems
to affect only a small number of users) and regular maintenance, like
change the apertures, (and maybe put two 10um apertures this time, James?)
or baking the column.
This shutdown may not be strictly necessary right now, but I don't think
it can be delayed too long, or the time you save now will be probably
spent in extra writing time.

Neverthless, I agree with you that this time James and the other
maintenance people should be extremely careful in order to avoid the
problems of the last shutdown and a prolonged downtime.

Gigi

PS: You may ask why I don't use a different aperture. I tried but with the
20 um aperture I have charging and stitching problems, so I'm stuck with 10
um.



On Tue, 16 Nov 2004, Ali Javey wrote:

> Hi James,
>
> Can you please clarify the maintenance and testing policies of the Raith?
> I have noticed that Raith will be shut down again at the end of next week
> for "maintenance".  What exactly will be done during this maintenance?
> The reason that I am asking is because at the moment Raith seems to be
> working well.  Over the weekend, I was able to write 20 nm features using
> Raith across a 10x10 mm chip.  To the best of my knowledge that is below
> the spec.  Talking to some of the other experienced users, it seems that
> they are also getting nice results.  Also by looking at the log book, I
> noticed that the experienced users have not reported any problems
> recently. May be users can reply to this message and report whether they
> have observed any problems/errors in their recent writes. My concern with
> the maintenance is that from the past, it seems that whenever the column
> is brought down for aperture or tip replacements, the system typically
> becomes unstable for few weeks with constant down time. So the question is
> when are the repairs and maintenance absolutely necessary to achieve the
> highest possible efficiency and performance for the equipment.
>
> My second concern is regarding the total number of hours that is reserved
> by yourself.  By looking at Coral, it seems that for example, you have
> signed up for 11 hours both on Tuesday and Wednesday of this week.  There
> is also a 5-hrs reservation block on Thursday and 3-hrs block on Friday.
> This adds up to a total of 30 hrs of reservation to your name just for
> this week, mainly during the prime hours.  This is for the week before the
> shutdown and at the time when Raith is heavily used. It seems that only 3
> hrs (Friday) of these reservations are for user training.  Can you please
> explain how the other hours are used?  From Coral, it seems that 22 hrs
> are used for GI and PCM (testing?).  Should there be a limit to such
> reservations?  Should the 8 hrs rule also apply to yourself. Is testing
> really necessary or can we rely on users' inputs for system qualification?
> From talking to various users from various groups, it seems that such long
> reservation hrs are an issue of concern to many users.
>
> I will appreciate your comments regarding the above issues and I really
> hope that all users can also provide their inputs through e-mails to this
> list in order for us to make the system more efficient and available to
> all.
>
> Best,
> Ali
>





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