From shott at stanford.edu  Tue Apr  6 17:08:11 2010
From: shott at stanford.edu (John Shott)
Date: Tue, 06 Apr 2010 17:08:11 -0700
Subject: MRC Update ....
Message-ID: <4BBBCCEB.6010502@stanford.edu>

MRC Community:

This afternoon we received our spare Santovac diffusion fluid and 
checked both the level and color (which is normally clear) of the 
fluid.  We found it to be significantly low but otherwise looked pretty 
good.  As a result, rather than dropping the diffusion pump, it seems 
more reasonable to fill it to the proper level.  We have added about 300 
cc of Santovac5 ... the full charge amount is only 500 cc so we were 
well down.

The only trouble .... I can't seem to get the diffusion pump back on.  
Because I didn't turn it off, I don't know if there are any tricks.
Hopefully, Jim Kruger or someone else will be able to figure this out 
and get the heater back on again.  It is roughed down .... but needs the 
pump heater to come on.  I did check the overtemp switch and it 
initially seemed to be an open circuit.  After a bit of fiddling, to 
read 0 ohms.  However, even after that, I measured no voltage at the 
plug, so wonder whether there is some sort of upstream interlock on the 
tool.

Of course the heater will need to be on before pumping can be tested.  
Beccause the heater is not on, I don't want to clear the shutdown ... I 
will be out for 2-3 hours, but if anyone (Jim Kruger, Cesar, or Eric, 
for example) can get the heater back on, the shutdown can be cleared for 
vacuum testing.

Thanks,

John



From shott at stanford.edu  Thu Apr  8 21:14:26 2010
From: shott at stanford.edu (John Shott)
Date: Thu, 08 Apr 2010 21:14:26 -0700
Subject: Pumping system operational again ....
Message-ID: <4BBEA9A2.8070406@stanford.edu>

MRC Community:

After a true team effort, I believe that the MRC diffusion pump woes are 
behind us.  This all began with Jim Kruger's discovery a few days ago 
that the foreline/roughing valve had been left in the intermediate 
"don't pump on anything" position ... followed shortly by observed poor 
pumping performance.

In the process we found the following problems:

1. The pump oil in the diffusion pump was quite low.  We resolve this 
with the addition of 300 cc (approximately) out of a total charge of 500 
cc of Santovac 5 diffusion pump oil.

2. The heater element was found to be an open circuit.  After taking it 
apart there was evidence that it had shorted to the pump body at some 
point ...

3. The shorting action likely blew the fuse of one of the two power legs 
of the 208 VAC power.  Initially I had a hard time tracking this down 
because the body of the fuse holder, rather being in the main fuse 
panel, is tucked into the body of the power distribution section.

4. After all of this, I was unable to get the main AC power back to the 
diffusion pumps ... but, fortunately, Eric and Jim Kruger managed to get 
the power turned back on ... and it appears as if the DP heater is 
working properly.

Mihir Tendulkar is running the system now and will hopefully report his 
results or any anomalous behavior.

Please check things carefully before running this system on important 
samples.

I'd like to thank both Jim Kruger and Eric Perozziello for their help in 
getting this problem resolved.  I'd also like to apologize to those that 
have been inconvenienced by the delay in getting the system operational 
... I fear that I am not as quick at effecting repairs of this type as 
the regulars on the job.

Thank you for your continued support,

John



From mihirt at stanford.edu  Fri Apr  9 01:58:24 2010
From: mihirt at stanford.edu (Mihir Tendulkar)
Date: Fri, 9 Apr 2010 01:58:24 -0700 (PDT)
Subject: Pumping system operational again ....
In-Reply-To: <4BBEA9A2.8070406@stanford.edu>
Message-ID: <18708571.1539681270803504725.JavaMail.root@zm01.stanford.edu>


----- "John Shott" <shott at stanford.edu> wrote:

> Mihir Tendulkar is running the system now and will hopefully report
> his results or any anomalous behavior.

The pumping times were normal, although the gauge is not zeroed properly (offset of 1). I took that into account when running my test wafers, and I found that my etch rates are normal.  

The only anomaly I noticed is that Freon 23 occasionally fluctuates and triggers the Deviation light. For my short etch (1.5 min), this wasn't a big concern. It only happened during a couple of wafers. Someone using F-23 in a longer etch may want to keep an eye on the MFC reading. 

I noted this as a comment on Coral. 

Thanks to Jim, Eric, and John for getting it running again! 

-- 
Mihir Tendulkar
Applied Physics PhD Candidate
Nishi Group, Stanford University


From mihirt at stanford.edu  Tue Apr 13 20:54:28 2010
From: mihirt at stanford.edu (Mihir Tendulkar)
Date: Tue, 13 Apr 2010 20:54:28 -0700 (PDT)
Subject: Quartz block missing - has anyone seen it?
Message-ID: <1846849368.2456001271217268771.JavaMail.root@zm01.stanford.edu>

Hi all,

The last quartz block in the MRC walked off between Saturday and today. I use it to brace my wafers against the vacuum, so I'd really like to use it. If you borrowed it, please let me know where it is. 

-- 
Mihir Tendulkar
Applied Physics PhD Candidate
Nishi Group, Stanford University


From jimkruger at yahoo.com  Tue Apr 13 21:03:45 2010
From: jimkruger at yahoo.com (jim kruger)
Date: Tue, 13 Apr 2010 21:03:45 -0700 (PDT)
Subject: Quartz block missing - has anyone seen it?
In-Reply-To: <1846849368.2456001271217268771.JavaMail.root@zm01.stanford.edu>
Message-ID: <295866.65517.qm@web38908.mail.mud.yahoo.com>

I looked for it but did not see it on Monday afternoon.
Perhaps ask the maintenance guys ( Ted?, Ray?) if there might be a suitable quartz scrapor two from the old furnace glassware.jim

--- On Tue, 4/13/10, Mihir Tendulkar <mihirt at stanford.edu> wrote:

From: Mihir Tendulkar <mihirt at stanford.edu>
Subject: Quartz block missing - has anyone seen it?
To: "mrc" <mrc at snf.stanford.edu>
Date: Tuesday, April 13, 2010, 8:54 PM

Hi all,

The last quartz block in the MRC walked off between Saturday and today. I use it to brace my wafers against the vacuum, so I'd really like to use it. If you borrowed it, please let me know where it is. 

-- 
Mihir Tendulkar
Applied Physics PhD Candidate
Nishi Group, Stanford University



      
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