From duygu at stanford.edu  Tue Jun  3 13:21:06 2008
From: duygu at stanford.edu (Duygu Kuzum)
Date: Tue, 03 Jun 2008 13:21:06 -0700
Subject: System up
In-Reply-To: <002c01c8c080$22115fd0$66341f70$@edu>
References: <002c01c8c080$22115fd0$66341f70$@edu>
Message-ID: <20080603132106.ite77pphyc048w0k@webmail.stanford.edu>

Hi Arash,

I talked to Yasuhiro and Shanbin. They had problems with contacting at  
low -T (80K)although devices work fine at room temperature. Low-T  
pressure is higher than expected, it is around 1e-7. Is there a leak  
in the system?


Thanks.

Quoting Arash Hazeghi <ahazeghi at stanford.edu>:

> Hi,
.
> System is up and available to users, however vacuum oil in the turbo pump is
> old and needs refill, I might steal 30min tomorrow to do this. Remember to
> fill the log sheet.
>
>
>
> Thanks,
>
> Arash
>
>
>
>
>
>
>
> ----------------------------------------------------------------------------
> ------
>
> Arash Hazeghi
>
>
>
> PhD Candidate
>
> Stanford Center for Integrated Systems
>
> CIS-X 300, 420 Via Palou Mall,
>
> Stanford, CA 94305
>
>
>
> phone: +1-650-725-0418
>
> web: http://www.stanford.edu/~ahazeghi
>
>
>
>




From ahazeghi at stanford.edu  Fri Jun  6 15:38:07 2008
From: ahazeghi at stanford.edu (Arash Hazeghi)
Date: Fri, 6 Jun 2008 15:38:07 -0700
Subject: update on cryostation
In-Reply-To: <c05dd2bf0806061513w3940cbafp58fab8f79efe78c2@mail.gmail.com>
References: <c05dd2bf0806061513w3940cbafp58fab8f79efe78c2@mail.gmail.com>
Message-ID: <010401c8c825$fdb9b350$f92d19f0$@edu>

Yasuhiro, 

Thanks for reporting the issues.

 Regarding the back diffusion I will look at the pump and contact Varian,
this shouldn't be a problem if the pump is operating correctly since we
never had this issue before. There should not be back diffusion to the
extent that you can detect oil in the chamber, if this is the case the pump
has aged and gone bad, not that we need a dry pump.  

I checked the continuity between all probes at room T and they were OK, it
is very strange that you are not getting good contact my guess is you are
not touching the pads or as you mention there is a thin layer of something
on your sample and at low voltages this may be an issue since the tips are
really soft. Per your request, I will check this again. 

Now regarding the probe tips, All four probe tips were brand new and in
perfect shape when I replaced them just last week. I will look in the
logbook to see who used them. This is becoming a major issue, I cannot
replace the probe tips every week and our group will not pay for it.  Per
prof. Wong's suggestion from now on, whoever breaks the tips and don't
report it will not only have to buy new tips but will also be suspended from
the system for two weeks. No exceptions. 

Please be considerate when lowering and raising the tips. Never keep the
tips contacted to the sample or in close proximity before pumping down or
cooling. As the chamber goes to high vacuum the bellows  are stressed and
bow a little bit, as a result tips that are close to surface will crush or
may even run into each other. Position and lower the tips only when pressure
and temperature have been stabilized. Never lean on the table, yank the
cables or subject the system to mechanical shock when tips are in contact.
If users operate the probes according to the training these tips should last
for months.

 

Thank you all for your cooperation ,

Arash

 

 

----------------------------------------------------------------------------
------

Arash Hazeghi

 

PhD Candidate

Stanford Center for Integrated Systems

CIS-X 300, 420 Via Palou Mall, 

Stanford, CA 94305

 

phone: +1-650-725-0418

web: http://www.stanford.edu/~ahazeghi

 

 

 

   

 

From: yoshima73 at gmail.com [mailto:yoshima73 at gmail.com] On Behalf Of Yasuhiro
Oshima
Sent: Friday, June 06, 2008 3:13 PM
To: Arash Hazeghi; Duygu Kuzum; shanbin at stanford.edu
Subject: update on cryostation

 

Hi all,

  Now the cyostation working at 77K very well. As Shanbin pointed out, it
seems that we had a contact issue between needle and metal pad due to very
hard condensed liquid (maybe vacuum oil back diffused into chamber). I just
replaced old vacuum oil of rotary pump. It turn into yellowish color
gradually. It seems to be important to replace it like once in 3 months.
Thanks for good suggestion, Arash! Another information are bellow. 

 

- new oil and container for old oil are near the cryostation. (Arash, could
you move to good position?)

- I still see some liquid (solid. maybe oil) on my samples. They look hazy.

- if you'd like to solve this problem permanently, I would recommend to
replace oil pump with diaphragm pump (this is dry).

- probe tips 3 & 4 are not working (it seems completely isolated). Arash,
please take a look at it! 

- probe tips 1 & 2 are bent and not comfortable.(It is not me...)

 

Best,

  Yasuhiro


-- 
Yasuhiro Oshima
408-398-4753 (cell) 

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From yoshima at stanford.edu  Fri Jun  6 16:33:43 2008
From: yoshima at stanford.edu (Yasuhiro Oshima)
Date: Fri, 6 Jun 2008 16:33:43 -0700
Subject: update on cryostation
In-Reply-To: <010401c8c825$fdb9b350$f92d19f0$@edu>
References: <c05dd2bf0806061513w3940cbafp58fab8f79efe78c2@mail.gmail.com>
	 <010401c8c825$fdb9b350$f92d19f0$@edu>
Message-ID: <c05dd2bf0806061633l13e2dde9qdce034484233e793@mail.gmail.com>

Hi Arash,
  I checked all the tips' continuity before cool it down and found 3& 4 were
strange. So it happened without oil condensation.

  As for oil back diffusion... The design of this vacuum system, including
automatic pump down/vent sequence is not good. There are no isolation valves
and this sequence supply the vent nitrogen from downstream of TMP into the
chamber right after stopping pump. Once these back diffused oil accumulate
in the chamber, it is very difficult to remove, just increase gradually. My
another suggestion is that to put valves between chamber/TMP and TMP/rotary
pump, and nitrogen line directly into the chamber, though it may make the
procedure complicated.
  Actually, we have seen hazy surface on our sample every time. But I did
not realized that this may behave as insulator.

Thanks,
  Yasuhiro
2008/6/6 Arash Hazeghi <ahazeghi at stanford.edu>:

>  Yasuhiro,
>
> Thanks for reporting the issues.
>
>  Regarding the back diffusion I will look at the pump and contact Varian,
> this shouldn't be a problem if the pump is operating correctly since we
> never had this issue before. There should not be back diffusion to the
> extent that you can detect oil in the chamber, if this is the case the pump
> has aged and gone bad, not that we need a dry pump.
>
> I checked the continuity between all probes at room T and they were OK, it
> is very strange that you are not getting good contact my guess is you are
> not touching the pads or as you mention there is a thin layer of something
> on your sample and at low voltages this may be an issue since the tips are
> really soft. Per your request, I will check this again.
>
> Now regarding the probe tips,* All four probe tips* were brand new and in
> *perfect* shape when I replaced them just last week. I will look in the
> logbook to see who used them. This is becoming a major issue, I cannot
> replace the probe tips every week and our group will not pay for it.  Per
> prof. Wong's suggestion from now on, whoever breaks the tips and don't
> report it will not only have to buy new tips but will also be suspended from
> the system for two weeks. No exceptions.
>
> Please be considerate when lowering and raising the tips. Never keep the
> tips contacted to the sample or in close proximity before pumping down or
> cooling. As the chamber goes to high vacuum the bellows  are stressed and
> bow a little bit, as a result tips that are close to surface will crush or
> may even run into each other. Position and lower the tips only when pressure
> and temperature have been stabilized. Never lean on the table, yank the
> cables or subject the system to mechanical shock when tips are in contact.
> If users operate the probes according to the training these tips should last
> for months.
>
>
>
> Thank you all for your cooperation ,
>
> Arash
>
>
>
>
>
>
> ----------------------------------------------------------------------------------
>
> Arash Hazeghi
>
>
>
> PhD Candidate
>
> Stanford Center for Integrated Systems
>
> CIS-X 300, 420 Via Palou Mall,
>
> Stanford, CA 94305
>
>
>
> phone: +1-650-725-0418
>
> web: http://www.stanford.edu/~ahazeghi
>
>
>
>
>
>
>
>
>
>
>
> *From:* yoshima73 at gmail.com [mailto:yoshima73 at gmail.com] *On Behalf Of *Yasuhiro
> Oshima
> *Sent:* Friday, June 06, 2008 3:13 PM
> *To:* Arash Hazeghi; Duygu Kuzum; shanbin at stanford.edu
> *Subject:* update on cryostation
>
>
>
> Hi all,
>
>   Now the cyostation working at 77K very well. As Shanbin pointed out, it
> seems that we had a contact issue between needle and metal pad due to very
> hard condensed liquid (maybe vacuum oil back diffused into chamber). I just
> replaced old vacuum oil of rotary pump. It turn into yellowish color
> gradually. It seems to be important to replace it like once in 3 months.
> Thanks for good suggestion, Arash! Another information are bellow.
>
>
>
> - new oil and container for old oil are near the cryostation. (Arash, could
> you move to good position?)
>
> - I still see some liquid (solid. maybe oil) on my samples. They look hazy.
>
> - if you'd like to solve this problem permanently, I would recommend to
> replace oil pump with diaphragm pump (this is dry).
>
> - probe tips 3 & 4 are not working (it seems completely isolated). Arash,
> please take a look at it!
>
> - probe tips 1 & 2 are bent and not comfortable.(It is not me...)
>
>
>
> Best,
>
>   Yasuhiro
>
>
> --
> Yasuhiro Oshima
> 408-398-4753 (cell)
>



-- 
Yasuhiro Oshima
Visiting Scholar
Prof. McIntyre Gr.
Materials Science and Engineering
Stanford University
650-725-3458
408-398-4753 (cell)
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From duygu at stanford.edu  Fri Jun  6 16:41:09 2008
From: duygu at stanford.edu (Duygu Kuzum)
Date: Fri, 06 Jun 2008 16:41:09 -0700
Subject: update on cryostation
In-Reply-To: <c05dd2bf0806061633l13e2dde9qdce034484233e793@mail.gmail.com>
References: <c05dd2bf0806061513w3940cbafp58fab8f79efe78c2@mail.gmail.com>
	<010401c8c825$fdb9b350$f92d19f0$@edu>
	<c05dd2bf0806061633l13e2dde9qdce034484233e793@mail.gmail.com>
Message-ID: <20080606164109.mf6hive2skkc0wk8@webmail.stanford.edu>

I also observed that last year too.Probing at low temperature was very  
difficult.Sometimes I got bad contact causing a lot of noise.Sometimes  
I couldnt get contact.

Thanks Yasuhiro,

Duygu

Quoting Yasuhiro Oshima <yoshima at stanford.edu>:

> Hi Arash,
>   I checked all the tips' continuity before cool it down and found 3& 4 were
> strange. So it happened without oil condensation.
>
>   As for oil back diffusion... The design of this vacuum system, including
> automatic pump down/vent sequence is not good. There are no isolation valves
> and this sequence supply the vent nitrogen from downstream of TMP into the
> chamber right after stopping pump. Once these back diffused oil accumulate
> in the chamber, it is very difficult to remove, just increase gradually. My
> another suggestion is that to put valves between chamber/TMP and TMP/rotary
> pump, and nitrogen line directly into the chamber, though it may make the
> procedure complicated.
>   Actually, we have seen hazy surface on our sample every time. But I did
> not realized that this may behave as insulator.
>
> Thanks,
>   Yasuhiro
> 2008/6/6 Arash Hazeghi <ahazeghi at stanford.edu>:
>
>>  Yasuhiro,
>>
>> Thanks for reporting the issues.
>>
>>  Regarding the back diffusion I will look at the pump and contact Varian,
>> this shouldn't be a problem if the pump is operating correctly since we
>> never had this issue before. There should not be back diffusion to the
>> extent that you can detect oil in the chamber, if this is the case the pump
>> has aged and gone bad, not that we need a dry pump.
>>
>> I checked the continuity between all probes at room T and they were OK, it
>> is very strange that you are not getting good contact my guess is you are
>> not touching the pads or as you mention there is a thin layer of something
>> on your sample and at low voltages this may be an issue since the tips are
>> really soft. Per your request, I will check this again.
>>
>> Now regarding the probe tips,* All four probe tips* were brand new and in
>> *perfect* shape when I replaced them just last week. I will look in the
>> logbook to see who used them. This is becoming a major issue, I cannot
>> replace the probe tips every week and our group will not pay for it.  Per
>> prof. Wong's suggestion from now on, whoever breaks the tips and don't
>> report it will not only have to buy new tips but will also be suspended from
>> the system for two weeks. No exceptions.
>>
>> Please be considerate when lowering and raising the tips. Never keep the
>> tips contacted to the sample or in close proximity before pumping down or
>> cooling. As the chamber goes to high vacuum the bellows  are stressed and
>> bow a little bit, as a result tips that are close to surface will crush or
>> may even run into each other. Position and lower the tips only when pressure
>> and temperature have been stabilized. Never lean on the table, yank the
>> cables or subject the system to mechanical shock when tips are in contact.
>> If users operate the probes according to the training these tips should last
>> for months.
>>
>>
>>
>> Thank you all for your cooperation ,
>>
>> Arash
>>
>>
>>
>>
>>
>>
>> ----------------------------------------------------------------------------------
>>
>> Arash Hazeghi
>>
>>
>>
>> PhD Candidate
>>
>> Stanford Center for Integrated Systems
>>
>> CIS-X 300, 420 Via Palou Mall,
>>
>> Stanford, CA 94305
>>
>>
>>
>> phone: +1-650-725-0418
>>
>> web: http://www.stanford.edu/~ahazeghi
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> *From:* yoshima73 at gmail.com [mailto:yoshima73 at gmail.com] *On Behalf  
>>  Of *Yasuhiro
>> Oshima
>> *Sent:* Friday, June 06, 2008 3:13 PM
>> *To:* Arash Hazeghi; Duygu Kuzum; shanbin at stanford.edu
>> *Subject:* update on cryostation
>>
>>
>>
>> Hi all,
>>
>>   Now the cyostation working at 77K very well. As Shanbin pointed out, it
>> seems that we had a contact issue between needle and metal pad due to very
>> hard condensed liquid (maybe vacuum oil back diffused into chamber). I just
>> replaced old vacuum oil of rotary pump. It turn into yellowish color
>> gradually. It seems to be important to replace it like once in 3 months.
>> Thanks for good suggestion, Arash! Another information are bellow.
>>
>>
>>
>> - new oil and container for old oil are near the cryostation. (Arash, could
>> you move to good position?)
>>
>> - I still see some liquid (solid. maybe oil) on my samples. They look hazy.
>>
>> - if you'd like to solve this problem permanently, I would recommend to
>> replace oil pump with diaphragm pump (this is dry).
>>
>> - probe tips 3 & 4 are not working (it seems completely isolated). Arash,
>> please take a look at it!
>>
>> - probe tips 1 & 2 are bent and not comfortable.(It is not me...)
>>
>>
>>
>> Best,
>>
>>   Yasuhiro
>>
>>
>> --
>> Yasuhiro Oshima
>> 408-398-4753 (cell)
>>
>
>
>
> --
> Yasuhiro Oshima
> Visiting Scholar
> Prof. McIntyre Gr.
> Materials Science and Engineering
> Stanford University
> 650-725-3458
> 408-398-4753 (cell)
>




From mcvittie at cis.Stanford.EDU  Fri Jun  6 17:55:59 2008
From: mcvittie at cis.Stanford.EDU (Jim McVittie)
Date: Fri, 6 Jun 2008 17:55:59 -0700 (PDT)
Subject: update on cryostation
In-Reply-To: <20080606164109.mf6hive2skkc0wk8@webmail.stanford.edu>
Message-ID: <Pine.LNX.4.44.0806061753220.25206-100000@cis.Stanford.EDU>

Arash,

I agree with Yasuhiro that the vacuum system is a poor design in terms of
oil backstreaming. I suspect that the vendor subsituted a cheaper pump to
get the cost when he was selling us the system.

	Jim  

On Fri, 6 Jun 2008, Duygu Kuzum wrote:

> I also observed that last year too.Probing at low temperature was very  
> difficult.Sometimes I got bad contact causing a lot of noise.Sometimes  
> I couldnt get contact.
> 
> Thanks Yasuhiro,
> 
> Duygu
> 
> Quoting Yasuhiro Oshima <yoshima at stanford.edu>:
> 
> > Hi Arash,
> >   I checked all the tips' continuity before cool it down and found 3& 4 were
> > strange. So it happened without oil condensation.
> >
> >   As for oil back diffusion... The design of this vacuum system, including
> > automatic pump down/vent sequence is not good. There are no isolation valves
> > and this sequence supply the vent nitrogen from downstream of TMP into the
> > chamber right after stopping pump. Once these back diffused oil accumulate
> > in the chamber, it is very difficult to remove, just increase gradually. My
> > another suggestion is that to put valves between chamber/TMP and TMP/rotary
> > pump, and nitrogen line directly into the chamber, though it may make the
> > procedure complicated.
> >   Actually, we have seen hazy surface on our sample every time. But I did
> > not realized that this may behave as insulator.
> >
> > Thanks,
> >   Yasuhiro
> > 2008/6/6 Arash Hazeghi <ahazeghi at stanford.edu>:
> >
> >>  Yasuhiro,
> >>
> >> Thanks for reporting the issues.
> >>
> >>  Regarding the back diffusion I will look at the pump and contact Varian,
> >> this shouldn't be a problem if the pump is operating correctly since we
> >> never had this issue before. There should not be back diffusion to the
> >> extent that you can detect oil in the chamber, if this is the case the pump
> >> has aged and gone bad, not that we need a dry pump.
> >>
> >> I checked the continuity between all probes at room T and they were OK, it
> >> is very strange that you are not getting good contact my guess is you are
> >> not touching the pads or as you mention there is a thin layer of something
> >> on your sample and at low voltages this may be an issue since the tips are
> >> really soft. Per your request, I will check this again.
> >>
> >> Now regarding the probe tips,* All four probe tips* were brand new and in
> >> *perfect* shape when I replaced them just last week. I will look in the
> >> logbook to see who used them. This is becoming a major issue, I cannot
> >> replace the probe tips every week and our group will not pay for it.  Per
> >> prof. Wong's suggestion from now on, whoever breaks the tips and don't
> >> report it will not only have to buy new tips but will also be suspended from
> >> the system for two weeks. No exceptions.
> >>
> >> Please be considerate when lowering and raising the tips. Never keep the
> >> tips contacted to the sample or in close proximity before pumping down or
> >> cooling. As the chamber goes to high vacuum the bellows  are stressed and
> >> bow a little bit, as a result tips that are close to surface will crush or
> >> may even run into each other. Position and lower the tips only when pressure
> >> and temperature have been stabilized. Never lean on the table, yank the
> >> cables or subject the system to mechanical shock when tips are in contact.
> >> If users operate the probes according to the training these tips should last
> >> for months.
> >>
> >>
> >>
> >> Thank you all for your cooperation ,
> >>
> >> Arash
> >>
> >>
> >>
> >>
> >>
> >>
> >> ----------------------------------------------------------------------------------
> >>
> >> Arash Hazeghi
> >>
> >>
> >>
> >> PhD Candidate
> >>
> >> Stanford Center for Integrated Systems
> >>
> >> CIS-X 300, 420 Via Palou Mall,
> >>
> >> Stanford, CA 94305
> >>
> >>
> >>
> >> phone: +1-650-725-0418
> >>
> >> web: http://www.stanford.edu/~ahazeghi
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >> *From:* yoshima73 at gmail.com [mailto:yoshima73 at gmail.com] *On Behalf  
> >>  Of *Yasuhiro
> >> Oshima
> >> *Sent:* Friday, June 06, 2008 3:13 PM
> >> *To:* Arash Hazeghi; Duygu Kuzum; shanbin at stanford.edu
> >> *Subject:* update on cryostation
> >>
> >>
> >>
> >> Hi all,
> >>
> >>   Now the cyostation working at 77K very well. As Shanbin pointed out, it
> >> seems that we had a contact issue between needle and metal pad due to very
> >> hard condensed liquid (maybe vacuum oil back diffused into chamber). I just
> >> replaced old vacuum oil of rotary pump. It turn into yellowish color
> >> gradually. It seems to be important to replace it like once in 3 months.
> >> Thanks for good suggestion, Arash! Another information are bellow.
> >>
> >>
> >>
> >> - new oil and container for old oil are near the cryostation. (Arash, could
> >> you move to good position?)
> >>
> >> - I still see some liquid (solid. maybe oil) on my samples. They look hazy.
> >>
> >> - if you'd like to solve this problem permanently, I would recommend to
> >> replace oil pump with diaphragm pump (this is dry).
> >>
> >> - probe tips 3 & 4 are not working (it seems completely isolated). Arash,
> >> please take a look at it!
> >>
> >> - probe tips 1 & 2 are bent and not comfortable.(It is not me...)
> >>
> >>
> >>
> >> Best,
> >>
> >>   Yasuhiro
> >>
> >>
> >> --
> >> Yasuhiro Oshima
> >> 408-398-4753 (cell)
> >>
> >
> >
> >
> > --
> > Yasuhiro Oshima
> > Visiting Scholar
> > Prof. McIntyre Gr.
> > Materials Science and Engineering
> > Stanford University
> > 650-725-3458
> > 408-398-4753 (cell)
> >
> 
> 
> 

-- 
--------------------------------------------------------------
Jim McVittie, Ph.D.    			Senior Research Scientist 
Allen Center for Integrated Systems     Electrical Engineering
Stanford University             	jmcvittie at stanford.edu
Rm. 336, 330 Serra Mall			Fax: (650) 723-4659
Stanford, CA 94305-4075			Tel: (650) 725-3640




From yoshima at stanford.edu  Sun Jun  8 00:32:06 2008
From: yoshima at stanford.edu (Yasuhiro Oshima)
Date: Sun, 8 Jun 2008 00:32:06 -0700
Subject: update on cryostation
In-Reply-To: <Pine.LNX.4.44.0806061753220.25206-100000@cis.Stanford.EDU>
References: <20080606164109.mf6hive2skkc0wk8@webmail.stanford.edu>
	 <Pine.LNX.4.44.0806061753220.25206-100000@cis.Stanford.EDU>
Message-ID: <c05dd2bf0806080032v24f8b44bk1f59993e119816be@mail.gmail.com>

Hi Jim,
  Thank you for your comment.

Hi Arash,
  By the way, tips 1&2 are bent but still usable. Tips 3&4 have good shape
but I couldn't use for their discontinuity.

Yasuhiro

2008/6/6 Jim McVittie <mcvittie at cis.stanford.edu>:

> Arash,
>
> I agree with Yasuhiro that the vacuum system is a poor design in terms of
> oil backstreaming. I suspect that the vendor subsituted a cheaper pump to
> get the cost when he was selling us the system.
>
>        Jim
>
> On Fri, 6 Jun 2008, Duygu Kuzum wrote:
>
> > I also observed that last year too.Probing at low temperature was very
> > difficult.Sometimes I got bad contact causing a lot of noise.Sometimes
> > I couldnt get contact.
> >
> > Thanks Yasuhiro,
> >
> > Duygu
> >
> > Quoting Yasuhiro Oshima <yoshima at stanford.edu>:
> >
> > > Hi Arash,
> > >   I checked all the tips' continuity before cool it down and found 3& 4
> were
> > > strange. So it happened without oil condensation.
> > >
> > >   As for oil back diffusion... The design of this vacuum system,
> including
> > > automatic pump down/vent sequence is not good. There are no isolation
> valves
> > > and this sequence supply the vent nitrogen from downstream of TMP into
> the
> > > chamber right after stopping pump. Once these back diffused oil
> accumulate
> > > in the chamber, it is very difficult to remove, just increase
> gradually. My
> > > another suggestion is that to put valves between chamber/TMP and
> TMP/rotary
> > > pump, and nitrogen line directly into the chamber, though it may make
> the
> > > procedure complicated.
> > >   Actually, we have seen hazy surface on our sample every time. But I
> did
> > > not realized that this may behave as insulator.
> > >
> > > Thanks,
> > >   Yasuhiro
> > > 2008/6/6 Arash Hazeghi <ahazeghi at stanford.edu>:
> > >
> > >>  Yasuhiro,
> > >>
> > >> Thanks for reporting the issues.
> > >>
> > >>  Regarding the back diffusion I will look at the pump and contact
> Varian,
> > >> this shouldn't be a problem if the pump is operating correctly since
> we
> > >> never had this issue before. There should not be back diffusion to the
> > >> extent that you can detect oil in the chamber, if this is the case the
> pump
> > >> has aged and gone bad, not that we need a dry pump.
> > >>
> > >> I checked the continuity between all probes at room T and they were
> OK, it
> > >> is very strange that you are not getting good contact my guess is you
> are
> > >> not touching the pads or as you mention there is a thin layer of
> something
> > >> on your sample and at low voltages this may be an issue since the tips
> are
> > >> really soft. Per your request, I will check this again.
> > >>
> > >> Now regarding the probe tips,* All four probe tips* were brand new and
> in
> > >> *perfect* shape when I replaced them just last week. I will look in
> the
> > >> logbook to see who used them. This is becoming a major issue, I cannot
> > >> replace the probe tips every week and our group will not pay for it.
>  Per
> > >> prof. Wong's suggestion from now on, whoever breaks the tips and don't
> > >> report it will not only have to buy new tips but will also be
> suspended from
> > >> the system for two weeks. No exceptions.
> > >>
> > >> Please be considerate when lowering and raising the tips. Never keep
> the
> > >> tips contacted to the sample or in close proximity before pumping down
> or
> > >> cooling. As the chamber goes to high vacuum the bellows  are stressed
> and
> > >> bow a little bit, as a result tips that are close to surface will
> crush or
> > >> may even run into each other. Position and lower the tips only when
> pressure
> > >> and temperature have been stabilized. Never lean on the table, yank
> the
> > >> cables or subject the system to mechanical shock when tips are in
> contact.
> > >> If users operate the probes according to the training these tips
> should last
> > >> for months.
> > >>
> > >>
> > >>
> > >> Thank you all for your cooperation ,
> > >>
> > >> Arash
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> ----------------------------------------------------------------------------------
> > >>
> > >> Arash Hazeghi
> > >>
> > >>
> > >>
> > >> PhD Candidate
> > >>
> > >> Stanford Center for Integrated Systems
> > >>
> > >> CIS-X 300, 420 Via Palou Mall,
> > >>
> > >> Stanford, CA 94305
> > >>
> > >>
> > >>
> > >> phone: +1-650-725-0418
> > >>
> > >> web: http://www.stanford.edu/~ahazeghi
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >> *From:* yoshima73 at gmail.com [mailto:yoshima73 at gmail.com] *On Behalf
> > >>  Of *Yasuhiro
> > >> Oshima
> > >> *Sent:* Friday, June 06, 2008 3:13 PM
> > >> *To:* Arash Hazeghi; Duygu Kuzum; shanbin at stanford.edu
> > >> *Subject:* update on cryostation
> > >>
> > >>
> > >>
> > >> Hi all,
> > >>
> > >>   Now the cyostation working at 77K very well. As Shanbin pointed out,
> it
> > >> seems that we had a contact issue between needle and metal pad due to
> very
> > >> hard condensed liquid (maybe vacuum oil back diffused into chamber). I
> just
> > >> replaced old vacuum oil of rotary pump. It turn into yellowish color
> > >> gradually. It seems to be important to replace it like once in 3
> months.
> > >> Thanks for good suggestion, Arash! Another information are bellow.
> > >>
> > >>
> > >>
> > >> - new oil and container for old oil are near the cryostation. (Arash,
> could
> > >> you move to good position?)
> > >>
> > >> - I still see some liquid (solid. maybe oil) on my samples. They look
> hazy.
> > >>
> > >> - if you'd like to solve this problem permanently, I would recommend
> to
> > >> replace oil pump with diaphragm pump (this is dry).
> > >>
> > >> - probe tips 3 & 4 are not working (it seems completely isolated).
> Arash,
> > >> please take a look at it!
> > >>
> > >> - probe tips 1 & 2 are bent and not comfortable.(It is not me...)
> > >>
> > >>
> > >>
> > >> Best,
> > >>
> > >>   Yasuhiro
> > >>
> > >>
> > >> --
> > >> Yasuhiro Oshima
> > >> 408-398-4753 (cell)
> > >>
> > >
> > >
> > >
> > > --
> > > Yasuhiro Oshima
> > > Visiting Scholar
> > > Prof. McIntyre Gr.
> > > Materials Science and Engineering
> > > Stanford University
> > > 650-725-3458
> > > 408-398-4753 (cell)
> > >
> >
> >
> >
>
> --
> --------------------------------------------------------------
> Jim McVittie, Ph.D.                     Senior Research Scientist
> Allen Center for Integrated Systems     Electrical Engineering
> Stanford University                     jmcvittie at stanford.edu
> Rm. 336, 330 Serra Mall                 Fax: (650) 723-4659
> Stanford, CA 94305-4075                 Tel: (650) 725-3640
>
>
>


-- 
Yasuhiro Oshima
Visiting Scholar
Prof. McIntyre Gr.
Materials Science and Engineering
Stanford University
650-725-3458
408-398-4753 (cell)
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