Comment from CMP manufacture

Ed Myers edmyers at stanford.edu
Mon Apr 13 07:52:22 PDT 2009


All,

Apparently, we have good timing as the manufactures of the CMP group 
will be in the bay area.

Regards,
Ed

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>From: "Haedo Jeong" <hdjeong at pusan.ac.kr>
>To: "'Ed Myers'" <edmyers at stanford.edu>
>Subject: RE: Re: Wafer broken
>Date: Sat, 11 Apr 2009 22:53:22 +0900
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>
>Hi Ed,
>
>I hope this message finds you well.
>Based on your information, I discussed with our members.
>What I can comment to you is, to make the pressure of vacuum regulator lower
>and to explain how to chuck a wafer.
>Hopefully, Dr. Kihyun Park of GnP Technology who stay in Berkeley, will
>contact you or Sangbeom Kim and visit SNF next week.
>Fortunately, I will stay in San Fransisco to attend on MRS 2009 Spring
>meeting whole next week and have to leave tomorrow here. Please let me know
>if you need my help.
>
>Thank you in advance.
>Haedo
>-----Original Message-----
>From: Ed Myers [mailto:edmyers at stanford.edu]
>Sent: Saturday, April 11, 2009 6:49 AM
>To: Haedo Jeong
>Subject: Fwd: Re: Wafer broken
>
>Haedo,
>
>Here is some more information exchange going on between our lab
>members.  I have included the following excerpt along with continuing
>discussion from an earlier email.
>
>Regards,
>Ed
>
>At 01:32 PM 4/10/2009, you wrote:
>  >broke 4 out of 8 wafers during chucking. This may be my
>  >inexperience, but the membrane bulged out, and then after pressing
>  >'chucking' button vacuum pulls the wafer in, and any slight
>  >misalignment of the wafer from the ring caused a crack.
>
>
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> >Date: Fri, 10 Apr 2009 14:31:17 -0700 (PDT)
> >From: Chong Xie <chongxie at stanford.edu>
> >To: Christopher McGuinness <cmcg at snf.stanford.edu>
> >Cc: SangBum Kim <kimsangb at stanford.edu>, cmp at snf.stanford.edu
> >Subject: Re: Wafer broken
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> >X-Authenticated-User: chongxie at stanford.edu
> >
> >Thanks for the information.
> >My wafers might be weakened by the trenches significantly. At least
> >they can gather the strain. I didn't see where the fracture
> >occurred, since the wafers were broken into small pieces.
> >I agree the the pick up process is rather violent. It's mostly
> >likely that's when it breaks the wafers. It would be nice if it can
> >be turned off.
> >
> >
> >chong
> >
> >----- Original Message -----
> >From: "Christopher McGuinness" <cmcg at snf.stanford.edu>
> >To: "Chong Xie" <chongxie at stanford.edu>
> >Cc: "SangBum Kim" <kimsangb at stanford.edu>, cmp at snf.stanford.edu
> >Sent: Friday, April 10, 2009 1:59:29 PM GMT -08:00 US/Canada Pacific
> >Subject: Re: Wafer broken
> >
> >This is strange. I've used the CMP many times and have never had a
> >wafer break on me. The only things I can think that would cause this
> >discrepancy are:
> >1) We load the wafers differently. I don't see how this can be the
> >case though, as it is pretty straightforward...
> >2) The tool parameters are different. Again, I run the tool at the
> >standard settings, so unless something has degraded or changed since
> >I last used it this would not seem to be the case.
> >3) There is something about our wafers that is different. I polish
> >wafers with a .6um thick layer of oxide, patterned and filled with a
> >similarly thick layer of poly. There is very little surface topology
> >on my wafers and I polish them down to the surface of the oxide, so
> >basically it is planar the whole time. Could the 2um trench you
> >mentioned be weakening the wafer? Does the fracture occur along the trench?
> >
> >I have also noticed that when the tool turns the vaccuum on again to
> >pick up the wafer it is a rather violent thump. I wonder if this
> >vaccuum turn on step could be looked at and adjusted to be less
> >violent. Or just skipped entirely so you pick your wafer up off the pad....
> >
> >Sorry to hear about all the destruction. That must be frustrating.
> >
> >-Chris
> >
> >
> >
> >
> >
> >On Fri, Apr 10, 2009 at 1:48 PM, Chong Xie < chongxie at stanford.edu > wrote:
> >
> >
> >Thanks a lot! That's very likely the case. I will try turning off
> >the vacuum next time.
> >
> >chong
> >
> >
> >
> >----- Original Message -----
> >From: "SangBum Kim" < kimsangb at stanford.edu >
> >To: "Chong Xie" < chongxie at stanford.edu >
> >Cc: cmp at snf.stanford.edu
> >Sent: Friday, April 10, 2009 12:33:34 PM GMT -08:00 US/Canada Pacific
> >Subject: Re: Wafer broken
> >
> >Hi Chong,
> >
> >Do you know during which CMP step your wafer gets broken? In my
> >case, most of my broken wafers actaully got broken when it is picked
> >back up again by the head after it is done polishing. If that is the
> >case for you, you can avoid that by turning off the vacuum pump
> >during your polish so that the wafer is not picked up.
> >
> >Thanks,
> >SangBum
> >
> >----- Original Message -----
> >From: "Chong Xie" < chongxie at stanford.edu >
> >To: cmp at snf.stanford.edu
> >Sent: Friday, April 10, 2009 10:58:58 AM GMT -08:00 US/Canada Pacific
> >Subject: Wafer broken
> >
> >Dear CMP users,
> >
> >The CMP broke most of my wafers (3 out of 4) last time I use it.
> >Chucking was all right, but the wafers were broken during polishing.
> >I was just using the normal setting:
> >
> >Platen: 50RPM
> >Head1: 30RPM
> >Head2: 60RPM
> >
> >Polishing pressure: 200gm/cm2
> >Retainer pressure: 300gm/cm2
> >
> >My wafers have 2 um deep trenches on them. I thought that might be
> >the reason, but the same conditions worked for me all right before.
> >I was wondering whether I could tune any of these parameters. Dose
> >anyone have similar problems before?
> >Any input is appreciated, and thanks in advance.
> >
> >
> >chong
> >
> >
> >
> >--
> >Christopher McGuinness
> >SLAC - Advanced Accelerator Research Department
> >Stanford University - Applied Physics Department
> >www.christophermcguinness.com





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