[labnetwork] Copper Through-Glass Vias on fused silica
Christopher Alpha
alpha at cnf.cornell.edu
Thu Feb 27 16:17:26 EST 2025
We use pulsed power supplies with forward and reverse current
capabilities, so you can tune the grain size and growth better than with
straight power...it takes some development time for sure to get it
right. (electrochemistry is black magic!) Plating off of Pt is usually
pretty good assuming you have a nice contiguous film that you can
solidly contact in your fixturing. I'd also advise to try and go slowly
and not try for a plating speed record...
On 2/27/25 16:07, Artner, Diane M wrote:
>
> For the electroplating of vias with Pt seed, have you seen poor
> nucleation, basically large grain growth vs uniform small grain size
> bottom up fill?
>
> *From:*labnetwork <labnetwork-bounces at mtl.mit.edu> *On Behalf Of
> *Christopher Alpha
> *Sent:* Thursday, February 27, 2025 10:41 AM
> *To:* labnetwork at mtl.mit.edu
> *Subject:* Re: [labnetwork] Copper Through-Glass Vias on fused silica
>
>
>
>
> This message was sent from outside of HRL. Please do not click links
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>
> Hi Folks,
>
> (RE: Mac's comments)
>
> We often do Pt seed layers by ALD for via Cu electroplating
> fills...you can get voids though depending on aspect ratio and how you
> drive the plating. If a a hollow wire is OK this is fine to do in
> this fashion.
>
> If you want a full solid fill we have done Au or Pt sputter on only
> one side of a very high aspect ratio via and basically try to sputter
> the hole mostly if not fully closed and use a plating fixture that
> makes contact on the back side with the Pt seed, leaving the other
> side exposed in the plating bath, then you can get a nice fill by
> plating from the bottom of the via up. Overtop the via/wafer's
> surface, and CMP everything clean and flat (remove seed either
> selectively with wet chemistry if possible or CMP that off too).
>
> Your mileage may vary...electroplating is a dark art.
>
> Best,
>
> C
>
> --
> Christopher Alpha
> User Program Manager
> Cornell Nanoscale Facility
> Cornell University
> 250 Duffield Hall
> 343 Campus Rd
> Ithaca, NY 14853
> tel (607)254-4913
> Any email from me will always really be from me without any AI "assistance"
>
> On 2/26/25 13:04, Hathaway, Malcolm R wrote:
>
> Hi Larry,
>
> As it happens, Cu is not an established ALD process yet (that I am
> aware of).
>
> Pt is common, but for your purposes (filling a 20um diameter hole)
> Pt would likely too expensive. In fact, ALD is probably not a
> viable option because you will need a layer slightly thicker than
> the radius of the hole (i.e. 10 um) and ALD of almost anything in
> a 10um thickness will take 2-3 weeks (at least in our systems).
> We tend to speak of dep thickness/cycle (~1A) because to speak of
> rate in thickness/min is too embarrassing!
>
> Which is to say, ALD is slow.
>
> Typical films are under 200nm.
>
> Material-wise, Pt, Ru, and some other conductors are available,
> but they tend to be on the (even) slower side. Some newer systems
> will get cycle times down to achieve 20-30 cy/min, but still
> nothing approaching CVD growth rates.
>
> A Pt liner (or other conductive material) with Cu electroplating
> is much closer to a standard process for this sort of thing. And
> if you wanted to get fancy you could even consider selective W
> CVD, but that would require a bit of process development.
>
> I'm happy to chat about this off-line if you like. Hopefully
> others with proper electroplating experience will chime in shortly.
>
> Mac
>
> Harvard CNS
>
> ------------------------------------------------------------------------
>
> *From:* labnetwork <labnetwork-bounces at mtl.mit.edu>
> <mailto:labnetwork-bounces at mtl.mit.edu> on behalf of Hess, Larry
> A. (GSFC-5530) <larry.hess-1 at nasa.gov> <mailto:larry.hess-1 at nasa.gov>
> *Sent:* Wednesday, February 26, 2025 9:36 AM
> *To:* labnetwork at mtl.mit.edu <labnetwork at mtl.mit.edu>
> <mailto:labnetwork at mtl.mit.edu>
> *Subject:* [labnetwork] Copper Through-Glass Vias on fused silica
>
> Hi,
>
> I am looking for a (hopefully established) source to deposit ALD
> copper on Though-Glass Vias.
>
> The vias are about 20um in diameter with an aspect ratio of about
> 10:1.
>
> I would also consider Cu electroplating( after an appropriate ALD
> adhesion/base layer), but I’m not sure how feasible that is given
> the via diameter and aspect ratio.
>
> Thanks for your help!
>
> Larry
>
> Larry A. Hess, PhD
>
> NASA
>
> Goddard Space Flight Center
>
> 8800 Greenbelt Road
>
> Code 553, Detector Systems Branch
>
> Building 11, Room E011
>
> Greenbelt, MD 20771
>
> 301-286-0259 (P)
>
> 301-286-1672 (F)
>
>
>
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--
Christopher Alpha
User Program Manager
Cornell Nanoscale Facility
Cornell University
250 Duffield Hall
343 Campus Rd
Ithaca, NY 14853
tel (607)254-4913
Any email from me will always really be from me without any AI "assistance"
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