[labnetwork] Copper Through-Glass Vias on fused silica

[Eric Deguns]

Hi Larry,

I'll reach out to you from my Veeco email.  Long story short is that we
have established processes for PE-ALD of Cu, other thermal processes for Ru
/ Pt to use as seed layers prior to Cu electroplating.

We also typically do a SiO2 / TiN deposition prior to this to act as an
adhesion and barrier layer.

Lot of experience with this - shouldn't be an issue.

Best,

Eric




On Wed, Feb 26, 2025 at 5:06 PM Hathaway, Malcolm R <
hathaway at cns.fas.harvard.edu> 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> on behalf of Hess,
> Larry A. (GSFC-5530) <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>
> *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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