[labnetwork] Black Silicon

[N P Vamsi Krishna]

Hi Tom,

Thank you for this question. I had a similar problem with Cryo etch in the
Oxford tool. I didn't understand why this is happening, but I was able to
make some repeatable samples.



My Cryo etch process was on dies and not on the full wafer. I bond the die
to the carrier wafer. Here are my observations:

1.     Pre-conditioning of the chamber with the cryo process helped a lot.

a.     After the condition run, if I see the black silicon, chamber
cleaning is required.

b.     Ar + Oxygen clean and then oxygen clean helped.

c.     Followed by repeating the conditioning.

2. Etching fewer dies worked better than multiple dies on the wafer.

3. After some successful runs, I generally observe black silicon starting
on one of the corners of the carrier wafer. Once I see the black silicon,
it's better to discard the carrier wafer and use a fresh one. Using the
same wafer resulted in full black silicon affecting the die and chamber
needing cleaning and condition again.

4. Also, the results were bad if the temperature was unstable.



To the best of my knowledge, chamber conditioning is the key.



Once your issue is fixed, I request you to share the knowledge and
experience.

Thanks & br,
Vamsi


On Fri, Apr 9, 2021 at 4:16 PM Ferraguto, Thomas S <Thomas_Ferraguto at uml.edu>
wrote:

> Colleagues,
>
>
>
> I’ve been doing some deeper than usual silicon etch on my Oxford ICP 380
> in Cryo mode using and SiO2 mask (SF6 & O2)
>
>
>
> I’ve been getting what I believe to be a “Black silicon” artifact, and
> would either like to NOT get it or remove it.
>
>
>
> If anyone has thoughts or could point me in the right direction , I’d
> appreciate it.
>
>
>
> Best Regards
>
>
>
> Tom
>
>
>
>
>
> Thomas S. Ferraguto
>
> Saab ETIC Nanofabrication Laboratory Director
>
> Saab ETIC Building Director
>
> 1 University Avenue
>
> Lowell MA 01854
>
> Mobile 617-755-0910
>
> Land 978-934-1809
>
> Fax 978-934-1014
>
>
>
>
>
>
>
>
>
>
>
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-- 

___________________________________________________

N.P.  Vamsi Krishna, PhD

*Staff Scientist*

Pritzker School of Molecular Engineering, *The University of Chicago *

*Resident **Associate*

Center for Nanoscale Materials, *Argonne National Laboratory *

Phone: 1 (331) 757-8565
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