STS shower head thru etch effect

Chris Kenney kenney at
Tue Jul 5 10:43:02 PDT 2005

We also observed a shower-head effect several years ago on STS1
and we thought it might be associated with use of the aluminum holder.

Although we don't generally look for them, we haven't noticed tilted
features before or since.

Thanks for providing the references.


On Tue, 5 Jul 2005, Jim McVittie wrote:

> Jaime,
> It sounds like you are seeing a charging effect. Back in the early 90's,
> I did a bit of work on etch profile distortion due charging. We did
> etching experiments, direct charging measurements and simulations. See
> papers below. The work was done on one of the Dryteks for trenches
> etched in the range of 5 to 10 deep. In general, charging is due to
> plasma non-uniformity although the pattern on your wafer can have a
> strong effect. In the Drytek case we used a  magnet  to cause plasma
> non-uniformity. You are the first user to ever report this effect on
> STS-1 so I suspect a temporary hardware problem could be the cause.  Can
> you give me more details on what you are seeing, such as how the tilt
> varies across the wafer. Also are you seeing a lot of etch rate
> non-uniformity.
>     Jim
> S. Murakawa and J.P. McVittie,  "Ion Trajectory Distortion and Profile
> Tilt by Surface Charging in Plasma Etching", Appl. Phys. Letts., vol.
> 64(12), pp.1558-1560, Mar., 1994.
> S. Murakawa and J.P. McVittie, "Direct Measurement Of Surface Charging
> Potential In Plasma Etching", Proceedings 2nd  Intnl. Conf. Reactive
> Plasmas, pp. 747-750, Jan. 1994, Yokohama, Japan, also in Jpn. J. Appl.
> Phys., Vol. 33, pp. 4446-4449, Part 1, July 1994.
> S. Murakawa and J.P. McVittie, "Mechanism of Surface Charging Effects on
> Etching Profile Defects", Proceedings of Symp. on Dry Process ( IEE
> Japan), pp. 39-44, Nov. 1993, Tokyo, Japan, also  in Jpn. J. Appl.
> Phys., Vol.33, pp.2184-2188, 1994.
> jgarate at wrote:
> >    Part 1.1    Type: Plain Text (text/plain)
> >            Encoding: 8bit

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