STS shower head thru etch effect

[Jim McVittie]

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 invensense.com wrote:

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