STS shower head thru etch effect

Chris Kenney kenney at slac.stanford.edu
Tue Jul 5 10:54:31 PDT 2005


Sorry to over load all the STS users' mailboxes, but I've
attached an image of the tilt we observed. To set the scale
this is a 525 micron thick wafer and this image was
taken near the wafer's edge. As you can see the tilt angle
varied strongly with distance from the edge.

On Tue, 5 Jul 2005, Chris Kenney wrote:

> 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.
>
> Chris
>
> 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 invensense.com wrote:
> >
> > >    Part 1.1    Type: Plain Text (text/plain)
> > >            Encoding: 8bit
> >
> >
>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: tiltvariation.jpg
Type: application/octet-stream
Size: 22862 bytes
Desc: 
URL: <http://snf.stanford.edu/pipermail/stsetch/attachments/20050705/fd07d36a/attachment.obj>


More information about the stsetch mailing list