Hi Christoph

There are a couple of ways.
If the wafers have an etch back, you can take a small  Laser pointer or
even a high intensity LED ( I use a simple writing pen with one I got )
and shine it on the back to see what the pattern is.  If the backside is
too highly reflective this wont work though.
Another way to do this with a laser  is to put a white disk witha hole
to let the laser light though against the laser and hold the wafer in
front of it and look at the reflected pattern back on the front of the
white disk.
for 1-0-0 you would see a four line projection of each quadrants ( you
maybe see secondary segments also )
For 1-1-1 you would see ( Best Case) a 3 line projection or any multiple
of three in equal proportions.


A third way- but destructive would be to break the wafer- applying a
sharp accute pressure at the centerpoint of the wafer will cause it
break on the break planes.
a 1-0-0 will normally break into 4 sections at approx- 90degree each.
A 1-1-1 will normally break in either 3 or 6 sections.

Try these out and see what you get.  This is good information and not
all that well known on the device side but we use it all the time on the
base material side of the biz.

Regards
Ken Smith
Kmbh Technologies  ( aka Associates)

Christoph Wild wrote:

> I have ordered a batch of silicon wafers without flat.
> We ordered 100 oriented wafers, however, now it turns out that some of
> the wafes are 111 oriented.
> Is there a quick test which allows us to discriminate between 100 and
> 111 oriented wafers ?