12/16/96
I have a general question that may be obvious to some, but is
not obvious to me. When is a sputter coater target "spent",
and require replacement? Does it simply no longer coat the
sample effectively, or is it something more subtle? In the case of a
blended target (mine is 60:40 Au/Pd), does one element deplete before
the other? I have had the same target for several years now.
TIA,
Bob Citron
Chiron Vision
555 W. Arrow Hwy
Claremont, CA 91711
USA
Ph: (909)399-1311
Email: Bob_Citron@cc.chiron.com
it's spent when you sputter a hole in it. Take it out of the holder and hold
it up to the light- if you can see little pinholes, it's time. If you leave
it too long, you'll start sputtering the face of the cathode.
If the target is bonded, you'll start to sputter the substrate when it burns
through, this may be harder to detect by visually examining the target. I
have no experience w/ bonded targets.
As for a blended target, the ratio shouldn't change as it is used.
Best.
Pat
Cubdrvr@aol.com
It is my understanding that gold and palladium sputter congruently
unlike evaporation where the two metals are deposited as a function of
their melting point. You could check this by depositing some Au-Pd and
checking the ratio br XRMA. We consider a target is worn out when holes
begin to appear. We don't seem to get much joy in re-cycling target
material.
Seasons greetings from Cambridge UK
Patrick Echlin
Multi-Imaging Centre
Scool of Biological Sciences.
pe13@cus.cam.ac.uk
Let me start by introducing myself, I am the Business manager for the
POLARON range of preparation equipment including coaters. Your
question to the target dilemma is simple, but interesting one.
The most simple answer is that when the target becomes perforated
then it is deemed to be spent. BUT, depending on the backing metal it
is possible to continue sputtering with this same target for some
time.
What happens is that the target area that is being bombarded is
reduced so the sputter rate is continually in decline, if the coater
has a sufficiently strong Plasma then the backing metal will be
sputtered at a slower rate but will contaminate the gold or target
material. Not a problem for visualisation of the surface by SE
detector.
When the target is of a mixed metal composition then the softer (Less
dense) material will erode quicker, in practice this is not
significant as the mixed metal is used to stop conglomeration and
island formation of the sputtered material (normally gold) hence
offering higher resolution or more correctly, smaller grain size.
Our recommendation for reproducible high quality work is to change
the target once perforated.
There is much more that we could discuss but I hope this answers your
question.
Best regards - Tony
Regards,
Tony King
Product specialist
VG Microtech/ Polaron range
Tel: +44 (0)1825 746251
Fax: +44 (0)1825 768343
E&OE
Energy Beam Sciences, Inc.
Adding Brilliance To Your Vision
ebs@ebsciences.com
http://www.ebsciences.com/
curious regarding those people who get an incredible 5yrs + out of
their targets. Now granted there are differing rates of usage, and
differing deposition amounts in various labs and users, but it would
seem that target thickness is one of the major factors in this
longevity.
I have a Denton Desk II, which takes a disk target (2.375"
diameter). Looking through the catalogs and talking with a few
other EM labs, targets vary from 0.0015" to 0.01" thick. Since we
are generally talking about Au or Au/Pd electrical conductivity/
resistance through the target shouldn't be a major concern (?). Is
there any procedures, other than trial and error, for determining
how thick a target one can use? Or even more specifically can anyone
give me the answer for a Denton Desk II ?
Note: It is not my intent to support nor condem in any way any
sputter coater vendor.
Richard E. Edelmann, Ph.D.
Electron Microscopy Facility Supervisor
352 Pearson Hall
Miami University, Oxford, OH 45056
Ph: 513-529-5712 Fax: 513-529-4243
E-mail: edelmare@muohio.edu
willing to give us some credit on our old target.
Refining Systems, Inc.
P.O. Box 72466
Las Vegas, NV 89170
702 368-0579
702 368-0933 FAX
Henk Colijn colijn.1@osu.edu OSU Campus Electron Optics Facility
"converted" back into "money" has to be analyzed by the refiner and the
minimum analysis and refining cost is typically more than the value of gold
in one ounce (or nearly so). So unless you have a dozen sputter coaters
running side by side, all day long, a typical user would be unlikely to ever
generate enough precious metals scrap to make it economic to send back to
the refiner.
That is why we have offered a "trade in" program, send us back your spent
cathodes and we will grant a 10% discount on a new one. When we have
accumulated 20-30 troy ounces of spent cathodes (of a given metal), we then
return them for refining and realize the economic value. This makes a lot
of sense from a non-renewable resource standpoint as well, since once the
world's supply of gold is gone, it is gone.
Note of caution: As with any commodity being set aside for recycling, do
not mix cathodes of different compostions. Keep them separate! They have
greater economic value separated than if they are mixed together and without
traceability as to metal composition.
Chuck
Charles A. Garber, Ph. D. e-mail: cgarber@2spi.
com
PRESIDENT
SPI SUPPLIES/STRUCTURE PROBE, INC.
WEST CHESTER, PA 19381-0656 USA
http://www.2spi.com
We get our material from Argen Precious metals in Edenvale
Johannesburg South Africa. (most currency is strong to the rand and may be of a advatage)
They make up to order and may even cut and fit the target material to the target
base (this is by hear say). The advantage is that they keep the waste
and you may get a refund or you may not even have to pay for it!(if it
is true!) They made to spec when ordered. To my knowledge 60% Pd 40% Au is preferable, suppose
to produce a finer coating. . Tell: +27 11 609 8640
Fax: +27 11 452 3918
Standard disclaimer.
Best of luck. And seasons greetings
Stephan H Coeztee
Electron Microscope Unit
Private Bag 3
Wits
2050
South Africa
Stephan@Gecko.biol.WITS.ac.za
Tell: +27 11 716 2419
Fax : +27 11 339 3407
Gold is soft and easily worked. In Australia we have many local jewellers
who can refashion gold into usable sputter targets. Try your local yellow
pages. Gold plated onto a baser metal is a different matter.
Mel Dickson
M.Dickson@unsw.edu.au
apertures or want to recycle the silver in their dark rooms - unless you
are in a situation where you can operate on an appropriately large scale,
the time and effort simply doesn't justify the return.
Regards,
Larry Stoter
LPS@teknesis.demon.co.uk