[labnetwork] Co sputtering targets question

[Laszlo Pethö]

Dear Jing,



The surface of the targets can look vastly different depending on the
process conditions they have been used with.



Some parameters that will influence this:

   -

   The power that goes into the target during sputtering – plasma power
   minus backside cooling
   -

   Plasma density: the type of magnets used in the magnetron, and the power
   source type (DC/RF/HiPIMS)
   -

   If reactive sputtering was used; including a chamber or argon line leak

You can often observe target recrystallization and grain growth if the
plasma power is too high.



There must be already stronger than standard magnets in the magnetron,
since cobalt is ferromagnetic. The cross-sections of the racetrack patterns
show that you have different strength magnets as well – eg. the bottom left
target shows a sharp V-shape. This magnet was about double as strong as the
one used with the target on the top left.



The matte surface can result either from low plasma powers or from a
compound formed on the target during sputtering. In my experience this
looks like the latter, probably from a leak in the argon line. See the dark
grey central disc on the target in the top row, center. This should be
porous cobalt oxide, might be useful to check with EDX or XRF.



The supplier is not relevant in this aspect; these surfaces can be obtained
with targets from any source.



I would recommend the following:

   -

   Run a leak check on the argon line with a RGA
   -

   Use a getter metal (Zr, Ti, Al) and check the oxygen content of
   deposited films
   -

   Decrease power if you see large, mm-sized grains
   -

   Check if backside water cooling is sufficient



I hope this helps!



All the best,

Laszlo





Laszlo Pethö

Scientist

Empa

Swiss Federal Laboratories for Materials Science and Technology

Feuerwerkerstrasse 39

3602 Thun

Switzerland

Tel +41 58 765 63 45

Fax +41 58 765 69 90

laszlo.petho at empa.ch

www.empa.ch



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On Mon, Jan 8, 2018 at 5:15 PM, Guo, Jing <jguo5 at central.uh.edu> wrote:

> Dear Colleagues,
>
> Happy new year!
>
> I found a lot of used Co targets while I was checking all the sputtering
> targets. They are all Co targets from two orders which showed different
> property as shown in the attachment.
>
> For the top row, all of them surface is shinning but the sputtered ring is
> not perfect round shape and sharp.
> For the second row, the surface is quite different from the top row. And
> the sputtering mark/ring is sharp and round.
>
> The second picture is Ag (99.99%) targets from different company. The
> surface showed different property after sputtering also.
>
> I guess the difference came from the different fabrication process to make
> the targets. Is there anyone familiar about the targets fabrication
> process? Will this difference affect the sputtering property?
> Could you please advise which type of the targets should be ordered next
> time?
>
> Thank you.
>
>
>
> Best Regards,
>
> Jing
>
> Research Lab Supervisor
> Nanofabrication Facility
> University of Houston
> Postal Address:
> UNIVERSITY OF HOUSTON
> NANOFABRICATION FACILITY
> 3517 CULLEN BLVD, RM 1011
> HOUSTON TX  77204-5062
> Phone:  832-842-8822 <(832)%20842-8822>
> Email:  jguo5 at central.uh.edu
> Web:  www.uh.edu/nanofab
>
>
> _______________________________________________
> labnetwork mailing list
> labnetwork at mtl.mit.edu
> https://mtl.mit.edu/mailman/listinfo.cgi/labnetwork
>
>
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