[labnetwork] Crucible liner for platinum

[Shivakumar Bhaskaran]

Matt,

First of all your crucible liner should touch all the surface of the hearth else you might not have uniform temperature on your material/crucible and due this the hearth might crack. If you know the make or model of the Hearth any vendor can tell you what size of the crucible part need to be ordered. Graphite liner is the one you need. Do not fill the liner full with material. For Platinum fill atelast 25% volume, in my experience if you fill more than 50% volume then there is a chance of Pt coming out of your crucible and might get in contact with hearth and then this will crack your crucible. We add only less amount of Pt and replenish as needed. I use graphite crucible from lesker, ours is 15cc, there are two types on with thick and thin wall I use thick wall graphite crucible liner. But for 7cc getting a thick wall might be an issue. Yes Pt sticks to our liner all the time but my liner don't crack and I set up the recipe as slow ramp until we get desired rate and soak atleast 1min before you start evaporating.

Hope this helps

-Best
-Shiva


Shivakumar Bhaskaran, Ph.D.
Searle CleanRoom Manager
The University of Chicago
5735 S.Ellis, Room 032
Chicago-60637
Ph:773-795-2297
https://searle-cleanroom.uchicago.edu/

From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Matt Dwyer
Sent: Wednesday, September 16, 2015 1:25 PM
To: labnetwork at mtl.mit.edu
Subject: [labnetwork] Crucible liner for platinum

Hi all,

I have a 7cc vitreous carbon crucible liner with platinum melt that has cracked along the walls and base. I want to send this off for reclaim and put together a new platinum melt but would like advice on what crucible liner to use. The crucible will be used in two ebeam evap tools, but in one tool only the crucible base touches the hearth (i.e. not the sides). The platinum has bonded with the VC crucible and thus cannot be transferred to a new crucible (I presume I can't just crack the crucible off from the platinum and put it in a new crucible?).

My crucible material options are graphite, Fabmate, vitreous carbon, and tungsten. Neyco<http://www.neyco.fr/pdf/Materials_H_Liners.pdf> recommend graphite or tungsten. VEM<http://www.vem-co.com/sites/default/files/pdfs/VEM_Thin_Film_Evaporation_Guide.pdf> recommend CG (graphite?) or ThO2. Plasmaterials<http://www.plasmaterials.com/ThinFilmEvapMatSrcRef.pdf> recommend graphite or ThO2. Kurt Lesker recommend graphite or Fabmate (not explicitly recommended).

It seems that no one recommends vitreous carbon so perhaps that was the wrong material to use for platinum. I suspect tungsten may alloy with platinum so this may be a poor recommendation by Neyco.  As the reclaim value covers only ~50% of the cost of new material, I would like to avoid cracking this crucible for as many depositions as possible.

Suppliers I am considering are Kurt Lesker (graphite, Fabmate) and Sage (graphite, vitreous carbon).

Any advice would be greatly appreciated.

Thanks in advance,
Matt Dwyer
Grad student, UW-Madison
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