Sputtering of Cr film

Hi, I am having issues with magnetron sputtering of Cr. The chamber and the film seems to have coloration after depositing the film at 3 mTorr
and a DC power of 50-100 W. Since the Cr film should look like a nomal metal (no color), I am looking to find solution to this issue. Also, can anybody help me in understanding the drift in the manometer pressure reading when the plasma is turned on for deposition? I would appreciate any input. thanks.
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I would check the purity of your sputtering gas as well as the base pressure. If you have access to an RGA, use that prior to sputtering and just after.
Kitty
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The base pressure is ~ 0.5 microTorr. I need to check the purity of the gas. However, this coloration occurs only when I try and deposit at high temperature ( 650 oC). Thanks.
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snipped-for-privacy@googlemail.com wrote:

What purge gas are you using before pulling a vacuum?
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Thanks for your reply. I ramp the temperature down to 50 oC before venting the vacuum with nitrogen.
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wrote:

What gas are you using for the actual plasma? Nitrogen in the sputtering chamber will cause a reactive sputtered film. I assume you are using Ar as the sputtering gas? I personally would not vent a sputtering chamber with N, if you must vent it, why not use Ar ? Do you vent the chamber because you do not have any type of "prechamber" like a Loadlock? At what mTorr are you sputtering? When sputtering Cr, Al etc, I like to have the presput pressure at least 10-7 x 6 or lower. Also, what is the substrate material and what has been the preclean process prior to sputtering the film?
Kitty
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I am using Ar for sputtering. The sputtering pressure is between 3-5 mTorr. Yes, I dont have have loadlock, hence, I the need for venting the chamber. I have used Si and MgO as substrates. The cleaning process involved Sonication in Acetone, immediately followed by rinsing in Iso propanol and DI water (DI water only in the case of Si). After which they were immediately dried under the burst of ultra high pure Nitrogen. The base pressure is in mid 10-7 Torr. I shall try and vent the system in Ar next time around. Thanks. sudhee
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wrote:

Hmm, well I am thinking that all substrates must have significant rinse in DI water, otherwise residue you cant even see, will adversely affect the film purity. If you have sputter etch capability that would be helpful for a preclean of the substrates or baking at high temp for a few hours {500-800C] Also, are you sure the deposit temperature is 650C ? This is extremely high for sputtering parameters. It might help to get the sputtering temp into the 200-300C range also. I have had to work with systems without the Loadlock advantage { and with !} and found that I had to purge the sputtering chamber multiple times with pumpdowns in-between........just a thought. Try purging with Ar 3x and then pumpdown 3x.....just my 2 cents.......... Keep us posted on your development & progress!
Kitty
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Thanks a lot; Will post the developments.
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