Sputtering of Cr film

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

What purge gas are you using before pulling a vacuum?

Thanks for your reply. I ramp the temperature down to 50 oC before venting the vacuum with nitrogen.

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.

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

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

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{Ar} 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

Thanks a lot; Will post the developments.