[labnetwork] Sputter problem

[Steven Foland]

Hi Su,

I am sputtering reactively. Power is 300W during cleaning, 200W during coat.
Pressure is 40 mTorr during clean, 4 mTorr during coat. Flow rates are: 20
sccm Ar, with 1.65 sccm O2 during coat.

Thanks,
Steven

On Fri, Jun 24, 2011 at 11:37 AM, Gupta, Su <sgupta at eng.ua.edu> wrote:

> Hi Steven:
>
> Are you sputtering reactively or from a TiO2 target? Please give me power,
> pressure, flow conditions for your coating and cleaning cycles. That will
> help me to understand your problem better.
>
> Thanks, Su
>
> ________________________________
> From: Steven Foland [stevenfoland at gmail.com]
> Sent: Friday, June 24, 2011 10:05 AM
> To: Gupta, Su
> Cc: Keith Bradshaw; labnetwork at mtl.mit.edu
> Subject: Re: [labnetwork] Sputter problem
>
> Hi Prof. Gupta,
>
> We are doing RF sputtering, not DC. Cleaning the target longer does
> increase deposition rate temporarily, but it drops back down quickly. We are
> most likely operating at the "oxidized" rate, but still are unsure why we
> are experiencing this gradual decline in film thickness.
>
> Here is my data from yesterday:
> 1st run: 5 minute clean cycle, 5 minute coat cycle: 250 Angstroms
> 2nd run: 5 min clean, 10 min coat: 198 Angstroms
> 3rd run: 10 min clean, 5 min coat: 118 Angstroms
> 4th run: 5 min clean, 5 min coat: 96 Angstroms
> 5th run: 5 min clean, 5 min coat: 80 Angstroms
> 6th run: 5 min clean, 5 min coat: 90 Angstroms
> 7th run: 20 min clean, 5 min coat: 120 Angstroms
>
> So you see, we have a gradual decline in dep rate, but can increase the dep
> rate slightly by running a longer clean cycle.
>
> If enough time has passed (a day or two) between runs, the rate increases
> back to its original value of ~250 Angstroms in 5 minutes.
>
> Thoughts?
>
> Thank you,
> Steven Foland
>
> On Thu, Jun 23, 2011 at 11:54 PM, Gupta, Su <sgupta at eng.ua.edu<mailto:
> sgupta at eng.ua.edu>> wrote:
> Hi Keith:
>
> Can you give me some more details about your sputter system and the
> processs? For instance, are you sputtering reactively from a Ti target or is
> it TiO2? If you are doing DC reactive sputtering from an elemental target,
> then the target voltage is the best indicator of what is going on with the
> process. For instance, the target may be oxidizing further with each run
> (even with the preclean) and you may be dropping down the slope of the
> hysteresis loop from the 'metallic' rate to the "oxidized" rate, which would
> be accurately reflected in a drop in the target voltage. A small leak or
> outgassing could also cause this type of problem, but it probably would not
> be as regular and systematic as what you are observing.
>
> Regards,
> Su Gupta
> Assoc. Prof, MTE
> Faculty Director, uamcro
> Univ. of Alabama
> ________________________________
> From: labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu>
> [labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu>] On
> Behalf Of Keith Bradshaw [bradshaw1234 at gmail.com<mailto:
> bradshaw1234 at gmail.com>]
> Sent: Thursday, June 23, 2011 5:09 PM
> To: labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>; Steven Foland
> Subject: [labnetwork] Sputter problem
>
> We are sputtering TiO2 .
>
> We begin the day with a 250 angstrom rate....each subsequent run is reduced
> by 10-15% in rate until we are at a 125 angstrom rate.  We are not changing
> anything.
>
> Next day we begin again at 250.
>
> Tried argon clean between runs, tried 3 hour wait between runs, we are
> using a load lock and vacuum looks stable , still rate drops on each run.
>
> Any ideas?
>
> cordially,
>
> Keith Bradshaw
> Dallas
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20110624/6c591c59/attachment.html>