[labnetwork] Sputtering issue

Mon Apr 17 09:59:14 EDT 2023

Hi Saba, 

The strike pressure (2e-3 mbar which is about 1.5 mTorr) sounds too low for me. Usually from my sputter system, the strike pressure would be 20~30 mTorr, then we would adjust it below 5 mTorr for deposition. 
If the pressure is low, sometime there will be some difficulties to start the plasma. It might be the reason it cannot support the stable plasma status especially for brand new targets. 

If your system can show you the current, voltage for the sputter gun including ‘50W’, you may be able to get more information once the plasma is struggling. 
The flakes on the target could be generated by too much arching during the sputtering process. You could test a different easy target like Al on the same gun to see what is the performance. 

I also agree with Michael about the magnets. What does the magnet look like, a ring magnet? If you have a Gauss meter, you can check the magnets’ condition. If not, check it as Micheal suggested. If the sputtered mark on the target is not a regular ring, you’d better check the magnets underneath. 

Best,
Jing
---------------------------------------
Jing Guo Ph.D.
Research Scientist
SEA Cleanroom (SST 017)
Rice University
Houston, TX 
jeanne.guo at rice.edu
713-348-8227

> On Apr 15, 2023, at 1:55 PM, Michael Yakimov <yakimom at sunypoly.edu> wrote:
> 
> I would check magnets' condition. Once upon a time, I had a ring magnet on a similar one to partially lose magnetization. The result was the strange shape of plasma and a few other funny things. Once removed, it was fairly obvious that the screwdriver sticks to some areas better than others. 
> 
> _______________________________________________
> Michael Yakimov
> Research scientist
> College of Nanoscale Science and Engineering
> SUNY Polytechnic Institute
>  
> 253 Fuller rd.
> Albany NY 12203
>  
> Phone: 518-437-8609 lab
> e-mail: yakimom at sunypoly.edu <mailto:yakimom at sunypoly.edu>
> 
> 
> 
> From: labnetwork <labnetwork-bounces at mtl.mit.edu <mailto:labnetwork-bounces at mtl.mit.edu>> on behalf of Saba Sadeghi <saba.sadeghi at uwaterloo.ca <mailto:saba.sadeghi at uwaterloo.ca>>
> Sent: Friday, April 14, 2023 4:15 PM
> To: Jing Guo <jeanne.guo at rice.edu <mailto:jeanne.guo at rice.edu>>
> Cc: labnetwork at mtl.mit.edu <mailto:labnetwork at mtl.mit.edu> <labnetwork at mtl.mit.edu <mailto:labnetwork at mtl.mit.edu>>
> Subject: Re: [labnetwork] Sputtering issue
>  
> Hi Jing, 
>  
> Thanks a lot for getting back to me and the helpful discussion. 
>  
> This was a pure Ta sputtering. I could ignite the plasma at 50 W, 30 sccm Ar, 2E-3 mbar pressure but then the glow spots appear after a few minutes which led to the plasma extinguishing! I could reignite the plasma again by ramping down the power and then up to 50W! by the two hours of sputtering, I meant the sputtering collectively lasted two hours until it shorted.  
>  
> The sputtering gun housing were clean before the sputtering, but after it looks like particles accumulated on the surface of the target! and eventually ended up in the housing and caused the short (picture attached) 
>  
>  
> Thank you. 
>  
> Best, 
> Saba 
> 
> 
> From: Jing Guo <jeanne.guo at rice.edu <mailto:jeanne.guo at rice.edu>>
> Sent: April 14, 2023 10:25 AM
> To: Saba Sadeghi <saba.sadeghi at uwaterloo.ca <mailto:saba.sadeghi at uwaterloo.ca>>
> Cc: labnetwork at mtl.mit.edu <mailto:labnetwork at mtl.mit.edu> <labnetwork at mtl.mit.edu <mailto:labnetwork at mtl.mit.edu>>
> Subject: Re: [labnetwork] Sputtering issue
>  
> Hi Saba, 
> 
> Was the process a pure Ta sputtering or reactive sputtering? For a pure Ta DC power sputtering process, usually it shouldn’t generate that much particles. Ta coating on the sputter gun house/chimney should have a good adhesion. Any accumulated particles on the Ta target surface after ~ 2 hours sputtering?
> 
> If the chimney or clamp ring for the target has been coated too much materials, you need to clean the whole kit and measure the gun to the ground layer by layer once you install a target. Another issue could be that some magnets got demagnetized which cannot provide strong magnetic field on the target surface. 
> 
> What was the strike condition, like pressure, power, gun voltage/current? Did you see whether the voltage/current can stabilize once the plasma was generated?
> 
> There are several ways to figure out it is the sputter gun issue or a Ta target issue. Normally targets should be fine. 
> 
> Thanks.
> 
> 
> 
> Best,
> Jing
> ---------------------------------------
> Jing Guo Ph.D.
> Research Scientist
> SEA Cleanroom (SST 017)
> Rice University
> Houston, TX 
> jeanne.guo at rice.edu <mailto:jeanne.guo at rice.edu>
> 713-348-8227
> 
> 
> 
> 
> 
> 
> 
>> On Apr 13, 2023, at 6:55 PM, Saba Sadeghi <saba.sadeghi at uwaterloo.ca <mailto:saba.sadeghi at uwaterloo.ca>> wrote:
>> 
>> Dear Labnetwork community, 
>>  
>> I am having an issue with magnetron-sputtering of tantalum with DC power. After a few minutes of sputtering Ta glow spots appear on the surface of the target that eventually cause the plasma to distinguish.  I have loaded two fresh 0.31”-thick Ta targets, but both times the same problem occurred, and both times it generated enough particles in a short amount of time ( about 2 hours of sputtering, accumulatively) that led to shorting of the source. 
>>  
>> I suspected that this might be a cooling issue, but there is enough flow rate at the sputtering source,and I use indium thin foil for thermal contact between the cathode and the target (recommended by the company- MeiVac). 
>> 
>> Have you experienced such a problem? I am wondering if this could be an issue with the sputtering source or could somehow the two Ta targets I loaded have been compromised?  
>>  
>> Thank you very much. 
>>  
>> Best regards, 
>> Saba Sadeghi 
>> IQC, University of Waterloo 
>>  
>> 
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