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topic 17871

Etching solution for Tantalum/Tantalum Nitride


Q. I am trying to find an etch that will etch tantalum and/or tantalum nitride with some selectivity to copper. I've tried various mixtures of HF and H202, but they all rapidly attack the Cu. Does anyone know of any additional wet etches for tantalum or more specifically tantalum nitride?

David Arnold
Georgia Tech - Atlanta, Georgia


A. Try H202 and EDTA. This will strip titanium nitride and since tantalum is also a refractory group metal I think it would also work.

Jon Quirt
- Fridley, Minnesota


! I tried EDTA and H202, and it works quite well. I mixed 1:1 0.5M EDTA and 30% CMOS grade H202. It took 1 hr. to etch ~2000A Ta at 60° C. The Cu structures bubbled some (not sure of the etch rate), but remained intact.


David Arnold
Georgia Tech - Atlanta, Georgia, USA


Q. I tried out the 1:1 proportion of 0.5M EDTA and H2O2 (but I'm using 35%), but my Ta film of 300A is still intact. Anyone know why? Please enlighten me.

Edmund Lim
- Singapore


A. Was the etchant at elevated temperature? I use 1M EDTA:H202 1:1 at 60° C and get an etch rate of ~1000-2000A/hr. Be patient.

David Arnold
Georgia Tech - Atlanta, Georgia, USA


Q. I bought a bottle of EDTA (Ethylenediamine Tetraacetic Acid). It is not dissolve in what. Then how do you make the 0.5M EDTA?

Jun Lu
semiconductors - Ottawa, Ontario, Canada

June 6, 2012 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. We have been asked to etch a .003" tantalum component. Initial research recommends a 1:1 HF/Nitric acid bath. We have been unsuccessful to date (resist gave prior to achieving depth). Any recommendations on formula or process?

Ace Sawqnack
- Buffalo, New York, USA

June 7, 2012

A. Hi Ace.

As you see, we appended your inquiry to an earlier thread about etching tantalum. You might also look at letters 5648 and 22882, or try the Google custom search engine. Good luck.


Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha

July 13, 2012

A. What is the purpose of tantalum etching? If not grain revealing, then you will probably prefer tantalum electropolishing in less hazardous electrolytes. The surface will be smooth and bright.

Anna Berkovich
Russamer Lab
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Pittsburgh, Pennsylvania 
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