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Problem of Tantalum

Dear Sir,

I am having a problem of Tantalum etching. We have got the Ta film by sputtering method. The thickness of the film is of about 400 nm. The Tatanlum membrane, after etching, will be oxidized and acts as the Ion Selective Membrane of the Ion Sensitive Field Effect Transistor (ISFET). We use the etching solution of HNO3(65%): HF(48%): H2O (1:1:4 in Volume).

The etching process is very difficult to occur, and we are not sure what is the reason so I am writing this letter to ask you if you could give me any suggestion to solve that.

I hope to hear you very soon.

Sincerely yours,

Mai Anh Tuan
Hanoi University of Technology - Hanoi, Vietnam
 

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Hello,

Here's another recipe:

Water: 620 parts
Hydrofluoric acid :180 parts
Chromium trioxide :200 parts
Dodecylbenzene sulfonic acid : 0.1 part

Be careful with this mixture.

(There are many issues concerning the safe use of these materials, see the Material Safety Data Sheets for these products, and consult with experienced chemical workers about handling, use, ventilation, storage, and disposal - editorial note)

Good luck,

Sjamp van Esch
- Eindhoven, The Netherlands