I have tried electropolishing and normal etching using various acidic solutions quoted in literature but it did not work. Please suggest some etchants and electropolishing solutions for me to try.
Dear Dr. Mathew:
Really, sometimes is very difficult found an ideal set of parameters that allow the microstructure (grain-boundary definition or twin) be revealed.
Furthermore, considering that several acid attack were carried out, seems that sample as is exhibits an intrinsic resistance in acid medium.
The effective etching is function of crystallographic plane, someone exhibits easy etching, another planes neither so.
Several kind of etching via acid medium were performed acid medium were conducted. Considering that the alloy cooper is with standing to acid attack, a possible approach is to use procedures applied to revealing of microstructure of materials with similar feature.
It is possible to try for cooper alloy instead acid an alkaline approach to reveal the microstructure. This procedure can be carried out via 20% up to 40% of KOH aqueous or alcoholic.
Some kind of synergetic effect occurs by combining of several electrolytes species, after this is necessary to optimize etching time, tension and current, it is more complicated solution.
Further comparison with parameters previously tried for nanotwinned can be performed with following data: for reveal microstructure of zirconium diboride, a time of etching of 45s can be used. As electrolyte an aqueous solution of HF at 1% is sufficient. Electro-parameters: tension 6V and current below 0.1 A.
Kind regards
Marcos Nobre
Dear Dr. Mathew,
try very simple ones such as H3PO4+alcochol+deionized water under 1.0-1.5 V for 1-2 mins. Next one would be the chemical approach via Fe3Cl+water or addition of aither HNO3 or HCl. This should do the trick. Be careful with HF and KOH though.
Best,
B. Markoli
Dear Dr. Mathew,
Concerning electroless etch -I would probably try some ammonia-based etch with addition of hydrogen peroxide. It is really matter of sklil, experience and luck. You must be patient and try several series of experiments. I suggest to start with 10% ammonia with 1% of H2O2 for 20 seconds (room temperature, dipping). Then You will see the result and You will start play with ammonia concentration, ammonia /peroxide ratio, time of dip etc. observing better/worse result. Check properly the freshness of both chemicals - old bottles sometimes contains just "stinky water" :-). To be sure, use unopened new ones. Good luck!
Dear Dr. Mathew,
Since your samples are made of PLD its delicacy should be maintained to keep the sample in a good quality without any harm to its nature both physically and chemically. As far as I know a delicate etchant for copper materials developed by PLD is distilled water 50ml and Nitric acid 50 ml is a good etchant. Dissolve them in a disposable beaker and dip your samples for 30-45 seconds and rinse it immediately with normal tap water. I expect this to give you good results. Hope my answer was helpful.
Good Luck.
With Regards
Shiva S
Dear Dr. Mathew:
Then, if you have energy to try new test, it is possible to use the following etchant:
100 cc H2O
200 cc methyl alcohol
100 cc HCl
2gr CuCl2
7gr FeCl2
5cc HNO3
This formula is called Ralph's formula. Further information ca be reached in the paper in attachement. Seems that it can be used in a conventional ecth, but in the composition is clear the existence of great number of electrolytes, one of condictions to an efficient electropolishing.
In an alternative way, there are a set products designed to "cooper" ecth, see the patent (US5700389) attached.
Best regards
Marcos Nobre
Thanks a lot all for the creative etchant solution suggestions. Let me try them and see the results. Can anyone suggest some other etchant solutions and parameters for electropolishing as well?
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