Hello,

have you tried HF? It should be ok for the Si too (if you do not want any oxidized layer on top of it). Or you could try (if you have at your disposal) a plama etcher with an appropriate pattern masking of course, if needed.

Bests,

Ivan

Ivan Sinicco , HF does not corrode nitride, and I am looking for a chemical route because I have very few plasma gases in the lab. But thanks for answering!

Give a look here...

http://jes.ecsdl.org/content/148/3/F43.abstract

Ivan Sinicco Oh, you were talking about a solution of HF and phosphoric acid. It was of great help, I will look at this route

thanks!

You can use BHF (buffered HF) solution or diluted HF (1:10 in DI water). The etching rate is relatively low depending on the SiNx thickness.

Goog Luck

Nice Contribution Ivan Sinicco

which mask (as appropriate pattern) is better for silicon nitride etching in phosphoric acid? when a silicon nitride layer is deposited on SiO2 layer. photoresist or metal?

Hello,

both of the silicon nitride and silicon can be etched by hot concentrated phosphoric acid and their etch rate are influenced by temperature and the concentration of phosphoric acid. Change these two factors might be helpful for improving the selectivity of silicon nitride to silicon. But since there are no specific infomation in your about the factors, I cannot assure if my suggestion could help you.

Hello,

Dear Zihan Zhou, you are right. But I mean mask or photomask for silicon nitride etching. What is your suggestion? Do you have any experience with this?

Hello,

Dear Azizmorad Koushki, I'm sorry I didn't try any mask for silicon nitride etching. I'm not very familiar with something about the mask or photomask. What I studied was mainly about the etching solution. But I guess an extra mask on Si like a thermal oxide layer might be useful, though it might be more challenging for processing.