I am trying to fabricate a TFT with back gate structure.
After depositing and patterning TiN back gate structure, a HfO2 film was deposited by ALD. The next step is etching the HfO2 and patterning it.
Could you please give me some suggestions about how to pattern the HfO2 film without etching the TiN.
Other suggestions are also appreciated, if you have experience about the selectively etching HfO2 film with other metal materials.
Hi,
I have not etched HfO2, but I worked with Carbon on gold. I successfully etched carbon layer from gold surface without affecting the layer underneath using ns pulsed Nd:YAG Laser.
If you can optimize the fluence for HfO2, you can use it for HfO2 or infact for any material.
http://www.sciencedirect.com/science/article/pii/S0169433213012865
@Amol Singh Thanks for your reply, it is a good idea using laser etch. But the thickness of the HfO2 we use is about 30nm, we want to accurately control the etching rate.
Maybe HfO2 is too hard to etch by laser.
@Jiabin Wang May be you are right since I dont have experience with HfO2. But still If the absorption is different in HfO2 and TiN, I think you can use this technique, you have to optimize laser fluence for HfO2.
Dry etching of HfO2 is pretty difficult since the vapour pressures of HFF4 and HfCl4 are low. The best way is to wet chemical etch in dilute HF or buffered oxide etch. I don't know what selectivity you will get to TiN but this is quite stabile and you normally need a dry etch to remove TiN. IMEC did get good slectivity of HfO2 to SiO2 by using HF/BOE etch in a non-water based but polar solvent (e.g. alcohol). You might try this as well. This article can be found on the Internet.
@Peter Knapen Thanks for your suggestions. Now, we have tried etch HfO2 film by Reactive Ion Etch in NE550 system, using Cl2 and Ar as reactive gases. With carefully controlling the etching time, we can successfully etch HfO2 film, even there was some over etch on the surface of TiN film. Fortunately, the over etch didn't affect the conductance of TiN film.
Hello Jiabin,
Good to hear you can dry etch with good selectivity to TiN using Ar/Cl. Good luck with your project.
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