wet clean after fin etch

[jensy]

After fin etch,on the fin sidewall,there is some thick reactive layers like SiOF SiCl……,I'd like to know how to clean them to get a good surface with low interface state density without influencing on Finfet device performance. Although I look up it on the web for a long time, I have't gotten some useful reference papers. Can you help me？
Thank you.

 

[nghanayem]

I don't have reference papers, and I am dry etch rather than wet etch, so the following suggestions will obviously be colored by that. Assuming your etch byproduct isn't just some particles of etch polymer (because if it was, I would try cyrokinetic cleaning); I would try a plasma dry-clean. Some plasma etchers are built around low ion densities to minimize surface damage. Dedicated plasma ashers have ion screens to further limit surface damage and are another option. They (ashers) are also cheaper than a fancy isotropic dry etcher with low ion densities. Either way you will leave less ions behind on the fin surface than with a wet etch, and that should do a good job preserving the electricals of your device. Using inerts for your dry clean should minimize leaving behind nastiness too. Also if I'm being honest I don't know why your fin etch would be leaving behind thick layers of SiOF and especially SiCl given the vapor pressures of these chemicals. I feel like a very good starting places is optimizing the etch/fiddling with the reactor chemistry to leave less etch byproduct on the wafer surface. This is at least what seems intuitive to me if I was in your shoes with the given information.

 

[jensy]

Thank you. To get relatively steep etched profile, there are some thick etched byproduct on the Fin sidewall and they are not easily to be removed. Maybe DHF is effective but it is still not enough and I hope much better solution can be used to get clean Fin surface.