Hi, Folks.
I am working on the ALD project to deposit Al2O3 on the Si wafer from TMA and Water.
I have struggled with the preparation of OH- terminated Si wafer.
I have both Si(1 0 0) and Si(1 1 1) wafers.
Some folks say here that the Si wafers have native SiO2 on the Si wafer surface when the Si wafer is exposed to atmospheric oxygen. The native SiO2 can be removed from the RCA cleaning or HF. Some folks say that there will be H- terminated Si wafer surface after cleaning HF. However, several article mentioned the preparation of OH-terminated Si wafer can be produced with DI water rinsing on Si(100) wafer, followed by dipping in a 5% HF solution. I searched many articles and I concluded that the best cleaning method for Si wafer is RCA cleaning. After cleaning Si with RCA cleaning, what will be the composition of the Si wafer surface?
I am so confused about how to prepare OH- terminated Si wafer. Al2O3 ALD deposition from TMA and Water requires OH-group on the surface. If there is -H group formed, the process get trouble, I think.
It would be highly appreciated if you folks share your opinion and advice.
Thanks,
Dear Youngjoon,
in my experience using silicon wafers (for AFM and other surface analysis), I was either using plasma- or ozone-treatment. In both cases, you will enrich the surfae with oxygen and increase the hydrophilicity.
Please find more information related to ozone here: Article UV/ozone-assisted tribochemistry-induced nanofabrication on ...
HF on the contrary will make your surface more hydrophobic, removal of oxides, hydroxyls...
Alternatively, prinanha acid can be used to get similar results as ozone treatment, all these treatments will clean the wafer surface (removal of organic contaminants) and increae hydrophilicity (hydroxyl, oxide groups etc.). Here is also a comparison between different treatments (HF etching, piranha acid, plasma treatment..)
Article Silicon wafer wettability and aging behaviors: Impact on gol...
In general, I would avoid the use of HF just out of safety reasons and if possible use alternatives, such as ozone, piranha, plasma or a combination of those (such as piranha). If you want to stick to RCA cleaning protocol with HF, you could do Step 1-2 and then use piranha acid, O3 or plasma as last treatment.
Alternatively, you can add a first cleaning with small amounts of detergent, Step 1 RCA and then use piranha acid, O3 or plasma as last treatment (to avoid HF treatment).
As e.g. piranha acid might also edge your surface, the best would be to follow a given protocol and I hope you can find a suitable information in the provided literature.
Best,
Marco
Lee, Sun S., Jae Y. Baik, Ki-Seok An, Yung D. Suh, Jin-Ho Oh, and Yunsoo Kim. "Reduction of incubation period by employing OH-terminated Si (001) substrates in the atomic layer deposition of Al2O3." The Journal of Physical Chemistry B 108, no. 39 (2004): 15128-15132.
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