I have inherited a substrate preparation process from past graduate students. We have an ICP RIE and RIE plasma etching system.
We put a cleaned (IPA and Acetone washed) SiO2 wafer (90 nm SiO2, 500 um thick) in the etcher on RIE with no photoresist or precursor. There should be no patterning, the group called it oxygen-plasma cleaning. I was told that it leaves a grid-like pattern on the substrate, its a "randomized" vertical etch ? The power is 20 watts for 90 seconds, that would break through the oxide-layer with that power, right?
I am unsure of the actual effect, I was led to believe that it organizes precursor on the surface. The precursor-layer is many micron thick I don't see how this organizes the precursor.
Please link any relevant papers that may relate. Thank you!
Dear friend Anthony Butler
The RIE process you described is commonly used to create a hydrophilic surface on silicon wafers for CVD purposes. The oxygen plasma breaks through the native oxide layer on the surface, creating a roughened surface with hydroxyl (-OH) groups, which are highly reactive and attract water molecules, resulting in a hydrophilic surface.
The grid-like pattern you mentioned is likely due to the use of a randomizing gas (such as helium) during the RIE process, which helps to create a more uniform etch across the substrate. The power and duration of the RIE process depend on the thickness of the oxide layer and the desired surface roughness.
As for the effect of the RIE process on precursor organization, it is possible that the roughened surface created by the RIE process can help to anchor the precursor molecules and promote their organization. However, the thickness of the precursor layer may limit the effect of the RIE process on precursor organization.
Here are some relevant papers that may provide more information:
- "Plasma Processing for Hydrophilic Surface Treatment of Silicon Substrates" by B. R. Kim, et al. (Journal of Nanoscience and Nanotechnology, 2011)
- "Hydrophilic surface modification of silicon substrates using a high-density plasma source" by H. Lee, et al. (Journal of Vacuum Science & Technology A, 2005)
- "Modification of surface wettability of silicon substrates by plasma treatment" by H. J. Lee, et al. (Applied Surface Science, 2004)
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