- we use (Tridecafluoro-1,1,2,2-tetrahydrooctyl)trichlorosilane; 97% from abcr
- evaporation silanization was performed in an exsiccator which has been flushed with Ar prior to evacuation to drive out humidity | duration: 30 min | pressure: < 5 mbar | silane volume used: 40 µl
- the unwanted silane cross-linking was likely induced by humidity either in the exsiccator or in the silane bottle itself
- the pattern the Si wafer carries is an etched one
- I know that oxygen plasma should be able to remove the silane, but will it leave the patterend Si wafer unaffected? Will it also clean thoroughly within the channels of the pattern? Are there alternative ways?
HI, your procedure/question is not clear.
* How was the "wanted crosslinking" achived. Atmospheric humidity is neccessary to perform the siloxanisation. The procedure in the exsiccator depending on the pretreatment of the wafer (water can be adsorbed) leads to adsorbed layer of silanes which react under atmosphere (HCl catalyse the reaction) to form the siloxanes
* You will find intersting information within my articles with Walid Munief and the one about siloxanisation.
The silanization reaction with your surface is a condensation reaction which results in a covalent oxide bond to the surface. If the surface has a native oxide layer then O2 plasma will not likely remove the entire molecule that was deposited (depends on the plasma power) but will leave a monolayer of SiO2 after breaking the C-C or the Si-C bonds of the linker chain.
Plasma is largely a line of sight operation and it's efficiency down in deep channels starts to drop off pretty quick (depends on the lifetime of reactive moieties in the plasma). Whether the plasma damages your pattern or not will depend on the composition of the pattern. If the pattern is photoresist, It'll be toast. If the pattern is SiO2, it'll probably be just fine.
As an alternative to plasma, you could try HF etching. This will attack the Si-O bonds and release the entire molecule. If you have a pattern on top of native oxide, this won't work for you since you'll likely damage any oxide layers and any layers above.
Best of luck!
The most mild way to break the chemical bonding is to immerse in 1M NH4OH (ammonia solution) for about 48 hours at room temperature. The silane way stay physically bonded and brief sonication in alcohol water should physically remove. For background see: https://www.gelest.com/themencode-pdf-viewer/?file=https://www.gelest.com/wp-content/uploads/Hydrophobicity-Hydrophilicity_and_Silane_Surface_Modification.pdf
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