Yesterday in Tulsa went very well. Despite the e-beam technician being on vacation until next week I have still been able to make some good strides in sample preparation. The AFM tech at TU had some trouble getting a good PMMA layer depth reading on the samples from last week. He said they were in the neighborhood of 50 nm, which is about a third of what we were expecting based on the notes of the students previously working on this type of set up. I have found some other protocols online that suggest that 50 nm is actually right on the money. It was stated in the proposal that as long as the wall height was 20 nm or more it should not affect the surfactant adsorption, and the lower the wall height the less it will interfere with the AFM tip when gathering images after surfactant adsorption so 50 nm is actually really good. I'm a tad nervous because the PMMA solution they have had me using at TU was the same that the group before me was using, which has an expiration date about 4 years ago. However, it should not cause problems for the purposes we need it for.
I have some trouble making sure that the silicon pieces are microscopically smooth (using the right cleaning solution as well as a plasma cleaner) and this may be what's causing the small imperfection that can be seen in the film. The debris causing a wake pattern on the surface during the spin coating and I'm not sure it's a problem at this point as we can choose which area to use for the formation of trenches.
I will be returning next Thursday to continue the work and the e-beam tech should be back and we can see if we can get some trenches made!
On the other side of the project, I will be meeting with the OU researcher who has been helping me with nanosphere lithography and discuss the SEM micrographs and hopefully the week after we can try another run of etching with smaller spheres!
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