I had the opportunity the other day to do a bit of an experiment by “nano-machining” with ion beams. I wanted to drill shapes into the surface of an Eponate block with hippocampus tissue samples in it. The trick was the holes had to be as small as possible. Fortunately, I have access to an Focused Ion Beam milling machine down at the nano-fab facility on campus. With help from Randy Polson and Ian Harvey, we were able to do our experiment. Another week or so and we’ll know whether the experiment worked for our specific question. In the meantime, there are cool images to share.
What you see in the above two images are scanning electron microscopy images of carbon tape around our block sample. The hope was that the carbon tape would help dissipate the charge from the surface of the block, allowing us to maintain the structure of the ion beam. It turns out, we had to carbon coat everything as the tape was not enough. But again, cool images.
The first drill hole is about 5 micrometers deep and 10 micrometers across. With rare gas in the chamber, the hole appeared clean with minimal heating around the edges. The image itself looks reminds me of the surface of another planet with sand dunes in the bottom of a crater.
The next shape was an experiment designed to see if we could machine an angle. This was also performed with rare gas in the chamber and it gave beautiful results, machining a ~6.5 micrometer deep angled trench. You can even see the “dunes” in the bottom which are the tracks from the ion beam.