FIBbed

I'm spending most of my week trying to make a FIB sample to take with me to the synchrotron next week. The FIB is in a class 100 clean room, so I have to wear one of those bunny suits all day. Unfortunately, we lost the first two tries, so I'm working on a third section. I have one last session scheduled for Friday, so hopefully the third time's a charm.

The FIB works by sputtering away the sample with an ion beam. I can tell the FIB to dig out trenches around an area of interest to create a 1 micron thick flat section. But then comes the hard part! I have to take this tungsten needle and gently touch it to the top of the section (much harder than it sounds), make a platinum weld between the needle and section, cut out the bottom of the section, detaching it from the rest of the sample, and then bring the released section over to a TEM grid, weld it into place there with Pt, and then cut the needle free. After all that nerve-wracking manipulation, it's trivial to mill the section down to ~100 nm, where it becomes transparent to electrons.

The first sample we lost trying to touch it with the needle (not my fault, I wasn't operating the FIB then). It wasn't aligned properly, and it ended up prying the FIB section free, whereupon it flies off into the ether of the instrument, never to be seen again. The second time we picked up the section and brought it over to the TEM grid, but it charged up during the second Pt welding and flew off.