By Helen Fawcett
The Boston University Photonics Center’s newest shared facility, the FIB/TEM Facility (FTF), is located in basement (B11C) of the Photonics Center. The newest tool was purchased through the Materials Science and Engineering Division and is open for training and use to the Photonics and Material Science and Engineering groups at Boston University. This tool, the FEI Quanta 3D FEG (field-emission gun) Dual Beam FIB (Focused Ion Beam combined with a Scanning Electron Microscope), is shown below.
With many features not found on typical FIB systems, it is a versatile high-resolution, low vacuum SEM/FIB for 2D and 3D material characterization and analysis. The instrument is unique in the Boston area as no other facilities have a comparable FIB with capabilities for nanoscale preparation and analysis of materials. The field-emission electron source has much higher brightness making it ideal for high resolution SEM imaging of nanostructures. With the FEG source, the best resolution is 1.2 nm in the HiVac mode and 2.9 nm in the LoVac mode. For more information on the features of the FIB, you can visit the FTF website at http://www.bu.edu/photonics/sharedfacilities/fibtem-facility-ftf/.
Some of the current users have been able to etch 50 nm trenches several hundred nanometers deep and deposit metals such at Platinum with high accuracy. David Bishop’s Solid State Laboratory has been using the FIB for high resolution imaging, etching parameters and platinum deposition. The video function has been used to show how the milling etches through multiple materials. This allows for precision customization of MEMS devices on the sub 100 nm scale. As Professor Bishop (MSE/ECE/Physics) once said, when there is some residual oxide preventing the MEMS structure from deflecting, once you place the sample in the FIB, it is almost like you are pointing your finger to a specific location, aligning the beam and within seconds that previously useless device becomes a fully functioning structure. Beyond adjusting the mechanical properties by milling the MEMS structures, the FIB can also be used for laying down platinum electrodes and even sub-micron welding. Matthias Imboden, Professor Bishop’s postdoctoral researcher and one of our first self-users on the FIB provided some exceptional pictures of his structures in the FIB. More information about training and the use of the FIB can be obtained by contacting Alexey Nikiforov (firstname.lastname@example.org), the Laboratory Manager of FTF.