FIB SEM Ga or Xe

The Focused Ion Beam or FIB is an instrument which focuses and scans an accelerated ion beam on a sample in a vacuum chamber. Such a column can be used for two main purposes:

  • To form scanning ion images by collecting the secondary electrons (SE) generated by the interaction of the incident ions and the sample surface.
  • To locally sputter the material surface to directly fabricate arbitrary nanostructures.

 The most commercially available FIB systems are using gallium (Ga) ions for micromachining of the surfaces.

During the last 25 years, FIB instrumentation has become a key technology for wide fields of materials science applications, from circuit editing to Transmission Electron Microscopy (TEM) sample preparation, microstructural analysis and prototype nanomachining. Associated with a SEM (Scanning Electron Microscope), FIB instruments have become a powerful tool for nano-manipulation and nano-fabrication when coupled with micromanipulators. Equipped with a Gas Injection System (GIS) nanometric local deposition (using the GIS) can even be obtained.
 

Applications

Specimen preparation for Transmission Electron Microscopy (TEM) analysis

An important application of FIB is specimen preparation for Transmission Electron Microscopy (TEM). TEM require really thin samples, less than 100 nanometers thick. Other techniques can be used, but FIB fits perfectly to locate with a nanometric resolution the interesting area on the sample. 
 

Realization of a cross section for Scanning Electron Microscopy (SEM) observation

Another application of FIB is to realize a cross section, to look at the structure and the chemistry of the sub-surface in a more simple way than with TEM. When the dimensions of the considered layers / structures are convenient, SEM can already provide great informations. 


Micro and nano machining, material deposition

FIB is also used as a tool for micro production, to change or work on the material on a micrometric or nanometric scale.
A FIB can also be used to deposit materials. We talk about IBID for Ion Beam Induced Deposition. It is a chemical-vapor-deposition (MCVD) assisted by FIB which happens when a gas such as tungsten hexacarbonyl (W(CO)6), introduced into the vacuum chamber is adsorbed by the sample. Swipping out a sample area with the ion beam, the gas is decomposed and the tungsten, non volatil, stays on the surface of the sample. The tungsten  layer deposited protects the sample from gallium spraying. Other kind of metals like tungsten, such as platinium, can also be deposited with the same kind of process.

 
FIB SEM Ga or Xe
A cross-section of a solder ball milled from the board side