Why Use the FIB?
The FB-2000A FIB has many capabilities that extend beyond those of other microscopy preparatory methods.
TEM Specimen Preparation of Bulk Specimens
Ultra-thin lamella for TEM analysis can be produced from bulk specimens with the FIB. Specimens that are less than 50–70 nm thick are difficult to prepare via other techniques, whereas the FIB, in capable hands, can produce a cross section of a micron-sized target area within a few hours.
Preparation of Bulk Specimens for SEM Analysis
During the first steps of TEM specimen preparation, a cross-sectioned wall of the bulk specimen is produced. After further polishing, the user can image that wall directly in the FIB or SEM.
Creation of Patterns
The FIB is equipped with a Nanometer Pattern Generation System (NPGS) which adds the capability of ion beam lithography, or constructing patterns onto specimens via specimen-ion beam interactions. Polygons may be fabricated into any shape, with up to almost 200 vertices, if desired. Additionally, each NPGS layer may be of different shape, thickness, magnification, dose, and current. This is often used in the ACMAL labs for the creation of wave guides.
Failure Analysis
By use of the FIB, users may view corrosion, signs of wear, fractures, and/or deformation in or on their specimens in three dimensions.
What Are the Specimen Constraints
Size
It is imperative that the user is aware of the dimensions of their specimens. There are several holders that will accommodate specimens, but none are larger than 5x10 mm. When the specimen is too thick—that is, over ~1 mm in thickness—the W deposition gun may strike the specimen or focusing may become impossible. When the specimen is too wide, trouble may arise when inserting the holder into the goniometer. All specimens should fit the 5x8x1 mm dimensions.
Conductivity
Use carbon tape whenever possible, and mill near the tape in order to dissipate the charge. It is not uncommon to coat specimens with carbon or tungsten to dissipate the charge, on the occasions when such coating does not affect the specimen.
Pre-preparation
If the feature of interest is buried in the specimen below 1 μm, the user may perform sputter coating with Au, Au/Pt, or Pt. If the feature of interest is close to or on top of the bulk specimen surface (<1 μm), the user should utilize carbon evaporation and sputter coating (in sequence) prior to W-deposition.
How Can I Eliminate Artifacts During TEM Specimen Preparation?
To avoid artifacts on the target area, be sure to use well-aligned beams and beam currents that are appropriate for each step of the process. Note that under high beam current conditions, there is a risk of re-deposition when sputtered material lands adjacent to the area being milled. Since high current beam conditions are routinely used during initial milling steps, it is a good idea to complete the process with low beam current conditions. As mentioned in other sections, it is advisable to utilize a small beam current for imaging the specimen, otherwise unintended milling can occur.