“Lift-out” FIB-TEM Specimen Preparation Technique
- Practical Electron Microscopy and Database -
- An Online Book -

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This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
 

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The procedure of “lift-out” FIB-TEM specimen preparation technique is:

          i) Mechanically cut a piece of materials from a sample to fit inside FIB chamber.

          ii) Coat a conductive layer, such as carbon (C), chromium (Cr), or platinum (Pt), to prevent charging if the surface of the sample is insulator.

          iii) Mount the sample on a stub.

          iv) Load the stub together with the sample into FIB.

          v) Deposit a metal line on the area of interest (AOI) to prevent damage on the top portion of the specimen from sputtering. Typical dimensions of the metal line are 1~2 µm wide × 5~30 µm long × 2~3 µm high.

          vi) Cut a large stair-step trench on one side of the AOI with high Ga+ beam current.

          vii) Cut a rectangular trench on the other side of the AOI.

          viii) Tilt the sample to an angle greater than 45°.

          ix) Cut the bottom, left side, and a portion of the right side of the specimen.

          x) Tilt the sample back to its starting position (at 0° of angle).

          xi) Reduce the beam current to perform milling on each side of the specimen to reduce redeposition of sputtered material onto the surface of the specimen.

          xii) Clean the specimen by further reducing the beam current until the membrane is thinned to < 100 nm. The final thickness of the specimen will depend on the information you need and the density of the material(s).

          xiii) Remove the bulk sample from the FIB vacuum chamber.

          xiv) Put the bulk sample under a light optical microscope that has an objective lens with a large working distance.

          xv) Insert a sharp tip (~20–30 µm in size) into the arm of a hydraulic micromanipulator.

          xvi) Lift out the electron transparent membrane from the bulk sample by using the micromanipulator.

          xvii) Place the membrane onto a carbon- or formvar-coated Cu TEM mesh grid. In this step, the membrane is lifted out by electrostatic forces.

One clear disadvantage of this "lift-out" technique is that this technique does not permit further thinning if the prepared TEM specimen is too thick.

 

 

 

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