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NANOTECHNOLOGY UNDERGRADUATE EDUCATION - 2007

In Situ Real-time Atomic Scale Nanostructural Synthesis, Characterization and Modeling

FIB Lift-Out Method for Specimen Preparation:

The Focused Ion Beams are known for their versatility. They are used in imaging, ion induced deposition, gas assisted etching, implantation, milling etc. as described in the Introduction section.

Here we describe an important application of FIB in preparing samples with excellent positional accuracy and site specificity for Transmission electron microscopy and other high-resolution characterization techniques. Due to dual-beam FIB, TEM sample preparation from specific sites in state of the art materials like semiconductor devices has become much easier. We describe a very useful sample preparation technique called the FIB Lift-out method.

The FIB equipment used in the current project is a Nova 200 NanoLab that houses an ultrahigh resolution field emission scanning electron microscope and a precise focused ion beam generator. This enables the operator to view the milling process real-time and make necessary adjustments with immediate effect. A schematic diagram of the equipment used in the current project is shown below.

FIB-DualBeam

The lift-out technique, when carried out in the Dual-Beam FIB, allows real-time monitoring of the milling process using the built-in Scanning Electron Microscope. Samples can now be more easily extracted from the region of interest. This extraction process occurs over a number of steps as shown in the Image Slideshow below.

FIB Lift-Out Technique Slideshow

The major steps involved in this technique are briefly listed below:

1. Pt strip deposition over region of interest (ROI): to project ROI from Ga ion implantation and damage

2. Trench milling on both sides of ROI

3. Ion-milling the release cuts to the sample

4. Attach the OmniProbe to the specimen

5. Lift-out the specimen from the trench followed by final thinning

A slideshow detailing these stages can also be viewed by clicking the link below:
FIB-Lift_Out.ppt