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.

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

Pt deposited over region of interest Initial positioning of the trench to be dug around Pt bar Trench milled on either side of the ROI Electron Beam image of the Trench Milled Region Further thinning is carried out around ROI Marking the release cuts on the tilted sample Ion Milling of the marked region Electron beam image of the milled region Sample depth is shown in this electron image Probe affixed to the specimen edge by depositing a Pt blob Electron image of sample lifted out of the trench Final ion-beam thinning after liftout Ion-beam image of the electron transparent sample Electron beam image of the finally thinned sample

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