FIB Sample Preparation of Polymer Thin Films on Hard Substrates Using the Shadow-FIB Method

Focused ion beam (FIB) instrumentation has proven to be extremely useful for preparing cross-sectional samples for transmission electron microscopy (TEM) investigations. The two most widely used methods involve milling a trench on either side of an electron-transparent window: the “H-bar” and the “lift-out” methods [1]. Although these two methods are very powerful in their versatility and ability to make site-specific TEM samples, they rely on using a sacrificial layer to protect the surface of the sample as well as the removal of a relatively large amount of material, depending on the size of the initial sample. In this article we describe a technique for making thin film cross-sections with the FIB, known as Shadow FIBing, that does not require the use of a sacrificial layer or long milling times [2]. In this technique, the corner of a sample is positioned at an angle of incidence between the ion and electron beams in a dual-beam FIB, but not normal to either beam. As seen in Figure 1, the thin film is positioned such that it is in the FIB Sample Preparation of Polymer Thin Films on Hard Substrates Using the Shadow-FIB Method