By using electrons instead of light to investigate surfaces, SEMs routinely provide imagery at a resolution that exceeds the capabilities of optical microscopes by a couple orders of magnitude. The basic method of SEM involves an electron optics column directing an accelerated beam of electrons at the sample. The interaction of the sample with the primary electrons of the beam produces secondary electrons that are emitted from the sample. Detection of these electrons allows the image of the sample to be built up. Many SEMs also have additional x-ray detectors that provide compositional analysis.

A new dimension of SEM is opened up with the addition of a means to manipulate the sample within the sample chamber. One way to enable this is with a focused ion beam (FIB). The FIB provides a directed beam of ions. Typically, the ions used in an FIB are gallium due to the metal’s low melting point. A heated tungsten needle melts the gallium, and electromagnetic interactions ionize the gallium atoms, which are then emitted from the source. When the ion beam is directed at the sample, atoms of the surface are sputtered away.

Unlike SEM, FIB is inherently destructive. This enables manipulation of the sample. Probably the most common usage is to prepare the sample by cutting away material to expose a cross section, which can be imaged with the SEM to provide a fuller picture of the sample. Continued sectioning with the FIB allows each slice to be imaged, and the slices can be reconstructed into a 3-D image of the sample.

This ability to create thin sections also enables another important application—the preparation of samples for analysis by TEM. Since TEMs operate in transmission mode, the samples have to be thin so that electrons can pass through them. FIB and FIB-SEM are the main way these lamellae (as the thin sections are known) are produced.

The FIB can be used not only to remove material by sputtering but also to add material to the sample. When certain gases are introduced into the chamber, the interaction with the ion beam results in the deposition of material on the sample. Carbon and tungsten are common elements that are deposited, although gallium from the FIB is also introduced. Using this process, novel nanostructures can be created, or electrical connections on a component can be repaired or severed.

The most common application area for FIB-SEM is in the semiconductor and electronics industry, where it is used to analyze most of the nanoscale materials that support the industry, such as circuits and components. FIB-SEM is also becoming more prevalent in academic research, with interest from materials science disciplines. Other applications exist in nanotechnology, medical devices and other advanced materials research.

The major players in electron microscopy also dominate the market for FIB-SEM. Other market participants include Carl Zeiss and Tescan. The total 2014 market demand for FIB-SEM systems was about $200 million.

Combined FIB-SEM at a Glance:

Leading Suppliers

• FEI

• JEOL

• Hitachi High-Technologies

Largest Markets

• Semiconductor

• Academia

• Nanotechnology

Instrument Cost

• $750,000–$2.5 Million