Focussed ion beam milling at grazing incidence angles

Area of Science:

• Materials Science
• Microscopy
• Nanotechnology

Background:

• Conventional focused ion beam (FIB) milling for cross-sectioning has limitations including redeposition, shadowing, and image distortion.
• Ion beam positioned perpendicular to the sample surface requires bulk material removal, limiting imaging area and efficiency.

Purpose of the Study:

• To present a new grazing incidence geometry for combined scanning electron microscope (SEM) and FIB instruments.
• To overcome limitations of conventional perpendicular ion beam milling for micro- and nanopatterning and cross-sectioning.

Main Methods:

• Samples are pre-trimmed using a microtome to create a sample block face parallel to the ion beam.
• Grazing incidence geometry is employed for fine polishing of selected areas of interest.
• SEM imaging is performed by tilting the sample surface perpendicular to the electron beam.

Main Results:

• Eliminates the need for bulk material removal by the ion beam.
• Avoids common limitations such as redeposition, shadowing, and image distortion.
• Reduces milling time and enables larger cross-sectional areas for imaging.
• Provides geometrically undistorted electron images.

Conclusions:

• The grazing incidence approach is suitable for microtome-compatible materials under ambient and cryogenic conditions.
• This method offers significant advantages for biological and food sample analysis.
• The technique improves efficiency and image quality in SEM-FIB applications.