National Nano Engineering Conference Preview

Helium Ion Microscopy (HIM) is a new, potentially revolutionary imaging and particle beam measurement methodology. The first commercial HIM has been installed at the National Institute of Standards and Technology in Maryland. Dr. Michael T. Postek is the Chief of the Precision Engineering Division and Program Manager of the Nanomanufacturing Program in the Manufacturing Engineering Laboratory (MEL) at NIST, and is a 2007 Nano 50 winner in the Innovator category. A research program within MEL will study the imaging mechanisms, modeling, analytical capabilities, and uncertainties regarding dimensional measurements made with this microscope.

This methodology presents an potentially revolutionary approach to measurements that has several potential advantages over the traditional scanning electron microscope (SEM) currently in use in research and manufacturing facilities across the world. The HIM is unique but also complimentary to the traditional SEM. Due to the very high source brightness, and the shorter wavelength of the helium ions, it is theoretically possible to focus the helium ion beam into a smaller probe size relative to that of an electron beam of an SEM, so higher resolution is possible. In an SEM, an electron beam interacts with the sample and a variety of signals is generated, collected, and imaged. This interaction zone may be quite large, depending upon the electron energy and sample material. Conversely, when the helium ion beam interacts with the sample, it does not have as large an excitation volume and thus, the image collected contains more surface-related information and can potentially provide atomic resolution images on a wide range of materials.

The current suite of HIM detectors can provide information on topographic, material, crystallographic, and electrical properties of the sample. Compared to an SEM, the secondary electron yield is quite high, allowing for imaging at extremely low beam currents. The relatively low mass of the helium ion, in contrast to other ion sources such as gallium, results in no discernable damage to the sample.

Learn more about NIST’s Helium Ion Microscope from Dr. Postek in the Advances in Imaging/Microscopy Session at 11:00 am on Thursday, November 15.