Scanning Particle-Beam Microscope Innovations

The work at the Scanning Particle-Beam Microscope Project is aimed at the development of the best-in-the-world scanning electron and ion microscopy and related dimensional metrology. This includes the exploration, invention and application of sophisticated methods to enhance this instrument’s capabilities such as: (1) advanced sample stages with high-speed, sub-nanometer-resolution laser interferometer measurements; such high-precision sample stages will allow active monitoring and ultimately active compensation control of stage and instrument vibration (a major contributor to loss of resolution through image blurring); (2) contamination-free, sub-nm resolution, high accuracy digital imaging that will fully take advantage of the focusing capabilities of the scanning electron microscope (SEM); (3) part of the work is the development of resolution standards and resolution measurement methods, which will place the characterization of this most critical of SEM performance metrics on a solid metrological basis and allow objective comparison between instruments and operating conditions; and (4) further activity of the Project is applied research and development of dual beam (ion/electron) imaging and metrology with a focused ion beam (FIB) as well as ion nano-milling.

The SEM is one of the workhorse techniques for imaging and characterization for nanotechnology. Significant improvements are still possible, and especially for nano-scale imaging and dimensional metrology. The work in the Project deals with all significant error sources and is aimed at finding the best performing solutions. Sophisticated measurement methods and advanced algorithms are under development, some of the have already proved to be superior to currently commercially available solutions. State-of-the-art instruments, superb laboratory and long-term expertise and excellent international cooperation are key to the success of the Project.

Helium Ion Microscope.

Beyond the research and development related to SEMs the Project will explore the metrological science of a revolutionary new particle beam technology called scanning helium ion microscopy (HeIM). HeIM is analogous to the SEM but uses a probing beam of He+ ions instead of electrons. This results in higher resolution and in greater surface-related information. The Project will work in collaboration with the manufacturer and SEMATECH and other NIST Laboratories to understand the science of He+ ion imaging and to optimize the instrument’s metrological capabilities. The Project will lead the work to develop a thorough understanding of the origin of the measured signal thus leading to accurate HeIM metrology.

• Developed He ion lithography and nanomilling methods with approximately 10 nm smallest fabricated structures. These are the finest features ever nanomilled, and open up new possibilities for innovation.
• Developed a strong cooperation with Zeiss regarding the optimization and implementation of HIM. NIST expertise is currently being used to improve the performance of the HIM to make it a viable alternative to SEM for nanotechnology and nanomanufacturing.