November 24, 2008: Carl Zeiss SMT says it has set a new record resolution benchmark for scanning electron and ion microscopy. By employing Zeiss’ Orion Helium-ion microscope, a surface resolution of 2.4Å (0.24nm) has repeatedly been achieved (25%-75% edge-rise criterion) on various samples, 3× better than the most sophisticated scanning electron microscopes are able to achieve today with the same surface sensitivity.
“This unmatched resolution for surface imaging with scanning electron and ion microscopes is extremely important for semiconductor manufacturers and many others who need to see small features that currently cannot be resolved,” said Nicholas P. Economou, SVP of Carl Zeiss SMT, in a statement.
The ongoing shrinkage of feature sizes of semiconductor devices — some IC layers have reached thickness of only a few atoms — makes extreme high-resolution microscopy mandatory, explained Rainer Knippelmeyer, SVP of operations, in a statement. “Semiconductor manufacturers are in dire need of reliable high-resolution, surface sensitive metrology and process control tools,” he said. “With the Orion Helium ion microscope we offer exactly the tool the industry and nanotechnology research needs and we continue to keep pace with the industry’s rapidly changing requirements.”
Image resolution of 0.24nm a linescan over the very sharp edge of an asbestos fiber on a thin holey carbon foil. The texture of the holey carbon foil demonstrates the extremely high surface sensitivity of the Orion, which equals or even exceeds the surface sensitivity of an SEM operated at 1kV and below. (Source: Carl Zeiss SMT)
The secret behind the extreme high resolution of the helium-ion microscope lies in the proprietary source technology and in the interaction between the scanning ion beam and the surface of the specimen. The source of the microscope is very small and the helium ions emanate from a region as small as a single atom. Unlike electrons, the helium ions have a very small wavelength and hence do not suffer appreciably from adverse diffraction effects — a law of physics which fundamentally limits the imaging resolution of electrons. Also, the helium ion beam triggers signals directly from the surface of the sample and stays very collimated upon entering the sample. This results in very sharp and surface sensitive images at the quoted resolution which can be easily interpreted.