Just as test pilots push planes to explore their limits, researchers at the National Institute of Standards and Technology (NIST) are probing the newest microscope technology to further improve measurement accuracy at the nanoscale. Better nanoscale measurements are critical for setting standards and improving production in the semiconductor and nanomanufacturing industries.
This new microscope technology uses helium ions to generate the signal used to image extremely small objects, a technique analogous to the scanning electron microscope, which was first introduced commercially in the 1960s. Paradoxically, although helium ions are far larger than electrons, they can provide higher resolution images with higher contrast. The depth of field is much better with the new technology too, so more of the image is in focus. It is the physics, explains Andras Vladar, SEM project leader in NISTs Nanoscale-Metrology Group. Ions have larger mass and shorter wavelength than electrons, so they can be better for imaging. The images, he says, appear almost three-dimensional, revealing details smaller than a nanometerthe distance spanned by only three atoms in the silicon crystal.
NIST is working to understand the imaging mechanisms of this new technology. The clearest advantage of the helium ion microscope is that the images show the actual edge of a sample better than the SEM, which is critical in precision manufacturing. Meeting critical dimensions by knowing where an edge is in high-tech manufacturing can mean the difference of hundreds of dollars per piece, explains Michael Postek, chief of the NIST Precision Engineering Division and the nanomanufacturing program manager. Semiconductor manufacturers have multi-million dollar scanning electron microscopes all along their production lines to help control their microchip manufacturing processes.
NIST received the first-ever commercial helium ion microscope, called Orion, from Carl Zeiss, In
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National Institute of Standards and Technology (NIST)