<title>Quantitative Sub-Micrometer Linewidth Determination Using Electron Microscopy</title>

Certification of SRM 1960 - Nominal 10 micrometer diameter polystyrene spheres (space beads)

“…The MEM system is based on a commercial ultra-high vacuum scanning electron microscope (SEM) with a field-emission electron gun [ 12 ]. In the MEM, the electron beam is fixed in position, so that it acts as a reference point or cross hair.…”

“…9 ). Displacement of the stage is monitored by a commercial heterodyne interferometer system which uses a stabilized helium-neon laser to set the metric [ 12 ]. In this way, the MEM measurement of the microsphere diameter is directly tied to the wavelength of the helium-neon laser (≈632.8 nm).…”

“…10 , this detector consists of a small aperture placed in front of a scintillation detector. When the angular size ( β ) of the aperture, as measured from the specimen, is equal to or smaller than the angular size ( α ) of the electron beam, the detector will only produce a significant signal if the beam does not scatter from the specimen [ 12 ]. In the present case, the aperture was about 1.5 mm in diameter, which corresponds to an angular size of 3.5 mrad.…”

Length and dimensional measurements at NIST

“…NBS has made fundamental contributions to the evolution of dimensional measurements over the period since the founding of NBS to the era of current work, which reaches back to the beginning of the last decade of the twentieth century. These fundamental contributions include: Introduction in 1922 of interferometric measurements of precision gage blocks [ 13 ] Development in 1961 of high-stability precision gage blocks [ 6 ] Creation in 1968 of the first scanned probe topography measuring instrument, a field-emission device that was the precursor of the scanning tunneling microscope and that was cited in the Nobel Prize award for that device [ 14 ] Development in 1976 of the technique for the low-uncertainty optical-microscope measurement of microelectronic photomask linewidths [ 15 ] Development in 1977 of the technique of computer-based real-time correction of systematic errors in positioning of coordinate measuring machines [ 16 ] Development in 1981 of the technique for laser-interferometer-based scanning-electron-microscope measurement of microelectronic photomask linewidths [ 17 ] …”

“…Development in 1981 of the technique for laser-interferometer-based scanning-electron-microscope measurement of microelectronic photomask linewidths [ 17 ]…”