The National Institute of Standards and Technology is developing a dimensional pitch standard covering the range 1 micrometers to 10 mm, intended for the calibration of microscope magnification and of dimensional metrology instrument scales. Called SRM 2800, Microscope Magnification Standard, it consists of symmetrical nested linear pitch patterns in decade ranges printed in one direction on a quartz microscope slide. The array of parallel lines is printed on a clear background to facilitate use in optical microscopes using transmission mode or reflection mode illumination. This pitch standard is also useful in atomic force microscopes, and in scanning electron microscopes and scanning tunneling microscopes when coated with a conducting film (although there are other standards from NIST which are more suitable for SEMs). It can be used to calibrate the scales of micromachining tools. The positions of the centers of the lines relative to the origin in the center of the pattern will be certified. The linewidths are not calibrated. While this standard facilitates accurate magnification and scale calibration, care must be taken when measuring the size (left edge to right edge, or linewidth) of an object. The appropriate definition for 'edge' becomes an important issue, and proximity effects and edge effects can become important when the required measurement uncertainty is less than the wavelength of the light used.
Proceedings Title: Proceedings of SPIE, Microlithography and Metrology in Micromachining II, Michael T. Postek, Jr., Craig R. Friedrich, Editors
Conference Dates: October 14, 1996
Conference Location: Austin, TX
Conference Title: Dimensional Metrology, Mask Making, and Imaging
Pub Type: Conferences
dimensional standard, microscope, NIST, pitch, scale