New reference material simplifies SEM performance checks. (News Briefs).The use of a new "sharpness" reference material from NIST (National Institute of Standards & Technology, Washington, DC, www.nist.gov) The standards-defining agency of the U.S. government, formerly the National Bureau of Standards. It is one of three agencies that fall under the Technology Administration (www.technology. combined with data from state-of-the-art inspection software could help make routine the currently difficult but critical task of running performance checks on scanning electron microscopes scan·ning electron microscope n. Abbr. SEM An electron microscope that forms a three-dimensional image on a cathode-ray tube by moving a beam of focused electrons across an object and reading both the electrons scattered by the object and , known as SEMs. All SEMs, whether they are in the laboratory or on the production line, slowly lose performance ability with use. Loss in image quality also means loss in measurement sensitivity. Contributing to SEM performance loss are a variety of factors including misalignment mis·a·ligned adj. Incorrectly aligned. mis  a·lign ment n. , contamination and increase in size of the primary electron beam. Measuring the loss in image sharpness is one way to identify this performance. An improved ability to assess SEM performance loss would be an important quality control advance for the more than $200 billion semiconductor industry because fully automated SEMs are used to inspect silicon wafers. NIST Reference Material 8091 is a small (approximately 2 [mm.sup.2]) diced semiconductor chip with tiny tower-shaped structures of silicon generated by a plasma-etching artifact commonly referred to as "grass." The fine-grained "towers" can be used to determine image sharpness at magnifications in excess of 100 000 times at both high- and low-accelerating voltages. RM 8091 can be mounted onto a wafer, wafer piece or specimen stub A small software routine placed into a program that provides a common function. Stubs are used for a variety of purposes. For example, a stub might be installed in a client machine, and a counterpart installed in a server, where both are required to resolve some protocol, remote procedure for insertion into a laboratory SEM or wafer inspection SEM. The chip also can be mounted onto a "drop-in" wafer. It is designed for use with Fourier analysis software such as the NIST/SPECTEL SEM Monitor Program, the NIST Kurtosis Kurtosis A statistical measure used to describe the distribution of observed data around the mean. Notes: Used generally in the statistical field, it describes trends in charts. program, the University of Tennessee The University of Tennessee (UT), sometimes called the University of Tennessee at Knoxville (UT Knoxville or UTK), is the flagship institution of the statewide land-grant University of Tennessee public university system in the American state of Tennessee. SMART program, or similar analytical techniques. The SEM Monitor is a collaborative effort by NIST, and industry. The SEM Monitor was honored in 1998 with an R&D 100 award from Research and Development Magazine. The system can make sharpness measurements on static, collected images or in real-time live mode, thus enabling users to easily adjust and align a CD-SEM CD-SEM Critical Dimension - Scanning Electron Microscopy or laboratory microscope to optimize performance. RM 8091 is available from the NIST Standard Reference Materials Program. Purchases of RM 8091 can be made by calling (301) 975-6776. RM 8091 also can be ordered online at www.nist.gov/srm. For technical information, contact Michael Postek, (301) 975-2299. Media Contact: John Blair, (301) 975-4261; john.blair@nist.gov. |
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