Hostname: page-component-78c5997874-j824f Total loading time: 0 Render date: 2024-11-17T17:09:59.760Z Has data issue: false hasContentIssue false
  • English
  • Français

Comparison of Electron Imaging Modes for Dimensional Measurements in the Scanning Electron Microscope†

Published online by Cambridge University Press:  25 July 2016

Michael T. Postek ,
András E. Vladár ,
John S. Villarrubia  and
Atsushi Muto
Michael T. Postek*
Affiliation:
Engineering Physics Division, National Institute of Standards and Technology, 100 Bureau Drive, MS 8120, Gaithersburg, MD 20899, USA
András E. Vladár
Affiliation:
Engineering Physics Division, National Institute of Standards and Technology, 100 Bureau Drive, MS 8120, Gaithersburg, MD 20899, USA
John S. Villarrubia
Affiliation:
Engineering Physics Division, National Institute of Standards and Technology, 100 Bureau Drive, MS 8120, Gaithersburg, MD 20899, USA
Atsushi Muto
Affiliation:
Hitachi High Technologies America, Inc., 22610 Gateway Center Drive, Suite 100, Clarksburg, MD 20871, USA
*
*Corresponding author. [email protected]
Get access

Abstract

Dimensional measurements from secondary electron (SE) images were compared with those from backscattered electron (BSE) and low-loss electron (LLE) images. With the commonly used 50% threshold criterion, the lines consistently appeared larger in the SE images. As the images were acquired simultaneously by an instrument with the capability to operate detectors for both signals at the same time, the differences cannot be explained by the assumption that contamination or drift between images affected the SE, BSE, or LLE images differently. Simulations with JMONSEL, an electron microscope simulator, indicate that the nanometer-scale differences observed on this sample can be explained by the different convolution effects of a beam with finite size on signals with different symmetry (the SE signal’s characteristic peak versus the BSE or LLE signal’s characteristic step). This effect is too small to explain the >100 nm discrepancies that were observed in earlier work on different samples. Additional modeling indicates that those discrepancies can be explained by the much larger sidewall angles of the earlier samples, coupled with the different response of SE versus BSE/LLE profiles to such wall angles.

Keywords

metrologybackscattered electronslow loss electronssecondary electronsJMONSELelectron beam modeling
Type
Technique and Instrumentation Development
Information
Microscopy and Microanalysis , Volume 22 , Issue 4 , August 2016 , pp. 768 - 777
Copyright
© Microscopy Society of America 2016 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

†

Contribution of the National Institute of Standards and Technology; not subject to copyright.

References

Everhart, T.E. & Thornley, R.F.M. (1960). Wide-band detector for micro-ampere low-energy electron currents. J Sci Instrum 37, 246–248.Google Scholar
Moll, S.H., Healy, F., Sullivan, B. & Johnson, W. (1978). High efficiency, nondirectional BSE detection mode for SEM. SEM I, 303–310.Google Scholar
Moll, S.H., Healy, F., Sullivan, B. & Johnson, W. (1979). Further development of the converted BSE detector. SEM II, 149–154.Google Scholar
Monahan, K., Toro-Lira, G. & Davidson, M. (1993). A new low voltage SEM technology for imaging and metrology of submicrometer contact holes and other high-aspect-ratio structures. Proc SPIE 1926, 336–346.Google Scholar
Postek, M.T. (1990). Low accelerating voltage SEM imaging and metrology using BSEs. Rev Sci Instrum 61(12), 3750–3754.Google Scholar
Postek, M.T., Keery, W.J. & Frederick, N.V. (1990). Low profile high efficiency microchannel plate detector system for scanning electron microscopy applications. Rev Sci Instrum 61(6), 1648–1657.Google Scholar
Postek, M.T., Keery, W.J. & Larrabee, R.D. (1988). The relationship between accelerating voltage and electron detection modes to linewidth measurement in the SEM. Scanning 10, 10–18.Google Scholar
Postek, M.T. & Vladár, A. (2011). Modeling for accurate dimensional scanning electron microscope metrology: Then and now. Scanning 33, 111–125.Google Scholar
Postek, M.T. & Vladár, A.E. (2013). Does your SEM really tell the truth? How would you know? Part 1. Scanning 35, 355–361.Google Scholar
Postek, M.T. & Vladár, A.E. (2015). Nanomanufacturing concerns about measurements made in the SEM part IV: Charging and its mitigation. SPIE 9556, 95560Q1-11.Google Scholar
Postek, M.T., Vladár, A.E. & Cizmar, P. (2014 a). Nanomanufacturing concerns about measurements made in the SEM part III: Vibration and drift. SPIE 9173, 917306, 1–10.Google Scholar
Postek, M.T., Vladár, A.E. & Kavuri, P.P. (2014 b). Does your SEM really tell the truth? How would you know? Part 2. Specimen contamination. Scanning 36, 347–355.Google Scholar
Postek, M.T., Vladár, A.E., Ming, B. & Bunday, B. (2014 c). Documentation for reference material (RM) 8820: A versatile, multipurpose dimensional metrology calibration standard for scanned particle beam, scanned probe and optical microscopy. NIST Special Publication 1170. Available at http://www.nist.gov/manuscript-publication-search.cfm?pub_id=914808 CrossRefGoogle Scholar
Postek, M.T., Vladár, A.E., Wells, O.C. & Lowney, J.L. (2001). Application of the low-loss scanning electron microscope (SEM) image to integrated circuit technology. Part 1. Applications to accurate dimension measurements. Scanning 23(5), 298–304.Google Scholar
Reimer, L. (1985). Scanning Electron Microscopy Physics of Image Formation and Microanalysis. Heidelberg: Springer-Verlag. 457pp.Google Scholar
Reimer, L. & Tollkamp, C. (1980). Measuring the backscattering coefficient and SE yield inside a scanning electron microscope. Scanning 3, 35–39.Google Scholar
Sullivan, N. & Newcomb, R. (1994). Critical dimension measurement in the SEM: Comparison of backscattered vs. SE detection. Proc SPIE 2196, 118–127.Google Scholar
Villarrubia, J.S., Ritchie, N. & Lowney, J. (2007). Monte Carlo modeling of SE imaging in three dimensions. SPIE 6518, 65180K: 1–14.Google Scholar
Villarrubia, J.S., Vladár, A.E., Ming, B., Kline, R.J., Sunday, D.F., Chawla, J.S. & List, S. (2015). Scanning electron microscope measurement of width and shape of 10 nm patterned lines using a JMONSEL-modeled library. Ultramicroscopy 154, 15–28.Google Scholar
Villarrubia, J.S., Vladár, A.E. & Postek, M.T. (2005 a). Scanning electron microscope dimensional metrology using a model-based library. Surf Interface Anal 37, 951–958.Google Scholar
Villarrubia, J.S., Vladár, A.E. & Postek, M.T. (2005 b). A simulation study of repeatability and bias in the CD-SEM. J Microlith Microfab Microsyst 4, 033002-1.Google Scholar
Wells, O.C. (1970). New contrast mechanism for scanning electron microscope. Appl Phys Lett 16(4), 151–153.Google Scholar
Wells, O.C. (1971). Low-loss image for surface scanning electron microscope. Appl Phys Lett 19(7), 232–235.CrossRefGoogle Scholar
Wells, O.C. (1986). Low-loss electron images of uncoated photoresist in the scanning electron microscope. Appl Phys Lett 49(13), 764–766.Google Scholar
Wells, O.C. (1987). Low-loss electron images of uncoated non-conducting samples in the scanning electron microscope. In Microbeam Analysis, Geiss, R.H. (Ed.), pp. 76–78. San Francisco, CA: San Francisco Press.Google Scholar