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Reference metrology for nanotechnology: significance, challenges and solutions
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Paper Abstract

Metrology and control of critical dimensions (CD) are the keys to the nanotechnology success. Modern nanotechnology and nanometrology are largely based on knowledge earned during the last 10-20 years of semiconductor technology development. Semiconductor CD metrology entered the nanotechnology age in the late 1990's. Work on 130 nm and 90 nm node technologies led to the conclusion that precision is an insufficient metric for metrology quality assessment. Other components of measurement uncertainty (MU) must be considered: (i) sample-to-sample measurement bias variation, (ii) sampling uncertainty and (iii) sample variation induced by probe-sample interaction. The first one (sample dependent systematic error) is common for "indirect" and model-based CD metrologies such as top-down and cross-sectional scanning electron microscopy (SEM) and optical scatterometry (OCD). Unless special measures are taken, bias variation of CDSEM and OCD could exceed several nanometers. Variation of bias and, therefore, MU can be assessed only if reference metrology (RM) is employed. The choice of RM tools is very limited. The CD atomic force microscope (AFM) is one of a few available RM tools. The CDAFM provides sub-nanometer MU for a number of nanometrology applications. Significant challenges of CDAFM remain: (a) probe finite dimensions are limiting characterization of narrow high-aspect spaces; (b) probe flexibility complicates positioning control; (c) probe apex sharpness limits 3D AFM resolution; (d) lifetime of atomically sharp probes is too short; (e) adsorbates change properties and dimensions of nanometer-sized objects considerably, etc. We believe that solutions for the problems exist. In this paper we discuss role of RM in nanometrology, current RM choices, challenges of CDAFM, and potential solutions.

Paper Details

Date Published: 24 August 2010
PDF: 15 pages
Proc. SPIE 7767, Instrumentation, Metrology, and Standards for Nanomanufacturing IV, 77670C (24 August 2010); doi: 10.1117/12.860666
Show Author Affiliations
Vladimir Ukraintsev, Nanometrology International, Inc. (United States)
Bill Banke, Consultant (United States)

Published in SPIE Proceedings Vol. 7767:
Instrumentation, Metrology, and Standards for Nanomanufacturing IV
Michael T. Postek, Editor(s)

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