Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Toward Accurate Measurements of Pitch, Height, and Width Artifacts with the NIST Calibrated AFM



Ronald G. Dixson, Theodore V. Vorburger, P Sullivan, V W. Tsai, T Mcwaid


Atomic force microscope (AFM) measurements are being used increasingly for metrological applications such as semiconductor process development and control. Common types of measurements are those of feature spacing (pitch), feature height (or depth), and feature width (critical dimension). If high accuracy is required, the scales of an AFM should be calibrated. Presently, available standards for this purpose are calibrated using stylus instruments and optical techniques. The effectiveness of this approach, however, is limited by the differences in the full ranges of the various techniques and by questions of methods divergence. As the repeatability of many commercial instruments continues to improve, the importance of accurate calibration standards will increase. In order to calibrate AFM standards using an AFM, we have designed and built a metrology atomic force microscope, called the calibrated AFM (C¿AFM). This instrument has metrology traceable to the wavelength of light for all three axes. To realize this, a flexure translation stage, heterodyne laser interferometers, and a digital-signal-processor based closed-loop feedback system are used to control the x¿y scan motion. The z¿axis translation is accomplished using a piezoelectric actuator with an integrated capacitance sensor, which is calibrated using a heterodyne laser interferometer. Since the design of this instrument has been discussed in more detail elsewhere, we focus here primarily on the results of performance testing of the C¿AFM for pitch, height, and width measurements.
Proceedings Title
Proceedings of American Society for Precision Engineering
Conference Location


AFM, linewidth, metrology, pitch, step height


Dixson, R. , Vorburger, T. , Sullivan, P. , Tsai, V. and Mcwaid, T. (1996), Toward Accurate Measurements of Pitch, Height, and Width Artifacts with the NIST Calibrated AFM, Proceedings of American Society for Precision Engineering, , USA (Accessed June 23, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created December 31, 1995, Updated October 12, 2021