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.

Thin-Film Ellipsometry Metrology



P. Durgapal, James R. Ehrstein, Nhan Van Nguyen


A wide variety of commercial ellipsometers are available in the market today. They all measure the change in the state of polarization of light on reflection, but the techniques adopted vary from instrument to instrument. Further, the models used to evaluate the thickness and refractive index of the oxide film during analysis of measurement data vary in complexity. The two main techniques of measurement are single wavelength ellipsometry and spectroscopic ellipsometry. The NIST Standard Reference Materials available today are based on conventional single wavelength ellipsometry. We discuss the challenges encountered in providing reference materials by using spectroscopic ellipsometry. First, the limits of conventional single wavelength ellipsometric determination of film thickness are investigated and then possible new technologies are explored. We present a discussion comparing the different types of instruments available and how their unique designs affect the accuracy of thickness determinations. Manufacturing, and accurate determination, of thickness of films this thin (<10 nm) is a challenging task. Results from independent ellipsometric measurements on two different types of instruments are compared for the case of ultra thin thermally grown silicon dioxide films on silicon crystal substrates. Stability curves for the thickness of thin dielectric films over a period of two years are also presented.
Proceedings Title
Proc., 1998 Conference
Conference Dates
March 23-27, 1998
Conference Location
Gaithersburg, MD, USA
Conference Title
Characterization and Metrology for ULSI Technology


dielectric film, ellipsometry, gate oxide, metrology, reference materials, silicon dioxide, thickness, thin films


Durgapal, P. , Ehrstein, J. and Nguyen, N. (1998), Thin-Film Ellipsometry Metrology, Proc., 1998 Conference, Gaithersburg, MD, USA (Accessed July 19, 2024)


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

Created February 28, 1998, Updated October 12, 2021