Subnanometer wavelength metrology of lithographically prepraed structures: a comparison of neutron and X-ray scattering.

Abstract

The challenges facing current dimensional metrologies based on scanning electron microscopy (SEM), atomic force microscopy (AFM), and light scatterometry for technology nodes of 157 nm imaging and beyond may require the development of new metrologies. We provide results of initial tests of a measurement technique based on Small Angle X-ray Scattering (SAXS) capable of rapid measurements of test samples produced using conventional test masks without significant sample preparation. Using a sample photoresist grating, the technique is shown to apply to both organic, including photoresist, and inorganic patterns, including metal and oxide. The sub-Angstrom wavelength provides nanometer level resolution, with significant room for increased resolution. SAXS provides a dramatic improvement over the use of small angle neutron scattering (SANS) in measurement resolution. An additional advantage is the potential of developing a SAXS-based metrology tool on a laboratory scale.