Study on Microgratings Using Imaging, Spectroscopic, and Fourier Lens Scatterometry

Abstract

With new fabrication methods for mass production of nanotextured samples, there is an increasing demand for new characterization methods. Conventional microscopes are either too slow and/or too sensitive to vibrations. Scatterometry is a good candidate for in-line measuring in an industrial environment as it is insensitive to vibrations and very fast. However, as common scatterometry techniques are nonimaging, it can be challenging for the operator to find the area of interest on a sample and to detect defects. We have therefore developed the technique imaging scatterometry, in which the user first has to select the area of interest after the data have been acquired. In addition, one is no longer limited to analyze areas equal to the spot size, and areas down to 3 μm × 3 μm can be analyzed. The special method Fourier lens scatterometry is capable of performing measurements on misaligned samples and is therefore suitable in a production line. We demonstrate characterization of one-dimensional and two-dimensional gratings from a single measurement using a Fourier lens scatterometer. In this paper, we present a comparison between spectroscopic scatterometry, the newly developed imaging scatterometry, and some state-of-the-art conventional characterization techniques, atomic force microscopy and confocal microscopy.