Scatterometry takes advantage of the sensitivity exhibited by optical diffraction from periodic structures, and hence is an efficient technique for lithographic process monitoring. A feature region measurement algorithm has been developed to extract accurately and quickly the relevant constitutive parameters from diffraction data. It is a method for efficiently determining grating structure by seeking the reflectance at some angles contains more information about the structure of the surface relief profile than the reflectance at other angles in a library data match process. The number of measurements and size of signature matching library will be reduced in a great percentage by performing the feature region algorithm.

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We propose using angular scatterometry as a means to investigate LWR (line-width roughness) and CD (critical dimension). The grating target is illuminated by a single wavelength light source which has large angular aperture both in incidence angle θ and azimuth angle φ . A preliminary scatterometry model was first built by assuming perfect critical dimension printed without any line-width roughness. The difference between the model prediction and actual measurement is cased by line-width roughness contribution. We developed a calibration curve as a function of line-width roughness based on the statistical quantity of the incidence and azimuth angle dependence. The results demonstrate that scatterometry can indeed be used to extract line-width roughness and critical dimension information in production line with nano-scale resolution.

As overlay tolerances of microlithographic technology become increasingly severe, conventional bright-field metrology systems are limited by image resolution and precision. Scatterometer (angular scatterometer or spectroscopic reflectometer, for example) has the advantages of good repeatability and reproducibility, and is proposed as an alternative solution for overlay metrology. Previous studies have applied a spectroscopic reflectometer, which is as function of incident wavelength, to overlay measurement. This work investigated overlay measurement by using an angular scatterometer, which is as function of incident angle. A focused laser spot was incident on linear grating, an overlay target. An angular signature, a 0 th -order reflective light beam, scattered from linear grating was measured when the incident and reflective angles were changed simultaneously. The overlay target consists of two linear gratings located on two different layers of a stacked structure, and the overlay error is the misalignment between these two different layers. The measured results using angular scatterometer (also known as the diffraction-based method) are compared with using the bright-field microscope (also known as the image-based method), which use a bar-in-bar target as an overlay target. Statistical data sets demonstrate that angular sctterometer has nearly one order better of repeatability and tool induced shift than conventional bright-field microscope. Additionally, a series of different parameters of overlay targets, such as different pitches, line-to-space ratios, and stacked structures is designed and manufactured. The sensitivity of overlay measurement of various linear grating targets is also measured and discussed.

We demonstrate that the tolerance of abrupt bending for a ridge-type Ti:LiNbO 3 waveguide is larger than that for the conventional one. All optical performances of the waveguides with different bending angles are simulated and compared by beam propagation method involving the Runge-Kutta algorithm.