Performance study of CD mark size for angular scatterometry

Ku, Yi-Sha; Pan, Ding-Sheng; Wang, Shih-Chun; Tung, Chiou-Kou; Ko, Chun-Hung; Lu, Sheng-Hua; Smith, Nigel

doi:10.1117/12.599188

Cited by 1 publication

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“…The results indicate nanometer-level sensitivity of the technique for the targets investigated. Given that dedicated angle-resolved scatterometry instruments routinely achieve sensitivity to line width in the sub-nanometer range, 8 it is reasonable that with proper control over the light source and a wellcharacterized transfer function through the optics, the current technique could be applied to a wide range of targets with good sensitivity. …”

Section: The X-error Bars Shown Inmentioning

confidence: 99%

Scatterfield microscopy using back focal plane imaging with an engineered illumination field

et al. 2006

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We have implemented back focal plane (conoscopic) imaging in an optical microscope that has also been modified to allow selection of the illumination angles and polarization at the sample, and collected back focal plane images of silicon on silicon grating scatterometry targets with varying line widths. Using a slit illumination mask, the zero-order diffraction versus angle for -60° to +60° incident angles at a given polarization was obtained from a single image. By using reference images taken on a flat silicon background, we correct the raw target images for illumination source inhomogeneities and polarization-dependent transmission of the optics, and convert them to reflectance versus angle data for s-and p-polarizations, similar to that obtained from angle-resolved grating scatterometry. As with conventional scatterometry, the target lines need not be resolved for the reflectance signature to show sensitivity to small changes in the grating parameters. For a series of 300 nm pitch targets with line widths from 150 nm to 157 nm, we demonstrate nanometer-level sensitivity to line width with good repeatability, using 546 nm illumination. Additionally, we demonstrate a technique for separating the zero order from higher order diffraction on targets with multiple diffraction orders, allowing collection of both zero and higher order diffraction versus angle from the back focal plane image. As conventional images can be easily collected on the same microscope, the method provides a powerful tool for combining imaging metrology with scatterometry for optical critical dimension measurements in semiconductors.

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Section: The X-error Bars Shown Inmentioning

confidence: 99%