Topic
Contrast transfer function
About: Contrast transfer function is a research topic. Over the lifetime, 934 publications have been published within this topic receiving 26533 citations.
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TL;DR: The classical spherical aberration structural coefficient for a plano-convex lens is compared to one derived via Fourier optics in this paper, and the effects of these differences on diffraction are then studied in the maximum Strehl planes.
Abstract: The classical spherical aberration structural coefficient for a plano-convex lens is compared to one derived via Fourier optics. The effects of these differences on diffraction are then studied in the maximum Strehl planes.
5 citations
06 May 2005
TL;DR: In this article, resist-based measurements of the contrast transfer function for the 0.3-NA MET optic were performed for both bright-field and dark-field mask patterns, and the orientation dependence of the CTF was measured in order to evaluate the effect of nonrotationally symmetric lens aberrations.
Abstract: Although extreme ultraviolet (EUV) lithography offers the possibility of very high-resolution patterning, the projection optics must be of extremely high quality in order to meet this potential. One key metric of the projection optic quality is the contrast transfer function (CTF), which is a measure of the aerial image contrast as a function of pitch. A static microfield exposure tool based on the 0.3-NA MET optic and operating at a wavelength of 13.5 nm has been installed at the Advanced Light Source, a synchrotron facility at the Lawrence Berkeley National Laboratory. This tool provides a platform for a wide variety of research into EUV lithography. In this work we present resist-based measurements of the contrast transfer function for the MET optic. These measurements are based upon line/space patterns printed in several different EUV photoresists. The experimental results are compared with the CTF in aerial-image simulations using the aberrations measured in the projection optic using interferometry. In addition, the CTF measurements are conducted for both bright-field and dark-field mask patterns. Finally, the orientation dependence of the CTF is measured in order to evaluate the effect of non-rotationally symmetric lens aberrations. These measurements provide valuable information in interpreting the results of other experiments performed using the MET and similar systems.
5 citations
Journal Article•
TL;DR: In this paper, the theoretical basis of defocus-modulation image processing (DMIP) for correcting spherical aberration in transmission electron microscopy is clarified, and a novel approach of practical use for verification of the just-focus position and aberration function by DMIP is also proposed.
5 citations
TL;DR: A design for a low- voltage scanning electron microscope with the low-voltage foil corrector is presented and a fully electrostatic column has been designed and characterised by using aberration integrals and ray tracing calculations.
5 citations
TL;DR: There is a relationship between the phase shift and defocus that allows us to find a series of 'alignment-free' focal conditions and a triangular relation among C(s), defocus and lattice spacing is established for proper image contrast and 'aligned' imaging with the C(S) corrected microscope.
Abstract: For spherical aberration corrected transmission electron microscopes recently developed, the Scherzer resolution in proportion to C(s) 1/4 lambda 3/4 is still inevitably limited by the influence of some other electron optical factors, such as chromatic aberration coefficient of objective lens (C(c)), beam divergence and alignment, incident electron energy spread (deltaE), and the instability of accelerating voltage (deltaV) and of lens current (deltaI). Depending on the image resolution guaranteed by C(s) correction, the defocus spread caused by C(c), deltaV, deltaI and deltaE would need to be reduced. The effect of beam alignment as a phase shift in contrast transfer function is also studied for the C(s) corrected microscopes with different values of C(s), defocus and spatial frequency. There is a relationship between the phase shift and defocus that allows us to find a series of 'alignment-free' focal conditions. A triangular relation among C(s), defocus and lattice spacing is established for proper image contrast and 'alignment-free' imaging with the C(s) corrected microscope.
5 citations