Using Aberration Test Patterns To Optimize The Performance Of Euv Aerial Imaging Microscopes
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Using Aberration Test Patterns To Optimize The Performance Of Euv Aerial Imaging Microscopes
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Author :
language : en
Publisher:
Release Date : 2009
Using Aberration Test Patterns To Optimize The Performance Of Euv Aerial Imaging Microscopes written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
The SEMATECH Berkeley Actinic Inspection Tool (AIT) is a prototype EUV-wavelength zoneplate microscope that provides high quality aerial image measurements of EUV reticles. To simplify and improve the alignment procedure we have created and tested arrays of aberration-sensitive patterns on EUV reticles and we have compared their images collected with the AIT to the expected shapes obtained by simulating the theoretical wavefront of the system. We obtained a consistent measure of coma and astigmatism in the center of the field of view using two different patterns, revealing a misalignment condition in the optics.
Japanese Journal Of Applied Physics
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Author :
language : en
Publisher:
Release Date : 2007
Japanese Journal Of Applied Physics written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with Physics categories.
Annual Symposium On Photomask Technology
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Author :
language : en
Publisher:
Release Date : 2002
Annual Symposium On Photomask Technology written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with Integrated circuits categories.
Physics Briefs
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Author :
language : en
Publisher:
Release Date : 1988
Physics Briefs written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1988 with Physics categories.
Improving The Performance Of The Actinic Inspection Tool With An Optimized Alignment Procedure
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Author :
language : en
Publisher:
Release Date : 2009
Improving The Performance Of The Actinic Inspection Tool With An Optimized Alignment Procedure written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
Extreme ultraviolet (EUV) microscopy is an important tool for the investigation of the performance of EUV masks, for detecting the presence and the characteristics of defects, and for evaluating the effectiveness of defect repair techniques. Aerial image measurement bypasses the difficulties inherent to photoresist imaging and enables high data collection speed and flexibility. It provides reliable and quick feedback for the development of masks and lithography system modeling methods. We operate the SEMATECH Berkeley Actinic Inspection Tool (AIT), a EUV microscope installed at the Advanced Light Source at Lawrence Berkeley National Laboratory. The AIT is equipped with several high-magnification Fresnel zoneplate lenses, with various numerical aperture values, that enable it image the reflective mask surface with various resolution and magnification settings. Although the AIT has undergone significant recent improvements in terms of imaging resolution and illumination uniformity, there is still room for improvement. In the AIT, an off-axis zoneplate lens collects the light coming from the sample and an image of the sample is projected onto an EUV-sensitive CCD camera. The simplicity of the optical system is particularly helpful considering that the AIT alignment has to be performed every time that a sample or a zoneplate is replaced. The alignment is sensitive to several parameters such as the lens position and orientation, the illumination direction and the sample characteristics. Since the AIT works in high vacuum, there is no direct access to the optics or to the sample during the alignment and the measurements. For all these reasons the alignment procedures and feedback can be complex, and in some cases can reduce the overall data throughput of the system. In this paper we review the main strategies and procedures that have been developed for quick and reliable alignments, and we describe the performance improvements we have achieved, in terms of aberration magnitude reduction.
Aerial Image Microscopes For The Inspection Of Defects In Euv Masks
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Author :
language : en
Publisher:
Release Date : 2002
Aerial Image Microscopes For The Inspection Of Defects In Euv Masks written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with categories.
The high volume inspection equipment currently available to support development of EUV blanks is non-actinic. The same is anticipated for patterned EUV mask inspection. Once potential defects are identified and located by such non-actinic inspection techniques, it is essential to have instrumentation to perform detailed characterization, and if repairs are performed, re-evaluation. The ultimate metric for the acceptance or rejection of a mask due to a defect, is the wafer level impact. Thus measuring the aerial image for the site under question is required. An EUV Aerial Image Microscope (''AIM'') similar to the current AIM tools for 248nm and 193nm exposure wavelength is the natural solution for this task. Due to the complicated manufacturing process of EUV blanks, AIM measurements might also be beneficial to accurately assessing the severity of a blank defect. This is an additional application for an EUV AIM as compared to today's use In recognition of the critical role of an EUV AIM for the successful implementation of EUV blank and mask supply, International SEMATECH initiated this design study with the purpose to define the technical requirements for accurately simulating EUV scanner performance, demonstrating the feasibility to meet these requirements and to explore various technical approaches to building an EUV AIM tool.
Photon Flux Requirements For Euv Reticle Imaging Microscopy In The 22 And 16 Nm Nodes
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Author :
language : en
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Release Date : 2010
Photon Flux Requirements For Euv Reticle Imaging Microscopy In The 22 And 16 Nm Nodes written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
EUV-wavelength actinic microscopy yields detailed information about EUV mask patterns, architectures, defects, and the performance of defect repair strategies, without the complications of photoresist imaging. The measured aerial image intensity profiles provide valuable feedback to improve mask and lithography system modeling methods. In order to understand the photon-flux-dependent pattern measurement limits of EUV mask-imaging microscopy, we have investigated the effects of shot noise on aerial image linewidth measurements for lines in the 22 and 16-nm generations. Using a simple model of image formation near the resolution limit, we probe the influence of photon shot noise on the measured, apparent line roughness. With this methodology, we arrive at general flux density requirements independent of the specific EUV microscope configurations. Analytical and statistical analysis of aerial image simulations in the 22 and 16-nm generations reveal the trade-offs between photon energy density (controllable with exposure time), effective pixel dimension on the CCO (controlled by the microscope's magnification ratio), and image log slope (ILS). We find that shot-noise-induced linewidth roughness (LWR) varies imersely with the square root of the photon energy density, and is proportional to the imaging magnification ratio. While high magnification is necessary for adequate spatial resolution, for a given flux density, higher magnification ratios have diminishing benefits. With practical imaging parameters, we find that in order to achieve an LWR (3[sigma]) value of 5% of linewidth for dense, 88-nm mask features with 80% aerial image contrast and 13.5-nm effective pixel width (1000x magnification ratio), a peak photon flux of approximately 1400 photons per pixel per exposure is required.
Image Based Extreme Ultraviolet Lithography
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Author : Germain L. Fenger
language : en
Publisher:
Release Date : 2013
Image Based Extreme Ultraviolet Lithography written by Germain L. Fenger and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Imaging systems categories.
"A significant factor in the degradation of nanolithographic image fidelity is optical wavefront aberrations on aerial image become more influential. The tolerance of such aberrations is governed by the requirements of features that are being imaged, often requiring lenses that can be corrected with a high degree of accuracy and precision. Resolution of lithographic systems is driven by scaling wavelength down and numerical aperture (NA) up. However, aberrations are also affected from the changes in wavelength and NA. Reduction in wavelength or increase in NA result in greater impact of aberrations, where the latter shows a quadratic dependence. Current demands in semiconductor manufacturing are constantly pushing lithographic systems to operate at the diffraction limit; hence, prompting a need to reduce all degrading effects on image properties to achieve maximum performance. Therefore, the need for highly accurate in-situ aberration measurement and correction is paramount. In this work, an approach has been developed in which several targets including phase wheel, phase disk, phase edges, and binary structures are used to generate optical images to detect and monitor aberrations in extreme ultraviolet (EUV) lithographic systems. The benefit of using printed patterns as opposed to other techniques is that the lithography system is tested under standard operating conditions. Mathematical models in conjunction with iterative lithographic simulations are used to determine pupil phase wavefront errors and describe them as combinations of Zernike polynomials."--Abstract.
Euv Pattern Defect Detection Sensitivity Based On Aerial Image Linewidth Measurements
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Author :
language : en
Publisher:
Release Date : 2010
Euv Pattern Defect Detection Sensitivity Based On Aerial Image Linewidth Measurements written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
As the quality of EUV-wavelength mask inspection microscopes improves over time, the image properties and intensity profiles of reflected light can be evaluated in ever-greater detail. The SEMATECH Berkeley Actinic Inspection Tool (AIT) is one such microscope, featuring mask resolution values that match or exceed those available through lithographic printing in current photoresists. In order to evaluate the defect detection sensitivity of the AIT for dense line patterns on typical masks, the authors study the line width roughness (LWR) on two masks, as measured in the EUV images. They report the through-focus and pitch dependence of contrast, image log slope, linewidth, and LWR. The AIT currently reaches LWR 3[sigma] values close to 9 nm for 175 nm half-pitch lines. This value is below 10% linewidth for nearly all lines routinely measured in the AIT. Evidence suggests that this lower level may arise from the mask's inherent pattern roughness. While the sensitivity limit of the AlT has not yet been established, it is clear that the AIT has the required sensitivity to detect defects that cause 10% linewidth changes in line sizes of 125 nm and larger.
Optical Modeling Of Fresnel Zoneplate Microscopes
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Author :
language : en
Publisher:
Release Date : 2011
Optical Modeling Of Fresnel Zoneplate Microscopes written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Defect free masks remain one of the most significant challenges facing the commercialization of extreme ultraviolet (EUV) lithography. Progress on this front requires high-performance wavelength-specific metrology of EUV masks, including high-resolution and aerial-image microscopy performed near the 13.5 nm wavelength. Arguably the most cost-effective and rapid path to proliferating this capability is through the development of Fresnel zoneplate-based microscopes. Given the relative obscurity of such systems, however, modeling tools are not necessarily optimized to deal with them and their imaging properties are poorly understood. Here we present a modeling methodology to analyze zoneplate microscopes based on commercially available optical modeling software and use the technique to investigate the imaging performance of an off-axis EUV microscope design. The modeling predicts that superior performance can be achieved by tilting the zoneplate, making it perpendicular to the chief ray at the center of the field, while designing the zoneplate to explicitly work in that tilted plane. Although the examples presented here are in the realm of EUV mask inspection, the methods described and analysis results are broadly applicable to zoneplate microscopes in general, including full-field soft-x-ray microscopes rou tinely used in the synchrotron community.