Published by De Gruyter

Volume 4 Issue 4 - Optical Lithography / Guest Editors: Andreas Erdmann and Masato Shibuya

Issue of Advanced Optical Technologies

Contents
Journal Overview

Publicly Available August 4, 2015

Cover and Frontmatter

Page range: i-iii

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Views

Publicly Available August 4, 2015

ITRS lithography roadmap: 2015 challenges

Mark Neisser, Stefan Wurm

Page range: 235-240

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Abstract

In the past few years, novel methods of patterning have made considerable progress. In 2011, extreme ultraviolet (EUV) lithography was the front runner to succeed optical lithography. However, although EUV tools for pilot production capability have been installed, its high volume manufacturing (HVM) readiness continues to be gated by productivity and availability improvements taking longer than expected. In the same time frame, alternative and/or complementary technologies to EUV have made progress. Directed self-assembly (DSA) has demonstrated improved defectivity and progress in integration with design and pattern process flows. Nanoimprint improved performance considerably and is pilot production capable for memory products. Maskless lithography has made progress in tool development and could have an α tool ready in the late 2015 or early 2016. But they all have to compete with multiple patterning. Quadruple patterning is already demonstrated and can pattern lines and spaces down to close to 10-nm half pitch. The other techniques have to do something better than quadruple patterning does to be chosen for implementation. DSA and NIL promise a lower cost. EUV promises a simpler and shorter process and the creation of 2-D patterns more easily with much reduced complexity compared to multiple patterning. Maskless lithography promises to make chip personalization easy and to be particularly cost effective for low-volume chip designs. Decision dates for all of the technologies are this year or next year.

Community

Publicly Available July 24, 2015

EOS NEWS: Report from the World of Photonics Congress 2015

Jyrki Saarinen

Page range: 241-242

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Publicly Available July 24, 2015

Conference Notes

Page range: 243-245

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Publicly Available July 21, 2015

Conference Calendar

Page range: 247-249

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Topical Issue: Optical Lithography

Editorial

Publicly Available July 23, 2015

Introduction to the special issue on optical lithography

Andreas Erdmann, Masato Shibuya

Page range: 251-252

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Review Articles

May 20, 2015

How to make lithography patterns print: the role of OPC and pattern layout

Peter De Bisschop

Page range: 253-284

Abstract

This paper will review some of the methods that have been devised to bring lithography-generated patterns as close to the desired target patterns as possible, while making them also robust against inevitable deviations from the ideal conditions during the printing process. Optical proximity correction (OPC) is the first step in this process. Various ways have been developed for efficient creation of accurate process window aware OPC models. Also, the use of the actual OPC step, to transform the target patterns into actual lithography mask patterns has seen significant progress. A computational verification step then checks whether the predicted pattern shapes meet the quality requirements and identifies any residual failures or weak patterns (‘hotspots’). Once the mask is available, a second verification step, now looking at patterns on printed wafers, is performed to make sure that all critical patterns print to within the requested tolerances. Each of the steps in this flow can – and usually does – lead to corrective iterations to one of the previous steps. As the task of ensuring sufficient process margin is gradually becoming more difficult, with the ever decreasing pattern sizes, constraints are being increasingly defined on the type of patterns that can be allowed in the target layout itself (design restrictions), leading to a tendency toward more regular designs, an evolution that needs to be facilitated by the patterning technology and materials used. So the problem of ensuring good printability now also involves both layout and technology, and we will look into this aspect of the optimization problem as well.

July 3, 2015

Exposure tool control for advanced semiconductor lithography

Tomoyuki Matsuyama

Page range: 285-296

Abstract

This is a review paper to show how we control exposure tool parameters in order to satisfy patterning performance and productivity requirements for advanced semiconductor lithography. In this paper, we will discuss how we control illumination source shape to satisfy required imaging performance, heat-induced lens aberration during exposure to minimize the aberration impact on imaging, dose and focus control to realize uniform patterning performance across the wafer and patterning position of circuit patterns on different layers. The contents are mainly about current Nikon immersion exposure tools.

Publicly Available July 30, 2015

Performance of 100-W HVM LPP-EUV source

Hakaru Mizoguchi, Hiroaki Nakarai, Tamotsu Abe, Krzysztof M. Nowak, Yasufumi Kawasuji, Hiroshi Tanaka, Yukio Watanabe, Tsukasa Hori, Takeshi Kodama, Yutaka Shiraishi, Tatsuya Yanagida, Georg Soumagne, Tsuyoshi Yamada, Taku Yamazaki, Shinji Okazaki, Takashi Saitou

Page range: 297-309

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Abstract

At Gigaphoton Inc., we have developed unique and original technologies for a carbon dioxide laser-produced tin plasma extreme ultraviolet (CO 2 -Sn-LPP EUV) light source, which is the most promising solution for high-power high-volume manufacturing (HVM) EUV lithography at 13.5 nm. Our unique technologies include the combination of a pulsed CO 2 laser with Sn droplets, the application of dual-wavelength laser pulses for Sn droplet conditioning, and subsequent EUV generation and magnetic field mitigation. Theoretical and experimental data have clearly shown the advantage of our proposed strategy. Currently, we are developing the first HVM light source, ‘GL200E’. This HVM light source will provide 250-W EUV power based on a 20-kW level pulsed CO 2 laser. The preparation of a high average-power CO 2 laser (more than 20 kW output power) has been completed in cooperation with Mitsubishi Electric Corporation. Recently, we achieved 140 W at 50 kHz and 50% duty cycle operation as well as 2 h of operation at 100 W of power level. Further improvements are ongoing. We will report the latest status and the challenge to reach stable system operation of more than 100 W at about 4% conversion efficiency with 20-μm droplets and magnetic mitigation.

July 8, 2015

Resist material options for extreme ultraviolet lithography

Takahiro Kozawa

Page range: 311-317

Abstract

Owing to the worldwide efforts, the development of extreme ultraviolet (EUV) lithography has significantly progressed during the past decade. The resolution of chemically amplified resists has reached sub-16-nm region. From the viewpoint of the extendibility of EUV lithography, the development of resist materials capable of resolving sub-10-nm is an urgent task. In this review, the resist material options for EUV lithography are discussed on the basis of the EUV sensitization mechanisms after reviewing the problems for the sub-10-nm fabrication.

July 1, 2015

Development of element technologies for EUVL

Hiroo Kinoshita, Takeo Watanabe, Tetsuo Harada

Page range: 319-331

Abstract

Thirty years have passed since the first report on extreme ultraviolet lithography (EUVL) was presented at the annual meeting of the Japanese Society of Applied Physics in 1986. This technology is now in the manufacturing development stage. The high-volume manufacturing of dynamic-random-access-memory (DRAM) chips with a line width of 15 nm is expected in 2016. However, there are critical development issues that remain: generating a stand-alone EUV source with a higher power and producing a mask inspection tool for obtaining zero-defect masks. The Center for EUVL at the University of Hyogo was established in 2010. At present, it utilizes various types of equipment, such as an EUV mask defect inspection tool, an interference-lithography system, a device for measuring the thickness of carbon contamination film deposited by resist outgassing, and reflectivity measurement systems.

Research Articles

June 16, 2015

Focus tolerance influenced by source size in Talbot lithography

Takashi Sato, Akiko Yamada, Takeshi Suto

Page range: 333-338

Abstract

Using a simulation, we investigate the effects of the light source size and derive an effective method for suppression of the subfringes that appear in ArF Talbot lithography, which has been proposed for submicron pattern transfer applications. The appearance of the subfringes, which were caused by interference, was related to the size of the light source. If an appropriate light source size is chosen, then, a large process window can be obtained. Guidelines for source size selection are given.

June 4, 2015

Flat-field anastigmatic mirror objective for high-magnification extreme ultraviolet microscopy

Mitsunori Toyoda

Page range: 339-346

Abstract

To apply high-definition microscopy to the extreme ultraviolet (EUV) region in practice, i.e. to enable in situ observation of living tissue and the at-wavelength inspection of lithography masks, we constructed a novel reflective objective made of three multilayer mirrors. This objective is configured as a two-stage imaging system made of a Schwarzschild two-mirror system as the primary objective and an additional magnifier with a single curved mirror. This two-stage configuration can provide a high magnification of 1500, which is suitable for real-time observation with an EUV charge coupled device (CCD) camera. Besides, since off-axis aberrations can be corrected by the magnifier, which provides field flattener optics, we are able to configure the objective as a flat-field anastigmatic system, in which we will have a diffraction-limited spatial resolution over a large field-of-view. This paper describes in detail the optical design of the present objective. After calculating the closed-form equations representing the third-order aberrations of the objective, we apply these equations to practical design examples with a numerical aperture of 0.25 and an operation wavelength of 13.5 nm. We also confirm the imaging performances of this novel design by using the numerical ray-tracing method.

About this journal

Objective

Advanced Optical Technologies is a strictly peer-reviewed scientific journal. The major aim of Advanced Optical Technologies is to publish recent progress in the fields of optical design, optical engineering, and optical manufacturing. Advanced Optical Technologies has a main focus on applied research and addresses scientists as well as experts in industrial research and development.

Advanced Optical Technologies partners with the European Optical Society (EOS). All its 4.500+ members have free online access to the journal through their EOS member account.

Topics

Optical design
Lithography
Opto-mechanical engineering
Illumination and lighting technology
Precision fabrication
Image sensor devices
Optical materials (polymer based, inorganic, crystalline/amorphous)
Optical instruments in life science (biology, medicine, laboratories)
Optical metrology
Optics in aerospace/defense
Simulation, interdisciplinary
Optics for astronomy
Standards
Consumer optics
Optical coatings

Article formats
Tutorial, Review Article, Research Article, Letter, Short Communication, Views

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