| POLYMERS Vol.60 No.3 |
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COVER STORY
Polymers Pushing the Limits of Semiconductors |
| COVER STORY: Highlight Reviews |
| Photoresists for Microlithography | Mitsuru UEDA |
| <Abstract> This
chapter describes photopolymers for microlithography, which have been
the workhorse in device manufacturing for several decades. The primary
focus is placed on resist materials that are responsible for lithographic
imaging. The topics covered in this chapter include the history, the
current status, and the future perspective of the resists. Furthermore,
innovations in the resist design and processing are also described. Keywords: Photoresist / Microlithography / Chemical Amplification Resist / KrF Resist / ArF Resist / Photoacid Generator / EUV Resist / UV Imprint / Block Copolymer Lithography |
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| Development of Extreme Ultraviolet Resist Materials | Hiroto KUDO and Tadatomi NISHIKUBO |
| <Abstract> The
development of high resolution patterns (less than 22nm line and spaces)
has been made by using an extreme ultraviolet (EUV) exposure system. To
achieve higher resolution pattern, several molecular resist materials
based on calixarene, low-molecular weight phenol resins, fullerene, and
ladder cyclic oligomer (noria) have been investigated using EUV exposure
system, and their resist patterns showed 22〜50 nm resolutions. Furthermore,
certain molecular glasses containing a photo-acid generator were examined
and showed 50 nm resolution. Although, these molecular glasses showed
high potential to give higher resolution patterns, their values of line-edge
roughness were not enough. The further examination of the synthesis of
new molecular glasses and EUV-exposure tools are under now consideration. Keywords: Electron Beam / Extreme Ultraviolet / Resist / Chemical Amplification / Molecular Resist / Roughness / Sensitivity / Resolution |
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| Directed Self-Assembly of Block Copolymers for Lithographic Applications | Hiroshi YOSHIDA |
| <Abstract> Demand
for ever smaller critical dimensions continues to push conventional photolithography
beyond the diffraction limit. Scientific and technological challenges arise as resolution requirements approach molecular length scales and the economics of new lithographic technologies become prohibitively expensive. Self-assembly has emerged as a way to overcome these limitations. In particular, block copolymer, which self-assembles a wide variety of periodic nano-domain structures, stands out as a promising alternative to produce features in the 10 nm scale. In this paper, methods such as graphoepitaxy and chemical registration, proposed to precisely control the self-assembly of block copolymers, are reviewed and their potential for lithographic application is discussed. Keywords: Block Copolymer / Directed Self-Assembly / Lithography / Graphoepitaxy / Chemical Registration |
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| UV Nanoimprint | Hiroshi HIROSHIMA |
| <Abstract> UV
nanoimprint, a method by which nanometer patterns are easily fabricated
at a low cost, is listed as a promising next generation lithography technology.
UV nanoimprint lithography is recently used as a tool for developing
next generation LSI processes which treat a few tens of nanometer patterns.
Despite of the fine patterning ability, UV nanoimprint lithography has
not been used in mass production of LSI circuits. One of the major problems
is unsufficient throughput in the filling of UV curable resin into mold
recesses. The process throughput is limited by the dissolution rate of
trapped gas in the UV curable resin. This situation can be dramatically
changed by using pentafluoropropane (PFP) as an imprinting ambient. Besides
the improvement of throughput, PFP has a favorable side effect that the
release force of a mold is reduced by one third. Though some drawback
(ex. enlargement of UV curable resin shrinkage) exists, UV nanoimprint
in PFP will be a standard process of UV nanoimprint in the near future. Keywords: UV Nanoimprint / Nanoimprint Lithography / Pentafluoropropane / Bubble Defect / Throughput |
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| COVER STORY:Topics and Products |
| Resist Materials for ArF Immersion Lithography | Koji NOZAKI |
| <Abstract> ArF
immersion lithography paved the way to realize the present state-of-the-art
semiconductor micro-fabrication technology for mass production of LSIs
of 45-nm technology node and beyond. Phase separation in a polymer blend
has been applying to give water repellent property for ArF immersion
resist materials. Keywords: Immersion Lithography / Resist / Phase Separation / Water Repellent |
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| Progress of Mask-Blanks and Nanoimprint Mold Development for Hard Disk Drive Application | Tsuyoshi WATANABE and Osamu NAGAREKAWA |
| <Abstract> Nanoimprint
technology has appeared in International Technology Roadmap for Semiconductors
(ITRS) in 1996 and is one of promising candidates for 22-nm half-pitch
or below at present. This technology is also available to fabricating
hard disk drive (HDD) media with an increased recording density. The fabrication
technology for HDD media is required five years earlier than that for
semiconductors. In this article, HOYA’s recent development and progress
of nanoimprint mold for HDD application is described. Keywords: Nanoimprint Mold / Photo-Mask Blanks / ITRS / Resist / HDD / DTM / BPM |
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| Fluorescent Resist Materials for Nanoimprint Lithography | Masaru NAKAGAWA |
| <Abstract> UV-curable
resins and thermoplastic polymers doped with a fluorescent dye were useful
for checking uniformity of residual layer thickness, detecting resist
pattern defect, and monitoring resin adhesion to a mold surface in nanoimprinting.
The facile and nondestructive inspection method by fluorescent microscopy
is described. Keywords: UV Nanoimprint Lithography / Thermal Nanoimprint Lithography / Fluorescent Resist / Pattern Inspection / Defect Detection / Residual Layer Thickness / Resin Adhesion / Fluorescent Microscopy |
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| Electron Beam Resists | Takumi UENO |
| <Abstract> Electron
beam resists have been widely used for photo-mask fabrication, since
the electron beam has an advantage in pattern fabrication capability.
To improve the sensitivity, the chemical amplification system has been
applied for the electron beam resists. Molecular resists combined with
chemical amplification have been also proposed for improvement in LER
(Line Edge Roughness) and resolution. Keywords: Main Chain Scission / Crosslinking / Chemical Amplification / Molecular Resists |
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| Recent Topics in Resist Development Used for Extreme Ultraviolet Lithography | Takahiro KOZAWA |
| <Abstract> The
development of extreme ultraviolet (EUV) lithography is steadily progressing
toward the insertion of 22 nm pilot lines in 2011. However, EUV lithography
has already demonstrated its resolution capability down to 11 nm. Considering
the nodes after 22 nm, LER is still a serious problem. The reduction
of LER requires continuous effort. Keywords: EUV Lithography / Resolution / Sensitivity / Line Edge Roughness |
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| Front-Line Polymer Science |
| Polymer Structure and Physical Properties at Non-Solvent Interfaces | Keiji TANAKA and Yoshihisa FUJII |
| <Abstract> Interfaces
of polymers with “non-solvents” play an important role in their functional
properties such as wettability, friction with lubricants, cell adhesion,
and biocompatibility. To design and construct highly functionalized polymers
for applications that exploit these characteristics, aggregation states
of the polymers at the liquid interfaces must be understood as the first
benchmark. However, this is experimentally difficult because such interfaces
are buried. In this review, we introduce recent development of the issue
with the advent of modern experimental techniques. Keywords: Liquid Interfaces / Molecular Motion / Aggregation Structure |
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