98 research outputs found
Improving the Resolution and Throughput of Achromatic Talbot Lithography
High-resolution patterning of periodic structures over large areas has
several applications in science and technology. One such method, based on the
long-known Talbot effect observed with diffraction gratings, is achromatic
Talbot lithography (ATL). This method offers many advantages over other
techniques, such as high resolution, large depth of focus, high throughput,
etc. Although the technique has been studied in the past, its limits have not
yet been explored. Increasing the efficiency and the resolution of the method
is essential and might enable many applications in science and technology. In
this work, we combine this technique with spatially coherent and
quasi-monochromatic light at extreme ultraviolet (EUV) wavelengths and explore
new mask design schemes in order to enhance its throughput and resolution. We
report on simulations of various mask designs in order to explore their
efficiency. Advanced and optimized nanofabrication techniques have to be
utilized to achieve high quality and efficient masks for ATL. Exposures using
coherent EUV radiation from the Swiss light source (SLS) have been performed,
pushing the resolution limits of the technique for dense hole or dot patterning
down to 40 nm pitch. In addition, through extensive simulations, alternative
mask designs with rings instead of holes are explored for the efficient
patterning of hole/dot arrays. We show that these rings exhibit similar aerial
images to hole arrays, while enabling higher efficiency and thereby increased
throughput for ATL exposures. The mask designs with rings show that they are
less prone to problems associated with pattern collapse during the
nanofabrication process and therefore are promising for achieving higher
resolution
Magnetic metamaterials in the blue range using aluminum nanostructures
We report an experimental and theoretical study of the optical properties of
two-dimensional arrays of aluminum nanoparticle in-tandem pairs. Plasmon
resonances and effective optical constants of these structures are investigated
and strong magnetic response as well as negative permeability are observed down
to 400 nm wavelength. Theoretical calculations based on the finite-difference
time-domain method are performed for various particle dimensions and lattice
parameters, and are found to be in good agreement with the experimental
results. The results show that metamaterials operating across the whole visible
wavelength range are feasible.Comment: 3 pages, 4 figure
Changes in the near edge X-ray absorption fine structure of hybrid organic-inorganic resists upon exposure
We report on the near edge X-ray absorption fine structure (NEXAFS)
spectroscopy of hybrid organic-inorganic resists. These materials are
nonchemically amplified systems based on Si, Zr, and Ti oxides, synthesized
from organically modified precursors and transition metal alkoxides by a
sol-gel route and designed for ultraviolet, extreme ultraviolet and electron
beam lithography. The experiments were conducted using a scanning transmission
X-ray microscope (STXM) which combines high spatial-resolution microscopy and
NEXAFS spectroscopy. The absorption spectra were collected in the proximity of
the carbon edge (~ 290 eV) before and after in situ exposure, enabling the
measurement of a significant photo-induced degradation of the organic group
(phenyl or methyl methacrylate, respectively), the degree of which depends on
the configuration of the ligand. Photo-induced degradation was more efficient
in the resist synthesized with pendant phenyl substituents than it was in the
case of systems based on bridging phenyl groups. The degradation of the methyl
methacrylate group was relatively efficient, with about half of the initial
ligands dissociated upon exposure. Our data reveal that the such dissociation
can produce different outcomes, depending on the structural configuration.
While all the organic groups were expected to detach and desorb from the resist
in their entirety, a sizeable amount of them remain and form undesired
byproducts such as alkene chains. In the framework of the materials synthesis
and engineering through specific building blocks, these results provide a
deeper insight into the photochemistry of resists, in particular for extreme
ultraviolet lithography
Extreme ultraviolet lithography reaches 5 nm resolution
Extreme ultraviolet (EUV) lithography is the leading lithography technique in
CMOS mass production, moving towards the sub-10 nm half-pitch (HP) regime with
the ongoing development of the next generation high-numerical aperture
(high-NA) EUV scanners. Hitherto, EUV interference lithography (EUV-IL)
utilizing transmission gratings has been a powerful patterning tool for the
early development of EUV resists and related processes, playing a key role in
exploring and pushing the boundaries of photon-based lithography. However,
achieving pattering with HPs well below 10 nm using this method presents
significant challenges. In response, our study introduces a novel EUV-IL setup
that employs mirror-based technology and circumvents the limitations of
diffraction efficiency towards the diffraction limit that is inherent in
conventional grating-based approaches. We present line/space patterning of HSQ
resist down to HP 5 nm using the standard EUV wavelength 13.5 nm, and the
compatibility of the tool with shorter wavelengths beyond EUV. The mirror-based
interference lithography tool paves the way towards the ultimate photon-based
resolution at EUV wavelengths and beyond. This advancement is vital for
scientific and industrial research, addressing the increasingly challenging
needs of nanoscience and technology and future technology nodes of CMOS
manufacturing in the few-nanometer HP regime
Lithographic performance of ZEP520A and mr-PosEBR resists exposed by electron beam and extreme ultraviolet lithography
Pattern transfer by deep anisotropic etch is a well-established technique for
fabrication of nanoscale devices and structures. For this technique to be
effective, the resist material plays a key role and must have high resolution,
reasonable sensitivity and high etch selectivity against the conventional
silicon substrate or underlayer film. In this work, the lithographic
performance of two high etch resistance materials was evaluated: ZEP520A
(Nippon Zeon Co.) and mr-PosEBR (micro resist technology GmbH). Both materials
are positive tone, polymer-based and non-chemically amplified resists. Two
exposure techniques were used: electron beam lithography (EBL) and extreme
ultraviolet (EUV) lithography. These resists were originally designed for EBL
patterning, where high quality patterning at sub-100 nm resolution was
previously demonstrated. In the scope of this work, we also aim to validate
their extendibility to EUV for high resolution and large area patterning. To
this purpose, the same EBL process conditions were employed at EUV. The figures
of merit, i.e. dose to clear, dose to size, and resolution, were extracted and
these results are discussed systematically. It was found that both materials
are very fast at EUV (dose to clear lower than 12 mJ/cm2) and are capable of
resolving dense lines/space arrays with a resolution of 25 nm half-pitch. The
quality of patterns was also very good and the sidewall roughness was below 6
nm. Interestingly, the general-purpose process used for EBL can be extended
straightforwardly to EUV lithography with comparable high quality and yield.
Our findings open new possibilities for lithographers who wish to devise novel
fabrication schemes exploiting EUV for fabrication of nanostructures by deep
etch pattern transfer.Comment: 20 pages, 4 figures, 3 table
Engineering Metal Adhesion Layers That Do Not Deteriorate Plasmon Resonances
Adhesion layers, required to stabilize metallic nanostngtures, dramatically deteriorate the performances of plasmonic sensors, by severely damping the plasmon modes. In this article, we show that these detrimental effects critically depend on the overlap of the electromagnetic near-field of the resonant plasmon mode with the adhesion layer and can be minimized by careful engineering of the latter. We study the dependence of the geometrical parameters such as layer thickness and shape on the near-field of localized plasmon resonances for traditional adhesion layers such as Cr, Ti, and h02. Our experiments and simulations reveal a strong dependence of the damping on the layer thickness, in agreement with the exponential decay of the piasmon near-field. We developed a method to minimize the damping by selective deposition of thin adhesion layers (<1 nm) In a manner that prevents the layer to overlap with the hotspots of the plasmonlc structure. Such a designed structure enables the use of standard Cr and Ti adhesion materials to fabricate robust plasmonic sensors without deteriorating their sensitivity
Squamotous-type sarcomatoid carcinoma of the lung with rhabdomyosarcomatous components
Lung carcinosarcoma is an infrequently biphasic tumor composed of carcinomatous and sarcomatous components. It is divided into endobronchial (squamous-type) and peripheral (glandular type) categories. The carcinomatous component is usually a squamous carcinoma, and the sarcomatous component usually resembles a fibrosarcoma or a malignant fibrous histiocytoma. The presence of rhabdomyoblastic differentiation in such neoplasms is exceedingly rare. There are strong associations with smoking and asbestosis. In this study, we describe a unique case of a 43-year-old man with a 75 packet/year smoking history in whom a rare mixed malignant tumor of the lung was diagnosed and treated by left pneumonectomy. Histological examination of the resected specimen showed squamous cell carcinoma and rhabdomyosarcoma components. Although rare, the association of a sarcomatoid carcinoma of the lung with squamous cell carcinoma and rhabdomyosarcomatous component is possible and should be kept in mind when dealing with these unusual tumors
Evaluation of lab-scale EUV microscopy using a table-top laser source
High brightness Extreme Ultraviolet (EUV) sources for laboratory operation are needed in nano-fabrication and actinic ("at-wavelength") inspection of the masks for high volume manufacturing in next generation lithography. Laser-plasma EUV sources have the required compactness and power scalability to achieve the demanding requirements. However, the incoherent emission lacks the brightness for single-shot high contrast imaging. On the other hand, fully coherent sources are considered to be unsuitable for full-field sample illumination and prone to speckles. We evaluate the capabilities of a lab-scale amplified-spontaneousemission (ASE) EUV laser source to combine brightness and high quality imaging with full-field imaging, along with rapid acquisition and compactness
Nanolithographic TopâDown Patterning of Polyoxovanadateâbased Nanostructures with Switchable Electrical Resistivity
The top-down fabrication of âŒ10â
nm vanadium oxide nanostructures by electron beam lithography based on a molecular vanadium oxide resist material is reported. The new material enables the large-scale deposition of electrically switchable nanostructures which can be directly incorporated in established e-beam lithography. The findings could in future enable the top-down fabrication of functional metal oxide nanostructures in the < 10â
nm domain.
The top-down lithographic fabrication of functional metal oxide nanostructures enables technologically important applications such as catalysis and electronics. Here, we report the use of molecular vanadium oxides, polyoxovanadates, as molecular precursors for electron beam lithography to obtain functional vanadium oxide nanostructures. The new resist class described gives access to nanostructures with minimum dimensions close to 10â
nm. The lithographically prepared structures exhibit temperature-dependent switching behaviour of their electrical resistivity. The work could lay the foundation for accessing functional vanadium oxide nanostructures in the sub-10-nm domain using industrially established nanolithographic methods
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