20 research outputs found
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
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
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
The Muon Portal Double Tracker for the Inspection of Travelling Containers
The Muon Portal Project has as its goal the design and construction of a real-size working detector prototype in scale 1:1, to inspect the content of travelling containers by means of the secondary cosmic-ray muon radiation and to recognize high-Z hidden materials (i.e. U, Pu). The tomographic image is obtained by reconstructing the input and output trajectories of each muon when it crosses the container and, consequently, the scattering angle, making use of two trackers placed above and below the container. The scan is performed without adding any external radiation, in a reasonable time (few minutes) and with a good spatial and angular resolution. The detector consists of 8 planes each segmented in 6 identical modules. Each module is made of scintillating strips with two WaveLength Shifting fibers (WLS) inside, coupled to Silicon photomultipliers. The customized read-out electronics employs programmable boards. Thanks to a smart read-out system, the number of output channels is reduced by a factor 10. The signals from the front-end modules are sent to the read-out boards, in order to convert analog signals to digital ones, by comparison with a threshold. The data are pre-analyzed and stored into a data acquisition PC. After an intense measurement and simulation campaign to carefully characterize the detector components, the first detection modules ( 1 Ă3 m2) have been already built. In this paper the detector architecture, particularly focusing on the used electronics and the main preliminary results will be presented. <P /
Effect of molecular weight on the EUV-printability of main chain scission type polymers
status: publishe