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Introduction
The history of information technology has been a
history of miniaturization of the ‘bits’, i.e. a
tendency towards supplying data storage systems based on
ultrahigh-density information carriers with long-term stability,
this storage capacity having become equivalent to the
information in large libraries. Optical data storage is very
convenient for use due to storage media being removable.
Readonly memory (ROM) is a read-only optical data storage
medium, where the data are recorded during the manufacture of
the disks. ROM systems detect the stored data by sensing changes
in the intensity or polarization of a reflected laser beam as
the focused spot scans along a data track. In the form of the
compact disk (CD), this optical data storage medium is used
widely for music distribution and for computer software
(CD-ROM). In this case the data readout procedure retrieves data
by sensing changes in reflectivity of the patterned, metallized
film deposited on a plastic substrate. The digital video disk
(DVD) standard offers higher area density per layer, and as many
as four layers of recorded information with sufficient read-out
bandwidth and capacity for distribution
of several hours’worth of high-quality compressed video.
X-ROM Promise
We propose Ultrahigh-density
x-ray optical memory, dubbed X-ROM, as a promising new
technology for storing terabyte-scale digital information with
revolutionary ultra-fast readout speed.
Why X-Rays?
Contemporary information
nanotechnological processes require non-destructive methods for
sample characterization.
The X-ROM is an ultrahigh-density information carrier with
long-term stability because the x-ray diffraction methods are
non-destructive compared with other local probing approaches
such as transmission electron microscopy (TEM), scanning
electron microscopy (SEM) and more recently scanning tunnelling
microscopy (STM) and atomic force microscopy (AFM). The
application of these imaging techniques with atomic resolution
has become a standard in the most advanced laboratories.
However, every technique has its limitations: for example SEM, AFM and STM can only
be used to visualize surfaces, while the analysis with the TEM
is destructive and requires very thin samples and complex
preparation procedures. Moreover, all microscopy techniques
involving electrons or other charged particles for sample
probing need vacuum conditions. These limitations are usually
not encountered with x-rays (and in particular
‘hard’ x-rays, i.e. with energies from a few keV to
few tens of keV), which can penetrate deeply into condensed
matter and are not absorbed in air, permitting one to
investigate the sample in its natural environment at atmospheric
pressure. Different x-ray
scattering and diffraction techniques can provide complementary
information about the internal structure of materials and the
shape, size, deformation and composition of quantum structures. With the development of scattering
theory for rough interfaces in multilayers, the grazing-angle
x-ray scattering method has become a powerful non-destructive
technique for probing buried interface structures with atomic
resolution. The silicon high-quality crystalline layers and SiGe
alloys are promising materials for realizing quantum dot
structures for x-ray terabyte storage applications, since they
can readily be implemented within existing Si technology. In the
general case the procedure of digital data read-out from the
X-ROM can be performed by using the principles of x-ray optics,
as well as on the basis of the principles of x-ray diffraction
optics.
Technology
We have developed a new
data read-out nanotechnology based on the grazing-angle
incidence x-ray backscattering diffraction (GIXB) technique,
which is used under conditions of specular vacuum wave
suppression.
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Prospects
As you have seen from the paragraphs above, X-ROM is a new,
promising technology the implications of which are far reaching.
Our Research & Development team is finalizing the
production-feasible implementation of the proposed X-ray Optical
Data Storage Device.
As we are a newly established organization, we are currently
seeking colaboration and partnership with the
well-established companies in IT and High Tech. Industries.
If you are representing a company or
organization interested in joint projects and
collaboration, or simply an entrepreneur willing
to join this project aiming at delivering the
X-ROM technology to the Hight Tech. market, you have
several options to send your proposal and/or formal
collaboration request via the contact information listed on our
Contact Us
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Maskless
Zone-Plate-Array Lithography (ZPAL) Technique
In the figure above is shown the data recording
scheme, in which the maskless zone-plate-array lithography
(ZPAL) technique is applied. ZPAL uses: a narrow bandwidth
source, an array of diffractive lenses (e.g., Fresnel zone
plates) that focuses an array of on-axis spots on the surface of
a wafer coated with photosensitivematerial (photoresist) and a
scanning stage for printing arbitrary patterns within a
photoresist without a mask. The recorded pattern is
developed and fixed. Depending on the nature of the photoresist,
the illuminated areas are removed (positive resist) or conserved
(negative resist). As a result, the desired pattern is converted
into a variation of the photoresist’s profile height. This
profile is transferred into the wafer after the chemical
etching.
For further information on this subject please
refer to:
Two-dimensional
ultrahigh-density x-ray optical memory
Proposed two-dimensional ultrahigh-density x-ray
optical memory, named X-ROM, is a semiconductor wafer, in which
the high-reflectivity nanosized x-ray mirrors are embedded. Data
are encoded due to certain positions of the mirrors. A new
scheme of data read-out procedure from nanostructured X-ROM
based on the glancing-angle incidence x-ray (GIX) technique is
presented in figure, where and are the
wave-vectors of incident plane x-ray wave and specular wave
reflected from the X-ROM respectively. The angle of
incidence of the x-rays is satisfying the condition
of total external reflection for the sub-surface nanosized
domains only.
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