1. Two-layer ultra-high density x-ray optical memory (X-ROM)
In a glance:
presenting author:
Dr. Hakob P. Bezirganyan,
X-ROM, Inc.
co-authors:
Siranush E. Bezirganyan,
Hayk H. Bezirganyan (Jr.),
Petros H. Bezirganyan (Jr.).
Optical system of typical drive.
DVD Innovations.
What’s next ?
X-ray optical memory.
Zone-plate-array lithography.
X-ROM characteristic function.
Our answer to the question above.
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

2. Copyright © 2006 X-ROM, Inc. All rights reserved.
Main References
Bezirganyan H.P., Bezirganyan P.H., Phys. Stat. Sol. (a), 1988, 105,
Bezirganyan H.P., Phys. Stat. Sol. (a), 1988, 109,
Bezirganyan H.P., Bezirganyan H.H. (Jr.), Bezirganyan S.E., Bezirganyan P.H. (Jr.), Opt. Commun., 2004, 238/(1-3),
Bezirganyan H.P., Bezirganyan H.H. (Jr.), Bezirganyan S.E., Bezirganyan P.H. (Jr.), Mossikyan Y.G., J. Opt. A: Pure Appl. Opt., 2005, 7/10,
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

3. 20th Century: The Compact Disc
Patented in 1970 by James T. Russell as a means for durable audio data storage.
Mass production starts in 1985 by Philips and Sony.
Data Density: ~ 1Mbyte/mm2
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

4. Optical system of typical drive
Conventional optical storage uses a focused laser beam to access individual bits in a single layer. Optical head reads the information by capturing reflected light as the laser beam travels across the pits and lands.
Changes in light intensity are interpreted as 0’s and 1’s.
Pits can be either dark on bright background or reversed.
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

5. Improvements of CD → to DVD (pit dimensions etc.)
Innovations:
Dual layer
Increased numerical aperture
Decreased depth of focus
Improved signal to noise
Data Density: ~7 MByte/mm2
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

6. Numerical Aperture (NA)
The diameter of the diffraction limited spot is directly proportional to the laser wavelength and inversely proportional to the numerical aperture (NA) of the imaging lens.
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

7. Solid-Immersion Lens (SIL)
A solid-immersion lens (SIL) can increase the effective Numerical Aperture, which, consequently, gives the possibility to increase the density of data carrier elements. However, this requires an evanescent coupling between the SIL and disk.
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

8. Copyright © 2006 X-ROM, Inc. All rights reserved.
Comparison Table
Feature
DVD CD
Substrate Dia./Thick.
120 x 1.2 mm
Sides
1 or 2 1
Layers per side
Capacity (GB)
4.7, 8.54, 9.4, 17
0.7
Track Pitch (micron)
0.74
1.6
Minimal pit length (micron)
0.44
0.83
Linear scan velocity
3.6 m/s
1.3 m/s
Laser wavelength
635 nm
780 nm
Numerical Aperture
0.6
0.45
Spot Size
1058 nm
1733 nm
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

9. Copyright © 2006 X-ROM, Inc. All rights reserved.
What’s next ?
0.7 GB
9 GB
50 ~ 100 GB ? ?
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

10. An example of the ultrahigh density digital data carrier
Most important aspect of nanotechnology applications in the information ultrahigh storage is the miniaturization of data carrier elements of the storage media with emphasis on the long-term stability.
An example: Let the single-bit linear size Lbit = 10 nm and the bit spacing Δlbit = 10 nm, then a memory capacity of the ultrahigh storage material with surface area S = 1 cm2 is equal to:
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

11. An example of the ultrahigh density digital data carrier
In considered example, an ultrahigh density two-sided digital data storage carrier with two layers per each side and 12 cm of edge size of the square shaped substrate has following capacity:
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

12. Copyright © 2006 X-ROM, Inc. All rights reserved.
Data recording nanotechnology based on Zone-plate-array lithography (ZPAL)
ZPAL
is developed by Massachusetts Institute of Technology, USA.
ZPAL uses:
a narrow bandwidth source,
an array of diffractive lenses (e.g., Fresnel zone plates) focuses an array of on-axis spots on the surface of a wafer coated with photosensitive material (photoresist),
a scanning stage, to print arbitrary patterns within a photoresist without a mask.
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

13. Copyright © 2006 X-ROM, Inc. All rights reserved.
Digital data read-out procedure using the glancing-angle incidence x-rays
X-rays reflection from the proposed X-ROM, takes place either by the GIXB in first silicon layer or the difference in refractive indexes of the second silicon layer and of embedded germanium domains.
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

14. X-ROM Characteristic Function
A characteristic function ΔR = (R2 – R) is introduced for the proposed X-ROM,
where:
R2 is the reflectivity coefficient of the x-ray plane wave reflected from or diffracted by the X-ROM wafer.
R is the reflectivity coefficient of the x-ray plane wave reflected from the nanosized mirror material.
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

15. X-ROM Characteristic Function
The minimum values of X-ROM characteristic function are most appropriate for the proposed digital data read-out procedure.
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

16. Our point of view on what could be next:
9 GB
50 ~ 100 GB GB
X-ROM
two-layer
two-sided
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.

17. Copyright © 2006 X-ROM, Inc. All rights reserved.
Thank you
We hope that you’ve enjoyed this presentation, and that we were able to answer some of your questions about the X-ROM Technology, and convey the potential and the impact this new technology can have on the future of data storage.
Sincerely,
X-ROM R & D Team
X-ROM Technology
Copyright © 2006 X-ROM, Inc. All rights reserved.