Data storage device and method of production therefor

Abstract

The present invention relates to a data storage device comprising: a data storage medium for storing data in the form of topographic features; and at least one probe for writing and / or reading the data stored in the data storage medium, wherein the data storage medium is formed on a support layer, the support layer having a lower shear modulus than the data storage medium

Description

FIELD OF THE INVENTION[0001]The present invention relates to a data storage device and particularly to a data storage device such as a thermomechanical probe storage device. The present invention also extends to a method of producing such a data storage device.BACKGROUND OF THE INVENTION[0002]A data storage device based on the atomic force microscope (AFM) is disclosed in “The millipede—more than 1,000 tips for future AFM data storage” by P. Vettiger et al., IBM Journal Research Development, Vol. 44, No. 3, March 2000. The storage device has a read and write function based on a mechanical x-, y-scanning of a storage medium with an array of probes each having a tip. The probes operate in parallel with each probe scanning, during operation, an associated field of the storage medium. The storage medium comprises a polymethylmethacrylate (PMMA) layer. The tips, which each have a diameter of between 5 nm to 40 nm, are moved across the surface of the polymer layer in a contact mode. The c...

AI Technical Summary

Benefits of technology

[0008]According to an embodiment of a first aspect of the present invention, there is provided a data storage device comprising: a data storage medium for storing data in the form of topographic features; and at least one probe for writing and / or reading the data stored in the data storage medium, wherein the data storage medium is formed on a support layer, the support layer having a lower shear modulus than the data storage medium. The mechanical stress field that is created in the data storage medium where an indentation mark is written thereon by way of a tip is absorbed by the support layer by virtue of the latter having a lower shear modulus than the data storage medium. Accordingly, since the back-action of the mechanical stress field is, in this case, reduced, rim formation around an opening of an indentation mark is reduced compared to what is obtained with previously-proposed data storage devices.

[0009]Preferably, the data storage medium comprises a layer of poly-aryletherketone, PAEK. PAEK is a polymer that demonstrates stability when exposed to elevated temperatures such as, for example, those used to heat a tip for writing data thereon. PAEK has a shear modulus of about 3 to 5 GPa.

[0010]Desirably, the shear modulus of the support layer is <1 GPa. By using a support layer that has a shear modulus that is <1 GPa, the mechanical stress field that is created in and around the region of the data storage medium that is contacted by a tip when data is written thereon, is transmitted and spread in the support layer in a direction parallel to the surface of the data storage medium over a region that is much wider than the tip diameter. Thus, the back-action of the mechanical stress field is reduced and so the formation of rims is also reduced compared to previously-proposed data storage devices.

[0011]Preferably, a thickness of the data storage medium is at least 5 nm. When the thickness of the data storage medium is in the range of 5 nm to 20 nm, for example, the proximity of the tip that is used in the production of an indentation mark in such a medium relative to the support layer is increased than if a thicker layer were used for the data storage medium. In this case, the mechanical stress field is absorbed more by the support layer, rather than material of the data storage medium at an increasing depth in the axis of tip penetration which would be the case for thicker layers of the data storage medium, and, thus, rim suppression would be expected to be enhanced.

[0012]Desirably, the support layer comprises a polymer material having a glass transition temperature that is lower than room temperature. Since the viscosity of the polymer material used for the support layer has a glass transition temperature lower than room temperature, it would react to the mechanical stress field created in the data storage medium, when an indentation mark is formed thereon by way of a tip, by yielding and / or flowing. Accordingly, the back-action of the mechanical stress field and the formation of a rim around the indentation mark would be reduced.

[0015]Desirably, in the step of forming the data storage medium on the support layer, surface energy-driven phase separation is used. Since the data storage medium and the support layer do not have to be made in separate steps, ease of fabrication is facilitated.

Problems solved by technology

Thus, the noise associated to the non-indentation marks or logical 0's may be increased, which causes lowering of the signal-to-noise (SNR) ratio.

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