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US 4,800,526 AGranted
Memory element for information storage and retrieval system and associated process
AssigneeGAF Corporation
InventorDavid F. Lewis
Life of this patent
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AssigneeGAF Corporation
InventorDavid F. Lewis
Estimating the term…
A memory element for an electron beam target comprising an electrically insulating support laminated to a conductive layer which, in turn, is laminated to a dielectric surface layer having a thickness less than 1 micrometer, e.g. 0.04-0.8 micrometer, a resistivity of at least 10.sup.16 ohm-cm and a dielectric strength of at least 10.sup.5 volts/cm; said dielectric surface layer comprising a material sensitive to electron beam irradiation and provided, essentially coplanar with its exposed surface, with focusing means or indicia in the form of shaped patterns that provide reference points for locating recording or retrieval points during electron beam exposure and scanning of the target surface. Writing is accomplished by irradiating with an electron beam either to develop a charge pattern or to alter the state of polymerization of cross-linking or both in a prescribed pattern for transmitting data. Where polymerization or cross-linking is involved, the material is altered such that subsequent contact with a solvent selectively removes the material in the state of lesser polymerization, leaving behind permanent islands of the unremoved material. By assigning a given logical meaning to the permanent islands or to the charge stored in the dielectric layer, for example, a dual character code is provided such that digital data can be stored. The focusing means or indicia allow addresses to be located in the memory element with sufficient precision that in excess of 10.sup.8 bits/cm.sup.2 can be recorded and retrieved.
A memory element for an information storage and retrieval system in which data is transferred by a scanning electron beam, wherein said element comprises an electrically conductive layer of an electrically conductive substance to which is laminated a layer of dielectric material, the latter having a thickness of less than 1 micrometer, a resistivity of at least 10.sup.16 ohm-cm, and a dielectric strength of at least 10.sup.5 volts/cm, means disposed essentially coplanar with the exposed surface of said insulating material layer for providing a focusing means for said electron beam, and means recognizable by said electron beam for providing spatial reference information to said system for enabling precise repeatable access to discrete locations for each bit of information in said memory element, whereby said element is capable of handling data with a resolution equal to at least 10.sup.8 bits/cm.sup.2.
A method for storing digital data using a modulatable scanning electron beam, said method comprising in combination the steps of providing a memory element having an electrically conductive layer of an electrically conductive substance to which is laminated a layer of dielectric material, the latter having a thickness of less than 1 micrometer, a resistivity of at least 10.sup.16 ohm-cm, a dielectric strength of at least 10.sup.5 volts/cm, and being a material subject to alteration of its surface properties when exposed to electron irradiation, such alteration resulting from selective polymerization and/or cross-linking, or selective depolymerization, of a monomer or polymer, scanning said electron beam over the exposed surface of said dielectric material while modulating said beam in accordance with the digital data to be stored for altering the surface properties of the dielectric material in correspondence with the instantaneous value of said data within discrete selected areas of said dielectric material relative to remaining unaltered areas of said dielectric material, subsequently treating said layer of dielectric material to create islands of said dielectric material by removing, as between said selected and remaining areas, said dielectric material having a lesser degree of polymerization and/or cross-linking, whereby the presence and absence of said islands represents the binary logical values of said data.
A memory element for an information retrieval system in which data is ready by a scanning electron beam, wherein said element comprises an electrically conductive layer of an electrically conductive substance to which is laminated dielectric material having altered surface areas the presence or absence of said altered areas representing the binary logical values of transmitted data, such alteration resulting from charged and uncharged areas or from selective areas of a higher degree of polymerization than existed in the unexposed dielectric material, said dielectric material having a maximum thickness of less than 1 micrometer, a resistivity of at least 10.sup.16 ohm/cm, and a dielectric strength of at least 10.sup.5 volts/cm, means disposed essentially coplanar with the exposed upper surface of said dielectric material for providing focusing means for said electron beam, and means recognizable by said electron beam for providing spatial reference information to said system for enabling precise repeatable access to the discrete locations of dielectric surface alteration for enabling reading of data present with a density of at least 10.sup.8 bits/cm.sup.2.
The memory element according to claim 43 wherein said indicia are formed of a metal foil of gold, platinum or copper.
Dependencies are inferred from the claim text.