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Electron Beam Addressable Memory by Void Formation

IP.com Disclosure Number: IPCOM000079671D
Original Publication Date: 1973-Aug-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Chaudhari, P: AUTHOR [+2]

Abstract

In a beam-addressable memory it is proposed to utilize the presence or absence of voids in recording and reading information. The memory consists of a layered structure or sandwich formed by having top and bottom layers of a material exhibiting low-vapor pressure and high strength, e.g., thin carbon, SiO foil, and having a center layer of high-vapor pressure material with a low-heat conductivity, such as amorphous chalcogenides or amorphous polymers. An electron beam is employed to melt a desired region locally to form a void in the center layer. Illustrative materials for the center layer are selenium, tellurium and sulphur.

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Electron Beam Addressable Memory by Void Formation

In a beam-addressable memory it is proposed to utilize the presence or absence of voids in recording and reading information. The memory consists of a layered structure or sandwich formed by having top and bottom layers of a material exhibiting low-vapor pressure and high strength, e.g., thin carbon, SiO foil, and having a center layer of high-vapor pressure material with a low-heat conductivity, such as amorphous chalcogenides or amorphous polymers. An electron beam is employed to melt a desired region locally to form a void in the center layer. Illustrative materials for the center layer are selenium, tellurium and sulphur.

Presence of voids can be read by an electron-beam transmission characteristic, because of their low-mass absorption. Erasure of all voids is achieved by thermal heating of the sandwich to the flow stage (glass transmission temperature) of the center layer. Erasure of individual voids is achieved, by local heating with an electron beam of moderate intensity to get local flow of the material.

In such a system, the center layer is vaporized locally and the gaseous material is constrained from escape into the vacuum of the system upon writing or void creation. Exemplary voids of 1 micron and less diameter may be formed in a sandwich of C-Se-C and of SiO(2)-Se-SiO(2) (approx.= 100-200-100 Angstroms), wherein the sandwich is held at a temperature < 50 degrees C with the center layer being amorphou...