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Read Write Memory Using Special Metal Al(2)O(3) SiO(2) Structures

IP.com Disclosure Number: IPCOM000074484D
Original Publication Date: 1971-May-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Chou, NJ: AUTHOR [+4]

Abstract

A device for improving the switching characteristics of an FET memory element has been devised which relies upon the use of a gate electrode of a metal having a high work function (at least 4.5eV) in conjunction with a gamma-Al(2)O(3) layer and an SiO(2) layer.

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Read Write Memory Using Special Metal Al(2)O(3) SiO(2) Structures

A device for improving the switching characteristics of an FET memory element has been devised which relies upon the use of a gate electrode of a metal having a high work function (at least 4.5eV) in conjunction with a gamma- Al(2)O(3) layer and an SiO(2) layer.

As shown in Fig. 1, a typical FET device comprises a source region s and a drain region d between which is a layer of SiO(2). Superimposed upon the SiO(2)layer is a layer of gamma-Al(2)O(3) and a metal electrode, such as Hg, Ni, Rh, Au, etc., having a work function of 4.5eV or greater.

Fig. 2 demonstrates the improved reversibility switching characteristic of an FET device when a higher work function material is used for the gate. When a "write" pulse of 60 volts and of 3 mu seconds duration is applied to an FET memory element in an array, the flat band voltage for that FET element is shifted from the "0" state of the FET element which is 10 volts to the "1" state which is 16 volts. When a read pulse of -60 volts and 3 mu seconds in duration is applied, the FET memory element switches to a flat band voltage of 10 volts. Prior to the use of such a high work function, switching was irreversible, that is, switching was only unidirectional. The use of the high work function metal as a gate permits switching to two distinct states, a necessity for a read-write memory.

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