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Density Improvement in MNOS Array by Overlapping Gate Electrodes

IP.com Disclosure Number: IPCOM000083518D
Original Publication Date: 1975-Jun-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Kenyon, RA: AUTHOR [+2]

Abstract

A nonvolatile metal-nitride-oxide semiconductor (MNOS) memory array of variable threshold insulative gate, field-effect transistor devices is described. The described array has a significantly increased word line packing density, resulting in more usable cells per unit area.

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Density Improvement in MNOS Array by Overlapping Gate Electrodes

A nonvolatile metal-nitride-oxide semiconductor (MNOS) memory array of variable threshold insulative gate, field-effect transistor devices is described. The described array has a significantly increased word line packing density, resulting in more usable cells per unit area.

The array shown in.the figure comprises a plurality of field-effect transistors T11, T12, T21, T22, T31, T32, T41, and T42 having common source and drain regions 17, 18, 19, and 20 and multiple parallel gates 28a, 28b, 16a, and 16b between these regions, with each gate electrically influencing a portion of the underlying semiconductor substantially equal to the width of the gate electrode. Each gate electrode is further separated from any adjacent gate, by a space 24 smaller than the optical resolution of the light used to produce the gate electrode.

The array is produced as follows: The sources 17 and 19 and the drains 18 and 20, respectively, are diffused into the body of silicon 11 and the entire device coated with approximately 5,000 angstroms of silicon dioxide, following which a layer of photoresist, not shown, is provided over the surface of the oxide and exposed to light in accordance with well known techniques. Elongated gate channels are etched through the oxide layer between the diffused bit lines. Once these channels have been produced, suitable gate oxides composed of silicon nitride and silicon dioxide are layed do...