Browse Prior Art Database

Nonvolatile Charge Storage Cell for Random Access Memory Applications

IP.com Disclosure Number: IPCOM000080729D
Original Publication Date: 1974-Feb-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Keshavan, BV: AUTHOR [+2]

Abstract

Described is a nonvolatile charge-storage device for random-access memory applications, in which the magnitudes of the low-threshold voltage and high-threshold voltage are not important, and fatigue with the shift in the threshold voltages is acceptable as the relative change in the high and low-threshold voltages is measured.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 64% of the total text.

Page 1 of 2

Nonvolatile Charge Storage Cell for Random Access Memory Applications

Described is a nonvolatile charge-storage device for random-access memory applications, in which the magnitudes of the low-threshold voltage and high- threshold voltage are not important, and fatigue with the shift in the threshold voltages is acceptable as the relative change in the high and low-threshold voltages is measured.

The structure is comprised of an N- type silicon body 10 having P-type epitaxial layer 11, into which N+ isolations diffusions 12 and N+ type bit sense line 13 are diffused therein. On the surface of the epitaxial layer 11 and partly coextensive therewith is provided a multiple layer, gate dielectric structure including a relatively thin layer of thermally grown silicon dioxide 14, over which is deposited a thicker layer 15 of polysilicon and which, in turn, is coated by a thicker layer 16 of silicon dioxide. The device is completed by applying a conductive metal word line 17. The additional layer of polysilicon in the gate structure enhances the switching speed of the device, making it viable for medium speed random-access memory applications.

To write into the cell, potentials of proper polarity are applied to the word line 17 and the diffused bit line 13, causing charges to be stored in the oxide-silicon interface.

Depending upon the applied voltages, the charge-storage device can be put into either a low threshold or a high-threshold state, causing the surface under ...