High density single transistor ferroelectric non-volatile memory
First Claim
1. A ferroelectric memory cell, comprising:
- a semiconductor substrate having;
a source that serves both as the source for the ferroelectric memory cell and the source for an adjacent memory cell;
a drain in a spaced apart configuration with respect to the source and drains and sources of adjacent ferroelectric memory cells, wherein the drain is not included as a component of the adjacent ferroelectric memory cell; and
a channel;
a gate oxide substantially covering the drain, source, and channel;
a ferroelectric gate unit positioned on said gate oxide layer, the ferroelectric gate unit asymmetrically overlying the drain with respect to the source, the ferroelectric gate unit comprising;
a bottom electrode in electrical communication with said drain;
a top electrode;
a ferroelectric layer disposed between said bottom and said top electrode; and
a sealing layer disposed on each side of said ferroelectric gate unit; and
an upper conductive layer disposed on said ferroelectric gate unit and a portion of said gate oxide layer such that said upper conductive layer and said top electrode of said ferroelectric gate unit are in electrical communication.
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Abstract
A single transistor ferroelectric memory (“FEM”) cell, useful for high density ferroelectric random access memory (“FRAM”) applications, and a method for making the same, are herein disclosed. The FEM cell comprises a FEM gate unit having a top electrode, a ferroelectric material layer, and a bottom electrode. The FEM gate unit is disposed above a semiconductor substrate having defined on it a well region and channel of a first conductive type and a source and drain of a second conductive type. A conductive upper polysilicon layer covers both the FEM gate unit and a portion of the source region and is in electrical communication with the top electrode of the FEM gate unit. The drain is in electrical communication with the bottom electrode of the FEM gate unit and serves as the bit line for the FEM memory cell. The source is shared between the present memory cell and an adjacent cell.
30 Citations
19 Claims
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1. A ferroelectric memory cell, comprising:
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a semiconductor substrate having; a source that serves both as the source for the ferroelectric memory cell and the source for an adjacent memory cell; a drain in a spaced apart configuration with respect to the source and drains and sources of adjacent ferroelectric memory cells, wherein the drain is not included as a component of the adjacent ferroelectric memory cell; and a channel; a gate oxide substantially covering the drain, source, and channel; a ferroelectric gate unit positioned on said gate oxide layer, the ferroelectric gate unit asymmetrically overlying the drain with respect to the source, the ferroelectric gate unit comprising; a bottom electrode in electrical communication with said drain; a top electrode; a ferroelectric layer disposed between said bottom and said top electrode; and a sealing layer disposed on each side of said ferroelectric gate unit; and an upper conductive layer disposed on said ferroelectric gate unit and a portion of said gate oxide layer such that said upper conductive layer and said top electrode of said ferroelectric gate unit are in electrical communication. - View Dependent Claims (2, 15)
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3. A ferroelectric memory cell array, comprising:
first and second ferroelectric memory cells that are positioned adjacent one another on a semiconductor substrate, the first ferroelectric memory cell including; a source defined in the semiconductor substrate that is configured for use as the source for both the first and second ferroelectric memory cells; a first drain defined in the semiconductor substrate in a spaced apart configuration with respect to both a second drain of the second ferroelectric memory cell and the source, wherein the first drain is not included as a component of the second ferroelectric memory cell; a channel defined in the semiconductor substrate; a gate oxide substantially covering the first drain, source, and channel; a ferroelectric gate unit positioned on said gate oxide layer, the ferroelectric gate unit asymmetrically overlying the first drain with respect to the source, the ferroelectric gate unit comprising; a bottom electrode in electrical communication with the first drain; a top electrode; a ferroelectric layer disposed between said bottom and said top electrode; and a sealing layer disposed on each side of said ferroelectric gate unit; and an upper conductive layer disposed on said ferroelectric gate unit and a portion of said gate oxide layer such that said upper conductive layer and said top electrode of said ferroelectric gate unit are in electrical communication. - View Dependent Claims (4)
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5. A ferroelectric memory cell comprising:
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a semiconductor substrate having; a single source that serves as the source for both the ferroelectric memory cell and an adjacent ferroelectric memory cell; a drain that is spaced apart from the source and from drains and sources of adjacent ferroelectric memory cells, wherein the drain is not shared with the adjacent ferroelectric memory cell; and a channel defined between the source and the drain; a gate oxide substantially covering the drain, source, and channel; a ferroelectric gate unit comprising a top electrode, a layer of ferroelectric material, and a bottom electrode, the ferroelectric gate unit being positioned on the gate oxide, wherein the ferroelectric gate unit substantially overlies the entirety of the drain, and wherein the ferroelectric gate unit overlies only a portion of the source; and means for controlling the polarization of said layer of ferroelectric material. - View Dependent Claims (6, 7, 8)
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9. A single transistor ferroelectric memory cell, comprising:
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a semiconductor substrate having defined thereon; a first conductive region of a first conductive type; a source of a second conductive type defined in said first conductive region, said source sized and configured to comprise the source of the ferroelectric memory cell and the source of an adjacent ferroelectric memory cell; and a drain also of a second conductive type defined in said first conductive region, said drain being spaced apart from said source such that a channel region comprising a portion of said first conductive region is defined between said source and said drain, said drain also being spaced apart from sources and drains of adjacent ferroelectric memory cells, wherein said drain is not shared with adjacent ferroelectric memory cells; a gate oxide layer disposal on said semiconductor substrate to cover the entirety of said drain, channel region, and source; a ferroelectric gate unit positioned on said gate oxide layer such that the ferroelectric gate unit overlies a relatively greater portion of the drain than the source, the ferroelectric gate unit comprising; a bottom electrode in electrical communication with said drain; a top electrode; a ferroelectric layer disposed between said bottom and said top electrode; and a sealing layer disposed on each side of said ferroelectric gate unit; and an upper conductive layer disposal on said ferroelectric gate unit and a portion of said gate oxide layer such that said upper conductive layer and said top electrode of said ferroelectric gate unit are in electrical communication. - View Dependent Claims (10, 11, 12, 13, 14, 16, 17, 18, 19)
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Specification