Non-volatile memory cell having pinch-off ferroelectric field effect transistor
The disclosed technology relates generally to non-volatile memory devices, and more particularly to ferroelectric non-volatile memory devices. In one aspect, a non-volatile memory cell includes a pinch-off ferroelectric memory FET and at least one select device electrically connected in series to the pinch-off ferroelectric memory FET.
1. A non-volatile memory cell, comprising:
a pinch-off ferroelectric field effect transistor (FET) comprising a channel layer electrically connecting a source region and a drain region, wherein each of the channel layer, the source region and the drain region is formed of a semiconductor region doped with a first dopant type; and
at least one select device electrically connected in series to the pinch-off ferroelectric FET.
2. The non-volatile memory cell according to claim 1 , wherein the at least one select device comprises at least one select transistor.
3. The non-volatile memory cell according to claim 2 , wherein the at least one select device comprises a select transistor having a channel layer formed of a semiconductor region doped with a second dopant type opposite the first dopant type, the channel layer of the select transistor electrically connecting a source region and a drain region each doped with the first dopant type, wherein the drain region of the select transistor and the source region of the pinch-off ferroelectric FET are formed of a common highly doped region.
4. The non-volatile memory cell according to claim 3 , wherein the common highly doped region is electrically floating.
5. The non-volatile memory cell according to claim 3 , wherein the pinch-off ferroelectric FET comprises:
a ferroelectric gate stack comprising at least one ferroelectric layer and a gate electrode formed on the at least one ferroelectric layer;
an n-type source region and an n-type drain region; and
an n-type channel layer electrically connecting the n-type source region and the n-type drain region,
wherein the pinch-off ferroelectric FET has a negative threshold voltage, and
wherein the at least one select transistor is an n-MOS transistor.
6. The non-volatile memory cell according to claim 5 , wherein each of the n-type source and drain regions of the pinch-off ferroelectric FET comprises a highly doped n + region.
7. The non-volatile memory cell according to claim 6 , wherein the at least one select device comprises an n-type source region and an n-type drain region each comprising a highly doped n + region.
8. The non-volatile memory cell according to claim 7 , wherein the n-type drain region of the select device serves as the n-type source region of the pinch-off ferroelectric FET.
9. The non-volatile memory cell according to claim 5 , wherein the pinch-off ferroelectric FET further comprises at least one dielectric layer interposed between the at least one ferroelectric layer and the n-type channel and/or interposed between the at least one ferroelectric layer and the gate electrode.
10. The non-volatile memory cell according to claim 5 , wherein the n-type channel layer is formed in in a counterdoped n-type substrate region formed in a p-type substrate.
11. The non-volatile memory cell according to claim 5 , wherein the n-type channel layer is formed in an n-type region under the ferroelectric gate stack, and wherein the n-type region is formed on a p-type substrate or an insulator.
12. The non-volatile memory cell according to claim 3 , wherein the at least select one select device and the pinch-off ferroelectric FET are electrically connected in series between a bit line and an array ground.
13. The non-volatile memory cell according to claim 12 , wherein the pinch-off ferroelectric FET is positioned at the bit line side and the select device is positioned at the side of the array ground.
14. The non-volatile memory cell according to claim 12 , wherein the pinch-off ferroelectric FET is positioned at the side of the array ground and the select device is positioned at the bit line side.
15. A non-volatile memory array, comprising a plurality of memory cells according to claim 1 , logically arranged in rows and columns.
16. A method of operation of a non-volatile memory device according to claim 1 , wherein data of the ferroelectric pinch-off memory gate stack in accumulation mode is read out without applying a voltage to the gate electrode of the ferroelectric pinch-off memory FET.