Ferroelectric memory devices having linear reference cells therein and methods of operating same
First Claim
1. A ferroelectric memory device, comprising:
- a ferroelectric memory cell containing an access transistor and a ferroelectric storage capacitor therein;
a reference cell containing an access transistor and a linear storage capacitor therein;
a sense amplifier having first and second inputs electrically coupled to the access transistors of said ferroelectric memory cell and said reference cell, respectively; and
a reset transistor electrically connected in series between the second input of said sense amplifier and a reference signal line.
2 Assignments
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Accused Products
Abstract
Nonvolatile ferroelectric-based integrated circuit memory devices utilize reference cells containing linear storage capacitors to inhibit deterioration in reliability typically associated with ferroelectric capacitors which have undergone excessive polarization cycling. These linear storage capacitors are preferably coupled to respective plate lines so that efficient reading operations may be performed. In particular, a nonvolatile memory device is preferably provided which contains a ferroelectric memory cell having an access transistor and a ferroelectric storage capacitor therein. A reference cell is also provided and this reference cell contains an access transistor and a linear storage capacitor therein. In addition, a sense amplifier is provided which has first and second inputs electrically coupled to the access transistors of the ferroelectric memory cell and the reference cell, respectively. To improve the efficiency of reading operations, a reset transistor is preferably provided and this transistor is electrically connected in series between the second input of the sense amplifier and a reference signal line (e.g., ground signal line).
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Citations
17 Claims
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1. A ferroelectric memory device, comprising:
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a ferroelectric memory cell containing an access transistor and a ferroelectric storage capacitor therein; a reference cell containing an access transistor and a linear storage capacitor therein; a sense amplifier having first and second inputs electrically coupled to the access transistors of said ferroelectric memory cell and said reference cell, respectively; and a reset transistor electrically connected in series between the second input of said sense amplifier and a reference signal line. - View Dependent Claims (2, 3, 4, 5)
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6. A nonvolatile memory device, comprising:
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a bit line; a reference bit line; a plate line; a reference plate line; a ferroelectric memory cell containing an access transistor having a source region electrically connected to said bit line and a ferroelectric storage capacitor having a plate electrode electrically connected to said plate line; a reference cell containing an access transistor having a source region electrically connected to said reference bit line and a linear storage capacitor having a plate electrode electrically connected to said reference plate line; and a sense amplifier having first and second inputs electrically coupled to said bit line and said reference bit line, respectively. - View Dependent Claims (7, 8)
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9. In an integrated circuit memory device containing a ferroelectric memory cell, a linear reference cell and a sense amplifier electrically coupled to the ferroelectric memory cell and the linear reference cell by a bit line and reference bit line, respectively, a method of reading a state of the ferroelectric memory cell, comprising the steps of:
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discharging a linear storage capacitor in the linear reference cell; driving the bit line to a first potential by electrically connecting a storage electrode of a ferroelectric capacitor in the ferroelectric memory cell to the bit line while simultaneously driving a plate electrode of the ferroelectric capacitor to a first plate potential; driving the reference bit line to a second potential by electrically connecting a storage electrode of the discharged linear storage capacitor in the linear reference cell to the reference bit line while simultaneously driving a plate electrode of the discharged linear storage capacitor to a second plate potential; and driving the bit line and reference bit line to respective opposite potentials by sensing and amplifying a difference in potential between the bit line and reference bit line. - View Dependent Claims (10, 11, 12)
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13. In an integrated circuit memory device containing a ferroelectric memory cell, a linear reference cell and a sense amplifier electrically coupled to the ferroelectric memory cell and the linear reference cell by a bit line and reference bit line, respectively, a method of operating the memory device, comprising the steps of:
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driving the bit line to a first potential by electrically connecting a storage electrode of a ferroelectric capacitor in the ferroelectric memory cell to the bit line while simultaneously driving a plate electrode of the ferroelectric capacitor to a first plate potential; driving the reference bit line to a second potential by electrically connecting a storage electrode of the linear storage capacitor in the linear reference cell to the reference bit line while simultaneously driving a plate electrode of the linear storage capacitor to a second plate potential; and driving the bit line and reference bit line to respective opposite potentials by sensing and amplifying a difference in potential between the bit line and reference bit line. - View Dependent Claims (14, 15, 16, 17)
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Specification