Ferroelectric memory cell with shunted ferroelectric capacitor and method of making same
First Claim
1. A ferroelectric memory comprising:
- a transistor having a source/drain;
a capacitor having a first electrode and a second electrode, said first electrode connected to said source/drain of said transistor to create a node that is isolated when said transistor is off; and
a shunt system for directly electrically connecting said isolated node and said second electrode of said capacitor at a predetermined time to essentially equalize the voltages on said first and second electrodes of said capacitor during said predetermined time;
wherein said memory includes a plurality of memory cells, each of said memory cells including one of said isolated nodes, and said shunt system comprises;
a first shunt device for directly electrically connecting said one of said isolated nodes in each of said cells to one of said isolated nodes in another of one of said cells during said predetermined time; and
a second shunt device for directly electrically connecting at least one of said isolated nodes to said second electrode of said capacitor during said predetermined time.
1 Assignment
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Accused Products
Abstract
A ferroelectric memory includes a transistor having a source/drain, a capacitor having a first electrode and a second electrode, and a plate line connected to the second electrode. The first electrode is connected to the source/drain of the transistor to create a node that is isolated when the transistor is off. A shunt system directly electrically connects the isolated node and the second electrode of said capacitor at a predetermined time to essentially equalize the voltages on the first and second electrodes of said capacitor during the predetermined time. In different embodiments the shunt is a Schottky diode, a resistor, and a pair of back-to-back diodes and a transistor. In the embodiment in which the shunt is a transistor, the shunt line connected to the shunt transistor gate is boosted, there is a shunt transistor connecting each isolated node in a portion of the memory, to the adjacent isolated node, and every eight to thirty-two isolated nodes, another shunt transistor connects the chain of isolated nodes to the plate line.
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Citations
18 Claims
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1. A ferroelectric memory comprising:
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a transistor having a source/drain; a capacitor having a first electrode and a second electrode, said first electrode connected to said source/drain of said transistor to create a node that is isolated when said transistor is off; and a shunt system for directly electrically connecting said isolated node and said second electrode of said capacitor at a predetermined time to essentially equalize the voltages on said first and second electrodes of said capacitor during said predetermined time; wherein said memory includes a plurality of memory cells, each of said memory cells including one of said isolated nodes, and said shunt system comprises; a first shunt device for directly electrically connecting said one of said isolated nodes in each of said cells to one of said isolated nodes in another of one of said cells during said predetermined time; and a second shunt device for directly electrically connecting at least one of said isolated nodes to said second electrode of said capacitor during said predetermined time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A ferroelectric memory cell comprising:
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a transistor having a source/drain; a capacitor having a first electrode and a second electrode, said first electrode connected to said source/drain of said transistor to create a node that is isolated when said transistor is off; and a shunt device for directly electrically connecting said isolated node and said second electrode of said capacitor at a predetermined time to essentially equalize the voltages on said first and second electrodes of said capacitor at said predetermined time, said shunt device selected from the group consisting of;
a Schottky diode and a pair of back-to-back diodes.
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11. A method of operating a ferroelectric memory including:
- a bit line, a word line, and a plate line;
a memory cell comprising a transistor having a first source/drain, a second source/drain, and a gate; and
a capacitor having a first electrode and a second electrode, with said first electrode connected to said first source/drain of said transistor to create a node that is isolated when said transistor is off;
wherein said bit line is connected to said second source drain, said word line is connected to said gate, and said plate line is connected to said second electrode;
said method comprising the steps of;
directly electrically connecting said isolated node and said second electrode of said capacitor at a predetermined time to essentially equalize the voltages on said first and second electrodes of said capacitor at said predetermined time;
performing a write/rewrite cycle on said memory cell, including the step of raising the voltage on said word line; and
at the end of said write/rewrite cycle, adjusting the voltage on said bit line to the same voltage as the voltage on said plate line. - View Dependent Claims (12)
- a bit line, a word line, and a plate line;
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13. A method of manufacturing a ferroelectric memory comprising a transistor having a gate and source/drain, a word line connected to said gate, a capacitor having a first electrode and a second electrode with said first electrode connected to said source/drain of said transistor to create a node that is isolated when said transistor is off, and a shunt for directly electrically connecting said second electrode and said isolated node, said method comprising the steps of:
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fabricating a word line by forming a conductive layer and patterning said conductive layer; and at the same time and in the same process steps as said step of fabricating said word line, fabricating said shunt line. - View Dependent Claims (14)
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15. A ferroelectric memory comprising:
- a supply voltage power source having an output voltage;
a transistor having a source/drain and a gate;
a capacitor having a first electrode and a second electrode, said first electrode connected to said source/drain of said transistor to create a node that is isolated when said transistor is off;
a shunt system for directly electrically connecting said isolated node and said second electrode of said capacitor at a predetermined time to essentially equalize the voltages on said first and second electrodes of said capacitor during said predetermined time; and
said shunt system further includes;a shunt line connected to the gate of said shunt transistor; and a signal generator for applying a shunt line signal to said shunt line, which signal is boosted above the voltage of said output voltage for at least a portion of said predetermined time.
- a supply voltage power source having an output voltage;
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16. A ferroelectric memory comprising:
- a transistor having a source/drain;
a capacitor having a first electrode and a second electrode, said first electrode connected to said source/drain of said transistor to create a node that is isolated when said transistor is off; and
a shunt system for directly electrically connecting said isolated node and said second electrode of said capacitor at a predetermined time to essentially equalize the voltages on said first and second electrodes of said capacitor during said predetermined time;
wherein said memory includes a memory cell having two of said transistors, two of said capacitors, and two of said isolated nodes, and said shunt system comprises a shunt device for directly electrically connecting said two isolated nodes.
- a transistor having a source/drain;
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17. A method of operating a ferroelectric memory including;
- a supply voltage power source having an output voltage;
a shunt transistor including a gate;
a shunt line connected to the gate of said shunt transistor; and
a memory cell comprising a transistor having a first source/drain and a capacitor having a first electrode and a second electrode, with said first electrode connected to said source/drain of said transistor to create a node that is isolated when said transistor is off, said method comprising the step of;
directly electrically connecting said isolated node and said second electrode of said capacitor via said shunt transistor by applying, at a predetermined time, a voltage to said shunt line that is higher than said output voltage to essentially equalize the voltages on said first and second electrodes of said capacitor at said predetermined time.
- a supply voltage power source having an output voltage;
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18. A method of operating a ferroelectric memory including a memory cell comprising a transistor having a first source/drain and a capacitor having a first electrode and a second electrode, with said first electrode connected to said source/drain of said transistor to create a node that is isolated when said transistor is off, said memory cell including two of said transistors, two of said capacitors, and two of said isolated nodes, said method comprising the steps of:
- directly electrically connecting each of said isolated nodes to the second electrode of the corresponding capacitor at a predetermined time; and
directly electrically connecting said isolated nodes at said predetermined time;
to essentially equalize the voltages on said first and second electrodes of said capacitor at said predetermined time.
- directly electrically connecting each of said isolated nodes to the second electrode of the corresponding capacitor at a predetermined time; and
Specification