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US 7,031,180 B2Granted
Method of reading data in ferroelectric memory device and ferroelectric memory device
AssigneeSeiko Epson Corporation
InventorsJunichi Karasawa, Takeshi Kijima, Eiji Natori
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Abstract
A method of reading data in a ferroelectric memory device includes applying a read voltage to a ferroelectric capacitor, and detecting a voltage that reflects an amount of a dynamic change in capacitance of the ferroelectric capacitor to which the read voltage is applied. Since a voltage difference ΔV occurs at a time T between the case where the polarization of a memory cell which has stored first data is not reversed and the case where the polarization of a memory cell which has stored second data is reversed, a read margin increases.
Claims12
A method of reading data in a ferroelectric memory device, comprising:
- applying a read voltage to a ferroelectric capacitor;
- and
- detecting a voltage that reflects an amount of a dynamic change in capacitance of the ferroelectric capacitor to which the read voltage is applied,
- the ferroelectric capacitor stores one of first data and second data, the first data being stored based on spontaneous polarization of a first polarity when a voltage applied to the ferroelectric capacitor is returned from a write voltage of the first polarity to 0 V, the second data being stored based on spontaneous polarization of a second polarity when the voltage applied to the ferroelectric capacitor is returned from a write voltage of the second polarity to 0 V, and
- polarity of polarization of the ferroelectric capacitor which has stored the first data is not reversed, and polarity of polarization of the ferroelectric capacitor which has stored the second data is reversed, when a voltage of the first polarity is applied to the ferroelectric capacitor as the read voltage.
2 more elements
A method of reading data in a ferroelectric memory device, comprising:
- applying a read voltage to a ferroelectric capacitor;
- and
- detecting a voltage that reflects an amount of a dynamic change in capacitance of the ferroelectric capacitor to which the read voltage is applied,
- a voltage-rise curve includes a portion in which a voltage-rise gradient differs depending on whether a polarization value of the ferroelectric capacitor is a first value or a second value, the voltage-rise curve indicating a voltage rise of a sense line connected with the ferroelectric capacitor when the read voltage is applied to the ferroelectric capacitor, and a timing of detecting the voltage that reflects the amount of the dynamic change is set in a period specified by the portion in which the voltage-rise gradient differs.
1 more element
A ferroelectric memory device comprising:
- voltage applying section which applies a read voltage to a ferroelectric capacitor;
- and
- voltage detection section which detects a voltage that reflects an amount of a dynamic change in capacitance of the ferroelectric capacitor to which the read voltage is applied, a voltage-rise curve includes a portion in which a voltage-rise gradient differs depending on whether a polarization value of the ferroelectric capacitor is a first value or a second value, the voltage-rise curve indicating a voltage rise of a sense line connected with the ferroelectric capacitor when the read voltage is applied to the ferroelectric capacitor, and a timing of detecting the voltage that reflects the amount of the dynamic change by the voltage detection section is set in a period specified by the portion in which the voltage-rise gradient differs.
A ferroelectric memory device comprising:
- a plurality of memory cells, each of the memory cells including a ferroelectric capacitor and a switching element;
- a plurality of wordlines, each of the wordlines extending in a first direction and being connected in common with a control terminal of the switching element in each of the memory cells arranged along the first direction;
- a plurality of bitlines, each of the bitlines extending in a second direction and being connected in common with one end of the switching element in each of the memory cells arranged along the second direction, the second direction intersecting the first direction;
- a plurality of sense lines, each of the sense lines extending in the second direction and being connected in common with one end of the ferroelectric capacitor and the other end of the switching element in each of the memory cells arranged in the second direction;
- a plurality of plate lines, each of the plate lines extending in the first direction and being connected in common with the other end of the ferroelectric capacitor in each of the memory cells arranged in the first direction;
- and
- a voltage detection section which detects a voltage of the sense lines in a specified period, when a read voltage is applied to the ferroelectric capacitor of at least one selected memory cell selected from among the plurality of memory cells, the specified period being specified by a portion of a voltage-rise curve in which a voltage-rise gradient differs depending on whether a polarization value of the ferroelectric capacitor is a first value or a second value, and the voltage-rise curve indicating a voltage rise of one of the sense lines connected with the ferroelectric capacitor of the selected memory cell.
4 more elements
Dependencies are inferred from the claim text.