Ferroelectric tunnel junction devices with internal biases for long retention
AssigneeApplied Materials, Inc.
InventorsMilan Pesic, Bastien Beltrando
Life of this patent
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Abstract
A ferroelectric tunnel junction (FTJ) memory device may include a first electrode and a ferroelectric layer comprising ferroelectric dipoles that may generate a first electric field. The first electric field may be oriented in a first direction when the device operates in an ON state. The device may also include a barrier layer that may generate a depolarizing second electric field that may be oriented in a second direction opposite of the first direction when the device operates in the ON state. The device may further include a second electrode. The first electrode and the second electrode may generate a third electric field that is oriented in the first direction when the device operates in the ON state.
Claims19
A ferroelectric tunnel junction (FTJ) memory device, the device comprising:
- a first electrode having first work function;
- a ferroelectric layer comprising ferroelectric dipoles that generates a first electric field, wherein the first electric field is oriented in a first direction when the device operates in an ON state, and the ferroelectric layer is between approximately 7.5 nm and 15.0 nm thick;
- a barrier layer that generates a depolarizing second electric field that is oriented in a second direction opposite of the first direction when the device operates in the ON state, wherein the barrier layer is between approximately 1.0 nm and 2.0 nm thick;
- and
- a second electrode having a second work function, wherein a difference between the first work function and the second work function generates a third electric field that is oriented in the first direction and that is greater than or equal to the depolarizing second electric field to cancel an effect of the depolarizing second electric field when the device operates in the ON state.
A method of forming a ferroelectric tunnel junction (FTJ) memory device, the method comprising:
- forming a first electrode having first work function;
- forming a ferroelectric layer comprising ferroelectric dipoles that generate a first electric field, wherein the first electric field is oriented in a first direction when the device operates in an ON state, and the ferroelectric layer is between approximately 7.5 nm and 15.0 nm thick;
- forming a barrier layer that generates a depolarizing second electric field that is oriented in a second direction opposite of the first direction when the device operates in the ON state, wherein the barrier layer is between approximately 1.0 nm and 2.0 nm thick;
- and
- forming a second electrode having a second work function, wherein a difference between the first work function and the second work function generates a third electric field that is oriented in the first direction and is greater than or equal to the depolarizing second electric field to cancel an effect of the depolarizing second electric field when the device operates in the ON state.
A ferroelectric tunnel junction (FTJ) memory device, the device comprising:
- a first electrode having a first work function;
- a ferroelectric layer having a thickness dFE and a dielectric permittivity kFE;
- a barrier layer having a thickness dIF and a dielectric permittivity kIF;
- and
- a second electrode having a second work function, wherein a difference between the first work function and the second work function generates an electric field that is at least
- Pr/kFEε0(1+kIFdFE/kFEdIF)−1,
- where Pr represents a remnant polarization, and ε0 represents a vacuum permittivity.
Dependencies are inferred from the claim text.