Storage device
A storage device includes a first electrode, a second electrode, a first dielectric layer between the first and second electrodes and including oxygen and at least one of hafnium and zirconium, a second dielectric layer between the first electrode and the first dielectric layer, and an intermediate region between the first and second dielectric layers and in which a plurality of metallic portions are provided.
1 . A storage device, comprising:
a first electrode;
a second electrode;
a first dielectric layer between the first and second electrodes, and comprising a first dielectric material including oxygen and at least one of hafnium and zirconium;
a second dielectric layer between the first electrode and the first dielectric layer, and comprising a second dielectric material different from the first dielectric material; and
an intermediate region between the first and second dielectric layers and in which a plurality of discrete metallic portions are provided,
wherein the discrete metallic portions include metallic elements,
wherein each of the first and second dielectric layers includes metallic elements that are same as the metallic elements included in the plurality of discrete metallic portions,
a concentration of the metallic elements in the first dielectric material decreases as a distance from the intermediate region increases, and
a concentration of the metallic elements in the second dielectric material decreases as a distance from the intermediate region increases.
2 . The storage device according to claim 1 , wherein the intermediate region stores charges when a voltage applied to the second electrode is higher than a voltage applied to the first electrode, and erases charges when a voltage applied to the second electrode is less than a voltage applied to the first electrode.
3 . The storage device according to claim 1 , wherein the metallic portions include titanium.
4 . The storage device according to claim 3 , wherein the intermediate region includes nitrogen.
5 . The storage device according to claim 1 , wherein the first dielectric layer has anti-ferroelectricity.
6 . The storage device according to claim 1 , wherein the first dielectric layer has a higher relative permittivity than the second dielectric layer.
7 . The storage device according to claim 1 , wherein the first dielectric layer includes at least one of silicon and aluminum.
8 . The storage device according to claim 1 , wherein the first dielectric layer includes both hafnium and zirconium, and a concentration of zirconium in the first dielectric layer is higher than a concentration of hafnium in the first dielectric layer.
9 . The storage device according to claim 1 , wherein the second dielectric layer includes silicon and oxygen.
10 . The storage device according to claim 1 , wherein the second dielectric layer has a thickness of 4 nm or less.
11 . A storage device, comprising:
a first electrode;
a second electrode;
a first dielectric layer between the first and second electrodes, and comprising a first dielectric material including oxygen and at least one of hafnium and zirconium;
a second dielectric layer between the first electrode and the first dielectric layer, and comprising a second dielectric material different from the first dielectric material; and
an intermediate region between the first and second dielectric layers and including a plurality of discrete metallic elements,
wherein each of the first and second dielectric layers includes metallic elements that are same as the metallic elements included in the intermediate region,
a concentration of the metallic elements in the first dielectric material decreases as a distance from the intermediate region increases,
a concentration of the metallic elements in the second dielectric material decreases as a distance from the intermediate region increases, and
wherein
the intermediate region transitions to a first state when a voltage applied to the second electrode is higher than a voltage applied to the first electrode,
the intermediate region transitions to a second state when a voltage applied to the second electrode is lower than a voltage applied to the first electrode, and
an absolute value of the voltage applied to the second electrode in transition to the first state is greater than an absolute value of the voltage applied to the second electrode in transition to the second state.
12 . The storage device according to claim 11 , wherein the intermediate region includes titanium as the metallic elements.
13 . The storage device according to claim 12 , wherein the intermediate region includes nitrogen.
14 . The storage device according to claim 11 , wherein the first dielectric layer has anti-ferroelectricity.
15 . The storage device according to claim 11 , wherein the first dielectric layer has a higher relative permittivity than the second dielectric layer.
16 . The storage device according to claim 11 , wherein the first dielectric layer includes at least one of silicon and aluminum.
17 . The storage device according to claim 11 , wherein the first dielectric layer includes both hafnium and zirconium, and a concentration of zirconium in the first dielectric layer is higher than a concentration of hafnium in the first dielectric layer.
18 . The storage device according to claim 11 , wherein the second dielectric layer includes silicon and oxygen.
19 . A storage device, comprising:
a plurality of first wirings extending along a first direction;
a plurality of second wirings extending along a second direction crossing the first direction; and
a plurality of memory cells, each of which is connected between one of the first wirings and one of the second wirings and includes a capacitor and a transistor connected in series, wherein the capacitor includes:
a first electrode,
a second electrode,
a first dielectric layer between the first and second electrodes, and comprising a first dielectric material including oxygen and at least one of hafnium and zirconium,
a second dielectric layer between the first electrode and the first dielectric layer, and comprising a second dielectric material different from the first dielectric material; and
an intermediate region between the first and second dielectric layers and in which a plurality of discrete metallic portions are provided,
wherein the discrete metallic portions include metallic elements,
wherein each of the first and second dielectric layers includes metallic elements that are same as the metallic elements included in the plurality of discrete metallic portions,
a concentration of the metallic elements in the first dielectric material decreases as a distance from the intermediate region increases, and
a concentration of the metallic elements in the second dielectric material decreases as a distance from the intermediate region increases.