Antiferroelectric memory devices and methods of making the same
An antiferroelectric memory device includes at least one antiferroelectric memory cell. Each of the at least one antiferroelectric memory cell includes a first electrode, a second electrode and a stack containing an antiferroelectric layer and a doped semiconductor layer or a ferroelectric layer located between the first and the second electrodes.
1. A method of forming an antiferroelectric memory device, comprising:
forming a continuous layer stack including a first continuous electrically conductive layer, a continuous symmetry-breaking material layer, and a continuous antiferroelectric layer, wherein the continuous symmetry-breaking material layer comprises a continuous doped semiconductor layer or a continuous ferroelectric layer located above or below the continuous antiferroelectric layer, and in contact with the continuous antiferroelectric layer;
patterning the continuous layer stack into first electrically conductive lines, symmetry-breaking material rails, and antiferroelectric rails by forming first dielectric rails through the continuous layer stack;
depositing a second continuous electrically conductive layer over the symmetry-breaking material rails and the antiferroelectric rails; and
patterning the second continuous electrically conductive layer, the symmetry-breaking material rails, and antiferroelectric rails into second electrically conductive lines, symmetry-breaking material layers, and antiferroelectric layers, respectively.
2. The method of claim 1 , wherein the continuous symmetry-breaking material layer comprises the continuous doped semiconductor layer.
3. The method of claim 1 , wherein the continuous symmetry-breaking material layer comprises the continuous ferroelectric layer.
4. The method of claim 1 , wherein a non-zero electrical field is present across each of the antiferroelectric layers under a zero electrical bias condition between a most proximal one of the first electrically conductive lines and a most proximal one of the second electrically conductive lines.
5. The method of claim 1 , wherein:
each antiferroelectric layer has two electrical polarization states at zero external voltage bias across an underlying one of the first electrically conductive lines and an overlying one of the second electrically conductive lines;
a first electrical polarization state of the antiferroelectric layer has a first net non-zero electrical polarization pointing toward the first electrode or the second electrode; and
a second electrical polarization state of the antiferroelectric layer has a second net non-zero electrical polarization having a greater magnitude than the first net non-zero electrical polarization and having a same direction as the first net non-zero electrical polarization.
6. The method of claim 1 , further comprising:
forming first dielectric rails between each neighboring stacks of a respective one of the first electrically conductive lines, a respective one of the symmetry-breaking material rails, and a respective one of the antiferroelectric rails; and
forming second dielectric rails between each neighboring stack of a respective one of the second electrically conductive lines, a respective column of the symmetry-breaking material layers, and a respective column of the antiferroelectric layers.