Ferroelectric memory devices with reduced edge defects and methods for forming the same
Embodiments of ferroelectric memory devices and methods for forming the ferroelectric memory devices are disclosed. In an example, a ferroelectric memory cell includes a first electrode, a second electrode, and a ferroelectric layer disposed between the first electrode and the second electrode. An edge region exposed by the first electrode and the second electrode is covered by at least one of a healing layer or a block layer.
1. A ferroelectric memory cell, comprising:
a first electrode;
a second electrode;
a ferroelectric layer disposed between the first electrode and the second electrode and comprising a pair of edge doped portions and a undoped portion between the pair of edge doped portion in a cross-sectional view, wherein
the ferroelectric layer comprises a pair of recessed portions; and
a healing layer, wherein the pair of edge doped portions of the ferroelectric layer and side walls of at least one of the first and second electrodes extending in a first direction are covered by the healing layer, wherein the first direction is perpendicular to an exposed surface of one of the pair of edge doped portions in contact with the healing layer, and a length of the ferroelectric layer extending in the first direction is less than that of each of the first and second electrodes, wherein the healing layer comprises a first material and a plurality of dopants of a second material, the second material being different from the first material.
2. The ferroelectric memory cell of claim 1 , wherein:
the healing layer comprises at least one of HfO x , ZrO x , AlO x , HfZrO x , HfSiO x , or TiAlO x , and has a thickness of about 5 Å to about 500 Å.
3. The ferroelectric memory cell of claim 1 , wherein the healing layer is a single layer and covers the pair of edge doped portions of the ferroelectric layer and all side walls of the first and second electrodes extending the first direction.
4. The ferroelectric memory cell of claim 1 , wherein the healing layer is doped with at least one of Hf, Zr, Ti, Al, Si, V, O, H, Nb, Ta, Y, gadolinium (Gd), or La.
5. The ferroelectric memory cell of claim 1 , wherein:
the first electrode and the second electrode each comprises at least one of titanium nitride (TiN), titanium silicon nitride (TiSiN x ), titanium aluminum nitride (TiAlN x ), titanium carbon nitride (TiCN x ), tantalum nitride (TaN x ), tantalum silicon nitride (TaSiN x ), tantalum aluminum nitride (TaAlN x ), tungsten nitride (WN x ), tungsten silicide (WSi x ), tungsten carbide (WCN x ), ruthenium (Ru), or ruthenium oxide (RuO x ); and
the ferroelectric layer comprises at least one of aluminum (Al), hafnium (Hf), zirconium (Zr), oxygen (O), or titanium (Ti), and is doped with at least one of Hf, Zr, Ti, Al, silicon (Si), hydrogen (H), O, vanadium (V), niobium (Nb), tantalum (Ta), yttrium (Y), or lanthanum (La).
6. The ferroelectric memory cell of claim 1 , wherein the healing layer covers an entire lateral surface of at least one of the first and second electrodes, the lateral surface facing away from the ferroelectric layer.
7. The ferroelectric memory cell of claim 1 , wherein:
a doping concentration of the one of the pair of edge doped portions extends from the exposed surface of the one of the pair of edge doped portions in contact with the healing layer to the undoped portion of the ferroelectric layer.
8. A ferroelectric memory cell, comprising:
a first electrode;
a second electrode;
a ferroelectric layer disposed between the first electrode and the second electrode, and comprising a pair of edge doped portions and an undoped portion between the pair of edge doped portions in a cross-sectional view;
the ferroelectric layer comprises a pair of recessed portions;
a healing layer, wherein the pair of edge doped potions of the ferroelectric layer and side walls of at least one of the first and second electrodes extending in a first directions are covered by the healing layer, wherein the first direction is perpendicular to an exposed surface of one of the pair of edge doped portions in contact with the healing layer, and a length of the ferroelectric layer extending in the first direction is less than that of each of the first and second electrodes, wherein the healing layer comprises a first material and a plurality of dopants of a second material, the second material being different from the first material and
a block layer covering the healing layer.
9. The ferroelectric memory cell of claim 8 , wherein:
the one of the pair of edge doped portions comprises at least one of hafnium (Hf), zirconium (Zr), titanium (Ti), aluminum (Al), silicon (Si), hydrogen (H), oxygen (O), vanadium (V), niobium (Nb), tantalum (Ta), yttrium (Y), or lanthanum (La).
10. The ferroelectric memory cell of claim 8 , wherein:
the one of the pair of edge doped portions extends laterally from the exposed surface into a depth in the ferroelectric layer, the depth being along the first direction; and
the depth has a range of about 5 Å to about 10 nm.
11. The ferroelectric memory cell of claim 8 , wherein
the one of the pair of edge doped portions comprises the pair of recessed portions.
12. The ferroelectric memory cell of claim 8 , wherein the block layer comprises at least one of silicon nitride, silicon oxynitride, or aluminum oxide, and has a thickness of about 15 Å to about 500 Å.