Method of fabricating memory devices using pocket integration
A pocket integration for high density memory and logic applications and methods of fabrication are described. While various embodiments are described with reference to FeRAM, capacitive structures formed herein can be used for any application where a capacitor is desired. For example, the capacitive structure can be used for fabricating ferroelectric based or paraelectric based majority gate, minority gate, and/or threshold gate.
1. A method of fabricating a device structure, the method comprising:
forming a first conductive interconnect in a dielectric in a memory region and a second conductive interconnect in a logic region;
depositing an etch stop layer on the dielectric and on the first conductive interconnect and on the second conductive interconnect;
etching and removing the etch stop layer from the memory region but not from the logic region;
depositing a material layer stack including a non-linear polar material on the first conductive interconnect, on the dielectric, on a sidewall of the etch stop layer, at an interface between the memory region and the logic region and on the etch stop layer;
forming a memory device by etching the material layer stack, wherein the etching forms the memory device directly on at least a portion of the first conductive interconnect;
depositing an encapsulation layer on the memory device, including on a top surface and on at least a sidewall of the memory device;
forming a mask on the encapsulation layer above the memory device;
using the mask to etch portions of the encapsulation layer;
blanket depositing a dielectric layer;
forming a first opening in the dielectric layer, the first opening exposing the second conductive interconnect in the logic region;
forming an interconnect via in the first opening and a metal line on the interconnect via by depositing a conductive material in the first opening;
forming a second opening in the dielectric layer and in the encapsulation layer, the second opening exposing the memory device; and
forming a via electrode in the second opening by depositing the conductive material in the second opening.
2. The method of claim 1 , wherein the non-linear polar material comprises one of:
bismuth ferrite (BFO) or BFO with a first doping material, wherein the first doping material is one of lanthanum or elements from lanthanide series of periodic table;
lead zirconium titanate (PZT) or PZT with a second doping material, wherein the second doping material is one of La or Nb;
a relaxor ferroelectric material which includes one of: lead magnesium niobate (PMN), lead magnesium niobate-lead titanate (PMN-PT), lead lanthanum zirconate titanate (PLZT), lead scandium niobate (PSN), barium titanium-bismuth zinc niobium tantalum (BT-BZNT), or barium titanium-barium strontium titanium (BT-BST);
a perovskite material which includes one of: BaTiO 3 , PbTiO 3 , KNbO 3 , or NaTaO 3 ; a hexagonal ferroelectric which includes one of: YMnO 3 , or LuFeO 3 ; hexagonal ferroelectrics of a type h-RMnO 3 , where R is a rare earth element which includes one of: cerium (Ce), dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium (Tm), ytterbium (Yb), or yttrium (Y);
hafnium (Hf), zirconium (Zr), aluminum (Al), silicon (Si), their oxides, or their alloyed oxides;
hafnium oxides as Hf (1-x) E (x) O (y) , where E can be Al, Ca, Ce, Dy, Er, Gd, Ge, La, Sc, Si, Sr, Sn, Zr, or Y, where x and y are first and second fractions, respectively;
Al (1-x) Sc (x) N, Ga (1-x) Sc (x) N, Al (1-x) Y (x) N or Al (1-x-y) Mg (x) Nb (y) N, where x and y are third and fourth fractions, respectively;
doped HfO 2 ;
niobate type compounds LiNbO 3 , LiTaO 3 , lithium iron tantalum oxy fluoride, barium strontium niobate, sodium barium niobate, or potassium strontium niobate;
an improper ferroelectric material which includes one of: [PTO/STO] n or [LAO/STO] n , where ‘n’ is between 1 and 100; or
SrTiO 3 , Ba (x) Sr (y) TiO 3 , HfZrO 2 , Hf—Si—O, La-substituted PbTiO 3 , or a PMN-PT based relaxor ferroelectric; and
wherein etching the material layer stack forms a spacer of the material layer stack adjacent to the sidewall of the etch stop layer.
3. The method of claim 2 , wherein etching the material layer stack to form the memory device further comprises:
forming the memory device on a portion of the dielectric; and
etching and recessing the dielectric adjacent to the memory device, wherein recessing forms a dielectric surface below a lowermost surface of the memory device, and a dielectric sidewall that is substantially aligned with the sidewall of the memory device.
4. The method of claim 3 , wherein forming the encapsulation layer further comprises depositing the encapsulation layer on the dielectric sidewall and on the dielectric surface.
5. The method of claim 2 , wherein depositing the encapsulation layer further comprises depositing on the spacer of the material layer stack.
6. The method of claim 5 , wherein forming the mask further comprises forming the mask on the encapsulation layer deposited on the spacer of the material layer stack, and wherein patterning the encapsulation layer further comprises etching and removing the encapsulation layer from above the etch stop layer and leaving a third portion of the encapsulation layer on the spacer of the material layer stack and on a surface of the dielectric.
7. The method of claim 6 , wherein the memory device is a first memory device, wherein the via electrode is a first via electrode, wherein etching the material layer stack forms a second memory device above a third conductive interconnect, the third conductive interconnect laterally formed in the dielectric on a plane that is laterally distant from the plane of the first conductive interconnect, and wherein the method further comprises:
forming a second via electrode on the second memory device; and
forming a plate electrode extending from above first via electrode to above the second via electrode.
8. The method of claim 1 , wherein the mask comprises a first lateral thickness that is at least equal to a second lateral thickness of the memory device and two times a third lateral thickness of the encapsulation layer.
9. The method of claim 8 , wherein the first lateral thickness is greater than the second lateral thickness and two times the third lateral thickness, and wherein etching the encapsulation layer further comprises:
forming a patterned encapsulation layer comprising:
a first portion on the memory device;
a second portion adjacent to sidewalls of the memory device, the second portion comprising a fourth lateral thickness; and
a lateral extension adjacent to the second portion, the lateral extension on a third portion of the dielectric.
10. The method of claim 8 , wherein the first lateral thickness is substantially equal to the second lateral thickness and two times the third lateral thickness, and wherein etching the encapsulation layer adjacent to the memory device comprises forming a patterned encapsulation layer having a substantially uniform lateral thickness and an outermost encapsulation layer sidewall.
11. The method of claim 1 , wherein the method of forming the first opening further comprises:
performing a plasma etch process to form a hanging trench above the second conductive interconnect;
forming a via mask within the hanging trench, the via mask comprising a third opening; and
forming a fourth opening by etching the dielectric layer exposed by the third opening and by etching the etch stop layer after etching the dielectric layer, the etching exposing the second conductive interconnect.
12. The method of claim 11 , wherein forming the metal line and the interconnect via comprises:
simultaneously depositing the conductive material in the hanging trench and in the fourth opening and on the dielectric layer; and
planarizing the conductive material from above the dielectric layer to isolate the conductive material in the hanging trench and in the fourth opening.
13. A method of fabricating a device structure, the method comprising:
forming a first conductive interconnect in a dielectric in a memory region and a second conductive interconnect in a logic region;
depositing an etch stop layer on the dielectric and on the first conductive interconnect and on the second conductive interconnect;
etching and removing the etch stop layer from the memory region but not from the logic region;
depositing a material layer stack including ferroelectric or paraelectric material on the first conductive interconnect, on the dielectric, and on the etch stop layer;
forming a memory device by etching the material layer stack, wherein the etching forms the memory device directly on at least a portion of the first conductive interconnect;
depositing an encapsulation layer on the memory device, including on a top surface and on at least a sidewall of the memory device;
forming a first mask on the encapsulation layer above the memory device;
using the first mask to etch portions of the encapsulation layer;
blanket depositing a dielectric layer;
forming a hanging trench in the dielectric layer over the second conductive interconnect by etching the dielectric layer and simultaneously forming a first opening to expose the memory device, wherein the first opening is formed by etching the dielectric layer and the encapsulation layer above the memory device;
forming a second mask within the hanging trench and in the first opening, the second mask comprising a second opening within the hanging trench;
forming a third opening by etching the dielectric layer exposed by the second opening and by etching the etch stop layer after etching the dielectric layer, the etching exposing the second conductive interconnect;
removing the second mask and simultaneously depositing a conductive material in the first opening, in the third opening and in the hanging trench and on the dielectric layer; and
planarizing the conductive material to simultaneously form a via electrode on the memory device, a via interconnect in the third opening and a metal line in the hanging trench.
14. The method of claim 13 , wherein etching comprises utilizing a plasma etch process and forming the hanging trench and the first opening further comprises:
halting the plasma etch process after the encapsulation layer is exposed in the memory region; and
continuing the plasma etch process to remove the encapsulation layer from above the memory device.
15. The method of claim 13 , wherein etching the encapsulation layer to form the first opening recesses the hanging trench below a level of an uppermost surface of the memory device.
16. A method of fabricating a device structure, the method comprising:
forming a first trench interconnect in a dielectric in a memory region and a second trench interconnect in a logic region;
depositing an etch stop layer on the dielectric and on the first trench interconnect and on the second trench interconnect;
etching to remove the etch stop layer from the memory region but not from the logic region;
depositing a material layer stack including ferroelectric or paraelectric material on the first trench interconnect, on the dielectric, and on the etch stop layer;
forming a memory device by etching the material layer stack, wherein the etching forms the memory device directly above the first trench interconnect;
depositing an encapsulation layer on the memory device, including on a top surface and on at least a sidewall of the memory device;
forming a mask on the encapsulation layer above the memory device;
using the mask to etch portions of the encapsulation layer;
blanket depositing a dielectric layer;
forming a first opening in the dielectric layer and in the encapsulation layer above the memory device and simultaneously forming a second opening in the dielectric layer above the second trench interconnect;
completely masking the first opening and partially masking the second opening to form a via opening within the second opening;
etching the dielectric layer through the via opening and exposing the second trench interconnect; and
forming a via electrode in the first opening, a via structure in the via opening and a metal line in the second opening by depositing a conductive material in the first opening, in the via opening and in the second opening.
17. The method of claim 16 , wherein the mask covers a portion of the encapsulation layer that is above the dielectric adjacent to the first trench interconnect.
18. The method of claim 16 , wherein the memory device is a first memory device, wherein the first memory device is above a first portion of the first trench interconnect, and wherein etching the material layer stack forms a second memory device above a second portion of the first trench interconnect, the second portion laterally distant from the first portion.
19. The method of claim 18 , wherein using the mask to etch the portions of the encapsulation layer forms the encapsulation layer around sidewalls of the first memory device and the second memory device, and wherein the encapsulation layer extends parallel to the first trench interconnect.