阅读说明：本技术 对于具有垂直磁异向性的磁性装置应用在高温退火后保持矫顽磁场 (Application to magnetic devices with perpendicular magnetic anisotropy for maintaining coercive field after high temperature annealing ) 是由 刘焕龙 李元仁 朱健 真杰诺 路克·汤马斯 王柏刚 童儒颖 裘地·玛丽·艾维塔 于 2018-03-06 设计创作，主要内容包括：公开一种具有垂直磁异向性的磁穿隧接面(PMA MTJ),其中自由层(14)与隧道位障(13)具有界面(20)以及与氧化物层(15)具有第二界面(21)。晶格匹配层(16-1)邻接氧化物层相对于自由层的相反侧,并且包含Co<Sub>x</Sub>FeyNi<Sub>z</Sub>L<Sub>w</Sub>M<Sub>v</Sub>或Co<Sub>x</Sub>FeyNi<Sub>z</Sub>L<Sub>w</Sub>,其中L是B、Zr、Nb、Hf、Mo、Cu、Cr、Mg、Ta、Ti、Au、Ag或P之一,且M是Mo、Mg、Ta、Cr、W或V之一,(x+y+z+w+v)＝100原子百分比,x+y>0,且v和w各自>0。晶格匹配层在约400℃的退火期间成长体心立方结构,借此促进体心立方结构在氧化物层中的成长。结果,增强并维持自由层垂直磁异向性以产生改善的热稳定性。(A magnetic tunneling junction (PMA MTJ) with perpendicular magnetic anisotropy is disclosed, in which a free layer (14) has an interface (20) with a tunnel barrier (13) and a second interface (21) with an oxide layer (15). A lattice matching layer (16-1) is adjacent to the opposite side of the oxide layer from the free layer and comprises Co x FeyNi z L w M v Or Co x FeyNi z L w Wherein L is for B, Zr, Nb, Hf, Mo, Cu, Cr, Mg, Ta, Ti, Au, Ag or P, and M is for Mo, Mg, Ta, Cr, W or V, (x + y + z +w + v) 100 atomic percent, x + y>0, and v and w are each>0. The lattice matching layer grows a body centered cubic structure during an anneal at about 400 ℃, thereby promoting growth of the body centered cubic structure in the oxide layer. As a result, the perpendicular magnetic anisotropy of the free layer is enhanced and maintained to result in improved thermal stability.)

1, magnetic memory elements formed between a th electrode and a second electrode, comprising:

(a) tunnel barrier layer formed between reference layer and free layer;

(b) the free layer having a surface, the free layer forming a interface with the tunnel barrier layer, thereby facilitating Perpendicular Magnetic Anisotropy (PMA) in the free layer;

(c) an oxide layer forming a second interface with the free layer at a second surface of the free layer opposite the free layer relative to the tunnel barrier layer, and wherein the oxide layer and the free layer both have a body-centered cubic (BCC) structure that enhances perpendicular magnetic anisotropy in the free layer, and

(d) lattice matching layer adjacent to the opposite side of the oxide layer relative to the second interface, wherein the lattice matching layer comprises a magnetic material that is Co_XFe_YNi_ZL_WAn alloy wherein L is a nonmagnetic element, (x + y + z + w) ═ 100 atomic percent, x + y>0, and w>0, and wherein the body centered cubic structure of the th lattice matching layer facilitates growth of the body centered cubic structure in the oxide layer.

2. The magnetic memory element of claim 1 wherein L is of B, Zr, Nb, Hf, Mo, Cu, Cr, Mg, Ta, Ti, Au, Ag or P.

3. The magnetic memory element of claim 1 further comprising a second lattice matching layer, the second lattice matching layer being a single layer or a multilayer structure, abutting an opposite side of the th lattice matching layer relative to the oxide layer, and wherein the second lattice matching layer is or more of Mo, Mg, Ta, Cr, W, Ru, or V.

4. The magnetic memory element of claim 1 further comprising a second lattice matching layer, the second lattice matching layer being Co_XFe_YNi_ZL_WM_VA layer, wherein L is a nonmagnetic element, (x + y + z + W + V) ═ 100 atomic percent, M is of Mo, Mg, Ta, Cr, W, Ru, or V, x + y>0, v and w are each>0, and wherein the Co_XFe_YNi_ZL_WM_VLayer adjacent to the Co_XFe_YNi_ZL_WThe opposite side of the alloy layer relative to the oxide layer.

5. The magnetic memory element of claim 4 further comprising a third lattice matching layer, the third lattice matching layer being an M layer formed on the Co_XFe_YNi_ZL_WM_VLayer opposite to the Co_XFe_YNi_ZL_WOn the opposite side of the layer.

6. The magnetic memory element of claim 3 wherein the Co_XFe_YNi_ZL_WThe alloy layer and the M layer each have a thickness of about 2 to 10 angstroms.

7. The magnetic memory element of claim 3 further comprising a seed layer and a hard mask to provide a seed layer/reference layer/tunnel barrier/free layer/oxide layer/ a lattice matching layer/second lattice matching layer/hard mask stack in a bottom spin valve configuration, wherein the seed layer contacts the electrode and the hard mask contacts a bottom surface of the second electrode.

8. The magnetic memory element of claim 5 further comprising a seed layer and a hard mask to provide a seed layer/reference layer/tunnel barrier/free layer/oxide layer/ a lattice matching layer/second lattice matching layer/third lattice matching layer/hard mask stack in a bottom spin valve configuration, wherein the seed layer contacts the electrode and the hard mask contacts a bottom surface of the second electrode.

9. The magnetic memory element of claim 1 wherein the oxide layer is MgTaOx, MgO, SiOx, SrTiOx, BaTiOx, CaTiOx, LaAlOx, MnOx, VOx, Al₂O₃ of TiOx, BOx and HfOx, or or a laminate of a plurality of the aforementioned oxides.

10. The magnetic memory element of claim 3 further comprising a seed layer and a hard mask to provide a seed layer/second lattice matching layer/ a lattice matching layer/oxide layer/free layer/tunnel barrier/reference layer/hard mask stack in a top spin valve configuration, wherein the seed layer contacts the electrode and the hard mask contacts a bottom surface of the second electrode.

11. The magnetic memory element of claim 5 further comprising a seed layer and a hard mask to provide a seed layer/third lattice matching layer/second lattice matching layer/ a lattice matching layer/oxide layer/free layer/tunnel barrier/reference layer/hard mask stack in a top spin valve configuration, wherein the seed layer contacts the electrode and the hard mask contacts a bottom surface of the second electrode.

12. The magnetic memory element of claim 1 wherein the oxide layer is about 2 to 20 angstroms thick.

13. The magnetic memory element of claim 1 wherein the th electrode is a bottom electrode in a Magnetoresistive Random Access Memory (MRAM) device or a spin torque magnetoresistive random access memory (automtron), or the th electrode is a main magnetic pole layer in a Spin Torque Oscillator (STO) device.

14, magnetic memory elements formed between a th electrode and a second electrode, comprising:

(a) tunnel barrier layer formed between reference layer and free layer;

(b) the free layer having a surface, the free layer forming a interface with the tunnel barrier layer, thereby facilitating Perpendicular Magnetic Anisotropy (PMA) in the free layer;

(c) an oxide layer forming a second interface with the free layer at a second surface of the free layer opposite the free layer relative to the tunnel barrier layer, and wherein the oxide layer and the free layer both have a body-centered cubic (BCC) structure that enhances perpendicular magnetic anisotropy in the free layer, and

(d) a lattice matching layer adjacent to the opposite side of the oxide layer relative to the second interface, wherein the lattice matching layer is an oxide or nitride of Ru, Ta, Ti or Si, or has Co_XFe_YNi_ZL_WM_VWherein L is a non-magnetic metal, M is of Mo, Mg, Ta, Cr, W, Ru or V, (x + y + z + W + V) ═ 100 atomic percent, x + y>0, and v andw are each>0, and wherein the body centered cubic structure of the th lattice matching layer facilitates growth of the body centered cubic structure in the oxide layer.

15. The magnetic memory element of claim 14 wherein L is of B, Zr, Nb, Hf, Mo, Cu, Cr, Mg, Ta, Ti, Au, Ag or P.

16. The magnetic memory element of claim 14 further comprising a second lattice matching layer, the second lattice matching layer being a single layer or a multilayer structure, abutting an opposite side of the th lattice matching layer relative to the oxide layer, and wherein the second lattice matching layer is single layer and multilayer structures comprising or more of Mo, Mg, Ta, Cr, W, Ru, or V.

17. The magnetic memory element of claim 14 wherein the oxide layer is MgTaOx, MgO, SiOx, SrTiOx, BaTiOx, CaTiOx, LaAlOx, MnOx, VOx, Al₂O₃ of TiOx, BOx and HfO x, or or a laminate of a plurality of the aforementioned oxides.

18. The magnetic memory element of claim 16 wherein the th lattice matching layer is the Co_XFe_YNi_ZL_WM_VLayer, and the second lattice matching layer and the Co_XFe_YNi_ZL_WM_VThe layers each have a thickness of about 2 to 10 angstroms.

19. The magnetic memory element of claim 16 further comprising a third lattice matching layer, the third lattice matching layer having Co_XFe_YNi_ZL_WComposition of, wherein w>0 and x + y>0 formed between the th lattice matching layer and the second lattice matching layer, and wherein the th lattice matching layer is an oxide or nitride of Ru, Ta, Ti, or Si.

20. The magnetic memory element of claim 19 wherein the th lattice matching layer is conductive and the combined thickness of the th, second and third lattice matching layers is about 2 to 100 angstroms.

21. The magnetic memory element of claim 14 further comprising a seed layer and a hard mask to provide a seed layer/reference layer/tunnel barrier/free layer/oxide layer/ a lattice matching layer/hard mask stack in a bottom spin valve configuration, wherein the seed layer contacts the electrode and the hard mask contacts a bottom surface of the second electrode.

22. The magnetic memory element of claim 16 further comprising a seed layer and a hard mask to provide a seed layer/reference layer/tunnel barrier/free layer/oxide layer/ a lattice matching layer/second lattice matching layer/hard mask stack in a bottom spin valve configuration, wherein the seed layer contacts the electrode and the hard mask contacts a bottom surface of the second electrode.

23. The magnetic memory element of claim 14 further comprising a seed layer and a hard mask to provide a seed layer/ a lattice matching layer/an oxide layer/a free layer/a tunnel barrier/a reference layer/a hard mask stack in a top spin valve configuration, wherein the seed layer contacts the electrode and the hard mask contacts a bottom surface of the second electrode.

24. The magnetic memory element of claim 16 further comprising a seed layer and a hard mask to provide a seed layer/second lattice matching layer/ a lattice matching layer/oxide layer/free layer/tunnel barrier/reference layer/hard mask stack in a top spin valve configuration, wherein the seed layer contacts the electrode and the hard mask contacts a bottom surface of the second electrode.

25, a method of forming a magnetic memory element having a stack comprising:

(a) sequentially depositing a reference layer, a tunnel barrier, and a free layer on an substrate, wherein the free layer forms a th interface with the tunnel barrier, thereby inducing or enhancing Perpendicular Magnetic Anisotropy (PMA) in the free layer;

(b) forming an oxide layer on a top surface of the free layer to form a second interface that induces or enhances perpendicular magnetic anisotropy in the free layer;

(c) forming a lattice matching layer on the oxide layer, wherein the lattice matching layer is amorphous when deposited and comprises Co_XFe_YNi_ZL_WM_VA layer, an oxide or nitride of Ru, Ta, Ti and Si, or a film layer formed of a magnetic material which is Co_XFe_YNi_ZL_WAn alloy wherein L is a non-magnetic element, M is of Mo, Mg, Ta, Cr, W, Ru or V, (x + y + z + W + V) ═ 100 atomic percent, x + y>0, and v and w are each>0；

(d) Depositing a hard mask as the uppermost layer in the stack, and

(e) annealing the stack at a temperature near 400 ℃ to grow a body centered cubic structure in the th lattice matching layer to promote growth of the body centered cubic structure in the oxide layer.

26. The method of claim 25 wherein L is of B, Zr, Nb, Hf, Mo, Cu, Cr, Mg, Ta, Ti, Au, Ag, or P.

27. The method of claim 25, further comprising depositing a second lattice matching layer on said th lattice matching layer prior to forming said hard mask, said second lattice matching layer being of single or multilayer structure and comprising or more M elements selected from Mo, Mg, Ta, Cr, W, Ru and V.

28. The method of claim 25, wherein the oxide layer is MgTaOx, MgO, SiOx, SrTiOx, BaTiOx, CaTiOx, LaAlOx, MnOx, VOx, Al₂O₃ of TiOx, BOx and HfOx, or or a laminate of a plurality of the aforementioned oxides.

29. The method of claim 27, wherein depositing the second lattice matching layer on the th lattice matching layer forms Co_XFe_YNi_ZL_WM_VOr formed with Co, or_XFe_YNi_ZL_W/M or Co_XFe_YNi_ZL_WM_VA bilayer stack in a/M configuration, wherein the M element layer contacts the hardmask.

30. The method of claim 27, wherein Co consists of_XFe_YNi_ZL_WDepositing the second lattice matching layer on the th lattice matching layer_XFe_YNi_ZL_W/Co_XFe_YNi_ZL_WM_VA three layer stack in a/M configuration, wherein the M element layer contacts the hard mask.

31. The method of claim 25, wherein the substrate is an seed layer or th electrode, and the th electrode is a bottom electrode in a Magnetoresistive Random Access Memory (MRAM) device or a spin torque magnetoresistive random access memory (spin torque MRAM) device, or the th electrode is a main magnetic pole layer in a Spin Torque Oscillator (STO) device.

32. The method of claim 25, wherein said th lattice matching layer is an oxide or nitride of Ru, Ta, Ti, or Si, and further comprising depositing Co-containing material on said th lattice matching layer prior to forming said hard mask_XFe_YNi_ZL_W second lattice matching layer of alloy composition, then third lattice matching layer of or more M elements on the second lattice matching layer is deposited.

33, a method of forming a magnetic memory element having a stack comprising:

(a) depositing a th lattice matching layer on a substrate, the th lattice matching layer being a single layer or a multilayer structure and comprising or more M elements selected from Mo, Mg, Ta, Cr, W, Ru, and V;

(b) depositing a second lattice matching layer on the th lattice matching layer, wherein the second lattice matching layer is amorphous when deposited and comprises a material having Co_XFe_YNi_ZL_WA magnetic material of composition wherein L is a nonmagnetic element, (x + y + z + w) ═ 100 atomic percent, x + y>0, and w>0；

(c) Forming an oxide layer on the second lattice matching layer;

(d) depositing a free layer contacting a top surface of the oxide layer to form a th interface, the th interface inducing or enhancing Perpendicular Magnetic Anisotropy (PMA) in the free layer;

(e) sequentially forming a tunnel barrier, a reference layer and a hard mask, wherein the tunnel barrier contacts the top surface of the free layer to form a second interface that induces or enhances perpendicular magnetic anisotropy in the free layer, and

(f) the stack is annealed at a temperature of about 400 ℃ such that the second lattice matching layer develops a body centered cubic structure to match the body centered cubic structure developed in the oxide layer.

34. The method of claim 33 wherein L is of B, Zr, Nb, Hf, Mo, Cu, Cr, Mg, Ta, Ti, Au, Ag, or P.

35. The method of claim 33, wherein the oxide layer is MgTaOx, MgO, SiOx, SrTiOx, BaTiOx, CaTiOx, LaAlOx, MnOx, VOx, Al₂O₃ of TiOx, BOx and HfOx, or or a laminate of a plurality of the aforementioned oxides.

36. The method of claim 33, wherein depositing the second lattice matching layer on the th lattice matching layer forms a layer having Co_XFe_YNi_ZL_WM_V mono-lattice matching layer of composition, wherein (x + y + z + w + v) ═ 100 atomic percent, x + y>0, and v and w are each>0, and wherein the single crystal lattice matching layer abuts the oxide layer and grows a body-centered cubic structure during annealing of the stack, thereby promoting growth of the body-centered cubic structure in the oxide layer.

37. The method of claim 33, wherein depositing the second lattice matching layer on the th lattice matching layer forms a layer with M/Co_XFe_YNi_ZL_WOr M/Co_XFe_YNi_ZL_WM_VA bilayer stack configured wherein the Co_XFe_YNi_ZL_WM_VOr Co_XFe_YNi_ZL_WContacting the oxide layer and the Co being present during annealing of the stack_XFe_YNi_ZL_WM_VOr Co_XFe_YNi_ZL_WA layer grows a body centered cubic structure to promote growth of the body centered cubic structure in the oxide layer.

38. The method of claim 33, wherein depositing the second lattice matching layer on the th lattice matching layer forms a layer with M/Co_XFe_YNi_ZL_WM_V/Co_XFe_YNi_ZL_WConfigured three-layer stack of Co_XFe_YNi_ZL_WContacting the oxide layer and the Co being present during annealing of the stack_XFe_YNi_ZL_WA layer grows a body centered cubic structure to promote growth of the body centered cubic structure in the oxide layer.

39. The method of claim 33, wherein the substrate is an seed layer or electrode and the electrode is a bottom electrode in a Magnetoresistive Random Access Memory (MRAM) device or a spin torque magnetoresistive random access memory (spin torque MRAM) device or the electrode is a main magnetic pole layer in a Spin Torque Oscillator (STO) device.

40. The method of claim 33, further comprising depositing a third lattice matching layer on the second lattice matching layer before depositing the oxide layer, wherein the third lattice matching layer is an oxide or nitride of Ru, Ta, Ti, or Si.

Technical Field

Embodiments of the present invention relate to magnetic devices having Magnetic Tunnel Junctions (MTJs) with Perpendicular Magnetic Anisotropy (PMA), and in particular to the insertion of a lattice-matching layer between the capping layer and the top electrode to maintain coercivity (Hc) in the MTJ stack during subsequent annealing or semiconductor processing at high temperatures of about 400 ℃.

Background

Magnetoresistive Random Access Memory (MRAM) has a read function based on the Tunneling Magnetoresistive (TMR) effect in a mtj stack, in which a tunnel barrier (tunnel barrier) is formed between a free layer and a reference layer. The free layer acts as a sense layer by switching its magnetic moment direction in response to an external field (medium field), while the reference layer has a fixed magnetic moment.

Magnetoresistive random access memory devices including mtj elements, in which or both the free layer and the reference layer have perpendicular magnetic anisotropy, are advantageous over magnetoresistive random access memory devices employing in-plane anisotropy because the former has the advantage of lower write current for the same thermal stability and better scalability (scalability). in a mtj with perpendicular magnetic anisotropy, the free layer storing information for a memory bit has two preferred magnetization directions, which are perpendicular to the physical plane of the free layer. without external influences, the magnetization direction of the free layer would align with of the two preferred directions, i.e., up or down, representing information "1" or "0" in a binary system.

However, the physical shape of a free layer with a lateral dimension greater than ten times the thickness tends to induce in-plane anisotropy, where the magnetization direction of the Free Layer (FL) is in the plane of the free layer, and furthermore, as the free layer thickness (volume) increases, the majority of the free layer moves away from the free layer/tunnel barrier interface where the perpendicular magnetic anisotropy occurs, thus, the step is advanced to reduce the perpendicular magnetic anisotropy, until the free layer thickness is sufficiently large, the free layer anisotropy is not entirely "in-plane".

Thermal stability is a function of the vertical anisotropy field, as shown in equation (1), where k_BIs the Boltzmann constant, T is the temperature, M_SIs the saturation magnetization, and

and V is the out-of-plane (out-of-plane) anisotropy field and volume of the free layer, respectively:

(1)

the perpendicular anisotropy field of the magnetic layer is expressed in formula (2) as:

(2)

where d is the thickness of the free layer, H_k,χ,⊥Is a crystal anisotropy field in the vertical direction, and

is the surface vertical anisotropy of the top and bottom surfaces of the free layer. Shape anisotropy field in the wording (-4 π M_S) And (4) showing.

To increase the value byThe capping layer typically contacts the uppermost magnetic-tunneling interface layer, referred to as a hard mask, which in turn is connected to a top electrode and via a top electrode array to complementary metal-oxide-semiconductor (CMOS) elements in the memory chip.

generally recognizes that the perpendicular magnetic anisotropy between adjacent CoFeB and MgO layers can be optimized when both layers have a matched body-centered cubic (BCC) structure, however, the perpendicular magnetic anisotropy is easily attenuated by diffusion of metal from the hard mask into the capping layer, thereby interrupting the body-centered cubic formation process in the capping layer.

Disclosure of Invention

It is an object of an embodiment of the invention to provide a mtj stack in magnetic devices in which the free layer has perpendicular magnetic anisotropy and coercivity (Hc) that is preserved after high temperature processing including annealing at temperatures up to 400 c for multiple hours.

It is a second object of embodiments of the present invention to provide a mtj stack according to object such that other characteristics, including the tunneling magnetoresistance ratio and the resistance area product (RA) value, are maintained at acceptable levels.

According to embodiments of the present invention, these objects are achieved by configuring a magnetic tunnel junction with perpendicular magnetic anisotropy (PMA MTJ) with a bottom spin valve (spin valve) structure having a Reference Layer (RL)/tunnel barrier/Free Layer (FL)/oxide layer stack to include a lattice matching layer between the oxide layer (cap layer) and an overlying hard mask.

According to embodiments, the lattice matching layer is a bilayer, where the st layer is made of, for example, Co_XFe_YNi_ZL_WWherein L is of B, Zr, Nb, Hf, Mo, Cu, Cr, Mg, Ta, Ti, Au, Ag or P, and (x + y + z + w) ═ 100 atomic percent, x + y>0, and w>0。Co_XFe_YNi_ZL_WContacting an oxide layer in a bottom spin valve configurationThe second layer is preferably of Mo, Ta, Mg, Cr, V, Ru, or W the second layer is effective to eliminate magnetic interaction between the th layer and the free layer, and preferably remains amorphous at a temperature near 400 ℃, thereby blocking migration of the nonmagnetic metal from the hard mask, top electrode, or bottom electrode to Co_XFe_YNi_ZL_WIn the layer and avoid damage to Co_XFe_YNi_ZL_WA body-centered cubic structure formed in the layer.

In another embodiment, the lattice matching layer may be a single layer of an alloy that is the material of the and second layers_XFe_YNi_ZL_WDuring the deposition of the layer, the latter can be re-sputtered (resputtered) to form a layer consisting of Co_XFe_YNi_ZL_WM_VA film is shown where w and v are both greater than 0 in which case the lower concentration of M may be formed closer to the cap layer than the upper portion of the lattice matched layer in yet another embodiment, the deposition of M material is controlled to the point where only the upper portion of the th layer is re-sputtered_XFe_YNi_ZL_W/Co_XFe_YNi_ZL_WM_Va/M three-layer stack.

Embodiments of the invention also include embodiments in which the lattice matching layer has a bi-or tri-layer configuration in which the th layer is an oxide or nitride of Ru, Ta, Ti, or Si, the th layer has a th surface adjacent to the oxide layer and a second surface opposite the th surface, the second surface contacting the second layer, the second layer comprising or more M elements, the M elements being Mo, Ta, Mg, Cr, V, Ru, and W, or contacting the second layer having Co_XFe_YNi_ZL_WA stack of/M compositions.

In a perpendicular magnetic anisotropy tunneling junction with a top spin valve configuration, an optional seed layer is formed on the bottom electrode. When the seed layer is omitted, the second layer comprising the metal or alloy M may act as a seed layer on the bottom electrode. Furthermore, a plurality of M materials may be deposited such that the second layer is, for example, a bilayer or a trilayer. Then will be made of Co_XFe_YNi_ZL_WThe formed th layer is deposited on the second layer to provide M/Co for the lattice matching layer_XFe_YNi_ZL_W embodiments, a quantitative second layer is re-sputtered to produce M/Co for the lattice matching layer_XFe_YNi_ZL_WM/Co_XFe_YNi_ZL_WThree layers configuration, or the M layer can be re-sputtered completely and then Co_XFe_YNi_ZL_WAlloy Co-deposition to produce alloy with Co_XFe_YNi_ZL_WM_VA single lattice matching layer of composition.

The free layer may be a single layer formed of Co, Fe, or alloys thereof, with or more elements contained in Ni and B in an alternative embodiment, the free layer has two magnetic layers FL1 and FL2 separated by an antiferromagnetic (antiferromagnetic) coupling layer, such as Ru, or by a nonmagnetic insertion layer of Ta or similar material as the moment diluting layer (moment diluting layer.) the reference layer abuts the surface of the tunnel barrier opposite the free layer in the preferred embodiment, the reference layer has a synthetic antiparallel (SyAP) configuration in which two magnetic layers called AP1 and AP2 are antiferromagnetically coupled, such as via a Ru layer.

After all the layers in the mtj are placed, conventional processes are applied to convert the mtj stack into multiple mtj devices. In a subsequent step, an annealing process including a temperature of about 400 ℃ is performed to transform the amorphous characteristics of the free layer, the tunnel barrier and the oxide layer into a body-centered cubic crystal structure, thereby enhancing the perpendicular magnetic anisotropy of the free layer.

Drawings

FIG. 1 is a cross-sectional view of an embodiment of the MTJ with bottom spin valve design where a lattice matching layer with a double layer structure is formed between the cap layer and the top electrode.

FIG. 2 is a cross-sectional view of a perpendicular magnetic anisotropy tunneling junction with a bottom spin valve design according to a second embodiment of the invention, wherein a lattice-matched monolayer is formed between the cap layer and the top electrode.

FIG. 3 is a cross-sectional view of a vertical magnetic anisotropy tunneling junction with a bottom spin valve design according to a third embodiment of the invention, wherein a lattice matching layer with a double-layer structure is formed between a cap layer and a top electrode.

FIGS. 4 and 5 are schematic cross-sectional views of a vertical magnetic anisotropy tunneling junction with a bottom spin valve design according to a fourth and fifth embodiment of the invention, wherein a lattice matching layer with a three-layer stack is formed between the cap layer and the top electrode.

FIG. 6 is a cross-sectional view of a vertical magnetic anisotropy tunneling junction with a top spin valve design according to a sixth embodiment of the invention, wherein a lattice matching layer with a three-layer structure is formed between a Hk enhancing layer and a Bottom Electrode (BE).

FIG. 7 is a cross-sectional view of a vertical magnetic anisotropy tunneling junction with a top spin valve design according to a seventh embodiment of the invention, wherein a lattice matching layer with a double-layer structure is formed between a Hk enhancing layer and a bottom electrode.

FIG. 8 is a cross-sectional view of a perpendicular magnetic anisotropy tunneling junction with a top spin valve design according to an eighth embodiment of the invention, wherein a lattice-matched monolayer is formed between a Hk enhancing layer and a bottom electrode.

FIG. 9 is a cross-sectional view of a ninth embodiment of a perpendicular magnetic anisotropic tunneling junction (top spin valve design) according to the present invention, wherein a lattice matching layer with a double layer stack is formed between the Hk enhancing layer and the bottom electrode.

FIG. 10 is a cross-sectional view of a top spin valve perpendicular magnetic anisotropy tunneling junction according to a tenth embodiment of the disclosure, wherein a lattice matching layer with a three-layer structure is formed between a Hk enhancing layer and a bottom electrode.

FIGS. 11-14 depict cross-sectional schematic diagrams of a series of steps during fabrication of a perpendicular magnetic anisotropy tunnel junction with a bottom spin valve design, according to of embodiments of the invention.

Detailed Description

Embodiments of the invention are perpendicular magnetic anisotropic tunneling junction elements in which the Perpendicular Magnetic Anisotropy (PMA) is established due to the interface of the free layer with the tunnel barrier and the oxide layer, the free layer having thermal stability to at least 400 ℃, and in which the lattice matching layer transforms the oxide layer into a body-centered cubic structure to match the body-centered cubic structure formed in the free layer, which may be used in magnetic memory devices (e.g., magnetoresistive random access memories and spin-torque magnetoresistive random access memories) and spintronic (micro assisted magnetic recording, MAMR), Spin Torque Oscillators (STO), magnetic sensors and biosensors.) as understood by the skilled artisan, the perpendicular magnetic anisotropic tunneling junction may have a bottom spin valve, a top spin valve or a dual spin valve design although the multiple capping layers are typically formed during fabrication of the memory device, the top layer may be used in the embodiments of the invention as the top layer of a perpendicular magnetic anisotropic tunneling junction, and the free layer may be used in a vertical magnetic anisotropic tunneling junction design as illustrated in the top layer of the invention.

In related U.S. Pat. No. 9,147,833, we disclose the use of a laminated (passivated) Hk enhancement layer to achieve high coercivity in a perpendicular magnetic anisotropic tunneling junction device after annealing at 400 deg.C in U.S. Pat. No. 9,425,387, we disclose perpendicular magnetic anisotropic tunneling junctions in which a diffusion barrier is inserted between the Hk enhancement layer and the overlying hard mask to prevent metal in the hard mask from migrating into the Hk enhancement layer and to dilute the interfacial perpendicular magnetic anisotropy established at the free layer/Hk enhancement layer interface.

We have now found that coercivity (Hc) in a perpendicular magnetic anisotropic tunnel junction with a tunnel barrier/free layer/metal oxide layer stack can be further improved by a film layer , hereinafter referred to as a lattice matching layer, which adjoins the oxide layer on the side facing away from the free barrier and has key components to ensure that the oxide layer will completely convert from amorphous to body-centered cubic (BCC) structure.

Referring to fig. 1, a perpendicular magnetic anisotropic magnetic tunneling junction 1 having sidewalls 1s is illustrated according to an embodiment of the present invention, wherein an optional seed layer 11, a reference layer 12, a tunnel barrier 13, a free layer 14, a cap layer 15, a lattice matching layer 16, and a hard mask 17 are sequentially formed on a bottom electrode 10 in a magnetoresistive random access memory, a spin torque magnetoresistive random access memory, or a spin electronics device the bottom electrode may be formed on a substrate (not shown), which in some embodiments is a semiconductor structure, which may include transistors and other related control devices, in a spin torque oscillator device the bottom electrode may be a main magnetic pole (main pole) layer, typically all film layers are sputter deposited in a sputter deposited host structure (main frame) having at least oxidation chambers and etch chambers in a preferred embodiment of , the formation of the tunnel barrier is performed by a first step of depositing a metal layer, either natural oxidation or free radical oxidation to convert a metal oxide to a second metal oxide layer, then a second metal oxide layer is deposited on top of the second metal layer, and a spin field generator layer is generated as a substantially uniform layer, or a spin field generator layer (spin field generator) is generated during a second 36epitaxial process).

Preferably, the seed layer 11 serves to maintain or enhance the perpendicular magnetic anisotropy in the reference layer 12 and promote smooth and uniform crystal growth in the overlying perpendicular magnetic anisotropy MTJ interface layer the seed layer may be or more of NiCr, NiFeCr, Pd, Pt, Ta, Ru, Mg, Ti, Mo or other metals or alloys used in the art to which the invention pertains.

The reference layer 12 is preferably a synthetic antiparallel stack having an AP 2/coupling layer/AP 1 configuration in which the AP1 layer has an interface with the tunnel barrier and AP1 and AP2 are each or more of Co, Fe, CoFe or alloys thereof, which may have additional elements, including or both of Ni and B because of the antiferromagnetic coupling provided by the Ru, Rh, Ir or other Antiferromagnetic (AFM) coupling layer, the AP1 and AP2 layers have magnetic moments in opposite directions_n、(Co/Pd)_n、(Co/Pt)_n、(CoFe/Ni)_n、(Co/NiFe)_n、(Co/NiCo)_nOr other laminated structures exhibiting intrinsic PMI, where n is between 2 and 30And (3) removing the solvent. Preferably, each Co or Co alloy layer in the layered structure has a thickness of 0.5 to 5 angstroms, and each Pd, Pt, Ni, or Ni alloy layer has a thickness of 2 to 10 angstroms. The Co or Co alloy layer is typically thinner than the Ni, Ni alloy, Pt or Pd layer.

In embodiments, a CoFeB/Co transition layer may be formed where the CoFeB portion is 4 to 8 angstroms thick and the Co layer portion is 3 to 5 angstroms thick because Co is more oxidation resistant than the CoFeB (or CoFe) layer, Co generally acts as the uppermost layer in the reference layer stack to form an interface with the tunnel barrier layer.

The tunnel barrier layer 13 may be any metal oxide layer that causes spin-dependent tunneling between the reference layer and the free layer although MgO is generally preferred because MgO provides the best tunneling magnetoresistance ratio, other materials may also be used as the tunnel barrier, including oxides, nitrides, or oxynitrides of MgN, MgON, and Al, Ti, Zn, Hf, AlTi, MgZn, MgTa, or Ta, in addition or a stack of more of the foregoing materials may be selected as the tunnel barrier.

In a bottom spin valve design, the free layer 14 abuts the top surface of the tunnel barrier 13, and according to embodiments, the free layer 14 is a single layer that is of Co, Fe, CoFe, or alloys thereof, and has optional additional elements, or both of Ni and B, however, a bi-or tri-layer configuration represented by FL1/FL2 or FL1/FL2/FL3, where each of FL1, FL2, and FL3 is a magnetic layer formed of Co, Fe, CoFe, or alloys thereof, where via ferromagnetic coupling all magnetic moments of the two or three layers are aligned in the same direction, an alloy containing or two of Ni, B, and a transition metal element containing Ta, Zr, Hf, Mg, Mo, and Nb. in other embodiments, the free layer has a FL1/Ru/FL2 configuration, where FL1 and FL2 layers are anti-ferromagnetic coupling, in yet another embodiment, the free layer is a layered layer as described above with reference to the layered layer configuration described above. (Co/Ni)_nOr of similar composition, is believed to have intrinsic perpendicular magnetic anisotropy.

in embodiments, the free layer 14 has a FL1/A/FL2 stack, where A is a film layer 5 to 10 angstroms thick and is formed of a nonmagnetic element that provides a moment diluting effect, such as Ta, Ti, W, Zr, Hf, Nb, Mo, V, Mg or Cr. FL1 and FL2 layers are ferromagnetically coupled via the A layer.

The free layer induces or enhances the perpendicular magnetic anisotropy in the free layer by the interfacial perpendicular anisotropy created in the portion adjacent to the th interface 20 of the tunnel barrier layer 13 and in the portion adjacent to the second interface 21 of the Hk enhancing layer, which is designed as a cap layer 15 at the bottom spin valve, preferably the interfacial (surface) perpendicular anisotropy exceeds the shape anisotropy field of the free layer to provide the perpendicular magnetic anisotropy and a net magnetization direction perpendicular to both interfaces as a result, this free layer has a higher thermal stability compared to the free layer with in-plane magnetization and a higher Hc. after high temperature processing up to about 400 ℃ it is noted that the thickness of the free layer 14 is represented by "d" in the foregoing equation (4) and therefore the perpendicular anisotropy field increases as the value of "d" decreases.

A cap layer 15 is formed on the free layer 14 and is preferably formed of an oxide, such as MgTaOx, MgO, SiOx, SrTiOx, BaTiOx, CaTiOx, LaAlOx, MnOx, VOx, Al₂O₃ for TiOx, BOx and HfOx, in some embodimentsPreferably, the cap layer is MgO having a non-stoichiometric oxidation state, wherein a specified number of Mg atoms remain unoxidized to achieve less than about 1ohm- μm therein²Is substantially less than the RA value of the tunnel barrier, cases are defined by the sum (RA)_{Tunnel barrier}+RA_{Cover layer}) The total RA of the indicated perpendicular magnetic anisotropy tunneling junction is less than 5 ohm-mum²While in other embodiments, the total RA value is less than 20ohm- μm². The capping layer may be formed by a process similar to that used for the formation of the tunnel barrier, in which a metal or alloy layer is deposited and then oxidized to a stoichiometric or non-stoichiometric oxidation state by a Radical Oxidation (ROX) or Native Oxidation (NOX) process. Since the oxide cap layer contributes to the resistance-area-product (RA) value of the perpendicular magnetic anisotropy tunnel junction without increasing the tunnel magnetoresistance ratio, the thickness of the cap layer is preferably minimized to a value of 2 to 20 angstroms to avoid an undesirably high total RA value.

A key component of embodiments of the present invention is the lattice matching layer 16 formed between the cap layer and the overlying hard mask 17. The lattice matching layer serves to block the influence of the structure of the hard mask during subsequent high temperature processing, which includes annealing at 400 ℃ for several hours. As a result, during processing at 400 ℃, the cap layer transitions from amorphous character to a body centered cubic structure, while the free layer grows into a body centered cubic structure. Thus, a higher perpendicular magnetic anisotropy is achieved in the free layer due to the lattice matching of the free layer and the capping layer. In the prior art, the hardmask metal or alloy contacts the oxide capping layer and tends to prevent part or all of the capping layer from forming a body-centered cubic structure, thereby limiting the vertical magnetic anisotropy in the free layer.

In the th embodiment, the lattice matching layer 16-1 has a bi-layer structure with a lower layer 16a formed of a magnetic material and having a thickness of 2 to 10 angstroms and an upper layer 16b that is a single or multi-layer stack containing or more non-magnetic metals or alloys of M elements, where M is or more of Mo, Mg, Ta, Cr, W, Ru, or VSexual influence, so that the lower layer does not influence the switching behavior in the free layer. The lower layer has Co_XFe_YNi_ZL_WPreferably, where L is of B, Zr, Nb, Hf, Mo, Cu, Cr, Mg, Ta, Ti, Au, Ag or P, and (x + y + z + w) ═ 100 atomic percent, x + y>0, and w>0. After the 400 c anneal process described above, the underlayer 16a has a finite magnetic moment. Further, "x" and "z" may be zero to yield FeL lower layer, or "y" and "z" may be zero to yield CoL lower layer. The content of L is dependent to provide amorphous character in the deposited underlayer and to grow the body-centered cubic in the underlayer during annealing at 400 ℃.

As mentioned above, because the capping layer is thin, the magnetic moment of the lower layer is close to that of the free layer, which typically affects the perpendicular magnetic anisotropy tunneling junction via spin polarization or magnetic dipole field (perpendicular magnetic field) under current. However, forming the M layer on the top surface of the underlayer to a thickness of 2 to 10 angstroms removes any unwanted effects of the underlayer on the free layer. During annealing, the CoFeNiL layer grows a body centered cubic structure, thereby causing similar body centered cubic growth in the cap layer 15 via the interface 22. Body centered cubic crystal growth is typically completed after 30 minutes at a temperature near 400 ℃. However, as the content of the nonmagnetic element L increases, the time required for the transition from the amorphous state to the body-centered cubic structure may increase.

Above the lattice matching layer 16-1 is a hard mask 17 having a thickness in the range of about 50 to 300 angstroms and a top surface 17t that serves as a protective layer for the underlying perpendicular magnetic anisotropic tunneling junction layer during subsequent processing including photoresist patterning and etching (fig. 8), and that provides resistance to chemicals and abrasives during the Chemical Mechanical Polishing (CMP) process shown in fig. 11, in which the top surface of the hard mask is planarized so that the top surface of the hard mask is coplanar with the adjacent insulating layer, the hard mask also serves as an electrical connection from the perpendicular magnetic anisotropic tunneling junction to the top electrode 40 (fig. 12) and provides significant oxidation resistance.

According to a second embodiment shown in FIG. 2, the perpendicular magnetic anisotropy tunnel junction 2 with sidewalls 2s retains all of the layers described above in except for the lattice matching layer embodiments contemplate that depositing the M layer on the underlayer 16a substantially re-sputters all of the underlayer, such that the magnetic material and the M element are Co-deposited on the cap layer 15 to produce a single lattice matching layer 16c with a thickness of 2 to 10 angstroms, and having Co_XFe_YNi_ZL_WM_VComponent (c), wherein (x + y + z + w + v) ═ 100 atomic percent, x + y>0, and v and w are both>0. In , the M content of lattice matching layer 16c may be less in the lower portion than in the upper portion, the lower portion being proximate to the cap layer, the upper portion being proximate to the hard mask 17 during annealing, the CoFeNiLM layer grows into a body centered cubic structure, thereby causing similar body centered cubic growth in cap layer 15 via interface 22.

In a third embodiment, shown in FIG. 3, in Co_XFe_YNi_ZL_WDepositing the M material on the layer may not only form Co with an interface 22 with the capping layer 15_XFe_YNi_ZL_WM_VLayer 16c, and may be of Co_XFe_YNi_ZL_WM_VAn M layer 16b is created on the layers to provide a lattice matching layer 16-2, which is a bi-layer stack having a 16c/16b configuration. In the perpendicular magnetic anisotropic tunneling junction 3 having the sidewall 3s, the layers 16b, 16c each have a thickness of 2 to 10 angstroms. As in the previous embodiments, during the high temperature anneal near 400 ℃, the CoFeNiLM layer grows a body centered cubic structure, thereby promoting body centered cubic growth in the adjoining cap layer.

Embodiments of the present invention also include a fourth embodiment depicted in FIG. 4, wherein the MTJ 4 with the sidewall 4s retains the MTJAll layers in plane 1, except lattice matching layer 16-3, have a three-layer configuration. Specifically, the M deposition process may be controlled to resputter only the upper portion of the underlayer 16a to form Co on the layer 16a_XFe_YNi_ZL_WM_VAnd an alloy layer 16 c. In addition, an M layer 16b may be formed on the top surface of layer 16c to provide a 16a/16c/16b stack for the lattice matching layer 16-3, which is represented in a CoFeNiL/CoFeNiLM/M configuration. Alternatively, the M layer deposition may resputter the upper portion of the lower layer to produce a 16a/16c bilayer with a CoFeNiL/CoFeNiLM configuration for the lattice matching layer 16-3.

FIG. 5 shows a fifth embodiment of the present invention and is a modification of the th embodiment, specifically, a lattice matching layer 16d may be interposed between lattice matching layer 16a and oxide layer 15, the lattice matching layer 16d being an oxide or nitride of Ru, Ta, Ti or Si to create a perpendicular magnetic anisotropic magnetic tunneling junction 5 with sidewalls 5s, preferably layer 16d is amorphous as deposited and grows a body-centered cubic structure during a high temperature anneal to promote body-centered cubic growth in the adjoining oxide layers, furthermore, lattice matching layer 16d may be conductive to avoid additional contributions to the overall RA value, when lattice matching layer 16d is conductive, layer 16d may be as high as 80 angstroms in thickness, such that the overall thickness of stack 16-4 is 2 to 100 angstroms, thus lattice matching layer stack 16-4 has a three layer configuration represented by 16d/16a/16b, where layer 16b contacts hard mask 17, in an alternative embodiment, layer 16a may be omitted to provide a 16d/16b double layer configuration, such as Ru.

Fig. 6 is a sixth embodiment of the present invention comprising all of the mtj layers of fig. 5, except that mtj 5' has a top spin valve configuration, in which optional seed layer 11, layer 16b, optional layers 16a and 16d, Hk enhancing layer 15, free layer 14, tunnel barrier 13, reference layer 12, and hard mask 17 are sequentially formed on bottom electrode 10 in embodiments, the seed layer is omitted because the single or multi-layer structure of the M element in layer 16b may serve as a suitable seed layer.

Embodiments of the invention also contemplate a seventh embodiment having a top spin valve configuration, as in FIG. 7Specifically, an optional seed layer 11, a lattice matching layer 16-1, a Hk enhancement layer 15, a free layer 14, a tunnel barrier 13, a reference layer 12 and a hard mask 17 are formed in sequence on the bottom electrode 10 with an th interface 21 between the bottom surface of the free layer and the top surface of the Hk enhancement layer and a second interface 20 between the top surface of the free layer and the bottom surface of the tunnel barrier, which interfaces create an interfacial vertical anisotropy and a vertical magnetic anisotropy in the free layer, in embodiments seed layer 11 is omitted because or more of the M elements in layer 16b effectively act as seed layers that promote uniform growth of the overlying layers_XFe_YNi_ZL_WLayer 16a is formed on the top surface of M layer 16b and interface 22 is located on the lower surface of Hk enhancing layer 15 and the upper surface of layer 16 a. Similar advantages are achieved with respect to the embodiments of the bottom spin valve in fig. 1-5. That is, a greater perpendicular magnetic anisotropy is obtained in the free layer 14 because the body-centered cubic growth in the layer 16a causes similar body-centered cubic growth in the Hk enhancing layer during annealing. Because substantially all of the amorphous characteristics in the Hk enhancing layer are converted to a body centered cubic structure, there is a higher degree of interface vertical anisotropy at the interface 21 and improved lattice matching with the free layer. Thus, thermal stability and coercivity are maintained in the free layer after treatment at high temperatures of about 400 ℃ for several hours.

In another embodiment of a top spin valve, depicted as perpendicular magnetic anisotropy tunnel junction 2 with sidewalls 2s in FIG. 8, all layers from FIG. 2 are retained, where the lattice matching layer 16c is of the same type as described above with respect to Co_XFe_YNi_ZL_WM_VA single layer of the composition. The present examples contemplate Co_XFe_YNi_ZL_WDeposition of magnetic material on the M layer can resputter all M material and then co-deposit with CoFeNiL material. The M material may be uniformly distributed in the CoFeNiLM layer. In other embodiments, the M content in the lower portion of layer 16c may be higher than the M content in the upper portion adjacent to the Hk enhancing layer 15. At temperatures close to 400 deg.CDuring the high temperature anneal at temperature, the CoFeNiLM layer grows a body centered cubic structure, thereby promoting growth of the body centered cubic structure in the adjoining Hk enhancing layer to be lattice matched to the body centered cubic growth in the free layer 14.

According to a ninth embodiment of the invention shown in FIG. 9, a perpendicular magnetic anisotropy tunnel junction 3' with sidewalls 3s is formed with a top spin valve structure that retains all layers from FIG. 7 except that the lattice matching layer 16-2 with a 16b/16c bi-layer stack has Co formed on the M layer 16b_XFe_YNi_ZL_WM_VAnd (c) a layer 16 c. In other words, the aforementioned Co on the M layer can be controlled_XFe_YNi_ZL_WLayer deposition such that only the upper part of the M layer is resputtered, then with Co_XFe_YNi_ZL_WCo-deposition of materials to produce Co_XFe_YNi_ZL_WM_VAlloy layer 16 c. as in the previous embodiment, the CoFeNiLM layer is important to promote body-centered cubic growth in the adjacent Hk enhancing layer 15, as in , the Hk enhancing layer forms a crystal structure that matches the crystal structure of the free layer 14, thereby substantially preserving the perpendicular magnetic anisotropy in the free layer during high temperature processing at approximately 400 ℃ for several hours.

Referring to fig. 10, embodiments of the present invention include a tenth embodiment of a perpendicular magnetic anisotropic tunneling junction 4' depicted with sidewalls 4s, wherein all layers from the top spin valve structure in fig. 4 are retained except that the lattice matching layer 16-3 has a tri-layer configuration represented by 16b/16c/16a with the aforementioned M/CoFeNiLM/CoFeNiL stack. Here, Co can be controlled_XFe_YNi_ZL_WDeposition of material on the M layer 16b such that only the upper portion of the M layer is resputtered to produce Co on the lower layer 16b_XFe_YNi_ZL_WM_VAnd (c) a layer 16 c. Then, Co deposition is continued_XFe_YNi_ZL_WLayer such that a CoFeNiL layer 16a is formed on layer 16 c. Here, layers 16a ℃16c each have a thickness of 2 to 10 angstroms. Thus, as previously described, the CoFeNiL layer contacts the Hk enhancing layer 15 at the interface 22 and is important to ensure that a body-centered cubic structure is formed in the Hk enhancing layer during the annealing process including temperatures near 400 ℃.

Embodiments of the present invention also include a method of forming a perpendicular magnetic anisotropic tunnel junction device having the structure disclosed at of the embodiment shown in fig. 1-10, referring to fig. 11, a perpendicular magnetic anisotropic tunnel junction stack is formed on a substrate comprising a bottom electrode layer 10, according to the bottom spin valve embodiment, a seed layer 11, a reference layer 12, a tunnel barrier 13, a free layer 14, a capping layer 15, a lattice matching layer 16-1, and a hard mask 17 are sequentially formed on the substrate, it being understood that the lattice matching layer 16c, 16-2, 16-3, or 16-4 may replace layer 16-1, all layers may be deposited by sputter deposition techniques in a preferred embodiment, the tunnel layer is formed by depositing a metal (or alloy) layer, oxidizing a metal layer with natural or free oxygen oxidation, then depositing a second metal or alloy layer on the oxidized metal layer, in the case of , the second metal layer may be oxidized, and depositing a third metal layer on the oxidized second metal layer, followed by removing the third metal layer in a normal oxygen anneal process.

Referring to fig. 12, a photoresist layer is deposited on the top surface 17t of the hard mask and is pattern exposed and developed by conventional methods to form a photoresist mask 30 having a desired shape in a plan view schematic (not shown) of a magnetoresistive random access memory, a spin torque magnetoresistive random access memory, or a spintronic device. Thereafter, ion beam etching or reactive ion etching is used to transfer the photoresist mask pattern through the underlying layer to form sidewalls 1s stopping on the bottom electrode top surface 10 t. In the exemplary embodiment, the sidewalls 1s and 50s are formed along a continuous surface substantially perpendicular to the top surface of the bottom electrode 10. In other embodiments, the sidewalls 1s may be aligned obliquely such that the seed layer has a width in the x-axis direction greater than the hard mask 17. Here, the thickness of each of the vertical magnetic anisotropy tunnel junction layers is related to the distance along the y-axis direction. Preferably, the free layer 14 and the reference layer 12 have magnetizations in the (+) y-axis or (-) y-axis directions.

Referring to FIG. 13, an insulating layer 25, such as alumina or SiO, is deposited on top surface 10t and sidewalls 1s₂The thickness of the insulating layer 25 is at least equal to the thickness of the perpendicular magnetic anisotropy tunnel junction stack. Then, a Chemical Mechanical Polishing (CMP) process is performed to remove the photoresist mask and form a top surface 25t on the insulating layer, the top surface 25t being coplanar with the top surface 17t of the hard mask layer in the perpendicular magnetic anisotropic tunneling junction. The perpendicular magnetic anisotropy tunnel junction is now considered a nanopillar (nanopillar) because its structure resembles a cylinder with lateral dimensions along the x-axis and z-axis and a thickness along the y-axis. From a top view (not shown), the mtj nano-pillars may have a circular, elliptical, or polygonal shape.

Thereafter, in FIG. 14, a top electrode layer is formed in a second insulating layer (not shown) by known processes to complete a MRAM, spin torque MRAM, or spin torque oscillator fabrication sequence, the top electrode 20 contacts the top surface of the hard mask 17 and is typically of a plurality of parallel lines formed in an MRAM array and typically comprises Cu or other effective electrical conductor in embodiments, a cladding (cladding) layer (not shown) is formed around the conductive layer in embodiments, for simplicity of the drawing and focusing on the perpendicular magnetic anisotropic tunneling junction structure, which is a key component of embodiments of the invention, only top electrodes are shown.

The formation of the perpendicular magnetic anisotropy tunnel junction with the top spin valve design as shown in fig. 6-10 follows the same process flow as shown in fig. 11-14 except that the order of the perpendicular magnetic anisotropy tunnel junction layers is changed. Specifically, an optional seed layer 11, a lattice matching layer 16-1 (or 16c, 16-2, 16-3, 16-4), a Hk enhancing layer 15, a free layer 14, a tunnel barrier 13, a reference layer 12 and a hard mask 17 are sequentially formed on the bottom electrode 10, and then a sidewall 1s (or 2s, 3s, 4s or 5s) is produced by using the aforementioned photoresist patterning and etching process with reference to fig. 10.

To show the benefits of the lattice matching layers according to embodiments of the invention, patterned perpendicular mtj nano-pillars were fabricated as circular 90-100 nm mram devices and respective Hc fields were measured, the reference perpendicular mtj a had a seed layer/reference layer/MgO tunnel barrier/free layer/MgO cap layer/Ru/Ta/TiN configuration, where the reference layer and free layer are CoFeB based materials, the tunnel barrier and cap layer are MgO, and the hard mask is a Ru/Ta/TiN stack, the embodiment according to embodiments of the invention formed perpendicular mtj B and differed from the reference only by including a lattice matching layer with CoFeB/Mo configuration between the cap layer and hard mask, all structures were deposited at room temperature, and annealed at 330 ℃ for 30 minutes for a second time a coercivity measurement result showing that Hc of the two samples was 3200 (Oe), then annealed at 400 ℃ for a second time 151 minutes, followed by a second time anneal for a second time 1600 minutes, and no further significant change to be measured as a high temperature anneal at least 400 c, which was not expected to be reduced by a further anneal after the second time of the hcc anneal, which was measured as a high temperature anneal at least 35.

Table 1: the result is a perpendicular magnetic anisotropy tunneling junction with CoFeB/MgO/CoFeB/cap layer/Lattice Matching (LM)/hard mask configuration.

A benefit of embodiments of the present invention is that the free layer in the magnetic device is improved in perpendicular magnetic anisotropy (Hc and Hk) which increases the retention time of memory elements such as perpendicular magnetic anisotropy MTJ, followed by high temperature processing up to 400 ℃ which is required for MRAM or spin torque MRAM devices integrated in CMOS structures.

While embodiments of the invention have been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of embodiments of the invention.