CN112490353A - Magnetic random access memory storage unit and magnetic random access memory - Google Patents

Magnetic random access memory storage unit and magnetic random access memory Download PDF

Info

Publication number
CN112490353A
CN112490353A CN201910860738.8A CN201910860738A CN112490353A CN 112490353 A CN112490353 A CN 112490353A CN 201910860738 A CN201910860738 A CN 201910860738A CN 112490353 A CN112490353 A CN 112490353A
Authority
CN
China
Prior art keywords
layer
cofeb
free layer
free
magnetic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN201910860738.8A
Other languages
Chinese (zh)
Inventor
张云森
肖荣福
郭一民
陈峻
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shanghai Ciyu Information Technologies Co Ltd
Original Assignee
Shanghai Ciyu Information Technologies Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shanghai Ciyu Information Technologies Co Ltd filed Critical Shanghai Ciyu Information Technologies Co Ltd
Priority to CN201910860738.8A priority Critical patent/CN112490353A/en
Publication of CN112490353A publication Critical patent/CN112490353A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N50/00Galvanomagnetic devices
    • H10N50/10Magnetoresistive devices

Landscapes

  • Mram Or Spin Memory Techniques (AREA)
  • Hall/Mr Elements (AREA)

Abstract

The invention discloses a magnetic random access memory storage unit and a magnetic random access memory, wherein the storage unit comprises a reference layer, a barrier layer and a first free layer which are arranged in a stacking way, a second free layer is further arranged above the first free layer, a vertical magnetic coupling layer is arranged below the second free layer, and the vertical magnetic coupling layer is superposed with a magnetic damping barrier layer arranged above the second free layer; the vertical magnetic coupling layer is used for realizing the strong magnetic coupling of the first free layer and the second free layer and providing an additional vertical interface anisotropy source; the magnetic damping barrier layer provides an additional source of anisotropy while reducing the magnetic damping coefficient of the film layer. The addition of the second free layer increases the thickness of the free layer, reduces the magnetic damping coefficient, increases the thermal stability factor, and the critical write current is not increased.

Description

Magnetic random access memory storage unit and magnetic random access memory
Technical Field
The present invention relates to the field of magnetic random access memory, and more particularly, to a magnetic random access memory cell having a double free layer and a magnetic random access memory.
Background
In recent years, Magnetic Random Access Memory (MRAM) using Magnetic Tunnel Junction (MTJ) is considered as a future solid-state nonvolatile Memory, which has the characteristics of high speed reading and writing, large capacity, and low power consumption. Ferromagnetic MTJs are typically sandwich structures with a magnetic memory layer (free layer) that can change the magnetization direction to record different data; an insulating tunnel barrier layer in the middle; and the magnetic reference layer is positioned on the other side of the tunnel barrier layer, and the magnetization direction of the magnetic reference layer is unchanged.
In order to be able to record information in such a magnetoresistive element, a writing method based on Spin momentum Transfer (STT) switching technology has been proposed, and such an MRAM is called STT-MRAM. STT-MRAM is further classified into in-plane STT-MRAM and perpendicular STT-MRAM (i.e., pSTT-MRAM), which have better performance depending on the direction of magnetic polarization. In a Magnetic Tunnel Junction (MTJ) having Perpendicular Anisotropy (PMA), as a free layer for storing information, there are two magnetization directions in the Perpendicular direction, that is: up and down, corresponding to "0" and "1" or "1" and "0" in the binary, respectively. In practical application, the magnetization direction of the free layer is kept unchanged when information is read or the free layer is empty; during writing, if there is a signal input in a different state from the existing state, the magnetization direction of the free layer will be flipped by 180 degrees in the vertical direction. The ability of the free layer of a magnetic memory to maintain the magnetization direction in this vacant state is called Data Retention (Data Retention) or Thermal Stability (Thermal Stability). The requirements are different in different application scenarios. A thermal stability requirement for a typical Non-volatile Memory (NVM) is that data can be stored for 10 years at 125 ℃.
In addition, MTJ, which is the core memory cell of magnetic memory (MRAM), must also be compatible with CMOS processes and must be able to withstand long term annealing at 400 ℃.
FIG. 1 is a diagram illustrating a conventional MRAM cell structure. The conventional magnetic random access memory cell comprises a bottom electrode 11, a seed layer 20, an antiparallel ferromagnetic superlattice layer 30 (including a lower ferromagnetic layer 31, an antiparallel ferromagnetic coupling layer 32, and an upper ferromagnetic layer 33), a lattice blocking layer 40, a reference layer 50, a barrier layer 60, a free layer 70 (including a free layer (I)71, a free layer (II)72, a free layer (III)73), a capping layer 80, and a top electrode 12, which are sequentially stacked from bottom to top.
The structure of the free layer 70 of the conventional magnetic random access memory cell is generally composed of a free layer (I)71, a free layer (II)72 and a free layer (III)73, such as CoFeB, CoFe/CoFeB, Fe/CoFeB or CoFeB/(Ta, W, Mo, Hf)/CoFeB, etc., and in order to increase the density of the magnetic memory, the Critical Dimension (Critical Dimension) of the magnetic tunnel junction has been made smaller and smaller in recent years. When the size is further reduced, it is found that Thermal Stability (Thermal Stability Factor) of the magnetic tunnel junction is drastically deteriorated. For ultra-small sized MRAM magnetic memory cells, to improve thermal stability, the thickness of the free layer can typically be reduced, the saturation susceptibility of the free layer can be reduced, or the interfacial anisotropy can be increased. If the thickness of the free layer is reduced, the Tunneling Magnetoresistance Ratio (TMR) is reduced, which increases the error rate in the read operation. Under the condition of unchanged thickness, the addition or change of the free layer into a material with low saturation magnetic susceptibility can also reduce Tunneling Magnetoresistance (TMR) and is not beneficial to the reading operation of the device.
Disclosure of Invention
In order to solve the problems of the prior art, the present invention provides a Magnetic Random Access Memory (MRAM) and a Memory cell having a dual free layer, wherein a second free layer is disposed between an original free layer and a capping layer of the MRAM having a Perpendicular Anisotropy (PMA), and the addition of the second free layer does not affect a tunneling magnetoresistance ratio, increases a thickness of the free layer, reduces a Magnetic damping coefficient, increases a thermal stability factor, and does not increase a critical write current.
The purpose of the application and the technical problem to be solved are realized by adopting the following technical scheme. The invention provides a magnetic random access memory storage unit with a double-layer free layer, which comprises a reference layer, a barrier layer and a first free layer which are arranged in a stacking mode, wherein a second free layer is further arranged above the first free layer, a perpendicular magnetic coupling layer is arranged below the second free layer, and a magnetic damping barrier layer is arranged above the second free layer, wherein a magnetization vector in the second free layer is always perpendicular to an interface of the first free layer and is parallel to a magnetization vector in the first free layer.
In an embodiment of the present application, the first free layer includes a first free layer (I), a first free layer (II), and a first free layer (III) which are stacked, and the perpendicular magnetic coupling layer is disposed between the first free layer and the second free layer, the perpendicular magnetic coupling layer being for achieving magnetic coupling between the first free layer and the second free layer.
In the embodiment of the present application, further, the total structural thickness of the second free layer is 0.5 to 3.0 nm. The second free layer is made of Co/(Pt, Pd, Ni or Ir)/(CoFeB, CoB or FeB), (CoFeB, CoB or FeB)/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoB or FeB)/Co/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoB or FeB)/(Pt, Pd, Ni or Ir)/(CoFeB, CoFeB or FeB), Co/(Pt, Pd, Ni or Ir)/Co/(CoFeB, CoB or FeB), (CoFeB, CoB or FeB)/X/Co/(Pt, Pd, Ni, Ir)/Co/X/(CoFeB, CoB or FeB), (CoFeB, CoFeB or FeB)/X/Co/(Pt, Pd, Ni or Ir), (CoFeB, CoFeB/X/Co/(CoFeB, CoFeB or FeB), (CoFeB, Ni or Ir), Co/(Pt, Pd, Ni or Ir)/Co/X/(CoFeB, CoB or FeB) multilayer structure.
Wherein X is W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru or Os. The atomic percent of B in FeB or CoB is 15-40%; in the CoFeB alloy, Co: the atomic ratio of Fe is 1:3 to 3:1, and the atomic percentage of B is 15-40%.
In an embodiment of the present application, further, the perpendicular magnetic coupling layer is made of a non-magnetic metal oxide including MgO, ZrO2, ZnO, Al2O3, GaO, Y2O3, SrO, Sc2O3, TiO2, HfO2, V2O5, Nb2O5, Ta2O5, CrO3, MoO3, WO3, RuO2, OsO2, TcO, ReO, RhO, IrO, SnO, SbO, MgZnO, MgBO, or MgAlO or a combination thereof, and more preferably MgO may be selected.
In an embodiment of the present application, further, the magnetic damping barrier layer is made of a non-magnetic metal or an oxide thereof, and the non-magnetic metal or the oxide thereof includes a non-magnetic metal or an oxide thereof made of Mg, Zr, Zn, Al, Ga, Y, Sr, Sc, Ti, V, Nb, Cr, Os, Tc, Re, Rh, Ir, Sn, Sb, MgO, ZrO2, ZnO, Al2O3, GaO, Y2O3, SrO, Sc2O3, TiO2, HfO2, V2O5, Nb2O5, Ta2O5, CrO3, MoO3, WO3, RuO2, OsO2, TcO, ReO, RhO, IrO, SnO, SbO, MgZnO, MgBO, MgAlO, or the like, or a combination thereof, and MgO may be preferably selected.
In an embodiment of the present application, the first free layer is made of a variable magnetic polarization, and the first free layer is made of a stacked CoFeB, CoFe/CoFeB, Fe/CoFeB, CoFeB/(W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru, Os, Ru, Rh, Ir, Pd, Pt)/CoFeB, Fe/CoFeB/(W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru, Os, Ru, Rh, Ir, Pd, Pt)/CoFeB or CoFe/CoFeB/(W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru, Os, Ru, Rh, Ir, Pd, Pt)/CoFeB structure.
In an embodiment of the application, further, the barrier layer is made of a non-magnetic metal oxide comprising MgO, MgZnO, MgBO, MgAlO or a combination thereof, preferably MgO may be selected.
In an embodiment of the present application, the present invention provides a magnetic random access memory, which includes the memory cell as described above, and further includes a bottom electrode, a seed layer, an antiparallel ferromagnetic superlattice layer, a lattice partition layer, a capping layer, and a top electrode, wherein the bottom electrode, the seed layer, the antiparallel ferromagnetic superlattice layer, the lattice partition layer, the reference layer, the barrier layer, the first free layer, the perpendicular magnetic coupling layer, the second free layer, the magnetic damping barrier layer, the capping layer, and the top electrode are stacked in sequence.
In an embodiment of the present application, further, the antiparallel ferromagnetic superlattice layer comprises a lower ferromagnetic superlattice layer, an antiparallel ferromagnetic coupling layer, and an upper ferromagnetic layer, the antiparallel ferromagnetic superlattice layer having [ Co/P ]t]nCo/(Ru,Ir,Rh)、[Co/Pt]nCo/(Ru,Ir,Rh)/Co[Pt/Co]m、[Co/Pd]nCo/(Ru,Ir,Rh)、[Co/Pd]nCo/(Ru,Ir,Rh)/Co[Pd/Co]m、[Co/Ni]nCo/(Ru, Ir, Rh) or [ Co/Ni ]]nCo/(Ru,Ir,Rh)/Co[Ni/Co]mA superlattice structure, wherein n is more than or equal to 1, and m is more than or equal to 0.
In an embodiment of the present application, further, the bottom electrode is made of Ti, TiN, Ta, TaN, W, WN, or a combination thereof. The top electrode is made of Ta, TaN, Ti, TiN, W, WN or a combination material thereof.
In an embodiment of the present application, further, the seed layer is made of Ta, Ti, TiN, TaN, W, WN, Ru, Pt, Ni, Cr, NiCr, CrCo, CoFeB, CoFeC or a combination thereof, and the seed layer has a multi-layer structure of Ta/Ru, Ta/Pt, CoFeB/Ta/Pt/Ru or Ta/Pt/Ru;
in an embodiment of the present application, the lattice partition layer is made of Ta, W, Mo, Hf, Fe, Co (Ta, W, Mo or Hf), Fe (Ta, W, Mo or Hf), FeCo (Ta, W, Mo or Hf) or FeCoB (Ta, W, Mo or Hf), and has a thickness of 0.1nm to 0.5 nm.
In an embodiment of the present application, the capping layer is made of CoFeB, CoFeC, W, Mo, Mg, Nb, Ru, Hf, V, Cr or Pt material, and the capping layer has a (W, Mo, Hf)/Ru double-layer structure or a Pt/(W, Mo, Hf)/Ru triple-layer structure.
In an embodiment of the present application, further, after the bottom electrode, the seed layer, the antiparallel ferromagnetic superlattice layer, the lattice partition layer, the reference layer, the barrier layer, the first free layer, the perpendicular magnetic coupling layer, the second free layer, the magnetic damping barrier layer, the capping layer, and the top electrode are deposited, an annealing operation is performed at a temperature of 350 ℃ or more for at least 60 minutes.
The magnetic random access memory storage unit with the thermal stability enhancement layer can produce the following beneficial effects: the Tunneling Magnetic Resistance (TMR) is not influenced by the addition of the second free layer, the thickness of the free layer is increased, the damping coefficient is reduced, the thermal stability factor is increased, and the critical write current is not increased.
a. The added second free layer and the first free layer are in ferromagnetic coupling, and under the condition of thermal disturbance or an external magnetic field, in order to make the magnetization vector of the free layer turn, energy larger than the sum of the energy barrier of the first free layer and the energy barrier of the added second free layer is required to be provided, so that the thermal stability is greatly improved.
b. The addition of the second free layer in the implementation of the present application has no influence on Tunneling Magnetoresistance (TMR).
c. A non-magnetic metal layer or metal oxide, preferably MgO, having a thickness of 0.3nm to 1.5nm and 0.5nm to 3.0nm, is deposited both after and after the deposition of the second free layer. This additionally provides a source of interfacial anisotropy, further increasing thermal stability; in addition, the magnetic damping barrier layer arranged above the second free layer is added, so that the damping coefficient of the whole film layer structure is effectively reduced, and the write current is favorably reduced.
d. The magnetic random access memory storage unit and the magnetic random access memory can withstand long-time annealing at 400 ℃.
e. Due to the addition of the second free layer, the thickness of the whole free layer is increased, the reduction of the damping coefficient is facilitated, and therefore the critical write current cannot be increased.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a diagram illustrating a prior art MRAM cell;
FIG. 2 is a diagram illustrating a MRAM cell structure according to an embodiment of the invention.
Wherein the reference numerals include:
, 11: bottom electrode, 12: top electrode, 20: seed layer, 30: antiparallel ferromagnetic superlattice layer, 31: lower ferromagnetic layer, 32: antiparallel ferromagnetic coupling layer, 33 upper ferromagnetic layer, 40: lattice partition layer, 50: reference layer, 60: barrier layer, 70: free layer, 71: free layer (I), 72: free layer (II), 73: free layer (III), 80: capping layer.
The invention is directed to 110: bottom electrode, 120: top electrode, 200: seed layer, 300: antiparallel ferromagnetic superlattice layer, 310: lower ferromagnetic layer, 320: antiparallel ferromagnetic coupling layer, 330: upper ferromagnetic layer, 400: lattice partition layer, 500: reference layer, 600: barrier layer, 700: first free layer, 710: first free layer (I), 720: first free layer (II), 730: first free layer (III), 800: capping layer, 910: perpendicular magnetic coupling layer, 920: second free layer, 930: magnetoresistive barrier layer.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, apparatus, article, or device that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or device.
In one embodiment of the present invention, there is provided a Magnetic Random Access Memory (MRAM) memory cell having a dual free layer interposed between a top of a first free layer and a capping layer (capping layer) without vacuum interruption during Physical Vapor Deposition (PVD) of a MRAM magnetic tunnel junction (mtj) multilayer film, as shown in fig. 2, the MRAM memory cell having the dual free layer including a reference layer 500, a barrier layer 600, a first free layer 700, a second free layer 920 above the first free layer 700, and a perpendicular magnetic coupling layer 910 below the second free layer 920, a magnetic damping barrier layer 930 above the second free layer 920, wherein a magnetization vector in the second free layer 920 is always perpendicular to the first free layer 700 interface, and is parallel to the magnetization vector in the first free layer 700.
In a preferred embodiment of the present invention, a magnetic random access memory is provided, which comprises the memory cell as described above, and further comprises a bottom electrode 110, a seed layer 200, an antiparallel ferromagnetic superlattice layer 300, a lattice partition layer 400, a capping layer 800, and a top electrode 120. The bottom electrode 110, the seed layer 200, the antiparallel ferromagnetic superlattice layer 300, the lattice partition layer 400, the reference layer 500, the barrier layer 600, the first free layer 700, the perpendicular magnetic coupling layer 910, the second free layer 920, the magnetic damping barrier layer 930, the capping layer 800, and the top electrode 120 are sequentially stacked.
The bottom electrode 110 is made of Ti, TiN, Ta, TaN, W, WN or a combination thereof, and is generally implemented by Physical Vapor Deposition (PVD), and after Deposition, the bottom electrode is usually planarized to achieve surface flatness for fabricating the magnetic tunnel junction.
The seed layer 200 is typically composed of Ta, Ti, TiN, TaN, W, WN, Ru, Pt, Ni, Cr, CrCo, CoFeB, or combinations thereof; further, the seed layer 210 may be a multilayer structure of Ta/Ru, Ta/PtCoFeB/Ta/Pt, CoFeB/Ta/Pt/Ru, or Ta/Pt/Ru. To optimize the crystal structure of the subsequent antiparallel ferromagnetic superlattice layer 300.
The Anti-Parallel ferromagnetic super-lattice layer (Anti-Parallel ferromagnetic super-lattice) 300, also called Synthetic Anti-ferromagnetic layer (SyAF), is generally made of [ Co/Pt [ ]]nCo/(Ru,Ir,Rh)、[Co/Pt]nCo/(Ru,Ir,Rh)/Co[Pt/Co]m、[Co/Pd]nCo/(Ru,Ir,Rh)、[Co/Pd]nCo/(Ru,Ir,Rh)/Co[Pd/Co]m、[Co/Ni]nCo/(Ru, Ir, Rh) or [ Co/Ni ]]nCo/(Ru,Ir,Rh)/Co[Ni/Co]mThe superlattice structure is formed, wherein n is larger than or equal to 1, m is larger than or equal to 0, and the antiparallel ferromagnetic superlattice layer 300 has strong perpendicular anisotropy (PMA).
The reference layer 500 has a magnetic polarization invariant under ferromagnetic coupling of the antiparallel ferromagnetic superlattice layer 300. the reference layer 500 is typically made of Co, Fe, Ni, CoFe, CoFeB, or combinations thereof. since the antiparallel ferromagnetic superlattice layer 300 has a face-centered cubic (FCC) crystal structure, and the crystal structure of the reference layer 500 is body-centered cubic (BCC), the lattices of the two subjects are not matched, in order to realize the transition and ferromagnetic coupling from the antiparallel ferromagnetic superlattice layer 300 to the reference layer 500, a lattice isolation layer 400 is usually added between the two layers of materials of the antiparallel ferromagnetic superlattice layer 300 and the reference layer 500, and the lattice isolation layer 400 is usually made of Ta, W, Mo, Hf, Fe, Co (Ta, W, Mo or Hf), Fe (Ta, W, Mo or Hf), FeCo (Ta, W, Mo or Hf) or FeCoB (Ta, W, Mo or Hf) with a thickness of 0.1nm to 0.5 nm.
The barrier layer 600 is made of a non-magnetic metal oxide including MgO, MgZnO, MgBO, MgAlO or a combination thereof, and more preferably, MgO may be selected.
The first free layer 700 has a variable magnetic polarization, and the first free layer 700 is typically formed of a material selected from the group consisting of CoFeB, CoFe/CoFeB, Fe/CoFeB, CoFeB/(W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru, Os, Ru, Rh, Ir, Pd, Pt)/CoFeB, Fe/CoFeB/(W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru, Os, Ru, Rh, Ir, Pd, Pt)/CoFeB, and CoFe/CoFeB/(W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru, Os, Ru, Rh, Ir, Pd, Pt)/CoFeB. The first free layer 700 may further be made of a stack of CoFeB/(W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru, Os, Ru, Rh, Ir, Pd, Pt)/CoFeB, Fe/CoFeB/(W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru, Os, Ru, Rh, Ir, Pd, Pt)/CoFeB or CoFe/CoFeB/(W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru, Os, Ru, Rh, Ir, Pd, Pt)/CoFeB structures. .
Taking the structure of the first free layer 700 as an example, it is common in the art that the first free layer 700 is formed from a first free layer (I)710, a first free layer (II)720, and a first free layer (III)730 from bottom to top, respectively. The CoFeB/(W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru, Os, Ru, Rh, Ir, Pd, Pt)/CoFeB structure represents a three-layer structure of the first free layer (I)710, the first free layer (II)720, the first free layer (III)730 formed, the first free layer (I)710 and the one free layer (III)730 are made of CoFeB material, and the intermediate layer first free layer (II)720 is made of W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru, Os, Ru, Rh, Ir, Pd, or Pt material, and the following structural expressions are similar and will not be explained again.
Wherein the total structural thickness of the second free layer is 0.5-3.0 nm. The second free layer is made of Co/(Pt, Pd, Ni or Ir)/(CoFeB, CoB or FeB), (CoFeB, CoB or FeB)/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoB or FeB)/Co/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoB or FeB)/(Pt, Pd, Ni or Ir)/(CoFeB, CoFeB or FeB), Co/(Pt, Pd, Ni or Ir)/Co/(CoFeB, CoB or FeB), (CoFeB, CoB or FeB)/X/Co/(Pt, Pd, Ni, Ir)/Co/X/(CoFeB, CoB or FeB), (CoFeB, CoFeB or FeB)/X/Co/(Pt, Pd, Ni or Ir), (CoFeB, CoFeB/X/Co/(CoFeB, CoFeB or FeB), (CoFeB, Ni or Ir), Co/(Pt, Pd, Ni or Ir)/Co/X/(CoFeB, CoB or FeB) multilayer structure.
Wherein X is W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru or Os. The atomic percent of B in FeB or CoB is 15-40%; in the CoFeB alloy, Co: the atomic ratio of Fe is 1:3 to 3:1, and the atomic percentage of B is 15-40%.
In practice, a perpendicular magnetic coupling layer 910 of a non-magnetic metal oxide layer is deposited before the addition of the second free layer 920, said non-magnetic metal oxide layer comprising MgO, ZrO2, ZnO, Al2O3, GaO, Y2O3, SrO, Sc2O3, TiO2, HfO2, V2O5, Nb2O5, Ta2O5, CrO3, MoO3, WO3, RuO2, OsO2, TcO, ReO, RhO, IrO, SnO, SbO, MgZnO, MgBO or MgAlO or a combination thereof, preferably MgO. The perpendicular magnetic coupling layer 910 has a thickness of 0.3nm to 1.5nm, which also provides a source of interfacial anisotropy, thereby increasing thermal stability.
In addition, a magnetic damping blocking layer 930 is arranged above the second free layer 920, and the magnetic damping blocking layer 930 effectively reduces the damping coefficient of the whole film structure, which is beneficial to reducing the writing current. Wherein the magnetic damping barrier 930 is made of a non-magnetic metal or an oxide thereof including Mg, Zr, Zn, Al, Ga, Y, Sr, Sc, Ti, V, Nb, Cr, Os, Tc, Re, Rh, Ir, Sn, Sb, MgO, ZrO2, ZnO, Al2O3, GaO, Y2O3, SrO, Sc2O3, TiO2, HfO2, V2O5, Nb2O5, Ta2O5, CrO3, MoO3, WO3, RuO2, OsO2, TcO, ReO, RhO, IrO, SnO, SbO, MgZnO, MgBO, MgAlO, etc. or a combination thereof, and more preferably MgO, the magnetic damping barrier 930 has a thickness of 0.5nm to 3.0 nm.
The material of the covering layer 800 is CoFeB, CoFeC, W, Mo, Mg, Nb, Ru, Hf, V, Cr or Pt, and the like, and preferably can be made by stacking structures such as (W, Mo, Hf)/Ru or/Pt/(W, Mo, Hf)/Ru.
The top electrode 120 can be made of Ta, TaN, TaN/Ta, Ti, TiN, TiN/Ti, W, WN, WN/W or their combination.
After deposition of all the film layers, an anneal at 400 ℃ for 90 minutes is selected to cause the reference layer 500, the first free layer 700, and the multilayer second free layer 900 to change phase from amorphous to Body Centered Cubic (BCC) crystal structures.
The invention provides a magnetic random access memory thermal stability enhancement layer, which is characterized in that a second free layer 920 is inserted between the top of a first free layer 700 and a covering layer 800 under the condition of not cutting off vacuum in the process of Physical Vapor Deposition (PVD) of an MRAM magnetic tunnel junction multilayer film.
In the addition of the second free layer 920, the magnetization vector of the second free layer 920 is always perpendicular to the first free layer 700 and parallel to the magnetization vector of the first free layer 700, and since the addition of the second free layer 920 and the first free layer 700 exhibit ferromagnetic coupling, under thermal disturbance or an applied magnetic field, an energy greater than the sum of the energy barrier of the first free layer 700 and the energy barrier of the second free layer 920 must be provided in order to flip the magnetization vector of the second free layer 920 in the addition of the multi-layer second free layer 900.
Experiments have shown that the addition of the additional multi-layered multi-layer second free layer 900 does not affect the Tunneling Magnetoresistance Ratio (TMR).
Also, a non-magnetic metal oxide layer is deposited before and after the deposition of the additional second free layer 920, which additionally provides a source of interfacial anisotropy and thus increased thermal stability. In addition, the magnetic damping barrier layer 930 is arranged above the second free layer 920, so that the damping coefficient of the whole film structure is effectively reduced, and the write current is favorably reduced.
Also, since Ta and its nitride are successfully avoided when selecting the material of the first free layer 700 and the material of the capping layer 800, it can withstand a long-time annealing at 400 ℃.
Further, since the thickness of the free layer is increased due to the addition of the second free layer 920, it is advantageous in terms of the reduction of damping constant (α), and at the same time, when selecting the materials of the coupling layer of the first free layer 700/second free layer 920 and the capping layer 800, a material having a low damping coefficient may be preferable, which may further reduce the damping coefficient. When writing to the device, the critical write current does not increase due to the reduced damping coefficient, despite the increased thermal stability factor.
Further, the Data Retention capability (Data Retention) can be calculated by the following formula:
Figure BDA0002199681660000111
wherein tau is the time when the magnetization vector is unchanged under the condition of thermal disturbance, tau0For the trial time (typically 1ns), E is the energy barrier of the free layer, kBBoltzmann constant, T is the operating temperature.
The Thermal Stability factor (Thermal Stability factor) can then be expressed as the following equation:
Figure BDA0002199681660000121
wherein, KeffIs the effective anisotropic energy density of the free layer, V is the volume of the free layer, KV is the bulk anisotropy constant MsSaturation magnetic susceptibility of the free layer, NzDemagnetization constant in the vertical direction, t is the thickness of the free layer, KiCD is the critical dimension of the MRAM (i.e., the diameter of the free layer), As is the stiffness integral exchange constant, and k is the critical dimension of the free layer switching mode transition from domain switching (i.e., Magnetization switching processed by "macro-spin") to reverse domain nucleation/growth (i.e., Magnetization switching processed by nuclear of reversed domain and propagation of a domain wall) mode. Experiments show that when the thickness of the free layer is thicker, the free layer shows in-plane anisotropy, and when the thickness of the free layer is thinner, the free layer shows vertical anisotropy, KVIt is generally negligible and the contribution of the demagnetization energy to the perpendicular anisotropy is negative, so the perpendicular anisotropy comes entirely from the interfacial effect (Ki).
In addition, as the volume of the magnetic free layer is reduced, the smaller the spin polarization current to be injected for writing or switching operation, and the critical current I for writing operationc0The relationship between the compound and the thermal stability is strongly related, and can be expressed as the following formula:
Figure BDA0002199681660000122
wherein alpha is a damping constant,
Figure BDA0002199681660000123
η is the spin polarizability, which is the approximate planck constant.
The addition of the additional second free layer 920 of the present invention does not affect TMR, increases the thickness of the whole free layer, reduces the damping coefficient, increases the thermal stability factor, and the critical write current is not increased.
The terms "in one embodiment" and "in various embodiments" of the present application are used repeatedly. This phrase generally does not refer to the same embodiment; it may also refer to the same embodiment. The terms "comprising," "having," and "including" are synonymous, unless the context dictates otherwise.
Although the present application has been described with reference to specific embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application, and all changes, substitutions and alterations that fall within the spirit and scope of the application are to be understood as being covered by the following claims.

Claims (10)

1. A magnetic random access memory storage unit with double free layers comprises a reference layer, a barrier layer, a first free layer and a covering layer which are arranged in a stacking mode, and is characterized in that a second free layer is arranged above the first free layer, a vertical magnetic coupling layer is arranged below the second free layer, and a magnetic damping barrier layer is arranged above the second free layer, wherein a magnetization vector in the second free layer is always vertical to the interface of the first free layer and is parallel to the magnetization vector in the first free layer;
the total structural thickness of the second free layer is 0.5-3.0nm, the composition material is Co/(Pt, Pd, Ni or Ir)/(CoFeB, CoB or FeB), (CoFeB, CoB or FeB)/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoB or FeB)/Co/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoFeB or FeB)/(Pt, Pd, Ni or Ir)/(CoFeB, CoB or FeB), Co/(Pt, Pd, Ni or Ir)/Co/(CoFeB, CoB or FeB), (CoFeB, CoB or FeB)/Co/(Pt, Pd, Ni or Ir)/Co/(CoFeB, CoFeB or FeB), (CoFeB, CoB or FeB)/X/Co/(Pt, Pd, Ni or Ir)/Co/CoFeB, CoB or FeB/(CoFeB, CoFeB or FeB)/X/Co/(Pt, Pd, Ni/Ir), pd, Ni or Ir), Co/(Pt, Pd, Ni or Ir)/Co/X/(CoFeB, CoB or FeB) multilayer structure; wherein X is W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru or Os.
2. The MRAM memory cell of claim 1, wherein the atomic percentage of B in FeB or CoB in the composition material of the second free layer is 15-40%; in the CoFeB alloy, Co: the atomic ratio of Fe is 1:3 to 3:1, and the atomic percentage of B is 15-40%.
3. The MRAM memory cell of claim 1, wherein the perpendicular magnetic coupling layer is configured to magnetically couple the first free layer to the second free layer such that a magnetization vector in the second free layer is always perpendicular to the first free layer interface and parallel to a magnetization vector in the first free layer; the perpendicular magnetic coupling layer is made of MgO, ZrO2, ZnO, Al2O3, GaO, Y2O3, SrO, Sc2O3, TiO2, HfO2, V2O5, Nb2O5, Ta2O5, CrO3, MoO3, WO3, RuO2, OsO2, TcO, ReO, RhO, IrO, SnO, SbO, MgZnO, MgBO, MgAlO or a combination of the above, and the thickness of the perpendicular magnetic coupling layer is 0.3-1.5 nm.
4. The MRAM memory cell of claim 1, wherein the damping barrier layer provides a perpendicular interface anisotropy to the magnetization vectors of all of the second free layers and reduces the magnetic damping coefficient of the entire film layer; the magnetic damping barrier layer is made of Mg, Zr, Zn, Al, Ga, Y, Sr, Sc, Ti, V, Nb, Cr, Os, Tc, Re, Rh, Ir, Sn, Sb, MgO, ZrO2, ZnO, Al2O3, GaO, Y2O3, SrO, Sc2O3, TiO2, HfO2, V2O5, Nb2O5, Ta2O5, CrO3, MoO3, WO3, RuO2, OsO2, TcO, ReO, RhO, IrO, SnO, SbO, MgZnO, MgBO and MgAlO or a combination thereof, and the thickness of the magnetic damping barrier layer is 0.5nm to 3.0 nm.
5. The MRAM memory cell of claim 1, wherein the barrier layer is made of a non-magnetic metal oxide such as MgO, MgZnO, MgBO, MgAlO or combinations thereof.
6. The MRAM memory cell of claim 1, wherein the first free layer is made of a CoFeB, CoFe/CoFeB, Fe/CoFeB, CoFeB/(W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru, Os, Ru, Rh, Ir, Pd, Pt)/CoFeB, Fe/CoFeB/(W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru, Os, Ru, Rh, Ir, Pd, Pt)/CoFeB or CoFe/CoFeB/(W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru, Os, Ru, Rh, Ir, Pd, Pt)/CoFeB structural stack.
7. The MRAM memory cell of claim 1, wherein the capping layer material is CoFeB, CoFeC, W, Mo, Mg, Nb, Ru, Hf, V, Cr or Pt.
8. The MRAM memory cell of claim 1, wherein the capping layer material is (W, Mo, Hf)/Ru or a Pt/(W, Mo, Hf)/Ru structure stack.
9. A magnetic random access memory comprising the memory cell of any one of claims 1-8, further comprising a bottom electrode, a seed layer, an antiparallel ferromagnetic superlattice layer, a lattice partition layer, a capping layer, and a top electrode, wherein the bottom electrode, the seed layer, the antiparallel ferromagnetic superlattice layer, the lattice partition layer, a reference layer, a barrier layer, a first free layer, a perpendicular magnetic coupling layer, a second free layer, a magnetic damping barrier layer, the capping layer, and the top electrode are stacked in this order.
10. The magnetic random access memory of claim 9, wherein the seed layer, the antiparallel ferromagnetic superlattice layer, the lattice partition layer, the reference layer, the barrier layer, the first free layer, the perpendicular magnetic coupling layer, the second free layer, the magnetic damping barrier layer, the capping layer, and the top electrode are deposited followed by an annealing operation at a temperature of 350 ℃ or more for at least 60 minutes.
CN201910860738.8A 2019-09-11 2019-09-11 Magnetic random access memory storage unit and magnetic random access memory Pending CN112490353A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201910860738.8A CN112490353A (en) 2019-09-11 2019-09-11 Magnetic random access memory storage unit and magnetic random access memory

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201910860738.8A CN112490353A (en) 2019-09-11 2019-09-11 Magnetic random access memory storage unit and magnetic random access memory

Publications (1)

Publication Number Publication Date
CN112490353A true CN112490353A (en) 2021-03-12

Family

ID=74920388

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201910860738.8A Pending CN112490353A (en) 2019-09-11 2019-09-11 Magnetic random access memory storage unit and magnetic random access memory

Country Status (1)

Country Link
CN (1) CN112490353A (en)

Citations (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1961377A (en) * 2004-05-11 2007-05-09 弘世科技公司 Spin barrier enhanced magnetoresistance effect element and magnetic memory using the same
US20080179699A1 (en) * 2007-01-30 2008-07-31 Magic Technologies, Inc. Novel magnetic tunnel junction (MTJ) to reduce spin transfer magnetization switching current
CN102216995A (en) * 2008-09-29 2011-10-12 希捷科技有限公司 Flux-closed stram with electronically reflective insulative spacer
US20130161770A1 (en) * 2011-12-21 2013-06-27 Hao Meng Magnetoresistive device and a method of forming the same
US20150102439A1 (en) * 2011-02-16 2015-04-16 Avalanche Technology, Inc. Magnetic random access memory with perpendicular enhancement layer
CN104868052A (en) * 2015-04-16 2015-08-26 上海磁宇信息科技有限公司 Adjustable vertical magneto-resistor element
CN106663467A (en) * 2014-07-01 2017-05-10 高通股份有限公司 Synthetic antiferromagnet (SAF) coupled free layer for perpendicular magnetic tunnel junction (P-MTJ)
CN107342359A (en) * 2016-04-29 2017-11-10 上海磁宇信息科技有限公司 A kind of magnetoresistive element suitable for working at high temperature
CN107403821A (en) * 2017-07-12 2017-11-28 北京航空航天大学 It is a kind of that there is double spacer and ferromagnetic or antiferromagnetic coupling multilayer film can be formed
US10008663B1 (en) * 2017-04-19 2018-06-26 Avalanche Technology, Inc. Perpendicular magnetic fixed layer with high anisotropy
CN108604632A (en) * 2016-01-28 2018-09-28 斯平转换技术公司 Memory cell with magnetic tunnel junction and thermal stability enhancement layer
CN108630805A (en) * 2017-03-24 2018-10-09 东芝存储器株式会社 Magnetic memory apparatus
WO2019005076A1 (en) * 2017-06-29 2019-01-03 Intel Corporation Magnetic tunneling junction devices with a carbon-doped magnet layer
WO2019005156A1 (en) * 2017-06-30 2019-01-03 Intel Corporation Spin orbit torque (sot) memory devices with enhanced switching capability and their methods of fabrication
CN110024150A (en) * 2016-12-30 2019-07-16 英特尔公司 Erect spin transfer torque memory (pSTTM) device with enhancing stability and forming method thereof
WO2019143052A1 (en) * 2018-01-17 2019-07-25 한양대학교 산학협력단 Memory device
CN110061126A (en) * 2018-01-19 2019-07-26 上海磁宇信息科技有限公司 A kind of magnetic RAM memory unit and its manufacturing method
CN111613720A (en) * 2019-02-25 2020-09-01 上海磁宇信息科技有限公司 Magnetic random access memory storage unit and magnetic random access memory

Patent Citations (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1961377A (en) * 2004-05-11 2007-05-09 弘世科技公司 Spin barrier enhanced magnetoresistance effect element and magnetic memory using the same
US20080179699A1 (en) * 2007-01-30 2008-07-31 Magic Technologies, Inc. Novel magnetic tunnel junction (MTJ) to reduce spin transfer magnetization switching current
CN102216995A (en) * 2008-09-29 2011-10-12 希捷科技有限公司 Flux-closed stram with electronically reflective insulative spacer
US20150102439A1 (en) * 2011-02-16 2015-04-16 Avalanche Technology, Inc. Magnetic random access memory with perpendicular enhancement layer
US20130161770A1 (en) * 2011-12-21 2013-06-27 Hao Meng Magnetoresistive device and a method of forming the same
CN106663467A (en) * 2014-07-01 2017-05-10 高通股份有限公司 Synthetic antiferromagnet (SAF) coupled free layer for perpendicular magnetic tunnel junction (P-MTJ)
CN104868052A (en) * 2015-04-16 2015-08-26 上海磁宇信息科技有限公司 Adjustable vertical magneto-resistor element
CN108604632A (en) * 2016-01-28 2018-09-28 斯平转换技术公司 Memory cell with magnetic tunnel junction and thermal stability enhancement layer
CN107342359A (en) * 2016-04-29 2017-11-10 上海磁宇信息科技有限公司 A kind of magnetoresistive element suitable for working at high temperature
CN110024150A (en) * 2016-12-30 2019-07-16 英特尔公司 Erect spin transfer torque memory (pSTTM) device with enhancing stability and forming method thereof
CN108630805A (en) * 2017-03-24 2018-10-09 东芝存储器株式会社 Magnetic memory apparatus
US10008663B1 (en) * 2017-04-19 2018-06-26 Avalanche Technology, Inc. Perpendicular magnetic fixed layer with high anisotropy
WO2019005076A1 (en) * 2017-06-29 2019-01-03 Intel Corporation Magnetic tunneling junction devices with a carbon-doped magnet layer
WO2019005156A1 (en) * 2017-06-30 2019-01-03 Intel Corporation Spin orbit torque (sot) memory devices with enhanced switching capability and their methods of fabrication
CN107403821A (en) * 2017-07-12 2017-11-28 北京航空航天大学 It is a kind of that there is double spacer and ferromagnetic or antiferromagnetic coupling multilayer film can be formed
WO2019143052A1 (en) * 2018-01-17 2019-07-25 한양대학교 산학협력단 Memory device
CN110061126A (en) * 2018-01-19 2019-07-26 上海磁宇信息科技有限公司 A kind of magnetic RAM memory unit and its manufacturing method
CN111613720A (en) * 2019-02-25 2020-09-01 上海磁宇信息科技有限公司 Magnetic random access memory storage unit and magnetic random access memory

Similar Documents

Publication Publication Date Title
US8758909B2 (en) Scalable magnetoresistive element
US9368176B2 (en) Scalable magnetoresistive element
CN111613720B (en) Magnetic random access memory storage unit and magnetic random access memory
US8604569B2 (en) Magnetoresistive element
US10953319B2 (en) Spin transfer MRAM element having a voltage bias control
US10439133B2 (en) Method and system for providing a magnetic junction having a low damping hybrid free layer
US20140203383A1 (en) Perpendicular magnetoresistive memory element
KR102188529B1 (en) Method and system for providing a bulk perpendicular magnetic anisotropy free layer in a perpendicular magnetic junction usable in spin transfer torque magnetic random access memory applications
US11114605B2 (en) Composite storage layer for magnetic random access memory devices
CN110676288A (en) Magnetic tunnel junction structure and magnetic random access memory
US20210343934A1 (en) Composite multi-stack seed layer to improve pma for perpendicular magnetic pinning
CN111816760A (en) Magnetic random access memory magnetic storage unit and forming method thereof
CN112864312A (en) Magnetic random access memory storage unit and magnetic random access memory
US11450466B2 (en) Composite seed structure to improve PMA for perpendicular magnetic pinning
US11043631B2 (en) Perpendicular magnetoresistive elements
CN114551716A (en) Magnetic tunnel junction free layer and magnetic tunnel junction structure with same
CN112490353A (en) Magnetic random access memory storage unit and magnetic random access memory
CN113140670A (en) Magnetic tunnel junction vertical antiferromagnetic layer and random access memory
CN112635655A (en) Magnetic tunnel junction covering layer and manufacturing process thereof
CN112490354A (en) Magnetic random access memory storage unit and magnetic random access memory
CN112635656A (en) Magnetic tunnel junction structure and magnetic random access memory
CN112864307A (en) Magnetic random access memory storage unit and magnetic random access memory
CN113013325B (en) Magnetic tunnel junction unit with leakage magnetic field balance layer and magnetic random access memory
CN113013322B (en) Magnetic tunnel junction unit structure with vertical anisotropic field enhancement layer
CN112652702B (en) Magnetic tunnel junction structure of magnetic random access memory

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
RJ01 Rejection of invention patent application after publication
RJ01 Rejection of invention patent application after publication

Application publication date: 20210312