KR101739640B1 - Multilayered magnetic thin film stack and nonvolatile memory device having the same - Google Patents

Abstract

The present invention relates to a multi-layer magnetic thin film stack and a non-volatile magnetic memory device using magnetic tunneling junction (MTJ). A multilayer magnetic thin film stack according to an embodiment of the present invention includes a tunneling barrier layer, a magnetization pinned layer on a first side of the tunneling barrier layer, and a magnetic free layer on a second side opposite to the first side of the tunneling barrier layer And a magnetic tunneling junction including a magnetic tunneling junction. In one embodiment, at least one of the magnetically fixed layer and the magnetic free layer has a body-centered cubic structure adjacent to the tunneling barrier layer and includes a CoFe-based first magnetic layer containing cobalt (Co) and iron (Fe); A second magnetic layer interlayer-magnetically exchange-coupled with the CoFe-based magnetic layer; And a first layer including a laminated structure of a tantalum (Ta) layer adjacent to the CoFe-based magnetic layer and a ruthenium (Ru) layer adjacent to the second magnetic layer, the first layer being disposed between the first magnetic layer and the second magnetic layer. And a composite spacer layer.

Description

[0001] The present invention relates to a multilayer magnetic thin film stack and a nonvolatile memory device including the same,

The present invention relates to memory technology, and more particularly, to a multi-layer magnetic thin film stack and a non-volatile memory device including the same.

A magnetic random access memory (MRAM or MRAM) is a nonvolatile solid-state magnetic memory device that utilizes a giant magnetoresistance effect or a tunneling magnetoresistance effect based on a spin-dependent conduction phenomenon peculiar to a nano-magnetic material. The MRAM has attracted a great deal of attention recently because it is faster than other phase change memories (PcRAMs) or resistive memories (ReRAM) and has excellent durability according to repeated use.

In order to realize the MRAM device, the spin transfer torque magnetic random access memory (STT-MRAM), which is most actively studied, is a next-generation memory capable of high-speed operation, excellent power efficiency, and high integration. The STT-MRAM includes a magnetic tunnel junction (MTJ) structure having a structure in which one tunneling barrier layer is interposed between two magnetic thin films. In the MTJ structure, perpendicular magnetic anisotropy (or PMA) has a lower switching current density for magnetization reversal and higher thermal stability than in-plane magnetic anisotropy, .

The PMA can be obtained by intrinsic magnetocrystalline anisotropy of one or more magnetic layers or by anisotropy due to interfacial effects between the layers. Generally, when a high recording current is required due to intrinsic crystalline magnetic anisotropy and a high production temperature of 500 DEG C or more is required to obtain the crystallinity of the magnetic thin film, an interface that can be achieved through a multilayer thin film laminated structure Anisotropy due to the effect is preferable. The multilayer thin film laminate structure can be formed by a conventional sputtering process and can be manufactured at a low temperature of 300 ° C or less, so that the manufacturing process is advantageous.

However, the vertical magnetization method using the interfacial anisotropy generally has a problem of low post-annealing safety in which vertical magnetization characteristics are deteriorated in a subsequent process involving heat. This has a direct effect on the recording of reliable data and the data retention (data retention), which is required to be improved.

A problem to be solved by the present invention is to provide a reliable multi-layered magnetic thin film stack having high interfacial anisotropy and improved post-annealing stability, thereby reliably recording data and retaining data for a long period of time.

Another object of the present invention is to provide a nonvolatile memory device including the multi-layer magnetic thin film stack having the above-described advantages.

According to an aspect of the present invention, there is provided a multi-layer magnetic thin film stack including a tunneling barrier layer, a magnetoresistance layer on a first surface of the tunneling barrier layer, And a magnetic tunneling junction comprising a self-free layer on two sides. At least one of the magnetically fixed layer and the magnetic free layer has a body-centered cubic structure adjacent to the tunneling barrier layer and includes a CoFe-based first magnetic layer containing cobalt (Co) and iron (Fe); A second magnetic layer interlayer-magnetically exchange-coupled with the CoFe-based magnetic layer; And a first layer including a laminated structure of a tantalum (Ta) layer adjacent to the CoFe-based magnetic layer and a ruthenium (Ru) layer adjacent to the second magnetic layer, the first layer being disposed between the first magnetic layer and the second magnetic layer. And a composite spacer layer.

In one embodiment, the tunneling barrier layer is Al ₂ O _3, MgO, TiO _2, AlN, RuO, SrO, SiN, CaO _x, HfO _2, Ta ₂ O _5, ZrO _2, SiC, SiO _2, SiO _x N _y , or a laminated structure of two or more of them. The CoFe-based first magnetic layer may include cobalt-iron (CoFe), cobalt-iron-boron (CoFeB), or a laminated structure of two or more of them.

The second magnetic layer may include a multilayer structure in which a nonmagnetic metal layer and a cobalt-containing magnetic layer are alternately stacked at least once. In this case, the non-magnetic metal layer may be at least one selected from the group consisting of Pt, Rh, Hf, Pd, Ta, Os, Ge, Ir, (Au), and silver (Ag), or an alloy thereof. The cobalt-containing magnetic layer may include a pure cobalt layer, a CoZr alloy layer, a CoFe alloy layer, a CoFeB alloy layer, or a laminated structure thereof.

In one embodiment, the first magnetic layer and the second magnetic layer are capable of anti-parallel interlayer exchange coupling. The tantalum layer of the first composite spacer layer may have a thickness of 0.2 nm to 0.6 nm and the ruthenium layer may have a thickness of 0.2 nm to 1.2 nm. Further, the thickness of the ruthenium layer may be in the range of 0.6 to 0.9 nm.

And the other of the magnetically fixed layer and the magnetic free layer may have a body-centered cubic structure adjacent to the other surface of the tunneling barrier layer in contact with the first magnetic layer. A CoFe-based third magnetic layer containing cobalt (Co) and iron (Fe); A fourth magnetic layer interlayer-magnetically exchange-coupled with the CoFe-based magnetic layer; And a second layer including a laminated structure of a tantalum (Ta) layer adjacent to the CoFe-based magnetic layer and a ruthenium (Ru) layer adjacent to the second magnetic layer, the layer being disposed between the CoFe-based third magnetic layer and the fourth magnetic layer. And a composite spacer layer.

According to another aspect of the present invention, there is provided a multilayer magnetic thin film stack including: a first magnetic layer having a body-centered cubic structure with a (001) orientation grown face; A second magnetic layer having an outermost crystal growth surface; And a composite spacer layer of a tantalum layer on the first magnetic layer side and a ruthenium layer on the second magnetic layer side inserted between the first magnetic layer and the second magnetic layer. The first magnetic layer and the second magnetic layer can perform exchange coupling between antiparallel layers.

The tantalum layer of the composite spacer layer may have a thickness of 0.2 nm to 0.6 nm and the ruthenium layer may have a thickness of 0.2 nm to 1.2 nm. The thickness of the ruthenium layer is in the range of 0.6 to 0.9 nm.

The multi-layer magnetic thin film stack further includes a template layer for crystallization on the growth surface of the (001) orientation by heat treatment of the first magnetic layer on a surface opposite to the surface of the first magnetic layer in contact with the composite spacer layer can do. The template layer may comprise MgO (001). The multi-layer magnetic thin film stack may have perpendicular anisotropy.

The first magnetic layer may include cobalt-iron (CoFe), cobalt-iron-boron (CoFeB), or a laminated structure of two or more of them. The second magnetic layer may include a multilayer structure in which a platinum (Pt) layer and a cobalt (Co) magnetic layer are alternately stacked at least once.

According to an embodiment of the present invention, there is also provided a nonvolatile memory device including the multilayer magnetic thin film stack.

According to the embodiment of the present invention, by using a composite spacer layer having a laminated structure of a tantalum layer and a ruthenium layer, a CoFe-based magnetic layer having a body-centered cubic structure with excellent tunneling magnetoresistive effect, a nonmagnetic metal layer And a multilayer magnetic layer including at least one unit laminated structure including a cobalt-containing magnetic layer, a high post-thermal stability, a strong vertical magnetic anisotropy, and a high tunneling magnetoresistance effect are secured, A multilayer magnetic thin film stack having recording of data with high data retention characteristics and high data retention characteristics can be provided. Further, according to the embodiment of the present invention, it is possible to structurally decouple the first magnetic layer having the body-centered cubic crystal structure and the second magnetic layer having the best-accuracy crystal structure, and to magnetically couple these magnetic layers A multilayer magnetic thin film stack in which characteristics of the magnetic structure can be easily controlled can be provided.

Further, according to another embodiment of the present invention, a nonvolatile memory element including a multilayer magnetic thin film stack having the above-described advantages can be provided.

1A and 1B are cross-sectional views of a memory cell of a nonvolatile memory device including a magnetization perpendicular to the plane (MTJ) magnetic tunneling junction (MTJ) according to an embodiment of the present invention, respectively.
2A-2D are cross-sectional views illustrating magnetic tunneling junctions in accordance with various embodiments of the present invention.
3A is a cross-sectional view showing a multi-layer magnetic thin film stack including a composite spacer layer according to an embodiment of the present invention, and FIG. 3B is a cross-sectional view illustrating a multilayer magnetic thin film stack according to a comparative example in which a Ru layer is inserted instead of a composite spacer layer Sectional view showing a thin film stack.
4A to 4C are m - H loop graphs in an out-of-plane ( H _⊥ , ◯) plane ( H _∥ , □) of a multi-layer magnetic thin film stack according to an embodiment of the present invention, It is an m - H loop graph of a magnetic thin film stack.
FIGS. 5A and 5B are graphs showing magnetization values m _s and m _r of the tantalum layer of the multi-layer magnetic thin film stack including the composite spacer according to the embodiment of the present invention, and the magnetization values m _s and m _r of the cobalt-iron- the effective perpendicular magnetic anisotropy energy density of the CoFeB) _CoFeB K and a graph of the inter-layer exchange-coupling energy density J _ex value between the first magnetic layer and second magnetic layer.
Figure 6 is an out-of-plane ( H _⊥ , ∘) and in-plane ( H _∥ , □) m - H loop graph of a multi-layer magnetic thin film stack 2000 comprising a composite spacer layer according to an embodiment of the invention.
Figs. 7A and 7B are enlarged views of the minor loop portion of the out-of-plane loop measured in regions b and c of Fig. 6, respectively.
8A and 8B show the interlayer exchange coupling energy ( -J _ex or -j _ex ) according to the thickness of the ruthenium layer of the multi-layer magnetic thin film stack according to the embodiment of the present invention including the composite spacer.
9 is a block diagram illustrating an electronic system including a non-volatile memory device in accordance with one embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention are described in order to more fully explain the present invention to those skilled in the art, and the following embodiments may be modified into various other forms, The present invention is not limited to the embodiment. Rather, these embodiments are provided so that this disclosure will be more faithful and complete, and will fully convey the scope of the invention to those skilled in the art.

In the drawings, the thickness and size of each layer are exaggerated for convenience and clarity of description, and the same reference numerals refer to the same elements in the drawings. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" include singular forms unless the context clearly dictates otherwise. Also, " comprise "and / or" comprising "when used herein should be interpreted as specifying the presence of stated shapes, numbers, steps, operations, elements, elements, and / And does not preclude the presence or addition of one or more other features, integers, operations, elements, elements, and / or groups.

Although the terms first, second, etc. are used herein to describe various elements, components, regions, and / or portions, these elements, components, regions, and / or portions should not be limited by these terms. It is self-evident. These terms are only used to distinguish one member, component, region or portion from another region or portion. Accordingly, the first member, component, region or portion described below may refer to a second member, component, region or portion without departing from the teachings of the present invention.

Further, in the case where some layers are formed or arranged on another layer, an intermediate layer may be formed or arranged between these layers. Similarly, even if some materials are adjacent to another material, there may be an intermediate material between these materials. Conversely, when a layer or material is referred to as being "directly" or "directly" formed or disposed on another layer or material, or "directly" It should be understood that there is no intermediate material or layer between the layers.

Hereinafter, embodiments of the present invention will be described with reference to the drawings schematically showing ideal embodiments of the present invention. In the drawings, for example, the size and shape of the members may be exaggerated for convenience and clarity of explanation, and in actual implementation, variations of the illustrated shape may be expected. Accordingly, embodiments of the present invention should not be construed as limited to any particular shape of the regions shown herein.

In this specification, the term "substrate" is not limited to a bulk base structure such as silicon, silicon-on-insulator (SOI) or silicon-on-sapphire (SOS), and includes semiconductor layers, doped or undoped semiconductor layers, A modified semiconductor layer or non-semiconductor layer may also be referred to. Further, the term semiconductor is not limited to a silicon-based material, but may be a III-V semiconductor material such as a carbon, a polymer, or a silicon-germanium, a germanium and a gallium-gallium-based compound material, a II- Collectively. The term non-semiconductor may refer to an insulating ceramic material, a metal material, or a polymer material, but is not limited thereto.

1A and 1B illustrate a memory cell 1000A, 100B, and 100B of a nonvolatile memory device including a magnetization perpendicular to the plane (MPP) magnetic tunneling junction (MTJ) 100A, 100B according to an embodiment of the present invention, 1000B.

Referring to FIG. 1A, a memory cell 1000A is an information storage member and can constitute a unit storage node of non-volatile magnetic memory devices 1000A. At one end of the magnetic tunneling junction 100A of the memory cell 1000A, a selection element, for example, a transistor TR, for selecting a memory cell can be coupled. The gate of the transistor TR may be electrically coupled to the first wiring, for example, the word line WL. The other end of the magnetic tunneling junction 100A may be connected to, for example, the bit line BL. The memory cell 1000A may further include suitable electrodes EL1 and EL2 coupled to the word line WL and the bit line BL. The transistor TR is a non-limiting example of a selection device and may be a field effect transistor or a bipolar transistor. Alternatively, the selection element may be a graphene or a nano-switching element using a nano phenomenon.

Referring to FIG. 1B, in another embodiment, a selection device for selecting memory cell 1000B may include a diode DI coupled thereto in series. Diode DI shown in FIG. 1B illustrates a PN junction diode. In another embodiment, the diode DI may be replaced by or in place of the PN junction diode DI, any diode that can achieve cell selectivity according to the potential difference between the word line WL and the bit line BL. A diode whose polarity is inverted, or a bidirectional diode with bi-directional rectification characteristics for a driving scheme such as unidirectional switching. In another embodiment, the diode DI may be a pin (p type) coupled with a Schottky barrier diode, a zener diode, or an intrinsic semiconductor layer for high capacity memory devices, semiconductor-intrinsic semiconductor-p type semiconductor) junction diode, or a p-type semiconductor-intrinsic semiconductor-metal (pim) diode through a junction with a metal layer.

The bit line BL and the word lines WL shown in FIGS. 1A and 1B may have a plurality of orthogonal stripe patterns extending in different directions, for example, The cell array in which the magnetic tunneling junctions 100A and 100B are disposed can be formed. In one embodiment, the memory cells may have a cross point array structure that satisfies the degree of integration of 4F ² . The array of such memory cells is not limited to a two-dimensional planar structure, but may be a three-dimensional structure in which two or more horizontal arrays are stacked in the vertical direction of the substrate, or a three-dimensional structure obtained by forming a channel layer extending in the vertical direction of the substrate .

The magnetic tunneling junctions 100A and 100B that constitute the memory cell may include a tunneling barrier layer 110, a magnetization pinned layer 120, and a magnetic free layer 130. The stacking order of the magnetically fixed layer 120 and the magnetic free layer 130 may be reversed with each other across the tunneling barrier layer 110, as shown in FIGS. 1A and 1B. Directional arrow B indicates that the free layer 130 is magnetized parallel or anti-parallel to the magnetization direction of the magnetostatic layer 120 It can be magnetized. In one embodiment, a change in the magnetization direction of the self-free layer 130 may be achieved by controlling the direction of the tunneling current with the spin torque flowing along the magnetic tunneling junctions 100A and 100B.

The magnetostatic layer 120 and the magnetic free layer 130 have perpendicular magnetic anisotropy (PMA). Although not shown, a symmetrical magnetic tunneling junction may be provided in which two tunneling barrier layers and a magnetization pinning layer are additionally stacked on the magnetic free layer 130 to sandwich the magnetization free layer 130 and the two magnetization pinning layers are opposed to each other have. This symmetrical magnetic tunneling junction has the advantage that the direction of the current for programming and erasing can be unidirectional.

2A-2D are cross-sectional views illustrating magnetic tunneling junctions 200A, 200B, 200C, and 200D in accordance with various embodiments of the present invention.

2A, a magnetic tunneling junction 200A includes a tunneling barrier layer 210, a magnetically fixed layer 220 on a first surface 210a of the tunneling barrier layer 210, Free layer 230 on the two-sided surface 210b. The stacking order of the magnetization fixed layer 220 and the magnetic free layer 230 with the tunneling barrier layer 210 therebetween may be reversed. The magnetostatic layer 220 and the magnetic free layer 230 may each comprise a single magnetic layer, a laminate of different types of magnetic layers, or a laminate of a magnetic layer and a nonmagnetic layer. This will be described later.

The tunneling barrier layer 210, for example, Al ₂ O _3, MgO, TiO _2, AlN, RuO, SrO, SiN, CaO _x, HfO _2, Ta ₂ O _5, ZrO _2, SiC, SiO _2, SiO _x N _y , or two or more of these laminated thin films. Preferably, the tunneling barrier layer 210 may comprise a (001) oriented MgO layer of NaCl type (hereinafter referred to as MgO (001) layer). The MgO (001) layer may be monocrystalline or polycrystalline. After the layers constituting the magnetic tunneling junction 200A are stacked, the magnetic free layer 230 or the magnetic layer Can function as a template layer for inducing crystallization in a body-centered cubic structure.

In one embodiment, the magnetostatic layer 220 includes a first magnetic layer 221, a second magnetic layer 222 and a composite spacer layer 223 between these magnetic layers 221 and 222, . The first magnetic layer 221 may be a magnetic layer having a (001) crystal growth surface with a body centered cubic (bcc) structure to have strong PMA characteristics. The magnetic layer having the bcc structure may be, for example, a CoFe-based magnetic layer. The CoFe-based magnetic layer may include cobalt-iron (CoFe), cobalt-iron-boron (CoFeB), or a laminated structure of two or more of them. The cobalt-iron-boron magnetic layer may be amorphous when formed by a sputtering process. However, when the multi-layer magnetic thin film stack 200A is subjected to a post-heat treatment or a heat treatment by heat load accompanying a subsequent process such as a wiring process Boron magnetic layer can be crystallized into a CoFe compound layer of a bcc structure while boron which is small in size diffuses into an adjacent layer, the amorphous cobalt-iron- Conditions can be formed. In this case, when the tunneling barrier layer 210 is, for example, a MgO layer having a (001) structure, the first magnetic layer made of cobalt-iron- (001) crystallization with the diffusion of boron to form a first magnetic layer 221 including a cobalt-iron layer having a bcc structure. When a magnetic layer made of cobalt-iron-boron is formed on the other surface 210b of the tunneling barrier layer 210 and a magnetic layer including a CoFe layer having a bcc (001) structure is formed through a suitable heat treatment A magnetic tunnel junction with a maximum tunneling magnetoresistance effect with vertical anisotropy based on interface anisotropy can be provided.

In one embodiment, in the CoFe-based magnetic layer, the atomic ratio Co: Fe may be in the range of 1: 5 to 7: 3. Preferably, in the atomic ratio, the number of moles of Fe is larger than the number of moles of Co. This is because as the number of moles of Fe is larger than the number of moles of Co, a high spin polarization ratio can be obtained while securing a stable bcc structure in the CoFe-based magnetic layer.

The second magnetic layer 222 may include a ferromagnetic layer or an antiferromagnetic layer having high perpendicular magnetic anisotropy and excellent thermal stability. The second magnetic layer 222 is magnetically coupled with the first magnetic layer to form a synthetic ferri-magnetic layer or a synthetic anti-ferro-magnetic layer having a large magnetic tunnel resistance effect and improved thermal stability. ) Can be implemented. In particular, the implementation of the synthetic ferrimagnetic layer is important for low power and ultra-high integration of spin-transfer switching of memory devices using magnetic tunneling junctions.

Since the second magnetic layer 222 is structurally decoupled from the first magnetic layer 221 by the composite spacer layer 223 as described later, the crystal structure of the second magnetic layer 222 is formed in the first magnetic layer 221 It does not affect. Therefore, the second magnetic layer 222 is not limited to a specific crystal structure but may be any crystal structure capable of enhancing the perpendicular anisotropy of the magnetic tunneling junction 200A, for example, a close-packed growth plane For example, a single magnetic layer preferentially oriented to a (111) plane or a (110) plane, a laminate of different kinds of magnetic layers, or a laminate of a magnetic layer and a nonmagnetic layer.

The first magnetic layer 221 may include a ferromagnetic material, and the second magnetic layer 222 may include an antiferromagnetic material. The anti-ferromagnetic material, for example, may include any of PtMn, IrMn, MnO, MnS, MnTe, MnF _2, FeCl _2, FeO, CoCl _2, CoO, NiCl _2, NiO one or more than two. The structures of the first magnetic layer 221 and the second magnetic layer 222 are exemplary and the composite spacer layer 223 structurally debondes the first magnetic layer 221 and the second magnetic layer 222, A multilayer magnetic thin film stack including a magnetic tunneling junction having excellent TMR characteristics and perpendicular anisotropy can be provided since the magnetic layer 221 and the second magnetic layer 222 can be strongly magnetically coupled.

The composite spacer layer 223 has a laminated structure of a tantalum layer 223a and a ruthenium layer 223b. The tantalum layer 223a is adjacent to the first magnetic layer 221 side having the crystal growth surface of the bcc structure and the ruthenium layer 223b is adjacent to the second magnetic layer 222 side having a crystal structure different from the bcc structure. Structural debonding is performed between the first magnetic layer 221 and the second magnetic layer 222 by the tantalum layer 223a. However, since the magnetic decoupling occurs between the first magnetic layer 221 and the second magnetic layer 222 only with the hardness layer 223a, the magnetostatic layer 220 having sufficient vertical anisotropy can not be obtained. However, the drawback of this tantalum layer 223a is supplemented by the ruthenium layer 223b which induces strong magnetic coupling between the first magnetic layer 221 and the second magnetic layer 222. [ This is obtained by the interlayer exchange coupling (IEC) effect by the ruthenium layer 223b in the composite spacer layer 223, which will be described in detail later.

In one embodiment, the tantalum layer 223a of the composite spacer layer 223 has a thickness of 0.2 nm to 0.6 nm. When the thickness of the tantalum layer 223a is less than 0.2 nm, it is difficult to induce the (001) orientation of the first magnetic layer 221. When the thickness of the tantalum layer 223a is more than 0.6 nm, And the interlayer exchange coupling characteristics of the second magnetic layer 222 are lowered.

The ruthenium layer 223b may have a thickness of 0.2 nm to 1.2 nm. The minimum value of the thickness of the ruthenium layer 223b of the composite spacer layer 223 may be reduced to 0.2 nm according to embodiments of the present invention. In this region, a pinhole is usually formed in the ruthenium layer 223b, so that the IEC effect is hardly exhibited. However, the thickness of the ruthenium layer 223b, which is reinforced by the adjacent tantalum layer 223a and exhibits the IEC effect, Or practical advantages. When the thickness t is 0.8 nm _Ru layer of tantalum _Ta the thickness t of 0.4 nm (223a) and a ruthenium layer (223b), IEC absolute value reaches a maximum value of ^{7.9 × 10 -2 erg / cm- 2} . Preferably, the thickness of the ruthenium layer 223b is in the range of 0.3 nm to 0.9 nm, more preferably 0.4 nm to 0.9 nm, in which antiparallel interlayer exchange coupling capable of obtaining a synthetic ferrimagnet is generated as described later , More preferably within the range of 0.6 nm to 0.9 nm in which stable interlayer exchange coupling is obtained even at 375 DEG C or higher.

According to another embodiment of the present invention, the second magnetic layer 222 may include a multi-layer structure. For example, as shown in FIG. 2B, the second magnetic layer 222 has a unit laminated structure of a nonmagnetic metal layer (hereinafter, NM) 222a and a cobalt (Co) magnetic layer 222b at least And may include a [NM / Co] _N multi-layer structure stacked one or more times. The [NM / Co] _N multi-layer structure may have a superlattice structure of a non-magnetic metal layer 222a and a cobalt-containing magnetic layer 223b.

In one embodiment, the nonmagnetic metal layer 222a comprises platinum Pt and the cobalt-containing magnetic layer 222b comprises [Pt / Co] _N or [Co / Pt] _N , Layered structure which is an integer of 1 or more as the number of times of lamination. The N may be in the range of 1 to 20 or less. In another embodiment, the non-magnetic metal layer 222a may be formed of at least one of Rh, Rh, (Au), and silver (Ag), or an alloy thereof. In another embodiment, the cobalt-containing magnetic layer 222b may include a cobalt-containing alloy layer such as a CoZr alloy layer, a CoFe alloy layer, a CoFeB alloy layer, or a laminated structure thereof.

The [NM / Co] _N multilayer structure 222 can be easily formed by sputtering when the finest grown surface is the fcc (111) plane, and can also be formed by a high perpendicular magnetic anisotropy (PMA) due to interfacial anisotropy And at the same time has high thermal stability, it is very important for the implementation of nonvolatile memory cells of highly integrated magnetic memory. In addition, since it has control parameters based on various selectivities such as the thickness of the constituent layers of the multi-layer structure, the number of stacking N, or the kind of the non-magnetic metal layer, it is easy to control the characteristics such as the magnitude of the magnetic susceptibility. For example, by controlling the thickness of the [Pt / Co] _N multilayer structure, temperature durability can be obtained in which the PMA characteristic is maintained even at a temperature higher than 300 ° C. For example, in the [Pt / Co] _N multilayer structure 222, as disclosed in Korean Patent Application No. 10-1287370 of the present applicant (the entire disclosure of which is incorporated herein by reference) The heat resistance of the PMA characteristics can be improved by making the thickness of the cobalt layer 222b, which is a magnetic layer, larger than the thickness of the platinum layer 222a. For example, the thickness of the cobalt layer 222b is 0.4 to 0.5 nm and the thickness of the platinum layer 222a is 0.2 nm. The [NM / Co] _N multilayer structure 222, preferably the [Pt / Co] _N multilayer structure 222 having an inverted structure can maintain the PMA characteristic even at around 500 ° C, The entire PMA characteristic can be maintained.

The second magnetic layer 222 having the [Pt / Co] _N multilayer structure has the highest density of the fcc (111) plane, but the second magnetic layer 222 having the [Pt / Co] _N multilayer structure and the The composite spacer layer 223 interposed between the first magnetic layers 221 is structurally debonded between the first magnetic layer 221 and the second magnetic layer 222. Accordingly, the first magnetic layer 221 is not influenced by the crystal structure of the second magnetic layer 222, and can be dominantly influenced by the MgO (001) tunneling barrier layer 210, which is another adjacent layer.

A second magnetic layer 222 / composite spacer layer 223 having a [Pt / Co] _N multi-layer structure / a first magnetic layer 221 / MgO (001) including an amorphous CoFeB layer in order to form a magnetic tunneling junction. ) Tunneling barrier layer 210 / a magnetic free layer 230 comprising an amorphous CoFeB layer. The multilayer magnetic thin film stack 200B is formed such that the amorphous first magnetic layer 221 undergoes the template effect only by the MgO (001) tunneling barrier layer 210 due to the structural decoupling effect of the composite spacer layer 223 during post- And may not be influenced by the fcc (111) plane of the second magnetic layer 222. Thus, the first magnetic layer 221 including the amorphous CoFeB layer is stably crystallized in the (001) bcc structure, and the magnetic free layer 230 including the CoFeB layer is also stabilized in the (001) bcc structure, Can be maximized.

2B, when the layer stabilized with the (001) bcc structure is a CoFe magnetic layer 221, the second magnetic layer having a [Pt / Co] _N multilayer structure having excellent thermal stability and strong PMA characteristics, The ferromagnetic layer 222 may be formed of a synthetic ferrimagnetic layer by antiparallel IEC (AP-IEC) together with the first magnetic layer 221 including CoFe or CoFeB having a (001) bcc structure. The synthetic ferrimagnetic layer can provide a memory device capable of low power driving by reducing or suppressing stray fields occurring in the stationary magnetic layer 220. [ A synthetic ferrimagnetic layer according to an embodiment of the present invention is preferred because the stray field can adversely affect especially in the case of highly integrated memory cells on the nanometer scale. This will be described later in detail through experimental examples.

Referring again to FIG. 2A, a magnetic free layer 230 is further formed on a second surface 210b opposite to the first surface 210a of the tunneling barrier layer 210 to form a magnetic tunneling junction 200A , 200B may be provided. The magnetic free layer 230 may include a ferromagnetic material. The ferromagnetic material may be, for example, CoFe, NiFe, CoNiFe or a doped alloy such as Co, CoNiFeX, and CoFeX, wherein X is B, Cu , Re, Ru, Rh, Hf, Pd, Pt, Ta, Os, Ge, Ir, Au, Ag and C or a combination thereof. Alternatively, the ferromagnetic material may comprise a semi-metallic ferromagnetic material such as Fe ₃ O ₄ , CrO ₂ , NiMnSb, PtMnSb and BiFeO. These materials are illustrative, and the present invention is not limited thereto. For example, the magnetic free layer 230 is Gd, Dy, Y ₃ Fe ₅ O _12, MnSb, other well-known of the ferromagnetic material or the above-described materials such as MnAs B, Cu, Re, Ru, Rh, Hf, Pd, Pt, Os, Ir, Au and Ag, and C, or a combination thereof.

The magnetic free layer 230 including the CoFe-based magnetic layer having the bcc (001) structure is obtained through post-heat treatment by the template effect of the MgO (001) tunneling barrier layer 210 in the same manner as the first magnetic layer 221 . In some embodiments, both the magnetic free layer 230 and the first magnetic layer 221 may be CoFe (001), which has the advantage of achieving a high tunneling magneto-resistance (TMR) .

2C, a magnetic tunneling junction 200C according to another embodiment includes a tunneling barrier layer 210, a magnetization pinning layer 220 on a first side 210a of the tunneling barrier layer 210, Free layer 230 on the second side 210b of the second layer 210. [ Each of the magnetically fixed layers 220 may include a single magnetic layer, a laminate of different types of magnetic layers, or a laminate of a magnetic layer and a non-magnetic layer.

The magnetic free layer 230 may include a composite spacer layer 233 for structural demagnetization and magnetic coupling between the first magnetic layer 231, the second magnetic layer 232 and the magnetic layers 231 and 232. The first magnetic layer 231 may include a magnetic layer having a bcc (001) structure. As described above, the first magnetic layer 231 may include a ferromagnetic material. For example, the first magnetic layer 231 of the bcc (001) structure may include cobalt-iron (CoFe), cobalt-iron-boron (CoFeB), or a laminated structure thereof. Preferably, the first magnetic layer 231 may include cobalt-iron-boron (CoFeB).

The second magnetic layer 232 may be any layer magnetically coupled to the first magnetic layer 232. The second magnetic layer 232 can be structurally decoupled from the first magnetic layer 231 by the composite spacer layer 233. It is to be noted that the first magnetic layer 231 and the second magnetic layer 232 may form a synthetic ferrimagnetic layer or a synthetic antiferromagnetic layer. The composite spacer layer 233 may include a laminated structure of a tantalum layer 233a adjacent to the first magnetic layer 231 and a ruthenium layer 233b adjacent to the second magnetic layer 232, And has a reversed structure at the time of contrast.

In one embodiment, the second magnetic layer 232 is formed of a cobalt (Co) -containing magnetic layer and a nonmagnetic metal layer (hereinafter referred to as " NM ") having perpendicular anisotropy due to the interfacial effect as described with reference to FIG. Layer structure in which a unit laminated structure having a lattice structure is laminated at least one time. For example, the second magnetic layer 232 may be formed by forming the non-magnetic metal layer in a multilayered structure of [Pt / Co] _N or [Co / Pt] _N (where N is an integer of 1 or more, . ≪ / RTI > As described above, the multi-layer structure [Pt / Co] _N may have a reversed structure in which the thickness of the Co thin film is larger than the thickness of the Pt thin film, and preferably, the platinum layer 223a is first deposited, Containing magnetic layer 223b on the magnetic layer 223a.

In another embodiment, the magnetically free layer 230 may have a stacked ferromagnetic structure in which an antiferromagnetic layer is exchange-coupled to the ferromagnetic layer and the ferromagnetic layer to form a synthetic ferrimagnetic layer or a synthetic antiferromagnetic layer. In addition, the first magnetic layer 231 may include a ferromagnetic material, and the second magnetic layer 232 may include an anti-ferromagnetic material or a synthetic antiferromagnetic material. Alternatively, the first magnetic layer 231 may include an antiferromagnetic material, and the second magnetic layer 232 may include a ferromagnetic material. In this case, the composite spacer layer 233 structurally disengages the first magnetic layer 231 and the second magnetic layer 232, but at the same time, magnetically couples these layers. In another embodiment, at least one of the first magnetic layer 231 and the second magnetic layer 232 of the magnetic free layer 230 may comprise a soft magnetic layer.

In one embodiment, when the first magnetic layer 231 is formed on the second surface 210b of the MgO (001) tunneling barrier layer 210, the first surface 210a opposite to the second surface 210b A third magnetic layer 220 may be further formed to provide a magnetic tunneling junction 200C. The third magnetic layer 220 may include a ferromagnetic layer having a (001) bcc structure similarly to the first magnetic layer 231. With respect to the third magnetic layer 220, reference may be had to the foregoing disclosure of the first magnetic layer 231. [

Referring to FIG. 2D, the multilayer magnetic thin film stack 200D includes a tunneling insulating layer 210, a magnetization pinning layer 220, and a magnetic free layer 230. The magnetically fixed layer 220 and the magnetic free layer 230 are reversed to form the magnetically fixed layer as shown in the upper part of the tunneling insulating layer 210 and a magnetic free layer is formed under the tunneling insulating layer 220 . The tunneling barrier layer 210, for example, Al ₂ O _3, MgO, TiO _2, AlN, RuO, SrO, SiN, CaO _x, HfO _2, Ta ₂ O _5, ZrO _2, SiC, SiO _2, SiO _x N _y , or two or more of these laminated thin films. Preferably, the tunneling barrier layer 220 may comprise a MgO (001) layer of the NaCl type.

In one embodiment, the magnetostatic layer 220 may include a first magnetic layer 221 separated by a first composite spacer layer 223 and a second magnetic layer 222 of a multi-layered structure [Pt / Co] _N . The magnetic free layer 230 may also include a third magnetic layer 231 separated by the second composite spacer layer 233 and a fourth magnetic layer 232 of a multi-layered structure [Pt / Co] _N. Although not shown, the first magnetic layer 221 separated by the first composite spacer layer 223 and the second magnetic layer 222 of the multi-layered structure [Pt / Co] _N constitute a magnetic free layer, The third magnetic layer 231 separated by the second composite spacer layer 233 and the fourth magnetic layer 232 of the multi-layer structure [Pt / Co] _N may constitute a magnetically fixed layer.

The first magnetic layer 221 and the third magnetic layer 231 may be made of CoFe, NiFe, CoNiFe or a doped alloy such as CoX, CoNiFeX, CoFeX where X is B, Cu, Re, Ru, Rh, Hf, Pd, Pt, Ta, Os, Ge, Ir, Au, Ag, and C, or combinations thereof). Alternatively, the ferromagnetic material may comprise a semi-metallic ferromagnetic material such as Fe ₃ O ₄ , CrO ₂ , NiMnSb, PtMnSb and BiFeO. These materials are illustrative, and the present invention is not limited thereto. For example, the magnetic free layer 230 is Gd, Dy, Y ₃ Fe ₅ O _12, MnSb, other well-known of the ferromagnetic material or the above-described materials such as MnAs B, Cu, Re, Ru, Rh, Hf, Pd, Pt, Os, Ir, Au and Ag, and C, or a combination thereof. Preferably, the first magnetic layer 221 and the third magnetic layer 231 may include a CoFe-based magnetic layer having a bcc 001) structure.

The composite spacer layer 223 and the second magnetic layer 222 of the multilayer structure [Pt / Co] _N may be formed on the bottom of the first magnetic layer 221 as described with reference to FIG. 2B. When the first magnetic layer 221 is a CoFe magnetic layer having a (001) bcc structure, the first composite spacer layer 223 has a multilayer structure of Pt / Co (Co) with the tantalum layer 223a adjacent to the first magnetic layer 221, ] _N of the second magnetic layer 222 adjacent to the second magnetic layer 222. [

Similarly, when the third magnetic layer is a CoFe-based magnetic layer having a (001) bcc structure, the third composite spacer layer 233 is composed of a tantalum layer 233a adjacent to the third magnetic layer 231 and a multilayer structure [Co / Pt] _And a ruthenium layer 233b adjacent to the fourth magnetic layer 232 of _N. [

The first magnetic layer 221 and the second magnetic layer 222 may implement a magnetically fixed layer including a synthetic ferrimagnetic layer by antiparallel IEC (AP-IEC). In addition, the third magnetic layer 231 and the fourth magnetic layer 232 may be embodied as a magnetic free layer including a synthetic ferrimagnetic layer by an antiparallel IEC (AP-IEC).

2A to 2D, a magnetically fixed layer is formed on the first surface 210a of the tunnel barrier layer 210 and a magnetic free layer is formed on the second surface 210b. However, on the first surface 210a, And the above-described magnetically fixed layer is formed on the second surface 210b are also included in the scope of the present invention.

In some embodiments, a seed layer may be formed for uniform growth of the magnetic layers before forming the magnetic tunneling junctions 200A-200D on the substrate (not shown). In another embodiment, a protective layer may be further formed on the magnetic tunneling junctions 200A - 200D. In another embodiment, a buffer layer may be further formed between the magnetic layers, which will be described later. The seed layer, the buffer layer and the protective layers may include gold (Au), copper (Cu), palladium (Pd), platinum (Pt), tantalum (Ta), ruthenium The invention is not limited thereto. If tantalum and ruthenium are used as an auxiliary layer such as a seed layer, a buffer layer or a protective layer, a combination thereof can be used to provide a composite spacer layer, There is an advantageous advantage in the fabrication process that can form a composite spacer layer according to embodiments of the invention.

According to the embodiment of the present invention, by using the composite spacer layer 223 having a laminated structure of the tantalum layer 223a and the ruthenium layer 223b, a magnetic layer having a body-center cubic structure with high vertical anisotropy, for example, a CoFe- Even when the post-heat-off temperature is increased through complete structural debonding between the magnetic layer 221 and the multilayer magnetic layer including at least one unit laminate structure including a nonmagnetic metal layer having a perpendicular anisotropy excellent in thermal stability and a cobalt-containing magnetic layer, And a strong perpendicular magnetic anisotropy are ensured, reliable data recording is possible, and a multilayer magnetic thin film stack having high data retention characteristics can be provided. According to the embodiment of the present invention, the first magnetic layer 221 having the body-centered cubic crystal growth surface and the second magnetic layer 222 having the most-fine crystal growth surface are structurally decoupled, Magnetic layers 221 and 222 can be magnetically coupled with each other, and the characteristics such as the magnetic susceptibility of the magnetic structure can be controlled through the thickness control of the multi-layer magnetic layer to form a synthetic ferrimagnetic layer, A device can be provided.

Experimental Example

In order to confirm the effect of structural decoupling and / or magnetic coupling of the tantalum (Ta) layer and the ruthenium (Ru) layer-based composite spacer layer according to the embodiment of the present invention, a wet oxide film A multilayer magnetic thin film stack 2000 including the composite spacer layer 223 was formed on the formed silicon substrate to evaluate various characteristics.

Ta (thickness 5 nm: 21) / Pt (thickness 10 nm: 22) / Ru (thickness 30 nm: 23) serving as the buffer / seed layer 20 were sequentially formed on the wet oxide film 10 of the silicon substrate , And Pt (thickness 0.2 nm; 223a) / Co (thickness 0.4 nm; 223b) ₆ was formed as a second magnetic layer 222 for strengthening PMA. Thereafter, a tantalum layer 223a having a ruthenium layer 223b / thickness t _Ta having a thickness t _Ru as a composite spacer layer 223 is formed on the resultant structure, and a CoFeB magnetic layer (Thickness: 1 nm; thickness: 1 nm; 221) / MgO tunneling barrier layer (thickness: 1 nm; 210) Stack 2000 was formed. Subscript 6 of the second magnetic layer 222 means that the unit laminate structure of Pt / Co is laminated six times. 3B shows a multilayer magnetic thin film stack 2000R according to a comparative example in which a Ru layer 223 'is inserted instead of a composite spacer layer as a comparative example.

The multilayer magnetic thin film stacks 2000 and 2000R shown in FIGS. 3A and 3B are fabricated at a temperature of 10 ^-8 Torr to 10 ^-7 Torr using an ultrahigh vacuum magnetron sputtering system having one or more chambers. However, the present invention is not limited thereto. During manufacture of the stacks 2000, 2000R, the inter-chamber delivery of the manufacturing intermediate results was achieved by the robotic system with a constant pressure maintained. Since the post-heat treatment is also performed by a high-temperature process at the subsequent stage such as a wiring process for memory fabrication, the post-heat treatment is simulated, and the multilayer magnetic thin film stacks 2000 and 2000R Heat treatment was performed for about 1 hour in a temperature range of 375 캜 and a vacuum atmosphere of 1 x 10 ^-6 Torr.

The CoFeB magnetic layer as the first magnetic layer 222 was deposited using an alloy target having a composition of Co ₂₀ Fe ₆₀ B ₂₀ (the subscript is atomic%). The MgO tunneling barrier layer 210 was deposited at 1 × 10 ^-3 Torr (argon atmosphere) and the other layers were deposited at 2 × 10 ^-3 Torr (argon atmosphere). The above-described sputtering method is illustrative, and the present invention is not limited thereto. For example, these stacks may be formed by other physical vapor deposition such as electron beam evaporation, chemical vapor deposition using suitable precursors, or atomic layer deposition.

Magnetic moment-applied magnetic field ( m - H ) loops are generated by using a vibrating sample magnetometer to _{measure the} magnetic field strength of each multilayer under the out-of-plane, H _⊥ and in-plane, H _∥ magnetic fields. And magnetic properties of the magnetic thin film stacks.

Figures 4a to 4c are out-of-plane of the multi-layer magnetic thin film stack 2000 according to an embodiment of the present invention (H _⊥, ○) plane (H _∥, □) m -, and H loop graph, Figure 4d through 4f in the comparative example Lt; RTI ID = 0.0 > (2000R) < / RTI > In the composite spacer, the thickness ( t _Ru ) of the ruthenium layer is about 0.8 nm and the thickness ( t _Ta ) of the tantalum layer is about 0.4 nm. In a comparative example, the thickness (t _Ru ) of the ruthenium layer is about 0.8 nm. Figs. 4A and 4D are loop characteristics in a vapor-deposited state. Fig. 4B and Fig. 4E show the above loop characteristics annealed at 300 DEG C, and Fig. 4C and Fig. 4F show loop characteristics after annealing at 375 DEG C. The solid lines in Figs. 4B and 4E are the in-plane loops calculated from the total energy equation and the K _CoFeB value, which is the effective magnetic anisotropic energy density ( K ) of the CoFeB magnetic layer, which is the only fitting parameter from the total energy equation, .

According to an embodiment of the present invention, no PMA is observed in the deposition state (see FIG. 4A). However, it can be confirmed that PMA is formed at 300 ° C (see FIG. 4b) and 350 ° C. This indicates that crystallization of the CoFeB magnetic layer in the bcc (001) direction occurred by the composite spacer. Referring to FIG. 4B, the reverse of the CoFeB magnetic layer 221 constituting the minor loop appears suddenly, followed by the intermediate plateau, and the [Pt / Co] ₆ multilayer magnetic layer 222). ≪ / RTI > In the intermediate flat region, the CoFeB magnetic layer 221 and the [Pt / Co] ₆ multi-layered magnetic layer 222 are in an antiparallel state. More specifically, the CoFeB magnetic layer 221 has a magnetic moment magnetized antiparallel to the applied magnetic field H , while the [Pt / Co] ₆ multilayer magnetic layer 222 has a magnetic moment And has a magnetic moment parallel to the direction of the magnetic field H. The intermediate flat region is a region in which the CoFeB magnetic layer 221 and the [Pt / Co] ₆ multi-layered magnetic layer 222 according to the embodiment of the present invention are disposed in the anti-parallel interlayer exchange coupling, AP-IEC), it can be seen that a synthetic ferrimagnet suitable for ultra-high integration STT-MRAM devices can be provided.

However, in the case of the multilayer magnetic thin film stack 2000R according to the comparative example, even when the magnetic field H is decreased from the saturation value (see Fig. 4D) or after the heat treatment (see Figs. 4E and 4F) m is continuously decreased from the saturation magnetic moment value, and it can be seen that no PMA is formed in the CoFeB magnetic layer 221 from this.

In one embodiment, when a PMA is formed in the CoFeB magnetic layer 221, an exchange field ( H _ex ) is formed between the CoFeB magnetic layer 221 and the [Pt / Co] ₆ multilayer magnetic layer 222, can be determined directly from the span. If no PMA is formed in the CoFeB magnetic layer 221, H _ex can be determined as an H value when the m value is about halfway between the flat region and the saturation region in Figs. 4E and 4F. The interlayer exchange coupling energy density ( J _ex ) can be obtained from the following equation (1). Comparing the loops of FIGS. 4A-4F, it can be seen that H _ex is greater for the comparative example.

[Formula 1]

_Ex J = - m × H _{ex CoFeB} / A, where m is the magnetic moment of the _CoFeB CoFeB magnetic layer, A is laterally of the measurement sample.

4A to 4F, the saturation magnetic moment ( m _s ) is smaller in the magnetic thin film stack 2000 R of the comparative example than the multilayer magnetic thin film stack 2000 of the present invention. This is presumably due to the difference in the dead zone or the magnetic dead layer (MDL). The MDL of the comparative example appears at the interface between the Ru layer 223 'and the CoFeB magnetic layer 221 and may be larger at the interface between the Ta layer 223a and the CoFeB magnetic layer 221 of the present invention.

The saturation magnetization value m _s is also affected by the heat treatment temperature. Multi-layer magnetic thin film stack (2000R) according to the comparative example is, and the m _s value is 273 μemu in the as-deposited state, when the annealing temperature was increased from 300 ℃ to 375 ℃ and the m _s value is increased from 303 μemu to 311 μemu. In the multilayer magnetic thin film stack 2000 according to the embodiment, the saturation magnetic moment value ( m _s ) after heat treatment at 300 ° C is increased from 355 μemu to 363 μemu, and at the maximum heat treatment temperature of 375 ° C, it is 336 μemu. In any case, it can be seen that the multilayer magnetic thin film stack 2000 according to the embodiment of the present invention has a higher saturation magnetic moment value than the multilayer magnetic thin film stack 2000R according to the comparative example.

5A and 5B are graphs showing magnetization values m _s and m _r of the multilayer magnetic thin film stack 2000 including the composite spacer 223 according to the embodiment of the present invention, The effective perpendicular magnetic anisotropy energy density K _{CoFeB of} one magnetic layer, cobalt-iron-boron (CoFeB) according to an embodiment, and the interlayer exchange coupling energy density J _ex between the first magnetic layer and the second magnetic layer. The measured samples were heat treated at 300 ℃, the composite thickness of the spacer layer 223 is a ruthenium layer (223b) in the 0.3 nm to 0.9 and 0.8 nm is selected from the nm range, is 0.2 nm to 0.6 the thickness of the tantalum layer (t _Ta) lt; RTI ID = 0.0 > nm, < / RTI >

Referring to FIG. 5A, -? - represents a magnetization value ( m _s ), -? - represents a residual magnetization value ( m _r ), and? - represents a magnetization value ( m _CoFeB ) of the CoFeB magnetic layer 221. As the thickness t _Ta of the tantalum layer 223a increases, the value of m _s initially increases, and the thickness of the tantalum layer 223a reaches saturation as quickly as 0.2 nm. This means that the m _s value of the composite spacer 223 according to the present invention is higher than that of the ruthenium layer 223 'according to the comparative example, and that the multilayer magnetic thin film stack 2000 R according to the comparative example has a multi- It is presumed that a larger magnetic dead layer (MDL) is formed compared to the magnetic thin film stack 2000. Similar behavior is observed in the change of m _CoFeB value. The value of m _r for the change of the thickness t _Ta of the tantalum layer 223a has a behavior almost opposite to the m _s value and the m _CoFeB value, which is the difference between the two magnetic layers 221, 222) are in an equilibrium state.

Referring to FIG. 5B, as the thickness t _Ta of the tantalum layer 223a increases, the K _CoFeB value of the two magnetic parameters K _CoFeB and J _ex increases, but the absolute value of J _ex decreases. The behavior observed in the K _CoFeB value is due to the role of the tantalum layer 223a that absorbs boron (B) diffused from the CoFeB magnetic layer 221 during the heat treatment. It is difficult to determine the optimum value of the thickness t _Ta of the tantalum layer 223a because of the inverse proportion of the two magnetic parameters. However, since the interlayer exchange coupling is reduced to less than 1.3 x 10 ^-2 erg / cm ² when the thickness t _Ta of the tantalum layer 223a exceeds 0.6 nm, which has the maximum value, the thickness of the tantalum layer 223a t _Ta ) may be in the range of 0.2 nm to 0.4 nm.

Figure 6 is out-of-plane of the multi-layer magnetic thin film stack (2000) comprising a composite spacer 223 according to an embodiment of the invention × (H _⊥, ○) and the plane (H _∥, □) m - are H loop graph. The composite spacer 223 is formed such that the thickness t _Ta of the tantalum layer 223a is about 0.4 nm selected in the range of 0.2 nm to 0.6 nm and the thickness t _Ru of the ruthenium layer 223b is in the range of 0.2 nm to (A), (b), and (b), which are 0.3 nm and 0.5 nm and 1.0 nm and 1.2 nm selected in the range of 1 nm to 2 nm, respectively, and the measurement results of the magnetic properties with the change in the thickness t _Ru of the ruthenium layer 223b, (c) and (d). Figs. 7A and 7B are enlarged views of the minor loop portion of the out-of-plane loop measured in regions b and c of Fig. 6, respectively. All measured samples of Figure 6 and Figures 7a and 7b were heat treated at 350 占 폚.

When the thickness ( t _Ru ) of the ruthenium layer 223b is about 0.3 nm (region (a)), the characteristics relating to interlayer exchange coupling are weak. This is because the parallel loop due to the reverse of the CoFeB magnetic layer 221 is separated from the minor loop, and the parallel IEC characteristic is strong. Referring to region (b) and Figure 7a in Fig. 6, in the thickness (t _Ru) is 0.5 nm of the ruthenium layer (223b), appears a clear anti-parallel inter-layer bond (AP-IEC) characteristics, which in the magnetic field H 0 This is because the reversal of the CoFeB magnetic layer 221 occurred before reaching. Conversely, referring to regions (c) and (b) of FIG. 6, even when the thickness ( t _Ru ) of the ruthenium layer 223b is 1.0 nm, parallel interlayer bonding occurs.

8A and 8B show the interlayer exchange coupling energy ( -J _ex or -j _ex ) according to the thickness of the ruthenium layer of the multi-layer magnetic thin film stack according to the embodiment of the present invention including the composite spacer. Where j _ex is a normalized value with a maximum J _ex .

FIG. 8A shows the measurement results after the heat treatment at 300 ° C. In FIG. 8A, -? - is the measurement result of the composite spacer according to the embodiment of the present invention, and? Phys. Lett. 101 is the result obtained from JH Jung, SH Lim, and SR Lee, "Interlayer exchange coupling between [Pd / Co] multilayers and CoFeB / MgO layers with perpendicular magnetic anisotropy" Rev. B 44, 7131 SSP Parkin and D. Mauri, author of the article "Spin engineering: Direct determination of the Ruderman-Kittel-Kasuya-Yosida far-field range function in ruthenium". For comparison of these results, the value of - J _ex is the normalized value. FIG. 8B shows the result of heat treatment at 300 ° C. (- □ -), 350 ° C. (- ∇ -) and 375 ° C. (- ◇ -). In these graphs, in the case from the hysteresis loop is not possible to determine the value of J _ex, it expressed arbitrarily set to 0, and X marks. The thickness ( t _Ta ) of the tantalum layer of the composite spacer layer is 0.4 nm.

Referring to FIGS. 7A and 7B, although the thickness of the ruthenium layer 223b is relatively narrow, as the thickness of the ruthenium layer 223b increases, the common tendency of the intensity of the interlayer exchange coupling (IEC) . In addition, an important feature of the composite spacer 223 is present and are almost independent of, this bonding interlayer edification of dependence tantalum layer (223a) having a thickness (t _Ru) of ruthenium layer (223b) on the interlayer exchange coupling the tantalum layer ( 223a. ≪ / RTI > However, according to the embodiment of the present invention, the minimum value of the thickness of the ruthenium layer 223b exhibiting semi-parallel interlayer coupling is 0.4 nm, which serves to suppress the formation of pinholes that lead to the interlaminar bond. As a result, the antiparallel interlayer coupling can also be observed in the composite spacer layer 223 having a ruthenium layer 223b having a thickness as thin as 0.4 nm.

Referring to FIG. 8B, it can be seen that the tantalum layer 223a improves post-heat treatment characteristics. The antiparallel interlayer coupling occurs when the thickness ( t _Ru ) of the ruthenium layer 223b is within the range of 0.4 nm to 0.9 nm. Outside this range in the range of 0.2 nm to 1.2 nm, parallel interlayer bonding occurs. Further, it was confirmed that the strength of the interlayer bond at the thicknesses of 0.8 nm and 0.9 nm of the ruthenium layer 223b was not substantially changed at the heat treatment temperature and the post heat treatment stability was at least 375 ° C. If the thickness of the ruthenium layer (223b) (t _Ru) is a 0.6 nm, the maximum value of the stability after the heat treatment is reduced to 350 ℃, the strength of the interlayer exchange coupling in this case is ^{1.0 × 10 -2 erg / cm 2} . Similar behavior is observed when the thickness of the ruthenium layer ( t _Ru ) is 0.4 nm, and the thermal stability at this thickness is slightly reduced to 300 占 폚. The strength of the maximum interlayer exchange coupling of the composite spacer layer 223 according to the embodiment of the present invention is such that the thickness of the ruthenium layer is from 7.9 × 10 ^-2 erg / cm ² at 0.8 nm, which is 3.4 × 10 < ^-1 > erg / cm < ² >

In the range of 0.2 nm to 0.3 nm in which the thickness ( t _Ru ) of the ruthenium layer 223b is small, the exchange between the parallel layers is observed after the heat treatment at 300 占 폚, but the antiferromagnetic interlayer bonding is not observed. The interlayer exchange coupling is also observed in the thickness ( t _Ru ) of the small ruthenium layer 223b in this manner, presumably because the pinholes are suppressed by the tantalum layer 223a. However, when the heat treatment temperature is increased, the pinhole restraining force of the tantalum layer 223a is lost and the interlayer exchange coupling is extinguished.

Even at 1.0 nm and 1.2 nm in which the thickness ( t _Ru ) of the ruthenium layer 223b is large, parallel interlayer exchange coupling appears. When the thickness of the ruthenium layer ( t _Ru ) is 1.0 nm, the strength of the interlayer exchange coupling is weak after the heat treatment at 300 ° C, but there is an advantage that the strength increases when the heat treatment temperature is increased. When the thickness ( t _Ru ) of the ruthenium layer 223b is 1.2 nm, a larger parallel interlayer exchange coupling appears. However, since the parallel-to-parallel exchange coupling is so strong that the minor loop can not be separated from the major loop, the strength of the interlayer exchange coupling can not be determined at the heat treatment temperature of 350 占 폚. This is reflected in the out-of-plane history loop of the area (d) in Fig. 6 and the notation of x value at 375 캜 in Fig.

According to the embodiment of the present invention, the K _CoFeB value increases while the tantalum layer 223a absorbs boron from the adjacent CoFe magnetic layer 221 during the heat treatment of the magnetic tunneling junctions 200A - 200D, and the _post- The advantage of magnetic tunneling junctions (200A - 200D) is maintained even when the temperature increases up to 375 ℃.

The various magnetic tunneling junctions disclosed with reference to the figures attached herewith may be implemented as a single memory device or may be implemented in other wafer devices such as other heterogeneous devices such as a logic processor, And may be implemented in the form of a system on chip (SOC). Further, the wafer chip on which the memory element is formed and another wafer chip on which the heterogeneous device is formed are bonded using an adhesive layer, a soldering or a wafer bonding technique, and are implemented in a single chip form through a wiring technique such as a through silicon via . In addition, the resistance change characteristics of the magnetic tunneling junction may be utilized as fuses or anti-fuses in other devices such as logic processors.

In addition, the memory devices according to the above-described embodiments can be various types of semiconductor packages. For example, the nonvolatile memory devices according to embodiments of the present invention may be implemented in a package on package (PoP), ball grid arrays (BGAs), chip scale packages (CSPs), plastic leaded chip carriers (PLCC) Linear Package (PDIP), Die in Waffle Pack, Die in Wafer FoSM, Chip On Board (COB), Ceramic Dual In-Line Package (CERDIP), Plastic Metric Quad Flat Pack (MQFP) (SOIC), Shrink Small Outline Package (SSOP), Thin Small Outline (TSOP), Thin Quad Flatpack (TQFP), System In Package (SIP), Multi Chip Package (MCP), Wafer-level Fabricated Package Wafer-Level Processed Stack Package (WSP) or the like. The package in which the memory elements according to the embodiments of the present invention are mounted may further include a controller and / or a logic element for controlling the same.

9 is a block diagram illustrating an electronic system 4000 including a non-volatile memory device in accordance with one embodiment of the present invention.

9, an electronic system 4000 according to an embodiment of the present invention includes a controller 4010, an input / output device (I / O) 4020, a storage device 4030, an interface 4040, bus 4050). The controller 4010, the input / output device 4020, the storage device 4030 and / or the interface 4040 may be coupled to each other via the bus 4050. [ Bus 4050 may be a single or multiple bus.

The controller 4010 may include at least one of a microprocessor, a digital signal process, a microcontroller, and logic elements capable of performing similar functions. The input / output device 4020 may include a keypad, a keyboard, or a display device. The storage device 4030 may store data and / or instructions, and the storage device 4030 may include a memory cell including a magnetic tunneling junction or a multi-layer magnetic thin film stack according to various embodiments disclosed herein .

In some embodiments, the memory device 4030 may have a hybrid structure that further includes other types of semiconductor memory devices (e.g., a DRAM device and / or an Slam device). The interface 4040 may perform the function of transmitting data to or receiving data from the communication network. Interface 4040 may be in wired or wireless form. To this end, interface 4040 may comprise an antenna or a wired or wireless transceiver. Although not shown, the electronic system 4000 is an operation memory for improving the operation of the controller 4010, and may further include a high-speed DRAM and / or an SRAM.

The electronic system 4000 may be a personal digital assistant (PDA) portable computer, a tablet PC, a wireless phone, a mobile phone, a digital music player a music player, a memory card, a solid state storage device (SSD), a computer, an input device such as a display, a digitizer and a mouse, or any electronic device capable of transmitting and / have.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be clear to those who have knowledge.

Claims (20)

A magnetic tunneling junction comprising a tunneling barrier layer, a self-pinning layer on a first side of the tunneling barrier layer, and a magnetic free layer on a second side opposite the first side of the tunneling barrier layer, ,
Wherein at least one of the magnetically fixed layer and the self-
A CoFe-based first magnetic layer having a body-centered cubic structure adjacent to the tunneling barrier layer and containing cobalt (Co) and iron (Fe);
A second magnetic layer interlayer-magnetically exchange-coupled with the CoFe-based first magnetic layer; And
(Ta) layer adjacent to the first magnetic layer of CoFe and a ruthenium (Ru) layer adjacent to the second magnetic layer disposed between the first magnetic layer of the CoFe system and the second magnetic layer, Lt; RTI ID = 0.0 > 1 < / RTI > The method according to claim 1,
The tunneling barrier layer may comprise one or more of Al ₂ O ₃ , MgO, TiO ₂ , AlN, RuO, SrO, SiN, CaO _x , HfO ₂ , Ta ₂ O ₅ , ZrO ₂ , SiC, SiO ₂ , SiO _x N _y , A multilayer magnetic thin film stack comprising two or more laminated structures. The method according to claim 1,
Wherein the CoFe-based first magnetic layer comprises cobalt-iron (CoFe), cobalt-iron-boron (CoFeB), or a laminated structure of two or more thereof. The method according to claim 1,
Wherein the second magnetic layer includes a multilayer structure in which a non-magnetic metal layer and a cobalt-containing magnetic layer are alternately stacked at least once. 5. The method of claim 4,
The nonmagnetic metal layer may be at least one selected from the group consisting of Pt, Rh, Hf, Pd, Ta, Os, Ge, Ir, , And silver (Ag), or an alloy thereof. 5. The method of claim 4,
Wherein the cobalt-containing magnetic layer comprises a pure cobalt layer, a CoZr alloy layer, a CoFe alloy layer, a CoFeB alloy layer, or a laminated structure thereof. The method according to claim 1,
Wherein the CoFe-based first magnetic layer and the second magnetic layer are exchange-coupled between antiparallel layers. The method according to claim 1,
Wherein the tantalum layer of the first composite spacer layer has a thickness of 0.2 nm to 0.6 nm and the ruthenium layer has a thickness of 0.2 nm to 1.2 nm. 9. The method of claim 8,
Wherein the thickness of the ruthenium layer is in the range of 0.6 to 0.9 nm. The method according to claim 1,
And the other of the magnetically fixed layer and the self-
A CoFe-based third magnetic layer having a body-centered cubic structure adjacent to the other surface of the tunneling barrier layer in contact with the CoFe-based first magnetic layer and containing cobalt (Co) and iron (Fe);
A fourth magnetic layer interlayer-magnetically exchange-coupled with the CoFe-based third magnetic layer; And
(Ta) layer adjacent to the CoFe-based third magnetic layer and a ruthenium (Ru) layer adjacent to the fourth magnetic layer, which are disposed between the CoFe-based third magnetic layer and the fourth magnetic layer, 2 composite spacer layer. A first magnetic layer having a growth plane of (001) orientation of a body-centered cubic structure;
A second magnetic layer having a dense crystal growth surface; And
And a composite spacer layer of a tantalum layer on the first magnetic layer side and a ruthenium layer on the second magnetic layer side inserted between the first magnetic layer and the second magnetic layer. 12. The method of claim 11,
Wherein the first magnetic layer and the second magnetic layer exchange coupling between antiparallel layers. The method according to claim 1,
Wherein the tantalum layer of the composite spacer layer has a thickness of 0.2 nm to 0.6 nm and the ruthenium layer has a thickness of 0.2 nm to 1.2 nm. 14. The method of claim 13,
Wherein the thickness of the ruthenium layer is in the range of 0.6 to 0.9 nm. 12. The method of claim 11,
Further comprising a template layer for crystallization on the growth surface of the (001) orientation by heat treatment of the first magnetic layer on a surface opposite to the surface of the first magnetic layer in contact with the composite spacer layer. 16. The method of claim 15,
Wherein the template layer comprises MgO (001). 12. The method of claim 11,
Wherein the multi-layer magnetic thin film stack has perpendicular anisotropy. 12. The method of claim 11,
Wherein the first magnetic layer comprises cobalt-iron (CoFe), cobalt-iron-boron (CoFeB), or a laminated structure of two or more of them. 12. The method of claim 11,
Wherein the second magnetic layer includes a multilayer structure in which a platinum (Pt) layer and a cobalt (Co) magnetic layer are alternately stacked at least once. A non-volatile memory device comprising the multilayer magnetic thin film stack according to any one of claims 1 to 11.

Images