Claims:1. A process (10) for fabricating a magnetic tunnel junction storage element comprising:
depositing a first multiferroic ferromagnetic layer on a substrate; (20)
fabricating a barrier layer on top of the first multiferroic ferromagnetic layer; and (30)
depositing a second multiferroic ferromagnetic layer on barrier layer, (40)
wherein fabricating the barrier layer comprises sandwiching the barrier layer between the first multiferroic ferromagnetic layer and the second multiferroic ferromagnetic layer,
wherein, the barrier layer and the second multiferroic ferromagnetic layer are fabricated at a pre-defined location, and comprising a pre-defined dimensions to for obtaining the magnetic tunnel junction storage element,
wherein, an obtained magnetic tunnel junction storage element is operated by one of a magnetic field, an electric field or a combination thereof for switching the magnetic tunnel junction storage element.
2. The process (10) as claimed in claim 1, wherein depositing the first multiferroic ferromagnetic layer on the substrate comprises depositing the first multiferroic ferromagnetic layer on one of silicon (Si), a silicon dioxide (SiO2), a platinum (Pt), or a combination thereof.
3. The process (10) as claimed in claim 1, wherein fabricating the barrier layer comprises fabricating the barrier layer composed of silicon (Si).
4. The process (10) as claimed in claim 1, comprising:
patterning at least one of the first multiferroic ferromagnetic layer, the second multiferroic ferromagnetic layer, the barrier layer, or a combination thereof;
fabricating a first electrode on the first multiferroic ferromagnetic layer; and
fabricating a second electrode on the second multiferroic ferromagnetic layer.
5. A magnetic tunnel junction storage element (40) comprising:
a substrate (50), wherein the substrate (50) is composed of on one of silicon (Si), a silicon dioxide (SiO2), a platinum (Pt), or a combination thereof;
a first multiferroic ferromagnetic layer (60) deposited on the substrate (50);
a barrier layer (70) deposited on the first multiferroic ferromagnetic layer (60); and
a second multiferroic ferromagnetic layer (80) deposited on the barrier layer (70).
6. The magnetic tunnel junction storage element (40) as claimed in claim 5, wherein the barrier layer (70) is composed of silicon (Si).
7. The magnetic tunnel junction storage element (40) as claimed in claim 5, comprising:
a first electrode (90) fabricated on the first multiferroic ferromagnetic layer (60); and
a second electrode (100) fabricated on the second multiferroic ferromagnetic layer (80).
8. A non-volatile memory storage device comprising a plurality of magnetic tunnel junction storage elements, wherein each of the plurality of magnetic tunnel junction storage elements comprises:
a substrate, wherein the substrate is composed of on one of silicon (Si), a silicon dioxide (SiO2), a platinum (Pt), or a combination thereof;
a first multiferroic ferromagnetic layer deposited on the substrate;
a barrier layer deposited on the first multiferroic ferromagnetic layer; and
a second multiferroic ferromagnetic layer deposited on the barrier layer.
9. The non-volatile memory storage device as claimed in claim 8, wherein the barrier layer is composed of silicon (Si).
10. The non-volatile memory storage device as claimed in claim 8, wherein a thickness of the first multiferroic ferromagnetic layer is about 10 nano meter (nm), wherein a thickness of the second multiferroic ferromagnetic layer is about 5 nano meter (nm).

Dated this 07th day of September 2020

Signature

Vidya Bhaskar Singh Nandiyal
Patent Agent (IN/PA-2912)
Agent for the Applicant
, Description:FIELD OF INVENTION
[0001] Embodiments of a present invention relate to magnetic tunnel junction device, and more particularly to, a magnetic tunnel junction storage element and a process of fabrication.
BACKGROUND
[0002] Magnetic tunnel junction (MTJ) devices which is majorly used in storage applications. In a conventional approach, the MTJ consist of ferromagnetic layers sandwiched with barrier. Such a conventional application is mostly applied in tunnel magnetoresistance (TMR) devices upon applying logic ‘0’ logic ‘1’ states. However, such a conventional approach is slower as huge amount of time is consumed in analysing the change of the logics, thereby making such a conventional approach less reliable.
[0003] In comparison to the conventional approach, the newer approach gave raise to a field of spintronics. The spintronics utilises movement or spin of electronics to calculate the logic states. In the newer approach, the MJT devices are comprised of two layers of ferromagnetic material separated by a thin insulating tunnel barrier layer. Existing solid-state non-volatile memory devices such as MRAM, flash memory, spin RAM have limited size (in comparison with disc drives) and have practical performance; such limitations makes the newer approach long-term non-volatility or a need to compromise on memory size. Also, devices in the newer approach will work only when magnetic field is being applied. In addition, the MJT devices of the newer approach have no precise spin polarization that leads to spin scattering, resulting in low MR limiting the practical applications of the MJT devices. Furthermore, integration of such MJT devices to an existing electronic equipment is a lethargic process.
[0004] Hence there is a need for an improved magnetic tunnel junction storage element and a process of fabrication to address the aforementioned issues.

BRIEF DESCRIPTION
[0005] In accordance with one embodiment of the disclosure, a process for fabricating a magnetic tunnel junction storage element is disclosed. The process includes depositing a first multiferroic ferromagnetic layer on a substrate. The process also includes fabricating a barrier layer on top of the first multiferroic ferromagnetic layer. The process also includes depositing a second multiferroic ferromagnetic layer on barrier layer. Fabricating the barrier layer comprises sandwiching the barrier layer between the first multiferroic ferromagnetic layer and the second multiferroic ferromagnetic layer. The barrier layer and the second multiferroic ferromagnetic layer are fabricated at a pre-defined location, and comprising a pre-defined dimensions to for obtaining the magnetic tunnel junction storage element. A magnetic tunnel junction storage element is operated by one of a magnetic field, an electric field or a combination thereof for switching the magnetic tunnel junction storage element.
[0006] In accordance with another embodiment, a magnetic tunnel junction (MTJ) storage element is disclosed. The MTJ element includes a substrate. The substrate is composed of on one of silicon (Si), a silicon dioxide (SiO2), a platinum (Pt), or a combination thereof. The MTJ element also includes a first multiferroic ferromagnetic layer deposited on the substrate. The MTJ element also includes a barrier layer deposited on the first multiferroic ferromagnetic layer. The MTJ element also includes a second multiferroic ferromagnetic layer deposited on the barrier layer.
[0007] To further clarify the advantages and features of the present disclosure, a more particular description of the disclosure will follow by reference to specific embodiments thereof, which are illustrated in the appended figures. It is to be appreciated that these figures depict only typical embodiments of the disclosure and are therefore not to be considered limiting in scope. The disclosure will be described and explained with additional specificity and detail with the appended figures.

BRIEF DESCRIPTION OF THE DRAWINGS
The disclosure will be described and explained with additional specificity and detail with the accompanying figures in which:
[0008] FIG. 1 is a flow chart representing steps involved in a process for fabricating a magnetic tunnel junction storage element in accordance with an embodiment of the present disclosure;
[0009] FIG. 2 is a schematic representation of a magnetic tunnel junction (MTJ) storage element in accordance with an embodiment of the present disclosure;
[00010] FIG. 3 is a graph representation of a positive and negative bias for voltage of refers to electrons tunneling from a first multiferroic ferromagnetic layer and a second multiferroic ferromagnetic layer the MTJ storage element of FIG. 2 in accordance with an embodiment of the present disclosure;
[00011] FIG. 4 is a graph representation of an X-ray diffraction (XRD) pattern of the first multiferroic ferromagnetic layer deposited on a substrate of FIG. 2 in accordance with an embodiment of the present disclosure;
[00012] FIG. 5 is a graph representing magnetic properties of the free and pinned layers studied using the Quantum Design Physical Properties Measurement System (PPMS) of FIG. 2 in accordance with an embodiment of the present disclosure;
[00013] FIG. 6 is a graph representing tunneling magnetoresistance carried out on MTJ of FIG. 2 at different temperatures in accordance with an embodiment of the present disclosure; and
[00014] FIG. 7 is a graph representing a variation of TMR with the temperature of the invention of FIG. 2 at different temperatures in accordance with an embodiment of the present disclosure.
[00015] Further, those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and may not have necessarily been drawn to scale. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the figures with details that will be readily apparent to those skilled in the art having the benefit of the description herein.
DETAILED DESCRIPTION
[00016] For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Such alterations and further modifications in the illustrated system, and such further applications of the principles of the disclosure as would normally occur to those skilled in the art are to be construed as being within the scope of the present disclosure.
[00017] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Similarly, one or more devices or sub-systems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other devices, sub-systems, elements, structures, components, additional devices, additional sub-systems, additional elements, additional structures or additional components. Appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.
[00018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. The system, process, and examples provided herein are only illustrative and not intended to be limiting.
[00019] In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.
[00020] Embodiments of the present disclosure relate to a magnetic tunnel junction storage element and a process of fabrication.
[00021] Turning to FIGs. 1 and 2, FIG. 1 is a flow chart representing steps involved in a process (10) for fabricating a magnetic tunnel junction (MTJ) storage element in accordance with an embodiment of the present disclosure. FIG. 2 is a schematic representation of a magnetic tunnel junction (MTJ) storage element in accordance with an embodiment of the present disclosure. The process (10) includes depositing a first multiferroic ferromagnetic (BFNO) layer (60) on a substrate (50) in step 20. In one embodiment, depositing the first multiferroic ferromagnetic layer (60) on the substrate (50) may include depositing the first multiferroic ferromagnetic layer (60) on one of silicon (Si), a silicon dioxide (SiO2), a platinum (Pt), or a combination thereof. In one preferred embodiment, the substrate may be a Pt-Si substrate. Further, in one exemplary embodiment, the first BFNO layer (60) may be fabricated of thickness of about 10 nanometer (nm).
[00022] The process (10) also includes fabricating a barrier layer (70) on top of the first multiferroic ferromagnetic layer (60) in step 30. In one embodiment, fabricating the barrier layer (70) may include fabricating the barrier layer composed of silicon (Si). In one exemplary embodiment, the Si barrier layer may be of thickness of about 2-millimeter (mm), which may be deposited using radio frequency (RF) magnetron sputtering technique within an argon (Ar) atmosphere. In such embodiment, the temperature of Ar during the RF magnetron sputtering technique may be maintained at about 9.3 × 10–4 mbar. Furthermore, the process (10) includes depositing a second multiferroic ferromagnetic (BFNO) layer (80) on barrier layer in step 40. In one embodiment, the second BFNO layer (80) may be fabricated with the thickness of about 5 nm.
[00023] Consequently, fabricating the barrier layer (70) may include sandwiching the barrier layer (70) between the first multiferroic ferromagnetic layer (60) and the second multiferroic ferromagnetic layer (80). The barrier layer (70) and the second multiferroic ferromagnetic layer (80) are fabricated at a pre-defined location, and comprising a pre-defined dimensions to for obtaining the magnetic tunnel junction storage element (as shown in FIG. 2) (40). In one specific embodiment, the pre-defined location may be towards at one of the two ends on the substrate. The obtained magnetic tunnel junction storage element (40) is operated by one of a magnetic field, an electric field or a combination thereof for switching the magnetic tunnel junction storage element.
[00024] In one exemplary embodiment, the process (10) may further include patterning at least one of the first multiferroic ferromagnetic layer (60), the second multiferroic ferromagnetic layer (80), the barrier layer (70), or a combination thereof. In such embodiment, patterning the first BFNO layer (60), the second BFNO layer (80) may be achieved by adapting an etching technique. The process may further include fabricating a first electrode (90) on the first multiferroic ferromagnetic layer (60). In one embodiment, negative voltage may be supplied to the first multiferroic ferromagnetic layer (60) via the first electrode (90). The process (10) may further include fabricating a second electrode (100) on the second multiferroic ferromagnetic layer . In one embodiment, positive voltage may be supplied to the second multiferroic ferromagnetic layer.
[00025] FIG. 3 is a graph (110) representation of a positive and negative bias for voltage of refers to electrons tunneling from the first multiferroic ferromagnetic layer and the second multiferroic ferromagnetic layer the MTJ storage element of FIG. 2 in accordance with an embodiment of the present disclosure. FIG. 3 represents experimental results obtain on measuring current- voltage (I-V) characteristics (110) of the obtained MTJ storage element (40) during the tunneling of electrons from the first multiferroic ferromagnetic layer (60) and the second multiferroic ferromagnetic layer (80) of the MTJ storage element (40). Upon studying and analysing the I-V characteristics, all plots illustrated in the graph, the plots show the modest variations of junction resistance to temperature and possess non-linear characteristics, indicating that electron tunneling through silicon is predominant. The positive and negative bias for voltage refers to electrons tunneling from the first BFNO layer (60) to the second BFNO layer (‘80) through silicon (70) and vice versa.
[00026] FIG. 4 is a graph (120) representation of an X-ray diffraction (XRD) pattern of the first multiferroic ferromagnetic layer deposited on a substrate of FIG. 2 in accordance with an embodiment of the present disclosure. The XRD pattern (120) of the first BPNO layer (60) is taken upon growing or depositing the first BFNO layer (60) on the Pt-Si substrate (50). The plot shows the formation of pure phase of the first BFNO layer (60) without any secondary phases. The peak at about 2 Theta of 32 degrees, 45 degrees, and 61 degrees corresponds to the orientation of BFNO.
[00027] FIG. 5 is a graph (130) representing magnetic properties of the free and pinned layers studied using the Quantum Design Physical Properties Measurement System (PPMS) of FIG. 2 in accordance with an embodiment of the present disclosure. The first BFNO layer (60) and the second BFNO layer (80) were studied using the Quantum Design Physical Properties Measurement System (PPMS). Turning to FIGs. 3 and 4, the graphs (110, 120) act as an evident exhibiting hysteresis, with different coercivity. The insight into the thickness of the BFNO layer (60) and the second BFNO layer (80), which are the ferromagnetic (FM) layers is evident for adjusting the coercive, which, in turn, acts as a free and pinned layer, desirable for MTJ storage element (40). Further, with a low loop area, the second BFNO layer (80) with 5 nm thickness can be easily magnetized and demagnetized. However, a large loop area of the second BFNO layer (60) having 10 nm thickness will act as a pinned layer, as it would be analogous to the hard magnet.
[00028] FIG. 6 is a graph (140) representing tunneling magnetoresistance carried out on MTJ (40) of FIG. 2 at different temperatures in accordance with an embodiment of the present disclosure. The graph represents spin transport through silicon. When the graph as represented in FIG. 6 is further analysed, at room temperature, MR is not like the typical MR behavior, and reasons may be due to impedance mismatch with the second BFNO layer (80) and Si. For low temperature, the symmetrical butterfly-like shape of characteristic MR is observed. In one exemplary embodiment, the Magnetoresistance (MR) behavior means change of resistance by applying magnetic field from low to high by tuning or sweeping the magnetic field from low to high. Typically refers to clear change in resistance from low to high- appears similar to upper part of sine wave.
[00029] FIG. 7 is a graph (150) representing a variation of TMR with the temperature of the invention of FIG. 2 at different temperatures in accordance with an embodiment of the present disclosure. When the graph is observed, MR behavior was found to be increasing with temperature and reaches a maximum at 77 K and decreases with further increase in temperature. This phenomenon may be obtained due to scattering mechanism observed in the MJT storage element.
[00030] Furthermore, a magnetic tunnel junction (MTJ) storage element (40) is disclosed in accordance with an embodiment of the present disclosure. The MTJ storage element (40) includes a substrate (50), wherein the substrate (50) is composed of on one of silicon (Si), a silicon dioxide (SiO2), a platinum (Pt), or a combination thereof. The MTJ storage element (40) also includes a first multiferroic ferromagnetic layer (60) deposited on the substrate (50). In one exemplary embodiment, the first multiferroic ferromagnetic layer (60) may be having a thickness of about 10 mm.
[00031] Furthermore, the MTJ storage element (40) further includes the barrier layer (70) deposited on the first multiferroic ferromagnetic layer (60). In one embodiment, the barrier layer (70) may be composed of silicon (Si). In one embodiment, the barrier layer (70) may be fabricated at a pre-defined location on the first multiferroic ferromagnetic layer (60). The MTJ storage element (40) also includes the second multiferroic ferromagnetic layer (80) deposited on the barrier layer (70). In one exemplary embodiment, the second multiferroic ferromagnetic layer (80) may be having a thickness of about 5 mm.
[00032] A non-volatile memory storage device comprising a plurality of magnetic tunnel junction storage elements is further disclosed in accordance with an embodiment of the present disclosure. Each of the plurality of magnetic tunnel junction (MTJ) storage elements includes a substrate, wherein the substrate is composed of on one of silicon (Si), a silicon dioxide (SiO2), a platinum (Pt), or a combination thereof. Each of the plurality of magnetic tunnel junction (MTJ) storage elements also includes a first multiferroic ferromagnetic layer deposited on the substrate. Each of the plurality of magnetic tunnel junction (MTJ) storage elements also includes a barrier layer deposited on the first multiferroic ferromagnetic layer. In one embodiment, the barrier layer may composed of silicon (Si).
[00033] Each of the plurality of magnetic tunnel junction (MTJ) storage elements also includes a second multiferroic ferromagnetic layer deposited on the barrier layer. In one embodiment, the thickness of the first multiferroic ferromagnetic layer is about 10 nano meter (nm), wherein a thickness of the second multiferroic ferromagnetic layer is about 5 nano meter (nm). It should be noted that due to magnetoresistance effect of the MTJ storage element, they are used in the storage devices such as a magneto resistive read only memory (MRAM) devices. Magnetoresistance can be controlled by both electrically and magnetically because the device used in the present invention is the multiferroic. The logic ‘0’ and ‘1’ can be controlled as four state to eight state by controlling ferroelectric and ferromagnetic state of the multiferroic FM layers. Further, the MJT storage element’s performance utilizes TMR effect.
[00034] Various embodiments of the magnetic tunnel junction storage element and a process of fabrication enable the MJT to use multiferroic Bi2FeNiO6 layers as ferromagnetic layers in MTJ, thereby creating a magnetoresistance material, which can be switched using the spin in spintronics, thereby the state of the device is measured in terms of spins of the electrons present in the layers of the MJT device. Also, working of the MTJ device can be controlled using magnetic field, electric field or both. More specifically, logic operations of the MJT storage element can be controlled by switching electrically and magnetically.
[00035] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.
[00036] The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, order of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts need to be necessarily performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples.