阅读说明：本技术 磁隧道结的制备方法及单元结构 (Preparation method of magnetic tunnel junction and unit structure ) 是由 陈文静 殷加亮 郭宗夏 曹凯华 赵巍胜 于 2020-12-23 设计创作，主要内容包括：本发明提供了一种磁隧道结的制备方法及单元结构,所述制备方法包括：在衬底上形成底电极层；在所述底电极层上形成磁隧道结；在所述磁隧道结和所述底电极层组成的表面上形成第一介质层,并根据底电极图案对所述底电极层进行图案化；在图案化后的底电极层和第一介质层组成的表面上形成第二介质层；刻蚀所述第二介质层直至所述底电极层和所述磁隧道结分别得到底电极通孔和顶电极通孔并金属化,本发明可降低或避免刻蚀副产物再沉积带来的影响。(The invention provides a preparation method and a unit structure of a magnetic tunnel junction, wherein the preparation method comprises the following steps: forming a bottom electrode layer on a substrate; forming a magnetic tunnel junction on the bottom electrode layer; forming a first dielectric layer on the surface formed by the magnetic tunnel junction and the bottom electrode layer, and patterning the bottom electrode layer according to a bottom electrode pattern; forming a second dielectric layer on the surface formed by the patterned bottom electrode layer and the first dielectric layer; and etching the second dielectric layer until the bottom electrode layer and the magnetic tunnel junction respectively obtain a bottom electrode through hole and a top electrode through hole and are metallized.)

1. A method for manufacturing a magnetic tunnel junction, comprising:

forming a bottom electrode layer on a substrate;

forming a magnetic tunnel junction on the bottom electrode layer;

forming a first dielectric layer on the surface formed by the magnetic tunnel junction and the bottom electrode layer, and patterning the bottom electrode layer according to a bottom electrode pattern;

forming a second dielectric layer on the surface formed by the patterned bottom electrode layer and the first dielectric layer;

and etching the second dielectric layer until the bottom electrode layer and the magnetic tunnel junction respectively obtain a bottom electrode through hole and a top electrode through hole, and metalizing.

2. The method of claim 1, wherein the forming a magnetic tunnel junction on the bottom electrode layer specifically comprises:

forming a core layer on the bottom electrode layer;

forming a clad layer on the core layer;

forming a third dielectric layer on the covering layer and forming a magnetic tunnel junction pattern on the third dielectric layer;

and etching the core layer and the covering layer by taking the third dielectric layer with the magnetic tunnel junction graph as a mask to obtain the magnetic tunnel junction.

3. The method for preparing a magnetic tunnel junction according to claim 2, wherein etching the second dielectric layer until the bottom electrode layer and the magnetic tunnel junction are respectively provided with a bottom electrode through hole and a top electrode through hole and metallized specifically comprises:

etching the second dielectric layer until the bottom electrode layer and the covering layer respectively obtain a bottom electrode through hole and a top electrode through hole;

and metalizing the bottom electrode through hole and the top electrode through hole.

4. The method of claim 3, wherein the metallizing the bottom electrode via and the top electrode via specifically comprises:

forming a metal layer on the surface formed by the second dielectric layer, the bottom electrode through hole and the top electrode through hole;

and patterning the metal layer to reserve the metal layers of the bottom electrode through hole and the top electrode through hole to realize metallization of the bottom electrode through hole and the top electrode through hole.

5. The method of claim 1, further comprising, prior to forming the first dielectric layer:

and carrying out oxidation treatment on the side wall of the magnetic tunnel junction to obtain a first side wall oxide layer.

6. The method of claim 1, wherein the patterning the bottom electrode layer according to a bottom electrode pattern specifically comprises:

forming a bottom electrode pattern on the first dielectric layer;

and etching the bottom electrode layer by taking the first dielectric layer with the bottom electrode pattern as a mask so as to realize patterning of the bottom electrode layer.

7. The method of claim 1, further comprising, prior to forming the second dielectric layer:

and carrying out oxidation treatment on the patterned bottom electrode layer to obtain a second side wall oxide layer.

8. A magnetic tunnel junction cell structure, comprising:

a substrate;

a bottom electrode layer formed on the substrate;

a magnetic tunnel junction formed on the bottom electrode layer;

a first dielectric layer formed on a surface comprised of the magnetic tunnel junction and the bottom electrode layer, having a bottom electrode pattern for patterning the bottom electrode layer;

a second dielectric layer formed on the surface composed of the patterned bottom electrode layer and the first dielectric layer;

and the metalized bottom electrode through hole and the metalized top electrode through hole penetrate through the second dielectric layer, the bottom electrode layer and the magnetic tunnel junction.

9. The mtj cell structure of claim 8, further comprising a first sidewall oxide layer formed by oxidizing sidewalls of the mtj.

10. The mtj cell structure of claim 8, further comprising a second sidewall oxide layer formed by oxidizing the patterned bottom electrode layer.

Technical Field

The invention relates to the technical field of spin electronic devices, in particular to a preparation method and a unit structure of a magnetic tunnel junction.

Background

A Magnetic Tunnel Junction (MTJ) is one of core devices for Magnetic Random Access Memory (MRAM), TMR type spin sensor (Spintronics sensor), and the like. The magnetic tunnel junction is generally prepared by adopting a subtractive process, namely, a bottom electrode, a TMR film stack and a top electrode are firstly deposited on a substrate, the bottom electrode and the MTJ are patterned by utilizing photoetching and dry etching, the side wall of the MTJ is protected by adopting a dielectric layer, and finally the top electrode and the bottom electrode of the MTJ are interconnected. In the dry etching process of the MTJ, etching byproducts are redeposited on the side wall of the patterned film stack, so that the Tunneling Magnetoresistance Ratio (TMR) of the MTJ is reduced, and even the free layer and the reference layer of the MTJ are short-circuited to fail.

Disclosure of Invention

An object of the present invention is to provide a method for fabricating a magnetic tunnel junction, which reduces or avoids the influence of redeposition of etching byproducts. It is another object of the present invention to provide a magnetic tunnel junction cell structure.

In order to achieve the above object, in one aspect, the present invention discloses a method for manufacturing a magnetic tunnel junction, including:

forming a bottom electrode layer on a substrate;

forming a magnetic tunnel junction on the bottom electrode layer;

forming a first dielectric layer on the surface formed by the magnetic tunnel junction and the bottom electrode layer, and patterning the bottom electrode layer according to a bottom electrode pattern;

forming a second dielectric layer on the surface formed by the patterned bottom electrode layer and the first dielectric layer;

and etching the second dielectric layer until the bottom electrode layer and the magnetic tunnel junction respectively obtain a bottom electrode through hole and a top electrode through hole, and metalizing.

Preferably, the forming of the magnetic tunnel junction on the bottom electrode layer specifically includes:

forming a core layer on the bottom electrode layer;

forming a clad layer on the core layer;

forming a third dielectric layer on the covering layer and forming a magnetic tunnel junction pattern on the third dielectric layer;

and etching the core layer and the covering layer by taking the third dielectric layer with the magnetic tunnel junction graph as a mask to obtain the magnetic tunnel junction.

Preferably, the etching the second dielectric layer until the bottom electrode layer and the magnetic tunnel junction respectively obtain a bottom electrode through hole and a top electrode through hole, and the metallizing specifically includes:

etching the second dielectric layer until the bottom electrode layer and the covering layer respectively obtain a bottom electrode through hole and a top electrode through hole;

and metalizing the bottom electrode through hole and the top electrode through hole.

Preferably, the step of metalizing the bottom electrode through hole and the top electrode through hole specifically comprises:

forming a metal layer on the surface formed by the second dielectric layer, the bottom electrode through hole and the top electrode through hole;

and patterning the metal layer to reserve the metal layers of the bottom electrode through hole and the top electrode through hole to realize metallization of the bottom electrode through hole and the top electrode through hole.

Preferably, the method further comprises, before forming the first dielectric layer:

and carrying out oxidation treatment on the side wall of the magnetic tunnel junction to obtain a first side wall oxide layer.

Preferably, the patterning the bottom electrode layer according to the bottom electrode pattern specifically includes:

forming a bottom electrode pattern on the first dielectric layer;

and etching the bottom electrode layer by taking the first dielectric layer with the bottom electrode pattern as a mask so as to realize patterning of the bottom electrode layer.

Preferably, the method further comprises, before forming the second dielectric layer:

and carrying out oxidation treatment on the patterned bottom electrode layer to obtain a second side wall oxide layer.

The invention also discloses a magnetic tunnel junction unit structure, comprising:

a substrate;

a bottom electrode layer formed on the substrate;

a magnetic tunnel junction formed on the bottom electrode layer;

a first dielectric layer formed on a surface comprised of the magnetic tunnel junction and the bottom electrode layer, having a bottom electrode pattern for patterning the bottom electrode layer;

a second dielectric layer formed on the surface composed of the patterned bottom electrode layer and the first dielectric layer;

and the metalized bottom electrode through hole and the metalized top electrode through hole penetrate through the second dielectric layer, the bottom electrode layer and the magnetic tunnel junction.

Preferably, the method further includes oxidizing a sidewall of the magnetic tunnel junction to obtain a first sidewall oxide layer.

Preferably, the method further comprises a second sidewall oxide layer obtained by performing oxidation treatment on the patterned bottom electrode layer.

The method comprises the steps of forming a bottom electrode layer on a substrate, forming a magnetic tunnel junction on the bottom electrode layer, patterning the bottom electrode layer, and finally forming and metalizing a bottom electrode through hole and a top electrode through hole. In addition, the first dielectric layer is used as a hard mask for etching the bottom electrode layer, and compared with a metal hard mask in the prior art, the thickness of the etched metal can be reduced, and the redeposition of etching byproducts can be reduced. Therefore, the invention optimizes the preparation method of the MTJ by preparing the MTJ first and then patterning the bottom electrode layer, and reduces or avoids the influence of the redeposition of etching byproducts in the preparation of the MTJ on the performance of the MTJ.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a flow chart illustrating one embodiment of a method of fabricating a magnetic tunnel junction of the present invention;

FIG. 2 shows a flow chart of a method S200 for fabricating a magnetic tunnel junction according to an embodiment of the present invention;

FIG. 3 is a flow chart of a method S500 for fabricating a magnetic tunnel junction according to an embodiment of the present invention;

FIG. 4 is a flow chart of a method S520 for fabricating a magnetic tunnel junction according to an embodiment of the present invention;

FIG. 5 shows a flow chart of S200 of one embodiment of a method for fabricating a magnetic tunnel junction of the present invention including S250;

FIG. 6 is a flow chart of a method S300 for fabricating a magnetic tunnel junction according to an embodiment of the present invention;

FIG. 7 shows a flow chart of S300 including S330 according to a specific embodiment of the method for fabricating a magnetic tunnel junction of the present invention;

FIG. 8 is a flowchart showing a specific example of a method for manufacturing a magnetic tunnel junction according to the present invention;

fig. 9A to 9G illustrate cross-sectional views of the magnetic tunnel junction cell structure of the steps in fig. 8.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

According to an aspect of the present invention, the present embodiment discloses a method of fabricating a magnetic tunnel junction. As shown in fig. 1, in this embodiment, the method includes:

s100: a bottom electrode layer is formed on a substrate.

S200: a magnetic tunnel junction is formed on the bottom electrode layer.

S300: and forming a first dielectric layer on the surface formed by the magnetic tunnel junction and the bottom electrode layer, and patterning the bottom electrode layer according to a bottom electrode pattern.

It can be appreciated that using the first dielectric layer as a hard mask for etching the bottom electrode layer to pattern the bottom electrode layer can reduce the thickness of the etched metal compared to a metal hard mask, thereby reducing the thickness of the etched metal and reducing the redeposition of etch byproducts.

S400: and forming a second dielectric layer on the surface formed by the patterned bottom electrode layer and the first dielectric layer.

S500: and etching the second dielectric layer until the bottom electrode layer and the magnetic tunnel junction respectively obtain a bottom electrode through hole and a top electrode through hole, and metalizing.

The method comprises the steps of forming a bottom electrode layer on a substrate, forming a magnetic tunnel junction on the bottom electrode layer, patterning the bottom electrode layer, and finally forming and metalizing a bottom electrode through hole and a top electrode through hole. In addition, the first dielectric layer is used as a hard mask for etching the bottom electrode layer, and compared with a metal hard mask in the prior art, the thickness of the etched metal can be reduced, and the redeposition of etching byproducts can be reduced. Therefore, the invention optimizes the preparation method of the MTJ by preparing the MTJ first and then patterning the bottom electrode layer, and reduces or avoids the influence of the redeposition of etching byproducts in the preparation of the MTJ on the performance of the MTJ.

In a preferred embodiment, as shown in fig. 2, the forming a magnetic tunnel junction on the bottom electrode layer by S200 specifically includes:

s210: a core layer is formed on the bottom electrode layer. The core layer is a core film layer forming a high-resistance state and a low-resistance state, and mainly includes a free layer, a barrier layer, a reference layer, a pinning layer, and the like, wherein each layer may be a single layer or a combination of multiple layers of magnetic material thin film nonmagnetic materials.

S220: forming a clad layer on the core layer. Wherein the capping layer may function as a buffer, protection and etch stop layer. Preferably, the material of the capping layer may be Ru, Ta, Pt, or the like. In other embodiments, the covering layer may be made of other materials available in the art, and the present invention is not limited thereto.

S230: and forming a third dielectric layer on the covering layer, and forming a magnetic tunnel junction pattern on the third dielectric layer. Specifically, the third dielectric layer can be used as a hard mask for etching the MTJ. The magnetic tunnel junction pattern can be transferred to the third dielectric layer through the steps of deposition, exposure, cleaning and the like of photoresist, and the process is a conventional technical means in the field and is not described herein again.

S240: and etching the core layer and the covering layer by taking the third dielectric layer with the magnetic tunnel junction graph as a mask to obtain the magnetic tunnel junction.

It can be appreciated that in the preferred embodiment, by forming a third dielectric layer on the core layer and the capping layer, and using the third dielectric layer as a hard mask for etching to form the magnetic tunnel junction, the thickness of the etched metal can be reduced compared to a metal hard mask, thereby reducing the thickness of the etched metal and reducing the redeposition of etching byproducts.

The core layer mainly includes film layers such as a free layer, a barrier layer, a reference layer, and a pinning layer, which are sequentially disposed from top to bottom. In an optional implementation manner, in the process of etching the core layer and the capping layer by using the third dielectric layer as a mask to obtain the magnetic tunnel junction, the etching of the core layer may include etching of film layers such as a free layer, a barrier layer, a reference layer, and a pinning layer. In other alternative embodiments, the etching of the core layer may be completed by etching only the free layer and the barrier layer, i.e., stopping the etching when the barrier layer is etched, leaving the reference layer and the pinned layer.

In a preferred embodiment, as shown in fig. 3, the etching the second dielectric layer until the bottom electrode layer and the magnetic tunnel junction respectively obtain a bottom electrode through hole and a top electrode through hole and metallizing specifically includes:

s510: and etching the second dielectric layer until the bottom electrode layer and the covering layer respectively obtain a bottom electrode through hole and a top electrode through hole.

S520: and metalizing the bottom electrode through hole and the top electrode through hole.

It is understood that the bottom electrode via hole and the top electrode via hole are formed by etching the second dielectric layer up to the bottom electrode layer and the capping layer of the magnetic tunnel junction, and the bottom electrode via hole and the top electrode via hole are metallized, i.e. a metal layer is formed on the surface of the second dielectric layer extending to the bottom electrode layer and the capping layer. And the metalized bottom electrode through hole and the metalized top electrode through hole are electrically connected with an external circuit, so that the transmission of current signals of the bottom electrode layer and the magnetic tunnel junction is realized.

In a preferred embodiment, as shown in fig. 4, the step S520 of metalizing the bottom electrode via and the top electrode via specifically includes:

s521: forming a metal layer on the surface formed by the second dielectric layer, the bottom electrode through hole and the top electrode through hole;

s522: and patterning the metal layer to reserve the metal layers of the bottom electrode through hole and the top electrode through hole to realize metallization of the bottom electrode through hole and the top electrode through hole.

It can be understood that, in order to metalize the bottom electrode through hole and the top electrode through hole, a metal layer is required to be formed on the surface formed by the second dielectric layer, the bottom electrode through hole and the top electrode through hole, then a photoresist mask for etching the metal layer is formed by depositing and exposing photoresist on the metal layer according to an electrode pattern, the metal layer is etched by using the photoresist mask, the metal layer of the bottom electrode through hole and the top electrode through hole is reserved, the metallization of the bottom electrode through hole and the top electrode through hole is realized, and finally the photoresist mask is stripped. This process is conventional in the art and will not be described further herein. In the preferred embodiment, by finally forming the bottom electrode layer and the metalized through hole for electrically connecting the magnetic tunnel junction with the external circuit, the influence of the redeposition of etching byproducts formed by etching metal on the magnetic tunnel junction unit structure can be avoided.

It should be noted that, the bottom electrode through hole and the top electrode through hole may be formed by a single process, or may be formed by multiple processes, which is not limited in the present invention, and the technical solution including forming the bottom electrode through hole and the top electrode through hole by a single process and forming the bottom electrode through hole and the top electrode through hole by multiple processes based on the same inventive concept as the present invention is also within the protection scope of the present invention. The number of the bottom electrode through holes may be one or more, that is, one bottom electrode through hole is formed for each of different regions of the bottom electrode layer. Preferably, the depth-to-width ratio of the bottom electrode through hole and/or the top electrode through hole is 0.1-0.5. In practical applications, the aspect ratio of the bottom electrode through hole and the top electrode through hole may also be flexibly set according to practical requirements, which is not limited in the present invention.

In a preferred embodiment, as shown in fig. 5, further comprising, prior to forming the first dielectric layer:

s250: and carrying out oxidation treatment on the side wall of the magnetic tunnel junction to obtain a first side wall oxide layer.

It can be understood that after the MTJ is formed by etching, the MTJ sidewalls are oxidized to change the metal component in the etching byproducts to oxide, which can reduce or avoid the effect on the MTJ performance. Moreover, the oxidation treatment in the preferred embodiment can be performed in situ after etching, which is easy to operate and avoids the influence of exposed MTJ. The oxidation treatment may be performed using oxygen or a mixed gas containing oxygen, and for example, may be performed using a mixed gas of oxygen, argon, ozone, or the like. In other embodiments, other materials and gases that are feasible in the art may be used for the oxidation process, and the present invention is not limited thereto.

In a preferred embodiment, as shown in fig. 6, the step S300 of patterning the bottom electrode layer according to the bottom electrode pattern specifically includes:

s310: and forming a bottom electrode pattern on the first dielectric layer.

S320: and etching the bottom electrode layer by taking the first dielectric layer with the bottom electrode pattern as a mask so as to realize patterning of the bottom electrode layer.

Similarly, the bottom electrode pattern can be transferred to the first dielectric layer through the steps of depositing, exposing, cleaning, and the like of the photoresist, which is a conventional technical means in the field and is not described herein again.

In a preferred embodiment, as shown in fig. 7, further comprising, before forming the second dielectric layer:

s330: and carrying out oxidation treatment on the patterned bottom electrode layer to obtain a second side wall oxide layer.

It can be understood that after etching the bottom electrode layer, the bottom electrode layer is oxidized to convert the metal component in the etching by-product into oxide, so as to reduce or avoid the influence on the performance of the bottom electrode layer. The oxidation treatment may be performed using oxygen or a mixed gas containing oxygen, and for example, may be performed using a mixed gas of oxygen, argon, ozone, or the like. In other embodiments, other materials and gases that are feasible in the art may be used for the oxidation process, and the present invention is not limited thereto.

Preferably, the material of the substrate may be silicon oxide. In other embodiments, the substrate may be made of other materials available in the art, and the invention is not limited thereto.

Preferably, the material of the bottom electrode layer can be selected from heavy metals having conductive, adhesive and buffering functions, such as Ta, Ru, Pt and CuN. In other embodiments, the bottom electrode layer may be made of other materials available in the art, and the invention is not limited thereto.

Preferably, the material of the metal layer may be one metal or a combination of metals such as Ti, Au, Al, and Cu. In other embodiments, the metal layer may be made of other materials available in the art, and the invention is not limited thereto.

Preferably, the material of the first dielectric layer, the second dielectric layer and/or the third dielectric layer may be silicon oxide or silicon nitride. In other embodiments, the first dielectric layer, the second dielectric layer and/or the third dielectric layer may be made of other materials available in the art, which is not limited in the present invention.

Preferably, when the first dielectric layer, the second dielectric layer and/or the third dielectric layer are formed, a material layer of the first dielectric layer, the second dielectric layer and/or the third dielectric layer may be deposited first, and then the deposited material layer is subjected to planarization treatment to obtain the first dielectric layer, the second dielectric layer and/or the third dielectric layer.

Each layer structure may be formed sequentially on the substrate by deposition, sputtering, growth, or the like. The deposition method can be Pulsed Laser Deposition (PLD), magnetron sputtering (magnetron-sputtering), Molecular Beam Epitaxy (MBE), or Chemical Vapor Deposition (CVD). The etching mode can adopt dry etching or wet etching. In other embodiments, each layer structure may be formed by other methods, but the invention is not limited thereto.

The invention will be further illustrated by means of a specific example. As shown in fig. 8 and fig. 9A to 9G, in this example, the method of manufacturing the magnetic tunnel junction includes the steps of:

step S1: a silicon wafer with an SiO layer is used as a substrate 10, and a bottom electrode layer 12, a core layer 14 and a covering layer 16 are deposited by a magnetron sputtering method. A third dielectric layer 20 of silicon oxide is deposited on the capping layer to a thickness of 20nm to 200nm.

Step S2: the silicon oxide third dielectric layer 20 is etched using the photoresist as a mask, and the magnetic tunnel junction pattern is transferred to the first hard mask 20. The etching gas is CF4, the flow rate is 10sccm to 100sccm, the RF voltage is 100W to 500W, and the bias voltage is 50W to 150W.

Step S3: the core layer and the capping layer are etched using a first hard mask 20 to form MTJ pillars. The etching gas is Ar, the flow rate is 50sccm to 250sccm, the radio frequency voltage is 100W to 500W, and the bias voltage is 50W to 350W. And carrying out oxidation treatment on the side wall of the MTJ pillar, and oxidizing the redeposited etching by-products to form a first side wall oxide layer. A first dielectric layer 22 of silicon oxide is deposited to a thickness of 20nm to 200nm.

Step S4: the silicon oxide first dielectric layer 22 is etched using the photoresist as a mask to form a second hard mask 22. The etching gas is CF4, the flow rate is 10sccm to 100sccm, the RF voltage is 100W to 500W, and the bias voltage is 50W to 150W.

Step S5: the bottom electrode of the MTJ is etched using the second hard mask 22 with an etching gas Ar at a flow rate of 50sccm to 250sccm, a radio frequency voltage of 100W to 500W, and a bias voltage of 50W to 350W. And carrying out oxidation treatment to oxidize the redeposited etching by-products to form a second side wall oxide layer. A second dielectric layer 24 of silicon oxide is deposited to a thickness of 20nm to 300 nm.

Step S6: the MTJ and the silicon oxide dielectric layers (first dielectric layer, second dielectric layer, and third dielectric layer) on the top of the bottom electrode are etched using photoresist as a mask to form top electrode via 44 and bottom electrode vias 42a and 42 b. The etching gas is CF4, the flow rate is 10sccm to 100sccm, the RF voltage is 100W to 500W, and the bias voltage is 50W to 150W.

Step S7: the electrode pattern is transferred to the photoresist by photolithography. Depositing a Ti metal layer from 10nm to 50nm, and depositing a top electrode metal layer from 50nm to 70 nm. The wet photoresist strip strips the excess metal layer to complete the MTJ top and bottom electrode leads 32.

The preparation method of the MTJ provided by the invention effectively reduces the influence of the redeposition of the etching by-product in the dry etching on the performance of the MTJ junction, reduces the performance loss of the MTJ after the patterning of the film stack into the device and improves the yield of the MTJ. In addition, the MTJ preparation method provided by the invention has relatively low process difficulty and relatively few steps, and the process complexity and the preparation cost can be reduced by adopting the method.

Based on the same principle, the embodiment also discloses a magnetic tunnel junction unit structure. As shown in fig. 9G, the unit structure includes:

a substrate;

a bottom electrode layer formed on the substrate;

a magnetic tunnel junction formed on the bottom electrode layer;

a first dielectric layer formed on a surface comprised of the magnetic tunnel junction and the bottom electrode layer, having a bottom electrode pattern for patterning the bottom electrode layer;

a second dielectric layer formed on the surface composed of the patterned bottom electrode layer and the first dielectric layer;

and the metalized bottom electrode through hole and the metalized top electrode through hole penetrate through the second dielectric layer, the bottom electrode layer and the magnetic tunnel junction.

In a preferred embodiment, the cell structure further includes a first sidewall oxide layer obtained by oxidizing sidewalls of the magnetic tunnel junction.

In a preferred embodiment, the cell structure further includes a second sidewall oxide layer obtained by oxidizing the patterned bottom electrode layer.

Since the principle of solving the problem of the cell structure is similar to the above method, the implementation of the cell structure can be referred to the implementation of the method, and is not described herein again.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the system embodiment, since it is substantially similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.

The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.