Patent Publication Number: US-2021184108-A1

Title: Semiconductor structure and fabrication method thereof

Description:
CROSS-REFERENCES TO RELATED APPLICATION 
     This application claims the priority of Chinese Patent Application No. 201911269343.7, filed on Dec. 11, 2019, the content of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure generally relates to the field of semiconductor manufacturing and, more particularly, to a semiconductor structure and a fabrication method thereof. 
     BACKGROUND 
     An MRAM (i.e., Magnetic Random-Access Memory) is a non-volatile magnetic random-access memory. The MRAM has high-speed read and write capabilities of a static random-access memory (SRAM), high integration of a dynamic random-access memory (DRAM), and power consumption much lower than the DRAM. Compared with a flash memory (Flash), performance of the MRAM will not degrade as use time increases. Due to the above-mentioned characteristics, the MRAM is regarded as a universal memory and is considered to be able to replace the SRAM, the DRAM, an electrically erasable programmable read-only memory (EEPROM), and the Flash. 
     Different from existing random-access memory chip manufacturing technologies, data in the MRAM is not stored in a form of an electric charge or an electric current, but is stored in a magnetic state, which is sensed by measuring a resistance without disturbing the magnetic state. The MRAM uses a magnetic tunnel junction (MTJ) structure for data storage. An MRAM cell may include a transistor (1T) and a magnetic tunnel junction (MTJ) to form a memory cell. The MTJ structure at least includes two electromagnetic layers and an insulating layer for isolating the two electromagnetic layers. Electric current vertically flows or “passes” from one of the two electromagnetic layers to another of the two electromagnetic layers through the insulating layer. One of the two electromagnetic layers is a fixed magnetic layer, which fixes an electrode in one alternative direction through a strong fixed field. Another of the two electromagnetic layers is a freely rotatable magnetic layer, which holds an electrode in one of alternative directions. 
     However, there is a need to improve device performance of conventionally formed magnetic tunnel junction. 
     SUMMARY 
     One aspect of the present disclosure provides a method for forming a semiconductor structure. The method includes: providing a substrate; forming a bottom electromagnetic material film on the substrate; forming a precursor film on the bottom electromagnetic material film; and forming a first insulating film on the precursor film. 
     Optionally, the precursor film is made of a material including magnesium, aluminum, hafnium, zirconium, or a combination thereof. 
     Optionally, forming the precursor film includes: forming an insulating material film on the bottom electromagnetic material film, that the insulating material film is made of a metal oxide; and performing a modification treatment on the insulating material film to remove oxygen therefrom, to form the insulating material film into the precursor film. 
     Optionally, a thickness of the insulating material film ranges from about 0 angstroms to about 500 angstroms. 
     Optionally, the metal oxide is a material including magnesium oxide, aluminum oxide, hafnium dioxide, zirconium dioxide, or a combination thereof. 
     Optionally, forming the insulating material film includes a chemical vapor deposition process, a physical vapor deposition process, or a combination thereof. 
     Optionally, the modification treatment includes: performing a reduction treatment on the insulating material film to remove oxygen therefrom, that process parameters of the reduction treatment include: gases including hydrogen and helium, that a flow rate of the hydrogen is from about 50 SCCM to about 5000 SCCM, and a flow rate of the helium is from about 0 SCCM to about 10000 SCCM; a temperature from about 25° C. to about 150° C.; and a treatment time from about 1 second to about 120 minutes. 
     Optionally, forming the precursor film includes a chemical vapor deposition process, a physical vapor deposition process, or a combination thereof. 
     Optionally, forming the first insulating film includes a chemical vapor deposition process, a physical vapor deposition process, an atomic layer deposition process, or a combination thereof, and the first insulating film is made of a material including magnesium oxide, aluminum oxide, silicon nitride, silicon oxynitride, hafnium dioxide, zirconium dioxide, or a combination thereof. 
     Optionally, forming the first insulating film includes: performing an oxidation treatment on the precursor film to form the precursor film into the first insulating film, that a thickness of the first insulating film is less than or equal to a thickness of the precursor film; and the thickness of the first insulating film ranges from about 0 angstroms to about 500 angstroms. 
     Optionally, the first insulating film is made of a material including magnesium oxide, aluminum oxide, hafnium dioxide, zirconium dioxide, or a combination thereof. 
     Optionally, the method further includes: forming a top electromagnetic material film on the first insulating film; and before forming the top electromagnetic material film on the first insulating film, performing an annealing treatment to form the precursor film into a second insulating film, that the second insulating film is at a bottom of the first insulating film, and a temperature range of the annealing treatment is from about 300 degrees Celsius to about 400 degrees Celsius. 
     Optionally, a conductive layer is provided in the substrate, the substrate exposes a surface of the conductive layer, and the bottom electromagnetic material film is on the substrate and the surface of the conductive layer. 
     Optionally, the bottom electromagnetic material film includes: a lower electrode film on the substrate and the surface of the conductive layer, a lower composite film on the lower electrode film, and a lower electromagnetic film on the lower composite film. 
     Optionally, the lower electrode film is made of a material including copper, tungsten, aluminum, titanium, titanium nitride, tantalum, or a combination thereof; the lower composite film has a structure including a single layer structure or a composite structure; and the lower electromagnetic film is made of a material including iron, platinum, cobalt, nickel, cobalt iron boron, cobalt iron, nickel iron, lanthanum strontium manganese oxygen, or a combination thereof. 
     Optionally, when the lower composite film has the single layer structure, the lower composite film is made of a material including iron, platinum, cobalt, nickel, cobalt iron boron, cobalt iron, nickel iron, lanthanum strontium manganese oxygen, or a combination thereof, and when the lower composite film has the composite structure, the lower composite film includes a plurality of conductive layers overlapped each other, and each layer of the plurality of conductive layers is made of a material including iron, platinum, cobalt, nickel, cobalt iron boron, cobalt iron, nickel iron, lanthanum strontium manganese oxygen, or a combination thereof. 
     Optionally, the top electromagnetic material film includes: an upper electromagnetic film on the first insulating film, an upper composite film on the upper electromagnetic film, and an upper electrode film on the upper composite film. 
     Optionally, the method further includes: after forming the top electromagnetic material film, patterning the top electromagnetic material film, the first insulating film, the second insulating film, and the bottom electromagnetic material film, until a surface of the substrate is exposed, so that the patterned top electromagnetic material film forms a top electromagnetic layer, the patterned first insulating film forms a first insulating layer, the patterned second insulating film forms a second insulating layer, and the patterned bottom electromagnetic material film forms a bottom electromagnetic layer, to form a magnetic tunnel junction on the substrate. 
     Optionally, patterning the top electromagnetic material film, the first insulating film, the second insulating film, and the bottom electromagnetic material film includes: forming a patterned layer on the top electromagnetic material film, that the patterned layer exposes a portion of the top electromagnetic material film; and using the patterned layer as a mask, etching the top electromagnetic material film, the first insulating film, the second insulating film, and the bottom electromagnetic material film, until the surface of the substrate is exposed, to form the magnetic tunnel junction, that the magnetic tunnel junction includes: the bottom electromagnetic layer on the substrate, the second insulating layer on the bottom electromagnetic layer, the first insulating layer on the second insulating layer, and the top electromagnetic layer on the first insulating layer. 
     Another aspect of the present disclosure provides a semiconductor structure formed by the above-mentioned method, including: a substrate; and a magnetic tunnel junction on the substrate. The magnetic tunnel junction includes: a bottom electromagnetic layer on the substrate, a second insulating layer on the bottom electromagnetic layer, a first insulating layer on the second insulating layer, and a top electromagnetic layer on the first insulating layer. 
     Compared with existing technologies, the technical solutions of the embodiments of the present disclosure have the following beneficial effects. 
     In the method for forming the semiconductor structure provided by the technical solutions of the present disclosure, during a process of forming the first insulating film on the precursor film, since a material of the precursor film can block ions in a deposition process of forming the first insulating film from diffusing into the bottom electromagnetic material film, thereby preventing the deposition process of forming the first insulating film from affecting the bottom electromagnetic material film. At a same time, through the annealing treatment, the precursor film is formed into the second insulating film, and the second insulating film provides a material for forming a non-magnetic insulating layer in the magnetic tunnel junction. In summary, performance of the semiconductor structure formed by the method is improved. 
     Further, before forming the first insulating film, the precursor film has been formed on the bottom electromagnetic material film, so as to ensure that the precursor film can block the ions from diffusing into the bottom electromagnetic material film during the process of forming the first insulating film. 
     Further, a significance of selecting the thickness range of the insulating material film is that: if the thickness is less than about 0 angstroms, the ions can diffuse into the bottom electromagnetic material film during the deposition process of forming the first insulating film, resulting in poor performance of the formed semiconductor structure; and if the thickness is greater than about 500 angstroms, the deposition process of forming the insulating material film can still affect the bottom electromagnetic material film, which is not conducive to improving the performance of the formed semiconductor structure. 
     Further, by performing the oxidation treatment on the precursor film, the precursor film is formed into the first insulating film, and the thickness of the first insulating film is less than or equal to the thickness of the precursor film. The precursor film is used as a precursor layer to form the first insulating film, which save cost and process time. At a same time, process parameters of the oxidation treatment are controlled so that the thickness of the first insulating film is less than or equal to the thickness of the precursor film, during a process of forming the precursor film into the first insulating film. In other words, the process parameters of the oxidation treatment are controlled to ensure that the oxidation treatment of the precursor film is stopped, when a portion of the precursor film is left or the precursor film is formed into the first insulating film. Thus, influence of the oxidation treatment process on the bottom electromagnetic material film is avoided, so that the performance of the formed semiconductor structure is improved. 
     Furthermore, the annealing treatment can oxidize the material of the precursor film to form the second insulating film. The second insulating film and the first insulating film together serve as insulating layers for subsequently forming the magnetic tunnel junction. A process of oxidizing the precursor film is controlled by controlling a treatment time of the annealing treatment. Since an appropriate temperature of the annealing treatment is selected, an oxidation rate of the precursor film can be controlled. Thus, time parameters of the annealing process can be controlled, to oxidize the material of the precursor film to form the second insulating film, that is, to form the precursor film into the second insulating film with better insulating properties, while avoiding impact on the bottom electromagnetic material film, so that the performance of the formed semiconductor structure is improved. 
     Further, the temperature range of the annealing treatment is from about 300 degrees Celsius to about 400 degrees Celsius. A significance of selecting the temperature range is that: if the temperature is greater than about 400 degrees Celsius, the temperature is too high, that on one hand, it is easy to cause high temperature effects on materials, and on another hand, the temperature is too high, which is likely to cause the oxidation rate to be too fast, and is easy to cause over-oxidation of materials of the first insulating film and the second insulating film, resulting in a decrease in insulating performance of the first insulating film and the second insulating film; and if the temperature is less than about 300 degrees Celsius, the temperature is too low, resulting in too low efficiency of oxidizing the precursor film to form the second insulating film, which is not conducive to improving production efficiency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following accompanying drawings are merely examples for illustrative purposes according to various disclosed embodiments and are not intended to limit the scope of the present disclosure. 
         FIGS. 1 to 4  illustrate structures corresponding to certain stages during a fabrication process of a semiconductor structure; 
         FIGS. 5 to 15  illustrate structures corresponding to certain stages during an exemplary fabrication process of a semiconductor structure consistent with various disclosed embodiments of the present disclosure; and 
         FIG. 16  illustrates an exemplary fabrication process of a semiconductor structure consistent with various disclosed embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to exemplary embodiments of the present disclosure, which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the accompanying drawings to refer to the same or like parts. 
       FIGS. 1 to 4  illustrate structures corresponding to certain stages during a fabrication process of a semiconductor structure. 
     Referring to  FIG. 1 , a substrate  100  is provided. A conductive layer  110  is provided in the substrate  100 , and the substrate  100  exposes a surface of the conductive layer  110 . 
     Referring to  FIG. 2 , a bottom electromagnetic material film  120  is formed on the substrate  100  and the surface of the conductive layer  110 . 
     Referring to  FIG. 3 , an insulating film  130  is formed on the bottom electromagnetic material film  120 . 
     Referring to  FIG. 4 , a top electromagnetic material film  140  is formed on the insulating film  130 . 
     The bottom electromagnetic material film  120  is formed on the substrate  100  and the surface of the conductive layer  110 . The insulating film  130  is formed on the bottom electromagnetic material film  120 . The top electromagnetic material film  140  is formed on the insulating film  130 . The bottom electromagnetic material film  120 , the insulating film  130 , and the top electromagnetic material film  140  are used to form a magnetic tunnel junction. 
     However, since the insulating film  130  usually has a thickness, during a process of forming the insulating film  130 , ions in a deposition process can diffuse into the bottom electromagnetic material film  120 , resulting in influence on a material of the bottom electromagnetic material film  120 . As a result, stability of the formed magnetic tunnel junction is poor, and the performance of the such semiconducting structure needs to be improved. 
     Embodiments of the present disclosure provide a method of forming a semiconductor structure, including: providing a substrate; forming a bottom electromagnetic material film on the substrate; forming a precursor film on the bottom electromagnetic material film; forming a first insulating film on the precursor film; performing an annealing treatment to form the precursor film into a second insulating film; and forming a top electromagnetic material film on the first insulating film. The performance of the semiconductor structure formed by the method is improved. 
     To make the above objectives, features and beneficial effects of the present disclosure clearer and more understandable, various exemplary embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. 
       FIGS. 5 to 15  illustrate structures corresponding to certain stages during an exemplary fabrication process of a semiconductor structure consistent with various disclosed embodiments of the present disclosure.  FIG. 16  illustrates an exemplary fabrication process of a semiconductor structure consistent with various disclosed embodiments of the present disclosure. 
     Referring to  FIG. 5 , a substrate  200  is provided, according to S 01  in  FIG. 16 . 
     In one embodiment, a conductive layer  210  is provided in the substrate  200 , and the substrate  200  exposes a surface of the conductive layer  210 . 
     In one embodiment, the substrate  200  includes: a semiconductor substrate (not shown in  FIG. 5 ) and a dielectric layer (not shown in  FIG. 5 ) on the semiconductor substrate, that the conductive layer  210  is in the dielectric layer. 
     The semiconductor substrate is made of a semiconductor material. In one embodiment, the semiconductor substrate is made of silicon. In other embodiments, the semiconductor substrate is made of a material including silicon carbide, silicon germanium, a compound semiconductor including Group III-V elements, silicon-on-insulator (SOI), germanium-on-insulator, or a combination thereof. 
     In one embodiment, device structures are provided in the semiconductor substrate, and the device structures include structures including PMOS transistors, NMOS transistors, CMOS transistors, resistors, capacitors, inductors, or a combination thereof. 
     The dielectric layer is made of a material including silicon oxide, a low-K dielectric material, an ultra-low-K dielectric material, or a combination thereof. 
     In one embodiment, the dielectric layer is made of silicon oxide. 
     The conductive layer  210  is made of a material including copper, tungsten, aluminum, titanium, titanium nitride, tantalum, or a combination thereof. 
     In one embodiment, the conductive layer  210  is made of copper. 
     Referring to  FIG. 6 , a bottom electromagnetic material film  220  is formed on the substrate  200 , according to S 02  in  FIG. 16 . 
     In one embodiment, the bottom electromagnetic material film  220  is formed on the substrate  200  and the surface of the conductive layer  210 . 
     In one embodiment, the bottom electromagnetic material film  220  includes: a lower electrode film  221  on the substrate  200  and the surface of the conductive layer  210 , a lower composite film  222  on the lower electrode film  221 , and a lower electromagnetic film  223  on the lower composite film  222 . 
     The lower electrode film  221  is made of a material including copper, tungsten, aluminum, titanium, titanium nitride, tantalum, or a combination thereof. 
     In one embodiment, the lower electrode film  221  is made of tantalum. 
     The lower composite film  222  has a structure including a single layer structure or a composite structure. 
     In one embodiment, the lower composite film  222  has the composite structure. The lower composite film  222  includes two conductive layers overlapped each other (not shown in  FIG. 6 ), one layer of the two conductive layers is made of platinum, and another layer of the two conductive layers is made of cobalt. 
     In other embodiments, the conductive layers may also be made of a material including iron, platinum, cobalt, nickel, cobalt iron boron, cobalt iron, nickel iron, lanthanum strontium manganese oxygen, or a combination thereof. 
     The lower electromagnetic film  223  is made of a material including iron, platinum, cobalt, nickel, cobalt iron boron, cobalt iron, nickel iron, lanthanum strontium manganese oxygen, or a combination thereof. 
     In one embodiment, the lower electromagnetic film  223  has a single layer structure, and the lower electromagnetic film  223  is made of cobalt iron boron. 
     Next, a precursor film is formed on the bottom electromagnetic material film  220 , according to S 03  in  FIG. 16 .  FIGS. 7-8  illustrate alternative exemplary processes of forming the precursor film. 
     Referring to  FIG. 7 , an insulating material film  230  is formed on the bottom electromagnetic material film  220 , and the insulating material film  230  is made of a metal oxide. 
     The insulating material film  230  provides a material for subsequent formation of a precursor film. 
     A thickness of the insulating material film  230  ranges from about 0 angstroms to about 500 angstroms. 
     A preferred range of the thickness of the insulating material film  230  is from about 1 angstrom to about 100 angstroms. 
     A significance of the preferred range of the thickness of the insulating material film  230  being from about 1 angstrom to about 100 angstroms is that: if the thickness is less than about 1 angstrom, a thickness of the precursor film to be subsequently formed is too thin, and during a subsequent deposition and formation process of a first insulating film, the precursor film may not be able to block ions from diffusing into the bottom electromagnetic material film  220  at a bottom of the precursor film, resulting in poor performance of a formed semiconductor structure; and if the thickness is greater than about 100 angstroms, a process of forming the insulating material film may affect the bottom electromagnetic material film  220 , which is not conducive to improving the performance of the formed semiconductor structure. 
     The metal oxide is a material including magnesium oxide, aluminum oxide, hafnium dioxide, zirconium dioxide, or a combination thereof. 
     In one embodiment, the insulating material film  230  is made of magnesium oxide. 
     Referring to  FIG. 8 , a modification treatment is performed on the insulating material film  230  to remove oxygen therefrom, to form the insulating material film  230  into a precursor film  240 . 
     The precursor film  240  provides a material for subsequent formation of a second insulating film. 
     The modification treatment includes: performing a reduction treatment on the insulating material film  230  to remove oxygen therefrom. 
     Process parameters of the reduction treatment include: gases including hydrogen and helium, that a flow rate of the hydrogen is from about 50 SCCM to about 5000 SCCM, and a flow rate of the helium is from about 0 SCCM to about 10000 SCCM; a temperature from about 25 degrees Celsius to about 150 degrees Celsius; and a treatment time from about 1 second to about 120 minutes. 
     The precursor film  240  is made of a material including magnesium, aluminum, hafnium, zirconium, or a combination thereof. 
     In one embodiment, since the insulating material film  230  is made of magnesium oxide, the precursor film  240  formed after the modification treatment is made of magnesium. 
     Before subsequent formation of the first insulating film, the precursor film  240  has been formed on the bottom electromagnetic material film  220 , so as to ensure that during the subsequent formation of the first insulating film, the precursor film  240  can block the ions from diffusing into the bottom electromagnetic material film  220 . 
     In other embodiments, forming the precursor film  240  may also include a chemical vapor deposition process, a physical vapor deposition process, or a combination thereof. 
     Referring to  FIG. 9 , a first insulating film  250  is formed on the precursor film  240 , according to S 04  in  FIG. 16 . 
     The first insulating film  250  and the subsequently formed second insulating film together provide materials for subsequent formation of a magnetic tunnel junction. 
     Forming the first insulating film  250  includes a chemical vapor deposition process, a physical vapor deposition process, an atomic layer deposition process, or a combination thereof. 
     The first insulating film  250  is made of a material including magnesium oxide, aluminum oxide, silicon nitride, silicon oxynitride, hafnium dioxide, zirconium dioxide, or a combination thereof. 
     In one embodiment, the first insulating film  250  and the insulating material film  230  are made of a same material, which is magnesium oxide. 
     In other embodiments, forming the first insulating film includes: performing an oxidation treatment on the precursor film to form the precursor film into the first insulating film, that a thickness of the first insulating film is less than or equal to a thickness of the precursor film, and the thickness of the first insulating film ranges from about 0 angstroms to about 500 angstroms. 
     The first insulating film is made of a material including magnesium oxide, aluminum oxide, hafnium dioxide, zirconium dioxide, or a combination thereof. 
     By performing the oxidation treatment on the precursor film, the precursor film is formed into the first insulating film, and the thickness of the first insulating film is less than or equal to the thickness of the precursor film. The precursor film is used as a precursor layer to form the first insulating film, which is beneficial to saving cost and process time. At a same time, process parameters of the oxidation treatment are controlled so that the thickness of the first insulating film is less than or equal to the thickness of the precursor film, during a process of forming the precursor film into the first insulating film. In other words, the process parameters of the oxidation treatment are controlled to ensure that the oxidation treatment on the precursor film is stopped, when a portion of the precursor film is left, or the precursor film is formed into the first insulating film. As a result, influence of the oxidation treatment process on the bottom electromagnetic material film can be avoided, so that the performance of the formed semiconductor structure is improved. 
     Referring to  FIG. 10 , an annealing treatment is performed to form the precursor film  240  into a second insulating film  260 , according to S 05  in  FIG. 16 . 
     Through the annealing treatment, the material of the precursor film  240  is oxidized to form the second insulating film  260  with better insulating performance. 
     A temperature range of the annealing treatment is from about 300 degrees Celsius to about 400 degrees Celsius. 
     A significance of selecting the temperature range is that: if a temperature is greater than about 400 degrees Celsius, the temperature is too high, that on one hand, it is easy to cause high temperature effects on a material of the bottom electromagnetic material film  220  and devices in the substrate  200 , and on another hand, the temperature is too high, which is likely to cause an oxidation rate to be too fast, and is easy to cause over-oxidation of materials of the first insulating film  250  and the second insulating film  260 , resulting in a decrease in insulating performance of the first insulating film  250  and the second insulating film  260 ; and if the temperature is less than about 300 degrees Celsius, the temperature is too low, resulting in too low efficiency of oxidizing the precursor film  240  to form the second insulating film  260 , which is not conducive to improving production efficiency. 
     In one embodiment, the annealing treatment can also transform a material including an amorphous silicon oxide or a polycrystalline silicon oxide in the first insulating film  250  into a monocrystalline silicon oxide, which is beneficial to improving performance of the first insulating film  250 , thereby improving the performance of the formed semiconductor structure. 
     A process of oxidizing the precursor film  240  is controlled by controlling a treatment time of the annealing treatment. When an appropriate temperature of the annealing treatment is selected, the oxidation rate of the precursor film  240  can be controlled. Thus, time parameters of the annealing process can be controlled, to oxidize the material of the precursor film  240  to form the second insulating film  260 , that is, to form the precursor film  240  into the second insulating film  260  with better insulating properties, while avoiding impact on the bottom electromagnetic material film  220 , so that the performance of the formed semiconductor structure is improved. 
     Referring to  FIG. 11 , after the second insulating film  260  is formed, a top electromagnetic material film  270  is formed on the first insulating film  250 , according to S 06  in  FIG. 16 . 
     The top electromagnetic material film  270  includes: an upper electromagnetic film  271  on the first insulating film  250 , an upper composite film  272  on the upper electromagnetic film  271 , and an upper electrode film  273  on the upper composite film  272 . 
     The upper electromagnetic film  271  and the lower electromagnetic film  223  are made of a same material, which will not be repeated here. 
     The upper composite film  272  and the lower composite film  222  are made of a same material, which will not be repeated here. 
     The upper electrode film  273  and the lower electrode film  221  are made of a same material, which will not be repeated here. 
     In one embodiment, after forming the top electromagnetic material film  270 , the method further includes: patterning the top electromagnetic material film  270 , the first insulating film  250 , the second insulating film  260 , and the bottom electromagnetic material film  220  until a surface of the substrate  200  is exposed, so that, the patterned top electromagnetic material film forms a top electromagnetic layer, the patterned first insulating film forms a first insulating layer, the patterned second insulating film forms a second insulating layer, and the patterned bottom electromagnetic material film forms a bottom electromagnetic layer, to form a magnetic tunnel junction on the substrate.  FIGS. 12-13  illustrate alternative exemplary processes of forming the magnetic tunnel junction. 
     Referring to  FIG. 12 , a patterned layer  280  is formed on the top electromagnetic material film  270 , and the patterned layer  280  exposes a portion of the top electromagnetic material film  270 . 
     The patterned layer  280  is used as a mask for subsequent etching of the top electromagnetic material film  270 , the first insulating film  250 , the second insulating film  260 , and the bottom electromagnetic material film  220 . 
     In one embodiment, the patterned layer  280  covers the top electromagnetic material film  270  on the conductive layer  210 , so that after a patterning process, a bottom of the formed magnetic tunnel junction is in contact with the surface of the conductive layer  210  to achieve electrical connection. 
     Referring to  FIG. 13 , using the patterned layer  280  as a mask, the top electromagnetic material film  270 , the first insulating film  250 , the second insulating film  260 , and the bottom electromagnetic material film  220  are etched, until the surface of the substrate  200  is exposed, to form a magnetic tunnel junction  290 . 
     The magnetic tunnel junction  290  includes a bottom electromagnetic layer  291  on the substrate  200 , a second insulating layer  292  on the bottom electromagnetic layer  291 , a first insulating layer  293  on the second insulating layer  292 , and a top electromagnetic layer  294  on the first insulating layer  293 . 
     In one embodiment, after forming the magnetic tunnel junction  290 , the method further includes: removing the patterned layer  280 . 
     In one embodiment, the method for forming the semiconductor structure further includes: after forming the magnetic tunnel junction  290 , forming sidewall spacers on sidewall surfaces of the magnetic tunnel junction  290 , that the sidewall spacers are on the substrate.  FIGS. 14-15  illustrate exemplary processes of forming the sidewall spacers. 
     Referring to  FIG. 14 , a sidewall material film  295  is formed on the substrate  200 , and a top surface and the sidewall surfaces of the magnetic tunnel junction  290 . 
     The sidewall material film  295  provides materials for subsequent formation of sidewall spacers. 
     Forming the sidewall material film  295  includes a chemical vapor deposition process, a physical vapor deposition process, an atomic layer deposition process, or a combination thereof. 
     In one embodiment, the sidewall material film  295  is formed by the atomic layer deposition process, so that thickness uniformity of the sidewall material film  295  formed is better, and step coverage is high, which facilitates subsequent formation of sidewall spacers with a uniform thickness. 
     The sidewall material film  295  is made of a material including silicon oxide, silicon nitride, silicon carbide nitride, silicon nitride boride, silicon oxynitride, silicon oxynitride, or a combination thereof. 
     In one embodiment, the sidewall material film  295  is made of silicon nitride. 
     Referring to  FIG. 15 , the sidewall material film  295  is etched back, until the surface of the substrate  200  and the top surface of the magnetic tunnel junction  290  are exposed, to form sidewall spacers  296 . 
     The sidewall spacers  296  are used to protect the magnetic tunnel junction  290 , reduce impact on the magnetic tunnel junction  290  from subsequent processes, and improve integrity of the magnetic tunnel junction  290 , thereby improving stability of the magnetic tunnel junction  290 . 
     Since the sidewall material film  295  is made of silicon nitride, correspondingly, the sidewall spacers  296  are made of silicon nitride. 
     Correspondingly, the embodiments of the present disclosure also provide a semiconductor structure formed by the above method. 
     The embodiments disclosed herein are exemplary only. Other applications, advantages, alternations, modifications, or equivalents to the disclosed embodiments that are obvious to those skilled in the art are intended to be encompassed within the scope of the present disclosure.