JP2013145846A - Manufacturing method for tunnel magnetoresistive element and manufacturing device of tunnel magnetoresistive element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a tunnel magnetoresistive element and a manufacturing device of a tunnel magnetoresistive element capable of improving a tunnel magnetoresistance effect in a tunnel magnetoresistive element having a tunnel barrier layer.SOLUTION: A manufacturing method for a tunnel magnetoresistive element comprises the steps of: forming a first magnetic layer 13 on a substrate 11; forming a first tunnel barrier layer 141 which is an oxide of a metal element on the first magnetic layer 13; forming a diffusion suppression metal layer composed of a metal element on the first tunnel barrier layer 141; forming a second magnetic layer 15 on the diffusion suppression metal layer; and heating a laminate in which the first tunnel barrier layer 14 and the diffusion suppression metal layer are sandwiched between the first magnetic layer 13 and the second magnetic layer 15. In the step of heating the laminate, a second tunnel barrier layer 142 which is an oxide of a metal element is formed from the diffusion suppression metal layer by the oxygen diffused from the first tunnel barrier layer 141.

Description

  The technology of the present disclosure relates to a tunnel magnetoresistive element manufacturing method and a tunnel magnetoresistive element manufacturing apparatus, and in particular, a tunnel magnetoresistive element manufacturing method and a tunnel magnetoresistive element manufacturing apparatus in which a tunnel barrier layer is a metal oxide. About.

  A magnetoresistive device such as an MRAM (Magneto resistive Random Access Memory) or a magnetic sensor is equipped with a tunnel magnetoresistive element that realizes a function required for the device by a tunnel magnetoresistive effect. A tunnel magnetoresistive element in which a tunnel barrier layer is sandwiched between two magnetic layers changes the value of a current flowing through the tunnel barrier layer according to the magnetization directions of the two magnetic layers. Conventionally, metal oxides such as aluminum oxide and titanium oxide have been used as a material for forming such a tunnel barrier layer. Among them, a technique using magnesium oxide is disclosed in Patent Document 1 as a tunnel magnetoresistive element. Has been intensively studied as a technology to increase the power output.

JP 2008-098523 A

  On the other hand, as a premise that a large tunnel magnetoresistive effect is exhibited, each of the two magnetic layers requires a predetermined crystal orientation, and depending on the forming material, the tunnel barrier layer also needs a predetermined crystal orientation. It is said. For example, when iron is used as the magnetic layer and aluminum oxide is used as the tunnel barrier layer, (001) orientation is required for the iron that is the magnetic layer. Further, when a CoFeB alloy layer is used as the magnetic layer and a magnesium oxide layer is used as the tunnel barrier layer, each of the CoFeB alloy layer and the magnesium oxide layer requires (001) orientation.

  Therefore, in the tunnel magnetoresistive element forming process, the tunnel barrier layer is sandwiched between two magnetic layers for the purpose of giving crystal orientation to the tunnel barrier layer and the magnetic layer. In many cases, it is held for a certain period of time. At this time, if the tunnel barrier layer made of a metal oxide is maintained at a temperature higher than room temperature, oxygen contained in the tunnel barrier layer diffuses into the magnetic layer, and part of the magnetic layer loses crystal orientation. become. In particular, when the magnetic layer is made of a CoFeB alloy layer, the thickness of the CoFeB alloy layer becomes as thin as about 1 nm, and this oxygen diffusion becomes a serious problem.

  In addition to annealing for the purpose of manifesting the tunnel magnetoresistive effect, in the magnetoresistive device manufacturing process, the substrate on which the tunnel magnetoresistive element is mounted, such as the formation of an insulating layer that covers the entire tunnel magnetoresistive element, is placed at room temperature. In some cases, the temperature is maintained at a higher temperature for a certain period of time. Even if the annealing process for the purpose of manifesting the tunnel magnetoresistive effect is not performed, the temperature of the tunnel barrier layer is increased between the two magnetic layers. Some will lose crystal orientation. After all, whether the heating is for the purpose of developing the tunnel magnetoresistive effect or the other heating, the tunnel barrier layer is heated between the two magnetic layers, so that the output of the tunnel magnetoresistive element is increased. It is a hindrance.

  The technology of the present disclosure provides a tunnel magnetoresistive element manufacturing method and a tunnel magnetoresistive element manufacturing apparatus capable of enhancing the tunnel magnetoresistive effect in a tunnel magnetoresistive element having a tunnel barrier layer made of a metal oxide. For the purpose.

  One aspect of a method of manufacturing a tunnel magnetoresistive element according to the technology of the present disclosure includes a step of forming a first magnetic layer on a substrate, and forming a first tunnel barrier layer that is an oxide of a metal element on the first magnetic layer. A step of forming a diffusion suppression metal layer made of the metal element on the first tunnel barrier layer, a step of forming a second magnetic layer on the diffusion suppression metal layer, and the first tunnel barrier layer And heating the stacked body in which the diffusion suppressing metal layer is sandwiched between the first magnetic layer and the second magnetic layer, and in the step of heating the stacked body, the first tunnel barrier layer The second tunnel barrier layer, which is an oxide of the metal element, is formed from the diffusion suppressing metal layer by oxygen diffusing from the metal.

  According to one aspect of the tunnel magnetoresistive element manufacturing method in the technology of the present disclosure, the first tunnel barrier layer is interposed between the first tunnel barrier layer and the second magnetic layer in the step of heating the stacked body. A diffusion suppressing metal layer made of the same metal element as that constituting the metal is sandwiched. Therefore, when oxygen contained in the first tunnel barrier layer diffuses toward the second magnetic layer, the oxidation of the diffusion suppressing metal layer proceeds first before the oxidation of the second magnetic layer proceeds. Therefore, even if the stacked body is heated to such an extent that oxygen diffuses from the first tunnel barrier layer, oxygen diffused from the first tunnel barrier layer is first consumed for oxidation of the diffusion suppressing metal layer. As a result, since the oxidation of the second magnetic layer can be suppressed, it is possible to suppress the tunnel magnetoresistive effect from being lowered due to the oxidation of the second magnetic layer.

  In another aspect of the tunnel magnetoresistive element manufacturing method according to the technique of the present disclosure, in the step of forming the diffusion suppression metal layer, the diffusion suppression metal layer is formed thinner than the first tunnel barrier layer.

  When the amount of oxygen diffusing from the first tunnel barrier layer is small compared to the amount of oxygen required for the entire oxidation of the diffusion suppressing metal layer, the gap between the first tunnel barrier layer and the second magnetic layer is reduced. In this case, a metal element that is not oxidized remains in addition to the second tunnel barrier layer. If such a metal element remains, the tunnel magnetoresistive effect is reduced as compared with the case where all of the metal layer is oxidized.

  In this regard, according to another aspect of the method of manufacturing a tunnel magnetoresistive element in the technology of the present disclosure, the diffusion suppression metal layer is formed thinner than the first tunnel barrier layer. Therefore, when the diffusion suppression metal layer has the same thickness as the first tunnel barrier layer, or when the diffusion suppression metal layer is thicker than the first tunnel barrier layer, the metal element that is not oxidized is less than the first tunnel barrier layer. And remaining between the first magnetic layer and the second magnetic layer can be suppressed. Therefore, it is possible to suppress a decrease in the tunnel magnetoresistance effect due to the fact that the metal element of the diffusion suppressing metal layer is not oxidized.

  In another aspect of the tunnel magnetoresistive element manufacturing method according to the technique of the present disclosure, the step of forming the first tunnel barrier layer includes a step of forming a barrier metal layer made of the metal element on the first magnetic layer. And oxidizing the barrier metal layer to form the first tunnel barrier layer.

  In the method of forming the metal oxide on the first magnetic layer, the metal oxide itself is deposited on the first magnetic layer, and the metal element constituting the metal oxide is deposited on the first magnetic layer. And a method of oxidizing the metal element later. Here, in the method of depositing the metal oxide itself on the first magnetic layer, when the metal oxide itself is deposited, the amount of the metal element and the amount of oxygen, that is, elements having different physical and chemical characteristics from each other. At the same time on the first magnetic layer. On the other hand, if the metal element is deposited on the first magnetic layer and then the metal element is oxidized, the amount of the metal element and the amount of oxygen in the process of forming the tunnel barrier layer are the same as those on the first magnetic layer. It changes specially.

  In this regard, according to another aspect of the method of manufacturing a tunnel magnetoresistive element in the technology of the present disclosure, first, the barrier metal layer is formed on the first magnetic layer, and then the barrier metal layer is oxidized. Thus, the first tunnel barrier layer is formed. Therefore, since the amount of metal element and the amount of oxygen change significantly on the first magnetic layer, the composition of the first tunnel barrier layer is different from the case where the amount of metal element and the amount of oxygen change simultaneously. Adjustment becomes easy.

  Further, even when the barrier metal layer is excessively oxidized, excess oxygen is consumed by the diffusion suppressing metal layer. Therefore, as described above, the method in which the diffusion suppressing metal layer is formed in the first tunnel barrier layer, in addition to suppressing the tunnel magnetoresistive effect from being lowered by the oxidation of the second magnetic layer, Regarding the error of the degree of oxidation with respect to the metal layer, the allowable range can be increased.

  In another aspect of the tunnel magnetoresistive element manufacturing method according to the technique of the present disclosure, the metal element is magnesium, and the step of heating the stacked body crystallizes the oxidized barrier metal layer by heating. .

  According to another aspect of the method of manufacturing a tunnel magnetoresistive element in the technology of the present disclosure, magnesium oxide which is a material for forming the first tunnel barrier layer and the second tunnel barrier layer is crystallized by a step of heating the stacked body. The Therefore, compared with the case where the process of crystallizing these magnesium oxides and the process of heating the laminated body are carried out, the number of processes required for the tunnel magnetoresistive element manufacturing method can be reduced. It will be possible.

  In another aspect of the tunnel magnetoresistive element manufacturing method according to the technique of the present disclosure, the step of forming the first magnetic layer includes, as the first magnetic layer, a CoFeB having a film thickness of 0.6 nm to 2.5 nm. In the step of forming the alloy layer and forming the second magnetic layer, a CoFeB alloy layer having a thickness of 0.6 nm to 2.5 nm is used as the second magnetic layer.

  In a tunnel magnetoresistive element in which two magnetic layers are CoFeB alloy layers and a tunnel barrier layer sandwiched between these magnetic layers is a magnesium oxide layer, the thickness of the magnetic layer is 0.6 nm to 2.5 nm. In addition, a perpendicular magnetization type magnetoresistance effect is exhibited. At this time, if a part of a very thin magnetic layer of 0.6 nm or more and 2.5 nm or less is oxidized, the tunnel magnetic field is compared with the case where a part of the magnetic layer exceeding 2.5 nm is oxidized. The degree of decrease in the resistance effect is significant.

  In this regard, according to another aspect of the method of manufacturing a tunnel magnetoresistive element in the technology of the present disclosure, the thickness of each of the two magnetic layers is 0.6 nm or more and 2.5 nm or less. It becomes possible to manufacture a tunnel magnetoresistive element. Since the oxidation of the very thin second magnetic layer is suppressed as described above, the effect of suppressing the tunnel magnetoresistive effect from being lowered as described above becomes remarkable.

  One aspect of the tunnel magnetoresistive element manufacturing apparatus according to the technology of the present disclosure includes a transport unit that transports a substrate, a first magnetic layer forming unit that forms a first magnetic layer, and a second magnetic layer that forms a second magnetic layer. A layer forming unit, a barrier layer forming unit that forms a tunnel barrier layer that is an oxide of a metal element, a metal layer forming unit that forms a diffusion-inhibiting metal layer made of the metal element, and the transport of the transport unit A laminated body comprising the first magnetic layer, the second magnetic layer, the tunnel barrier layer, and the diffusion suppression metal layer is heated, and the control unit includes the first magnetic layer. The substrate is transported in the order of a layer forming part, the barrier layer forming part, the metal layer forming part, and the second magnetic layer forming part to form the stacked body.

  According to one aspect of the tunnel magnetoresistive element manufacturing apparatus in the technique of the present disclosure, the same metal element as the metal element constituting the first tunnel barrier layer is interposed between the first tunnel barrier layer and the second magnetic layer. A diffusion suppressing metal layer is sandwiched. Then, the stacked body is heated in a state where the diffusion suppressing metal layer is interposed between the first tunnel barrier layer and the second magnetic layer. Therefore, when oxygen contained in the first tunnel barrier layer is diffused toward the second magnetic layer by heating, the oxidation of the diffusion suppressing metal layer proceeds before the oxidation of the second magnetic layer proceeds. . Therefore, even if the stacked body is heated to such an extent that oxygen diffuses from the first tunnel barrier layer, such oxygen is consumed for the oxidation of the diffusion suppressing metal layer, so that the oxidation of the second magnetic layer can be suppressed. Therefore, it is possible to suppress a decrease in magnetoresistive effect due to oxidation of the second magnetic layer.

  In another aspect of the tunnel magnetoresistive element manufacturing apparatus according to the technique of the present disclosure, the metal layer forming portion is a first metal layer forming portion, and the barrier layer forming portion is made of the metal element. A second metal layer forming portion for forming the barrier metal layer and a metal layer oxidizing portion for oxidizing the barrier metal layer, and the first metal layer forming portion and the second metal layer forming portion are the same. is there.

  An example of the configuration of the barrier layer forming portion that forms the metal element oxide on the first magnetic layer is a configuration in which the metal oxide itself is deposited on the first magnetic layer. In addition, the structure in which the oxide of the metal element is formed on the first magnetic layer includes a structure having a formation part for forming the metal element on the first magnetic layer and an oxidation part for oxidizing the metal element. It is done. Here, in the configuration in which the metal oxide itself is deposited on the first magnetic layer, when the metal oxide itself is deposited, the amount of the metal element and the amount of oxygen, that is, elements having different physical and chemical characteristics from each other. At the same time on the first magnetic layer. On the other hand, if the metal element is deposited on the first magnetic layer and then the metal element is oxidized, the amount of the metal element and the amount of oxygen in the process of forming the tunnel barrier layer are on the first magnetic layer. It changes specially.

  In this regard, according to another aspect of the tunnel magnetoresistive element manufacturing apparatus in the technology of the present disclosure, first, the second metal layer forming unit forms the barrier metal layer on the first magnetic layer, and the metal layer oxidation is performed. The portion oxidizes the barrier metal layer. Therefore, since the amount of metal element and the amount of oxygen change significantly on the first magnetic layer, the composition of the first tunnel barrier layer is different from the case where the amount of metal element and the amount of oxygen change simultaneously. Adjustment becomes easy. In addition, since the first metal layer forming portion and the second metal layer forming portion are the same, the first metal layer forming portion and the second metal layer forming portion are different from each other in the configuration, It is possible to simplify the configuration of the tunnel magnetoresistive element manufacturing apparatus.

It is an element block diagram which shows an example of the layer structure of the tunnel magnetoresistive element manufactured by 1st Embodiment of the manufacturing method of the tunnel magnetoresistive element in the technique of this indication. It is an apparatus block diagram which shows the apparatus structure of the manufacturing apparatus of the tunnel magnetoresistive element in 1st Embodiment. It is an electric block diagram which shows the electrical constitution of the manufacturing apparatus of the tunnel magnetoresistive element in 1st Embodiment. It is a flowchart which shows the flow of each manufacturing process of the manufacturing method of the tunnel magnetoresistive element in 1st Embodiment. The relationship between the film thickness of the 2nd magnesium layer and element resistance value of the tunnel magnetoresistive element manufactured with the manufacturing method of the tunnel magnetoresistive element in 1st Embodiment, and the relationship between a 2nd magnesium layer and magnetoresistive ratio are shown. It is a graph. It is a test example regarding the manufacturing method of the tunnel magnetoresistive element in 1st Embodiment, Comprising: It is a graph which shows the relationship between a substrate temperature and the film thickness of a 1st magnesium layer. It is a graph which shows the relationship between the element resistance value of the tunnel magnetoresistive element manufactured by the manufacturing method of the tunnel magnetoresistive element in 1st Embodiment, and substrate temperature, and the relationship between magnetoresistive ratio and substrate temperature. It is a flowchart which shows the flow of each manufacturing process in 2nd Embodiment of the manufacturing method of the tunnel magnetoresistive element in the technique of this indication.

(First embodiment)

A tunnel magnetoresistive element manufacturing method and a tunnel magnetoresistive element manufacturing apparatus according to a first embodiment of the technology of the present disclosure will be described below with reference to FIGS. First, the layer structure of a tunnel magnetoresistive element manufactured using the tunnel magnetoresistive element manufacturing method according to the technique of the present disclosure will be described.
[Tunnel magnetoresistive element]

  As shown in FIG. 1, in the tunnel magnetoresistive element, a buffer layer 12, a first magnetic layer 13, a tunnel barrier layer 14, a second magnetic layer 15, and a capping layer 16 are stacked in this order on one side of a substrate 11. It has an element structure.

  The substrate 11 is a substrate on which various active elements and wirings for connecting the active elements and the tunnel magnetoresistive elements are formed. As the base material of the substrate 11, ceramics such as silicon and glass are applied.

  The buffer layer 12 is a layer for promoting smooth and uniform crystallization in the first magnetic layer 13. For the buffer layer 12, for example, a stacked structure in which a tantalum layer (Ta layer 12a), a ruthenium layer (Ru layer 12b), and a tantalum layer (Ta layer 12c) are stacked in this order is applied. Incidentally, for example, the thickness of the Ta layer 12a is 5 nm, the thickness of the Ru layer 12b is 21 nm, and the thickness of the Ta layer 12c is 5 nm.

The first magnetic layer 13 is a ferromagnetic layer whose magnetization direction is fixed. When the tunnel magnetoresistive element is an in-plane magnetization type, the magnetization direction of the first magnetic layer 13 is parallel to one side surface of the substrate 11. On the other hand, when the tunnel magnetoresistive element is of a perpendicular magnetization type, the magnetization direction of the first magnetic layer 13 is parallel to the normal direction to one side surface of the substrate 11. For example, a cobalt iron boron alloy crystal (CoFeB alloy crystal) having (001) orientation is applied to the first magnetic layer 13. Incidentally, the composition of the CoFeB alloy crystal is, for example, 0.2 ≦ x ≦ 0.4 and 0.4 ≦ y ≦ 0.9 in a composition formula expressed as Co _x Fe _y B _(1-xy). Fulfill. In addition to the CoFeB alloy crystal, a CoFeB alloy system, that is, an alloy in which phosphorus or carbon is added to the CoFeB alloy is applied to the first magnetic layer 13. In addition to the CoFeB alloy system, a ferromagnetic material containing at least one of cobalt (Co), nickel (Ni), and iron (Fe), such as CoFe or FeNi, is applied to the first magnetic layer 13. The film thickness of the first magnetic layer 13 is preferably 0.6 nm or more and 2.5 nm or less, for example, to ensure perpendicular magnetization.

  The tunnel barrier layer 14 is a nonmagnetic insulating layer made of a metal oxide sandwiched between the first magnetic layer 13 and the second magnetic layer 15. The tunnel barrier layer 14 includes a first tunnel barrier layer 141 in contact with the first magnetic layer 13 and a second tunnel barrier layer 142 sandwiched between the first tunnel barrier layer 141 and the second magnetic layer 15. Each of the first tunnel barrier layer 141 and the second tunnel barrier layer 142 is formed of an oxide of the same metal element, and for example, a magnesium oxide crystal (MgO crystal) having a (001) orientation or an amorphous material is used. Quality aluminum oxide is applied. From the viewpoint of obtaining a high magnetoresistance ratio, each of the first tunnel barrier layer 141 and the second tunnel barrier layer 142 is preferably an MgO crystal.

  The first tunnel barrier layer 141 is formed by a metal oxide layer obtained by oxidation of a barrier metal layer, which is a metal layer formed by sputtering using a metal target, or by sputtering using a metal oxide target. A metal oxide layer. In contrast, the second tunnel barrier layer 142 is a metal oxide layer in which a diffusion suppression metal layer that is a metal layer stacked on the second tunnel barrier layer 142 is oxidized by oxygen diffused from the first tunnel barrier layer 141. It is.

  In each of the first tunnel barrier layer 141 and the second tunnel barrier layer 142, the composition ratio of the number of oxygen atoms to the number of metal atoms is the composition ratio of the second tunnel barrier layer 142. The composition ratio is equal to or smaller than the composition ratio of the first tunnel barrier layer 141. The boundary between the first tunnel barrier layer 141 and the second tunnel barrier layer 142 is virtually determined based on the difference between the formation process of the first tunnel barrier layer 141 and the formation process of the second tunnel barrier layer 142. Is.

  In view of the function of the first tunnel barrier layer 141 in the manufacturing process of the tunnel magnetoresistive element, the second tunnel barrier layer 142 is preferably thinner than the first tunnel barrier layer 141. For example, when the first tunnel barrier layer 141 and the second tunnel barrier layer 142 are made of MgO, the second tunnel barrier layer 142 is preferably 0.2 nm to 0.6 nm, and the first tunnel barrier layer 141 is 0.8 nm. It is preferable that

The second magnetic layer 15 is a ferromagnetic layer that reverses its magnetization direction to be parallel and antiparallel to the magnetization direction of the first magnetic layer 13. For example, a CoFeB alloy crystal having (001) orientation is applied to the second magnetic layer 15. Incidentally, the composition of the CoFeB alloy crystal is, for example, 0.2 ≦ x ≦ 0.4 and 0.4 ≦ y ≦ 0.9 in a composition formula expressed as Co _x Fe _y B _(1-xy). Fulfill. In addition to the CoFeB alloy crystal, a CoFeB alloy system, that is, an alloy in which phosphorus or carbon is added to the CoFeB alloy is applied to the second magnetic layer 15. In addition to the CoFeB alloy system, a ferromagnetic material containing at least one of cobalt (Co), nickel (Ni), and iron (Fe), such as CoFe or FeNi, is applied to the first magnetic layer 13. The film thickness of the first magnetic layer 13 is preferably 0.6 nm or more and 2.5 nm or less, for example, to ensure perpendicular magnetization.

  The capping layer 16 is a layer that stabilizes the electrical connection between the second magnetic layer 15 and the wiring and promotes smooth and uniform crystallization of the second magnetic layer 15. For the capping layer 16, for example, a stacked structure in which a Ta layer 16a and a Ru layer 16b are stacked in this order from the second magnetic layer 15 side is applied. Incidentally, for example, the thickness of the Ta layer 16a is 5 nm, and the thickness of the Ru layer 16b is 10 nm.

  When an external magnetic field is applied to the tunnel magnetoresistive element from a state in which the magnetization direction of the first magnetic layer 13 and the magnetization direction of the second magnetic layer 15 are parallel to each other, the magnetization direction of the first magnetic layer 13 While the magnetization direction of the second magnetic layer 15 is reversed according to the external magnetic field. Thereby, the magnetization directions in the first magnetic layer 13 and the second magnetic layer 15 are switched from the parallel state to the antiparallel state.

Here, when the magnetization direction of the first magnetic layer 13 and the magnetization direction of the second magnetic layer 15 are in a parallel state, the magnetization direction of the first magnetic layer 13 and the magnetization direction of the second magnetic layer 15 are opposite to each other. Compared with the parallel case, the tunnel barrier in the tunnel barrier layer 14 is small. Therefore, the electrical resistance between the first magnetic layer 13 and the second magnetic layer 15 is small in the parallel state and large in the antiparallel state. Therefore, it is detected whether the magnetization direction of the first magnetic layer 13 and the magnetization direction of the second magnetic layer 15 are in a parallel state or an anti-parallel state based on the magnitude of the current flowing through the tunnel magnetoresistive element. It becomes possible.
[Tunnel magnetoresistive element manufacturing equipment]

  Next, a tunnel magnetoresistive element manufacturing apparatus according to the technique of the present disclosure will be described with reference to FIGS. First, the apparatus configuration of each forming unit constituting the tunnel magnetoresistive element manufacturing apparatus will be described with reference to FIG.

  The tunnel magnetoresistive element manufacturing apparatus is a cluster apparatus having a transfer chamber 20 as a transfer unit on which a substrate transfer robot 20R for transferring a substrate 11 is mounted. Seven vacuum chambers are connected to the periphery of the transfer chamber 20 so as to communicate with each other.

  In the loading / unloading chamber 21, a loading / unloading robot 21 </ b> R for transporting the substrate 11 is mounted. The carry-in / out robot 21R carries the substrate 11 before the tunnel magnetoresistive element is formed into the transfer chamber 20 from the outside, and also carries the substrate 11 formed with the tunnel magnetoresistive element out of the transfer chamber 20 to the outside.

  The heat treatment chamber 22 is equipped with a heat treatment heater 22H that heats the substrate 11 carried from the transfer chamber 20 to a predetermined temperature. The heat treatment chamber 22 raises the temperature of the substrate 11 carried from the transfer chamber 20 by heating the heat treatment heater 22 </ b> H, and removes the gas adsorbed on the surface of the substrate 11 from the substrate 11 by raising the temperature of the substrate 11. It promotes crystallization of the above amorphous film.

  The cleaning chamber 23 is equipped with a cleaning plasma source 23P for generating an inert gas plasma. The cleaning chamber 23 irradiates the plasma generated by the cleaning plasma source 23 </ b> P onto the substrate 11 carried from the transfer chamber 20, and the oxide layer which is the surface layer of the substrate 11 is removed by the plasma irradiation.

  A first cathode 24 </ b> C having three targets T is mounted on the first sputter chamber 24. The first sputter chamber 24 deposits particles emitted from the targets T on the substrate 11 loaded from the transfer chamber 20 by applying high-frequency voltages to the three targets T separately. For the target T mounted in the first sputtering chamber 24, a target made of the constituent material of the buffer layer 12 and the capping layer 16, for example, a Ta target is applied.

  The second sputter chamber 25 is a film forming chamber constituting the first magnetic layer forming part and the second magnetic layer forming part. In the second sputtering chamber 25, a second cathode 25C having three targets T is mounted. The second sputtering chamber 25 applies a DC voltage to each of the three targets T to deposit particles emitted from each target T on the substrate 11 carried from the transfer chamber 20. Targets T mounted in the second sputter chamber 25 include targets made of constituent materials of the buffer layer 12, the first magnetic layer 13, the second magnetic layer 15, and the capping layer 16, such as a CoFeB alloy target and a Ru target. Applied.

  The third sputter chamber 26 is a film forming chamber constituting a barrier layer forming part and a metal layer forming part. A third cathode 26 </ b> C having three targets T is mounted on the third sputter chamber 26. The third sputter chamber 26 deposits particles emitted from the targets T on the substrate 11 carried from the transfer chamber 20 by applying a DC voltage to the three targets T separately. A target made of a material constituting the tunnel barrier layer 14, for example, an Mg target, is applied to the target T mounted in the third sputtering chamber 26.

The oxidation chamber 28 is a plasma processing chamber that constitutes the metal layer oxidation portion. The oxidation chamber 28 is equipped with an oxidation plasma source 28P that generates active oxygen such as oxygen plasma and oxygen radicals, and an oxidation heater 28H that heats the substrate 11. The oxidation chamber 28 oxidizes the surface of the substrate 11 by heating the substrate 11 carried in from the transfer chamber 20 by the oxidation heater 28 </ b> H and applying plasma to the substrate 11 by the oxidation plasma source 28 </ b> P.
Next, an electrical configuration of the tunnel magnetoresistive element manufacturing apparatus will be described with reference to FIG. 3 focusing on the control device 30 included in the manufacturing apparatus.

  The control device 30 includes a control unit 30A mainly composed of a microcomputer having a CPU, ROM, and RAM, a storage unit 30B composed of a large-capacity storage device such as a hard disk device, and input of input signals from the outside. An input / output unit 30C that performs processing and output processing of output signals to the outside. The storage unit 30B stores a manufacturing program for driving each vacuum chamber of the tunnel magnetoresistive element manufacturing apparatus to manufacture the tunnel magnetoresistive element. The control unit 30A reads and executes the manufacturing program stored in the storage unit 30B, and generates a control signal for controlling the driving mode of each vacuum chamber according to the manufacturing program.

  An input device 31 serving as a human interface is connected to the control device 30. The input device 31 outputs data related to the transport path of the substrate 11 and data related to processing conditions in each vacuum chamber to the control device 30. The input / output unit 30C performs input processing of various data output from the input device 31, and the control unit 30A stores various data after input processing in the storage unit 30B through the input processing of the input / output unit 30C. .

  A substrate transport robot drive unit 20D and a carry-in / out robot drive unit 21D are connected to the control device 30. The control device 30 outputs a control signal for controlling the driving mode of the substrate transfer robot 20R to the substrate transfer robot driving unit 20D, and loads a control signal for controlling the driving mode of the loading / unloading robot 21R. Output to the exit robot drive unit 21D. Then, the substrate transport robot drive unit 20D generates a drive signal for driving the substrate transport robot 20R according to the control signal from the control device 30, and outputs the drive signal to the substrate transport robot 20R. Further, the carry-in / out robot drive unit 21D generates a drive signal for driving the carry-in / out robot 21R in accordance with a control signal from the control device 30, and outputs the drive signal to the carry-in / out robot 21R.

  The control device 30 is connected to a heat treatment heater driving unit 22D and a cleaning plasma source driving unit 23D. The control device 30 outputs a control signal for controlling the drive mode of the heat treatment heater 22H to the heat treatment heater drive unit 22D, and outputs a control signal for controlling the drive mode of the cleaning plasma source drive unit 23D. Output to the cleaning plasma source driving unit 23D. Then, the heat treatment heater drive unit 22D generates a drive signal for driving the heat treatment heater 22H according to a control signal from the control device 30, and outputs the drive signal to the heat treatment heater 22H. Further, the cleaning plasma source driving unit 23D generates a drive signal for driving the cleaning plasma source 23P in accordance with a control signal from the control device 30, and outputs it to the cleaning plasma source 23P.

  A first cathode drive unit 24D, a second cathode drive unit 25D, and a third cathode drive unit 26D are connected to the control device 30. The control device 30 outputs a control signal for controlling the driving mode of the first cathode 24C to the first cathode driving unit 24D. Further, the control device 30 outputs a control signal for controlling the driving mode of the second cathode 25C to the second cathode driving unit 25D, and a control signal for controlling the driving mode of the third cathode 26C. Is output to the third cathode driving unit 26D. Then, each of the first cathode driving unit 24D, the second cathode driving unit 25D, and the third cathode driving unit 26D corresponds to the first cathode 24C, the second cathode 25C, and the second cathode according to the control signal from the control device 30. A drive signal for driving the three cathodes 26C is generated and output.

The control device 30 is connected to an oxidation plasma source drive unit 28D and an oxidation heater drive unit 28G. The control device 30 outputs a control signal for controlling the driving mode of the oxidation plasma source 28P to the oxidation plasma source driving unit 28D, and outputs a control signal for controlling the driving mode of the oxidation heater 28H. Output to the drive unit 28G. The oxidation plasma source drive unit 28D generates a drive signal for driving the oxidation plasma source 28P in accordance with a control signal from the control device 30, and outputs the drive signal to the oxidation plasma source 28P. Further, the oxidation heater drive unit 28G generates a drive signal for driving the oxidation heater 28H in accordance with a control signal from the control device 30, and outputs the drive signal to the oxidation heater 28H.
[Method of manufacturing tunnel magnetoresistive element]

Next, a tunnel magnetoresistive element manufacturing method using the tunnel magnetoresistive element manufacturing apparatus described above will be described with reference to FIG. In the present embodiment, a method for manufacturing a tunnel magnetoresistive element having the following layer structure is exemplified.
Buffer layer 12: Ta / Ru / Ta
First magnetic layer 13: CoFeB
Tunnel barrier layer 14: MgO
Second magnetic layer 15: CoFeB
-Capping layer 16: Ta / Ru / Ta

  When the control device 30 starts executing the manufacturing program, first, the control device 30 reads the substrate transport path and the processing conditions of each vacuum chamber. Next, the control device 30 drives the substrate 11 in the loading / unloading chamber 21 to the heat treatment chamber 22 by driving the loading / unloading robot 21R by the loading / unloading robot drive unit 21D and driving the substrate transfer robot 20R by the substrate transfer robot driving unit 20D. Transport to. Subsequently, the control device 30 removes the gas adsorbed on the surface of the substrate 11 from the surface of the substrate 11 by driving the heat treatment heater 22H by the heat treatment heater driving unit 22D. For example, the control device 30 removes moisture from the surface of the substrate 11 by heating the substrate 11 to 150 ° C.

  When the gas is removed from the surface of the substrate 11, the control device 30 transfers the substrate 11 in the heat treatment chamber 22 to the cleaning chamber 23 by driving the substrate transfer robot 20 </ b> R by the substrate transfer robot drive unit 20 </ b> D. Subsequently, the control device 30 removes the oxide layer that is the surface layer of the substrate 11 by driving the cleaning plasma source 23P by the cleaning plasma source driving unit 23D. For example, the control device 30 removes the oxide layer that is the surface layer of the substrate 11 by sputtering the surface layer of the substrate 11 with plasma generated from argon gas (step S11).

  When the oxide layer, which is the surface layer of the substrate 11, is removed, the control device 30 drives the substrate transport robot 20R by the substrate transport robot drive unit 20D to move the substrate 11 in the cleaning chamber 23 into the first sputter chamber 24 and the second sputter chamber 24. The chamber 25 and the first sputtering chamber 24 are transferred in this order. The control device 30 forms the Ta layer 12a by driving the first cathode 24C by the first cathode driving unit 24D, forms the Ru layer 12b by driving the second cathode 25C by the second cathode driving unit 25D, and The Ta layer 12c is formed by driving the first cathode 24C by the one cathode driving unit 24D. Thereby, the control apparatus 30 forms the buffer layer 12 which consists of Ta layer 12a, Ru layer 12b, and Ta layer 12c on the board | substrate 11 (step S12).

  When the buffer layer is formed, the control device 30 transfers the substrate 11 in the first sputtering chamber 24 to the second sputtering chamber 25 by driving the substrate transfer robot 20R by the substrate transfer robot driving unit 20D. And the control apparatus 30 forms an amorphous CoFeB alloy layer as a 1st magnetic layer by the drive of 2nd cathode 25C by 2nd cathode drive part 25D. For example, the control device 30 sputters the target T made of a CoFeB alloy to form a CoFeB alloy layer having a thickness of 1 nm (step S13).

  When the first magnetic layer is formed, the control device 30 transfers the substrate 11 in the first sputtering chamber 24 to the third sputtering chamber 26 by driving the substrate transfer robot 20R by the substrate transfer robot driving unit 20D. Then, the control device 30 forms the amorphous Mg layer as a barrier metal layer by driving the third cathode 26C by the third cathode driving unit 26D. For example, the control device 30 sputters the target T made of Mg to form an Mg layer having a thickness of 0.8 nm (step S14).

  When the barrier metal layer is formed, the control device 30 transfers the substrate 11 in the third sputtering chamber 26 to the oxidation chamber 28 by driving the substrate transfer robot 20R by the substrate transfer robot drive unit 20D. The control device 30 heats the substrate 11 by driving the oxidation heater 28H by the oxidation heater driving unit 28G, and oxidizes the Mg layer by driving the oxidation plasma source 28P by the oxidation plasma source driving unit 28D. Thereby, the control device 30 forms an amorphous MgO layer as the first tunnel barrier layer 141. For example, the control device 30 performs heating of the Mg layer to 150 ° C. or less and irradiation of the oxygen plasma to the Mg layer to form the MgO layer (step S15).

  When the first tunnel barrier layer 141 is formed, the control device 30 transfers the substrate 11 in the oxidation chamber 28 to the third sputtering chamber 26 by driving the substrate transfer robot 20R by the substrate transfer robot drive unit 20D. And the control apparatus 30 forms Mg layer as a diffusion suppression metal layer by the drive of the 3rd cathode 26C by 3rd cathode drive part 26D. For example, the control device 30 sputters the target T made of Mg to form a Mg layer having a thickness of 0.4 nm (step S16).

  When the diffusion suppressing metal layer is formed, the control device 30 transfers the substrate 11 in the third sputtering chamber 26 to the second sputtering chamber 25 by driving the substrate transfer robot 20R by the substrate transfer robot driving unit 20D. And the control apparatus 30 forms the CoFeB alloy layer as a 2nd magnetic layer by the drive of the 2nd cathode 25C by 2nd cathode drive part 25D. For example, the control device 30 sputters the target T made of a CoFeB alloy to form a CoFeB alloy layer having a thickness of 1 nm (step S17).

  When the second magnetic layer is formed, the control device 30 drives the substrate transport robot 20R by the substrate transport robot drive unit 20D to move the substrate 11 in the second sputter chamber 25 to the first sputter chamber 24 and the second sputter chamber. 25 and the first sputter chamber 24 are transferred in this order. Then, the control device 30 forms the Ta layer 16a by driving the first cathode 24C by the first cathode driving unit 24D, and forms the Ru layer 16b by driving the second cathode 25C by the second cathode driving unit 25D. Thereby, the control apparatus 30 forms the capping layer 16 which consists of Ta layer 16a and Ru layer 16b on the board | substrate 11 (step S18).

When the capping layer 16 is formed, the control device 30 transfers the substrate 11 in the first sputter chamber 24 to the heat treatment chamber 22 by driving the substrate transfer robot 20R by the substrate transfer robot drive unit 20D. Then, the control device 30 promotes crystallization of the amorphous film formed on the substrate 11 by driving the heat treatment heater 22H by the heat treatment heater driving unit 22D. For example, the substrate 11 is held at 360 ° C. for 1 hour in an atmosphere with a magnetic field (step S19). Thereby, the first tunnel barrier layer 141 becomes a crystal having (001) orientation, and accordingly, the CoFeB alloy layer as the first magnetic layer 13 and the CoFeB alloy layer as the second magnetic layer 15 are also (001) oriented. It becomes the crystal | crystallization which has.
[Example 1]

  Next, FIG. 5 shows the relationship between the film thickness of the diffusion suppressing metal layer and the element resistance value of the tunnel magnetoresistive element, and the relationship between the film thickness of the diffusion suppressing metal layer and the magnetoresistance ratio of the tunnel magnetoresistive element. The description will be given with reference.

Using the tunnel magnetoresistive element manufacturing method described above, a tunnel magnetoresistive element of Example 1 having the following layer structure was obtained. At this time, the thickness of the Mg layer as the barrier metal layer was maintained at 0.8 nm, and the thickness of the Mg layer as the diffusion suppression metal layer was changed to 0.2 nm, 0.4 nm, and 0.6 nm. The element resistance value (RA value) and the magnetoresistance ratio (MR ratio) were measured for each of the three types of tunnel magnetoresistive elements having different thicknesses of the diffusion suppression metal layers.
Buffer layer 12: Ta (5nm) / Cu (20nm) / Ta (5nm)
First magnetic layer 13: CoFe (2.5 nm) / Ru (0.8 nm) / CoFeB (2.5 nm)
Tunnel barrier layer 14: MgO
-Barrier metal layer: Mg
・ Diffusion suppression metal layer: Mg
Second magnetic layer 15: CoFeB (3.0 nm)
-Capping layer 16: Ta (5nm) / Ru (12nm)

As shown in FIG. 5, the element resistance value of the tunnel magnetoresistive element is lowest when the thickness of the diffusion suppression metal layer is 0.2 nm, and the thickness of the diffusion suppression metal layer is 0.4 nm. The highest. Further, the magnetoresistive ratio of the tunnel magnetoresistive element is the lowest when the thickness of the diffusion suppressing metal layer is 0.2 nm, and the highest when the thickness of the diffusion suppressing metal layer is 0.4 nm. The film thickness dependence of the element resistance value and the film thickness dependence of the magnetoresistance ratio show the following two tendencies.
The oxidation of the second magnetic layer 15 is suppressed as the thickness of the diffusion suppressing metal layer increases.
-The smaller the thickness of the diffusion suppressing metal layer, the less the oxidation of the diffusion suppressing metal layer.

Even if the barrier metal layer is oxidized excessively, it is rare that oxygen in the first tunnel barrier layer 141 becomes twice the desired content. Therefore, as described above, in view of the fact that as the thickness of the diffusion suppression metal layer becomes thinner, the insufficient oxidation of the diffusion suppression metal layer is suppressed, the diffusion suppression metal layer may be thinner than the first tunnel barrier layer 141. preferable. Furthermore, in view of the measurement results in the above-described embodiments, it is more preferable that the thickness of the diffusion suppression metal layer is half that of the first tunnel barrier layer 141.
[Test example]

  Next, the relationship between the temperature of the substrate 11 when the barrier metal layer is oxidized and the thickness of the barrier metal layer, the temperature of the substrate 11 when the barrier metal layer is oxidized, the element resistance value, and the magnetism The relationship with the resistance ratio will be described with reference to FIGS.

  A Ta layer having a thickness of 3 nm was formed on the substrate 11, and an Mg layer having a thickness of 50 nm was formed on the Ta layer as a barrier metal layer, thereby obtaining a laminate of a plurality of test examples. And the laminated body of the test example was heated for 900 second at each temperature of 75 degreeC, 100 degreeC, 150 degreeC, and 250 degreeC by 1.33 mPa atmosphere, and the film thickness of the Mg layer after a heating was measured.

As shown in FIG. 6, when the temperature of the Mg layer was higher than 150 ° C., it was recognized that the thickness of the Mg layer rapidly decreased. This indicates that when the Mg layer is used as the barrier metal layer, the temperature of the barrier metal layer is preferably 150 ° C. or lower when the barrier metal layer is oxidized. Specifically, if the temperature of the Mg layer is 150 ° C. or lower, the evaporation of Mg is suppressed, and if the Mg layer is oxidized in an environment where the temperature of the Mg layer is 150 ° C. or lower, the first tunnel barrier layer 141 It also indicates that the time required for formation is shortened.
[Example 2]

  Next, the relationship between the temperature of the substrate when the barrier metal layer is oxidized and the element resistance value of the tunnel magnetoresistive element, and the temperature of the substrate when the barrier metal layer is oxidized and the magnetism of the tunnel magnetoresistive element. The relationship with the resistance ratio will be described with reference to FIG.

Using the tunnel magnetoresistive element manufacturing method described above, a tunnel magnetoresistive element of Example 2 having the following layer structure was obtained. At this time, the temperature of the substrate when oxidizing the barrier metal layer was changed to 75 ° C., 100 ° C., 125 ° C., and 150 ° C. Then, the element resistance value and the magnetoresistance ratio were measured for each of the four types of tunnel magnetoresistive elements having different substrate temperatures when oxidizing the barrier metal layer.
Buffer layer 12: Ta (5nm) / Cu (20nm) / Ta (5nm)
First magnetic layer 13: CoFe (2.5 nm) / Ru (0.9 nm) / CoFeB (2.5 nm)
First tunnel barrier layer 141: MgO (0.8 nm)
・ Diffusion suppression metal layer: Mg (0.4nm)
Second magnetic layer 15: CoFeB (3.0 nm)
-Capping layer 16: Ta (5nm) / Ru (12nm)

As shown in FIG. 7, it was recognized that the element resistance value of the tunnel magnetoresistive element increases as the temperature of the substrate increases when the barrier metal layer is oxidized. Further, it was recognized that the magnetoresistance ratio of the tunnel magnetoresistive element was highest when the temperature of the substrate when oxidizing the barrier metal layer was in the range of 100 ° C to 125 ° C. This indicates that the in-plane uniformity of the magnetoresistive ratio of the tunnel magnetoresistive element is ensured if the temperature in the substrate surface when oxidizing the barrier metal layer is 100 ° C. or more and 125 ° C. or less. Is. Even if the heating time is 30 to 100 seconds, the RA value can be 10 Ω · μm ² or more at which this device can substantially operate, and a significant reduction in process time is recognized. It was.
As described above, according to the first embodiment, the effects listed below can be obtained.

  (1) When a stacked body in which the tunnel barrier layer 14 is sandwiched between the first magnetic layer 13 and the second magnetic layer 15 is heated, there is a gap between the first tunnel barrier layer 141 and the second magnetic layer 15. A diffusion suppressing metal layer made of the same metal element as that constituting the first tunnel barrier layer is sandwiched.

  Therefore, even if the stacked body is heated to such an extent that oxygen diffuses from the first tunnel barrier layer 141, oxygen diffused from the first tunnel barrier layer 141 is first consumed for the oxidation of the diffusion suppression metal layer. As a result, since the oxidation of the second magnetic layer 15 can be suppressed, it is possible to suppress the tunnel magnetoresistive effect from being lowered due to the oxidation of the second magnetic layer 15.

  (2) Since the diffusion suppression metal layer is thinner than the first tunnel barrier layer 141, the diffusion suppression metal layer is the same thickness as the first tunnel barrier layer 141, or the diffusion suppression metal layer is thicker than the first tunnel barrier layer 141. Compared to the case, it is possible to suppress the non-oxidized metal element from remaining between the first tunnel barrier layer 141 and the second magnetic layer 15. Therefore, it is possible to suppress a decrease in the tunnel magnetoresistance effect due to the fact that the metal element of the diffusion suppressing metal layer is not oxidized.

  (3) A barrier metal layer is formed on the first magnetic layer 13, and then the barrier metal layer is oxidized to form the first tunnel barrier layer 141. Therefore, since the amount of metal element and the amount of oxygen change significantly on the first magnetic layer 13, compared with the case where the amount of metal element and the amount of oxygen change simultaneously, in the first tunnel barrier layer 141. The composition can be easily adjusted.

  (4) Moreover, even when the oxidation of the barrier metal layer is excessive, excess oxygen is consumed by the diffusion suppressing metal layer. Therefore, as described in the above (1), if the diffusion suppressing metal layer is formed in the first tunnel barrier layer 141, the tunnel magnetoresistive effect is reduced by the oxidation of the second magnetic layer 15. In addition to the suppression, it is also possible to increase the permissible range for the error in the degree of oxidation of the barrier metal layer.

  (5) MgO, which is a material for forming the first tunnel barrier layer 141 and the second tunnel barrier layer 142, is crystallized by the step of heating the stacked body. Therefore, it is possible to reduce the number of steps required for the tunnel magnetoresistive element manufacturing method, compared with the case where the step of crystallizing MgO and the step of heating the stacked body are carried out exceptionally. Also become.

  (6) Since the thickness of each of the first magnetic layer 13 and the second magnetic layer 15 is not less than 0.6 nm and not more than 2.5 nm, a perpendicular magnetization type tunneling magneto-resistance element can be manufactured. In addition, since the oxidation of the very thin second magnetic layer 15 is suppressed in this manner, the effect described in the above (1) becomes more remarkable.

(7) Since the third sputter chamber 26 forms both the barrier metal layer and the diffusion suppressing metal layer, the barrier metal layer and the diffusion suppressing metal layer are formed by separate vacuum chambers. In comparison, the configuration of the tunnel magnetoresistive element manufacturing apparatus can be simplified.
(Second Embodiment)

  A second embodiment of the method for manufacturing a tunnel magnetoresistive element according to the technique of the present disclosure will be described below with reference to FIGS. Note that the second embodiment is different from the first embodiment in that the oxidized barrier metal layer is heated before the diffusion suppressing metal layer is formed. Therefore, below, the difference from 1st Embodiment is mainly demonstrated and the description of the point which overlaps with 1st Embodiment is omitted.

  As shown in FIG. 5, when the amorphous MgO layer is formed as the first tunnel barrier layer 141, the controller 30 drives the oxidation chamber 28 by driving the substrate transfer robot 20R by the substrate transfer robot drive unit 20D. The substrate 11 inside is transferred to the heat treatment chamber 22. Then, the control device 30 promotes crystallization of the amorphous MgO layer by driving the heat treatment heater 22H by the heat treatment heater driving unit 22D. For example, the control device 30 holds the substrate 11 at 360 ° C. for 1 hour in an atmosphere with a magnetic field. Thereby, the first tunnel barrier layer 141 becomes a crystal having (001) orientation, and accordingly, the CoFeB alloy layer as the first magnetic layer 13 also becomes a crystal having (001) orientation.

Thereafter, as in the first embodiment, the formation of the diffusion suppressing metal layer (step S16), the formation of the second magnetic layer 15 (step S17), the formation of the capping layer 16 (step S18), and the heating process of the laminate (step) S19) is performed in this order.
As described above, according to the second embodiment, the effects listed below can be obtained in addition to the effects according to the above (1) to (7).

(8) Heat treatment for the first stacked body including the first magnetic layer 13 and the first tunnel barrier layer 141, and for the second stacked body including the first tunnel barrier layer 141, the diffusion suppression metal layer, and the second magnetic layer 15. Heat treatment is performed separately. Therefore, it is possible to set different conditions for the heat treatment performed on the first stacked body and the conditions for the heat treatment performed on the second stacked body. Therefore, it is possible to perform heat treatment according to the film thickness and composition of each layer in the first laminate, and to perform heat treatment according to the film thickness and composition of each layer in the second laminate.
In addition, the said embodiment can also be changed and implemented as follows.

  An ordered alloy material, an amorphous alloy material, or a multilayer artificial lattice material can be applied to the first magnetic layer and the second magnetic layer. For example, CoPt, FePt, CoPd, and FePd are applicable to the ordered alloy material. For example, TbFeCo and GdFeCo can be applied to the amorphous alloy material. Co—Pt, Fe—Pt, Co—Pd, and Fe—Pd are applicable to the multilayer artificial lattice material.

  In addition to the plasma oxidation method, an oxidation method using only oxygen radicals, a natural oxidation method, and a method for promoting oxidation by irradiation with ultraviolet rays can be applied to the step of oxidizing the barrier metal layer.

When a Mg layer having a thickness of, for example, 0.8 nm is used as the barrier metal layer, the Mg layer maintained at room temperature is exposed to an oxygen atmosphere of 1 Pa to 1000 Pa for 600 seconds to 1000 seconds. Such a natural oxidation method has a slower oxidation rate than the plasma oxidation method, so that the oxidation state in the barrier metal layer can be reproduced with high accuracy.
In addition, when an oxidation method using only oxygen radicals is employed, the oxidation time of about 10 seconds to 40 seconds is sufficient for the RA value to be 10 Ω · μm ² or more. Is possible.

In the step of forming the first tunnel barrier layer 141, a method of depositing an oxide of the metal element constituting the first tunnel barrier layer 141 on the substrate can be applied. The manufacturing apparatus used in such a method can simplify the apparatus configuration by omitting an oxidation chamber for oxidizing the barrier metal layer.
In this case, the first tunnel barrier layer 141 may have a desired orientation by depositing the oxide itself. With such a method, heating for crystallizing the first tunnel barrier layer 141 can be omitted.

-The method by which the process of heating a laminated body is performed other than the manufacturing apparatus of a tunnel magnetoresistive element may be sufficient. The manufacturing apparatus used for such a method can simplify the apparatus configuration by omitting the heat treatment chamber for heating the laminate.
The vacuum chamber for forming the barrier metal layer may be the first metal layer forming portion, the vacuum chamber for forming the diffusion suppressing metal layer may be the second metal layer forming portion, and these may be different vacuum chambers. With such a configuration, the formation of the barrier metal layer on one substrate and the formation of the diffusion suppressing metal layer on the other substrate can be performed at the same timing. Productivity can also be increased.

  In the second embodiment, the step of crystallizing the first tunnel barrier layer 141 may be after the diffusion suppression metal layer is formed and before the second magnetic layer 15 is formed.

  Before the second magnetic layer 15 is formed, a metal oxide that is another tunnel barrier layer different from the first tunnel barrier layer 141 and is the same as the first tunnel barrier layer 141 on the diffusion suppression metal layer A third tunnel barrier layer may be formed. That is, a third tunnel barrier layer, which is a metal oxide layer in contact with the second magnetic layer 15, may be formed between the diffusion suppression metal layer and the second magnetic layer 15. Even in such a method, the diffusion suppressing metal layer is formed on the assumption that the required thickness of the tunnel barrier layer is the same between the first magnetic layer 13 and the second magnetic layer 15. Therefore, it is possible to suppress the diffusion of oxygen to the second magnetic layer.

  T ... target, 11 ... substrate, 12 ... buffer layer, 12a, 12c, 16a ... Ta layer, 12b, 16b ... Ru layer, 13 ... first magnetic layer, 14 ... tunnel barrier layer, 15 ... second magnetic layer, 16 DESCRIPTION OF SYMBOLS ... Capping layer, 20 ... Transfer chamber, 20D ... Substrate transfer robot drive unit, 20R ... Substrate transfer robot, 21 ... Loading / unloading chamber, 21D ... Loading / unloading robot drive unit, 21R ... Loading / unloading robot, 22 ... Heat treatment chamber, 22D Heat treatment heater drive unit, 22H ... Heat treatment heater, 23 ... Cleaning chamber, 23D ... Cleaning plasma source drive unit, 23P ... Cleaning plasma source, 24 ... First sputter chamber, 24C ... First cathode, 24D ... First cathode drive Part, 25 ... second sputter chamber, 25C ... second cathode, 25D ... second cathode drive part, 26 ... first Sputter chamber, 26C ... third cathode, 26D ... third cathode drive unit, 28 ... oxidation chamber, 28D ... oxidation plasma source drive unit, 28G ... oxidation heater drive unit, 28H ... oxidation heater, 28P ... oxidation plasma source, 30 ... Control device, 30A ... control unit, 30B ... storage unit, 30C ... input / output unit, 31 ... input device, 141 ... first tunnel barrier layer, 142 ... second tunnel barrier layer.

Claims (7)

Forming a first magnetic layer on a substrate;
Forming a first tunnel barrier layer that is an oxide of a metal element on the first magnetic layer;
Forming a diffusion suppressing metal layer made of the metal element on the first tunnel barrier layer;
Forming a second magnetic layer on the diffusion suppressing metal layer;
Heating the stacked body in which the first tunnel barrier layer and the diffusion suppressing metal layer are sandwiched between the first magnetic layer and the second magnetic layer,
In the step of heating the laminate,
A method of manufacturing a tunnel magnetoresistive element, wherein a second tunnel barrier layer, which is an oxide of the metal element, is formed from the diffusion suppression metal layer by oxygen diffusing from the first tunnel barrier layer. In the step of forming the diffusion suppressing metal layer,
The method of manufacturing a tunnel magnetoresistive element according to claim 1, wherein the diffusion suppression metal layer is formed thinner than the first tunnel barrier layer. Forming the first tunnel barrier layer comprises:
Forming a barrier metal layer made of the metal element on the first magnetic layer;
The method for manufacturing a tunnel magnetoresistive element according to claim 1, further comprising oxidizing the barrier metal layer to form the first tunnel barrier layer. The metal element is magnesium;
The step of heating the laminate,
The tunnel magnetoresistive element manufacturing method according to claim 3, wherein the oxidized barrier metal layer is crystallized by heating. The step of forming the first magnetic layer includes:
Forming a CoFeB alloy layer having a thickness of 0.6 nm to 2.5 nm as the first magnetic layer;
The step of forming the second magnetic layer includes
The method of manufacturing a tunnel magnetoresistive element according to claim 4, wherein a CoFeB alloy layer having a thickness of 0.6 nm to 2.5 nm is formed as the second magnetic layer. A transport unit for transporting the substrate;
A first magnetic layer forming part for forming a first magnetic layer;
A second magnetic layer forming part for forming a second magnetic layer;
A barrier layer forming part for forming a tunnel barrier layer that is an oxide of a metal element;
A metal layer forming part for forming a diffusion suppressing metal layer made of the metal element;
A control unit for controlling the conveyance of the conveyance unit,
The laminate composed of the first magnetic layer, the second magnetic layer, the tunnel barrier layer, and the diffusion suppression metal layer is heated,
The control unit forms the stacked body by transporting the substrate in the order of the first magnetic layer forming unit, the barrier layer forming unit, the metal layer forming unit, and the second magnetic layer forming unit. Manufacturing equipment. The metal layer forming portion is a first metal layer forming portion,
The barrier layer forming part is
A second metal layer forming portion for forming a barrier metal layer made of the metal element;
A metal layer oxidation part that oxidizes the barrier metal layer,
The tunnel magnetoresistive element manufacturing apparatus according to claim 6, wherein the first metal layer forming portion and the second metal layer forming portion are the same.

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