JP2015046528A - Method of manufacturing magnetoresistive element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a magnetoresistive element which allows for highly accurate etching of the element while preventing oxidation thereof.SOLUTION: A method of manufacturing a magnetoresistive element includes a step for forming, on a substrate 11, a laminate L having a reference layer 13 including a first ferromagnetic film, a storage layer 15 including a second ferromagnetic film, and a barrier layer 14 having arranged between the first ferromagnetic film and second ferromagnetic film and composed of MgO. A mask 17M consisting of a W film is formed on the laminate L. The storage layer 15 is etched via the mask 17M, by forming a plasma of a chlorine-based gas.

Description

  The present invention relates to a method for manufacturing a magnetoresistive element utilizing the magnetoresistive effect.

  In recent years, various magnetoresistive elements using the magnetoresistive effect such as a magnetic memory (MRAM: Magnetic Random Access Memory), a magnetic head, and a magnetic sensor have been developed. In particular, in the field of magnetic memory, a spin injection type MRAM (STT (Spin-Transfer Torque) -MRAM) has been proposed in which magnetization is rewritten by spins of electrons by passing a current through an element.

A magnetoresistive element typically includes a reference layer (pinned layer) having a fixed magnetization direction, a storage layer (free layer) having a variable magnetization direction, and Al ₂ O ₃ and MgO disposed therebetween. And a barrier layer (tunnel junction layer) made of a nonmagnetic insulating material. The interface between the reference layer and the memory layer sandwiching the barrier layer is composed of a ferromagnetic film made of Fe-based material or CoFe-based material. In this type of magnetoresistive element, a reference layer, a barrier layer, and a memory layer are formed and then etched to form individual memory cells (MTJ: Magnetic Tunnel Junction).

As an etching method of a ferromagnetic film necessary for forming a memory cell, it is known to use a reactive ion etching (RIE) method. For example, Patent Document 1 describes a method of etching a ferromagnetic film with alcohol or a CO + NH ₃ carbonyl gas through a Ta mask.

JP 2005-42143 A

  The method described in Patent Document 1 has a problem that the side walls of the element are oxidized by oxygen dissociated in plasma.

  In view of the circumstances as described above, an object of the present invention is to provide a method of manufacturing a magnetoresistive element that can be etched with high accuracy while preventing oxidation of the element.

In order to achieve the above object, a method of manufacturing a magnetoresistive element according to an aspect of the present invention includes a reference layer including a first ferromagnetic film, a memory layer including a second ferromagnetic film, on a substrate, Forming a stacked body having a barrier layer made of MgO disposed between the first ferromagnetic film and the second ferromagnetic film.
A mask made of a W film is formed on the laminate.
The storage layer is etched through the mask by forming a plasma of chlorine-based gas.

It is a sectional side view showing a schematic structure of a magnetoresistive element concerning one embodiment of the present invention. It is a schematic sectional drawing which shows the structural example of each layer of the said magnetoresistive element. It is a top view which shows schematically the manufacturing apparatus of the said magnetoresistive element. It is a schematic block diagram of the etching apparatus which manufactures the said magnetoresistive element. It is a figure explaining the manufacturing method of the said magnetoresistive element, Comprising: It is a schematic sectional drawing which shows the preparation process of a laminated body. It is a figure explaining the manufacturing method of the said magnetoresistive element, Comprising: It is a schematic sectional drawing which shows the formation process of a mask pattern. It is a figure explaining the manufacturing method of the said magnetoresistive element, Comprising: It is a schematic sectional drawing which shows the etching process of an upper electrode and a memory layer. It is a figure explaining the manufacturing method of the said magnetoresistive element, Comprising: It is a schematic sectional drawing which shows the etching process of a barrier layer and a reference layer. It is a sectional side view which shows the modification of the structure of the said magnetoresistive element.

A method for manufacturing a magnetoresistive element according to an embodiment of the present invention includes a reference layer including a first ferromagnetic film, a storage layer including a second ferromagnetic film, and the first ferromagnetic film on a substrate. Forming a laminate having a barrier layer made of MgO disposed between the film and the second ferromagnetic film.
A mask made of a W film is formed on the laminate.
The storage layer is etched through the mask by forming a plasma of chlorine-based gas.

  In the magnetoresistive element manufacturing method, the second ferromagnetic film (memory layer) on the barrier layer is chemically etched by reactive ion etching (RIE) using chlorine-based gas plasma. Since oxygen is not contained in the etching gas, it is possible to prevent the storage layer from being oxidized. This makes it possible to achieve high-precision processing of the storage layer.

The chlorine-based gas is not particularly limited, and any one of Cl ₂ , BCl ₃ , SiCl ₄ or a mixed gas thereof can be used.

  The stack is not particularly limited as long as the barrier layer is sandwiched between the reference layer and the storage layer, and the reference layer may be disposed on the substrate side, or the storage layer may be on the substrate side. May be arranged.

In the step of etching the memory layer, a bias voltage may be further applied to the substrate.
Thereby, the recording layer can be accurately etched while preventing the deposition of the reaction product of the chlorine-based gas.
The method of manufacturing a magnetoresistive element further includes applying a bias voltage to the substrate to form a plasma of a mixed gas of argon and a chlorine-based gas, so that the barrier layer and the reference layer are interposed through the mask. May be etched.
By using chlorine gas as the reactive gas and argon as the sputtering gas, intermediate etching can be realized, thereby enabling the barrier layer and the reference layer to be etched with high accuracy. .

The step of etching the barrier layer may etch the barrier layer by sputter ion etching with argon ions.
Since the barrier layer made of MgO is difficult to reactively etch, sputter etching is effective. Although the etching selectivity of MgO to the W mask is not high, the consumption amount of the W mask can be kept low because the MgO film thickness is about 1 nm.

When the reference layer includes at least the first ferromagnetic film and a noble metal film, the step of etching the reference layer includes the step of etching the first ferromagnetic film by reactive ion etching using a chlorine-based gas. And a step of etching the noble metal film by sputter ion etching using argon ions.
Since the etching gas does not contain oxygen, the reference layer can be etched without oxidizing the side walls of the reference layer.

The method of manufacturing the magnetoresistive element may further include forming an electrode layer made of Ta on the stacked body. In this case, in the step of forming the mask, a W film is formed on the electrode layer, a resist mask is formed on the W film, and plasma of fluorine-based gas is formed, whereby the resist mask is formed. Then, the W film is etched.
W can be etched with a fluorine-containing gas, and Ta can be etched with a fluorine-containing gas because the etching rate is extremely slow. It becomes possible to form with high precision. Note that Ta can be etched by forming a plasma of a chlorine-based gas.
As the fluorine-based gas, for example, a single gas such as SF ₆ or CHF ₃ or a mixed gas thereof can be used.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Configuration of magnetoresistive element]
FIG. 1 is a cross-sectional view showing a schematic configuration of a magnetoresistive element according to an embodiment of the present invention. The magnetoresistive element 10 according to this embodiment includes a lower electrode 12, a reference layer (pinned layer) 13, a barrier layer (nonmagnetic insulating layer) 14, a memory layer (free layer) 15, and an upper electrode 16 on a substrate 11. It has the structure laminated | stacked in order.
For easy understanding, the structure of each layer is exaggerated, and the thickness ratio between the layers does not necessarily correspond to the actual thickness.

  The magnetoresistive element 10 constitutes an MTJ (Magnetic Tunnel Junction) having the barrier layer 14 as a tunnel junction layer, and is used as various magnetic devices such as an STT-MRAM, a magnetic head, and a magnetic sensor.

  The substrate 11 is composed of a semiconductor substrate such as a silicon (Si) substrate, but is not limited thereto, and may be a ceramic substrate or a glass substrate. The lower electrode 12 is a nonmagnetic metal single layer, multilayer, or alloy film. The reference layer 13 is composed of a ferromagnetic material layer whose magnetization direction is fixed. The barrier layer is a tunnel barrier layer that joins between the reference layer 13 and the memory layer 15 and is made of magnesium oxide (MgO). The memory layer 15 is composed of a ferromagnetic material layer whose magnetization direction can be changed. The upper electrode 16 is a metal conductor layer made of tantalum (Ta) or the like.

  The magnetoresistive element 10 can record or read information by using a change in resistance value due to a difference between the magnetization direction of the reference layer 13 and the magnetization direction of the storage layer 15. For example, the resistance value is the smallest when the magnetization directions of the layers are the same (parallel), and the resistance value is the largest when the magnetization directions of the layers are opposite (antiparallel). Therefore, by defining each data as “0” for the former magnetization mode and “1” for the latter magnetization mode, digital information can be recorded or read by the element. In the case of an STT-MRAM, information recording (writing) and reading are performed by current supply control to the storage layer 15 through the lower electrode 12 and the upper electrode 16. Here, detailed description of the principle of operation of the magnetoresistive element is omitted.

  The reference layer 13 and the memory layer 15 have a single layer structure or a laminated structure made of various materials. Examples of the material constituting each layer include iron (Fe), cobalt (Co), nickel (Ni), iridium (Ir), platinum (Pt), manganese (Mn), ruthenium (Ru), and tantalum (Ta). You can choose from. Further, these materials may contain a metalloid element such as silicon (Si), boron (B), phosphorus (P), or a rare earth element such as terbium (Tb).

  In FIG. 2, an example of the constituent material of each layer which comprises a magnetoresistive element is shown. In the present embodiment, the lower electrode 12 is composed of a Ta / Pt multilayer film. The reference layer 13 and the storage layer 15 include a CoFeB film.

The reference layer 13 and the memory layer 15 are not limited to a single layer structure of a CoFeB film, but include an MgO / CoFeB / MgO structure, a CoFeB / nonmagnetic metal (an alloy containing at least one Ta or Ta) / CoFeB / MgO structure, and others. It may be a single layer structure made of the above magnetic material or a laminated structure with other material layers. For example, Co / Pt artificial lattice, L1 ₀ ordered alloy (FePt, CoPt, FePd), L1 ₁ ordered alloy (CoPt), phase separation system alloy (CoCrPt, CoCrPt—SiO ₂ ), Heusler alloy (CoMnSi), amorphous rare earth (CoMnSi) TbFeCo) and the like.

  The interface between each of the reference layer 13 and the memory layer 15 bonded to the barrier layer 14 is composed of an Fe-based, Co-based, or CoFe-based ferromagnetic material film. In particular, in this embodiment, the interface is composed of a CoFeB film. . In the following description, the CoFeB film on the reference layer 13 side is also referred to as a first CoFeB film (first ferromagnetic layer), and the CoFeB film on the storage layer 15 side is a second CoFeB film (second ferromagnetic film). Also called.

  Magnetic memory elements such as MRAM often have a form in which a plurality of memory cells are formed on a common substrate 11. Each memory cell (the magnetoresistive element 10) is formed on the substrate 11 after a stacked body in which the lower electrode 12, the reference layer 13, the barrier layer 14, the storage layer 15, and the upper electrode 16 are stacked in order is formed on the substrate 11. The memory layer 15, the barrier layer 14, and the reference layer 13 are separately formed by sequentially etching in cell units. More specifically, as will be described later, the upper electrode 16, the memory layer 15, the barrier layer 14, and the reference layer 13 are patterned through a W (tungsten) mask formed on the upper electrode 16. .

[Magnetic resistance element manufacturing equipment]
FIG. 3 is a plan view schematically showing a magnetoresistive element manufacturing apparatus. The illustrated manufacturing apparatus 100 includes a transfer chamber 101 and a multi-chamber type having a load chamber 101, an unload chamber 102, a first etching chamber 104, a second etching chamber 105, and an ashing chamber 106 arranged around the transfer chamber 101. Consists of vacuum processing equipment.

  In the transfer chamber 101, a transfer robot for transferring the substrate to each chamber is arranged. The first etching chamber 104 and the second etching chamber 105 are each configured by an etching apparatus having the same configuration. In this embodiment, the first etching chamber 104 is configured by an etching apparatus for high-temperature etching, The second etching chamber 105 is composed of an etching apparatus for room temperature etching.

  FIG. 4 is a schematic configuration diagram of the etching apparatus. The illustrated etching apparatus 20 is configured as a magnetic field inductively coupled plasma etching apparatus, but is not limited to this.

  The etching apparatus 20 includes a chamber 21 that can be evacuated. A stage 25 that supports the substrate is installed in the chamber 21. An electrostatic chuck that holds the substrate placed on the stage 25 is disposed on the upper surface of the stage 25, and serves as a mechanism that introduces He into the back surface of the substrate after chucking to equalize the heat. The etching apparatus 20 includes a chiller circulation unit 26 that circulates the heat medium while controlling the temperature on the upper surface of the stage 25 or inside the stage 25. The chiller circulation unit 26 can maintain the stage 25 at a predetermined temperature. In the case of an etching apparatus for high temperature etching, a heater is built in the stage 25 so that the heating temperature can be controlled.

  Around the stage 25, an adhesion preventing plate 23 that partitions the plasma forming space 22 is installed. The etching apparatus 20 forms plasma of a reactive gas (etchant) introduced into the plasma forming space 22 and generates radicals of the reactive gas. The type of reactive gas is set or switched according to the type of material film to be etched. For example, a fluorine-based gas is used for patterning a W mask, a chlorine-based gas is used for patterning an upper electrode and a storage layer, and a barrier layer is used. When the reference layer is patterned, a mixed gas of argon and a chlorine-based gas can be introduced.

As the fluorine-based gas, for example, a single gas such as SF ₆ or CHF ₃ or a mixed gas thereof is used. The fluorine radicals chemically react with W to generate WF ₆ having a high vapor pressure, thereby selectively etching the W film. As the chlorine-based gas, Cl ₂ is used, but besides this, BCl ₃ , SiCl _4, etc. can be applied. Chlorine radicals chemically etch the ferromagnetic layer by chemically reacting with the ferromagnetic film to produce a high vapor pressure Co or Fe chlorine compound.

  As a plasma generation mechanism, the etching apparatus 20 includes an antenna 28, a high frequency power source 29, a magnet unit 30, a gas introduction line, and the like. The antenna 28 is disposed on the upper portion of the lid 24 that closes the upper portion of the plasma forming space 22, and is connected to a high frequency power source 29 to form a high frequency induction electric field in the plasma forming space 22. The magnet unit 30 is installed on the top of the lid 24 and forms a fixed magnetic field in the plasma forming space 22. The reactive gas introduced into the plasma forming space 22 through the gas introduction system is converted into plasma by receiving the action of the induction electric field by the antenna 28 and the action of the fixed magnetic field by the magnet unit 30. The etching apparatus 20 includes a bias power supply 27 that attracts ions in the plasma to the stage 25 side. The bias power source 27 can be composed of a high frequency power source.

  In each process from the formation of the W mask to the etching of the reference layer, a different etching apparatus may be used for each process, or each process can be continuously performed by one etching apparatus.

[Method of manufacturing magnetoresistive element]
Next, the manufacturing method of the magnetoresistive element 10 of this embodiment is demonstrated. 5 to 8 are process cross-sectional views illustrating a method for manufacturing the magnetoresistive element 10.

(Laminate production process)
As illustrated in FIG. 5, a stacked body L in which a lower electrode 12, a reference layer 13, a barrier layer 14, a memory layer 15, and an upper electrode 16 are sequentially formed on a substrate 11 is manufactured. Each layer is formed in a predetermined thickness by a thin film forming method such as sputtering or CVD.

(Mask pattern forming process)
Subsequently, an etching mask for processing the stacked body L in units of cells is formed. In this embodiment, a W film 17 is formed on the upper electrode 16 as a mask material (FIG. 5). The thickness of the W film 17 is not particularly limited, but is formed to a thickness that can function as a mask to the end in the MTJ etching process described later. In this embodiment, the W film 17 is formed with a thickness of 30 nm.

Next, a photoresist film corresponding to electron beam drawing is formed on the W film 17, and a resist pattern 19 shown in FIG. 5 is formed through electron beam drawing, development processing, and the like. The pattern size is not particularly limited, and is appropriately set according to the size of the element size. For example, the pattern size is formed to a size of 30 to 100 nmφ. Instead of the photoresist pattern, it may be composed of a SiN film, a SiO ₂ film, a laminated film of SiN and SiO ₂ or the like.

Next, as shown in FIG. 6, for example, in the second etching chamber 105, the W film 17 is etched through the resist pattern 19. As the etching gas, a mixed gas of SF ₆ and CHF ₃ is used, and WF ₆ is generated by RIE, whereby the W film 17 is etched. As described above, the W mask 17M is formed on the upper electrode 16.

  Thereafter, the resist pattern 19 is removed by an ashing process in the ashing chamber 106. The resist pattern 19 may be left on the SiN mask 18M because it is naturally removed by the subsequent etching process.

Flow ratio of SF ₆ for the CHF ₃ is not particularly limited, improved selectivity between the resist pattern 19 as SF ₆ is small, tends to be processed vertically W film as SF ₆ is large. From such a viewpoint, the flow rate ratio of SF ₆ to CHF ₃ can be, for example, 5 [at%] or more and 30 [at%] or less.

The pressure during etching can be set in the range of 0.1 Pa to 3 Pa, the antenna power is 300 W to 1000 W, and the substrate bias is in the range of 0 W to 100 W (0.32 W / cm ² ). By applying a substrate bias, deposition of the reaction product of CHF ₃ can be prevented. If the bias power is too high, the etching rate of the underlying Ta film (upper electrode 16) tends to increase. In this embodiment, the pressure is 0.3 [Pa], the antenna power is 800 [W], and the bias power is 10 [W].

  By using a fluorine-based gas as an etching gas for the W film 17, a high selection ratio can be secured with respect to the resist pattern 19 and the Ta film (upper electrode 16), and the W mask 17 can be formed with high accuracy.

  The W film 17 can also be used as an upper electrode. In this case, since the etching gas for the W film 17 does not contain oxygen, it is possible to prevent the underlying FeCoB film (memory layer 15) from being oxidized.

  Subsequently, the MTJ multilayer film below the upper electrode 16 is processed into a cell size. This step includes a first etching step for processing the upper electrode 16 and the memory layer 15 and a second etching step for processing the barrier layer 14 and the reference layer 13.

(First etching process)
As shown in FIG. 7, in the first etching process, the upper electrode 16 (Ta film) and the memory layer 15 (CoFeB film) are sequentially etched through the W mask 17M in the first etching chamber 104. In the present embodiment, the upper electrode 16 and the memory layer 15 are reactively etched by forming chlorine gas plasma.

The etching conditions are not particularly limited. For example, the substrate temperature is 180 ° C., the gas pressure is 0.5 [Pa], the antenna input power is 2000 [W], and the bias input power is 0.14 [W / cm ² ]. .

  In the first etching process, since the etching gas does not contain oxygen, oxidation of the sidewall of the memory layer 15 (FeCoB film) can be prevented. In addition, since the W mask 17M is hardly etched with a chlorine-based gas, a high etching selectivity can be ensured. Furthermore, the barrier layer 14 (MgO film) functions effectively as an etching stopper layer because it is not etched with a chlorine-based gas. Thereby, the upper electrode 16 and the memory layer 15 can be formed with high accuracy.

(Second etching process)
In the second etching step, the barrier layer 14 (MgO) and the reference layer 13 are sequentially etched through the W mask 17M in the first etching chamber 104 as shown in FIG. In the present embodiment, the barrier layer 14 (MgO) and the reference layer 13 are sequentially etched by applying a bias power to the substrate 11 and forming a plasma of a mixed gas of argon and chlorine gas.

  The reference layer 13 is composed of a multilayer film or an alloy film including a noble metal film (Pt, Pd, etc.) and a ferromagnetic film (Co, Fe, etc.), and the total thickness of each is about 10 to 20 nm. Unlike ferromagnetic films, noble metal films such as Pt and MgO films cannot be reactively etched with an etching gas such as halogen. W, like Pt and MgO, is a material that cannot be etched reactively in a chlorine system, and thus can sufficiently function as a mask. Since the barrier layer is usually as thin as about 1 nm, the selectivity with respect to the W mask 17M does not become a big problem even if it is etched by sputtering. As for the sputtering yield of Ru, Pt, Pd, and W, W is the lowest. That is, since W can secure a large selection ratio with respect to the noble metal film even by sputter etching, a fine element can be processed.

Table 1 shows the sputter yield (atoms / ion) of W, Co, Fe, Pt, Pd, and Ru when the acceleration energy of Ar ions (Ar ⁺ ) is 100 [eV], 300 [eV], and 600 [eV]. .

  Therefore, in this embodiment, intermediate etching is realized by using a chlorine-based gas as the reactive gas and argon as the sputter gas, thereby increasing the barrier layer 14 and the reference layer 13. It was possible to perform etching accurately.

  That is, the barrier layer 14 is sputter-etched (sputter ion etching) with argon ions. As for the reference layer 13, the noble metal film is sputtered by argon ions, and the ferromagnetic film is reactively etched by chlorine gas.

Etching conditions are such that the substrate temperature is 180 ° C., the argon / chlorine gas ratio is 90/10 percent, and the substrate bias is 1.0 [W / cm ² ], but of course this is not limiting.

  For example, the flow rate ratio between the argon gas and the chlorine gas is not limited to the above, and the amount of the chlorine gas with respect to the argon gas can be, for example, 5 [at%] or more and 20 [at%] or less. If the chlorine gas is less than 5 [at%], sputter ion etching with argon gas tends to be strong, and as a result, a sub-trench is induced, and high-precision etching of the reference layer 13 becomes difficult. On the other hand, if the chlorine gas exceeds 20 [at%], the abundance ratio of argon decreases, and it becomes difficult to appropriately etch the noble metal film.

The bias voltage applied to the substrate 11 can be, for example, not less than 0.5 [W / cm ² ] and not more than 2.6 [W / cm ² ]. When the bias voltage is less than 0.5 [W / cm ² ], the sputter etching action by argon ions is lowered, and it becomes difficult to appropriately etch the noble metal film. On the other hand, if the bias voltage exceeds 2.6 [W / cm ² ], the durability of the W mask 17M may be reduced.

  As described above, according to the present embodiment, the reference layer 13 can be etched with high accuracy. Thereby, a fine memory cell can be manufactured with high accuracy.

  Further, according to the present embodiment, since the etching gas not containing oxygen is used for etching the reference layer 13, the side wall of the reference layer 13 (ferromagnetic film) is prevented from being oxidized, and the desired magnetoresistance effect is obtained. The MTJ can be formed with high accuracy.

  The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

  For example, in the above embodiment, the configuration example of the magnetoresistive element has been described by taking the configuration example shown in FIG. 2 as an example. However, the present invention is not limited to this, and the MgO layer and a pair of ferromagnetic layers sandwiching the MgO layer are excluded. The configuration of the other layers can be changed as appropriate.

  In the above embodiment, an example in which the reference layer 13 is disposed closer to the substrate 11 than the storage layer 15 has been described as the configuration of the magnetoresistive element. However, the present invention is not limited to this, and the storage layer 15 as shown in FIG. May be arranged closer to the substrate 11 than the reference layer 13. The magnetoresistive element 30 shown in FIG. 10 is laminated on the substrate 11 in the order of the lower electrode 12, the memory layer 15, the barrier layer 14, the reference layer 13, and the upper electrode 16. Then, the upper electrode 16, the reference layer 13, the barrier layer 14 and the memory layer 15 are sequentially etched through the W mask 17M to form a cell. In this case, the etching conditions similar to those in the second etching step can be adopted for the etching of the reference layer 13 and the barrier layer 14, and the etching conditions similar to those in the first etching step can be adopted for the etching of the memory layer 15. Can be adopted.

  In the above embodiment, the etching process (first etching process) of the upper electrode 16 and the memory layer 15 and the etching process (second etching process) of the barrier layer 14 and the reference layer 13 are performed separately. However, instead of this, each layer may be etched in a single etching step.

In this case, a mixed gas of argon and a chlorine-based gas is used as the etching gas for the upper electrode 16 and the memory layer 15, the substrate temperature is 180 ° C., the pressure is 0.3 [Pa] to 3 [Pa], and the substrate The bias may be 0.5 [W / cm ² ] or more and 2.6 [W / cm ² ] or less. When the pressure is low, the sputterability is strong and the sub-trench tends to enter. When the pressure is high, the shape tends to be gentle. Although the mixing ratio of the chlorine-based gas depends on the antenna power and pressure, the higher the flow ratio of the chlorine-based gas, the higher the selectivity of the material that can be reactively etched, and the shape tends to be vertical. By appropriately optimizing these conditions, an intermediate condition between a material that can be reactively etched and a material that can be etched by sputtering can be selected.

  Further, in the above embodiment, the upper electrode 16 is composed of a Ta film, but it may be composed of a W film instead. In this case, the W film can be used as an etching mask for the memory layer, the barrier layer, and the reference layer.

DESCRIPTION OF SYMBOLS 10 ... Magnetoresistive element 11 ... Substrate 12 ... Lower electrode 13 ... Reference layer 14 ... Barrier layer 15 ... Memory layer 16 ... Upper electrode 17M ... W mask

Claims (7)

A reference layer including a first ferromagnetic film, a memory layer including a second ferromagnetic film, and the first ferromagnetic film and the second ferromagnetic film are disposed on the substrate. Forming a laminate having a barrier layer made of MgO,
Forming a mask made of a W film on the laminate;
A method of manufacturing a magnetoresistive element, wherein the memory layer is etched through the mask by forming plasma of a chlorine-based gas. It is a manufacturing method of the magnetoresistive element according to claim 1,
A method for manufacturing a magnetoresistive element, wherein any one of Cl ₂ , BCl ₃ , SiCl ₄ , or a mixed gas thereof is used as the chlorine-based gas. A method of manufacturing a magnetoresistive element according to claim 1 or 2,
The step of etching the storage layer further includes applying a bias voltage to the substrate. The method of manufacturing a magnetoresistive element according to any one of claims 1 to 3, further comprising:
A method of manufacturing a magnetoresistive element, wherein a bias voltage is applied to the substrate to form a plasma of a mixed gas of argon and a chlorine-based gas, thereby etching the barrier layer and the reference layer through the mask. It is a manufacturing method of the magnetoresistive element according to claim 4,
The step of etching the barrier layer comprises etching the barrier layer by sputter ion etching using argon ions. It is a manufacturing method of the magnetoresistive element according to claim 4 or 5,
The reference layer includes at least the first ferromagnetic film and a noble metal film,
Etching the reference layer comprises:
Etching the first ferromagnetic film by reactive ion etching with a chlorine-based gas;
And a step of etching the noble metal film by sputter ion etching with argon ions. A method of manufacturing a magnetoresistive element according to any one of claims 1 to 5, further comprising:
An electrode layer made of Ta is formed on the laminate,
The step of forming the mask includes
Forming a W film on the electrode layer;
Forming a resist mask on the W film;
A method of manufacturing a magnetoresistive element, wherein the W film is etched through the resist mask by forming a fluorine gas plasma.

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