JP2009158089A - Method of manufacturing spin valve type massive magnetic reluctance film or tmr film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a spin valve type massive magnetic reluctance film having both a high magnetic reluctance variation rate (MR ratio) and a low inter-layer coupling magnetic field (Hin). <P>SOLUTION: In the spin valve type massive magnetic reluctance film in which a buffer layer, an anti-ferromagnetic layer, a magnetic pinned layer, a non-magnetic transmission layer, a magnetic free layer, and a protective layer are continuously laminated on a substrate, the inter-layer coupling magnetic field operating between the magnetic pinned layer and magnetic free layer is reduced by performing plasma treatment for the prescribed lamination boundary, and a high MR ratio is obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a method for manufacturing a spin valve type giant magnetoresistive thin film or TMR film , and more particularly to a method for producing a high performance spin valve type giant magnetoresistive thin film or TMR film suitable for a magnetic reproducing head of a magnetic disk drive.

  A spin-valve giant magnetoresistive thin film used in a magnetic read head of a magnetic disk drive is a multilayer film composed of a plurality of layers (thin films) of an antiferromagnetic layer, a magnetization fixed layer, a nonmagnetic conductive layer, and a magnetization free layer. It has a structure. In the multilayer structure of the spin valve type giant magnetoresistive thin film, a nonmagnetic conductive layer is provided between the magnetization fixed layer and the magnetization free layer, and is separated by the nonmagnetic conductive layer. In addition, since the antiferromagnetic layer is adjacent to the magnetization fixed layer, the magnetic moment of the magnetization fixed layer is fixed in one direction by exchange coupling with the antiferromagnetic layer. On the other hand, the magnetic moment of the magnetization free layer is freely rotated according to the external magnetic field.

  In the spin valve type giant magnetoresistive thin film, a so-called giant magnetoresistive effect is obtained in which the electrical resistance changes depending on the relative angle formed by the magnetic moment of the magnetization fixed layer and the magnetic moment of the magnetization free layer. The rate of change in electrical resistance due to the giant magnetoresistance effect is called magnetoresistance change rate (MR ratio), and the MR ratio of the spin valve type giant magnetoresistive thin film is much higher than that of the conventional anisotropic magnetoresistive thin film. It has the characteristic.

  There are three types of spin valve type giant magnetoresistive thin films. In the first type, as shown in FIG. 17, the buffer layer 112, the antiferromagnetic layer 113, the magnetization fixed layer 114, the nonmagnetic conductive layer 115, the magnetization free layer 116, and the protective layer 117 are sequentially arranged from the substrate 111 side. It is a so-called bottom type that is laminated. In the second type, as shown in FIG. 18, the buffer layer 112, the magnetization free layer 116, the nonmagnetic conductive layer 115, the magnetization fixed layer 114, the antiferromagnetic layer 113, and the protective layer 117 are sequentially arranged from the substrate 111 side. It is a so-called top type that is laminated. As shown in FIG. 19, the third type includes a buffer layer 112, a first antiferromagnetic layer 113A, a first magnetization fixed layer 114A, a first nonmagnetic conductive layer 115A, a magnetization free layer 116, a first layer from the substrate 111 side. 2 is a so-called dual type in which a nonmagnetic conductive layer 115B, a second magnetization fixed layer 114B, a second antiferromagnetic layer 113B, and a protective layer 117 are successively stacked.

  In the above-described three types of spin-valve giant magnetoresistive thin films, the magnetic pinned layers 114, 114A, 114B, which have conventionally been a single layer, are further laminated to a laminated ferrimagnetic layer element including a magnetic pinned layer element, a nonmagnetic layer, and a magnetic pinned layer element. A thin film replaced with a structure has also been proposed (US Pat. No. 5,465,185). Further, the magnetization free layer 116 may be a single layer structure or a multilayer structure. In the multilayer structure of the magnetization free layer and the magnetization fixed layer, all are magnetic films, but different magnetic films may be laminated or a sandwich structure with a nonmagnetic film sandwiched therebetween may be formed.

  The giant magnetoresistive effect of the spin valve giant magnetoresistive thin film is caused by spin-dependent scattering at the laminated interface of the laminated film. Therefore, in order to obtain a high MR ratio, the cleanliness and flatness of the interface are important in the manufacturing process of the spin valve film. Therefore, in the spin valve type giant magnetoresistive thin film, in order to achieve cleanliness and flatness of the interface, the same vacuum chamber is used so that the deposition interval between layers is as short as possible continuously in a high vacuum. Often formed into a film.

  Examples of film forming methods in vacuum include magnetron sputtering, ion beam sputtering, ECR sputtering, counter target sputtering, high frequency sputtering, electron beam evaporation, resistance heating evaporation, MBE (Molecular Beam Epitaxy), and the like.

  In order to obtain a high MR ratio, the nonmagnetic conductive layer 115 should be thin in order to suppress the flow of conduction electrons (shunt effect) that does not contribute to the giant magnetoresistance effect. However, if the film thickness of the nonmagnetic conductive layer 115 is reduced, the magnetization fixed layer 114 and the magnetization free layer 116 are ferromagnetically coupled via the nonmagnetic conductive layer 115. The interlayer coupling magnetic field (Hin) between the magnetization fixed layer and the magnetization free layer is preferably small for practical use of the magnetic read head of the magnetic disk drive device, and a magnetic field having a value within the range of −10 to +10 Oe is desirable. . Conventionally, in order to reduce the interlayer coupling magnetic field, the film thickness of the nonmagnetic conductive layer 115 has been set to 2.5 to 3.5 nm.

  In the conventional technique, a ferromagnetic oxide generated between the magnetization fixed layer and the magnetization free layer by inserting an extremely thin oxide layer (NOL: Nano oxide layer) of 1 nm or less into the magnetization fixed layer in the bottom type spin valve film. Techniques for reducing binding have also been proposed (Y. Kamiguchi et al .: Digests of INTERMAG '99, DB-01). As a result, a relatively small interlayer coupling magnetic field is obtained even where the nonmagnetic conductive layer is thin (2 to 2.5 nm), and a high MR ratio is obtained.

  In the conventional spin-valve type giant magnetoresistive thin film, the thickness of the nonmagnetic conductive layer is set to be thick (2.5 to 3.5 nm) in order to reduce the interlayer coupling magnetic field, but this does not contribute to the giant magnetoresistive effect. There is a problem that a flow of conduction electrons (shunt effect) occurs and the MR ratio is lowered. Furthermore, in the manufacturing process of the above-mentioned extremely thin oxide layer, an oxidation process is required during the formation of the magnetization fixed layer. The oxidation process is complicated and reproducibility is difficult to obtain.

An object of the present invention is to solve the above-described problem. Even when the nonmagnetic conductive layer is thin, a high MR ratio can be obtained by keeping the interlayer coupling magnetic field low without using an oxidation process. An object of the present invention is to provide a method for producing a spin valve type giant magnetoresistive thin film or TMR film .

The spin valve type giant magnetoresistive thin film or TMR film manufacturing method according to the present invention is configured as follows to achieve the above object.

In a first manufacturing method (corresponding to claim 1), a buffer layer deposited on a substrate, a nonmagnetic conductive layer or an oxide layer , a magnetization fixed layer and a magnetization free layer sandwiching the buffer layer, and the magnetization fixed layer are adjacent to each other. in antiferromagnetic layer and a multilayer portion comprising a method of manufacturing a spin-valve giant magnetoresistive thin film or a TMR film consisting of a protective layer deposited on top formed,
Wherein the at least one position of the plurality of interfaces formed between the nonmagnetic conductive layer or the oxide layer and the buffer layer,
In this method, the inert gas plasma treatment is performed under the condition that the substrate bias voltage (Vdc) is lower than 0V and is in the range of −300V or higher . In this spin valve type giant magnetoresistive thin film or TMR film manufacturing method, the plurality of interfaces formed below the nonmagnetic conductive layer are appropriately subjected to plasma treatment to improve the flatness and cleanliness of each layer, This enables a high MR ratio and a low Hin.

The second production method (corresponding to Claim 2), in the first manufacturing method described above, preferably, the magnetization fixed layer in the multilayer portion is formed on the substrate side and the magnetization free layer is the protective layer formed on the side, and the magnetization fixed layer and / or the magnetization free layer is made of a single layer or multiple layers, wherein the plurality of interfaces formed between the nonmagnetic conductive layer or the oxide layer and the buffer layer The plasma treatment is performed on at least one of them. This method is a manufacturing method of a bottom type spin valve type giant magnetoresistive thin film or TMR film .

Third manufacturing method (corresponding to claim 3), in the first manufacturing method described above, preferably, the magnetization free layer in the multilayer portion is formed on the substrate side and the magnetization fixed layer is the protective layer formed on the side, and the magnetization fixed layer and / or the magnetization free layer is made of a single layer or plural layers, a plurality of interfaces formed between the nonmagnetic conductive layer or the oxide layer and the buffer layer, and and performing the plasma treatment in at least one position of the plurality of interfaces of the magnetization fixed layer. This method is a method of manufacturing a top type spin valve type giant magnetoresistive thin film or TMR film .

In the fourth manufacturing method (corresponding to claim 4 ), a buffer layer, an antiferromagnetic layer, a magnetization fixed layer, a nonmagnetic conductive layer or oxide layer , a magnetization free layer, and a protective layer are successively formed on the substrate. In the manufacturing method of the bottom type spin valve type giant magnetoresistive thin film or TMR film to be laminated,
At least one of the plurality of interfaces formed between the nonmagnetic conductive layer or the oxide layer and the buffer layer ,
In this method, the inert gas plasma treatment is performed under the condition that the substrate bias voltage (Vdc) is lower than 0V and is in the range of −300V or higher .

The fifth method of manufacturing (corresponding to claim 5), in the fourth method described above, preferably, the magnetization fixed layer, the first magnetization pinned layer element and the second magnetization fixing layer separated by a nonmagnetic layer A laminated ferrimagnetic pinned layer having a three-layer structure of elements;
The antiferromagnetic layer and the interface of the first magnetization pinning layer element, the interface of the first magnetization pinned layer element and the non-magnetic layer, the interface between the nonmagnetic layer and the second magnetization pinned layer element, the second magnetization and wherein said plasma treatment be performed at at least one portion in the interface of the pinned layer element nonmagnetic conductive layer or the oxide layer.

In the sixth manufacturing method (corresponding to claim 6 ), a buffer layer, a magnetization free layer, a nonmagnetic conductive layer or oxide layer, a magnetization fixed layer, an antiferromagnetic layer, and a protective layer are successively formed on the substrate. In the manufacturing method of the laminated top type spin valve type giant magnetoresistive thin film or TMR film ,
At least one of the plurality of interfaces formed between the nonmagnetic conductive layer or the oxide layer and the buffer layer ,
In this method, the inert gas plasma treatment is performed under the condition that the substrate bias voltage (Vdc) is lower than 0V and is in the range of −300V or higher .

Seventh production method (corresponding to Claim 7), in the sixth method described above, preferably, the magnetization fixed layer, the first magnetization pinned layer element and the second magnetization fixing layer separated by a nonmagnetic layer A laminated ferrimagnetic pinned layer having a three-layer structure of elements;
Interface of the first magnetization pinning layer element and the non-magnetic layer, and performing the plasma treatment in at least one location of the interface of the nonmagnetic layer and the second magnetization pinning layer element.

The eighth manufacturing method (corresponding to claim 8 ) is to provide a buffer layer, a first antiferromagnetic layer, a first magnetization fixed layer, a first nonmagnetic conductive layer or a first oxide layer , a magnetization free layer on a substrate, Dual type spin-valve giant magnetoresistive thin film or TMR film sequentially laminated in the order of the second nonmagnetic conductive layer or second oxide layer , second magnetization fixed layer, second antiferromagnetic layer, protective layer In the manufacturing method of
At least one of the plurality of interfaces formed between the nonmagnetic conductive layer or the oxide layer and the buffer layer ,
In this method, the inert gas plasma treatment is performed under the condition that the substrate bias voltage (Vdc) is lower than 0V and is in the range of −300V or higher .

Ninth production method of (corresponding to claim 9) is the method of the eighth, preferably, the first magnetization pinned layer first magnetization fixed layer element, the first nonmagnetic layer, the second magnetization pinned layer element A first laminated ferrimagnetic structure having a three-layer structure, wherein the second magnetization fixed layer has a three-layer structure of a third magnetization fixed layer element, a second nonmagnetic layer, and a fourth magnetization fixed layer element. And
Interface wherein the first antiferromagnetic layer first magnetization fixed layer element, of the first magnetization pinning layer element and the first non-magnetic layer interface, and the first non-magnetic layer of the second magnetization pinning layer element interface, an interface between the second magnetization pinning layer element and the first non-magnetic conducting layer or said first oxide layer, the interface between the third magnetization fixed layer element and the second non-magnetic layer, said second non-magnetic and performing the plasma treatment in at least one location of the interface of the the layer fourth magnetization fixed layer element.

In the tenth manufacturing method (corresponding to claim 10 ), in each of the manufacturing methods described above, preferably, the buffer layer is a multilayer film composed of two or more layers, and a plurality of the buffer layers are present in the buffer layer. and performing the plasma treatment in at least one location of the interface.

An eleventh manufacturing method (corresponding to claim 11 ) is preferably characterized in that, in each of the manufacturing methods described above, the substrate bias voltage is in a range smaller than 0V and higher than −30V .

In a twelfth manufacturing method (corresponding to claim 12 ), in the eleventh manufacturing method, preferably, the substrate bias voltage is smaller than 0 V and in a range of −15 V or more .

In a thirteenth manufacturing method (corresponding to claim 13 ), in each of the above manufacturing methods, preferably, the plasma treatment uses plasma using a high frequency in an inert gas atmosphere of 0.01 to 100 Pa. It is characterized by .
In a fourteenth manufacturing method (corresponding to claim 14), in each of the above methods, the plasma treatment is performed by applying a high-frequency power of 0.5 W / cm ² or less per unit area to an electrode on which a substrate is disposed. And generating the substrate bias voltage.
A fifteenth manufacturing method (corresponding to claim 15) is characterized in that, in each of the above methods, the processing time of the plasma processing is a time not exceeding 1 minute.

  In the method of manufacturing a spin valve type giant magnetoresistive thin film or TMR film according to the present invention, the film formation is temporarily interrupted during the film formation of the spin valve film or TMR film having a multilayer structure, and the interface is subjected to ion bombardment treatment, preferably plasma treatment. And then the film formation is resumed. In this manufacturing method, the plasma treatment is not necessarily performed in the film forming chamber, and may be performed by moving to another vacuum chamber via an adjacent vacuum chamber or a vacuum transfer chamber.

  In the manufacturing method according to the present invention, a Cu layer is used for the nonmagnetic conductive layer regardless of the structure of the spin valve film such as bottom type, top type, dual spin valve or TMR film, and the film thickness of the Cu layer is 2. When the thickness is set to 1 nm, the bottom type, the top type, and the dual spin valve are designed so that the interlayer coupling magnetic field (Hin) between the magnetization fixed layer and the magnetization free layer via the Cu layer is the smallest and the MR ratio is the largest. In accordance with the spin valve film or TMR film structure, an interface for performing plasma processing or the like is appropriately selected. The interruption of the film formation by the plasma treatment is not necessarily limited to once, and may be performed a plurality of times as necessary.

  Furthermore, in the manufacturing method according to the present invention, the plasma processing conditions (RF power, processing time, pressure of Ar, etc.) are changed depending on the material used for the layer subjected to the plasma processing so that the Hin is small and the MR ratio is large. ing. Furthermore, the production method according to the present invention is characterized in that no process using oxygen or oxidation process is used.

  As apparent from the above description, according to the present invention, the film formation is temporarily interrupted in the middle of the film formation of the spin valve type giant magnetoresistive thin film and the predetermined interface is subjected to the plasma treatment or the like. The ferromagnetic magnetic coupling between the magnetization pinned layer and the magnetization free layer that sandwich the layer can be reduced, and even when the nonmagnetic conductive layer is thin, the interlayer coupling between the magnetization pinned layer and the magnetization free layer A high MR ratio can be obtained by maintaining the magnetic field (Hin) within the range of −10 to +10 Oe. Further, according to the present invention, since no process using oxygen or oxidation process is used, a high MR ratio can be obtained stably with good reproducibility.

It is a top view of the film-forming apparatus which enforces the manufacturing method of the spin valve type giant magnetoresistive thin film which concerns on this invention. It is a longitudinal cross-sectional view which shows the internal structure of the plasma processing chamber of the film-forming apparatus. It is a figure which shows the laminated structure of the bottom type spin-valve type giant magnetoresistive thin film which is an example of a multilayer film. It is a figure which shows the laminated structure of the top type spin valve type giant magnetoresistive thin film which is an example of a multilayer film. It is a figure which shows the laminated structure of the dual type spin valve type giant magnetoresistive thin film which is an example of a multilayer film. FIG. 5 is a characteristic diagram showing the dependency of the interface for plasma processing in the bottom type spin valve type giant magnetoresistive thin film according to the first embodiment of the present invention. FIG. 10 is a characteristic diagram showing the dependency of the interface for plasma processing in a top type spin valve giant magnetoresistive thin film according to the second embodiment of the present invention. FIG. 9 is a characteristic diagram showing the dependency of the Ru / CoFe interface on the plasma processing time in a bottom type spin-valve giant magnetoresistive thin film according to the third embodiment of the present invention. It is a characteristic view which shows 4th Example of this invention and shows the interface dependence of a dual type spin valve type giant magnetoresistive thin film. FIG. 10 is a characteristic diagram showing the dependency of the CoFe / Cu interface on the plasma processing time in a bottom type spin-valve giant magnetoresistive thin film according to a fifth embodiment of the present invention. FIG. 10 is a characteristic diagram showing a comparison of MR curves in the case of a standard type of a bottom type spin-valve type giant magnetoresistive thin film, NOL, and with plasma treatment according to a sixth embodiment of the present invention. 7 shows a seventh embodiment of the present invention, in the case of no plasma treatment in a bottom type spin-valve giant magnetoresistive thin film, when NOL is inserted, when a Ru / CoFe interface is plasma treated, and a Ru / CoFe interface FIG. 5 is a characteristic diagram showing the dependency of the MR ratio on the Cu layer thickness when the CoFe / Cu interface is plasma treated. 7 shows a seventh embodiment of the present invention, in the case of no plasma treatment in a bottom type spin-valve giant magnetoresistive thin film, when NOL is inserted, when a Ru / CoFe interface is plasma treated, and a Ru / CoFe interface It is a characteristic view which shows the Cu layer thickness dependence of Hin at the time of plasma-processing the CoFe / Cu interface. The characteristic diagram which shows 8th Example of this invention, and shows the MR curve major loop when the Ru / CoFe interface is plasma-treated in the bottom type spin-valve giant magnetoresistive thin film and when the CoFe / Cu interface is plasma-treated It is. FIG. 10 is a characteristic diagram showing an MR curve minor loop when the Ru / CoFe interface is plasma-treated and the CoFe / Cu interface is plasma-treated in the bottom type spin-valve giant magnetoresistive thin film according to the eighth embodiment of the present invention. It is. The characteristic view which shows the 9th Example of this invention and shows the dependence of the bias voltage Vdc to the board | substrate which is a plasma condition in the plasma processing of the Ru / CoFe interface in the manufacturing method of a bottom type spin-valve type giant magnetoresistive thin film It is. It is sectional drawing which shows an example of the laminated structure of a bottom type spin-valve type giant magnetoresistive thin film. It is sectional drawing which shows an example of the laminated structure of a top type spin valve type giant magnetoresistive thin film. It is sectional drawing which shows an example of the laminated structure of a dual type spin-valve type giant magnetoresistive thin film.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows a configuration diagram of a film forming apparatus used for carrying out a method of manufacturing a spin valve type giant magnetoresistive thin film according to the present invention. The film forming apparatus 10 is a multi-chamber type film forming apparatus. The film forming apparatus 10 includes a vacuum transfer chamber 12 in which a substrate transfer robot 11 is provided, a film forming chamber 13A, a film forming chamber 13B, a plasma processing chamber 14 and a load lock chamber 15 coupled to the vacuum transfer chamber 12. Consists of The film forming chambers 13A and 13B are sputtering film forming chambers each provided with various types of cathodes. The movement of the substrate among the film forming chamber 13A, the film forming chamber 13B, the plasma processing chamber 14, and the load lock chamber 15 is performed by the substrate transfer robot 11 provided in the vacuum transfer chamber 12. Gate valves 16 are provided between the film forming chamber 13A, the film forming chamber 13B, the plasma processing chamber 14, and the load lock chamber 15, respectively.

  The internal structure of the plasma processing chamber 14 is shown in FIG. The plasma processing chamber 14 is formed of a vacuum chamber 21, and an upper electrode 22 and a lower electrode 23 are provided in the vacuum chamber 21. The upper electrode 22 is grounded, and the lower electrode 23 is connected to an RF power source (high frequency power source) 25 via a matching box 24. A substrate 25 is mounted on the lower electrode 23. Plasma 26 is generated between the upper electrode 22 and the lower electrode 23 in a state where the plasma generation condition is satisfied.

As a typical example of the processing operation of the plasma processing chamber 14, 0.075 Pa Ar gas is introduced into the vacuum chamber 21, and RF of 15 W (0.029 W / cm ² per unit area) is applied to the lower electrode 23. The plasma 26 is generated by applying power, and the plasma treatment is performed under the condition that the substrate bias voltage (Vdc) is smaller than 0V and is in the range of −300V or higher. The upper limit value of the substrate bias voltage is preferably −2 to −3 V, and the most preferable voltage is a voltage included in a range from −15 V to the upper limit value of the substrate bias voltage. This voltage is a voltage capable of generating plasma. As a process gas introduced into the vacuum chamber 21, an inert gas such as Kr, Xe, Ne or the like or a gas similar thereto can be used instead of Ar. The pressure of the process gas in the plasma processing chamber 14 is set to a low pressure in the range of 0.01 to 100 Pa.

  Four types of targets 31 are installed in the film forming chamber 13A, and the materials thereof are PtMn, CoFe, and NiFe. Also, four types of targets 32 are installed in the film forming chamber 13B, and the materials thereof are Cu, Ta, and Ru. The substrate 25 is moved between the film forming chambers 13A and 13B and the plasma processing chamber 14 by the substrate transfer robot 11, and a multilayer film having a desired laminated structure is formed.

  As an example, FIG. 3 shows a laminated structure of a bottom type spin valve type giant magnetoresistive thin film. According to this laminated structure, Ta (3 nm) / NiFe (2 nm) / PtMn (12 nm) / CoFe (1.8 nm) / Ru (0.8 nm) / CoFe (2.8 nm) / Cu (2 .2 nm) / CoFe (1.5 nm) / NiFe (2.5 nm) / Cu (1 nm) / Ta (3 nm) in this order. The numerical value described in parentheses in each layer is the thickness of the layer, and the unit is “nm (nanometer)”. In the above laminated structure, Ta (3 nm) and NiFe (2 nm) are the buffer layer 41, PtMn (12 nm) is the antiferromagnetic layer 42, CoFe (1.8 nm), Ru (0.8 nm) and CoFe (2.8 nm). Is a magnetization fixed layer (laminated ferrimagnetic layer) 43, Cu (2.2 nm) is a nonmagnetic conductive layer 44, CoFe (1.5 nm) and NiFe (2.5 nm) are magnetization free layers 45, and Cu (1 nm) is a spin filter 46. , Ta (3 nm) is the protective layer 47. In order to form the bottom type spin valve film as described above, first, Ta (3 nm) is formed in the film formation chamber 13B, and then NiFe (2 nm) / PtMn (12 nm) / CoFe in the film formation chamber 13A. (1.8 nm) is deposited, then Ru (0.8 nm) is deposited in the deposition chamber 13B, then CoFe (2.8 nm) is deposited in the deposition chamber 13A, and then deposited. Cu (2.2 nm) is deposited in the chamber 13B, then CoFe (1.5 nm) / NiFe (2.5 nm) is deposited in the deposition chamber 13A, and finally Cu (1 nm) is deposited in the deposition chamber 13B. / Ta (3 nm) is formed.

  Plasma treatment is appropriately performed in the film formation process of the bottom type spin valve type giant magnetoresistive thin film. When plasma processing is performed, film formation is temporarily interrupted at a desired interface, the substrate 25 is transferred to the plasma processing chamber 14, and plasma processing is executed.

  In the step of forming the bottom type spin valve film, for example, when the Ru (0.8 nm) / CoFe (2.8 nm) interface is subjected to plasma treatment, the process is as follows. First, Ta (3 nm) is deposited in the deposition chamber 13B, then NiFe (2 nm) / PtMn (12 nm) / CoFe (1.8 nm) is deposited in the deposition chamber 13A, and then the deposition chamber 13B. After depositing Ru (0.8 nm), the film is transferred to the plasma processing chamber 25 and subjected to plasma processing based on the above-described processing conditions, and then CoFe (2.8 nm) is formed in the deposition chamber 13A. Next, Cu (2.2 nm) is deposited in the deposition chamber 13B, then CoFe (1.5 nm) / NiFe (2.5 nm) is deposited in the deposition chamber 13A, and finally, the deposition chamber 13B. Then, Cu (1 nm) / Ta (3 nm) is formed.

  In the description of the above embodiment, plasma processing is performed as an example of processing a predetermined interface. However, this plasma processing is a broad concept, and the interface is processed by ion bombardment with an inert gas, or neutral. Includes treatment with particles, radicals, atoms, and other particles. The same effect can be obtained by replacing with ion beam etching using an ion gun.

  Next, an embodiment of a method for manufacturing a spin valve type giant magnetoresistive thin film according to the present invention will be described in detail with reference to FIGS. In the description of this embodiment, the plasma treated interface is revealed.

(Example 1):
Example 1 relates to a method of manufacturing the bottom type spin-valve giant magnetoresistive thin film shown in FIG. That is, Ta (3 nm) / NiFe (2 nm) / PtMn (12 nm) / CoFe (1.8 nm) / Ru (0.8 nm) / CoFe (2.8 nm) / Cu (2.2 nm) / CoFe from the substrate 25 side. This is an example in which plasma treatment is performed in the middle of film formation by a manufacturing method of a bottom type spin valve film having a laminated structure of (1.5 nm) / NiFe (2.5 nm) / Cu (1 nm) / Ta (3 nm). In FIG. 6, when the horizontal axis is “no plasma treatment”, plasma treatment is performed at each of “PtMn / CoFe interface”, “CoFe / Ru interface”, “Ru / CoFe interface”, and “CoFe / Cu interface”. In this case, the vertical axis represents MR ratio and Hin, and a characteristic diagram showing changes in MR ratio and Hin is shown. In this example, the plasma treatment time was unified to 15 seconds, and the plasma treatment interface was changed. As a result, the plasma treatment at the PtMn / CoFe interface, CoFe / Ru interface, Ru / CoFe interface, and CoFe / Cu interface reduced Hin. Was able to be realized. At the same time, the MR ratio was improved by plasma treatment at the Ru / CoFe interface and the CoFe / Cu interface. Therefore, in the film configuration of this example, it is preferable to plasma-treat the Ru / CoFe interface or the CoFe / Cu interface, and more preferably to plasma-treat both the Ru / CoFe interface and the CoFe / Cu interface.

  Ta (3 nm) / NiFe (2 nm) / PtMn (12 nm) / CoFe (1.8 nm) / Ru (0.8 nm) / CoFe (2.8 nm) / Cu (2.2 nm) / CoFe (1.5 nm) / In the bottom type spin valve film having a laminated structure of NiFe (2.5 nm) / Cu (1 nm) / Ta (3 nm), the interface of NiFe (2 nm) / PtMn (12 nm), PtMn (12 nm) / CoFe (1.8 nm) ) Interface, CoFe (1.8 nm) / Ru (0.8 nm) interface, Ru (0.8 nm) / CoFe (2.8 nm) interface, CoFe (2.8 nm) / Cu (2.2 nm) By performing plasma treatment at the interface, reduction of Hin and improvement of MR ratio are expected. In FIG. 3, the interface pointed by a right-pointing arrow is an interface that is preferably subjected to plasma treatment.

(Example 2):
Example 2 relates to a method of manufacturing the top-type spin-valve giant magnetoresistive thin film shown in FIG. That is, Ta (3 nm) / NiFe (2.5 nm) / CoFe (1.5 nm) / Cu (2.2 nm) / CoFe (2.8 nm) / Ru (0.8 nm) / CoFe (1. 8 nm) / PtMn (12 nm) / Ta (3 nm) This is an example in which plasma treatment is performed in the middle of film formation by a manufacturing method of a top type spin valve film having a laminated structure. In this laminated structure, Ta (3 nm) is a buffer layer 41, NiFe (2.5 nm) / CoFe (1.5 nm) is a magnetization free layer 45, Cu (2.2 nm) is a nonmagnetic conductive layer 44, CoFe (2. 8 nm) / Ru (0.8 nm) / CoFe (1.8 nm) is a magnetization fixed layer (laminated ferrimagnetic layer) 43, PtMn (12 nm) is an antiferromagnetic layer 42, and Ta (3 nm) is a protective layer 47. In FIG. 7, when the horizontal axis is “no plasma treatment”, plasma treatment is performed at each of “Ta / NiFe interface”, “CoFe / Ru interface”, “Cu / CoFe interface”, and “Ru / CoFe interface”. In this case, the vertical axis represents MR ratio and Hin, and a characteristic diagram showing changes in MR ratio and Hin is shown. In this embodiment, the plasma treatment time is unified to 15 seconds and the plasma treatment interface is changed. As shown in FIG. 7, the reduction of Hin can be realized by the plasma treatment of the Ta / NiFe interface and the CoFe / Cu interface. It was. In addition, the MR ratio was improved by the plasma treatment at the Ru / CoFe interface. Therefore, in the film configuration of this example, it is preferable to perform plasma treatment on at least one of the Ta / NiFe interface, the CoFe / Cu interface, and the Ru / CoFe interface, and plasma treatment is performed on both the CoFe / Cu interface and the Ru / CoFe interface. More preferably. The same effect can be expected even if the CoFe / Ru interface is plasma treated. In FIG. 4, the interface pointed by a right-pointing arrow is an interface that is preferably subjected to plasma treatment.

(Example 3):
In Example 3, an example will be described in which the plasma processing time in the method of manufacturing the bottom type spin valve giant magnetoresistive thin film shown in FIG. 3 is changed. FIG. 8 is a characteristic diagram showing changes in MR ratio and Hin when the horizontal axis is the plasma processing time (seconds; sec) and the vertical axis is the MR ratio and Hin. According to FIG. 8, in the bottom type spin valve film, when the plasma processing time at the Ru / CoFe interface is changed, the plasma processing time at the Ru / CoFe interface is in the range of 10 to 30 seconds at which the highest MR ratio can be obtained. It can be seen that the time contained in is preferred.

(Example 4):
Example 4 relates to a method of manufacturing the dual type spin valve giant magnetoresistive thin film shown in FIG. That is, from the substrate 25 side, Ta (3 nm) / NiFe (2 nm) / PtMn (12 nm) / CoFe (1.8 nm) / Ru (0.8 nm) / CoFe (2.8 nm) / Cu (2.2 nm) / CoFe (0.5 nm) / NiFe (3 nm) / CoFe (0.5 nm) / Cu (2.2 nm) / CoFe (2.8 nm) / Ru (0.8 nm) / CoFe (1.8 nm) / PtMn (12 nm) This is an example in which plasma processing is performed in the middle of film formation by a manufacturing method of a dual type spin valve film having a stacked structure of / Ta (3 nm). In this laminated structure, Ta (3 nm) / NiFe (2 nm) is the buffer layer 41, PtMn (12 nm) is the first antiferromagnetic layer 42A, CoFe (1.8 nm) / Ru (0.8 nm) / CoFe (2. 8 nm) is the first magnetization fixed layer (first laminated ferri) 43A, Cu (2.2 nm) is the first nonmagnetic conductive layer 44A, CoFe (0.5 nm) / NiFe (3 nm) / CoFe (0.5 nm) is The magnetization free layer 45, Cu (2.2 nm) is the second nonmagnetic conductive layer 44B, and CoFe (2.8 nm) / Ru (0.8 nm) / CoFe (1.8 nm) is the second magnetization fixed layer (second stacked layer). Ferri) 43B, PtMn (12 nm) is the second antiferromagnetic layer 42B, and Ta (3 nm) is the protective layer 47. In FIG. 9, the horizontal axis indicates the “Ru / CoFe interface”, “Ru / CoFe interface and Cu / CoFe interface”, and “Ru / CoFe interface and Cu / CoFe interface and Ru / CoFe interface”. In this case, the vertical axis represents MR ratio and Hin, and a characteristic diagram showing changes in MR ratio and Hin is shown. In this embodiment, when the plasma processing time is unified to 15 seconds and the plasma processing interface is changed, the reduction of Hin occurs when three interfaces of Ru / CoFe interface, Cu / CoFe interface and Ru / CoFe interface are plasma processed. And improved MR ratio. For this reason, in the film configuration of the present embodiment, it is preferable to perform plasma treatment on any of the three interfaces of the Ru / CoFe interface, the Cu / CoFe interface, and the Ru / CoFe interface. However, in order to further reduce the Hin and improve the MR ratio. It is preferable to plasma-treat all three interfaces of the Ru / CoFe interface, the CoFe / Cu interface, and the Ru / CoFe interface. In FIG. 5, the interface pointed by a right-pointing arrow is an interface on which plasma treatment is desirable.

(Example 5):
In Example 5, an example will be described in which the plasma processing time is changed in the method of manufacturing the bottom type spin valve giant magnetoresistive thin film shown in FIG. FIG. 10 is a characteristic diagram showing changes in MR ratio and Hin when the horizontal axis is the plasma processing time (seconds; sec) and the vertical axis is the MR ratio and Hin. FIG. 10 shows an example in which the plasma processing time at the Ru / CoFe interface is unified to 15 seconds and the plasma processing time at the CoFe / Cu interface is changed in the bottom type spin valve film. According to this example, it is understood that the plasma processing time at the CoFe / Cu interface is preferably 30 seconds at which the lowest Hin is obtained.

(Example 6):
In Example 6, in the production of the laminated structure of the bottom-type spin-valve giant magnetoresistive thin film shown in FIG. 3, no plasma treatment was performed, and Ru (0.8 nm) and CoFe (2.8 nm) were used. MR curve of a spin valve film when a CoFe oxide layer (NOL) having a thickness of 1 nm or less is sandwiched between and a Ru (0.8 nm) / CoFe (2.8 nm) interface is plasma-treated for 15 seconds. A comparison of is shown. In FIG. 11, the horizontal axis indicates the magnetic field strength, the vertical axis indicates the MR ratio, and NOL is set between the MR curve 51 when no plasma treatment is performed and between Ru (0.8 nm) and CoFe (2.8 nm). An MR curve 52 when sandwiched and an MR curve 53 when a Ru (0.8 nm) / CoFe (2.8 nm) interface is plasma-treated for 15 seconds are shown. According to FIG. 11, the MR ratio was improved from 7.9% to 10.4% by inserting NOL in the same film structure, and 11.2% was obtained when the plasma treatment was further performed. A similar effect can be obtained by forming a CoFe layer having a thickness of 1 to 4 nm after the insertion of NOL and then performing plasma treatment. The coercive force (Hc) of the magnetization free layer composed of CoFe (1.5 nm) / NiFe (2.5 nm) of the spin valve film without plasma treatment was 0.6 Oe, whereas NOL When inserted, it was 1.3 Oe, and when plasma treatment was performed, it was 0.7 Oe. The smaller the Hc of the magnetization free layer made of a soft magnetic material of CoFe and NiFe, the better. The secondary effect of not degrading Hc by plasma treatment as in this example was also obtained.

(Example 7):
Example 7 is the same as in Example 6 described above, in the case where no plasma treatment was performed on the bottom type spin valve film, the case where NOL was inserted, the case where the Ru / CoFe interface was plasma treated, the Ru / CoFe interface, and It shows the Cu layer thickness dependence of MR ratio (FIG. 12) and the Cu dependence of Cu layer thickness (FIG. 13) when the CoFe / Cu interface is plasma treated. In FIG. 12, the horizontal axis represents the Cu layer thickness (nm), the vertical axis represents MR (%), the horizontal axis in FIG. 13 represents the Cu layer thickness (nm), and the vertical axis represents Hin (Oe). As shown in FIG. 12 and FIG. 13, in the case of no plasma treatment, Hin increases as the Cu layer thickness decreases, and when the Cu layer thickness decreases to 2.1 nm or less, the MR ratio decreases. When only the CoFe interface is plasma-treated, and when the Ru / CoFe interface and the CoFe / Cu interface are plasma-treated, the high MR ratio is maintained even when the Hin layer vibrates with respect to the Cu layer thickness and the Cu layer thickness is reduced to 2 nm or less. To maintain.

(Example 8):
Example 8 is an MR curve major loop (FIG. 14) when the Ru / CoFe interface in the bottom type spin valve film is plasma-treated and the CoFe / Cu interface is plasma-treated in Example 6 above. The MR curve minor loop (FIG. 15) is shown. 14 and 15, the horizontal axis represents H (Oe) and the vertical axis represents MR (%). In this example, the Ru / CoFe interface is treated for 15 seconds and the CoFe / Cu interface is treated for 30 seconds. According to this example, a high MR ratio of 12%, a low Hin of −4 Oe, and a low Hc of 0.5 Oe were obtained.

(Example 9):
Example 10 shows an example in which the bias voltage Vdc to the substrate 25 which is a plasma condition is changed in the plasma treatment of the Ru / CoFe interface in the manufacturing method of the bottom type spin-valve giant magnetoresistive thin film in FIG. ing. According to this embodiment, it can be seen that the lower the bias voltage applied to the substrate 25 is, the lower Hin and the higher MR ratio are obtained.

  In the above embodiment and each example, the same effect can be achieved even if the Cu layer of the spin valve film is replaced with a so-called TMR film in which an Al oxide layer (AlOx layer) is replaced. Since the TMR film has a higher MR ratio than the GMR film, it is a magnetic multilayer film that is attracting attention as a next-generation magnetic reproducing head, and is also promising as a next-generation nonvolatile memory.

  In the embodiments and examples described above, when the laminated ferrimagnetic pinned layer is a multilayer film in which a nonmagnetic layer sandwiched between a magnetic layer and a magnetic layer is composed of two or more types of layers, nonmagnetic It is preferable to perform plasma treatment on at least one of the interfaces existing in the layer. Further, when the magnetization free layer is a multilayer film composed of two or more types of layers, it is preferable to perform plasma treatment on at least one of the interfaces existing in the magnetization free layer. Furthermore, when the antiferromagnetic layer is a multilayer film composed of two or more kinds of layers, it is preferable to perform plasma treatment on at least one of the interfaces existing in the antiferromagnetic layer.

  In the above-described embodiment, the plasma processing chamber 14 is specially used in the multi-chamber film forming apparatus 10 in order to perform plasma processing at an appropriate stage during the film formation of the multilayer structure of the spin valve type giant magnetoresistive thin film. However, the present invention is not limited to this. For example, the parallel-plate electrode structure shown in FIG. 2 or an ion irradiation structure may be provided in the film forming chambers 13A and 13B, and the plasma treatment may be performed in the film forming chamber.

  In the method of manufacturing a spin valve giant magnetoresistive thin film according to the present invention, the plasma treatment is performed on the predetermined interface selected as described above in the multilayer structure of the spin valve giant magnetoresistive thin film, thereby flattening and cleaning the interface. As a result, a high MR ratio is realized. However, in the multilayer structure, any one of all interfaces existing between the buffer film and the protective film, or any combination thereof is used. Of course, the effects of the present invention can be realized by plasma processing all the interfaces.

  In the above description, the invention has been explained only by grasping the invention from the viewpoint of the manufacturing method of the spin valve type giant magnetoresistive thin film, but the multilayer of the spin valve type giant magnetoresistive thin film made by the manufacturing method according to the present invention has been explained. The film structure itself has a unique film structure in which a predetermined interface is flattened and cleaned by plasma treatment or the like.

DESCRIPTION OF SYMBOLS 10 Film-forming apparatus 11 Substrate transfer robot 12 Vacuum transfer chamber 13A, 13B Film-forming chamber 14 Plasma processing chamber 15 Load lock chamber 21 Vacuum tank 22 Upper electrode 23 Lower electrode 25 Substrate 26 Plasma 31, 32 Target 41 Buffer layer 42 Antiferromagnetic Layer 43 Magnetization fixed layer 44 Nonmagnetic conductive layer 45 Magnetization free layer 47 Protective layer

Claims (14)

  A multi-layer portion comprising a buffer layer deposited on the substrate, a nonmagnetic conductive layer, a magnetization fixed layer and a magnetization free layer sandwiching the nonmagnetic conductive layer, and an antiferromagnetic layer formed adjacent to the magnetization fixed layer; In a method of manufacturing a spin valve type giant magnetoresistive thin film comprising a protective layer to be deposited, at least one of a plurality of interfaces formed between the nonmagnetic conductive layer and the buffer layer is plasma treated A manufacturing method of a spin valve type giant magnetoresistive thin film characterized by the above.   In the multilayer part, the magnetization fixed layer is formed on the substrate side and the magnetization free layer is formed on the protective layer side, and the magnetization fixed layer and / or the magnetization free layer is composed of a single layer or a plurality of layers, 2. The method for producing a spin valve giant magnetoresistive thin film according to claim 1, wherein at least one of a plurality of interfaces formed between the nonmagnetic conductive layer and the buffer layer is subjected to plasma treatment.   In the multilayer part, the magnetization free layer is formed on the substrate side, the magnetization fixed layer is formed on the protective layer side, and the magnetization fixed layer and / or the magnetization free layer is composed of a single layer or a plurality of layers, 2. The spin valve according to claim 1, wherein at least one of a plurality of interfaces formed between the nonmagnetic conductive layer and the buffer layer and a plurality of interfaces in the magnetization fixed layer is subjected to plasma treatment. Of manufacturing a giant magnetoresistive thin film.   In the multilayer portion, the magnetization fixed layer includes a lower magnetization fixed layer and an upper magnetization fixed layer, and the nonmagnetic conductive layer includes a lower nonmagnetic conductive layer and an upper nonmagnetic conductive layer, and the lower nonmagnetic conduction A five-layer structure is formed based on the lower magnetization fixed layer and the magnetization free layer sandwiching a layer and the magnetization free layer and the upper magnetization fixed layer sandwiching the upper nonmagnetic conductive layer, and the lower magnetization fixed At least one of the layer, the upper magnetization fixed layer, and the magnetization free layer includes a single layer or a plurality of layers, and a plurality of interfaces formed between the lower nonmagnetic conductive layer and the buffer layer, and 2. The method of manufacturing a spin-valve giant magnetoresistive thin film according to claim 1, wherein at least one of the interfaces between the upper nonmagnetic conductive layer and the magnetization free layer is subjected to plasma treatment.   In the manufacturing method of the bottom type spin-valve type giant magnetoresistive thin film that is successively laminated in the order of the buffer layer, antiferromagnetic layer, magnetization fixed layer, nonmagnetic conductive layer, magnetization free layer, and protective layer on the substrate, Plasma processing is performed on at least one of the interface between the buffer layer and the antiferromagnetic layer, the interface between the antiferromagnetic layer and the magnetization fixed layer, and the interface between the magnetization fixed layer and the nonmagnetic conductive layer. A manufacturing method of a spin valve type giant magnetoresistive thin film.   The magnetization fixed layer is a laminated ferrimagnetic fixed layer having a three-layer structure of a first magnetization fixed layer element and a second magnetization fixed layer element separated by a nonmagnetic layer, and the antiferromagnetic layer and the first magnetization fixed layer. The interface between the magnetization fixed layer element, the interface between the first magnetization fixed layer element and the nonmagnetic layer, the interface between the nonmagnetic layer and the second magnetization fixed layer element, the second magnetization fixed layer element and the nonmagnetic conductive layer 6. The method of manufacturing a spin valve type giant magnetoresistive thin film according to claim 5, wherein at least one of the interfaces is plasma-treated.   In the method of manufacturing a top type spin valve type giant magnetoresistive thin film that is continuously laminated in the order of a buffer layer, a magnetization free layer, a nonmagnetic conductive layer, a magnetization fixed layer, an antiferromagnetic layer, and a protective layer on a substrate, A method for producing a spin-valve giant magnetoresistive thin film, comprising plasma-treating at least one portion of an interface between the buffer layer and the magnetization free layer and an interface between the magnetization free layer and the nonmagnetic conductive layer.   The magnetization fixed layer is a laminated ferrimagnetic fixed layer having a three-layer structure of a first magnetization fixed layer element and a second magnetization fixed layer element separated by a nonmagnetic layer, and the first magnetization fixed layer element and the 8. The method of manufacturing a spin valve type giant magnetoresistive thin film according to claim 7, wherein plasma processing is performed on at least one of the interface between the nonmagnetic layer and the interface between the nonmagnetic layer and the second magnetization fixed layer element.   A buffer layer, a first antiferromagnetic layer, a first magnetization fixed layer, a first nonmagnetic conductive layer, a magnetization free layer, a second nonmagnetic conductive layer, a second magnetization fixed layer, a second antiferromagnetic layer on a substrate; In a method of manufacturing a dual type spin valve giant magnetoresistive thin film that is continuously laminated in the order of protective layers, the interface between the buffer layer and the first antiferromagnetic layer, the first antiferromagnetic layer, and the first Plasma processing is performed on at least one of an interface between one magnetization fixed layer, an interface between the first magnetization fixed layer and the first nonmagnetic conductive layer, and an interface between the magnetization free layer and the second nonmagnetic conductive layer. A manufacturing method of a spin valve type giant magnetoresistive thin film.   The first magnetization fixed layer is a first laminated ferrimagnetic structure having a three-layer structure of a first magnetization fixed layer element, a first nonmagnetic layer, and a second magnetization fixed layer element, and the second magnetization fixed layer has a third magnetization. A second laminated ferrimagnetic structure having a three-layer structure of a fixed layer element, a second nonmagnetic layer, and a fourth magnetization fixed layer element, the interface between the first antiferromagnetic layer and the first magnetization fixed layer element, An interface between one magnetization fixed layer element and the first nonmagnetic layer, an interface between the first nonmagnetic layer and the second magnetization fixed layer element, an interface between the second magnetization fixed layer element and the first nonmagnetic conductive layer, The plasma processing is performed on at least one of the interface between the third magnetization fixed layer element and the second nonmagnetic layer and the interface between the second nonmagnetic layer and the fourth magnetization fixed layer element. A manufacturing method of the described spin valve type giant magnetoresistive thin film.   The said buffer layer is a multilayer film comprised by the 2 or more types of layer, Plasma treatment is carried out to at least 1 place among the some interfaces which exist in the said buffer layer, The Claim 1 characterized by the above-mentioned. A method for producing a spin-valve giant magnetoresistive thin film according to item 1.   In the plasma treatment, plasma using RF waves of 13.56 MHz is used in a gas atmosphere of any of Ar, Kr, Xe, Ne and similar gases, which are inert gases having a low pressure of 0.01 to 100 Pa. 12. The method of manufacturing a spin valve type giant magnetoresistive thin film according to claim 1, wherein the electrode structure is a parallel-plate capacitively coupled type electrode. In the electrode structure, a substrate to be subjected to plasma processing is disposed on an electrode on a side to which the RF wave is applied, and a power applied by the RF wave is 0.5 W / cm ² or less per unit area, and a bias voltage applied to the substrate 13. The method for producing a spin-valve giant magnetoresistive thin film according to claim 12, wherein the voltage is in a range of less than 0V and not less than −300V.   13. The method for producing a spin valve giant magnetoresistive thin film according to claim 12, wherein the plasma treatment time is not longer than 1 minute.

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