JP2009055050A - Method for manufacturing spin-valve giant magnetoresistive film or tunnel magnetoresistive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing spin-valve giant magnetoresistive films or TMR films satisfying both high magnetoresistive change ratio (MR ratio) and low interlayer coupling magnetic field (Hin). <P>SOLUTION: In a method of manufacturing bottom type spin-valve giant magnetoresistive films or TMR films by film-forming and laminating an anti-ferromagnetic layer, a magnetization fixing layer, a non-magnetic conduction layer or oxide layer, and a magnetization free layer in this order, a step is added to plasma-process a preset laminated layer interface to reduce the interlayer coupling magnetic field acting between the magnetization fixing layer and the magnetization free layer. With this, a film of high MR ratio can be 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 techniques in vacuum include magnetron sputtering, ion beam sputtering, ECR sputtering, counter target sputtering, high frequency sputtering, electron beam evaporation, resistance heating evaporation, and MBE (Molecular Beam Epitaxy).

  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 in practical use of the magnetic reproducing head of the magnetic disk drive device, and the magnetic field having a value included in the range of −10 to +10 Oe. 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.

  Further, in the conventional technique, in a bottom type spin valve film, a ferromagnetic oxide generated between a magnetization fixed layer and a magnetization free layer by inserting a very thin oxide layer (NOL: Nano oxide layer) of 1 nm or less into the magnetization fixed layer. A technique for reducing binding has 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 when 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.

First manufacturing how the antiferromagnetic layer, the magnetization fixed layer, a nonmagnetic conductive layer or an oxide layer, magnetization free layer bottom type spin-valve type giant magnetoresistive thin film or a TMR film laminated with films in the order of In this manufacturing method, the film formation is interrupted for at least one of the interface between the antiferromagnetic layer and the magnetization fixed layer, and the interface between the magnetization fixed layer and the nonmagnetic conductive layer or the oxide layer. By performing plasma treatment exposed to plasma of an inert gas, the flatness and normality of each layer are improved, thereby enabling a high MR ratio and a low Hin.

In the second manufacturing method, an antiferromagnetic layer, a magnetization fixed layer, a nonmagnetic conductive layer or oxide layer, and a magnetization free layer are formed and stacked in this order, and the magnetization fixed layer is separated by a nonmagnetic layer. In the method of manufacturing a bottom type spin-valve giant magnetoresistive thin film or TMR film as a laminated ferrimagnetic pinned layer having a three-layer structure of the first pinned magnetic layer element and the second pinned magnetic layer element, interface between the magnetic layer first magnetization fixed 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 pinning layer element, said second magnetization pinning layer element And at least one of the interfaces between the nonmagnetic conductive layer and the oxide layer is subjected to plasma treatment in which film formation is interrupted and exposed to plasma of an inert gas.

The third manufacturing method is a top-type spin-valve giant magnetoresistive in which a magnetization free layer, a nonmagnetic conductive layer or oxide layer, a magnetization fixed layer, and an antiferromagnetic layer are deposited and laminated on a substrate in this order. the method of manufacturing a thin film, with respect to the interface of the said and the magnetization free layer nonmagnetic conductive layer or an oxide layer, a method of performing plasma processing of exposing to suspend deposition plasma of an inert gas.

In the fourth manufacturing method, a magnetization free layer, a nonmagnetic conductive layer or oxide layer, a magnetization pinned layer, and an antiferromagnetic layer are formed and laminated on a substrate, and the magnetization pinned layer is In the method of manufacturing a top-type spin-valve giant magnetoresistive thin film as a laminated ferrimagnetic fixed layer having a three-layer structure of a first fixed magnetization layer element and a second fixed magnetization layer element separated by a magnetic layer, the interface between the first magnetization pinned layer element and the non-magnetic layer, wherein for at least one location of the interface between the nonmagnetic layer and the second magnetization pinning layer element, a plasma treatment of exposure to the plasma of the inert gas to interrupt the deposition It is characterized by performing.

In the fifth manufacturing method, on the substrate, the first antiferromagnetic layer, the first magnetization fixed layer, the first nonmagnetic conductive layer or the first oxide layer, the magnetization free layer, the second nonmagnetic conductive layer, or the second oxide layer, the second magnetization fixed layer, in the manufacturing method of the second antiferromagnetic layer sequentially deposited by laminated dual type spin-valve giant magnetoresistive thin film or a TMR film, the first antiferromagnetic layer interface of the first magnetization pinned layer and the interface of the first magnetization pinned layer and the first non-magnetic conducting layer or said first oxide layer, the magnetization free layer and the second nonmagnetic conductive layer or the second In this method, plasma treatment is performed in which at least one portion of the interface with the oxide layer is interrupted and exposed to plasma of an inert gas.

In the sixth manufacturing method, the first antiferromagnetic layer, the first magnetization fixed layer, the first nonmagnetic conductive layer or the first oxide layer, the magnetization free layer, the second nonmagnetic conductive layer or the second on the substrate. The oxide layer, the second magnetization fixed layer, and the second antiferromagnetic layer are formed and stacked in this order, and the first magnetization fixed layer is formed of a first magnetization fixed layer element, a first nonmagnetic layer, and a second layer. The first laminated ferrimagnetic layer has a three-layer structure of a fixed magnetization layer element, and the second fixed magnetization layer has a three-layer structure of a third fixed magnetization layer element, a second nonmagnetic layer, and a fourth fixed magnetization layer element. in the second method for fabricating laminated ferrimagnetic and the dual type of spin-valve giant magnetoresistive thin film or a TMR film, the said first magnetization pinning layer element interface between the first nonmagnetic layer, the first nonmagnetic layer the interface of the second magnetization pinned layer element, said second magnetization pinning layer element and the first non-magnetic conductive layer or the first acid The interface between the object layer, the interface between the third magnetization fixed layer element and the second non-magnetic layer, for at least one location of the interface between the second non-magnetic layer and the fourth magnetization fixed layer element, the deposition It is characterized by performing plasma treatment that is interrupted and exposed to an inert gas plasma.

Manufacturing method of the seventh, in each manufacturing method described above has a buffer layer of a multilayer film constituted by two or more layers, against the at least one portion of the plurality of interfaces present in the buffer layer, A plasma treatment is performed in which the film formation is interrupted and exposed to an inert gas plasma.

Manufacturing method of the eighth, in each manufacturing process of the plasma treatment of the above SL is an inert gas of a low pressure 0.01~100Pa Ar, Kr, Xe, gas similar like and these Ne A plasma using a 13.56 MHz RF wave is used in any of the gas atmospheres, and the electrode structure is a parallel plate capacitive coupling type.

Manufacturing method of the ninth, said the eighth production method, electrodeposition in pole structure, the substrate to be plasma processed side electrode providing an RF wave is disposed, 0.5 W per power unit area by the RF waves / Cm ² or less, and the bias voltage applied to the substrate is a voltage included in the range of less than 0V and −300V or more.

In the eighth manufacturing method, the tenth manufacturing method is preferably characterized in that the plasma processing time is a time not exceeding one minute.

An eleventh manufacturing method is characterized in that, in each of the manufacturing methods described above, plasma treatment is performed by exposing the plasma to an inert gas using ion bombardment based on an ion irradiation structure.

  In the method for producing a spin valve type giant magnetoresistive thin film according to the present invention, the film formation is temporarily interrupted during the film formation of the spin valve film having a multilayer structure, and the interface is subjected to ion bombardment treatment, preferably plasma treatment. 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 the bottom type, the top type, and the dual spin valve, and the film thickness of the Cu layer is set to 2.1 nm. The spin valve film of bottom type, top type, dual spin valve 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. According to the structure, an interface for performing plasma treatment 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.

  According to the present invention, since the film formation is temporarily interrupted during 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 magnetization fixed layer formed by sandwiching the nonmagnetic conductive layer And the magnetic coupling between the magnetization fixed layer and the magnetization free layer can be reduced to −10 to −10 even when the nonmagnetic conductive layer is thin. A high MR ratio can be obtained by maintaining the magnetic field within the range of +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.

  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) / The layers are successively laminated in the order of CoFe (1.5 nm) / NiFe (2.5 nm) / Cu (1 nm) / Ta (3 nm). 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 buffer layers 41, PtMn (12nm) is an antiferromagnetic layer 42, CoFe (1.8nm), Ru (0.8nm), and CoFe (2.8nm) are fixed magnetization. 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, Cu (1 nm) is a spin filter 46, Ta (3 nm) is This is a protective layer 47. In order to form a bottom type spin valve film as described above, first, Ta (3 nm) is formed in the film forming chamber 13B, and then NiFe (2 nm) / PtMn (12 nm) / CoFe is formed in the film forming 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 in the deposition chamber 13B. Cu (2.2 nm) is deposited, then CoFe (1.5 nm) / NiFe (2.5 nm) is deposited in the deposition chamber 13A, and finally Cu (1 nm) / Ta (3 nm) is deposited in the deposition chamber 13B. Form a film.

  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 film forming process of the bottom type spin valve film, for example, when the Ru (0.8 nm) / CoFe (2.8 nm) interface is subjected to plasma treatment, it 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 in the deposition chamber 13B. After forming the Ru (0.8 nm) film, it is transferred to the plasma processing chamber 25 and subjected to the plasma processing based on the processing conditions described above, and then CoFe (2.8 nm) is formed in the film forming chamber 13A. 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 Cu (1 nm) / is deposited in the deposition chamber 13B. Ta (3 nm) is deposited.

  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 type 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 (1.5 nm) This is an example in which plasma processing is performed in the middle of film formation by a manufacturing method of a bottom type spin valve film having a laminated structure of / 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. For this reason, 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 (3nm) / NiFe (2nm) / PtMn (12nm) / CoFe (1.8nm) / Ru (0.8nm) / CoFe (2.8nm) / Cu (2.2nm) / CoFe (1.5nm) / NiFe (2.5nm) In the bottom type spin valve film having a stacked structure of / Cu (1 nm) / Ta (3 nm), the interface of NiFe (2 nm) / PtMn (12 nm), the interface of PtMn (12 nm) / CoFe (1.8 nm), CoFe (1.8 nm) nm) / Ru (0.8 nm) interface, Ru (0.8 nm) / CoFe (2.8 nm) interface, and CoFe (2.8 nm) / Cu (2.2 nm) interface to reduce the Hin. An improvement in MR ratio is 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, from the substrate 25 side, 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) is an example in which plasma treatment is performed in the middle of film formation by a method for producing a top type spin valve film having a laminated structure. In this stacked 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. The MR ratio was improved in the plasma treatment of 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 in which the plasma processing time in the method for manufacturing the bottom type spin valve giant magnetoresistive thin film shown in FIG. 3 is changed will be described. 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 processing time of the Ru / CoFe interface is changed, the plasma processing time of 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(3nm)/CoFe(0.5nm)/Cu(2.2nm)/CoFe(2.8nm)/Ru(0.8nm)/CoFe(1.8nm)/PtMn(12nm)/Ta(3nm) 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. 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, CoFe (2.8 nm) / Ru (0.8 nm) / CoFe (1.8 nm) is the second magnetization fixed layer (second laminated ferri) 43B, and PtMn (12 nm) is the first 2 The antiferromagnetic layer 42B, Ta (3 nm) is the protective layer 47. In FIG. 9, the horizontal axis is “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 example, the plasma treatment time was unified to 15 seconds and the plasma treatment interface was changed. When the plasma treatment was performed on the three interfaces of the Ru / CoFe interface, the Cu / CoFe interface, and the Ru / CoFe interface, the reduction of Hin was achieved. And improved MR ratio. Therefore, in the film configuration of this example, 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 in which the plasma processing time in the method for manufacturing the bottom type spin valve giant magnetoresistive thin film shown in FIG. 3 is changed will be described. FIG. 10 is a characteristic diagram showing changes in MR ratio and Hin when the horizontal axis is the plasma processing time (second; 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 can be seen that the plasma treatment 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 above-mentioned bottom type spin valve type giant magnetoresistive thin film shown in FIG. 3, no plasma treatment was performed, and Ru (0.8 nm) and CoFe (2.8 nm) of CoFe oxide layer (NOL) with a thickness of 1 nm or less, and Ru (0.8 nm) / CoFe (2.8 nm) interface for 15 seconds plasma treatment A comparison of MR curves is shown. In FIG. 11, the horizontal axis indicates the magnetic field strength, the vertical axis indicates the MR ratio, and the NOL is sandwiched between the MR curve 51 when no plasma treatment is performed and Ru (0.8 nm) and CoFe (2.8 nm). The MR curve 52 in this case and the MR curve 53 when the 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. The same effect can be obtained by forming a CoFe layer having a thickness of 1 to 4 nm after inserting the NOL and then performing plasma treatment. Further, 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 the plasma treatment was 0.6 Oe, whereas NOL was inserted. When the plasma treatment was performed, the value was 1.3 Oe. The smaller the Hc of the magnetization free layer composed of the soft magnetic material of CoFe and NiFe, the better. The secondary effect that the Hc is not deteriorated by the 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 of no plasma treatment in the bottom type spin valve film, in the case of inserting NOL, and in the case of plasma treatment of the Ru / CoFe interface. FIG. 9 shows the dependency of the MR ratio on the Cu layer thickness (FIG. 12) and the dependency of Hin on the Cu layer thickness (FIG. 13) when the Ru / CoFe interface and the CoFe / Cu interface are 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, but Ru / CoFe When only the interface is plasma-treated, and when the Ru / CoFe interface and the CoFe / Cu interface are plasma-treated, Hin vibrates with respect to the Cu layer thickness, and a high MR ratio is obtained even when the Cu layer thickness is reduced to 2 nm or less. maintain.

  (Example 8): Example 8 is an MR curve measure in the case where 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. A loop (FIG. 14) and an MR curve minor loop (FIG. 15) are 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: In Example 10, the bias voltage Vdc applied to the substrate 25 which is a plasma condition in the plasma processing of the Ru / CoFe interface in the manufacturing method of the bottom type spin-valve giant magnetoresistive thin film shown in FIG. The example which changed is shown. 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-described 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.

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 the 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. FIG. 7 shows a seventh embodiment of the present invention, in the case of no plasma processing in a bottom type spin-valve giant magnetoresistive thin film, when NOL is inserted, when Ru / CoFe interface is plasma-treated, and Ru / CoFe interface FIG. 5 is a characteristic diagram showing the dependence of the MR ratio on the Cu layer thickness when the CoFe / Cu interface is plasma treated. FIG. 7 shows a seventh embodiment of the present invention, in the case of no plasma processing in a bottom type spin-valve giant magnetoresistive thin film, when NOL is inserted, when Ru / CoFe interface is plasma-treated, and 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. The characteristic diagram which shows 8th Example of this invention and shows the MR curve minor 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. The characteristic view which shows 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.

Explanation of symbols

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 (11)

In the manufacturing method of the bottom type spin-valve giant magnetoresistive thin film or TMR film in which the antiferromagnetic layer, the magnetization fixed layer, the nonmagnetic conductive layer or oxide layer, and the magnetization free layer are laminated in this order,
Inactive gas plasma by interrupting film formation on at least one of the interface between the antiferromagnetic layer and the magnetization fixed layer and the interface between the magnetization fixed layer and the nonmagnetic conductive layer or the oxide layer. A method for producing a spin-valve giant magnetoresistive thin film or TMR film, characterized by performing a plasma treatment that is exposed to water. An antiferromagnetic layer, a magnetization fixed layer, a nonmagnetic conductive layer or oxide layer, and a magnetization free layer are formed and stacked in this order, and the magnetization fixed layer is separated by a nonmagnetic layer. In a method of manufacturing a bottom type spin valve type giant magnetoresistive thin film or TMR film as a laminated ferrimagnetic fixed layer having a three-layer structure of an element and a second magnetization fixed layer element,
The interface between the antiferromagnetic layer and the first 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 A spin-valve type characterized in that plasma treatment is performed on at least one portion of the interface between the fixed layer element and the nonmagnetic conductive layer or the oxide layer , and the film formation is interrupted and exposed to an inert gas plasma. Manufacturing method of giant magnetoresistive thin film or TMR film. In the method of manufacturing a top type spin valve giant magnetoresistive thin film formed by laminating and laminating on a substrate in the order of a magnetization free layer, a nonmagnetic conductive layer or oxide layer, a magnetization fixed layer, and an antiferromagnetic layer ,
A spin-valve giant magnetoresistive thin film or TMR, characterized in that plasma treatment is performed on the interface between the magnetization free layer and the nonmagnetic conductive layer or oxide layer by interrupting film formation and exposing to an inert gas plasma. A method for producing a membrane. A magnetic free layer, a nonmagnetic conductive layer or oxide layer, a magnetization fixed layer, and an antiferromagnetic layer are formed and stacked on the substrate, and the magnetization fixed layer is separated by a nonmagnetic layer. In a method of manufacturing a top type spin valve type giant magnetoresistive thin film having a laminated ferrimagnetic fixed layer having a three-layer structure of one magnetization fixed layer element and a second magnetization fixed layer element,
At least one of the interface between the first magnetization pinned layer element and the nonmagnetic layer and the interface between the nonmagnetic layer and the second magnetization pinned layer element is interrupted and exposed to an inert gas plasma. A method for producing a spin valve giant magnetoresistive thin film or TMR film, characterized by performing plasma treatment. On the substrate, a first antiferromagnetic layer, a first magnetization pinned layer, a first nonmagnetic conductive layer or first oxide layer, a magnetization free layer, a second nonmagnetic conductive layer or second oxide layer, a second magnetization In the manufacturing method of the dual type spin valve type giant magnetoresistive thin film or TMR film formed by laminating the fixed layer and the second antiferromagnetic layer in this order ,
The interface between the first antiferromagnetic layer and the first magnetization pinned layer, the interface between the first magnetization pinned layer and the first nonmagnetic conductive layer or the first oxide layer, the magnetization free layer and the second nonmagnetic layer A spin-valve giant magnetoresistive thin film characterized in that at least one portion of the interface with the magnetic conductive layer or the second oxide layer is subjected to plasma treatment in which film formation is interrupted and exposed to an inert gas plasma. Or the manufacturing method of a TMR film | membrane. On the substrate, a first antiferromagnetic layer, a first magnetization pinned layer, a first nonmagnetic conductive layer or first oxide layer, a magnetization free layer, a second nonmagnetic conductive layer or second oxide layer, a second magnetization A fixed layer and a second antiferromagnetic layer are formed and stacked in this order, and the first magnetization fixed layer is composed of three layers of a first magnetization fixed layer element, a first nonmagnetic layer, and a second magnetization fixed layer element. The first laminated ferri has a structure, and the second magnetization fixed layer is a second laminated ferri that has a three-layer structure of a third magnetization fixed layer element, a second nonmagnetic layer, and a fourth magnetization fixed layer element. In the manufacturing method of the dual type spin valve type giant magnetoresistive thin film or TMR film,
An interface between the first magnetization fixed layer element and the first nonmagnetic layer, an interface between the first nonmagnetic layer and the second magnetization fixed layer element, the second magnetization fixed layer element and the first nonmagnetic conductive layer, or an interface between the first oxide layer, the interface between the third magnetization fixed layer element and the second non-magnetic layer, for at least one location of the interface between the second non-magnetic layer and the fourth magnetization fixed layer element A method for producing a spin-valve giant magnetoresistive thin film or TMR film, wherein plasma treatment is performed by interrupting film formation and exposing to plasma of an inert gas. It has a buffer layer of a multilayer film constituted by two or more layers, against the at least one portion of the plurality of interfaces present in the buffer layer is exposed to a plasma of inert gas is interrupted the deposition plasma The method for producing a spin valve giant magnetoresistive thin film or TMR film according to any one of claims 1 to 6 , wherein the treatment is performed. The plasma treatment uses plasma using 13.56 MHz RF waves in a gas atmosphere of any one of Ar, Kr, Xe, and Ne, which is an inert gas having a low pressure of 0.01 to 100 Pa. The method for producing a spin-valve giant magnetoresistive thin film or TMR film according to any one of claims 1 to 7 , characterized in that is a parallel-plate capacitively coupled type. In the electrode structure, a substrate to be subjected to plasma processing is disposed on an electrode on the 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 9. The method for producing a spin valve giant magnetoresistive thin film or TMR film according to claim 8, wherein the voltage falls within a range of less than 0V and not less than −300V. 9. The method of manufacturing a spin valve type giant magnetoresistive thin film or TMR film according to claim 8, wherein the plasma treatment time is not longer than 1 minute. The spin-valve giant magnetoresistive thin film or TMR film according to any one of claims 1 to 10 , wherein plasma treatment is performed by exposing to an inert gas plasma using ion bombardment based on an ion irradiation structure. Manufacturing method.

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