KR100448989B1 - Top and bottom type spin valves with good thermal stability and its fabrication method - Google Patents

Abstract

The present invention relates to the manufacture of a spin valve magnetoresistive thin film having improved thermal characteristics, and by introducing an appropriate oxide layer in the spin valve magnetoresistive thin film structure, blocking the diffusion of elements generated in each layer and preventing the movement of the layer to another layer. The present invention relates to a spin valve magnetoresistive thin film having an improved magnetoresistance ratio by improving and forming a uniform oxide layer through heat treatment after deposition, and a method of manufacturing the same.

Description

TOP AND BOTTOM TYPE SPIN VALVES WITH GOOD THERMAL STABILITY AND ITS FABRICATION METHOD}

The present invention relates to the manufacture of a spin valve magnetoresistive thin film having improved thermal characteristics, and by forming an appropriate oxide layer in the spin valve magnetoresistive thin film structure to block diffusion occurring in each layer, thereby preventing movement to another layer. In addition, the present invention relates to a spin valve magnetoresistive thin film having an increased magnetoresistance ratio by forming a uniform oxide layer through heat treatment after deposition and a method of manufacturing the same.

1 is a schematic view of an exchange bias type spin valve magnetoresistive thin film structure including an oxide layer. As shown in the figure, a typical spin valve magnetoresistive thin film has a structure of ferromagnetic layer / nonmagnetic layer / ferromagnetic layer / antiferromagnetic layer or antiferromagnetic layer / ferromagnetic layer / nonmagnetic layer / ferromagnetic layer on the substrate. That is, one layer (free layer) of the two ferromagnetic thin films separated by the nonmagnetic thin film is free to rotate while the other layer (constrained layer) is fixed by the antiferromagnetic thin film. Therefore, the magnetoresistance of the spin valve magnetoresistive thin film varies depending on whether the magnetization of the two magnetic layers is antiparallel or parallel to the external magnetic field. In general, the giant magnetoresistive effect is spin-dependent scattering, which has a large resistance when the arrangement of two magnetic layers is antiparallel, and a low resistance when parallel. The advantage of the exchange bias type spin valve magnetoresistive thin film structure is that a large magnetoresistance can be obtained even in the magnetic field where the magnetization arrangement of the free layer and the constrained layer is low, and when the antiferromagnetic layer and the ferromagnetic layer are in contact with each other, An exchange bias is generated, and a large value is advantageous for device fabrication and excellent thermal characteristics. Therefore, much research has been made to develop a new antiferromagnetic thin film having improved thermal properties, that is, high magnetic anisotropy intensity (Hex) and high blocking temperature (T _b ). However, for example, FeMn antiferromagnetic materials, which are proposed as antiferromagnetic materials, have been pointed out to have low blocking temperature and corrosiveness. For example, IrMn, PtMn, and NiMn having a large exchange magnetic field all increase Mn through grain boundaries when the temperature rises. This problem is pointed out as a problem that the magnetic resistance and the exchange bias are lowered due to the diffusion and movement to the space layer, which is a pinned layer and a nonmagnetic layer. Meanwhile, NiO and α-Fe ₂ O ₃ using oxides are also proposed as antiferromagnetic materials. However, in order to reproduce high-density information during head manufacturing, the thickness of the head should be reduced, but strong exchange is performed using the oxide antiferromagnetic materials. To make a bias, the head is thicker, which is disadvantageous for high density recording. Such a conventional spin valve magnetoresistive thin film structure has a magnetoresistance of 5 to 6% or less, and a low thermal characteristic is pointed out as a disadvantage, and thus there is a limit to coping with high density.

On the other hand, a simple spin valve magnetoresistive thin film structure having two ferromagnetic layers and a fixed layer has a low magnetoresistance, and thus has a problem of achieving a recording density of 20 Gbit / in ^{2. Therefore} , in a practical structure, a thin ferromagnetic layer is inserted into a free layer in interfacial scattering. Increase the magnetic resistance. However, this also requires a magnetoresistance of 10% or more due to low magnetoresistance to achieve high recording density of 40 Gbit / in ² or more.

In order to solve the problems of low blocking temperature and low magnetoresistance of the antiferromagnetic material, an object of the present invention is to prevent diffusion of Mn generated in the antiferromagnetic layer as the temperature rises, thereby providing excellent thermal characteristics and high magnetoresistance ratio. Disclosed is a spin valve magnetoresistive thin film suitable for achieving recording density and a method of manufacturing the same.

1 is a schematic diagram of a top and bottom type spin valve magnetoresistive thin film structure including an oxide layer. a shows the top spin valve structure and b shows the bottom spin valve structure.

Figure 2 shows the change in the magnetoresistance ratio according to the heat treatment temperature of the tower spin valve magnetoresistive thin film sample.

FIG. 3 shows the change of exchange magnetic anisotropy intensity according to the heat treatment temperature of the tower spin valve magnetoresistive thin film sample.

Figure 4 shows the change in the magnetoresistance ratio with the heat treatment temperature of the bottom-type spin valve magnetoresistive thin film sample.

5 shows the change of exchange magnetic anisotropy intensity according to the heat treatment temperature of the bottom-type spin valve magnetoresistive thin film sample.

Figure 6 shows the change in the magnetoresistance ratio with the heat treatment temperature of the bottom-type spin valve magnetoresistive thin film using IrMn as the antiferromagnetic layer.

FIG. 7 illustrates the sputter depth side composition distribution of Mn elements of a bottom-type spin valve magnetoresistive thin film using FeMn as an antiferromagnetic layer through secondary ion mass spectroscopy.

FIG. 8 shows the change in the magnetoresistance ratio of the bottom type spin valve magnetoresistive thin film using IrMn as an antiferromagnetic layer according to the partial pressure ratio of nitrogen gas and oxygen gas.

FIG. 9 illustrates a change in the magnetoresistance ratio of a bottom-type spin valve magnetoresistive thin film using IrMn as an antiferromagnetic layer according to a partial pressure ratio of argon gas and oxygen gas.

In order to achieve the above object, the present invention provides a spin valve magnetoresistive thin film and a manufacturing method thereof with improved thermal characteristics. More specifically, by forming an appropriate oxide layer in the spin valve magnetoresistive thin film structure, thermal properties are prevented by blocking the diffusion of elements occurring in each layer, in particular the diffusion of Mn occurring in the antiferromagnetic layer, to prevent them from moving to other layers. The present invention provides a spin valve magnetoresistive thin film having improved magnetoresistance ratio by depositing a uniform oxide layer by heat treatment in a vacuum to which the magnetic field is applied, and a method of manufacturing the same.

The present invention can be achieved in the conventional spin valve magnetoresistive thin film structure by depositing the remaining magnetic layer by oxidizing the middle of the ferromagnetic layer in contact with the antiferromagnetic layer under appropriate conditions to form an oxide layer when laminating the spin valve magnetoresistive thin film structure. The present invention provides a spin valve magnetoresistive thin film having excellent thermal characteristics and high magnetoresistance ratio and a method of manufacturing the same.

First, the present invention provides a top type and bottom type spin valve magnetoresistive thin film structure having excellent thermal characteristics and high magnetoresistance ratio. In the present invention, the tower type and bottom type spin valve magnetoresistive thin films are classified according to the position of the antiferromagnetic layer in the spin valve structure. The top ferromagnetic layer is located at the top and the bottom is called the bottom type. .

The top spin valve magnetoresistive thin film of the present invention has a structure in which a buffer layer, a first ferromagnetic layer, a nonmagnetic layer, a second ferromagnetic layer, an oxide layer, a second ferromagnetic layer, an antiferromagnetic layer, and a protective layer are sequentially stacked on a substrate. The bottom-type spin valve magnetoresistive thin film is a structure in which a buffer layer, a first ferromagnetic layer, an antiferromagnetic layer, a second ferromagnetic layer, an oxide layer, a second ferromagnetic layer, a nonmagnetic layer, a third ferromagnetic layer, and a protective layer are sequentially stacked on a substrate. In the present invention, the structure is deposited by direct current magnetron spattering, and an oxide layer is introduced during deposition. At this time, the introduced oxide layer serves to improve the thermal characteristics of the spin valve magnetoresistive thin film by blocking the diffusion of Mn generated in the anti-ferromagnetic layer to prevent migration to another layer.

The structure of the tower type and bottom type spin valve magnetoresistive thin film will be described in detail as follows.

As the substrate, a silicon substrate naturally having an oxide, an Si substrate or an artificially treated oxide or nitride substrate can be used. The buffer layer is formed by depositing Ta, Cu, Au, Al, Pd, or Pt with a thickness of 5 to 200 Å, and the magnetic core and antiferromagnetic layer deposited thereafter are used to maintain an excellent magnetoresistance ratio. The structure in which the (111) plane of the buffer layer having the first growth is preferred. As such, when the (111) plane of the buffer layer is first grown, exchange magnetic anisotropy is also obtained, and the magnetoresistance ratio is also increased. Therefore, the preferential growth of the (111) plane of the buffer layer is an important factor, and it is preferable that the structure of the buffer layer favors the formation of the (111) texture. The first ferromagnetic layer and the third ferromagnetic layer are preferably NiFe, CoFe or NiFe / CoFe. If the thickness of the ferromagnetic layer is 10 10 or less, the spin-dependent scattering efficiency is reduced to reduce the magnetoresistance ratio. If the ferromagnetic layer is 200 Å or more, the shunting effect of the current is increased to reduce the magnetoresistance ratio. Therefore, the ferromagnetic layer is preferably formed by depositing a thickness of 10 ~ 200 Å. The nonmagnetic layer is preferably formed by depositing Cu to a thickness of 15 to 60 kPa. If the Cu thickness is 15 Å or less, the interlayer coupling field must be increased to increase the bias current in actual use, which is disadvantageous to the application. If the thickness is 60 Å or more, the effect of classifying the current increases and the magnetoresistance is increased. The disadvantage is that the ratio is very reduced. Therefore, preferable Cu thickness is 15-60 GPa. The second ferromagnetic layer adjacent to the antiferromagnetic layer is preferably formed by depositing CoFe or NiFe with a total thickness of 20 to 200 GPa. The oxide layer is formed in the middle of the second ferromagnetic layer. The formation of the oxide layer prevents the diffusion of Mn generated in the antiferromagnetic layer as the temperature rises, thereby preventing the oxide layer from moving to another layer. Thermal properties are improved. As such, in order to improve the thermal characteristics of the spin valve magnetoresistive thin film, the thickness of the oxide layer must be very thin, and the thickness of the oxide layer is preferably within the range of 5 to 20 kPa. If the thickness of the oxide layer is 20 Å or more, the oxide layer tends to break the magnetic layer so that the magnetic layer does not exhibit the same characteristics. If the thickness of the oxide layer is 5 산화 or less, the oxide layer does not form an insulating layer having specular reflection and exhibits the characteristics of a single magnetic layer. Not preferred. The material of the oxide layer is considered to be closer to the magnetic oxide layer than to the insulating layer. The anti-ferromagnetic layer is preferably formed by depositing FeMn, IrMn, PtMn or PdPtMn to a thickness of 50 ~ 400Å. If the thickness of the antiferromagnetic layer is 50 두께 or less, it does not have a role of anti-ferromagneticity and thus does not generate exchange magnetic anisotropy. Therefore, the thickness of the antiferromagnetic layer is preferably 50 to 400 Pa. The protective layer is preferably formed by depositing Ta, Cu, oxide or nitride to a thickness of 10 ~ 200Å.

As a specific example of the spin valve magnetoresistive thin film according to the present invention, a Ta / NiFe / CoFe / Cu / CoFe / Nano (Nano Oxide Layer) / CoFe / half layer is formed on a Si substrate (a substrate having natural oxides or artificially oxides). Top type spin valve magnetoresistive thin film with ferromagnetic layer / Ta deposited and bottom type spin valve magnetoresistive thin film with Ta / NiFe / antiferromagnetic layer / CoFe / NOL / CoFe / Cu / CoFe / NiFe / Ta deposited structure Can be mentioned.

In forming the oxide layer, an oxide layer can be formed between the free layers. If the ferromagnetic layer used in the free layer, for example, CoFe or NiFe is used alone, an oxide layer is formed between CoFe or NiFe, and a NiFe / CoFe double free layer. If used, an oxide layer can be formed on the thicker side of the double free layer. However, since the free layer depends on the regeneration characteristics in manufacturing the sensor, the soft magnetic characteristics should be excellent, so that the insertion of the oxide layer should not cause the soft magnetic characteristics to be degraded. Therefore, forming the oxide layer on the free layer requires more rigorous experimentation. Therefore, it is preferable to introduce an oxide layer into the ferromagnetic layer adjacent to the antiferromagnetic layer, that is, the layer to be bound.

In addition, the present invention provides a method for producing a top- and bottom-type spin valve magnetoresistive thin film having excellent thermal properties by oxidizing the middle of the second ferromagnetic layer adjacent to the antiferromagnetic layer to form an oxide layer.

Method of manufacturing a top spin valve magnetoresistive thin film having a buffer layer / first ferromagnetic layer / non-magnetic layer / second ferromagnetic layer / oxide layer / second ferromagnetic layer / antiferromagnetic layer / protective layer structure according to the present invention 1) Ta on the substrate , Cu, Au, Al, Pd or Pt deposited to a thickness of 5 ~ 200Å to form a buffer layer having a structure that favors the deposition of (111) texture, 2) NiFe, CoFe or NiFe on the buffer layer / CoFe deposited to 10 ~ 200 10 thickness to form a first ferromagnetic layer, 3) to form a nonmagnetic layer by depositing Cu 15 ~ 60Å thickness on the first ferromagnetic layer adjacent to the buffer layer, 4) the Deposition of CoFe or NiFe with a total thickness of 20 ~ 200Å over the nonmagnetic layer to form a second ferromagnetic layer, depositing some of the ferromagnetic layer, 5) oxidizing the oxide layer by oxidizing the surface of the partially deposited ferromagnetic layer After forming, CoFe or Depositing the remainder of the second ferromagnetic layer with NiFe to form an oxide layer in the middle of the second ferromagnetic layer, 6) depositing FeMn, IrMn, PtMn, or PdPtMn on the ferromagnetic layer to a thickness of 50 to 400 GPa Forming a layer and 7) depositing Ta, Cu, oxide, nitride, or the like on the ferromagnetic layer to a thickness of 10 to 200 Å.

In addition, a bottom-type spin valve magnetoresistive thin film having a structure of a buffer layer / first ferromagnetic layer / antiferromagnetic layer / second ferromagnetic layer / oxidation layer / second ferromagnetic layer / nonmagnetic layer / third ferromagnetic layer / protective layer according to the present invention 1) forming a buffer layer having a structure that favors (111) texture formation by depositing Ta, Cu, Au, Al, Pd or Pt on a substrate in a thickness of 5 to 200 Å. Forming a first ferromagnetic layer by depositing NiFe, CoFe, or NiFe / CoFe on the buffer layer in a thickness of 10 to 200Å, and 3) depositing FeMn, IrMn, PtMn, or PdPtMn on the first ferromagnetic layer to a thickness of 50 to 400Å. Forming an antiferromagnetic layer, and 4) depositing a portion of the ferromagnetic layer by depositing CoFe or NiFe with a total thickness of 20 to 200Å over the antiferromagnetic layer to form a second ferromagnetic layer. Oxidation by oxidizing the surface of partially deposited ferromagnetic layer After forming the step, depositing the remaining ferromagnetic layer with CoFe or NiFe, to form an oxide layer in the middle of the second ferromagnetic layer, 6) by depositing a Cu 15 ~ 60 15 thickness on the ferromagnetic layer to form a nonmagnetic layer, 7) forming a third ferromagnetic layer by depositing NiFe, CoFe or NiFe / CoFe on the nonmagnetic layer to a thickness of 10 ~ 200Å and 8) Ta, Cu, oxide or nitride on the ferromagnetic layer to a thickness of 10 ~ 200Å Depositing to form a protective layer.

The structure was deposited by direct current magnetron spattering. Commonly used deposition methods include RF sputtering, ion beam spattering, and the like in addition to the direct current magnetron method. In the present invention, the DC sputtering method is adopted among them, but this is only because the DC magnetron method is generally evaluated to have a stable plasma state compared to other methods, and may be deposited by RF sputtering or ion beam spattering. Do.

The method for manufacturing a spin valve magnetoresistive thin film according to the present invention provides a method for manufacturing a spin valve magnetoresistive thin film having excellent thermal characteristics, wherein an oxide layer is introduced in the middle of a second ferromagnetic layer adjacent to an antiferromagnetic layer during deposition. The middle of the second ferromagnetic layer adjacent to the diamagnetic layer is oxidized in an oxygen atmosphere, an oxygen / nitrogen atmosphere in which oxygen and nitrogen are mixed in an appropriate ratio, or an oxygen / inert gas atmosphere in which oxygen and an inert gas are mixed in an appropriate ratio to form an oxide layer. . At this time, although the partial pressure ratio of oxygen and nitrogen is 9: 1 to 1: 9, the range of 9 (oxygen): 1 (nitrogen)-5 (oxygen): 5 (nitrogen) is preferable at a partial pressure ratio. As such, when oxygen and nitrogen are mixed, the roughness of the oxide layer is reduced by nitrogen to form a uniform oxide layer. However, when the partial pressure of nitrogen increases, the time for oxidation is greatly increased, so it is not preferable that the partial pressure of nitrogen in the nitrogen partial pressure of oxygen is rather high. Oxygen / nitrogen mixture or inert gas (for example, oxygen / nitrogen) in which the ratio of oxygen and nitrogen is 9 (oxygen): 1 (nitrogen) to 5 (oxygen): 5 (nitrogen) in the partial pressure ratio in forming the oxide layer. , Argon, etc.) and the ratio of oxygen to the partial pressure ratio is 9 (oxygen): 1 (inert gas) to 5 (oxygen): 5 (inert gas). Increase rain. This is because more homogeneous surface oxidation is caused by nitrogen or inert gas, which makes the specular reflectivity increase by making it smoother while reducing the roughness of the interface between the oxide layer and the CoFe layer for specular reflection. The formed oxide layer serves to improve the thermal characteristics of the spin valve magnetoresistive thin film sample by blocking the diffusion of Mn generated in the anti-ferromagnetic layer as the temperature increases to prevent the movement to another layer. At this time, the thickness of the oxide layer is preferably in the range of 5 to 20 Pa.

The oxidation method commonly used in the formation of the oxide layer includes a natural oxidation method, a DC or RF plasma oxidation method, and the like. Since the thickness of the oxide layer formed in the present invention is very thin, it is very difficult to control the thickness of the oxide layer when the plasma oxidation method is used. However, the natural oxidation method exposes the sample only to an oxygen atmosphere, an atmosphere in which oxygen and nitrogen are mixed, or an atmosphere in which oxygen and an inert gas are mixed, which is very advantageous to form an oxide layer having a small interface roughness. Therefore, in the exemplary embodiment of the present invention, a spin valve magnetoresistive thin film structure having excellent thermal characteristics and an increased magnetoresistance ratio was fabricated by depositing an oxide layer having a thickness of less than 10 kW using a natural oxidation method.

In addition, in the method of manufacturing a spin valve magnetoresistive thin film according to the present invention, when the oxide layer is formed in the main chamber, the target in the main chamber is oxidized to subsequently remove oxides attached to the target during deposition of the magnetic layer. We found a problem. Therefore, in the manufacturing method according to the present invention, after depositing the magnetic layer in the main chamber, the sample is moved to a load lock chamber or a separate oxidation chamber, and the chamber atmosphere is changed to oxygen, oxygen / nitrogen or oxygen / inert gas atmosphere. An oxide layer was prepared by oxidizing the surface of the second ferromagnetic layer partially deposited for 1 minute to 20 hours while maintaining a 100 Torr partial pressure. In the deposition of the nano oxide layer, the low oxygen partial pressure must be oxidized for a long time, and the higher the partial pressure, the less time required for oxidation. At low oxygen partial pressure of less than 1 mTorr, the oxidation time should be longer than 20 hours, and at partial pressures of 100 Torr or more, the time required for oxidation decreases to less than 1 minute, making it difficult to form a uniform oxide layer. At this time, when the oxygen partial pressure is set to 5 to 200 mTorr, the deposition time of the oxide layer is more preferably several minutes to 5 hours, which is more preferable. The oxide layer can be formed under a pure oxygen atmosphere, and can be oxidized in an oxygen / nitrogen atmosphere in which nitrogen and oxygen are mixed at an appropriate ratio, or in an oxygen / inert gas atmosphere in which oxygen and an inert gas are mixed at an appropriate ratio. In this case, the oxide layer is uniformed by nitrogen or inert gas, which is advantageous for the production of the oxide layer. After the oxide layer is prepared, the sample is moved back to the main chamber to deposit the remaining magnetic and protective layers.

In addition, in the method of manufacturing a spin valve magnetoresistive thin film according to the present invention, a sample prepared by inserting an oxide layer in the middle of a magnetic layer in the middle has a very low effect of the oxide layer, so that the deposited sample is used with a vacuum and a magnetic field applied heat treatment furnace. By performing heat treatment above the blocking temperature, a uniform oxide layer can be produced. It is difficult to expect an increase in the magnetoresistance ratio due to the specular effect because the interface of the oxide layer is not uniform before heat treatment, but after heat treatment, an oxide layer is uniformly formed by heat treatment, and an antiferromagnetic layer due to heat generated during device manufacturing In addition to preventing the diffusion of, the magnetoresistance ratio was also increased by the specular effect. In this heat treatment, the top- or bottom-type spin valve magnetoresistive thin film in which all the structures are laminated is subjected to vacuum at 5 × 10 ⁻⁴ to 1 × 10 ⁻⁸ Torr for 5 minutes in a temperature range of 50 to 450 ° C. It is preferable to heat-treat in a magnetic field for ˜ 10 hours. At this time, the heat treatment may be performed while controlling the temperature within the above range in the temperature increase rate of 0.1 ~ 200 ℃ / second and the cooling rate 0.1 ~ 200 ℃ / second. At this time, when the temperature is 0.1 ° C / sec or less, the interface of the oxide layer is not sag, which is disadvantageous. When the temperature is 200 ° C / sec or more, it is difficult to control the temperature increase rate of the heat treatment furnace.

As the material of the antiferromagnetic layer usable in the present invention, both Mn-based metal and oxide antiferromagnetic materials may be used. Preferably, the Mn-based metal is much superior in thermal properties due to the insertion of the oxide layer.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited by Examples.

Example 1

Using a substrate deposited with a thickness of 1500 1500 SiO ₂ on Si, Ta (50Å) / NiFe (45Å) / CoFe (15Å) / Cu (26Å) / CoFe (20Å) / NOL (Nano Oxide Layer) / CoFe (20Å) ) / FeMn (80 kV) / Ta (50 kPa) columnar spin valve magnetoresistive thin films were prepared by the direct current magnetron method. Specifically, the base pressure of the chamber was maintained at 2 × 10 ⁻⁸ Torr or less, and the atmosphere of the chamber was kept as clean as possible to prevent the incorporation of impurities into the sample. The spattering partial pressure was 1 to 2 mTorr, the spattering power was 20 to 100 W, and the deposition rate was maintained at 0.5 to 2 mW / sec as the deposition conditions of the magnetic layer and the nonmagnetic layer. Oxidation layer formation was not carried out in the main chamber to prevent oxidation of the target in the main chamber, and the sample was moved to the load lock chamber to give an oxygen partial pressure of 50 mTorr for 20 minutes of natural oxidation. Thereafter, the sample was moved back to the main chamber, and the remaining layer of the fixed layer was deposited to prepare a spin valve magnetoresistive thin film. In order to see the effect of the oxide layer, the prepared sample was heat-treated to 250 ° C. by applying a magnetic field in 2 × 10 ⁻⁶ Torr vacuum. After depositing the sample and the heat-treated sample at room temperature by measuring the RH curve by a four-terminal probe method, the magnetoresistance ratio is shown in FIG. 2 according to the heat treatment temperature. As can be seen in FIG. 2, the magnetoresistance ratio increased as the heat treatment temperature increased.

Example 2

Samples prepared in the same manner as in Example 1 were heat treated to 250 ° C., and then M-H curves were measured to obtain exchange bias sizes. Thereafter, the change of the size of the exchange bias according to the heat treatment temperature is shown in FIG. 3.

Example 3

Using a substrate on which SiO ₂ was deposited to a thickness of 1500Å on Si, Ta (50Å) / NiFe (20Å) / FeMn (80Å) / CoFe (20Å) / NOL / CoFe (20Å) / Cu (26Å) / NiFe (45Å) ) / CoFe (15Å) / Ta (50Å) bottom-bottom spin valve magnetoresistive thin films were prepared by the direct current magnetron method. In the preparation of the sample, the same conditions as in Example 1 were used. After the sample was prepared, the magnetic field was applied in vacuum to heat the specimen to 300 ° C., and then the RH curve was measured at room temperature to obtain the magnetoresistance ratio. The magnetoresistance ratio according to the heat treatment temperature is shown in FIG. 4.

Example 4

After the samples prepared in the same manner as in Example 3 were each heat-treated to 300 ℃, the M-H curve was measured to determine the size of the exchange bias. The exchange bias size according to the heat treatment temperature is shown in FIG. 5.

Example 5

Using a substrate deposited with a thickness of 1500 1500 SiO ₂ on Si, Ta (50Å) / NiFe (20Å) / IrMn (80Å) / CoFe (20Å) / NOL / CoFe (20Å) / Cu (26Å) / NiFe (45Å) ) / CoFe (15Å) / Ta (50Å) bottom-bottom spin valve magnetoresistive thin films were prepared by the direct current magnetron method. Spin valve magnetoresistive thin films were prepared using IrMn antiferromagnetic layers instead of FeMn antiferromagnetic layers. Preparation of the sample used the same conditions as Example 1. After sample preparation, the heat treatment temperature was increased to 400 ° C, unlike the FeMn-based spin valve magnetoresistive thin film. The change in the magnetoresistance ratio according to the heat treatment temperature is shown in FIG. 6.

Example 6

After the bottom-type spin valve including the NOL prepared in Example 3 was heat treated at 300 ° C., and the magnetoresistance ratio was maintained at 9.5%, the compositional gradient in the specimen thickness direction was examined to examine the structural stability of the multilayer thin film. Secondary ion mass spectrometry was performed to show the sputter depth side composition distribution of the Mn element in FIG. 7. As can be seen in Figure 7, it can be seen that the concentration of Mn rapidly increases toward FeMn and then rapidly decreases toward CoFe / Cu / CoFe around the CoFe / NOL / CoFe layer including NOL. This indicates that NOL maintains spin dependent scattering at the CoFe / Cu / CoFe / NiFe interface, which prevents the diffusion of Mn and influences the magnetoresistance ratio characteristics.

Comparative Example 1

Using a substrate in which SiO ₂ was deposited to a thickness of 1500 Å in Si, Ta (50 Å) / NiFe (45 Å) / CoFe (15 Å) / Cu (26 Å) / CoFe (40 Å) / FeMn (80 Å) / A Ta (50 kPa) columnar spin valve magnetoresistive thin film was prepared by a direct current magnetron method. Samples were prepared under the same conditions as in Example 1 except for the oxidation conditions. In addition, the heat treatment conditions were the same as that of Example 1. Thus, the change of the magnetoresistance ratio according to the heat processing temperature is shown in FIG. As can be seen in Figure 2, the magnetoresistance ratio according to the heat treatment temperature of the top spin valve magnetoresistive thin film according to Example 1 of the present invention was higher than the top spin valve magnetoresistive thin film according to Comparative Example 1.

Comparative Example 2

Using a substrate on which SiO ₂ was deposited to a thickness of 1500 Å in Si, Ta (50 Å) / NiFe (20 Å) / FeMn (80 Å) / CoFe (40 Å) / Cu (26 Å) / CoFe (15 Å) / NiFe (45 kV) / Ta (50 kV) bottom spin type magnetoresistive thin films were prepared by a direct current magnetron method. Preparation of the samples was carried out using the same conditions as in Example 1 without oxidation. The change of the magnetic anisotropy intensity of the exchange according to the heat treatment temperature of the sample thus prepared is shown in FIG. 4. As can be seen in Figure 4, when the heat treatment temperature is about 150 Pa or more, the bottom resistance spin valve according to the heat treatment temperature of the bottom-type spin valve magnetoresistive thin film according to the third embodiment of the present invention the bottom-type spin valve according to Comparative Example 2 It appeared higher than the magnetoresistive thin film.

Comparative Example 3

Using a substrate in which SiO ₂ was deposited to a thickness of 1500 Å in Si, Ta (50 Å) / NiFe (20 Å) / IrMn (80 Å) / CoFe (40 Å) / Cu (26 Å) / NiFe (45 Å) / CoFe (15Å) / Ta (50Å) bottom spin type magnetoresistive thin films were prepared by a direct current magnetron method. In the spin valve magnetoresistive thin film of this comparative example, an IrMn antiferromagnetic layer was used instead of the FeMn antiferromagnetic layer. Preparation of the sample was carried out under the same conditions as in Example 1. After the sample preparation, the heat treatment temperature was increased by 350 kPa, unlike the FeMn-based spin valve magnetoresistive thin film. The change in the magnetoresistance ratio according to the heat treatment temperature of the sample thus prepared is shown in FIG. 6. As can be seen in Figure 6, the magnetoresistance ratio according to the heat treatment temperature of the bottom type spin valve magnetoresistive thin film according to Example 5 of the present invention was higher than the bottom type spin valve magnetoresistive thin film according to Comparative Example 3.

Example 7

Using a substrate on which SiO ₂ was deposited to a thickness of 1500Å on Si, Ta (50Å) / NiFe (20Å) / IrMn (80Å) / CoFe (20Å) / NOL / CoFe (20Å) / Cu (26Å) / NiFe (45Å) ) / CoFe (15Å) / Ta (50Å) bottom-bottom spin valve magnetoresistive thin films were prepared by the direct current magnetron method. At this time, the partial pressure ratio of the two gases of nitrogen gas (N ₂ ) and oxygen gas (O ₂ ) was changed while maintaining the chamber atmosphere at a total gas pressure of 50 mTorr in the natural oxidation method for producing NOL. The specimens were heat-treated in a magnetic field for 30 minutes at a temperature of 250 ° C. in a 5 × 10 ⁻⁶ Torr vacuum, and then subjected to furnace cooling to measure a magnetoresistance ratio. 8 shows the change in the magnetoresistance ratio of the bottom type spin valve according to the partial pressure of nitrogen and oxygen gas through the experimental procedure. It can be seen that the natural resistance of oxygen to nitrogen in the ratio of 9: 1 to 5: 5 increases the magnetoresistance ratio even more than the natural oxidation condition only oxygen. Optimum conditions were 7: 3 for oxygen to nitrogen. This role of nitrogen is due to the more homogeneous surface oxidation, making the smoother smoother while reducing the roughness of the interface between the NOL layer and the CoFe layer for specular reflection, thereby increasing specular reflectivity.

Example 8

Using a substrate deposited with a thickness of 1500 1500 SiO ₂ on Si, Ta (50Å) / NiFe (20Å) / IrMn (80Å) / CoFe (20Å) / NOL / CoFe (20Å) / Cu (26Å) / NiFe (45Å) ) / CoFe (15Å) / Ta (50Å) bottom-bottom spin valve magnetoresistive thin films were prepared by the direct current magnetron method. At this time, the partial pressure ratio of the two gases, argon gas (Ar) and oxygen gas (O ₂ ), was changed while maintaining the chamber atmosphere at a total gas pressure of 50 mTorr in the natural oxidation method for producing NOL. The specimens were heat-treated in a magnetic field for 30 minutes at a temperature of 250 ° C. in a vacuum of 5 × 10 ⁻⁶ Torr, and then cooled by furnace to measure the magnetoresistance ratio. 9 shows the change in the magnetoresistance ratio of the bottom type spin valve according to the partial pressure of argon and oxygen gas through the experimental procedure. It can be seen that the natural oxidation of the oxygen to argon ratio of 9: 1 to 5: 5 is increasing the magnetoresistance ratio even more than the oxygen-only natural oxidation condition. The role of argon is also due to the more homogeneous surface oxidation, which makes the smoother smoother while reducing the roughness of the interface between the NOL and CoFe layers for specular reflection, thereby increasing specular reflectivity.

In the spin valve magnetoresistive thin film of the present invention, an oxide layer is formed on the ferromagnetic layer in contact with the antiferromagnetic layer and heat treated, thereby improving the thermal characteristics of the magnetoresistive thin film and increasing the magnetoresistance ratio. Therefore, the spin valve magnetoresistive thin film and the method of manufacturing the same according to the present invention can be applied to a large magnetoresistance magnetic head and a high output magnetic sensor for high recording density of a hard disk drive, that is, a speed, a current, a magnetic field, a position sensor, and the like.

Claims (18)

In the spin valve magnetoresistive thin film having a structure in which a buffer layer, a first ferromagnetic layer, a nonmagnetic layer, a second ferromagnetic layer, an antiferromagnetic layer, and a protective layer are sequentially deposited on a substrate, After the second ferromagnetic layer is partially formed, an oxide layer is formed, and the remaining second ferromagnetic layer is formed, thereby including an oxide layer in the middle of the second ferromagnetic layer. The oxide layer has a thickness of 5 to 20 kPa, The buffer layer is deposited to a thickness of 5 to 200 microns and has a structure that favors the formation of (111) texture, The thickness of the first ferromagnetic layer is 10 to 200 mm 3, The thickness of the nonmagnetic layer is 15 to 60 mm 3 The total thickness of the second ferromagnetic layer is 20 to 200 mm 3, The antiferromagnetic layer has a thickness of 50 to 400 mm 3. The protective layer has a thickness of 10 to 200 mm 3, A spin valve magnetoresistive thin film having a structure of a buffer layer / first ferromagnetic layer / nonmagnetic layer / second ferromagnetic layer / oxidation layer / second ferromagnetic layer / antiferromagnetic layer / protective layer. In a spin valve magnetoresistive thin film having a structure in which a buffer layer, a first ferromagnetic layer, an antiferromagnetic layer, a second ferromagnetic layer, a nonmagnetic layer, a third ferromagnetic layer, and a protective layer are sequentially deposited on a substrate, After the second ferromagnetic layer is partially formed, an oxide layer is formed, and the remaining second ferromagnetic layer is formed, thereby including an oxide layer in the middle of the second ferromagnetic layer. The oxide layer has a thickness of 5 to 20 kPa, The buffer layer is deposited to a thickness of 5 to 200 microns and has a structure that favors the formation of (111) texture, The thickness of the first ferromagnetic layer is 10 to 200 mm 3, The antiferromagnetic layer has a thickness of 50 to 400 mm 3. The total thickness of the second ferromagnetic layer is 20 to 200 mm 3, The thickness of the nonmagnetic layer is 15 to 60 mm 3, The thickness of the third ferromagnetic layer is 10 to 200 mm 3, The protective layer has a thickness of 10 to 200 mm 3, A spin valve magnetoresistive thin film having a structure of a buffer layer / first ferromagnetic layer / antiferromagnetic layer / second ferromagnetic layer / oxidation layer / second ferromagnetic layer / nonmagnetic layer / third ferromagnetic layer / protective layer. delete The spin valve magnetoresistive thin film according to claim 1 or 2, wherein the substrate is an oxide-based Si substrate, an oxide- or nitride-treated Si substrate, or a glass substrate. The spin valve magnetoresistive thin film according to claim 1 or 2, wherein the buffer layer is formed by depositing Ta, Cu, Au, Al, Pd or Pt. The spin valve magnetoresistive thin film according to claim 1 or 2, wherein the first ferromagnetic layer is formed by depositing NiFe, CoFe, or NiFe / CoFe. The spin valve magnetoresistive thin film according to claim 1 or 2, wherein the second ferromagnetic layer is formed by depositing CoFe or NiFe. The spin valve magnetoresistive thin film of claim 2, wherein the third ferromagnetic layer is formed by depositing NiFe, CoFe, or NiFe / CoFe. The spin valve magnetoresistive thin film according to claim 1 or 2, wherein the nonmagnetic layer is formed by depositing Cu. The spin valve magnetoresistive thin film according to claim 1 or 2, wherein the antiferromagnetic layer is formed by depositing FeMn, IrMn, PtMn, or PdPtMn. The spin valve magnetoresistive thin film according to claim 1 or 2, wherein the protective layer is formed by depositing Ta, Cu, oxide or nitride. Depositing Ta, Cu, Au, Al, Pd or Pt on the substrate to a thickness of 5 to 200 microns to form a buffer layer having a structure that favors the formation of the (111) texture, Forming a first ferromagnetic layer by depositing NiFe, CoFe, or NiFe / CoFe on the buffer layer to a thickness of about 10 to about 200 microseconds; Depositing Cu on a ferromagnetic layer adjacent to the buffer layer to a thickness of 15 to 60 Å to form a nonmagnetic layer, Depositing a portion of a ferromagnetic layer in forming a second ferromagnetic layer by depositing CoFe or NiFe with a total thickness of 20 to 200Å over the nonmagnetic layer, Oxidizing the surface of the partially deposited ferromagnetic layer to form an oxide layer, and then depositing the remaining ferromagnetic layer with CoFe or NiFe to form an oxide layer in the middle of the second ferromagnetic layer, Depositing FeMn, IrMn, PtMn or PdPtMn on the ferromagnetic layer to a thickness of 50 to 400 GPa to form an antiferromagnetic layer, and Forming a protective layer by depositing Ta, Cu, oxide or nitride on the ferromagnetic layer in a thickness of 10 to 200 microseconds, the buffer layer / first ferromagnetic layer / nonmagnetic layer / second ferromagnetic layer / oxide layer / second ferromagnetic A method of manufacturing a spin valve magnetoresistive thin film having a structure in which layers / antiferromagnetic layers / protective layers are sequentially deposited. Depositing Ta, Cu, Au, Al, Pd or Pt on a substrate to a thickness of 5 to 200 microns to form a buffer layer having a structure that favors (111) texture formation, Forming a first ferromagnetic layer by depositing NiFe, CoFe, or NiFe / CoFe on the buffer layer to a thickness of 10 to 200Å; Forming an antiferromagnetic layer by depositing FeMn, IrMn, PtMn, or PdPtMn to a thickness of 50 to 400 위에 on the ferromagnetic layer, Depositing a portion of a ferromagnetic layer in forming a second ferromagnetic layer by depositing CoFe or NiFe with a total thickness of 20 to 200 ~ over the antiferromagnetic layer, Oxidizing the surface of the partially deposited ferromagnetic layer to form an oxide layer, and then depositing the remaining ferromagnetic layer with CoFe or NiFe to form an oxide layer in the middle of the second ferromagnetic layer, Depositing Cu on the ferromagnetic layer to a thickness of 15 to 60 μm to form a nonmagnetic layer, Forming a third ferromagnetic layer by depositing NiFe, CoFe, or NiFe / CoFe on the nonmagnetic layer to a thickness of 10˜200 μs, and Forming a protective layer by depositing Ta, Cu, oxide or nitride on the ferromagnetic layer in a thickness of 10 to 200 Å. A method of manufacturing a spin valve magnetoresistive thin film having a structure of a layer / nonmagnetic layer / third ferromagnetic layer / protective layer. The method according to claim 12 or 13, wherein the oxide layer is formed using a natural oxidation method. The method of claim 12 or 13, wherein the oxide layer is formed in a load lock chamber or a separate oxidation chamber other than the main chamber. The oxygen / nitrogen mixed gas of claim 12 or 13, wherein pure oxygen, oxygen and nitrogen are mixed at a partial pressure ratio of 9: 1 to 5: 5, or an oxygen and inert gas to a partial pressure ratio of 9: 1 to 5. : Method to form by adjusting partial pressure to 1 mTorr ~ 100 Torr in the oxygen / inert gas mixed gas atmosphere mixed with 5. The method according to claim 12 or 13, wherein the tower- or bottom-type spin valve magnetoresistive thin film which has completed the lamination of all structures including the oxide layer is subjected to a vacuum of 5 x 10 ^-4 to 1 x 10 ^-8 Torr at 50 to 450 ° C. In a temperature range of 5 minutes to 10 hours, further comprising heat-treating in a magnetic field. 18. The method of claim 17, further comprising controlling the treatment temperature to a temperature increase rate of 0.1 to 200 ° C / sec and a cooling rate of 0.1 to 200 ° C / sec.