JP2008226987A - Method and device for manufacturing magnetoresistive element and method and device for manufacturing magnetic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for manufacturing a magnetoresistive element and a method and device for manufacturing a magnetic device improving the reproducibility of a magnetoresistance effect. <P>SOLUTION: In the device for manufacturing the magnetic device, a leakage magnetic field is formed on the surface of a target T by using a magnetic circuit 37, and the intensity of a horizontal magnetic field on the surface of the target T is set in 2,000 (Oe) to 3,000 (Oe). When a tunnel barrier layer is laminated on a substrate 11, the target T mainly comprising magnesium oxide is sputtered under the horizontal magnetic field of 2,000 (Oe) to 3,000 (Oe) on the surface. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetoresistive element manufacturing method, a magnetic device manufacturing method, a magnetoresistive element manufacturing apparatus, and a magnetic device manufacturing apparatus.

Magnetic devices such as MRAM (Magnetoresistive Random Access Memory) and HDD (Hard Disk Drive) use magnetoresistive elements that change element resistance in accordance with a magnetic field. As a magnetoresistive element, a TMR element that obtains a high magnetoresistance change rate (hereinafter simply referred to as MR ratio) of several tens of percent or more by using a tunneling magnetoresistive effect (TMR effect: Tunneling Magnetoresistive) is known.

  The TMR element includes a pinned magnetic layer that strongly fixes the direction of spontaneous magnetization, a free magnetic layer that allows rotation of the direction of spontaneous magnetization, and a tunnel barrier layer that is sandwiched between the pinned magnetic layer and the free magnetic layer And have. In the TMR element, the relative magnetization directions in the two magnetic layers are controlled by an input signal, and the element resistance is largely changed depending on whether or not the relative magnetization directions are the same. The TMR element stores the magnetization direction according to the input signal as memory information, or outputs the output voltage according to the input magnetic field as memory information.

With the rapid spread of mobile terminals and electronic devices, TMR elements are required to have higher integration and higher speed, and have a high MR ratio for detecting weak signals and low for increasing the processing speed. Element resistance is required. In the TMR element, a proposal has been made to use a magnesium oxide layer (MgO layer) as a tunnel barrier layer as a means for achieving both a high MR ratio and a low element resistance (for example, Patent Document 1). The MgO layer is preferentially oriented in the (100) plane of the crystal orientation of a film obtained from a material that easily takes a regular atomic arrangement, and the higher the degree of orientation, the better the straightness of electrons improves. TMR effect is developed.
JP 2007-48972 A

  As a method for producing the MgO layer, a magnetron sputtering method is known in which an MgO layer is formed by sputtering using a target mainly composed of MgO. In the magnetron sputtering method, a magnetic circuit is disposed on the back surface of a target, and high-density plasma is generated on the surface of the target by a magnetic field of several hundreds (Oe) leaking from the surface of the target. Then, ions of the sputtering gas are accelerated and incident on the target, and MgO particles sputtered from the target are attached to the surface of the substrate, thereby depositing a high-purity MgO layer on the surface of the substrate.

  However, in the manufacturing method of the MgO layer using the magnetron sputtering method, conventionally, the relationship between the orientation of the MgO layer and various film forming parameters has not been studied. Therefore, in the magnetron sputtering method, when the size of the manufacturing apparatus is changed in accordance with the size of the substrate, there is a problem that the reproducibility of the orientation of the MgO layer and hence the reproducibility of the magnetoresistance effect cannot be obtained sufficiently. It was.

  The present invention has been made to solve the above problems, and its purpose is to manufacture a magnetoresistive element, a magnetic device manufacturing method, and a magnetoresistive element manufactured with improved reproducibility of the magnetoresistive effect. An apparatus and an apparatus for manufacturing a magnetoresistive device are provided.

  The inventors examined the relationship between the orientation of the MgO layer and various film formation parameters. The (100) plane orientation of the MgO layer is the power applied to the target (hereinafter simply referred to as sputtering power). It has been found that the strength decreases as the pressure decreases, and the strength increases as the pressure during sputtering (hereinafter simply referred to as sputtering pressure) decreases.

  FIG. 6 is an X-ray diffraction spectrum of the MgO layer formed by using the magnetron sputtering method, and the X-ray diffraction intensities of sputtering power of 350 (W) to 100 (W) are equally spaced along the vertical axis direction. Shown separated by. FIG. 7 is an X-ray diffraction spectrum of an MgO layer formed by using a magnetron sputtering method, and the X-ray diffraction intensities at a sputtering gas flow rate of 5 (sccm) to 100 (sccm) are respectively along the vertical axis direction. Shown at equal intervals.

  6 and 7, the (200) plane of the MgO layer is observed at a position where the diffraction angle 2θ is around 40 °. The (200) plane orientation of the MgO layer becomes stronger as the sputtering power is changed from 350 (W) to 100 (W). It can also be seen that the (200) plane orientation of the MgO layer becomes stronger as the flow rate of the sputtering gas is changed from 100 (sccm) to 5 (sccm), that is, as the sputtering pressure is lowered.

  On the other hand, if the sputtering pressure is excessively lowered, generally, the plasma potential is increased and the incident energy of the sputtered particles is increased. Sputtered particles with high incident energy lower the regularity of the atomic arrangement of the MgO layer and weaken the (100) plane orientation. Further, if the sputtering pressure or sputtering power is excessively lowered, the plasma density is lowered, resulting in instability of discharge and film formation failure. Therefore, the reproducibility of (100) plane orientation cannot be sufficiently obtained only by changing the sputtering pressure and sputtering power.

  Thus, if a stable discharge can be provided without increasing the plasma potential under the conditions of lower sputtering pressure and lower sputtering power, sufficient reproducibility can be given to (100) plane orientation. it is conceivable that.

  Generally, in the magnetron sputtering method, the strength of the horizontal magnetic field leaking from the surface of the target is set to several hundreds (Oe). The present inventors focused on the intensity of the horizontal magnetic field based on the relationship between the (100) plane orientation of the MgO layer and the film formation parameters, and significantly increased the horizontal magnetic field on the surface of the MgO target. It has been found that the reproducibility of the plane orientation can be improved.

  FIG. 8 shows the lower limit sputtering pressure that can maintain the discharge with respect to the horizontal magnetic field leaking from the surface of the target. FIG. 9 shows a lower limit sputtering voltage at which discharge can be maintained for each horizontal magnetic field leaking from the surface of the target using a direct current magnetron sputtering method.

  In FIG. 8 and FIG. 9, the lower limit value of the sputtering pressure can be lowered and the lower limit value of the sputtering voltage can be lowered as the horizontal magnetic field leaking from the surface of the target is increased. That is, it can be seen that by increasing the horizontal magnetic field, the lower limit value of the sputtering pressure can be lowered and the lower limit value of the sputtering power can be lowered. In other words, it can be seen that by increasing the horizontal magnetic field, the sputtering conditions can be extended toward the region where the (100) plane orientation becomes stronger.

In order to solve the above problem, the invention described in claim 1 includes a step of forming a first magnetic layer on a substrate, a step of laminating a magnesium oxide layer on the first magnetic layer, and a step of forming the magnesium oxide layer. A step of laminating a second magnetic layer, wherein the step of laminating the magnesium oxide layer is performed on a surface of a target mainly composed of magnesium oxide from 2000 (Oe) to The gist is to sputter the target by forming a horizontal magnetic field of 3000 (Oe).

  According to the method of manufacturing a magnetoresistive element according to claim 1, the lower limit value of the sputtering pressure can be lowered by an amount corresponding to the horizontal magnetic field of 2000 (Oe) or more. The lower limit value of electric power can be lowered. Therefore, the sputtering conditions of the MgO layer can be expanded toward the region where the (100) plane orientation of the MgO layer becomes strong. Further, unnecessary expansion of the magnetic circuit can be suppressed by suppressing the horizontal magnetic field to 3000 (Oe) or less. Therefore, the sputtering conditions can be extended toward the region where the (100) plane orientation of the MgO layer becomes strong, and the reproducibility of the magnetoresistive effect of the magnetoresistive element using the MgO layer can be improved.

  Invention of Claim 2 is a manufacturing method of the magnetoresistive element of Claim 1, Comprising: In the process of laminating | stacking the said magnesium oxide, the horizontal magnetic field which leaks from the surface of the said target is 2000 on the surface of the said target. The gist is to change the distance between the surface of the target and the magnetic circuit so as to be (Oe) to 3000 (Oe).

  According to this magnetoresistive element manufacturing method, a horizontal magnetic field of 2000 (Oe) to 3000 (Oe) can be formed on the surface of the target only by changing the distance between the surface of the target and the magnetic circuit. . Therefore, the reproducibility of the magnetoresistance effect can be improved by a simple method.

  In order to solve the above problem, the invention described in claim 3 is a method of manufacturing a magnetic device including a magnetoresistive element, wherein the magnetoresistive element is a method of manufacturing a magnetoresistive element according to claim 1 or 2. The gist is to manufacture using

  In order to solve the above problem, the invention according to claim 4 includes a transport unit that transports a substrate, a first film forming unit that is connected to the transport unit and forms a first magnetic layer on the substrate, and A second film forming unit connected to the transport unit and stacking a magnesium oxide layer on the first magnetic layer, and a third film forming unit connected to the transport unit and stacking a second magnetic layer on the magnesium oxide layer The second film-forming unit includes a target mainly composed of magnesium oxide, and a horizontal magnetic field of 2000 (Oe) to 3000 (Oe) on the surface of the target. And a magnetic circuit for forming the above.

  According to the magnetoresistive element manufacturing apparatus of claim 4, the lower limit value of the sputtering pressure can be lowered by the amount of the second film forming unit by setting the horizontal magnetic field to 2000 (Oe) or more. In the pressure region, the lower limit value of the sputtering power can be lowered. Therefore, the sputtering conditions of the MgO layer can be expanded toward the region where the (100) plane orientation of the MgO layer becomes strong. In addition, since the horizontal magnetic field is suppressed to 3000 (Oe) or less, unnecessary expansion of the magnetic circuit can be suppressed, and expansion of the device size can be suppressed. Therefore, the sputtering conditions can be extended toward the region where the (100) plane orientation of the MgO layer becomes strong, and the reproducibility of the magnetoresistive effect of the magnetoresistive element using the MgO layer can be improved.

  In order to solve the above problem, an invention according to claim 5 is an apparatus for manufacturing a magnetic device including a magnetoresistive element, and the magnetoresistive element according to claim 4 is used to manufacture the magnetoresistive element. The gist is that a manufacturing apparatus is provided.

As described above, according to the present invention, a magnetoresistive element manufacturing method, a magnetic device manufacturing method, a magnetoresistive element manufacturing apparatus, and a magnetic device manufacturing apparatus with improved reproducibility of the magnetoresistive effect are provided. Can do.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view illustrating the magnetoresistive element 10.
(Magnetic resistance element)
In FIG. 1, a base layer 12, a pinned magnetic layer 13, a tunnel barrier layer 14, a free magnetic layer 15, and a protective layer 16 are sequentially stacked on a substrate 11 of the magnetoresistive element 10 from the substrate 11 side.

  The underlayer 12 is a buffer layer that alleviates surface roughness of the substrate 11 and facilitates connection with the upper layer (pinned magnetic layer 13). The underlayer 12 functions as a seed layer and defines the crystal orientation of the upper layer. The underlayer 12 is not limited to a single layer structure, and may have a two-layer structure including a buffer layer and a seed layer. As this underlayer 12, for example, Ta, Ti, W, Cr, or an alloy thereof can be used.

  The pinned magnetic layer 13 includes a pinning layer 13a stacked on the underlayer 12 and a pinned layer 13b stacked on the pinning layer 13a. The pinning layer 13a and the pinned layer 13b are an antiferromagnetic layer and a ferromagnetic layer, respectively, and the magnetization direction of the pinned layer 13b is fixed in one direction by the interaction with the pinning layer 13a. The pinned layer 13b is not limited to a single layer structure, but may be a known laminated ferrimagnetic structure including a ferromagnetic layer / magnetic coupling layer / ferromagnetic layer. As the pinning layer 13a, IrMn, PtMn, and PdPtMn can be used. NiFe, CoFe, CoFeB can be used for the pinned layer 13b.

  The tunnel barrier layer 14 is an insulating film containing magnesium oxide (MgO) as a main component and has a film thickness that allows a tunnel current to flow in the thickness direction. The resistance value of the tunnel barrier layer 14 varies depending on whether the relative directions of the spontaneous magnetization of the pinned magnetic layer 13 and the free magnetization of the free magnetic layer 15 are parallel or antiparallel. The tunnel barrier layer 14 is manufactured using the following magnetic device manufacturing apparatus.

  The free magnetic layer 15 is a ferromagnetic layer having a coercive force that makes the direction of spontaneous magnetization rotatable. The free magnetic layer 15 rotates the direction of spontaneous magnetization, and has spontaneous magnetization parallel to the direction of spontaneous magnetization of the pinned magnetic layer 13 or antiparallel spontaneous magnetization. The free magnetic layer 15 can be a single layer structure of CoFe or a stacked structure in which NiFe is stacked on CoFe.

  The protective layer 16 is a barrier layer against the outside air, and forms a passive state having a high barrier property to protect the spontaneous magnetization of the free magnetic layer 15. The protective layer 16 is a buffer layer that alleviates the surface roughness of the free magnetic layer 15 and smoothly connects the peripheral circuit and the magnetoresistive element 10. Ta, Ti, W, Cr, or alloys thereof can be used for the protective layer 16.

In the present embodiment, the pinned magnetic layer 13, the tunnel barrier layer 14, and the free magnetic layer 15 constitute a first magnetic layer, a magnesium oxide layer, and a second magnetic layer, respectively.
(Magnetic device manufacturing equipment)
Next, a magnetoresistive element manufacturing apparatus 20 constituting a magnetic device manufacturing apparatus will be described with reference to FIGS. FIG. 2 is a plan view schematically showing the magnetoresistive element manufacturing apparatus 20, and FIG. 3 is a side sectional view showing the magnesium oxide chamber 24.

In FIG. 2, the magnetoresistive element manufacturing apparatus 20 includes a transfer chamber 21 as a transfer unit. A pair of load lock chambers (hereinafter simply referred to as LL chambers) 22, a first lower layer chamber 23A, a second lower layer chamber 23B, and a third lower layer chamber 23C are connected to the transfer chamber 21 so as to communicate with each other. Further, a magnesium oxide chamber (hereinafter simply referred to as MgO chamber) 24, a first upper layer chamber 25A, and a second upper layer chamber 25B are connected to the transfer chamber 21 so as to communicate with each other.

  The transfer chamber 21 has a bottomed cylindrical chamber main body 21a formed in a regular octagonal prism shape, and an internal space (hereinafter simply referred to as a transfer chamber 21s) is formed inside the chamber main body 21a. . The upper side of the chamber body 21a is covered with a chamber lid (not shown) to maintain the vacuum state of the transfer chamber 21s. The transfer chamber 21 is equipped with a transfer robot 21b in the transfer chamber 21s. The transfer robot 21b carries the substrate 11 accommodated in the LL chamber 22 into the transfer chamber 21s, and the first lower layer chamber 23A, the second lower layer chamber 23B, the third lower layer chamber 23C, the MgO chamber 24, and the first upper layer chamber 25A. Then, the substrate 11 is transferred in the order of the second upper layer chamber 25B. Then, the transfer robot 21b carries the substrate 11 after the film formation process from the second upper layer chamber 25B to the LL chamber 22.

  The LL chamber 22 has a stage for accommodating a plurality of substrates 11 and accommodates a plurality of substrates 11 transferred from a transfer machine (not shown). The LL chamber 22 depressurizes the chamber to a predetermined pressure so that the substrate 11 can be carried into the transfer chamber 21. Further, the LL chamber 22 accommodates the substrate 11 after the film formation process, and allows the inside of the chamber to be released to the atmosphere so that it can be carried out.

  The first lower layer chamber 23A is a sputtering chamber that sputters the surface of the substrate 11, and cleans the surface of the substrate 11 by sputtering. The second lower chamber 23B and the third lower chamber 23C are sputter chambers equipped with targets for laminating the base layer 12 and the pinned magnetic layer 13 (pinning layer 13a and pinned layer 13b), respectively. Laminate corresponding films. In the second lower layer chamber 23B, for example, a Ta target and a PtMn target are mounted, and a Ta layer as the base layer 12 and a PtMn layer as the pinning layer 13a are stacked. In the third lower layer chamber 23C, for example, a CoFe target, a Ru target, and a CoFeB target are mounted, and a CoFe layer / Ru layer / CoFeB layer as the pinned layer 13b is stacked.

  The MgO chamber 24 is a magnetron sputtering type sputtering chamber on which a target mainly composed of MgO is mounted, and the tunnel barrier layer 14 mainly composed of MgO is formed.

In FIG. 3, the MgO chamber 24 has a chamber main body 31 connected to the transfer chamber 21, and an internal space (hereinafter simply referred to as a sputtering chamber 31 </ b> S) that can communicate with the transfer chamber 21 s inside the chamber main body 31. have. The chamber body 31 has a gas supply unit 32 that communicates with the sputtering chamber 31S via the supply pipe IL. The gas supply unit 32 adjusts argon (Ar) as a sputtering gas or a mixed gas of Ar and oxygen (O ₂ ) to a predetermined flow rate and supplies the mixed gas to the sputtering chamber 31S.

The sputter chamber 31S is connected to an exhaust system 33 including a turbo molecular pump and a dry pump via an exhaust pipe OL. The exhaust system 33 exhausts Ar or a mixed gas of Ar and O ₂ supplied to the sputtering chamber 31S so that the pressure value in the sputtering chamber 31S can be reduced to 10 ⁻³ (Pa).

A stage 34 for placing the substrate 11 is disposed in the sputtering chamber 31S. The stage 34 places the substrate 11 carried in from the transfer chamber 21, and positions and fixes the substrate 11 at a predetermined position in the sputtering chamber 31S. On the inner wall of the sputter chamber 31 </ b> S, a bonding plate 35 formed in a substantially cylindrical shape is disposed so as to surround the upper side of the stage 34. Bokura board 35
Prevents sputter particles from adhering to the inner wall of the sputter chamber 31S when sputter deposition is performed in the sputter chamber 31S.

  A target T formed in a disk shape is disposed immediately above the stage 34. The target T is a target mainly composed of MgO. A target electrode 36 is disposed on the upper side of the target T. The target electrode 36 makes the target T face the substrate 11 and holds the distance between the target T and the substrate 11 at a predetermined distance. The target electrode 36 is connected to the external power supply FG and supplies a predetermined high frequency power from the external power supply FG to the target T. When the external power supply FG supplies high frequency power, the target electrode 36 generates plasma in the sputtering chamber 31S, and functions as a negative potential, that is, a cathode, to sputter the target T with respect to the plasma space.

  A magnetic circuit 37 is disposed above the target electrode 36. The magnetic circuit 37 has a magnet plate 38, and an outer magnet M1 and an inner magnet M2 are mounted below the magnet plate 38.

  The magnet plate 38 is formed in a disk shape, and is arranged so that the center thereof faces the center of the target T. The magnet plate 38 is drivingly connected to a drive shaft of a rotary motor M provided in the magnetic circuit 37, and rotates when the rotary motor M is driven with the center of the magnet plate 38 as a rotation center.

  The outer magnet M1 and the inner magnet M2 are neodymium-iron-boron magnets, respectively, are formed in a ring shape that is eccentric with respect to the rotation axis of the magnet plate 38, and the outer magnet M1 surrounds the inner magnet M2. It is arranged to surround. The magnetic pole on the lower side (target T side) of the outer magnet M1 and the magnetic pole on the lower side (target T side) of the inner magnet M2 are separated upward from the surface of the target T by a predetermined distance (for example, 10 (mm)). Each having a reverse polarity. For example, the lower magnetic pole of the outer magnet M1 is the S pole, and the lower magnetic pole of the inner magnet M2 is the N pole. The lines of magnetic force coming out from the lower magnetic pole of the inner magnet M2 enter the sputtering chamber 31S through the target T, bend near the surface of the target T, and enter the lower magnetic pole of the outer magnet M1.

  That is, the outer magnet M1 and the inner magnet M2 form a leakage magnetic field on the surface of the target T, and form a magnetic field along the surface direction of the target T (hereinafter simply referred to as a horizontal magnetic field) on the surface of the target T. The horizontal magnetic field formed by the outer magnet M1 and the inner magnet M2 is scanned over the entire surface of the target T when the rotary motor M rotates. The horizontal magnetic field formed by the outer magnet M1 and the inner magnet M2 increases the plasma density by capturing the plasma near the surface of the target T when the target electrode 36 generates plasma in the sputtering chamber 31S.

  At this time, the outer magnet M1 and the inner magnet M2 form a leakage magnetic field on the surface of the target T that has a horizontal magnetic field strength of 2000 (Oe) or more and 3000 (Oe) or less. For example, the inner magnet M2 and the outer magnet M1 are each a distance between the lower magnetic pole of the outer magnet M1 and the surface of the target T, or between the lower magnetic pole of the inner magnet M2 and the surface of the target T. By adjusting the distance, the strength of the horizontal magnetic field on the surface of the target T is set to 2000 (Oe) to 3000 (Oe). As a result, the MgO chamber 24 can lower the lower limit value of the sputtering pressure and lower the lower limit value of the sputtering power by an amount corresponding to the horizontal magnetic field strength of 2000 (Oe) or more. As a result, the MgO chamber 24 can expand the sputtering conditions toward a region where the (100) plane orientation of the MgO layer is strengthened.

When the substrate 11 is carried into the sputtering chamber 31S, the MgO chamber 24 has a gas supply unit 3
2 is supplied with a sputter gas at a predetermined flow rate, and the exhaust system 33 is depressurized to a predetermined pressure value by the exhaust system 33. In this state, the MgO chamber 24 drives the rotary motor M to form a horizontal magnetic field having a strength of 2000 (Oe) to 3000 (Oe) on the surface of the target T, and applies predetermined power to the external power supply FG. The target T is sputtered with high-density plasma. Sputtered MgO particles are incident on the surface of the substrate 11 to form an MgO layer on the surface of the substrate 11.

  In FIG. 2, a first upper layer chamber 25A and a second upper layer chamber 25B are sputtering chambers equipped with targets for laminating a free magnetic layer 15 and a protective layer 16, respectively, and layers corresponding to each target type are laminated. To do. In the first upper layer chamber 25A, for example, a CoFe target is mounted and a CoFe layer as the free magnetic layer 15 is stacked. In the second upper layer chamber 25B, for example, a Ta target is mounted and a Ta layer as the protective layer 16 is laminated.

  In the present embodiment, the second lower layer chamber 23B and the third lower layer chamber 23C constitute the first film forming unit, the MgO chamber 24 constitutes the second film forming unit, and the first upper layer chamber 25A and the second lower layer chamber The upper layer chamber 25B constitutes a third film forming unit.

(Magnetic device manufacturing method)
Next, a method for manufacturing a magnetic device using the manufacturing apparatus 20 will be described.
First, a plurality of substrates 11 are set in the LL chamber 22. The manufacturing apparatus 20 drives the LL chamber 22 and the transfer chamber 21 to transfer the substrate 11 of the LL chamber 22 in the order of the first lower layer chamber 23A, the second lower layer chamber 23B, and the third lower layer chamber 23C. When the manufacturing apparatus 20 carries the substrate 11 into the first lower layer chamber 23A, the manufacturing apparatus 20 drives the first lower layer chamber 23A to clean the surface of the substrate 11. In addition, when the manufacturing apparatus 20 carries the substrate 11 into the second lower layer chamber 23 </ b> B, the second lower layer chamber 23 </ b> B is driven to stack the underlayer 12 and the fixed magnetic layer 13 on the surface of the substrate 11.

  When the fixed magnetic layer 13 is stacked on the substrate 11, the manufacturing apparatus 20 unloads the substrate 11 from the third lower layer chamber 23 </ b> C and loads it into the MgO chamber 24. When the manufacturing apparatus 20 carries the substrate 11 into the MgO chamber 24, the MgO chamber 24 is driven to stack the tunnel barrier layer 14 mainly composed of MgO on the fixed magnetic layer 13. At this time, since the magnetic circuit 37 forms a horizontal magnetic field of 2000 (Oe) to 3000 (Oe) on the surface of the target T, the MgO chamber 24 can lower the lower limit value of the sputtering pressure, and The lower limit value of the sputtering power can be lowered. That is, the MgO chamber 24 can expand the sputtering conditions toward a region where the (100) plane orientation of the MgO layer is strengthened.

  When the tunnel barrier layer 14 is stacked on the upper side of the pinned magnetic layer 13, the manufacturing apparatus 20 unloads the substrate 11 from the MgO chamber 24 and transports it in the order of the first upper layer chamber 25A and the second upper layer chamber 25B. When the manufacturing apparatus 20 carries the substrate 11 into the first upper layer chamber 25 </ b> A, the first upper layer chamber 25 </ b> A is driven to stack the free magnetic layer 15 on the tunnel barrier layer 14. In addition, when the manufacturing apparatus 20 carries the substrate 11 into the second upper layer chamber 25 </ b> B, the second upper layer chamber 25 </ b> B is driven to stack the protective layer 16 on the free magnetic layer 15.

When the protective layer 16 is stacked, the manufacturing apparatus 20 unloads the substrate 11 from the second upper layer chamber 25 </ b> B and loads it into the LL chamber 22. Similarly, the manufacturing apparatus 20 drives the first, second, and third lower layer chambers 23A, 23B, and 23C, the MgO chamber 24, and the first and second upper layer chambers 25A and 25B, respectively. Then, the underlayer 12, the pinned magnetic layer 13, the tunnel barrier layer 14, the free magnetic layer 15, and the protective layer 16 are stacked and carried into the LL chamber 22. When the film forming process is completed for all the substrates 11, the manufacturing apparatus 20 opens the LL chamber 22 to the atmosphere and causes all the substrates 11 to be carried out of the manufacturing apparatus 20.

(Example)
Next, the effects of the present invention will be described with reference to examples.
A silicon substrate having a silicon oxide film is used as the substrate 11, and the substrate 11 is sequentially transferred to the first, second, and third lower layer chambers 23 </ b> A, 23 </ b> B, and 23 </ b> C, and a Ta layer is formed as the underlayer 12. As the layer 13, a laminated structure made of PtMn / Co / Ru / CoFeB was formed.

Subsequently, the substrate 11 was transferred to the MgO chamber 24, and an MgO layer was laminated on the fixed magnetic layer 13. At this time, an MgO target having a diameter of 100 (mm 2) and a thickness of 5 (mm 2) was used as the target T, and 200 (W 2) high frequency power was supplied to the target T as sputtering power. Also, Ar is used as the sputtering gas, and the sputtering pressure is 1.2 × 10 ⁻² (Pa ² ).
The flow rate of Ar was adjusted so as to be ˜2.4 × 10 ⁻¹ (Pa). And target T
The strength of the horizontal magnetic field on the surface was set to 2000 (Oe) and 2600 (Oe).

  Next, the substrate 11 is transferred to the first and second upper layer chambers 25A and 25B, a CoFeB layer is formed as the free magnetic layer 15, a Ta layer is formed as the protective layer 16, and the two magnetoresistive elements 10 according to the embodiments are formed. Got. And the magnetoresistive change rate (MR ratio) of each Example was each measured using the magnetoresistive effect measuring apparatus. The MR ratio of the example is shown in FIG.

(Comparative example)
In the MgO chamber 24, the strength of the horizontal magnetic field on the surface of the target T is set to 800 (Oe) and 1750 (Oe), and the other conditions are the same as in the example, and two magnetoresistive elements 10 as comparative examples are obtained. It was. And MR ratio of each comparative example was measured using the magnetoresistive effect measuring apparatus. The MR ratio of the comparative example is shown in FIG.

FIG. 4 is a diagram showing the relationship between the strength of the horizontal magnetic field and the MR ratio.
In FIG. 4, the MR ratio of the magnetoresistive element 10 shows a value of less than 200% in the region (comparative example) where the horizontal magnetic field is less than 2000 (Oe), and the value is linearly increased as the horizontal magnetic field increases. You can see that it increases. Further, the MR ratio of the magnetoresistive element 10 shows a value of 200% or more in a region (example) where the horizontal magnetic field is 2000 (Oe) or more, and the value can be made substantially constant regardless of the increase of the horizontal magnetic field. I understand.

  That is, the MR ratio of the magnetoresistive element 10 can be improved and the value can be stabilized as much as the horizontal magnetic field strength is 2000 (Oe) or more. As a result, the magnetoresistive element 10 having an MR ratio of 200% or more can be manufactured with high reproducibility.

(Magnetic device)
Next, a magnetic memory as a magnetic device manufactured using the method for manufacturing a magnetic device will be described. FIG. 5 is a schematic cross-sectional view showing the magnetic memory 40.

  A thin film transistor Tr is formed on the substrate 11 of the magnetic memory 40. The diffusion layer LD of the thin film transistor Tr is connected to the magnetoresistive element 10 via the contact plug CP, the wiring ML, and the lower electrode layer 41.

  The magnetoresistive element 10 includes a fixed magnetic layer 13 stacked on the upper side of the lower electrode layer 41, a tunnel barrier layer 14 stacked on the fixed magnetic layer 13, and a free magnetic layer 15 stacked on the tunnel barrier layer 14. This is a TMR element.

  A word line WL that is spaced below the lower electrode layer 41 is disposed below the magnetoresistive element 10. The word line WL is formed in a strip shape extending in a direction perpendicular to the paper surface. Further, on the upper side of the magnetoresistive element 10, a band-like bit line BL extending in a direction orthogonal to the word line WL is disposed. That is, the magnetoresistive element 10 is disposed between the word line WL and the bit line BL that are orthogonal to each other.

  In the magnetoresistive element 10, the pinned magnetic layer 13, the tunnel barrier layer 14, and the free magnetic layer 15 are stacked on the upper side of the lower electrode layer 41, and the pinned magnetic layer 13, tunnel barrier layer 14, and free magnetic layer 15 are etched. It is formed by applying. The pinned magnetic layer 13, the tunnel barrier layer 14, and the free magnetic layer 15 are formed using the magnetoresistive element manufacturing apparatus 20. Therefore, the magnetic memory 40 can give high reproducibility to the magnetoresistive effect of the magnetoresistive element 10, and can improve the productivity.

As described above, according to the present embodiment, the following effects can be obtained.
(1) In the above embodiment, the magnetoresistive element manufacturing apparatus 20 uses the magnetic circuit 37 to form a leakage magnetic field on the surface of the target T, and the horizontal magnetic field intensity on the surface of the target T is 2000 (Oe) to 3000. (Oe). And when the tunnel barrier layer 14 is laminated | stacked, the target T which has a magnesium oxide as a main component is sputter | spattered when the horizontal magnetic field in the surface is 2000 (Oe)-3000 (Oe).

  Therefore, the lower limit value of the sputtering pressure can be lowered and the lower limit value of the sputtering power can be lowered as much as the horizontal magnetic field is 2000 (Oe) or more. Therefore, the range of sputtering conditions can be expanded toward the region where the (100) plane orientation of the MgO layer becomes strong. As a result, the range of sputtering conditions for obtaining a predetermined MR ratio can be expanded. As a result, the reproducibility of the magnetoresistive effect can be improved.

  (2) Moreover, according to the said embodiment, a MgO layer can be formed in the area | region where MR ratio is stabilized. As a result, a high level of MR ratio can be provided stably, and the reproducibility of the magnetoresistive effect can be further improved.

(3) Further, the unnecessary expansion of the magnetic circuit 37 can be avoided as much as the horizontal magnetic field is suppressed to 3000 (Oe) or less, and the enlargement of the manufacturing apparatus 20 can be suppressed.
(4) In the above embodiment, the distance between the surface of the target T and the outer magnet M1 or the target so that the intensity of the horizontal magnetic field on the surface of the target T is 2000 (Oe) to 3000 (Oe). The distance between T and the inner magnet M2 is changed. Therefore, the reproducibility of the magnetoresistive effect can be improved by a simple method without a large-scale change of the MgO chamber 24.

In addition, you may implement each said embodiment in the following aspects.
In the above embodiment, the integrated value of the vertical magnetic field in the sputtering chamber 31S may be zero. Alternatively, a so-called unbalanced magnetron method in which the integrated value of the vertical magnetic field in the sputtering chamber 31S has a non-zero value may be used. That is, the present invention is not limited to the strength of the vertical magnetic field, and any structure may be used as long as the horizontal magnetic field is 2000 (Oe) to 3000 (Oe) on the surface of the target T.

  In the above embodiment, the magnetic device is embodied in the magnetic memory 40. For example, the magnetic device may be embodied as an HDD read head.

1 is a side sectional view showing a magnetoresistive element of an embodiment. Similarly, the top view which shows the manufacturing apparatus of a magnetic device typically. Similarly, the sectional side view which shows a MgO chamber. Similarly, the figure which shows the relationship between a horizontal magnetic field and a magnetoresistance change rate. Similarly, sectional side view which shows a magnetic memory. Similarly, an X-ray diffraction spectrum showing the relationship between the orientation of MgO and the sputtering pressure. Similarly, an X-ray diffraction spectrum showing the relationship between the orientation of MgO and the sputtering power. Similarly, the figure which shows the relationship between a sputtering pressure and a horizontal magnetic field. Similarly, the figure which shows the relationship between sputtering electric power and a horizontal magnetic field.

Explanation of symbols

  T ... target, ... 10 magnetoresistive element, 11 ... substrate, 20 ... magnetic device manufacturing apparatus, 37 ... magnetic circuit, 40 ... magnetic memory constituting the magnetic device.

Claims (5)

Forming a first magnetic layer on a substrate;
Laminating a magnesium oxide layer on the first magnetic layer;
Laminating a second magnetic layer on the magnesium oxide layer;
A method of manufacturing a magnetic device comprising:
The step of laminating the magnesium oxide layer includes sputtering the target by forming a horizontal magnetic field having a strength of 2000 (Oe) to 3000 (Oe) on the surface of the target mainly composed of magnesium oxide.
A method of manufacturing a magnetoresistive element. It is a manufacturing method of the magnetoresistive element according to claim 1,
The step of laminating the magnesium oxide is performed between the surface of the target and the magnetic circuit so that a horizontal magnetic field leaking from the surface of the target is 2000 (Oe) to 3000 (Oe) on the surface of the target. Changing the distance,
A method of manufacturing a magnetoresistive element. A method of manufacturing a magnetic device including a magnetoresistive element,
Manufacturing the magnetoresistive element by using the magnetoresistive element manufacturing method according to claim 1,
A method of manufacturing a magnetic device. A transport unit for transporting the substrate;
A first film forming unit connected to the transport unit and forming a first magnetic layer on the substrate;
A second film forming unit connected to the transport unit and stacking a magnesium oxide layer on the first magnetic layer;
A device for manufacturing a magnetic device, comprising: a third film forming unit coupled to the transport unit and laminating a second magnetic layer on the magnesium oxide layer;
The second film forming unit includes:
A target mainly composed of magnesium oxide;
A magnetic circuit for forming a horizontal magnetic field having a strength of 2000 (Oe) to 3000 (Oe) on the surface of the target;
An apparatus for manufacturing a magnetoresistive element, comprising: An apparatus for manufacturing a magnetic device including a magnetoresistive element,
The apparatus for manufacturing a magnetoresistive element according to claim 4 is provided for manufacturing the magnetoresistive element.
An apparatus for manufacturing a magnetic device.

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