JP2003258335A - Manufacturing method for tunneling magneto resistive effect device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tunneling magneto resistive effect device which exhibits greater magneto resistivity with reduced degrading of a TMR ratio due to bias voltage, and which has higher heat resistance. <P>SOLUTION: In a manufacturing method for a tunneling magneto resistive effect device, a process for forming a tunneling insulating layer of the tunneling magneto resistive effect device comprises a first process for forming a conducting layer being a tunneling insulating layer precursor, and a second process for oxidizing the conducting layer. In the first process for forming the conducting layer the rate of film formation is 0.4 Å/sec or less. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a high density magnetic recording / reproducing head (magnetic disk, magneto-optical disk, magnetic tape, etc.), a magnetic sensor used in automobiles, and a magnetic random access memory (MRAM). The present invention relates to a method of manufacturing a tunnel magnetoresistive effect element.

[0002]

2. Description of the Related Art The rapid spread of information innovation due to the spread of the Internet and the development of advanced communication networks have increased the necessity of handling a large amount of information at high speed. Above all, the hard disk drive (HDD) stores a large amount of information,
Moreover, it is an external recording device capable of high-speed transfer. Giant Magnet Resistive e
The recording density is 60% to 1 yearly due to technological innovations such as improvement of read head performance using ffect (GMR effect).
It is growing at 00%. In addition, mobile communication devices such as mobile phones and laptop computers are now indispensable for daily life, and various information such as character information and moving image information is exchanged through the mobile devices. Even in this mobile device, there is an increasing need for a small-sized, lightweight, low-consumption recording medium for storing and transferring a large amount of information in an instant, and flash memory and FeRAM (Ferro electric Rand)
om Access Memory) and other non-volatile memories are being developed. As a large-capacity, high-speed non-volatile memory device, the tunnel magnetoresistive effect (Tunnel Magnet
Resistive effect: MRAM (Magnet) that uses the TMR effect
Expectations for ic Random Access Memory) are high.

When a voltage is applied to a multilayer film in which two ferromagnetic layers are laminated via an insulating layer of about several nm, a tunnel current is generated between the insulating layers. In the case of a ferromagnet, the number of electrons tunneling differs depending on the spin because the density of states on the Fermi surface depends on the spin, so that the two ferromagnetic layers are ferromagnetic when the magnetizations are parallel and antiparallel. Conductance of tunnel electrons (reciprocal of resistance) reflecting the density of states of the body
The phenomenon that is greatly different is the TMR effect. The first report of the TMR effect was published in 1975 by Julliere (Physics Letters, vol.
(1975). No. 3, p225). Jullier is Fe
A magnetoresistance change rate (MR ratio) of 14% in the / Ge-O / Fe junction was reported, but it was a phenomenon at a cryogenic temperature of 4.2K. In 1995, Miyazaki (Journal of Magnetism and M
agneticMaterials 139 (1995) 231.) and Moodera (Physic
al Review Letters 74 (1995) 3273.) et al. independently reported very large MR ratios of 10% or more at room temperature for Fe / Al-O / Fe and FeCo / Al-O / Co junction films, respectively. Starting with, the research and development of TMR phenomenon for application to next-generation magnetic heads for HDDs and MRAM is accelerating.

The operating principle of the TMR element will be described with reference to FIG. A first ferromagnetic layer 11, a tunnel insulating layer 12, and a second ferromagnetic layer 13 are laminated in this order on a substrate (not shown), and FIG. 1 shows a cross-sectional view of the film. The tunnel insulating layer 12 is thin enough to allow electrons to tunnel, and the magnetization reversal fields (coercive forces) of the first ferromagnetic layer 10 and the second ferromagnetic layer 12 are made different so that an appropriate external magnetic field is applied. By doing so, the magnetizations are parallel as shown in FIGS.
It is possible to realize an antiparallel state. FIG. 14 (c)
Shows a magnetoresistance curve (MR curve) when a magnetic field is applied parallel to the film surface of the TMR element 10. The figure shows a state in which the magnetization of one magnetic layer (free magnetic layer) is reversed and the magnetization of the other ferromagnetic layer (fixed magnetic layer) does not change. The arrows shown in FIG. 2 represent the magnetization directions of the two ferromagnetic layers, and the MR ratio increases in the antiparallel state. TMR element 1
A tunnel current flows by applying a voltage in a direction substantially perpendicular to the film surface of 0. In a ferromagnet, electrons have different states of upward spins and downward spins.Therefore, in order for electrons to tunnel from one ferromagnetic layer to the other, the spin direction of the electrons does not reverse in the tunneling process. , Further suppose that the electrons of upward spin and downward spin move to the same state,
When the resistances when the magnetizations of the first ferromagnetic layer 11 and the second ferromagnetic layer 13 are parallel and antiparallel are Rp and Rap, respectively, the magnetoresistive ratio (MR ratio) is expressed by the equation (1). To be done.

MR ratio = (Rap−Rp) / Rp = 2P ₁ P ₂ / (1−P ₁ P ₂ ) (1) Equation (1) where P1 and P2 are spin polarizations of the first and second ferromagnetic layers, respectively. Represents a rate. P1 and P2 are given by Eq. (1), where N _up and N _down are the numbers of electrons in the upward and downward spins, respectively, and P ₁ (P ₂ ) = (N _up −N _down ) / (N _up + N _down ) To be In general, the spin polarizabilities P ₁ and P ₂ depend on the type of ferromagnetic material, and since the physical quantity relating to the properties of the tunnel insulating layer is not included from the equation (1), the MR ratio of the TMR element depends on the tunnel insulating layer. A large MR ratio can be obtained by using a material having a large spin polarization of the adjacent ferromagnetic layers. For example, when a ferromagnetic material having a spin polarizability of 0.5 is used, the MR ratio is expected to be 67% from the equation (1). However, in reality, the MR ratio is substantially reduced due to the decrease in polarizability due to magnetic impurities existing in the tunnel insulating layer and near the interface, and inelastic scattering tunnels other than the tunnel due to irregularities and impurity defects at the interface. .

[0006]

[Problems to be Solved by the Invention] A TMR element is used for a high-density magnetic head or a high-speed, large-capacity nonvolatile solid-state magnetic memory (MRA).
Considering the device application to M) etc., an element with a large MR ratio is required because of its high output. Furthermore, in device manufacturing, in addition to the need for reproducibility of TMR characteristics on a wafer and between lots, there is no deterioration of TMR characteristics in the manufacturing process, that is, process stability is an important factor.

However, it is generally considered that a material having a high polarizability may be used for the two ferromagnetic layers adjacent to the tunnel insulating layer in order to obtain a large MR ratio.
Compared with the result of calculating the MR ratio from the value obtained by determining the spin polarizability of the ferromagnetic material by the insulator / superconductor junction, the experimental data of the actual TMR element gives only a small MR ratio, which limits the high MR ratio. There is a problem. This is considered to be due to defects in the thin tunnel insulating layer and defects at the tunnel insulating layer / ferromagnetic layer interface. Conventionally, FIG.
In the structure of the TMR element of (a) and (b), the method of forming the ultrathin tunnel insulating layer 12 is, for example, the method of Miyazaki et al., An Al layer is sputtered on the first ferromagnetic layer 11 on the substrate side. A common method is to stack at a film-forming rate of 5Å / sec and oxidize naturally in the atmosphere (Journal of Magnetism and
Magnetic Materials 139 (1995) 231.), it was difficult to obtain good TMR characteristics by this method because impurity gas in the atmosphere is formed in the tunnel insulating layer. Furthermore, Miyazaki et al. Have performed a method of forming Al2O3 by laminating an Al layer under the same film forming conditions and then plasma-oxidizing the Al layer in a mixed gas atmosphere of argon and oxygen in a vacuum. However, in these methods, the Al layer deposited on the first ferromagnetic layer 11 has a high Al film formation rate, so the first ferromagnetic layer 1
Since Al atoms diffuse into 1 and unoxidized Al atoms remain, the magnetic impurities that cause the decrease of spin polarizability are present at the tunnel insulating layer / ferromagnetic layer interface.
MR ratio cannot be obtained. It is also possible to form an Al oxide by sufficiently oxidizing Al atoms mixed in the ferromagnetic layer to form a tunnel insulating layer, but in this case, the ferromagnetic layer is also oxidized and spin polarization is caused. There is a problem that the MR characteristics are deteriorated due to a decrease in the ratio, and the MR characteristics are deteriorated because a uniform tunnel insulating layer cannot be obtained due to locally thick or thin portions of the tunnel insulating layer.

Further, in the TMR element, when a bias voltage is applied, the MR ratio is reduced and the output is lowered. As a cause of the decrease in MR ratio due to the application of the bias voltage, magnons are excited in the ferromagnetic layer by the bias voltage and spins of tunnel electrons are not preserved, or defects in the insulating layer increase inelastic scattering. It is believed that this causes the MR ratio to decrease. However, there are various theories about the root cause of this problem, and although there are problems that must be solved one by one, there is a problem that the film quality of the tunnel insulating layer is an important factor.

When the TMR element is applied to a device such as a high density magnetic head or a non-volatile solid magnetic memory (MRAM), a spin valve type TMR element using an antiferromagnetic layer is practical. However, in the manufacturing process of magnetic heads and MRAM,
About 250 ℃ -300 ℃ for magnetic head, 400 ℃ -450 for MRAM
A high temperature thermal process of about ℃ is required. It has been reported that the MR ratio of the TMR element is increased by heat treatment in a magnetic field at 250 ° C to 300 ° C rather than during film formation. This is mainly due to the report of the spin valve type TMR element using an antiferromagnetic material. Mainly due to the increase of the exchange bias magnetic field between the antiferromagnetic layer and the ferromagnetic layer.
This is because the antiparallel magnetization state of the two ferromagnetic layers is realized. However, since the dependence of MR ratio on the heat treatment temperature is very large, it is considered that it is difficult to control most of the TMR characteristics in the report on its reproducibility. Besides, M
There is a problem that the R ratio sharply decreases due to heat treatment at 300 ° C or higher, and TMR characteristics deteriorate, which is a problem in MRAM manufacturing.
Since a 400 ° C thermal process is inevitable, an urgent solution is desired. The problem that the TMR element is vulnerable to this heat treatment is also considered to be due to the film quality of the tunnel insulating layer. Especially as a method of creating a tunnel insulating layer,
Including the above, after the Al layer is formed, a method such as a natural oxidation method of introducing oxygen gas in a vacuum to oxidize it or a plasma oxidation method of generating a plasma to oxidize is generally performed. There is. However, as a condition for laminating the Al layer,
Generally, the deposition rate is 1 Å / sec or more and the incident energy is large and the growth rate is fast. In this conventional example, the Al atoms, which are the tunnel insulating layer precursor, diffuse into the ferromagnetic layer and remain as magnetic impurities that reduce the spin polarizability, so that the resistance to the heat treatment process is low. it is conceivable that. In addition, even if Al atoms are mixed or diffused in the ferromagnetic layer, sufficient oxidation conditions
Although it is possible to oxidize Al atoms, in that case, there arises a problem that the MR ratio is lowered and the bias voltage characteristic is deteriorated due to local unevenness of the tunnel insulating layer / ferromagnetic layer interface. Moreover, when heat treatment is further applied, the unevenness of the tunnel insulating layer becomes large due to the influence of Al atoms at the local interface, and there is a risk of deterioration of TMR characteristics due to pinholes and the like in the tunnel insulating layer. There is a problem.

Further, since the first ferromagnetic layer is laminated from the substrate on various structures, surface roughness of several nm to several tens nm is generated on the film surface. When a metal layer (Al layer), which is a precursor of the tunnel insulating layer, is laminated on the surface with irregularities on the surface to form an ultrathin layer with a thickness of several nm or less, the surface roughness is further increased when the film formation rate is high. As a result, the unevenness at the tunnel insulating layer / ferromagnetic layer interface becomes large. Even if the unevenness is large, it is sufficient if the film thickness of the tunnel insulating layer is uniform, but it is easy for local areas with thick or thin film thickness to exist, causing a decrease in MR ratio and deterioration of bias voltage characteristics. . Furthermore, 250 ℃
When the high temperature heat treatment of ~ 300 ℃ or more is performed, the unevenness of the interface further occurs due to the local film thickness distribution of the tunnel insulating layer, and the TMR
There is a problem that an element having a low heat resistant temperature is formed.

The object of the present invention is to solve the above-mentioned conventional techniques, control the manufacturing method for forming a conductive layer which is a tunnel insulating layer precursor, reduce the deterioration of the ferromagnetic tunnel effect characteristics, and increase the characteristics. TMR with high MR ratio and high heat resistance
An object is to provide an element and a manufacturing method thereof.

[0012]

According to the manufacturing method of the present invention, a first ferromagnetic layer, a tunnel insulating layer, and a second ferromagnetic layer are laminated in this order on a substrate, and the first ferromagnetic layer is formed. And a second ferromagnetic layer, the tunnel magnetoresistance effect element having different tunnel magnetoresistance due to the difference in relative angle between the magnetization directions, a first step of forming a conductive layer which is the tunnel insulating layer precursor, and the conductive layer Is oxidized in an oxygen atmosphere in the second step, and in the first step, the conductive layer is
A tunnel magnetoresistive effect element manufacturing method characterized by being formed from at least one of Al, Mg, Si, and Ta at a film forming rate of 4 Å / sec or less, which solves the above problems.

The manufacturing method of the present invention may include performing the first step and the second step a plurality of times.

In the manufacturing method of the present invention, the conductive layer formed in the first step is oxidized in vacuum in the second step. The film thickness of the conductive layer formed in the first step is 4 nm or less.

The manufacturing method of the present invention comprises a second step of oxidizing the conductive layer.
In the above step, at least one of a natural oxidation method, a plasma oxidation method and a radical oxidation method is used.

The manufacturing method of the present invention may include a third step of forming the first ferromagnetic layer and a fourth step of forming the second ferromagnetic layer. Furthermore, at least one of the first ferromagnetic layer or the second ferromagnetic layer contains at least one of Fe, Co, and Ni as a main component, and
It may include at least one selected from Pd, Pt, Ir, Rh, and Ru.

If the tunnel magnetoresistive element manufactured by the manufacturing method of the present invention is provided with a shield part,
A shield type magnetoresistive head is constructed. Further, if the magnetoresistive effect element manufactured by the manufacturing method of the present invention is provided with a yoke for introducing a magnetic field to be detected into the magnetoresistive effect element portion, a yoke type magnetoresistive effect head or a magnetoresistive effect element having a yoke is provided. Is configured.

In the tunnel magnetoresistive effect element portion produced by the manufacturing method of the present invention, an information read conductor line (sense line) portion for further reading information, and an information recording conductor wire for recording information. The magnetoresistive effect memory element is configured by including the (word line portion).

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A tunnel magnetoresistive effect element (hereinafter referred to as TMR element) and a method of manufacturing a tunnel insulating layer of the present invention will be described below with reference to the drawings.

FIG. 1 shows a method of manufacturing the TMR element section 10. First, the first ferromagnetic layer 11 is formed on the substrate (not shown). Next, the first step of forming the conductive layer 12A that is the tunnel insulating layer precursor is performed. The conductive layer 12A is formed of a material containing at least one of Al, Mg, Si and Ta in vacuum at a film forming rate of 0.4 Å / sec or less. Second
In this step, pure oxygen or a mixed gas of inert gas and pure oxygen is introduced to oxidize the conductive layer 12A in vacuum to form the tunnel insulating layer 12. Second, the ferromagnetic layer 13
Are formed to form the film structure of the TMR element portion 10. In order to apply a current / voltage to the TMR element part 10 thus manufactured in the vertical direction of the film, as shown in FIG.
The TMR element may be manufactured as a structure in which the TMR element section 10 is arranged between the upper electrode 21 and the upper electrode 21.

In the method of manufacturing the tunnel insulating layer 12 of the present invention, the conductive layer 12 that is the precursor of the tunnel insulating layer 12 is used.
As a method of oxidizing A in a vacuum, a natural oxidation method in which a mixed gas of pure oxygen or an inert gas such as Ar and pure oxygen is introduced to oxidize, or a mixed gas of an inert gas such as Ar and pure oxygen is used. By using a method in which plasma is generated to oxidize the surface of the conductive layer 12A by plasma or a method in which radical oxidization is performed, a homogeneous and good pinhole-free tunnel insulating layer 12 is formed.

As in the present invention, the conductive layer 12A is formed at a film forming rate of 0.
The first ferromagnetic layer 1 is formed by forming it at 4 Å / sec or less.
The mixing and diffusion of atoms of the conductive layer 12A into 1 are reduced,
A uniform conductive layer 12A can be formed. And the conductive layer 12A
A uniform film is formed in the tunnel insulating layer that is formed by oxidization in vacuum. The film formation rate when forming the conductive layer 12A is 0.
When controlled to 4 Å / sec or less, the coverage is good even if irregularities are generated on the surface of the first ferromagnetic layer 11. In other words, the smoothness of the interface between the tunnel insulating layer and the ferromagnetic layer is improved, and a uniform tunnel insulating layer with no locally thick or thin portions can be formed, resulting in a high tunnel magnetic resistance ratio (MR ratio). Can be formed. The first or second conductive layer material
Since there is no mixing or diffusion of atoms into the ferromagnetic layer and there is no defect at the interface between the tunnel insulating layer and the ferromagnetic layer by the method of forming the tunnel insulating layer 12 of the present invention, even if a high heat treatment of 200 ° C. or higher is performed, It is possible to obtain a TMR element without deterioration of TMR characteristics due to diffusion.

In the step of manufacturing the tunnel insulating layer 12 of the present invention, at least one of the first step of forming the conductive layer 12A and the second step of oxidizing the conductive layer 12A is carried out a plurality of times to form the tunnel. The insulating layer 12 may be formed. For example, when the tunnel insulating layer 12 is formed by performing the first step and the second step for three cycles with one cycle, the following steps are performed. After forming the first ferromagnetic layer 11, the conductive layer 12A-1 is formed within a film thickness range of 0.2 nm to 4 nm. After the first step 1-1, the conductive layer 12A-1 is oxidized in vacuum. Tunnel insulating layer 12-1 through step -1
Is formed, and then the conductive layer 12A-2 is further formed by 0.2 nm to 4 nm.
Of the conductive layer 12A-
The tunnel insulating layer 12-2 is formed through the 2-2 step of oxidizing 2 in vacuum to form the tunnel insulating layer 12. In this way, by performing the step of forming the conductive layer and the step of oxidizing the conductive layer in vacuum multiple times, it is possible to sufficiently oxidize the conductive layer and manufacture a good-quality tunnel insulating layer without pinholes. It will be possible. In addition, as described above, the conductive layer 12A-2 (1 is formed on the tunnel insulating layer 12-1 (12-2).
Even when 2A-3) is formed, a part of the material forming the conductive layer 12A-2 (12A-3) is included in the tunnel insulating layer 12-1 (12- because the film forming rate is 0.4 Å / sec or less.
2) The tunnel insulating layer 12-
1 (12-2) on the conductive layer 12A-2 (12A-3) has good coverage, so the tunnel insulating layer 12-2 (12-3)
Becomes a homogeneous film, and a TMR element exhibiting excellent TMR characteristics can be obtained. When the step of forming the conductive layer and the step of oxidizing the conductive layer are carried out a plurality of times as described above, there is an effect that a uniform tunnel insulating layer having good insulating characteristics is formed. Is 0.4Å /
If it is less than a second, the film thickness can be controlled well, and since the film thickness can be controlled up to several Å, the yield of the TMR element having the tunnel insulating layer created in this way is very high, and the efficiency in device manufacturing is dramatically increased. Can be expected to improve. Further, for example, after forming the first ferromagnetic layer 11, the conductive layer 12A is formed within the range of 0.2 nm to 4 nm, the conductive layer 12A is naturally oxidized in vacuum, and further plasma oxidized or radically oxidized in an oxygen atmosphere. The tunnel insulating layer 12 may be formed by oxidation.

The thickness of the conductive layer 12A, which is the precursor of the tunnel insulating layer 12, is 0.2 nm or more and 4 nm or less, more preferably 0.3 n.
It is desirable that it is m or more and 2 nm or less.

The first ferromagnetic layer 11 and the second ferromagnetic layer 13
As the magnetic material used in the above, it is preferable to use a magnetic alloy containing at least one of Fe, Co, and Ni as in the conventional case, and further, in the first or second ferromagnetic layers 11 and 13, Fe,
Contains at least one of Co and Ni, and further contains Pt, Pd, Ir, Rh,
It is even better to use a magnetic alloy containing at least one kind of Ru.
In particular, a magnetic alloy containing Pt, Pd, Ir, Rh, and Ru is used as the conductive layer 12
In the step of forming the conductive layer 12A, the conductive layer 1 is used in the first ferromagnetic layer 11 which is also the underlayer of A.
The tunnel insulating layer 12 has an effect of suppressing mixing or diffusion of 2A atoms into the first ferromagnetic layer 11, and is manufactured through a process of oxidizing in a vacuum after forming the conductive layer 12A. Makes it possible to form a smooth interface with the first ferromagnetic layer 11 and obtain a TMR element exhibiting high MR / high heat resistance characteristics and high bias dependence. Pt, P
d, Ir, Rh, Ru are magnetic elements (F
(e, Co, Ni) is suppressed and oxidation of the conductive layer 12A is promoted to smooth the interfaces between the first ferromagnetic layer 11 and the tunnel insulating layer 12 and between the second ferromagnetic layer 13 and the tunnel insulating layer 12. Due to the action of forming. Even if the TMR element 10 thus formed is subjected to heat treatment at 200 ° C. or higher, oxygen in the tunnel insulating layer 12 is suppressed from diffusing into the first ferromagnetic layer 11 and the second ferromagnetic layer 13, and It has a function of smoothing the insulating layer / ferromagnetic layer interface, and it is possible to provide a TMR element having high heat resistance. Here, the tunnel insulating layer 12 included in the first ferromagnetic layer 11 or the second ferromagnetic layer 13 is included.
The content of Pt, Pd, Ir, Rh, and Ru near the interface is preferably 50 at% or less in terms of atomic ratio in order to obtain good TMR characteristics.

The spin shown in FIG. 3 having a structure in which an antiferromagnetic material is arranged in order to make the magnetization reversal fields of the first ferromagnetic layer 11 and the second ferromagnetic layer 13 of the TMR element portion 10 different from each other. It may be a valve type TMR element. An exchange coupling magnetic field is generated in the first ferromagnetic layer 11 by the antiferromagnetic layer 14, and the first ferromagnetic layer 11 becomes a fixed magnetic layer whose magnetization rotation is difficult with respect to an external magnetic field. 13 is a free magnetic layer whose magnetization is easily rotated by an external magnetic field. In FIG. 3, the antiferromagnetic layer 14 is arranged in the first ferromagnetic layer 11, but the antiferromagnetic layer 14 may be arranged in the second ferromagnetic layer 13.

Here, the antiferromagnetic layer 14 is preferably made of metal antiferromagnetic material A-Mn (A is at least one selected from Pt, Ir, Rh, Fe, Cr and Ru). When forming the antiferromagnetic layer 14 between the first ferromagnetic layer 11 and the substrate (not shown) as shown in FIG. 3, Ta, Pt, Pd, Ru, Cr, Nb,
Ni-Fe, Ni-Fe-X (X is at least one selected from Cr, Pt, Pd, and Nb) and the like may be used.

First ferromagnetic layer 11 and second ferromagnetic layer 13
May be a film made of one kind of magnetic material or a laminated film of two or more kinds of magnetic materials.

In FIG. 3, the first ferromagnetic layer 11 which is a pinned magnetic layer is laminated with two ferromagnetic layers 11-1 and 11-2 via a non-magnetic layer 15 selected from Ru, Cu, Cr and the like. A TMR element having the structure shown in FIG. 4 which is a ferri film may be used.
The two ferromagnetic layers stacked via the non-magnetic layer 15 such as Ru have a stable magnetic structure in which their magnetization directions are arranged antiparallel to each other, and prevent the magnetic field from leaking from the end of the film.
It is possible to stabilize the magnetization direction. Such a structure of the pinned magnetic layer may of course be used for the pinned magnetic layer of the dual structure spin valve type TMR element shown in FIG. 5, which will be described later.

FIG. 5 shows a dual structure spin valve TMR in which two tunnel insulating layers and three ferromagnetic layers are alternately laminated.
It is an element. In FIG. 5, a first antiferromagnetic layer 30, a first ferromagnetic layer 31, a first tunnel insulating layer 32, a second ferromagnetic layer 33, and a second tunnel insulating layer are provided on a substrate (not shown). 34, the third ferromagnetic layer 35, and the second antiferromagnetic layer 36 are sequentially stacked, and as shown in FIG. 3, the first and second antiferromagnetic layers 30 and 36 form the first and second antiferromagnetic layers. Each of the ferromagnetic layers 31 and 35 of No. 3 serves as a fixed magnetic layer whose magnetization direction is fixed by an exchange bias magnetic field and does not easily reverse magnetization by an external magnetic field. Functions as an easy free magnetic layer. By using two tunnel insulating layers, the bias voltage (Vh) at which the MR ratio is halved is larger than that of the TMR element using one tunnel insulating layer as shown in Fig. 3, and the bias voltage dependence is superior to the dual spin valve. ing. Here, in order to obtain a TMR element having an MR ratio, a bias voltage characteristic, and a heat resistance superior to those of the conventional one, a tunnel insulating layer precursor is formed at a film forming rate of 0.4 Å / second or less as shown in FIG. Further, a smooth interface between the tunnel insulating layer and the adjacent ferromagnetic layer is formed by going through the manufacturing process of forming the tunnel insulating layer by performing oxidation (natural oxidation, plasma oxidation, radical oxidation) in vacuum. Is an excellent TM that prevents the deterioration of MR characteristics due to the inclusion of the tunnel insulating layer precursor in the ferromagnetic layer.
An element having R characteristics can be formed. Here, even if the Fe-Co-Ni alloy containing Pt, Pd, Ru, Rh, and Ir is used for at least one of the first, second, or third ferromagnetic layers 31, 33, and 34, There is a similar effect in the manufacturing method of the tunnel magnetoresistive effect element.

As described above, the tunnel insulating layer and the tunnel magnetoresistive effect element manufacturing method of the present invention are used to form the structure shown in FIG.
A structure in which electrodes are arranged above and below the TMR element portion 10 as shown in (c) so that a current flows in the direction perpendicular to the film surface of the tunnel insulating layer is shown in FIG. 2, and more specifically, as shown in FIG. To create the device 100, a physical or chemical etching method such as ion milling, FIB (focus ion beam), RIE (reactive ion etching) used in a semiconductor process or a GMR head manufacturing process, or the like,
It is possible to fabricate an element as shown in FIG. 7 by performing fine processing in combination with a photolithography technique using a stepper, an EB method or the like for forming a fine pattern.
6 (a) to 6 (h) show the steps of processing the mesa type element as shown in FIG. In the step (a), the film of the TMR element portion 10 is formed on the lower electrode portion 20 formed on the substrate, and a part of the protective layer / upper electrode portion 21 is formed. In FIG. 6 (a)
As the film structure of the TMR element portion 10, the film structure shown in FIG. 1C is shown as an example. Next, in the step (b), the lower electrode portion 5
After applying and baking a resist as a pattern for processing No. 03, a resist pattern is formed by performing processing such as photolithography or EB exposure and development, and etching by ion irradiation is performed to process the lower electrode portion 503. In step (c), a processing pattern for cutting out the TMR element portion 10 into a mesa shape is transferred again to a coated resist, and the time required for etching is controlled to form a mesa type joint portion having an optimum thickness. To do. In step (d), an interlayer insulating layer is deposited before the resist used for processing is peeled off to surround the mesa-type junction with the interlayer insulating layer 501. In step (e), the resist and the interlayer insulating layer 501 on the resist are removed by lift-off cleaning, and step (f)
At, the upper electrode portion 502 is deposited. In the present embodiment shown below, Ta (5 nm) / Cu is used as the upper electrode portion 502.
A laminated film of (500 nm) / Pt (50 nm) / Ta (5 nm) was used.
In step (g), a resist pattern for wiring processing of the upper electrode portion 502 is formed by photolithography or EB exposure and development, and in step (h), pattern processing is performed by ion etching to form a desired TMR element.

As described above, the TMR element shown in FIG. 7 is prepared and a current is passed through the magnetoresistive effect element portion 505 sandwiched between the upper electrode portion 502 and the lower electrode 503 to read the voltage. The interlayer insulating layer 501 has a function of preventing an electrical short circuit between the upper electrode and the lower electrode. With the element structure as shown in FIG. 7, it becomes possible to read the output by passing a current in the direction perpendicular to the film surface of the magnetoresistive effect element section 505. It is also effective to use CMP, cluster ion beam etching, or ECR ion etching for flattening the surface of the electrodes and the like. As electrode material, Pt, Au, Cu, Ru, Al,
Starting with TiN, a low resistance material having a resistivity of 100 μΩcm or less may be used. As the interlayer insulating layer 501, a layer having excellent insulating properties such as Al ₂ O ₃ or SiO ₂ may be used.

To form the TMR element film of the present invention, pulse laser deposition (PLD), ion beam deposition (IBD), cluster ion beam or RF, DC, EC
It can be created by a sputtering method such as R, helicon, ICP or facing target, or a PVD method such as MBE method.

Using the TMR element produced by the method for manufacturing the tunnel magnetoresistive element of the present invention as described above,
As shown in Fig. 8, a magnetic random access memory (MRAM) with high output and excellent heat resistance is possible. The element used as the memory may have any configuration of the magnetic device having the above configuration. The element is, for example, a sense line 60 made of Cu or Al as a base, as represented by A1 shown in FIG.
It is arranged like a matrix at the intersection of 1 and the word line 602,
Signal information is recorded by a two-current coincidence method using a synthetic magnetic field generated when a signal current is applied to each line.

A basic example of the write operation and the read operation by the current of the magnetic memory device in FIGS. 14 to 16 will be described. In each figure, as an example, FIG.
The TMR element shown in (c) is used as a memory element. 14 to 16, the first ferromagnetic layer 11, the tunnel insulating layer 12, and the second ferromagnetic layer 13 shown in FIG.
Is represented as a TMR element. In the figure, the first ferromagnetic layer 11 is shown as a pinned magnetic layer and the second ferromagnetic layer 13 is shown as a free magnetic layer, and the second ferromagnetic layer 13 will be described as a memory layer.

In FIG. 9, in order to read the magnetization state of each element individually, a switching element 70 represented by a FET is provided for each element.
3 shows a configuration provided with 3. This random access memory can be easily constructed on a CMOS substrate. Further, FIG. 10 shows a configuration using a non-linear element 704 (or a rectifying element) for each element. Here, the nonlinear element 704
Is a varistor, a tunnel element, or 3 of the above configuration.
You may use a terminal element. This random access memory can be manufactured on an inexpensive glass substrate only by increasing the film forming process of the diode. Further, in FIG. 11, the switch element 703 for element isolation or the non-linear element 704 as shown in FIG. 9 and FIG. 10 is not used, and the element is arranged at the intersection of the direct word line 702 and the sense line / word line 701. It is configured to be. Therefore, in FIG. 16, since a current flows across a plurality of elements at the time of reading, it is desirable that the number of elements is 10,000 or less in terms of reading accuracy. With 10,000 elements or more, sufficient output cannot be obtained. FIGS. 9 to 11 show the case where the bit line is used together with a sense line for reading a resistance change by passing a current through the element. However, in order to prevent malfunction and element destruction due to the bit current, the sense line and the bit line are shown. May be separately provided. At this time, it is preferable that the bit line is arranged at a position electrically insulated from the element and parallel to the sense line. Further, in the case of current writing, it is desirable that the distance between the word line and the bit line and the memory cell is about 500 nm or less in terms of power consumption.

By using the TMR element manufactured by the method of manufacturing the TMR element of the present invention, a magnetic head having high output and excellent heat resistance as shown in FIGS. 12 and 13 can be obtained. Figure 1
The second magnetic head is an example of a so-called shield type magnetic head. In FIG. 12, two shields (upper shield 203 and lower shield 202) made of a magnetic material are provided, and the TMR element portion 201 is provided in the reproducing gap 204 of these two shield portions. Recording is winding part 2
The recording magnetic pole 206 and the upper shield 2
A signal is written to a recording medium (not shown) by a leakage magnetic field from the recording gap 207 between the recording medium 03 and the reproducing, and a signal magnetic field from the recording medium (not shown) is provided between the reproducing gap 204 (shield gap). The reading is performed by the element unit 201. Although not shown in FIG. 12, electrode portions may be connected to the upper and lower portions of the film in the TMR element portion 201, and the upper and lower electrode portions may be electrically insulated from the upper and lower shields by an insulating layer. The upper and lower shields may be connected to the upper and lower shields so that the upper and lower shields also serve as the electrode portions. For the upper and lower shields 203 and 202, soft magnetic films such as Ni-Fe, Fe-Al-Si, and Co-Nb-Zr alloys are used. A bias magnetic field is applied by a Co—Pt alloy or the like to control the magnetic domain of the layer having a role as the free magnetic layer of the TMR element unit 201. The insulating portion 208 is made of Al ₂ O ₃ or Al.
An insulating film such as N or SiO ₂ is used.

Further, as shown in FIG. 13, a TMR element having a magnetic flux guide (yoke) portion made of a magnetic material and manufactured by the manufacturing method of the present invention as an element for detecting a signal magnetic field guided by this magnetic flux guide portion. By using the portion 301, a yoke type magnetic head having a reproducing head portion having higher output and excellent heat resistance can be obtained. A signal magnetic field from a recording medium (not shown) is guided by a yoke portion 302 which also serves as a lower shield and is read by a TMR element 301 connected to the yoke portion 302. In FIG. 13, the yoke portion also serves as the lower lead portion connected to the TMR element portion 301. In FIG. 13, the entire free magnetic layer of the TMR element portion or a part thereof may also be used as the yoke portion.

(Example 1) As an embodiment of the present invention,
A method of manufacturing the spin-valve type TMR element shown in FIG. 3 will be described. A TMR film was formed by DC and RF magnetron sputtering on a Si substrate with a thermal oxide film of 500 nm in a film forming chamber having an ultimate vacuum of 1 × 10 ⁻⁸ Torr (1 Torr = 133.322 Pa) or less. First, Ta (3 nm) / Cu (5
0 nm) / Ta (3 nm) were laminated. On top of that, the Pt of the antiferromagnetic layer 14
-Mn (20 nm), was Co _{0 .75} Fe _0.25 of the first ferromagnetic layer 11 (3 nm) were laminated. Then, Al (1.5 nm) was laminated at a film forming rate of 0.3 Å / sec. In order to oxidize Al (1.5 nm), the substrate is transferred from the film formation chamber to the oxidation chamber whose ultimate vacuum is 1 × 10 ^-6 Torr or less via the transfer chamber which is evacuated to a vacuum of 10 ^-8 Torr or less. Then, pure oxygen was introduced until the pressure reached 100 Torr, the temperature was kept at room temperature for 10 minutes, and Al (1.5 nm) was oxidized to form the tunnel insulating layer 12. After exhausting oxygen, the substrate is transferred to the film formation chamber via the transfer chamber, and the Ni _0.8 Fe _0.1 (5
(nm) to form a TMR element part. The film structure of the TMR element part at this time is Pt-Mn (20 nm) / Co-Fe (3 nm) / Al-O (1.
5 nm) / Ni-Fe (5 nm). Here, the film thickness of Al-O is Al-
The Al film thickness before the oxidation of O is shown. Next, Ta (10 nm) / Pt (50 nm) was formed as a part of the protective layer and upper electrode to prepare a basic film structure of the TMR element. This sample is referred to as Example Sample A.

Ar is used as the sputter gas, and Ar of 0.8 mTorr is used.
All layers were formed by gas pressure. Here, Ta, Cu, Pt, Pt-Mn, Co _0.75 Fe _0.25 , Fe _0.85 Pt are used for forming each layer.
_{0.15, Ni 0 .56 Fe 0.14 Cr} 0.3, using Al as the target was carried out at a deposition rate of 0.4～1A / sec. When forming each layer, the film formation was performed in a magnetic field of about 100 Oe parallel to the substrate surface.

As a comparative example, the sample structure was the same as the sample sample A, except that the film formation rate of the Al conductive layer as the tunnel insulating layer precursor was 2 Å / sec. A sample of Conventional Example Sample B was prepared under the same experimental conditions.

The sample of Example sample A and the sample of Conventional example B were subjected to the element processing step shown in FIG. 6 by photolithography and ion etching to manufacture a TMR element as shown in FIG. Figure 6
In the step (f), Ta (5nm) / Cu (5
A film of 00 nm) / Pt (50 nm) / Ta (5 nm) was formed. The size of the TMR element portion was 2 μm × 6 μm. After processing the device, a magnetic field of 5 kOe was applied to the surface of the film to order PtMn and generate exchange coupling, and heat treatment was performed in the magnetic field at 280 ° C. for 3 hours.
After the heat treatment, the magnetic resistance was measured at room temperature by the DC four-terminal method. The magnetic field application direction is parallel to the magnetic field direction applied during the heat treatment. The MR ratio of the sample of the example sample A was 23%, whereas the MR ratio of the sample of the conventional example sample B was as small as 12%. The sample of the example sample A and the sample of the conventional example sample B are different only in the condition of the film forming rate of Al. Although the magnetic layer adjacent to the tunnel insulating layer is the same magnetic material (Co-Fe and Ni-Fe), the MR ratio is different in the process of forming the tunnel insulating layer. However, since the film formation rate of the Al layer that is the tunnel insulating layer precursor is as low as 0.4 Å / sec, mixing of Al atoms and other atoms at the interface with the tunnel insulating layer / first (second) ferromagnetic layer, It is considered that there was no diffusion and that the sample of the example sample A obtained a larger MR ratio than the sample B of the conventional example. Furthermore, the cross-sectional structure of the film was observed using a transmission electron microscope of these two samples. In both samples, the unevenness (schematic diagram) of the film as shown in FIG. 15 was observed. FIG. 15A shows the cross section of the film observed from the cross-sectional TEM of the example sample A and FIG. 15B of the conventional example sample B. The unevenness of the film was caused by grain growth during the lamination process of the Cu layer as the lower electrode, and the TMR element stacked on this unevenness had similar unevenness. The unevenness of the two samples, the sample A of the example and the sample B of the conventional example, is expressed by the height h of the unevenness in the film thickness direction and the length d of the unevenness in the in-plane direction shown in FIG. The d obtained from the interface between Mn) and the first ferromagnetic layer (Co-Fe) is 6 nm, and the h is 60 nm, which is almost the same as the d and h obtained from the interface between the lower electrode Cu and Ta. It was. When the maximum film thickness and the minimum film thickness of the tunnel insulating layer formed on the first ferromagnetic layer are obtained for Example Sample A and Conventional Example Sample B, respectively, Example Sample A is 1 Å or less and is very homogeneous. A tunnel insulating layer (Fig. 15)
In contrast to (a)), the conventional sample B had a locally inhomogeneous tunnel insulating layer of about 3 to 5 Å (Fig. 15).
(B)). The tunnel insulating layer of this conventional sample B has poor coverage of irregularities in the formation of an Al layer that is a precursor of the thermal insulating layer during film formation, and the Al atom has a first ferromagnetic layer (Co-Fe). ) Or diffused through grain boundaries to form an inhomogeneous Al layer, and a tunnel insulating layer having local unevenness is formed by the subsequent oxidation treatment. It is thought that this was because the ratio was small.

(Example 2) In Example 2, a TMR element in the case of forming a TMR element on an electrode having a small unevenness on the lower electrode surface was prepared according to the following procedure, and its TMR characteristics were examined. DC and R on a 500 nm Si substrate with a thermal oxide film in a deposition chamber with an ultimate vacuum of 1 × 10 ^-8 Torr or less
A TMR film was produced by the F magnetron sputtering method. The lower electrode layer Ta (3nm) / Cu (5
00nm) / Ta (20nm) was created. After that, the substrate is transferred to the ECR etching chamber via the transfer chamber that is evacuated, and Ta (20n
m) The surface was flattened by etching about 10 nm. After that, the substrate is transferred to the film forming chamber via the transfer chamber and Ta (5nm) / Ni-Fe (4nm) is formed as a part of the lower electrode, and then Ir-Mn15nm of the antiferromagnetic layer 14 is formed. ), Co _0.9 Fe _0.1 (4 nm) of the first ferromagnetic layer 11 was laminated, and an Al layer as a tunnel insulating layer precursor was laminated to 1.2 nm at a deposition rate of 0.2 Å / sec. Then, in order to oxidize Al (1.2 nm), the substrate was transferred from the film formation chamber to the oxidation chamber via the transfer chamber. The degree of vacuum reached in the oxidation chamber is 5 × 10 ^-7 Tor
Below r, a mixed gas of 1 mTorr in which the gas flow rate was adjusted at a ratio of Ar: O2 = 1: 3 was introduced into the chamber, and RF power of 80 W was supplied to one turn coil to generate oxygen plasma. The tunnel insulating layer 12 was formed by oxidizing the Al (1.2 nm) layer for 60 seconds. After that, the substrate is transported to the film forming chamber and Co _0.9 Fe _{0 of} the second ferromagnetic layer 13 is formed.
_.1 (1 nm) / Ni _0.8 Fe _0.2 (3 nm) was laminated to form a TMR element part. The film structure of the TMR element part at this time is Pt-Mn (20 nm) /
Co-Fe (4nm) / Al-O (1.2nm) / Co-Fe (1nm) / Ni-Fe (3n
m). Here, the Al film thickness before oxidation of Al—O is shown as the film thickness of Al—O. Next, as part of the protective layer and upper electrode, T
A (10 nm) / Pt (50 nm) was formed to prepare the basic film structure of the TMR element. The film forming conditions were the same as in Example 1.
This sample is referred to as Example Sample C.

As a comparative example, a conventional sample D was prepared under the same experimental conditions except that the film structure was the same as that of the sample C and the film forming rate of the Al layer as the tunnel insulating layer precursor was changed. In the sample D of the conventional example, the deposition rate of the Al layer was 2 Å / sec.

Here, the unevenness of the electrode surface due to the ECR etching on the surface of the lower electrode layer was measured in the atmosphere by an atomic force microscope (AF).
M). First, the surface roughness of the lower electrode layer (Ta (3nm) / Cu (500nm) / Ta (20nm)) before ECR etching
Ra was about 60Å. On the other hand, Ta (3nm) / Cu (500
(nm) / Ta (20 nm) lower electrode layer surface was ECR-etched, and the Ra of the Ta (5 nm) laminated surface was about 5Å or less, confirming that the smoothness was improved.

A TMR element as shown in FIG. 7 was prepared from the above-described sample C of the example and sample D of the conventional example through the element processing step shown in FIG. Similar to the first embodiment, Ta (5nm) / Cu (500nm) /
A film of Pt (50 nm) / Ta (5 nm) was formed. The magnetic resistance of these samples was measured at room temperature. Then, heat treatment was performed in a magnetic field in a vacuum of 10 ⁻⁶ Torr or less. During the heat treatment, a magnetic field of 5 kOe was applied in the same direction as during film formation, and the magnetic resistance was measured after holding at each set temperature for about 30 minutes and then cooling to room temperature. The set temperature was 200 ° C to 400 ° C at 50 ° C intervals. Table 1 shows the MR ratio at the heat treatment temperature. In the sample C of the example, the MR ratio at the time of film formation was 35%.
A large MR ratio of 37% was obtained. Moreover, even if the heat treatment was performed up to 400 ° C, the MR ratio could be obtained almost stable. On the other hand, in the conventional sample D, the MR ratio was as low as 20% during film formation, but when the heat treatment was performed up to 250 ° C., the MR ratio was improved to 25%. The improvement of MR ratio by this heat treatment is due to the tunnel insulating layer (Al-O).
And the ferromagnetic layer (Co-Fe) interface is smoother than at the time of film formation. However, when the temperature is further increased and heat treatment is performed, the MR ratio decreases.
Only 2% could be obtained at 0 ° C. Therefore, it was found that the sample C of the example prepared by the method for manufacturing the tunnel insulating layer of the present invention has a high MR ratio and high heat resistance.

[0047]

[Table 1]

In this embodiment, the time for plasma-oxidizing Al (1.2 nm) in the process of forming the tunnel insulating layer 12 was set to 60 seconds, but the examination was conducted by changing the oxidation time from 20 seconds to 600 seconds. The same result was obtained, and it was found that it is not the difference in the characteristics due to the oxidation condition of Al (1.2 nm) but the characteristic result depending on the film forming rate of Al. Furthermore, similar results could be obtained by forming the tunnel insulating layer 12 by plasma oxidation and radical oxidation.

(Example 3) As an embodiment of the present invention,
The pinned magnetic layer shown in FIG. 4 has a laminated ferri structure.
A method of manufacturing a valve type TMR element will be shown. Similar to Example 1
The ultimate vacuum is 1 × 10 depending on the experimental conditions.^-8Deposition below Torr
D on a Si substrate with a thermal oxide film of 500 nm in the chamber
Fabrication of TMR film by C and RF magnetron sputtering method
did. First, Ta (3nm) / Cu (50n
m) / Ta (3nm) / Ni_0.56Fe_0.14Cr_0.3 (4 nm) was laminated. So
Pt-Mn (20 nm) of the antiferromagnetic layer 14 and the ferromagnetic layer 11-
1 Co _0.75Fe_0.25(3 nm), Ru (0.8n) of the non-magnetic layer 11-2
m), Co of the ferromagnetic layer 11-3_0.75Fe _0.25(1nm) / Fe_0.85Pt
_0.15(2 nm) were sequentially laminated. Tunnel insulation layer 1 on it
2 was prepared by the following method. A at a deposition rate of 0.1Å / sec
1 (0.4 nm) was laminated. 10 to oxidize Al (0.4 nm)
^-8Via a transfer chamber that is evacuated below the Torr level
The substrate reaches the vacuum level of 1 x 10 from the deposition chamber.^-6Torr
Transport it to the following oxidation chamber and bring pure oxygen to 200 Torr
It is introduced until it is kept for 1 minute to oxidize Al (0.4 nm)
It was After exhausting oxygen, the substrate is transferred through the transfer chamber.
Is transferred to the deposition chamber and the deposition rate is 0.1Å / sec.
(0.3 nm) was laminated. Similar to oxidizing Al (0.4 nm)
After transporting the substrate to the oxidation chamber, add pure oxygen to 200 Torr
And keep it for 1 minute to oxidize Al (0.3 nm)
It was After exhausting oxygen, transfer the substrate to the deposition chamber
Then, Al (0.3 nm) was laminated at a film forming rate of 0.1 Å / sec. Board
Pure oxygen reaches 200 Torr after being transported to the oxidation chamber
And hold for 1 minute to oxidize Al (0.3nm)
A flannel insulating layer 12 was created. Next to the deposition chamber substrate
Of the second ferromagnetic layer 13_0.85Pt
_0.15(2nm) / Ni_0.8Fe_0.1(5 nm) is deposited and the TMR element part is created.
I made it. The film composition of the TMR element part is Pt-Mn (20nm) / Co-Fe (3
nm) / Ru (0.8nm) / Co-Fe (1nm) / Fe-Pt (2nm) / Al-O
(0.4nm) / Al-O (0.4nm) / Al-O (0.3nm) / Fe-Pt (2nm) /
 It was Ni-Fe (5 nm). As a protective layer and part of the upper electrode
Form Ta (10nm) / Pt (50nm) to make the basic film structure of TMR element.
Made This sample is referred to as Example Sample E.

Ar is used as the sputter gas, and the Ar gas is 0.8 mTorr.
All layers were formed by gas pressure. Here, Ta, Cu, Pt, Pt-Mn, Co _0.75 Fe _0.25 , Fe _0.85 Pt are used for forming each layer.
_{0.15, Ni 0 .56 Fe 0.14 Cr} 0.3, using Ru as a target was performed at a deposition rate of 0.4～1A / sec.

Further, a film structure similar to the method of preparing the sample E of the embodiment is used.
The method of creating the tunnel insulating layer 12 is described below.
Example sample F prepared by the method described below was prepared. Tons
As a method for forming the flannel insulating layer 12, Co of the ferromagnetic layer 11-3 is used.
_0.75Fe_0.25(1nm) / Fe_0.85Pt _0.15The deposition rate on (2 nm) is
Laminate an Al (1.0 nm) layer at 0.1 Å / sec and place it in the oxidation chamber.
Convey the plate, Ar: O₂= 1: 4 mixed gas with 100 Torr
And then hold at room temperature for 10 minutes
The tunnel insulating layer 12 (Al-O (1.0n
m)) was created.

The films of the samples E and F of this example were subjected to the element processing step shown in FIG. 6 to prepare a TMR element as shown in FIG.
Similar to the first embodiment, the upper electrode portion 502 is processed in the step of FIG.
As a film, Ta (5nm) / Cu (500nm) / Pt (50nm) / Ta (5nm) was deposited. TMR element size is 1 μm × 1 μm to 50 μm × 50 μ
m. After processing the device, a magnetic field of 5 kOe was applied to the surface of the film to order PtMn and generate exchange coupling, and heat treatment was performed in the magnetic field at 280 ° C. for 5 hours. After the heat treatment, the magnetic resistance was measured at room temperature by the DC four-terminal method. The magnetic field application direction is parallel to the magnetic field direction applied during the heat treatment. 280
The MR ratio of the sample of the example sample E after the heat treatment at 42 ° C. is 42%, and the MR ratio of the sample of the example sample F is 40% (the element size of the example samples E and F is 2 μm × 6 μm. Although shown, almost the same MR characteristics were obtained for other device sizes). The samples E and F of this example were heat-treated at 400 ° C. in vacuum. Four
The holding time at 00 ° C was 30 minutes. After that, when the magnetic resistance was measured at room temperature, the MR ratios of the example samples E and F were respectively
In both samples, 45% and 44%, the MR ratio increased slightly after the heat treatment at 280 ℃. Furthermore, when the heat treatment was also performed at 400 ° C. for a holding time of 30 minutes and the MR was measured at room temperature, the MR ratio remained stable in both samples.
We were able to obtain MR characteristics. Next, when the bias voltage dependence of the MR ratio of both samples subjected to the heat treatment at 400 ° C. twice was examined, the voltages at which the MR ratio became half were 550 mV and 570 mV for the example samples E and F, respectively. . As a comparative example, the bias voltage dependence of the MR ratio of the conventional sample B prepared in Example 1 and the conventional sample D prepared in Example 2 was examined. Here, as the conventional sample B, the sample after the heat treatment at 280 ° C. was used, and as the conventional sample D, the sample after the heat treatment at 250 ° C. was used. MR
The voltage at which the ratio is halved is 380 mV for the conventional sample B and 400 mV for the conventional sample D, and it was found that the MR ratio decreased with a voltage smaller than those of the samples E and F of this example. Therefore, excellent heat resistance can be obtained by using the method for forming a tunnel insulating layer of the present invention and the use of the first ferromagnetic layer (Fe-Pt) and the second ferromagnetic layer (Fe-Pt) adjacent to the tunnel insulating layer. It has been found that it is possible to provide a TMR device with high bias voltage characteristics.

(Example 4) As an embodiment of the present invention,
A method of manufacturing the dual spin valve type TMR element shown in FIG. 5 will be described. Under the same experimental conditions as in Example 1, the ultimate vacuum degree was 500 nm in a film forming chamber with a vacuum of 1 × 10 ⁻⁸ Torr or less.
A TMR film was prepared on the Si substrate with thermal oxide film by DC and RF magnetron sputtering method. First, Ta (3 nm) / Cu (50 nm) / Ta (3 nm) was laminated as the lower electrode 20 on the substrate. The dual spin valve type TMR shown in FIG.
The element part was created. Pt-Mn (20n of the first antiferromagnetic layer 30
m), Co _0.75 Fe _0.25 (2 nm) / Fe _{0.70 of} the first ferromagnetic layer 31
Ni _0.15 Pt _0.15 (2 nm) is laminated to form the first tunnel insulating layer 3
2 is an experimental condition similar to that of the sample E of Example 3 (Al film forming rate: 0.1 Å / sec, oxidation of the Al layer is at an oxygen gas pressure of 200 Torr for 1 minute), and Al-O (0.4 nm) / Al-O (0.3nm) / Al-O (0.3
(nm) tunnel insulating layer was created. Fe _0.70 Ni _0.15 Pt _0.15 (1nm) / Ni _0.8 Fe _0.2 (3n
m) / Fe _0.70 Ni _0.15 Pt _0.15 (1 nm) was laminated, and the second tunnel insulating layer 34 was formed to have the same film thickness as the first tunnel insulating layer 33 under the same experimental conditions. Fe _0.70 Ni _0.15 Pt _0.15 (2nm) / Co _0.75 of the third ferromagnetic layer 35
Fe _0.25 (2 nm) on top of which Pt-Mn of the second antiferromagnetic layer 36
(20 nm) were laminated to form a dual spin valve type TMR element part. The film structure of the TMR element part is Pt-Mn (20nm) / Co-Fe
(2nm) / Fe-Ni-Pt (2nm) / Al-O (0.4nm) / Al-O (0.3nm)
/ Al-O (0.3nm) / Fe-Ni-Pt (1nm) / Ni-Fe (3nm) / Fe-Ni
-Pt (1nm) / Al-O (0.4nm) / Al-O (0.3nm) / Al-O (0.3nm)
/ Fe-Ni-Pt (2nm) / Co-Fe (2nm) / Pt-Mn (20nm). Therefore, there is a Fe-Ni-Pt layer containing Pt in Fe-Ni at both interfaces between the first and second tunnel insulating layers 32 and 34. Here, to create the Fe-Ni-Pt layer, Fe-Ni
The film was prepared by co-sputtering an alloy target and a Pt target so that the film composition was Fe _0.70 Ni _0.15 Pt _0.15 . After taking out the film created as described above into the atmosphere, it is introduced into the sputtering device attached to the reverse sputtering mechanism, and a part of the Ta protective layer is reverse-sputtered to flatten the surface and then used as the protective layer. Ta (10 nm) as part of the upper electrode
/ Pt (50 nm) was laminated. This sample is referred to as Example Sample G. As a comparative example, the film structure of the TMR element portion of the example sample G is Pt-Mn (20nm) / Co-Fe (4nm) / Al-O (1.0nm) / Ni-Fe.
(5 nm) / Al-O (1.0 nm) / Co-Fe (4 nm) / Pt-Mn (20 nm), part of the protective layer and upper electrode under the same experimental conditions except the tunnel insulating layer creation method A film up to (Ta / Pt) is referred to as a conventional sample H. Here, as a manufacturing method of the first tunnel insulating layer 32 (Al-O (1.0 nm)) and the second tunnel insulating layer 34 (Al-O (1.0 nm)) of the conventional sample H, 2.5 Å / Al layer of 1.0 nm stacked at a deposition rate of 2 seconds in an oxidation chamber to 200 To
It was created by spontaneous oxidation for 5 minutes at an oxygen gas pressure of rr.

The films of the sample G of the example and the sample H of the conventional example were subjected to the element processing steps shown in FIG. 6 to produce a TMR element as shown in FIG. Similar to the first embodiment, Ta (5nm) / Cu (500nm) / Pt (50nm) / Ta (5n) is used as the upper electrode portion 502 in the process of FIG.
m) was formed into a film. TMR element size is 1 μm × 1 μm to 50 μm
× 50 μm. After processing the device, a magnetic field of 5 kOe was applied to the surface of the film in order to order PtMn and generate exchange coupling.
Heat treatment was performed in a magnetic field for 5 hours at 0 ° C. After heat treatment,
The magnetic resistance was measured at room temperature by the DC four-terminal method. The magnetic field application direction is parallel to the magnetic field direction applied during the heat treatment.

After the heat treatment (280 ° C.), the MR ratio of the example sample G was 35%, and the MR ratio of the conventional sample H was 22% (the sample size of the example samples E and F was 5 μm × 5 μm). Although the MR ratio of is shown, MR characteristics are almost the same for other device sizes). Furthermore, these example sample G and conventional example sample H
Was subjected to heat treatment (320 ° C, 350 ° C, 400 ° C) in vacuum.
The holding time at each temperature was set to 30 minutes, and after each heat treatment, the magnetoresistance and the bias voltage were changed at room temperature to measure the magnetoresistance to examine the bias voltage dependence of the MR ratio. The results are shown in Table 2. In the example sample G, it was found that the MR ratio tended to increase slightly until the heat treatment temperature up to 400 ° C, but showed a substantially stable value, and even after the high temperature heat treatment at 420 ° C, the MR ratio was as high as 36%. Got the value. Furthermore, the bias voltage (V _h ) at which the MR ratio is halved is slightly improved by heat treatment, and 400 ° C
V _h showed a large bias characteristic of 850 mV. As described above, the sample G of this example produced according to the method for producing the tunnel magnetoresistive effect element of the present invention exhibited a high MR ratio and a high bias voltage resistance even after the high temperature heat treatment. On the other hand, in the sample H of the conventional example, the MR ratio decreases as the heat treatment temperature is increased, and Vh also decreases, and it is clear that the bias voltage characteristic is deteriorated as compared with the sample G of this example. The difference between the example sample G and the conventional example sample H is that the film forming rate of the Al layer as the tunnel insulating layer precursor is 0.1 Å / sec for G and 2.5 Å / sec for H, and , Fe-Ni- in the example sample G on the ferromagnetic layer adjacent to the tunnel insulating layer.
The layered structure containing Pt and Pt is considered to be the reason why the MR ratio and the bias voltage characteristic of the sample G of the example are better than those of the sample H of the conventional example.

[0056]

[Table 2]

[0057]

As described above, by using the manufacturing method of the present invention in the manufacturing method of the tunnel magnetoresistive effect element, it is possible to form a tunnel insulating layer which is homogeneous and has excellent insulating characteristics, and which has a high output. It is possible to provide a tunnel magnetoresistive effect element excellent in high heat resistance. Further, it is possible to provide a high-density magnetic head or a high-density nonvolatile random magnetic memory (MRAM) as a magnetic device using the tunnel magnetoresistive effect element manufactured by the manufacturing method of the present invention.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a process of manufacturing a tunnel magnetoresistive effect element of the present invention.

FIG. 2 is a schematic view of a cross section in which electrodes are arranged above and below a tunnel magnetoresistive element manufactured by the manufacturing method of the present invention.

FIG. 3 is a schematic view of a cross section of a spin-valve tunnel magnetoresistive effect element manufactured by the manufacturing method of the present invention.

FIG. 4 is a schematic cross-sectional view of a spin-valve tunnel magnetoresistive effect element having a laminated ferri pinned magnetic layer produced by the manufacturing method of the present invention.

FIG. 5 is a schematic cross-sectional view of a dual structure spin-valve tunnel magnetoresistive effect element manufactured by the manufacturing method of the present invention.

FIG. 6 is a schematic view illustrating a processing step of a TMR element manufactured by the manufacturing method of the present invention.

FIG. 7 is a sectional view of a TMR element produced by the manufacturing method of the present invention.

FIG. 8 is a diagram showing an example of a magnetic memory element using a TMR element manufactured by the manufacturing method of the present invention.

FIG. 9 is a diagram showing a basic example of a write operation and a read operation of a magnetic memory element using a TMR element produced by the manufacturing method of the present invention.

FIG. 10 is a diagram showing a basic example of a write operation and a read operation of a magnetic memory element using a TMR element manufactured by the manufacturing method of the present invention.

FIG. 11 is a diagram showing a basic example of a write operation and a read operation of a magnetic memory element using a TMR element produced by the manufacturing method of the present invention.

FIG. 12 is a diagram showing an example of a shield type magnetoresistive head using a TMR element produced by the manufacturing method of the present invention.

FIG. 13 is a diagram showing an example of a yoke type magnetoresistive head using a TMR element produced by the manufacturing method of the present invention.

FIG. 14A is a diagram illustrating a tunnel magnetoresistive effect. (B) Diagram explaining the tunnel magnetoresistive effect (C) Diagram showing a magnetic resistance curve

FIG. 15 is a schematic diagram showing the cross-sectional structures of the films of Example sample A and Conventional example sample B created in Example 1.

[Explanation of symbols]

10 TMR element part 11 First ferromagnetic layer 12 Tunnel insulation layer 13 Second ferromagnetic layer

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 27/105 H01L 43/08 Z 43/08 27/10 447 G01R 33/06 R (72) Inventor Akihiro Odagawa Osaka Prefecture 1006 Kadoma, Kadoma-shi, Matsushita Electric Industrial Co., Ltd. (72) Inventor Yoshio Kawashima, 1006 Kadoma, Kadoma, Osaka Prefecture (72) Inventor, Matsushita Electric Industrial Co., Ltd. Sangyo Co., Ltd. (72) Inventor Yasunori Morinaga 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 2G017 AA10 AD55 5D034 BA03 BA15 BA18 CA02 DA07 5E049 AA01 AA04 AA07 BA12 5F083 FZ10 JA36 JA37 JA38 JA39 JA40 PR01 PR04 PR22

Claims (12)

[Claims] 1. A first ferromagnetic layer, a tunnel insulating layer, and a second ferromagnetic layer are laminated in this order on a substrate, and the magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer are different from each other. In a tunnel magnetoresistive effect element having different tunnel magnetoresistance due to a difference in relative angle, a first step of forming a conductive layer which is the tunnel insulating layer precursor, and a second step of oxidizing the conductive layer in an oxygen atmosphere. In the first step, the conductive layer contains Al, Mg, S at a film forming rate of 0.4 Å / sec or less.
A method for manufacturing a tunnel magnetoresistive effect element, which is formed of at least one of i and Ta. 2. The method for manufacturing a tunnel magnetoresistive element according to claim 1, wherein the tunnel insulating layer is formed by performing the first step and the second step a plurality of times. 3. The conductive layer formed in the first step comprises:
The method of manufacturing a tunnel magnetoresistive effect element according to claim 1, wherein the second step is a step of oxidizing in a vacuum. 4. The method of manufacturing a tunnel magnetoresistive element according to claim 1, wherein the conductive layer formed in the first step has a film thickness of 4 nm or less. 5. The method of manufacturing a tunnel magnetoresistive element according to claim 3, wherein the conductive layer is oxidized by a natural oxidation method. 6. A method of manufacturing a tunnel magnetoresistive effect element, wherein the method of oxidizing the conductive layer according to claim 3 is a plasma oxidation method. 7. A method for manufacturing a tunnel magnetoresistive effect element, wherein the method for oxidizing a conductive layer according to claim 3 is a radical oxidation method. 8. The method according to claim 1, further comprising a third step of forming the first ferromagnetic layer and a fourth step of forming the second ferromagnetic layer. A method for manufacturing the tunnel magnetoresistive effect element described. 9. The first ferromagnetic layer or the second ferromagnetic layer
2. At least one of the ferromagnetic layers of Fe is a main component of at least one of Fe, Co, and Ni, and further contains at least one of Pd, Pt, Ir, Rh, and Ru.
9. A method for manufacturing a tunnel magnetoresistive effect element according to any one of 1 to 8. 10. A magnetoresistive head including a tunnel magnetoresistive element manufactured by the manufacturing method according to claim 1 and further including a shield portion. 11. A magnetoresistive effect element comprising the magnetoresistive effect element produced by the manufacturing method according to claim 1 and further comprising a yoke for introducing a magnetic field to be detected into the magnetoresistive element section. head. 12. A magnetoresistive effect element portion manufactured by the manufacturing method according to claim 1, further comprising an information reading conductor line (sense line) portion for further reading information, and a data recording portion. A magnetoresistive effect memory device comprising an information recording conductor wire (word wire portion).