JP2002299724A - Magnetoresistance effect element and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetoresistance effect element which is formed by suppressing as much as possible, the usage of etching method using physical sputtering such as ion milling method or the like, and to provide its manufacturing method. SOLUTION: A magnetoresistance effect element 31 is accumulated and formed in a recessed part 21a of an insulation film 21, formed on a lower electrode 11 by using the collimation method. The recessed part 21a is formed by isotropically etching the insulation film 21, while using a hard mask with a formed opening. After the recessed part 21a use been filled with a second insulation film 41, first and second insulation films are etched back flat, and a contact metal of the magnetoresistance effect element 31 is exposed, and then an upper electrode 51 is formed thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an information reproducing technique using a ferromagnetic material, and more particularly to a giant magnetoresistive element, a ferromagnetic tunnel effect element and a method of manufacturing the same.

[0002]

2. Description of the Related Art Magnetic random access memory (Magnetic)
Random Access Memory (MRAM)
Utilizing the magnetization direction of ferromagnetic material as information record carrier,
This is a general term for solid-state memories that can rewrite, hold, and read recorded information as needed.

An MRAM memory cell usually has a structure in which a plurality of ferromagnetic materials are stacked. Recording of information is performed in accordance with the binary information "1" and "0" whether the relative arrangement of the magnetizations of the plurality of ferromagnetic materials constituting the memory cell is parallel or antiparallel. Writing of recorded information is performed by reversing the magnetization direction of the ferromagnetic material of each cell by a current magnetic field generated by applying a current to a write line arranged in a cross stripe. This is a non-volatile memory in which the power consumption during recording and holding is zero in principle, and the recording and holding are performed even when the power is turned off. Reading of recorded information is a phenomenon in which the electrical resistance of a memory cell changes according to the relative angle between the magnetization direction of a ferromagnetic material constituting the cell and the sense current, or the relative angle of magnetization between a plurality of ferromagnetic layers, a so-called magnetoresistance. Use the effect.

[0004] The MRAM is compared with a conventional semiconductor memory using a dielectric material in terms of its function. (1) It is completely non-volatile and can be rewritten 10 ¹⁵ times or more. (2) Nondestructive reading is possible, and a refresh operation is not required, so that the read cycle can be shortened. (3) It has many advantages such as higher resistance to radiation as compared with charge storage type memory cells.

It is expected that the degree of integration per unit area of the MRAM, and the writing and reading times may be substantially the same as those of the DRAM. Therefore, taking advantage of the great feature of non-volatility, it is expected to be applied to external recording devices for portable devices, LSI embedded applications, and further to main memory memories of personal computers.

MRA currently being studied for practical use
In M, the ferromagnetic tunnel effect (Tunnel Mag
neto-Resistance: An element exhibiting the TMR effect is used (for example, ISSCC 2000 Digest Paper pp.
128-131). An element exhibiting the TMR effect (hereinafter abbreviated as a TMR element) is mainly composed of a three-layer film composed of a ferromagnetic layer / insulating layer / ferromagnetic layer, and a current flows through the insulating layer by tunneling.

The tunnel resistance changes in proportion to the cosine of the relative angle between the magnetizations of the two ferromagnetic metal layers, and takes a maximum value when the magnetizations are antiparallel. For example, NiFe / Co / Al ₂ O ₃ /
In a Co / NiFe tunnel junction, a magnetoresistance ratio exceeding 25% has been found in a low magnetic field of 50 Os or less (see, for example, IEEE Trans. Mag., 33, 3553 (1997)).

The structure of the TMR element has a so-called spin valve structure in which an antiferromagnetic substance is arranged adjacent to one ferromagnetic substance and the magnetization direction is fixed (for example, Jpn. J. Appl. Phys., 36, L200 (199
7), and a double tunnel barrier is provided to improve the bias dependence of the magnetoresistance ratio (for example, Jpn. J. Appl. Phys., 36, L1380 (1)
997)).

For the fine processing of the TMR element portion, a processing process using both photolithography and ion milling using Ar ions is generally used. However, ion milling is a physical sputtering method,
There is a disadvantage that the material to be processed is reattached as a residue as a result of processing to the side surface of the resist mask or the processing apparatus.

At present, in the field of semiconductors, chemical dry etching (hereinafter abbreviated as CDE),
A dry etching method using a chemical reaction such as reactive ion etching (hereinafter abbreviated as RIE) is actively used. S using chemical reaction
In the etching of i, SiO ₂ or the like, the workpiece is removed as a halide having a high vapor pressure in a gas phase.
However, Fe, Ni, C used for the TMR element
Halides of 3d transition metals such as o and Cu have low vapor pressures, and it is difficult to apply the process used for semiconductor processing as it is.

A method has been devised in which a mixed gas of carbon monoxide and ammonia is used to form an organometallic compound and perform chemical etching (for example, see Journal of the Japan Society of Applied Magnetics, Vol. 22, p. 1383). In addition, the chemical reaction rate is insufficient, and there is a problem that the process must be a process in which physical spattering by the reaction gas is mixed.

In recent years, in the manufacturing process of DRAMs, MPUs, and the like, Cu wirings are often used in place of conventional Al wirings for the purpose of reducing wiring delay, improving electromigration resistance, and improving heat dissipation. As described above, it is difficult to chemically etch Cu with a halogen-based reaction gas used for etching Al.

Therefore, a buried wiring forming technique (damascene method) has been proposed as a method completely different from the conventional method of processing a wiring, depositing an interlayer insulating film, and flattening (for example, IEEE Electron Device). Lett. Vol. 14, No.3
pp.129-131). This is because, after forming a trench to be a wiring portion in an interlayer insulating film in advance, a wiring film of Cu or the like is entirely formed, and a chemical mechanical polishing method (Chemical Mechanica) is used.
l Polishing (hereinafter abbreviated as CMP method) and the like to realize wiring separation by flattening. Further, a dual damascene method is known in which not only the wiring but also the connection hole to the lower wiring is simultaneously filled with a metal film.

These damascene methods are mainly applied to passive elements such as wiring and connection holes. As an example of application to an active element, for example, a damascene gate structure transistor in which a gate portion of a MOS transistor is formed by a damascene method is known. However, a manufacturing method using a damascene method for a memory element portion is not known at present.

On the other hand, when the TMR element is applied to an MRAM, it is necessary to connect electrodes at both ends to external circuits such as a data line and a selection transistor. In particular, since the TMR element has a vertical structure, when the upper electrode is connected to an external wiring, element isolation by an insulating film is indispensable.

A contact hole for wiring connection is formed in the insulating film. The contact holes can be formed by (1) etching the insulator by reactive chemical etching using a resist mask, (2) forming an insulating film while leaving the resist used for device processing, and then using a solvent or the like. Stripping of resist (self-alignment process) is mainly used.

However, in the method (1), the mask alignment margin in this step defines the minimum processing size of the element, and there is difficulty in miniaturization. In the method (2), miniaturization progresses, When the thickness of the photoresist and the element dimensions are almost the same, there are disadvantages such as difficulty in removing the resist.

[0018]

As described above, the conventional M
As a fine processing method of a magnetoresistive element used for a RAM or the like, photolithography and an ion milling method using Ar or the like have been mainly used. However, in the ion milling method, which is a physical sputtering method, the material to be processed is left as a residue with the processing, and the resist mask side surface,
In addition, they have the disadvantage that they re-adhere to the processing equipment and cause deterioration of the characteristics of the element and a decrease in the yield.

SUMMARY OF THE INVENTION The present invention has been made to address such problems, and minimizes the use of an etching method by physical sputtering, such as an ion milling method, and provides a magnetoresistive element having new structural advantages. It is intended to provide.

[0020]

SUMMARY OF THE INVENTION The present invention relates to a GMR (Gian
t Magneto-resistance), TMR (Tunneling Magneto-resistance)
resistance) A magnetic element structure capable of minimizing the use of an etching method by physical sputtering such as an ion milling method in a manufacturing process of a magnetic element portion of an MRAM using an element, and a method of manufacturing the magnetic element. .

The magnetoresistive element of the present invention has a first insulating layer formed on the surface of a lower electrode, an opening formed on the first insulating layer and reaching the surface of the lower electrode, A magnetoresistive film connected to the lower electrode formed apart from the side wall of the opening, a second insulating layer formed between the side wall of the opening and the magnetoresistive effect film, And an upper electrode connected to the film.

The method for manufacturing a magnetoresistive element of the present invention comprises:
Preparing a lower electrode in which a first insulating layer and a hard mask layer are stacked in this order, forming an opening in the hard mask layer,
The first insulating layer is selectively removed by isotropic etching using the hard mask layer in which the opening is formed as a mask until the first insulating layer reaches the lower electrode, and the upper surface of the lower electrode exposed through the opening is removed. Forming a magnetoresistive film,
A second insulating film is deposited in the concave portion of the first insulating film to fill the magnetoresistive film, and the first and second insulating films are planarized until the upper electrode of the magnetoresistive film is exposed. Removing the upper electrode to be connected to the upper contact electrode of the magnetoresistive film.

According to another method of manufacturing a magnetoresistive element of the present invention, a lower electrode having a first insulating layer formed on an upper surface is prepared, and a plane substantially reaching the lower electrode is provided on the first insulating layer. A trench having a closed structure is formed therein, a ferromagnetic film is buried in the trench, and the first insulating layer surrounded by the ferromagnetic film is selectively removed to expose an upper surface of the lower electrode. Forming an opening, forming a magnetoresistive film on the upper surface of the lower electrode exposed through the opening, depositing a second insulating film through the opening, and exposing the upper contact electrode of the magnetoresistive film. Up to the first and second
The insulating film and the ferromagnetic film are planarly removed to form an upper electrode connected to the upper contact electrode of the magnetoresistive film.

According to still another method of manufacturing a magnetoresistive element of the present invention, a first insulating layer is formed on a lower electrode,
Two grooves substantially reaching the lower electrode in a predetermined cross section are formed in the first insulating layer, a ferromagnetic film is embedded in the two grooves, and the first insulating layer sandwiched between the two grooves is formed. Selectively removing to form an opening reaching the upper surface of the lower electrode, forming a magnetoresistive film on the upper surface of the lower electrode in the opening, forming a side wall of the magnetoresistive film and a side wall of the opening; A second insulating layer is formed between the first and second insulating layers, and after the upper surfaces of the magnetoresistive film and the first and second insulating layers are made substantially flush with each other, an upper electrode connected to the magnetoresistive film is formed. It is characterized by the following.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In any of the magnetoresistive film elements described in the preceding paragraph, the magnetoresistive film element formed in contact with the side wall of the opening and spaced apart from the magnetoresistive film is larger than the magnetoresistive film. Either a ferromagnetic film having a coercive force or a ferromagnetic film having a higher magnetic permeability than the magnetoresistive film can be further provided.

Preferred embodiments of the present invention are as follows. (1) The magnetoresistive effect film has one layer of tunnel barrier or non-magnetic layer, and one side of one tunnel barrier or non-magnetic layer and a ferromagnetic alloy or a multilayer film containing Fe, Ni, Co and PtM
n, a pinned layer in which a high coercivity layer containing at least one antiferromagnetic thin film is laminated, and Fe, Ni, Co on the other end.
A spin-valve structure in which a recording layer comprising a ferromagnetic alloy or a multilayer film containing

(2) The magnetoresistive film has two layers of tunnel barrier or non-magnetic layer, and a ferromagnetic alloy or a ferromagnetic multilayer film containing Fe, Ni and Co on both sides of the tunnel barrier or non-magnetic layer. A pinned layer in which a high coercivity layer containing at least one antiferromagnetic thin film such as PtMn is laminated, and a ferromagnetic alloy or multilayer containing Fe, Ni, and Co as an intermediate layer sandwiched between tunnel barriers. A dual spin valve structure in which a recording layer is disposed.

(3) As the insulating film formed on the lower electrode, SiO ₂ , SiO, HSQ (hydrogen sisesquiox) may be used.
ane), MSQ (methylsesquioxane), phosphorus-doped glass, Al ₂ O ₃ , and Si ₃ N ₄ are suitable, but the material type is not limited as long as it has an insulating function. In view of reducing the capacitance between wirings, a low dielectric constant material is preferable.
As the film forming method, a sputtering method, a CVD method, a coating method and the like are suitable, but the method is not particularly limited.

(4) As a method for selectively removing the insulating film on the wiring, CDE and RIE using a halogen-based gas and a fluorocarbon-based gas are appropriate. And the reactive gas species are not limited. However, in order to reduce the dimensional conversion difference with respect to the element region, it is preferable to use an etching method which has a characteristic capable of etching a concave portion with a high aspect ratio. As a mask at the time of etching, in addition to a mask using an organic molecular polymer, a hard mask made of a metal or a dielectric to which a pattern is transferred by a so-called lift-off method may be used. For pattern transfer onto the mask, a conventionally known lithography technique such as photolithography or electron beam drawing may be used.

(5) As a method for forming a magnetoresistive film on the lower electrode having the concave portion formed therein, a sputtering method, a vapor deposition method,
A vapor phase growth method such as a CVD method is suitable. In order to realize the flat embedding in the concave portion, a method obtained by improving the prior art such as a long throw sputtering method and a collimated sputtering method is appropriate. In any case, details of the method are not limited as long as the method has a film forming action and a flat filling action in the concave portion.

The use of a laminated film made of a plurality of metals and alloys for the magnetoresistive effect film is a preferred mode from the viewpoint of improving the function of the element. Regarding the formation of a magnetoresistive film composed of these different types of materials, it is desirable to select and use an optimal formation method as appropriate.

(6) The CMP method is optimal as a method for removing a part of the magnetoresistive film and the insulating film and leaving the material film in the concave portion to perform element isolation. The polishing agent, polishing conditions, end point detection method and the like at that time are not limited by the present invention. In addition, if it is a method having the action, CMP
In addition to the method, a method such as an etch-back method and a chemical removal method is also possible.

(7) After element isolation, an optional step may be additionally provided before the step of forming the upper wiring.

In the magnetoresistive element of the present invention, it is possible to minimize the use of etching by physical sputtering such as ion milling in the manufacturing process. Therefore, it has the following excellent features.

(1) In the etching by physical sputtering, a substance to be processed is attached to a wafer and a processing apparatus as a residue as a result of the processing. These are undesirable because they cause deterioration of wafer characteristics and yield. In the case of a vertical type magnetoresistive element, reattachment to the side surface of the element causes fatal damage to element characteristics. In the present invention, it is possible to eliminate such a problem relating to the reattachment as much as possible.

(2) In an etching process by physical sputtering, in order to reduce reattachment to the vicinity of the element, a method of injecting an ion beam used for sputtering at an angle with respect to a substrate normal line is often used. However, in such ion beam etching by oblique incidence, the element side angle after processing has a taper angle of several tens degrees. Further, since the side surface angle changes depending on the beam incident angle, the mask side surface inclination, and the mask thickness, a dimensional conversion difference differs depending on the process. Since the resistance value of the magnetoresistive film depends on the bottom area of the film, the variation in the dimensional conversion difference directly leads to the variation in device characteristics. In the present invention, since the element region can be accurately defined by CDE, RIE, or the like, such a characteristic variation can be eliminated.

(3) When a magnetoresistive film is processed by an etching method involving charged particles such as an ion milling method, electrostatic breakdown of an insulating film portion causes deterioration of device characteristics. In the present invention, since the processing involving charged particles can be eliminated as much as possible from the processing of the magnetoresistive element, such a problem can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a sectional view schematically showing a peripheral portion of a magnetoresistive element according to a first embodiment of the present invention. In the drawing, reference numeral 10 denotes a base insulating layer, 11 denotes a lower electrode, 21 denotes a first insulating layer, 31 denotes a magnetoresistive film formed of a laminated film described later, 41 denotes a second insulating layer, and 51 denotes an upper electrode. As shown in the figure, in the magnetoresistive element of the present embodiment, the magnetoresistive film 31 is formed in the first insulating layer 21 and is formed in the concave portion 21 a reaching the surface of the lower electrode 11. The magnetoresistive film 31 includes the lower electrode 11 and the upper electrode 51.
Are electrically connected to each other, and a current flows in a direction perpendicular to the film surface.

The recess 21a is filled with a second insulating layer 41. The size of the bottom surface of the recess 21 a is substantially equal to the size of the magnetoresistive film 31. Also, the first insulating layer 11
And the upper surface of the second insulating layer 41 are on the same plane, and also coincide with the bottom surface of the upper electrode 51.

Next, a method of manufacturing the magnetoresistive element of this embodiment will be described in detail with reference to FIGS. FIG. 2 is a sectional view schematically showing a manufacturing process of the magnetoresistive element according to the first embodiment of the present invention.

First, the lower electrode 11 on the base insulating layer 10
(Ti (5 nm) / TiN (5 nm) / Ta (20 n
m) to a thickness of 200 nm so as to cover the
SiO _TwoPlasma insulating layer 21 made of
It is deposited by the method. After that, a 10 nm thick non-sensitive
The optical resin layer 22 is spin-coated, and further has a film thickness of 100 n.
m Si₃N₄Hard mask layer 23 made of
It is deposited by the method. In addition, application and exposure of photoresist 24
Embedded part in photoresist 24 by light and development process
Is formed (FIG. 2A).

Next, the hard mask layer 23 is formed by RIE using a fluorocarbon-based reaction gas, for example, a mixed gas of C ₄ F ₈ and CO, and then the non-photosensitive resin layer 22 is formed by RIE using O ₂ gas. Etching is performed until the first insulating layer 21 is reached. As mentioned in this example, the hard mask layer 2
In order to form the openings 23a, 22a in the third insulating film 22 and the non-photosensitive resin layer 22, it is preferable to combine a material and a reactive gas that can obtain a sufficient selection ratio with the first insulating film 21. After the etching, the photoresist 24 is removed by a solvent (FIG. 2B).

Next, the first insulating layer 21 is etched by using a mixed gas of CF ₄ + H ₂ until reaching the lower electrode 11 using a down-flow type CDE apparatus. Here RIE
Is not used in order to cause the etching reaction to be performed isotropically.
A wine cup-shaped recess 21a is formed as shown in FIG. This shape is because the reaction proceeds concentrically from the opening. In order to form the concave portion 21a, it is preferable to combine a material and a reactive gas that can obtain a sufficient selectivity between the first insulating layer 21 and the lower electrode 11.

After opening the concave portion 21a in the first insulating layer 21,
This sample is mounted on a vacuum device (not shown) for film formation,
Cleaning with Ar ions is performed for surface cleaning. In the present embodiment, a tunnel magnetoresistive film is used as the magnetoresistive film 31.
Was used for film formation using an ultra-high vacuum sputtering apparatus equipped with a collimator. The distance between the sputter target and the wafer is about 40 cm apart, realizing so-called long throw sputtering.

In this embodiment, as shown in FIG. 3A, the opening 23a of the hard mask layer 23 functions as a collimator for incident sputtered particles. Since the characteristics of the collimator change depending on the ratio between the opening size and the film thickness, it is possible to control the deposited shape of the magnetoresistive film by controlling the opening size and the film thickness. It is a great advantage of the present invention that the element structure in the manufacturing process has a collimating function.

The lower electrode 301 of the magnetoresistive film 31 is N
iFe (5 nm) / PtMn (10 nm) / Co (3n
m), and the upper electrode 303 is made of Co (3 nm).
It consisted of a single layer film, and each was deposited by a sputtering method.
The junction barrier 302 is made of amorphous Al ₂ O ₃ ,
After depositing Al with a thickness of 1 nm by a sputtering method, it was formed in contact with oxygen plasma. After the deposition of the upper electrode 303, Ta having a thickness of 50 nm was further deposited as a contact metal 304 by a sputtering method (FIG. 3A).

Then, the hard mask layer 23 and the deposits 31 '(301 to 304) on the hard mask are removed by dissolving the resin layer 22 using a solvent (FIG. 3B). The deposit 31 'is a laminated film having the same layer structure as that deposited at the same time as the formation of the magnetoresistive film 31.

After that, first, a 500 nm-thick Al ₂ O ₃ is deposited as a _second insulating layer 41 on the entire surface, and the magnetoresistive film 31 is completely covered. Then, a flattening resist (not shown) +
The whole is etched until it reaches the contact metal 304 of the magnetoresistive effect film 31 by etch back using RIE and CMP. In the present embodiment, the upper portion of the contact metal 304 is not formed beyond the first insulating layer 21. Thereby, a structure in which the upper surfaces of the first insulating layer and the second insulating layer are on the same plane, which is a feature of the present invention, is formed (FIG. 3C).

The upper electrode 51 is made of Ti (5 nm) / TiN
(5 nm) / Al (300) nm / TiN (5 nm). After being deposited over the entire surface by a sputtering method, a wiring pattern was formed by photolithography and RIE (FIG. 3D).

In this embodiment, the contact metal 304
By removing the second insulating layer 41 and the first insulating layer 21 until the contact reaches, the connection surface of the contact metal 304 is exposed in a self-aligned manner without forming a connection hole for a contact. That is, it is possible to omit the formation of the interlayer insulating film and the formation of the connection holes after the surface flattening by the conventional CMP method.

As in the present embodiment, the first insulating layer and the second
It is a great feature of the present invention that different materials can be used for the insulating layer. That is, the second insulating layer exists locally only near the magnetoresistive film, whereas the first insulating layer extends over the entire surface of the sample. Therefore, by optimizing each function according to the structure, it is possible to further improve the element function.

Combination of first insulating film and second insulating film
For example, the following can be considered. (1) First insulating layer: low dielectric constant material such as HSQ, second insulating layer
Edge layer: Si₃N₄, Al_TwoO_ThreeEtc. High density material. Near the magneto-resistance effect element, metal from the magneto-resistance effect element
Si to prevent diffusion _ThreeN_Four, Al_Two0_ThreeHigh density material
It is preferable to use But these materials have a dielectric constant
Is high, causing an increase in the capacitance between wirings. Follow
As in the present invention, a high-density high-permittivity material is
If low dielectric constant material is used for other parts,
Prevent degradation due to metal diffusion without compromising performance
It becomes possible.

(2) First insulating layer: low dielectric constant material such as HSQ, and second insulating layer: ferromagnetic insulating material such as ferrite.

In an element such as an MRAM in which a large number of magneto-resistive elements are integrated, magnetic interference between the magneto-resistive elements may cause a problem. In some cases, an external magnetic field acts as a disturbance as an environment in which the element is used. As a countermeasure, it is effective to dispose a soft magnetic material near the magnetoresistive element to have a function as a magnetic shield. For example, an oxide ferromagnetic material such as ferrite is suitable as such a magnetic shielding material.

However, since these materials have a high dielectric constant, they cause an increase in capacitance between wirings. Therefore, by using a ferromagnetic insulating material only in the vicinity of the element and using a low dielectric constant material in other parts as in the present invention, it is possible to prevent magnetic interference and disturbance without impairing the element performance. Become.

(Second Embodiment) FIGS. 4 and 5 are sectional views showing the steps of manufacturing a magnetoresistive element according to a second embodiment of the present invention step by step. The basic manufacturing process of this embodiment is the same as that of the first embodiment, and the same portions are denoted by the same reference numerals and detailed description thereof will be omitted.

A photoresist 24 having an opening 24a is formed on the hard mask layer 23 in the same manner as in the step of FIG. 2A of the first embodiment (FIG. 4A). Next, the hard mask layer 23, the resin layer 22, the first
An opening 24a 'penetrating through the green layer 21 and reaching the upper surface of the lower electrode 11 is formed (FIG. 4B).

When the first insulating layer 21 is isotropically etched in such a structure, the etched region becomes the opening 24a '.
From the outside, and as a result, the recess 21 having an opening size larger than the opening size of the hard mask layer 23.
a 'is formed (FIG. 5A).

Next, a magnetoresistive film 31 is formed using an ultra-high vacuum sputtering device equipped with a collimator device.
(B)) Thereafter, the resin layer 22 is taken out of the vacuum apparatus, the resin layer 22 is dissolved using a solvent, and the hard mask layer 23 and the deposit 31 ′ on the hard mask are removed (FIG. 5C).

Subsequently, the concave portion 21 a ′ is formed in the second insulating layer 41.
To etch back to the contact metal of the magnetoresistive film 31 (FIG. 5D). Then the upper electrode 5
By forming No. 1, the element structure shown in FIG. 5E is completed.

In the second embodiment, as described above,
Since 1a 'has a columnar structure, the boundary between the first insulating layer 21 and the second insulating layer 41 is substantially perpendicular to the film surface. The extent of the recess 21a 'can be controlled by the amount of etching at the opening of the recess.

(Third Embodiment) FIGS. 6 and 7 are sectional views showing the steps of manufacturing a magnetoresistive element according to a third embodiment of the present invention step by step. In the third embodiment, the basic manufacturing steps are the same as those of the first embodiment, and the same portions are denoted by the same reference numerals and detailed description thereof will be omitted.

In the third embodiment, the resin layer 22 is not provided between the first insulating layer 21 and the hard mask layer 23, and after the magnetoresistive film 31 is formed, the hard mask layer 23 and the deposit 31 thereon are formed. The feature is that the second insulating layer 41 is deposited without removing ′ (FIG. 7D). Hard mask layer 23
And the deposit 31 'are removed at the same time as the second insulating layer 41 is planarized (FIG. 7E).

In the third embodiment, a void 42 may be formed in the recess 21a when the second insulating layer 41 is deposited. In some cases, this can be solved by optimizing the deposition conditions of the second insulating layer 41. However, if there is no particular problem with the element function as shown in the figure, it can be left alone. In addition, before forming the upper electrode 51, the second insulating layer can be formed again over the entire surface and flattened to be removed.

(Fourth Embodiment) FIG. 8 is a sectional view schematically showing the structure of a magnetoresistive element according to a fourth embodiment of the present invention. In the figure, 11 is a lower electrode, 21 is a first electrode.
, 31 is a magnetoresistive film, 41 is a second insulating layer, and 51 is an upper electrode. Reference numeral 61 denotes a ferromagnetic film.

As shown in the figure, in the magnetoresistive element of the fourth embodiment, the magnetoresistive film 31 is formed on the first insulating layer 21, is surrounded by the ferromagnetic film 61, and has the lower electrode 11.
Is formed in a concave portion reaching the surface of the hologram. The magnetoresistive film 31 has a lower electrode 11. It is electrically connected to the upper electrode 21, and a current flows in a direction perpendicular to the film surface.

The recess is filled with a second insulating layer 41. The bottom area of the recess is formed substantially equal to the bottom area of the magnetoresistive film. Further, the upper surfaces of the first insulating layer 11 and the second insulating layer 41 and the upper surface of the ferromagnetic film 61 are on the same plane, and also coincide with the bottom surface of the upper electrode 51.

Next, a method of manufacturing the magnetoresistive element according to the third embodiment will be described in detail with reference to FIGS. 9 and 1
0 is an element cross-sectional view showing step by step the manufacturing process of the magnetoresistive element according to the fourth embodiment of the present invention.

First, the lower electrode 11 (T
i (5 nm) / TiN (5 nm) / Ta (20 nm))
A first insulating layer 21 made of SiO ₂ having a thickness of 200 nm is deposited by a plasma CVD method so as to cover (FIG. 9A). Further, thereafter, a trench having a closed structure in the film surface for embedding the ferromagnetic film 61 is opened in the first insulating layer 21, and the ferromagnetic film 61 is deposited and planarized as shown in FIG.
The structure shown in (b) is obtained.

Although the planar shape of the trench is not shown, it can be a desired shape such as a circle, a rectangle, or a parallelogram. The sectional shape of the trench is the same as that of the ferromagnetic film 61.
Preferably has a shape that can be sufficiently embedded, for example, a forward taper shape.

Further, two grooves almost reaching the lower electrode 11 in a predetermined cross section are formed in the first insulating layer 21, and a ferromagnetic film is buried in the two grooves and the first groove sandwiched between the two grooves is formed. The opening reaching the upper surface of the lower electrode 21 may be formed by selectively removing the insulating layer 21.

As the ferromagnetic film, for example, a CoPt alloy,
A hard magnetic alloy such as a Co / Pt multilayer film, a multilayer film, a multilayer film having strong interlayer coupling such as a Co / Cu multilayer film, a laminated film of an antiferromagnetic material such as PtMn and a hard magnetic alloy, or the like. Can be used. It is also possible to use a high magnetic permeability soft magnetic alloy such as a NiFe alloy or an amorphous alloy.

Next, an opening 24a for defining a buried portion in the photoresist 24 is formed by applying, exposing, and developing the photoresist 24 (FIG. 9C). Next, the first insulating layer 21 is etched until it reaches the lower electrode 11 by RIE using a fluorocarbon-based reaction gas, for example, a mixed gas of CF ₄ + H ₂ , and the recess 61 a surrounded by the ferromagnetic layer 61 is formed. Form. At this time, the first insulating layer 21
The ferromagnetic film 61 and the ferromagnetic film 61 need to have a sufficient selectivity with respect to the RIE reaction gas. As in the present embodiment, a combination of a ferromagnetic substance and SiO ₂ is preferable because a large selectivity exceeding 10 can be obtained by using a fluorocarbon-based reaction gas. Post-etch photoresist 2
4 is removed by a solvent (FIG. 9D).

In this embodiment, one direction of the dimension of the opening of the first insulating layer 21 is defined by the ferromagnetic film 61. That is, the processes of FIGS. 9B to 9D are self-alignment processes, and are not particularly affected by misalignment or dimensional conversion difference in the step of FIG. 9C. That is, it is possible to reduce the variation in the interval between the magnetoresistive element 31 and the ferromagnetic film 61, and the effect is large.

After the opening of the concave portion in the first insulating layer 21, this sample is mounted on a vacuum device for film formation, and cleaning with Ar ions is performed to clean the surface. In this embodiment, a tunnel magnetoresistive film is used as the magnetoresistive film 31. In the present embodiment, an ultra-high vacuum sbutter device having a collimator is used for film formation. The distance between the sputter target and the wafer is about 40 cm apart, realizing so-called long throw sputtering.

As shown, in this embodiment, the opening of the first insulating layer 21 defined by the ferromagnetic film 61 also functions as a collimator for incident sputtered particles. Since the characteristics of the collimator change depending on the ratio between the opening size and the film thickness, it is possible to control the deposited shape of the magnetoresistive film by controlling the opening size and the film thickness. It is a great advantage of the present invention that the element structure in the manufacturing process has a collimating function.

The lower electrode 301 is made of NiFe (5 nm) / P
a three-layer film composed of tMn (10 nm) / Co (3 nm),
The upper electrode 303 is made of a single-layer Co (3 nm) film, and each is deposited by a sputtering method. The junction barrier 302 is made of amorphous Al ₂ O ₃ , and is formed by depositing Al with a thickness of 1 nm by a sputtering method and then contacting it with oxygen plasma.
After the deposition of the upper electrode 303, the contact metal 30
As No. 4, Ta having a thickness of 50 nm was deposited by a sputtering method (FIG. 10A).

After the deposition of the magnetoresistive effect film 31, the second
After a 500 nm-thick Al ₂ O ₃ film is deposited as an insulating layer 41, and the magnetoresistive film 31 is completely covered (FIG. 10).
(B)), the entire surface is etched by the etch-back using the planarizing resist + RIE and CMP until reaching the contact metal 304 of the magnetoresistive film 31 (FIG. 1).
0 (c)).

In the third embodiment, the contact metal 3
The upper part 04 is not formed beyond the first insulating layer 21. Thereby, the first insulating layer 2 which is a feature of the present invention is provided.
A structure is formed in which the upper surfaces of the first and second insulating layers 41 and the ferromagnetic film 61 are on the same plane.
(c)).

The upper electrode 51 is made of T1 (5 nm) / TiN
(5 nm) / Al (300 nm) / TiN (5 nm), and after being deposited on the entire surface by a sputtering method, a wiring pattern is formed by photolithography and RIE (FIG. 10D).

In the third embodiment, as described above, the magnetoresistive film 3 is self-aligned with the region surrounded by the ferromagnetic film 61.
1, a structure in which a bias magnetic field is applied to the magnetoresistive film 31 can be realized.

(Fifth Embodiment) FIG. 11 shows a fifth embodiment of the present invention.
FIG. 4 is a cross-sectional view schematically illustrating a structure of a magnetoresistive element according to the embodiment. In the figure, 11 is a lower electrode, 21 is a first insulating layer, 31 is a magnetoresistive film, 41 is a second insulating layer,
51 is an upper electrode. Numerals 61, 62a and 62b are ferromagnetic films.

As shown in FIG. 11, in the magnetoresistive element of this embodiment, the magnetoresistive film 31 is
And is formed in a concave portion which is surrounded by the ferromagnetic film 61 and reaches the surface of the lower electrode 11. The magnetoresistive film 31 is electrically connected to the lower electrode 11 and the upper electrode 21, and a current flows in a direction perpendicular to the film surface. The recess is filled with a second insulating layer 41.

The bottom area of the recess is substantially equal to the bottom area of the magnetoresistive film. Further, the upper surfaces of the first insulating layer 21 and the second insulating layer 41 and the upper surface of the ferromagnetic film 61 are on the same plane and coincide with the bottom surface of the upper electrode 51.

The upper electrode 51 is covered on three sides by ferromagnetic films 62a and 62b.
b is connected to the ferromagnetic film 61 to form a magnetic circuit.
The ferromagnetic films 61, 62a, and 62b according to the present embodiment include a high-permeability soft magnetic alloy such as a NiFe alloy, for example.
Preferably, an amorphous alloy is used.

The fifth embodiment is characterized in that the upper electrode 51 has a so-called magnetic shield structure whose three surfaces are covered with ferromagnetic films 62a and 62b. The ferromagnetic films 62a and 62b are connected to the ferromagnetic film 61 to form a magnetic circuit, and the ferromagnetic film 61 functions as a so-called yoke because its opening is smaller than the wiring width as shown. That is, in the present embodiment, a structure in which the generated magnetic field of the upper wiring is effectively applied to the magnetoresistive film 31 can be realized. It also has a shielding function against an external magnetic field.

FIGS. 12 and 13 are sectional views showing the steps of manufacturing the magnetoresistive element of the fifth embodiment step by step. The manufacturing process of the magnetoresistive element of this embodiment is basically the same as the manufacturing process of the fourth embodiment, but one example of the manufacturing method will be briefly described. Known methods can be used except for the method of manufacturing the peripheral portion of the magnetoresistive element, which is a characteristic part of the present invention, and is not limited to the following method.

First, the first insulating layer 2 is formed so as to cover the lower electrode 11 on the base insulating layer 10 in the same manner as in FIG.
1 is deposited (FIG. 12A). Further, thereafter, a trench for embedding the ferromagnetic film 61 is opened in the first insulating layer 21, and the ferromagnetic film 61 is deposited and planarized to form FIG.
The structure shown in (b) is obtained. However, in the fifth embodiment, the ferromagnetic film 6 made of a soft magnetic material having conductivity is used.
1 is electrically connected to the upper electrode 51 via the ferromagnetic films 62a and 62b.
Must be electrically insulated. This can be solved by forming a trench for burying the ferromagnetic film 61 so as not to reach the lower electrode 11 as shown in FIG.

Thereafter, in the same manner as in the fourth embodiment, the first insulating film 21 in the region surrounded by the ferromagnetic film 61 is removed to form a concave portion 61a (FIG. 12C). Recess 6
1a, a magnetoresistive film 31 is formed (FIG. 12).
(D)). Next, the recess 61a is buried with the second insulating film 41 (FIG. 12E), and is planarized by CMP to expose the upper contact metal of the magnetoresistive film 31 (FIG. 12F).

Next, an upper electrode 51 is formed, and a ferromagnetic film 62a is formed thereon (FIG. 13A). Subsequently, a ferromagnetic film 62b is formed on the entire surface (FIG. 13B), and is etched back by RIE to leave the ferromagnetic film 62b on the side wall of the upper electrode 51 (FIG. 13C).

In the fifth embodiment, the structure in which the ferromagnetic film 62 and the upper electrode 51 are electrically connected has been described. For example, an insulator may be inserted between the ferromagnetic film 62 and the upper electrode 51. Thus, a structure in which the ferromagnetic film 62 and the upper electrode 51 are electrically insulated can be realized. In this case, the ferromagnetic film 61 and the lower electrode 11 may be electrically connected.

(Sixth Embodiment) FIG. 14 shows a sixth embodiment of the present invention.
FIG. 4 is an element cross-sectional view schematically illustrating a structure of a magnetoresistive element according to the embodiment. In the figure, 11 is a lower electrode, 21 is a first insulating layer, 31 is a magnetoresistive film, 41 is a second insulating layer, and 51 is an upper electrode. Numerals 61 and 63 are ferromagnetic films, 10 is a base insulating layer, and 71 is a buried wiring.

The sixth embodiment is basically similar to the fourth and fifth embodiments.
This embodiment is the same as the first embodiment, but is characterized in that the whole is formed on the embedded wiring 71. Embedded wiring 71
Are covered on three sides with a ferromagnetic film 63, and the ferromagnetic film 63 is connected to the ferromagnetic film 61 to form a magnetic circuit.

The ferromagnetic films 61 and 6 in the sixth embodiment
For 3, it is preferable to use a high-permeability soft magnetic alloy such as a NiFe alloy or an amorphous alloy.

The sixth embodiment is characterized in that the buried wiring 71 has a so-called magnetic shield structure whose three surfaces are covered with a ferromagnetic film 63. The ferromagnetic film 63 is connected to the ferromagnetic film 61 to form a magnetic circuit, and the ferromagnetic film 61 functions as a so-called yoke because its opening is smaller than the wiring width as shown. That is, in the present embodiment, a structure in which the generated magnetic field of the upper wiring is effectively applied to the magnetoresistive film 31 can be realized. It also has a shielding function against an external magnetic field.

FIGS. 15 and 16 are sectional views showing the steps of manufacturing the magnetoresistive element of the sixth embodiment step by step. The manufacturing process of the magnetic element of the sixth embodiment is basically similar to that of the fourth embodiment.
This is the same as the manufacturing process of the embodiment. The connection between the ferromagnetic film 61 and the ferromagnetic film 63 can be realized by forming a trench for embedding the ferromagnetic film 61 so as to reach the embedded wiring 71.

An example of a method of forming the magnetoresistive element of the sixth embodiment will be schematically described with reference to FIGS. Known methods can be used except for the method of manufacturing the peripheral portion of the magnetoresistive element, which is a characteristic part of the present invention, and is not limited to the following method.

First, a trench is formed in the base insulating layer 10 (FIG. 15A), a ferromagnetic film 63 is formed on the entire surface, and a metal layer 71 serving as an embedded wiring is deposited (FIG. 15).
(B)).

[0100] After that, etched back until the upper surface of the base insulating layer 10 is exposed (FIG. 15 (c)), for example SiO ₂
An insulating layer 12 made of
1 is formed (FIG. 15D). Further, a first insulating layer 21 is formed thereon (FIG. 15E).

Next, a trench penetrating the first insulating layer 21 and the insulating layer 11 and reaching the ferromagnetic film 63 is formed, and the ferromagnetic film 61 is buried (FIG. 16A). Next, resist 7
4, the outer peripheral portion of the trench is covered, the first insulating film 21 in the region surrounded by the trench is removed, and the lower electrode 11 is exposed (FIG. 16B).

A magnetoresistive film 31 is formed on the lower electrode 11 (FIG. 16C), buried with a second insulating film 41, and flattened until the contact metal is exposed (FIG. 1).
6 (d)). By forming the upper electrode 51 on the contact metal, the magnetoresistive film of the sixth embodiment is completed (FIG. 16E).

Note that the present invention is not limited to the above-described embodiment, and some forms can be used in combination without departing from the spirit of the present invention. For example, when the fifth and sixth embodiments are combined, a structure in which the magnetoresistive film is completely covered with the magnetic shield can be obtained, which is preferable.

[0104]

As described in detail above, by using the magnetoresistance effect element of the present invention, the use of an etching method by physical sputtering such as an ion milling method can be minimized. This not only makes it possible to reduce the effects of the re-adhesion of the material to be processed, the reduction in the dimensional conversion difference, and the effect of electrostatic breakdown, which cause deterioration in the characteristics of the wafer and a decrease in the yield. By defining the dimensions, it is possible to obtain a magnetoresistive element in which a bias film is arranged in a self-aligned manner and a method of manufacturing the same, and a magnetoresistive element in which a yoke structure is arranged in a self-aligned manner.

[Brief description of the drawings]

FIG. 1 is a sectional view of a magnetoresistive element according to a first embodiment of the present invention.

FIG. 2 is an element cross-sectional view showing step by step the manufacturing process of the magnetoresistive element of the first embodiment.

FIG. 3 is an element cross-sectional view in a step following FIG. 2;

FIG. 4 is an element cross-sectional view showing step by step the manufacturing process of the magnetoresistive element according to the second embodiment of the present invention.

FIG. 5 is an element cross-sectional view in a step following FIG. 4;

FIG. 6 is an element cross-sectional view showing a step of manufacturing a magnetoresistive element according to a third embodiment of the present invention.

FIG. 7 is an element cross-sectional view in a step following FIG. 6;

FIG. 8 is a sectional view of a magnetoresistive element according to a fourth embodiment of the present invention.

FIG. 9 is an element cross-sectional view showing step by step the manufacturing process of the magnetoresistive element of the fourth embodiment.

FIG. 10 is an element cross-sectional view in a step following FIG. 9;

FIG. 11 is a sectional view of a magnetoresistive element according to a fifth embodiment of the present invention.

FIG. 12 is an element cross-sectional view showing step by step the manufacturing process of the magnetoresistive element of the fifth embodiment.

FIG. 13 is an element cross-sectional view in a step following FIG. 12;

FIG. 14 is a sectional view of a magnetoresistive element according to a sixth embodiment of the invention.

FIG. 15 is an element sectional view showing step by step the manufacturing process of the magnetoresistive element of the sixth embodiment.

FIG. 16 is an element cross-sectional view in a step following FIG. 15;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Lower electrode 10, 21, 41 ... Insulating film 21a, 21a '... Opening 22 ... Resin layer 23 ... Hard mask layer 24 ... Photoresist 31 ... Magnetoresistive film 301 ... Lower device electrode 302 ... Junction barrier 303 ... Upper part Device electrode 304: contact metal (electrode) 51: upper electrode 61, 62, 63 ... ferromagnetic film 71: embedded wiring

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01F 10/30 H01L 43/12 H01L 27/105 G01R 33/06 R 43/12 H01L 27/10 447 (72 ) Inventor Susumu Hashimoto 1 Toshiba-cho, Komukai-shi, Kawasaki-shi, Kanagawa F-term in Toshiba R & D Center (reference) 2G017 AA01 AB07 AD55 AD65 5D034 BA03 BA08 BA15 DA07 5E049 AA01 AA04 AA07 BA12 DB12 GC01 5F083 FZ10 GA02 GA03 GA27 JA36 JA39 JA40 JA56 JA58 JA60 PR03 PR06 PR07 PR21 PR22 PR29 PR39 PR40

Claims (7)

[Claims] A first insulating layer formed on a surface of the lower electrode; an opening formed on the first insulating layer to reach a surface of the lower electrode; and an inside of the opening separated from a side wall of the opening. A magnetoresistive film connected to the formed lower electrode;
A magnetoresistive element comprising: a second insulating layer formed between a side wall of the opening and the magnetoresistive film; and an upper electrode connected to the magnetoresistive film. 2. An upper surface of the magnetoresistive film, the first insulating layer and the second insulating layer are substantially flush with each other, and the upper electrode is formed on an upper surface of the magnetoresistive film. The magnetoresistance effect element according to claim 1, wherein: 3. The method according to claim 1, wherein the first insulating layer and the second insulating layer are made of different materials.
3. The magnetoresistive effect element according to 1. 4. A ferromagnetic film formed in contact with a side wall of the opening and separated from the magnetoresistive film and having a coercive force larger than that of the magnetoresistive film, 4. The magnetoresistive element according to claim 1, comprising any one of a ferromagnetic film having a high magnetic permeability. 5. A lower electrode in which a first insulating layer and a hard mask layer are stacked in this order is prepared, an opening is formed in the hard mask layer, and the hard mask layer having the opening is used as a mask. The first insulating layer is selectively removed by anisotropic etching until the first insulating layer reaches the lower electrode; a magnetoresistive film is formed on the upper surface of the lower electrode exposed through the opening; Depositing a second insulating film in the concave portion of the substrate, filling the magnetoresistive film, removing the first and second insulating films in a plane until the upper electrode of the magnetoresistive film is exposed, A method for manufacturing a magnetoresistive element, comprising forming an upper electrode connected to a top contact electrode of an effect film. 6. A lower electrode having a first insulating layer formed on an upper surface thereof is provided, and a trench having a closed structure is formed in a plane substantially reaching the lower electrode in the first insulating layer. A first insulating layer surrounded by the ferromagnetic film is selectively removed to form an opening exposing an upper surface of the lower electrode, and the lower portion exposed through the opening is formed. A magnetoresistive film is formed on the upper surface of the electrode,
Depositing a second insulating film through the opening, removing the first and second insulating films and the ferromagnetic film in a planar manner until an upper contact electrode of the magnetoresistive effect film is exposed; Forming an upper electrode connected to the upper contact electrode of (1). 7. A first insulating layer is formed on a lower electrode, two grooves substantially reaching the lower electrode in a predetermined cross section are formed in the first insulating layer, and a ferromagnetic film is formed in the two grooves. And an opening reaching the upper surface of the lower electrode is formed by selectively removing the first insulating layer sandwiched between the two grooves, and a magnetoresistive effect is formed on the upper surface of the lower electrode in the opening. Forming a film, forming a second insulating layer between the side wall of the magnetoresistive film and the side wall of the opening, and making the upper surfaces of the magnetoresistive film and the first and second insulating layers substantially the same And forming an upper electrode connected to the magnetoresistive film after forming the surface.