JPH11328628A - Sputtering apparatus, sputtering method and method for forming spin valve film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering apparatus, a sputtering method and a method for forming a spin valve film whereby a thin film can be formed on a wafer of a large diameter with less variation in film thickness distribution even by the use of a small target. SOLUTION: A sputtering apparatus 1 has a chamber 2 in which a substrate 9 and a target 8 are opposed to each other, and a sputtering gas introduction pipe 11 of a plurality of gas jet-out openings 12. A sputtering gas is introduced into the chamber from the jet-out openings 12 formed in the sputtering gas introduction pipe 11, thereby sputtering the target 8 and form a thin film on the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sputtering apparatus, a sputtering method, and a method for forming a spin valve film.

[0002]

2. Description of the Related Art A magnetoresistive head is a read-only magnetic head using a magnetoresistive element as a magnetosensitive element, and has been put to practical use in hard disk drives and the like. In recent years, a giant magnetoresistance effect element using a spin valve film has been adopted as a magnetoresistance effect element used in such a magnetoresistance effect type magnetic head.

The spin valve film basically has a four-layer structure in which a first soft magnetic film, a non-magnetic film, a second soft magnetic film, and an antiferromagnetic film are laminated in this order. . Such a spin valve film is usually formed by sputtering.

[0004]

When a magnetic head using a spin-valve film is manufactured, a number of spin-valve-type magnetic head elements are formed on a wafer by repeating film formation, patterning, and etching. By dividing the valve type magnetic head element for each element, a spin valve type magnetic head can be obtained. Therefore, when a large number of magnetic heads are manufactured, it is necessary to increase the size of the wafer.

[0005] Further, since the spin valve film is formed by laminating a thin film on the order of nanometers, if the film thickness distribution varies within the wafer, the characteristics of the spin valve film vary within the wafer. Therefore, when a large-sized wafer is used, it is necessary to increase the size of the target in order to suppress variations in the film thickness distribution within the wafer.

[0006] Therefore, when manufacturing is to be performed using a large-sized wafer, a large-sized film forming apparatus capable of disposing a large target is required. A large film forming apparatus is expensive and consumes more power. In addition, when the size of the target is increased, more material is required, and the production cost increases.

The present invention has been proposed in view of the above-mentioned conventional circumstances. Even when a small target is used, a thin film can be formed on a large-diameter wafer with less variation in film thickness distribution. It is an object of the present invention to provide a sputtering apparatus, a sputtering method, and a method for forming a spin-valve film that can be performed.

[0008]

According to the present invention, a sputtering apparatus includes a chamber in which a substrate and a target are arranged to face each other, and a sputtering gas inlet pipe having a plurality of sputter gas outlets formed therein. A sputter gas is introduced into the chamber from a plurality of outlets formed in the gas introduction pipe, and a target is sputtered by the sputter gas to form a thin film on the substrate.

In the sputtering apparatus according to the present invention as described above, since the sputter gas is introduced into the chamber from a plurality of outlets, the concentration of the sputter gas does not fluctuate, and the conditions for forming a thin film are good. Becomes
The properties of the obtained thin film are improved.

According to the sputtering method of the present invention, a substrate and a target are opposed to each other inside a chamber, and a sputter gas is introduced into the chamber through a sputter gas introduction pipe having a plurality of sputter gas outlets. The method is characterized in that the target is sputtered by a sputtering gas introduced into the chamber to form a thin film on the substrate.

In the sputtering method according to the present invention as described above, the sputter gas is introduced into the chamber from the sputter gas introduction pipe having a plurality of spout outlets for the sputter gas. Variations are eliminated, the conditions for forming the thin film are improved, and the characteristics of the obtained thin film are improved.

Further, the method of forming a spin valve film according to the present invention is characterized in that a spin valve film formed by laminating at least a first soft magnetic film, a non-magnetic film, a second soft magnetic film and an antiferromagnetic film is formed. In forming the film, the nonmagnetic film is formed by sputtering Cu, and a sputter gas pressure at the time of forming the nonmagnetic film is set to 2 mTorr or more.

In the spin valve film forming method according to the present invention as described above, the sputtering gas pressure when forming the nonmagnetic film of the spin valve film by sputtering Cu is set to 2 mTorr or more. The stability of the magnetic film is improved, the diffusion of Cu at the interface between the non-magnetic film and the laminated magnetic film is suppressed, and the resistance change rate of the obtained spin valve film is increased.

[0014]

Embodiments of the present invention will be described below.

FIG. 1 is a diagram conceptually showing an example of the configuration of a sputtering apparatus according to the present invention. The sputtering apparatus 1 includes a backing plate 3, a magnet unit 4, and a holder 5 in a vacuum chamber 2 in which the inside is in a high vacuum state. Further, this sputtering apparatus 1
A vacuum exhaust device 6 and a sputtering gas introducing device 7 are provided.

A target 8 is supported on the backing plate 3. A substrate 9 is disposed on the holder 5.

The target 8 is made of a metal material, an inorganic material, or the like selected according to a target thin film, and is formed in a flat plate shape corresponding to the size of the substrate 9.

The backing plate 3 has a flat plate shape having a larger area than the target 8 and is made of a metal material such as Cu having excellent heat conductivity. The backing plate 3 supports the target 8 and is connected to a power source (not shown) to form a cathode electrode.
Further, a cooling mechanism (not shown) is attached to the backing plate 3 so as to suppress a temperature rise of the target 8 supported by the backing plate 3.

The magnet section 4 is provided on the backing plate 3 on the side opposite to the side on which the target 8 is supported. The magnet section 4 forms a magnetic field in a direction orthogonal to an electric field generated between the cathode electrode and the anode electrode, that is, a direction substantially parallel to the surface of the target 8. This magnet part 4 is, for example, a columnar first magnet 4a arranged in the center.
And an annular second magnet 4b arranged outside the first magnet 4a at a predetermined distance.

The holder 5 is arranged to face the target 8 and supports a substrate 9 on which a thin film is formed.
The holder 5 is connected to a power source (not shown) and forms an anode electrode. Further, a cooling mechanism (not shown) is attached to the holder 5 so as to suppress an increase in the temperature of the substrate 9 during sputtering.

An exhaust port 10 and a sputter gas introduction pipe 11 are provided on the side wall of the sputtering apparatus 1. A vacuum exhaust device 6 is connected to the exhaust port 10 to exhaust gas in the vacuum chamber 2.

The sputter gas introduction pipe 11 is formed in an annular shape having a diameter larger than that of the target 8 as schematically shown in FIG. The sputter gas inlet pipe 11 has a plurality of sputter gas outlets 12.
Are formed at substantially equal intervals on the inner peripheral side of the annular sputter gas introduction pipe 11. The number of sputter gas outlets 12 is not particularly limited, but is, for example, five.
Further, a sputter gas introducing device 7 is connected to the sputter gas introducing tube 11, and the sputter gas sent out from the sputter gas introducing device 7 is supplied to the sputter gas introducing tube 11.
Are introduced into the vacuum chamber 2 from a plurality of sputter gas outlets 12 provided in the vacuum chamber 2.

Then, such a sputter gas introduction pipe 1
1 is disposed between the target 8 and the substrate 9 as shown in FIG. 1, and the distance between the sputtering gas introduction pipe 11 and the target 8 is larger than the distance between the sputtering gas introduction pipe 11 and the substrate 9. It is arranged to be small.

In this sputtering apparatus 1,
The sputtering gas introduction device 7 introduces a sputtering gas from the sputtering gas introduction pipe 11 into the vacuum chamber 2, and
When the gas in the vacuum chamber 2 is exhausted from the exhaust port 10 by the vacuum exhaust device 6, the inside of the vacuum chamber 2 is maintained in a predetermined high vacuum state. Note that, for example, Ar or the like is used as the sputtering gas.

Then, such a sputtering apparatus 1
Then, the distance t between the target 8 and the substrate 9 is longer than 5 cm to 10 cm, which is the distance between the target and the substrate in the conventional sputtering apparatus, specifically, about 20 cm or more. Is preferred.

By increasing the distance between the target 8 and the substrate 9, the discharge space becomes longer, and the influence of the magnetron magnetic field of the cathode and the influence of the non-uniform plasma generated near the cathode are reduced. In addition, by increasing the distance between the target 8 and the substrate 9, sputtered particles sputtered from the target 8 and spattered from the target 8 become
Since the light is vertically incident on the substrate 9, the incident angle of the sputtered particles is substantially constant over the entire surface of the substrate 9. Further, when the distance between the target 8 and the substrate 9 is increased, sputtered particles are uniformly incident on the entire surface of the substrate 9, so that the variation in the film thickness is very small.

Then, such a sputtering apparatus 1
When a thin film is formed, first, the inside of the vacuum chamber 2 is evacuated to a predetermined pressure by evacuating the inside of the vacuum chamber 2 to a predetermined pressure. For example, an Ar gas is introduced as a sputtering gas from above, and the inside of the vacuum chamber 2 is set to an Ar atmosphere having a predetermined gas pressure.

Then, Ar gas is introduced from the sputtering gas introduction pipe 11.
While introducing gas, a voltage is applied using the holder 5 as an anode and the backing plate 3 as a cathode. Then, a glow discharge is generated between the holder 5 constituting the anode and the backing plate 3 constituting the cathode.

The Ar gas introduced from the sputter gas introduction pipe 11 is turned into plasma by the glow discharge, and ionized ions become ionized ions. Is popped out. At this time, backing plate 3
The magnet section 4 is arranged on the back side of the target 8, and a magnetic field is formed near the target 8, so that the ionized ions are concentrated near the target 8.

The atoms ejected from the target 8 are applied to a substrate 9 provided facing the target 8.
A thin film is formed by depositing and depositing on the top.

At this time, the characteristics of the thin film formed on the substrate 9 can be improved by introducing the sputter gas from the plurality of sputter gas outlets 12. Specifically, when the thin film formed on the substrate is a spin valve film, the spin valve has a large resistance change rate.
Here, the resistance change rate refers to a value obtained by reducing the difference between the maximum resistance value and the minimum resistance value of the spin valve film by the minimum resistance value.

The characteristics of a thin film formed by sputtering are generally affected by film forming conditions. The film forming conditions include a sputter gas pressure, a scattering state of sputter particles, an incident angle of the sputter particles to the substrate, and the like. It is considered that by blowing the sputtering gas from the plurality of outlets, the concentration of the sputtering gas does not fluctuate, and this has a favorable effect on the film formation conditions as described above.

Further, it is preferable to arrange the sputter gas introduction pipe 11 such that the distance between the sputter gas introduction pipe 11 and the target 8 is smaller than the distance between the sputter gas introduction pipe 14 and the substrate 9. By blowing the sputtering gas from a position closer to the target 8, the target 8
The sputtering gas pressure in the vicinity is increased, and the conditions for forming a thin film can be made more suitable.

When the non-magnetic film of the spin valve film is made of Cu, the sputtering gas pressure at the time of sputtering is preferably 2 mTorr or more. By setting the sputter gas pressure at the time of forming the nonmagnetic film made of Cu to 2 mTorr or more, a spin valve film having a large resistance change rate can be obtained.

When the non-magnetic film of the spin valve film is made of Cu, Cu is scattered at the interface between the non-magnetic film and the soft magnetic film laminated on the non-magnetic film, and the material constituting the ferromagnetic film is mixed with Cu. There was a problem that and mixed. When the nonmagnetic film and the ferromagnetic film intersect, the multilayer structure of the spin valve film is broken, and the characteristics of the spin valve film are deteriorated. It is considered that the stability of the formed Cu film is improved by setting the sputtering gas pressure at the time of forming the nonmagnetic film made of Cu to 2 mTorr or more.

Hereinafter, an experimental example in which a spin valve film is formed by a sputtering apparatus having a configuration as shown in FIG. 1 and a distance between a target and a substrate set to 40 cm and characteristics of the spin valve film are evaluated. explain.

<Experimental Example 1> In Experimental Example 1, a spin valve film was formed by changing the position where the sputter gas was introduced, and the resistance change rate thereof was examined.

First, a base film of Ta having a thickness of 5 nm was formed on a substrate. Next, on this base film, a NiFe film of 7.5 nm, a Cu film of 2.5 nm, a NiFe film of 4.1 nm, and an IrMn film of 10 nm were laminated in this order. Further, a Ta film having a thickness of 10 nm was formed on the IrMn film to obtain a spin valve film.

The sputtering gas pressure at the time of sputtering is set to be 1.25 sputter gas pressure when forming IrMn.
mTorr, and the sputtering gas pressure for forming other films was 3 mTorr.

The spin valve film formed so that the distance between the sputtering gas introduction position and the target is smaller than the distance between the sputtering gas introduction position and the substrate is used as the first spin valve film. The spin valve film formed so that the distance between the gas introduction position and the target was larger than the distance between the sputtering gas introduction position and the substrate was used as a second spin valve film. Then, the resistance change rates of the first spin valve film and the second spin valve film were examined. As a result, in the first spin valve film, about 4%
A large resistance change rate was obtained. In contrast, the second
The rate of change in resistance of the spin valve film was about 3.3%, which was smaller than that of the first spin valve film.

Therefore, when the spin valve film is formed by sputtering, the distance between the sputtering gas introduction position and the target is made smaller than the distance between the sputtering gas introduction position and the substrate, thereby increasing the rate of change in resistance. It was found that an excellent spin valve film was obtained.

<Experimental Example 2> In Experimental Example 2, the resistance change rate of a spin valve film formed by changing the sputtering gas pressure during film formation was examined.

First, a base film of Ta having a thickness of 5 nm was formed on a substrate. Next, on this base film, a NiFe film of 3.8 nm, a CoFe film of 2.0 nm, a Cu film of 2.5 nm, a CoFe film of 2.2 nm, and an IrMn film of 10 nm are laminated in this order. did. Further, a Ta film having a thickness of 10 nm was formed on the IrMn film to obtain a spin valve film.

At this time, the Cu film was formed by changing the sputtering gas pressure when forming the film, and the resistance change rate of the obtained spin valve film was examined. Note that the sputtering gas pressure for forming a film other than the Cu film was 3 mTorr.

FIG. 3 is a diagram showing a sputtering gas pressure when a Cu film is formed and a resistance change rate of the spin valve film. As shown in FIG. 3, when the sputtering gas pressure at the time of forming the Cu film is 2 mTorr or less, the resistance change rate of the spin valve film increases as the sputtering gas pressure increases. The sputtering gas pressure for forming the Cu film is 2 mTorr.
From the above, it can be seen that the resistance change rate is constant and stable. The resistance change rate at this time is as high as about 8%.

Therefore, when forming a spin valve film by sputtering, by setting the sputtering gas pressure at the time of forming the Cu film as a non-magnetic film to 2 mTorr or more, an excellent spin valve film having a large resistance change rate can be obtained. Was obtained. When a layer other than the non-magnetic film made of Cu was formed, no change in the rate of change in resistance was observed even when the sputtering gas pressure was changed.

<Experimental Example 3> In Experimental Example 3, the in-plane distribution of the rate of change in resistance of the spin valve film formed on the substrate was examined.

First, a base film of Ta having a thickness of 5 nm was formed on a 4-inch substrate. Next, a 7.5 nm thick NiFe film and a 2.5 nm thick Cu film
And a NiFe film of 4.1 nm and an IrMn film of 10 nm
And were laminated in this order. Further, a thickness of 1 mm is formed on the IrMn film.
A spin valve film was obtained by forming a 0 nm Ta film. At this time, the size of the target was 6 inches.

The resistance change rate of the spin valve film formed on the wafer was measured at nine measurement points including the center of the surface. Table 1 shows the results. In Table 1, No. 1 to No. Reference numeral 9 denotes a measurement point at which the resistance change rate was measured on the substrate.

[0050]

[Table 1]

From Table 1, the distribution of the resistance change rate in the substrate is 1
%, Which is very small. Therefore, it was found that when a spin valve film was formed using the above-described sputtering apparatus, a spin valve film having uniform characteristics could be formed over the entire surface of the substrate.

From the above experimental examples, when forming a spin valve film by this sputtering apparatus, the distance between the sputtering gas introduction position and the target is made smaller than the distance between the sputtering gas introduction position and the substrate. As a result, it was found that a high-performance spin valve film having a large resistance change rate was obtained. Further, it was found that by using this sputtering apparatus, a spin-valve film can be formed with a uniform thickness and characteristics over the entire surface of a large-sized wafer.

Further, the non-magnetic film of the spin valve film is made of Cu.
It was found that a spin valve film having a high rate of change in resistance can be obtained by forming the Cu film at a sputtering gas pressure of 2 mTorr or more when forming the Cu film.

Therefore, according to the present invention, when forming a spin valve film by sputtering using a large-sized wafer, the size of the target is not changed without changing the size of the target.
A spin valve film can be formed with uniform characteristics over the entire surface of the wafer. In addition, even if the size of the wafer is increased, the size of the target remains the same, so that the material cost is reduced and the apparatus is not increased in size.
The production cost of the spin valve film can be reduced.

[0055]

According to the sputtering apparatus of the present invention, the sputter gas is introduced into the chamber from a plurality of outlets, whereby the conditions for forming the thin film can be improved, and the characteristics of the obtained thin film can be improved. Can be improved.

Also, in the sputtering method of the present invention,
Since the sputter gas is introduced into the above chamber from the sputter gas inlet pipe having a plurality of sputter gas outlets formed, the film forming conditions of the thin film can be improved, and the thin film having excellent characteristics can be obtained. Can be realized.

In the method of forming a spin valve film according to the present invention, the rate of change in resistance of the spin valve film is determined by defining the sputtering gas pressure when forming a Cu film which is a non-magnetic film of the spin valve film. Can be improved.

Therefore, according to the present invention, an excellent spin valve film having a large resistance change rate can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration example of a sputtering apparatus of the present invention.

FIG. 2 is a diagram schematically showing a configuration example of a sputter gas introduction pipe of FIG.

FIG. 3 is a diagram showing a relationship between a sputtering gas pressure and a resistance change rate when a spin valve film is formed.

[Explanation of symbols]

1 sputtering equipment, 2 vacuum chamber, 3
Backing plate, 4 magnets, 5 holder, 6
Vacuum exhaust device, 7 Sputter gas introduction device, 8
Target, 9 substrate, 10 exhaust port, 11 sputter gas inlet tube, 12 sputter gas outlet

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoshi Ikeda 2500 Hagizono, Chigasaki-shi, Kanagawa Japan Vacuum Engineering Co., Ltd.

Claims (13)

[Claims] 1. A spout gas inlet pipe having a plurality of sputter gas outlets formed therein, wherein a plurality of spout outlets are formed in the sputter gas inlet pipe. A sputtering gas introduced into the chamber from above, and a target is sputtered by the sputtering gas to form a thin film on the substrate. 2. The sputter gas introduction pipe is formed in a substantially annular shape, and a plurality of outlets formed in the sputter gas introduction pipe are arranged so that a sputter gas blows out between a target and a substrate. 2. The method according to claim 1, wherein
The sputtering apparatus as described in the above. 3. The sputtering apparatus according to claim 1, wherein a distance between the sputtering gas introduction pipe and the target is shorter than a distance between the sputtering gas introduction pipe and the substrate. 4. The distance between the target and the substrate is 2
2. The sputtering apparatus according to claim 1, wherein the distance is 0 cm or more. 5. A sputter gas is introduced into the chamber from a sputter gas introduction pipe having a plurality of sputter gas outlets, wherein a substrate and a target are arranged inside the chamber to face each other. And sputtering the target with the sputtering gas to form a thin film on the substrate. 6. A sputter gas inlet tube formed in a substantially annular shape as said sputter gas inlet tube, and a plurality of blowouts formed in said sputter gas inlet tube when introducing a sputter gas into said chamber. From the mouth,
The sputtering method according to claim 5, wherein a sputtering gas is blown out between the target and the substrate. 7. The sputtering gas introduction pipe according to claim 1, wherein a distance between the sputtering gas introduction pipe and the target is shorter than a distance between the sputtering gas introduction pipe and the substrate. Item 6. The sputtering method according to Item 5. 8. The distance between the target and the substrate is 2
The sputtering method according to claim 5, wherein the thickness is 0 cm or more. 9. The thin film formed on the substrate is a spin valve film formed by laminating at least a first soft magnetic film, a non-magnetic film, a second soft magnetic film, and an antiferromagnetic film. The sputtering method according to claim 5, wherein: 10. The method according to claim 1, wherein when forming the non-magnetic film, the film is formed using Cu as a material, and a sputter gas pressure when forming the non-magnetic film is set to 2 mTorr or more. 9. The sputtering method according to 9. 11. When forming a spin valve film formed by laminating at least a first soft magnetic film, a nonmagnetic film, a second soft magnetic film, and an antiferromagnetic film, the nonmagnetic film is made of Cu. A method for forming a spin valve film, comprising: forming a film by sputtering; and setting a sputtering gas pressure at the time of forming the nonmagnetic film to 2 mTorr or more. 12. When the non-magnetic film is formed, a substrate and a Cu target are opposed to each other inside the chamber, and a plurality of sputter gas outlets are formed in the chamber through a sputter gas introduction pipe. The spin valve film according to claim 11, wherein a sputtering gas is introduced, and the Cu target is sputtered by the sputtering gas introduced into the chamber to form the non-magnetic film on the substrate. Film formation method. 13. The method of claim 11, wherein a distance between the Cu target and the substrate is 20 cm or more.