JPH11328627A - Sputtering apparatus and sputtering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering apparatus and a sputtering method whereby the composition of a thin film can be adjusted to a desired value. SOLUTION: A sputtering apparatus 1 for forming a thin film on a substrate by sputtering includes a composition analysis device 8 for analyzing the composition of the thin film formed on the substrate 11, and a gas pressure control device 9 for controlling the gas pressure of a sputtering gas in accordance with the analyzed composition of the thin film by the composition analysis device 8. The composition analysis device 8 analyzes the composition of the thin film formed on the substrate in a state where the sputtering is carried out continuously, and the gas pressure control device 9 controls the pressure of the sputtering gas in accordance with the composition of the thin film analyzed by the composition analysis device 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a sputtering apparatus and a sputtering method.

[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. . The first soft magnetic film and the second soft magnetic film are separated by a non-magnetic film, and an antiferromagnetic film is provided on the second soft magnetic film, so that the second magnetic film in contact with the antiferromagnetic film is formed. The film is magnetized in a certain direction. On the other hand, the first soft magnetic film separated by the non-magnetic film does not have a fixed magnetization direction. That is, the antiferromagnetic film fixes the magnetization direction of the second soft magnetic film in contact with the antiferromagnetic film in a predetermined direction.

As a material for such an antiferromagnetic film, for example, a material represented by Mn-X is used. X includes, for example, Ir, Pt, Rh and the like. An antiferromagnetic film is formed by performing sputtering using such a material as a target.

The properties such as the corrosion resistance of the antiferromagnetic film and the fixing strength of the soft magnetic film laminated on the antiferromagnetic film are represented by Mn and X
It is known that the ratio varies depending on the composition ratio. Especially,
The purpose of forming an antiferromagnetic film in a spin valve film is as follows.
This means fixing the magnetization direction of the soft magnetic film. for that reason,
Among the characteristics of the antiferromagnetic film, the strength of immobilization of the soft magnetic film is important in use. It is known that the immobilization strength of the soft magnetic film has a certain peak depending on the composition of the antiferromagnetic film. Therefore, when forming an antiferromagnetic film, usually, a material having a composition near this peak is used.

[0006]

However, in the Mn-X-based material as described above, the range of the composition showing this peak is very narrow. In the sputtering method, Mn-X
Even if is used as a target, the composition of Mn-X of the target does not always match the composition of Mn-X of the formed thin film because the sputtering rates of Mn and X are different.

Therefore, as a method of controlling the composition of a thin film formed by sputtering, a method of changing the composition of a target has been adopted. However, in this method, in order to obtain a thin film having a desired composition, it is necessary to perform test film formation by changing the composition of the target several times, and it takes a long time to determine the composition of the target. . Further, the composition of the obtained thin film could be known only after the film formation was completed.

Further, even if the composition of the target is once determined, the composition of the target surface changes during sputtering using the target due to the difference in the sputtering rate of the material constituting the target. The period during which one target could be used was very short.

Further, Ir, R used for the antiferromagnetic film
Since noble metals such as h and Pt are very expensive, the production cost is increased by repeating the test film formation.
In order to reduce the cost, it is preferable to reduce the ratio of the above-mentioned noble metal in the target.
Heretofore, it has been difficult to obtain a thin film having a desired composition because the composition of the thin film is determined by the sputtering rate of the material and the apparatus configuration.

The present invention has been proposed in view of the above-mentioned conventional circumstances, and has as its object to provide a sputtering apparatus and a sputtering method capable of adjusting the composition of a thin film to a desired value.

[0011]

SUMMARY OF THE INVENTION A sputtering apparatus according to the present invention is a sputtering apparatus for forming a thin film on a substrate by sputtering, comprising: a composition analyzing means for analyzing a composition of a thin film formed on a substrate; Gas pressure control means for controlling the gas pressure of the sputtering gas according to the composition of the thin film analyzed by the analysis means, wherein the composition analysis means, on the substrate while sputtering is continuously performed The composition of the formed thin film is analyzed, and the gas pressure control means controls the gas pressure of the sputtering gas according to the composition of the thin film analyzed by the composition analysis means.

In the sputtering apparatus according to the present invention as described above, since the composition of the thin film formed on the substrate is analyzed by the composition analysis means, the composition of the thin film is confirmed while forming the film. You. Further, in this sputtering apparatus, since the gas pressure is controlled by the gas pressure control means according to the composition of the thin film, a thin film having a predetermined composition is formed.

[0013] Further, the sputtering method of the present invention comprises a film forming step of forming a thin film on a substrate by sputtering, a composition analyzing step of analyzing a composition of the thin film formed on the substrate in the film forming step, A gas pressure control step of controlling a gas pressure of a sputtering gas according to the composition of the thin film analyzed in the composition analysis step is provided.The composition analysis step and the gas pressure control processing step are performed, and the film formation step is continued. It is characterized in that it is performed in a state where it is performed.

In the sputtering method according to the present invention as described above, the composition of the thin film formed on the substrate in the film forming step is analyzed in the composition analysis step. The composition of the thin film is confirmed. Also,
In this sputtering method, in the gas pressure control step,
Since the gas pressure of the sputtering gas is controlled according to the composition of the thin film analyzed in the composition analysis step, a thin film having a predetermined composition is formed. Furthermore, in this sputtering method,
Since the composition analysis step and the gas pressure control processing step are performed in a state where the film formation step is continuously performed, the composition of a thin film to be formed is kept constant at a predetermined composition.

[0015]

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
The apparatus includes a vacuum exhaust device 6, a sputtering gas introducing device 7, a composition analyzing device 8, and a control processing device 9.

The target 10 is supported on the backing plate 3. A substrate 11 is provided on the holder 5.

The target 10 is made of a metal material, an inorganic material, or the like selected according to a target thin film.
It is formed in a flat plate shape corresponding to the size of the substrate 11.

The backing plate 3 includes a target 10
It has a flat plate shape with a larger area than that, and is made of a metal material such as Cu having excellent thermal conductivity. The backing plate 3 supports the target 10 and
It is connected to a power supply (not shown) and forms 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 10 supported by the backing plate 3.

The magnet section 4 is disposed on the backing plate 3 on the side opposite to the side on which the target 10 is supported.
The magnet 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 10. 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 provided to face the target 10 and supports a substrate 11 on which a thin film is to be 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 to suppress a rise in the temperature of the substrate 11 during sputtering.

An exhaust port 12 and a sputter gas inlet 13 are provided on the side wall of the sputtering apparatus 1. The evacuation port 12 is connected to the vacuum evacuation device 6, and the sputter gas introduction port 13 is connected to the sputter gas introduction device 7. Then, the sputtering gas introduction device 7 introduces the sputtering gas into the vacuum chamber 2 from the sputtering gas introduction port 13, and the vacuum exhaust device 6 exhausts the gas in the vacuum chamber 2 from the exhaust port 12. Is maintained in a predetermined high vacuum state. Note that, for example, Ar or the like is used as the sputtering gas.

The composition analyzer 8 analyzes the composition of the thin film formed on the substrate 11. By incorporating the composition analyzer 8 in the apparatus like the sputtering apparatus 1, it is possible to know the composition of the thin film while performing sputter deposition.

As the composition analyzer 8, for example, an X-ray photoelectron spectrometer or the like is used. X-ray photoelectron spectroscopy (XP
S: X-ray photoelectron spectroscopy) is a method of irradiating a sample with X-rays of known energy, measuring the kinetic energy of the electrons ionized thereby, and knowing the binding energy of the electrons. A feature of XPS is that not only can the type of element be known from its binding energy, but also information about the chemical state of the element in the sample can be obtained.

FIG. 2 is a diagram conceptually showing the configuration of the X-ray photoelectron spectroscopy apparatus. The X-ray photoelectron spectroscopy device 20 is roughly divided into an X-ray emission unit 22 that irradiates the sample 21 with X-rays, and a measurement unit 23 that measures the energy of electrons in the sample ionized by the X-rays. .

The X-ray emitting section 22 has an X-ray tube 24.
As the X-ray, for example, Mg Kα ray (1254 eV)
Alternatively, Al Kα ray (1487 eV) or the like is used. The measuring unit 23 includes an electron energy analyzer 25 and a detector 26. As the electron energy analyzer 25, for example, an electric field deflection type concentric spherical electrode type energy analyzer or the like is used. As the detector 26, for example,
An electron multiplier or the like is used.

When an X-ray photoelectron spectrometer is used as the composition analyzer 8, as shown in FIG. 3, the sputtering device 1 includes an X-ray emission part 22 for irradiating a thin film on the substrate 11 with X-rays, A measuring unit 23 for measuring the energy of electrons from the sample is provided.

The desired thin film composition is previously input and set in the control processor 9. The control processing device 9 compares the composition of the thin film detected by the composition analysis device 8 with a preset composition, and calculates a condition for setting the composition of the thin film to a desired value. Control for optimizing. As a condition control for setting the composition of the thin film to a desired value, for example, control of a sputtering gas pressure can be mentioned.

Then, such a sputtering apparatus 1
Then, the distance t between the target 10 and the substrate 11 is longer than 5 cm to 10 cm, which is the distance between the target and the substrate in a conventional sputtering apparatus, and specifically, is set to about 20 cm or more. Is preferred.

By increasing the distance between the target 10 and the substrate 11, the discharge space becomes longer, and the influence of the magnetron magnetic field of the cathode and the influence of non-uniform plasma generated near the cathode are reduced. Therefore, the strength of the magnet part 4 can be reduced as compared with the conventional case. In addition, when the distance between the target 10 and the substrate 11 is increased, the sputtering gas pressure can be made lower than before in order to prevent scattering of sputter particles. Conventionally, the sputtering gas pressure could only be reduced to about 1 mTorr, but by increasing the distance between the target 10 and the substrate 11, the gas pressure can be reduced to less than 1 mTorr, and the range of usable gas pressure is limited. Become wider. Specifically, in this sputtering apparatus, 0.3 mTorr to 20 mTorr
Film formation can be performed at a gas pressure in the range of r.

Further, by increasing the distance between the target 10 and the substrate 11, sputtered particles spattered from the target 10 and spattered from the target 10 are generated.
Since the light is perpendicularly incident on the substrate 11, the substrate 1
1, the incident angle of the sputtered particles becomes substantially constant. Further, when the distance between the target 10 and the substrate 11 is increased, the sputtered particles uniformly enter the entire surface of the substrate 11, 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 with a vacuum exhaust device 6, then the evacuation speed is reduced and the sputtering gas inlet 13 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 sputter gas inlet 13.
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 inlet 13 is turned into plasma by the glow discharge, and ionized Ar ions, which are ionized, collide with the target 10.
Atoms are ejected. At this time, the magnet part 4 is provided on the back side of the backing plate 3, and a magnetic field is formed near the target 10, so that the ionized ions are concentrated near the target 10.

The atoms repelled from the target 10 adhere and deposit on a substrate 11 provided to face the target 10 to form a thin film.

Then, in parallel with the formation of the thin film, the composition analyzer 8 analyzes the composition of the thin film formed on the substrate 11. When an X-ray photoelectron spectrometer is used as the composition analyzer 8, first, as shown in FIG.
Irradiates the thin film on the substrate 11 with X-rays 27. The electrons 28 in the thin film ionized by the X-rays 27
The kinetic energy of the thin film is measured and analyzed by the measuring unit 23, whereby the composition of the thin film can be known.

Then, information on the composition of the thin film detected by the composition analyzer 8 is input to the control processor 9. The desired thin film composition is previously input and set in the control processing device 9. Then, the control processing device 9 compares the detected composition of the thin film with the set composition of the thin film, and calculates a sputtering gas pressure for setting the composition of the thin film to a desired composition. Then, the control processing device 9 sets the evacuation device 6 in order to set the sputtering gas pressure to the calculated value.
Alternatively, the operation of the sputtering gas introduction device 7 is controlled.

The vacuum exhaust device 6 or the sputter gas introducing device 7 operates according to the control command from the control processing device 9 to adjust the sputter gas pressure to a desired value. Specifically, for example, when the sputtering gas pressure is to be increased, while the exhaust speed from the vacuum exhaust device 6 is kept constant,
By increasing the amount of sputter gas introduced from the sputter gas introduction device 7, the sputter gas pressure can be adjusted to a desired value. When the sputtering gas pressure is to be reduced, the sputtering gas pressure is reduced by reducing the amount of the sputtering gas introduced from the sputtering gas introduction device 7 while keeping the exhaust speed from the vacuum exhaust device 6 constant. It can be adjusted to a desired value.

The sputtering gas pressure may be adjusted to a desired value by changing the exhaust speed from the vacuum exhaust device 6 while keeping the sputtering gas introduction amount from the sputtering gas introduction device constant.

The above-described series of operations of thin film composition analysis, control processing, and sputtering gas pressure adjustment are sequentially performed in parallel with the formation of the thin film, so that the composition of the thin film becomes a desired value and the thin film is formed. The composition can be kept constant.

In the sputtering apparatus 1, the composition of the formed thin film is analyzed while forming the film.
Film formation can be performed while checking the composition of the thin film. Furthermore, in the sputtering apparatus 1, the range of the usable sputtering gas pressure is widened by increasing the distance between the target and the substrate. In this sputtering apparatus, as shown in an experiment described later, the composition of the thin film changes almost linearly according to the change in the sputter gas pressure. Can be a value.

An experiment for examining the relationship between the sputtering gas pressure and the composition of the thin film will be described below.

The inventor formed a thin film using a sputtering apparatus in which the distance between the target and the substrate was 40 cm. At this time, the relationship between the sputtering gas pressure and the composition of the thin film was examined by changing the sputtering gas pressure during sputtering. In this experiment, no control was performed to make the formed thin film a predetermined composition.

First, a thin film was formed using Mn-Ir (composition ratio Mn: Ir = 82: 18) as a target.
FIG. 4 shows the relationship between the sputtering gas pressure (mTorr) and the Ir concentration (atomic%) of the thin film at this time. As is clear from FIG. 4, the lower the sputtering gas pressure, the lower the Ir concentration in the thin film. It can be seen that the concentration of Ir in the thin film changes almost linearly with the change in the sputtering gas pressure. In addition, Mn-R as a target
h (composition ratio Mn: Rh = 80: 20), a thin film was similarly formed. At this time, the sputtering gas pressure (mTorr)
FIG. 5 shows the relationship between r) and the Rh concentration (atomic%) of the thin film. As is clear from FIG. 5, the Rh concentration of the thin film decreases as the sputtering gas pressure decreases. It can be seen that the Rh concentration of the thin film changes almost linearly with the change of the sputtering gas pressure.

As described above, it was found that by increasing the distance between the target and the substrate, the composition of the thin film obtained by sputtering changes almost linearly with the change in the sputtering gas pressure. Therefore, it was found that the composition of the thin film could be set to a desired value by changing the sputtering gas pressure.

Therefore, in this sputtering apparatus 1,
By analyzing the composition of the formed thin film while forming the film, and controlling the sputtering gas pressure according to the result,
The composition of the thin film can be kept at a desired value.

When a spin valve film is formed by the sputtering apparatus 1, the composition of the antiferromagnetic film can be adjusted to a desired value. Can be a composition having a peak in the intensity of the magnetization fixed. Further, when a spin valve film is formed by this sputtering apparatus, the ratio of the noble metal in the target can be reduced, and the cost of the spin valve film can be reduced.

The sputtering apparatus and the sputtering method of the present invention are particularly suitable when applied to the formation of a spin valve film in which the composition of the antiferromagnetic film largely depends on its characteristics. However, the sputtering apparatus and the sputtering method of the present invention are not limited to this,
It is widely applicable when a thin film made of a plurality of materials is formed by sputtering.

[0049]

According to the present invention, since the composition of the formed thin film is analyzed while performing the sputtering film formation, the film can be formed while confirming the composition of the thin film. Further, in the present invention, the composition of the thin film can be adjusted to a desired value by controlling the gas pressure according to the result of the composition analysis of the thin film.

Further, according to the present invention, since the composition of the thin film can be controlled by controlling the gas pressure, it is possible to reduce the number of test depositions when forming the thin film and to increase the length of one target. Can be used for a period,
Costs can be reduced.

Therefore, according to the present invention, a thin film having a desired composition can be formed at a low cost with a uniform composition.

[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 illustrating a configuration example of an X-ray photoelectron spectroscopy device.

FIG. 3 is a diagram schematically showing another configuration example of the sputtering apparatus of the present invention.

FIG. 4 shows a case where Mn-Ir is used as a target.
FIG. 4 is a diagram showing a relationship between a sputtering gas pressure and a composition of a thin film.

FIG. 5 shows a case where Mn-Rh is used as a target.
FIG. 4 is a diagram showing a relationship between a sputtering gas pressure and a composition of a thin film.

[Explanation of symbols]

1 sputtering equipment, 2 vacuum chamber, 3
Target, 4 backing plate, 5 magnet part, 6 substrate, 7 holder, 8 evacuation device,
9 sputtering gas introduction device, 10 composition analyzer,
11 Control processor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/203 H01L 21/203 S 43/12 43/12 (72) Inventor Satoshi Ikeda 2500 Hagizono, Higazono, Chigasaki City, Kanagawa Prefecture Japan Vacuum Engineering Inside the corporation

Claims (6)

[Claims] 1. A sputtering apparatus for forming a thin film on a substrate by sputtering, comprising: a composition analyzing means for analyzing the composition of the thin film formed on the substrate; and a method according to the composition of the thin film analyzed by the composition analyzing means. Gas pressure control means for controlling the gas pressure of the sputtering gas, wherein the composition analysis means analyzes the composition of the thin film formed on the substrate while sputtering is continuously performed, A sputtering apparatus, wherein the control means controls the gas pressure of the sputtering gas according to the composition of the thin film analyzed by the composition analysis means. 2. The sputtering apparatus according to claim 1, wherein a distance between a target, which is a material of the thin film, and the substrate is 20 cm or more. 3. The sputtering apparatus according to claim 1, wherein said composition analyzing means is an X-ray photoelectron analyzer. 4. A film forming step of forming a thin film on a substrate by sputtering; a composition analyzing step of analyzing a composition of the thin film formed on the substrate in the film forming step; A gas pressure control step of controlling the gas pressure of the sputtering gas according to the composition of the thin film, wherein the composition analysis step and the gas pressure control processing step are performed in a state where the film formation step is continuously performed. Performing a sputtering method. 5. A target, which is a material of a thin film formed on the substrate, is disposed so as to face the substrate,
5. The sputtering method according to claim 4, wherein a distance between the substrate and the target is set to 20 cm or more. 6. The sputtering method according to claim 4, wherein in the composition analysis step, the composition of the thin film formed on the substrate is analyzed by X-ray photoelectron analysis.