JPS63105961A - Production of thin magnetic alloy film - Google Patents

Abstract

PURPOSE:To stably form a thin magnetic film having a uniform magnetostriction constant by using a specific composite target so that the compsn. of the thin magnetic film on a substrate can be controlled with high accuracy at the time of forming the thin magnetic film on the substrate by an RF magnetron sputtering method. CONSTITUTION:The target 1 provided with a magnet 7 for generating a magnetic field for focusing plasma on a rear surface and the substrate 4 for vapor deposition are disposed in a vacuum vessel 5 and after the inside of the vacuum vessel 5 is substd. with a dilute gaseous Ar atmosphere, gaseous Ar plasma is generated by impression of a high-frequency voltage, by which sputtering is generated on the surface of the target 1 and a target material is deposited on the substrate 4. The shortest distance of the inside measure of a main erosion area of the target 1 is set at the size larger than the diameter of the substrate 4 and a member 3 for controlling the compsn. is embedded in the central part thereof. The compsn. of the member 3 is made of the compsn. with which the magnetostriction is opposite from the magnetostriction with the compsn. of the target. The thin magnetic film made of the uniform compsn. having the target magnetostriction constant is thereby formed on the substrate 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a magnetic thin film alloy, and in particular, a method for controlling the alloy composition of a high-performance alloy magnetic thin film used in an electromagnetic transducer with high precision. Accordingly, the present invention relates to a method for stably forming a magnetic thin film having a target magnetostriction constant and having a uniform magnetostriction constant on a relatively large-area substrate.

[Conventional technology]

In the conventional method of forming a three-alloy film by sputtering, in order to control the composition of the formed film, there are two methods: (1) using an alloy target close to the target alloy thin film, (2) using a single target with a known composition. The compound target method, in which the elements to be alloyed are placed on top of the target in a specific ratio, and the method in which multiple targets are used at the same time are widely known.
[]) and (2) or (1) and (3) to obtain a desired film composition is widely practiced.

For example, as an example of case (2) above, Co-Fe film is sputtered using DC Competitive equipment, but Takahashi et al. "Film Thickness and Composition Distribution" Applied Physics Vol. 54, No. 3 (1985), pp. 242-2
As described in page 51 (hereinafter referred to as 1 Document 1), we are researching the relationship between controlling the alloy composition of the formed film and the in-plane composition uniformity of the substrate with respect to the arrangement of different materials on the target. Further, as for the metallurgical method described in (1) and (2) above, in the case of forming a film of Fe-Ni alloy using R, F, or magnetron type.

It is described in Japanese Patent Application Laid-Open No. 58-219724.

[Problem that the invention seeks to solve]

In the example of Document 1 of the above-mentioned prior art, in order to constitute an alloy with the target, the surface area ratio of the material placed on the target, the sputtering rate, the shape of the material placed on the target, the arrangement method, and the formation A method of controlling the composition of the formed film by examining the film composition and composition distribution and reducing the composition distribution using the method described above has been studied.

However, there is no study on the amount of composition variation depending on the frequency of target use, and furthermore, there is no mention of wear and tear on the material placed on the target. In order to perform the following control, it is necessary to accurately control the shape and position of the members placed on the target. Therefore, it is difficult to improve the accuracy of controlling the composition of the formed film using this method.

Furthermore, the method being investigated here is D.

C. This method is based on a competitive sputter method, and cannot be applied to R, F, and magnetron methods, which have a distribution in the amount of sputter etching on the target surface. R,F.

For the magnetron method, Japanese Patent Application Laid-Open No. 58-219724
According to this method, a member for controlling the composition is arranged on the main erosion area of the target to control the composition of the formed film and to obtain a formed film with a certain composition and a constant magnetostriction. This makes it possible to increase the frequency of target use. However, there is no mention of the distribution of the composition of the formed film within the plane of the substrate.
In addition, each time one composition control member wears out, one composition control member must be replaced with a new one, and the equipment must be operated continuously to form films on many substrates within a predetermined time. Further, as a result of subsequent studies by the present inventors, it became clear that as the frequency of target use increases, the range of composition fluctuations with respect to frequency increases. If you try to use the target within the width, the target life will be shortened,
There is a gap in the ability to improve target usage efficiency.

Additionally, when performing sputtering film formation using an alloy target with a composition close to the target formation film composition, the formation film composition and the target composition will generally differ, and the degree of this will depend on the type of alloy, and in some cases is 1wt% (weight%
) The above will also be different. Furthermore, even if the target composition is determined taking into account the amount of variation, the amount of composition variation will increase at the initial stage of target use and once the target has been used, resulting in variation in the composition distribution within the substrate surface. . Further, the amount of composition variation, the amount of composition distribution within the substrate plane, and the amount of composition variation due to the number of times of debossing vary among devices, and are not uniform even in devices having the same configuration.

Another possible method is to determine the target composition after taking into account the amount of variation mentioned above, and use that target for a certain period of time, but the analysis accuracy of the alloy target is ±0.
, 3 wt%, so this method cannot increase the control of the composition of the formed film beyond that value, and generally target conversion requires a large amount of time. It is difficult to control the composition of the formed film with high precision.

From the above, (+) it is necessary to control the composition of the formed film in some way, (2) to reduce the distribution of the composition within the substrate plane, and (3) the amount of variation in the composition of the formed film with respect to the frequency of use. It is necessary to make the size smaller. In particular, in the case of permalloy thin films used as the magnetic core material of thin-film magnetic heads, in order to control the magnetostriction constant, ±0,
Composition control of about 1 wt% is desired.

In view of such conventional needs, the object of the present invention is to
F. In an apparatus that uses the magnetron method, to control the target formed film composition with high precision, to reduce the distribution of the formed film composition within the substrate surface, and to reduce the amount of variation in the formed film composition with respect to the frequency of use. , thereby making the characteristics of the formed film that strongly depend on the composition of the formed film uniform within the substrate plane and stably obtaining a formed film with the same characteristics, and a method for producing a magnetic thin film alloy that can easily do the above. Our goal is to provide the following.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention arranges a target, which is a deposition material, and a substrate in a vacuum chamber.

In a method for producing a magnetic thin film alloy in which a magnetic thin film alloy having a target composition is produced on a substrate by R, F, magnetron sputtering method, an alloy material having a composition close to that of the target magnetic thin film alloy is placed on the target. and further placing a material (member) different from the alloy composition of the target on the target surface other than the main erosion area of the target to form a magnetic thin film alloy with the target composition on the substrate. It has characteristics.

[Effect]

In an R, F, magnetron sputtering device, a target with an alloy composition close to the alloy composition of the film to be formed is used, and a target member with a composition different from that of the target is placed outside the main erosion area of the target, and the target member is By adopting a method of controlling the composition of the formed film and the magnetic properties of the formed film by adjusting the composition of the formed film, a formed film having a uniform composition over a wide range can be obtained.

〔Example〕

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

First, the present invention will be explained in detail.

FIG. 1 is a layout diagram of composition control members in an R, F, magnetron sputtering apparatus showing an embodiment of the present invention.
FIG. 2 is a detailed configuration diagram of the magnetron sputter cathode shown in FIG. 1.

In this example, the device used in the study was R9F, had a magnetron cathode, and had a target size of 10 inches x 15 inches and a thickness of 9 tons. The material used in the study was permalloy (Fe-Ni), and the composition used was 82 to 83.5 wt% Ni. In addition, this device has a mechanism that can apply a magnetic field in one direction on the substrate surface for the purpose of forming a uniaxially anisotropic permalloy film.
It has a heater that heats the substrate. The spacing between the substrate and target was 75 thresholds. A glass substrate is used as the substrate, and the formed film thickness is about 1.5 mm.

The strength of the leakage magnetic field on the target surface was about 700 Gauss near the main erosion area (area where sputtering occurs selectively within the target surface) and about 80 Gauss at the center of the target.

As a result of the study, it was found that the composition of the formed film can be controlled by changing the area of the formed film composition adjusting member placed outside the main erosion area, but in order to make the formed film composition uniform within the substrate plane, It is better to arrange a member with a large area as much as possible inside the cathode and adjust its composition.Also, since it is a magnetron type cathode and a member for adjusting the composition of a ferromagnetic substance is provided, a member for adjusting the composition is provided. (
If the component (composition control member) is small, it cannot be placed well due to magnetic field leakage from the target surface.

Further, during sputter film formation, the temperature of the composition adjusting member increases due to ion bombardment, so it is necessary to make the thermal contact between the target material and the composition adjusting member as close as possible. From the above, as shown in FIG. 1, it is preferable to arrange a member as large as possible inside the main erosion area and to control the composition of the formed film by subtly changing its composition.

Furthermore, if the composition adjustment member is configured to be thick, the leakage magnetic field distribution on the target surface may change and the discharge may become unstable. It is necessary to set the optimal thickness by considering the lifetime of the target.

For the purpose of preventing discharge failure and improving thermal contact, it is preferable to make a groove on the target at the position where the one composition adjusting member is to be placed as shown in FIG. 2, and to place it there.

The operation of the magnetron sputter cathode and this embodiment will be explained with reference to FIG.

A magnetron sputtering cathode consists of a target l made of a deposited material, and a magnet 7 (an electromagnet may be used in some cases) that generates a magnetic field that focuses plasma near the target surface to effectively generate sputtering.
and a cooling water inlet port (housing) 8 through which cooling water flows from the back surface of the target in order to prevent the target temperature from rising due to ion bombardment.This cathode is placed in the vacuum chamber 5, and Ar gas is introduced, high frequency power is applied to the cathode, Ar gas plasma is generated, sputtering occurs on the target surface, and the target material is deposited on the substrate 4. On this occasion,
Due to the leakage magnetic field 6 generated on the target surface,
In order to focus the plasma and increase sputtering efficiency on the target surface, the sputter etch amount of the target 1 has a distribution on the target surface that depends on the leakage magnetic field strength. In particular, the area where the strongest leakage magnetic field is generated has a strong horizontal magnetic field strength, can effectively focus the plasma, and forms the main erosion area 2.

On the other hand, near the center of target l, the magnetic field stands in the vertical direction, and the magnetic field strength is also weaker than the main erosion area 2 (less than 1710), so the plasma is not effectively focused. A dependent amount of plasma is focused, and the center of the target 1 is also slightly etched by sputtering.

By the method described in Japanese Patent Application Laid-Open No. 58-219724, the main erosion area 2 on the target 1 is
When a composition control member is arranged and an attempt is made to control the composition of the formed film, the composition control member is exposed to high-density plasma, so that a certain composition control member was observed to be red hot. Further, since the main erosion area 2 is easily deformed, it is difficult to thermally uniformly arrange the individual composition control members in the main erosion area 2 after the main erosion area 2 has been deformed. Furthermore, the composition control member is subject to severe wear and tear, and the composition control member must be replaced every time it wears out.

In the present invention, the composition control member 4 is placed at the center of the target 1 where the amount of sputter etching is small.

As a result, the composition control member 4 is not exposed to high-density plasma, and the etch rate is slow, so the composition control member 4 needs to be replaced less frequently than when it is placed in the main erosion area 2. Finish.

On the other hand, in the case of sputtering using a single alloy target, segregation of the alloy composition near the target surface is observed due to sputtering. This is known as a segregation phenomenon of alloys due to ion irradiation, and is known to depend on ion concentration, target temperature, and ion energy.

The results of the studies conducted by the present inventors have revealed that the degree of segregation of the surface composition on the target 1 is different between the main erosion area 2 and other locations. It is thought that the changes in the amount of composition variation and the composition distribution within the substrate plane with respect to the frequency of use during the initial stage of target use and when Target 1 has been used sufficiently are caused by the compositional polarization on the surface of Target 1 and the composition ratio of sputtered atoms. However, the details are not clear (details will be discussed later).

However, the effect of surface composition segregation distribution due to ion bombardment on the surface of target 1 (main erosion area 2
(a phenomenon in which the surface composition differs between the main erosion area 2 and other parts), a composition control member 4 having the same composition as the main erosion area 2 where segregation has occurred is installed in areas other than the main erosion area 2. This can be improved by placing . Also,
Since it is thought that the cause of target composition segregation is the effect of ion bombardment, it is better to place the composition adjustment member (composition control member) in a place other than the main erosion area 2 where the effect of ion bombardment is small.
The degree of compositional segregation imparted to the composition adjustment member by ion bombardment is weak, and fluctuation factors can be reduced.

From the above, it is possible to arrange the composition control member 4 in a place other than the main erosion area 2, and also to arrange the composition control member 4 inside the main erosion area 2 depending on the arrangement of the target 1 and the substrate of a general device. It is clear that it is better to place 4.

In addition, the compositional segregation of target alloys due to ion bombardment depends on the type of alloy, and depending on the degree of compositional segregation,
It is clear that the composition of the composition control member must be determined.

The details of the above study results will be explained below.

First, the relationship between the formation of a formed film and the magnetostriction constant of the formed film was investigated. This relationship is shown in FIG. Here, the horizontal axis is the formed film Ni
The composition (wt%) is shown, and the vertical axis shows the magnetostriction constant.

Further, the film formation was measured by EDX. From FIG. 3, it is clear that in order to control the magnetostriction of the formed film to about 10-7, it is necessary to control the composition of the formed film within ±0.1 wt%. The difference between the target composition and the formed film composition changed to the Ni-rich side by about 1%.

Next, the magnetostriction constant distribution within the substrate plane was examined without placing the composition control member on the target. This distribution state is shown in FIG. Here, A is the case where nothing is placed on the target, and B is the case where the composition control member is placed in the middle of the target.

As shown in FIG. 4, it can be seen that the magnetostriction constant deviates largely to the positive side when the substrate is away from the center.

In order to investigate the cause of this, the surface composition of the target after use (after sputtering) was investigated by EDX.

At the same time, the composition of the target base material was also investigated. The results are shown in FIG. 5, where A indicates the target surface composition after sputtering and B indicates the target base material composition.

According to the results, the target surface composition has shifted to the Fe-rich side compared to the composition of the target base material, and furthermore,
It became clear that the main erosion area of the target was about 1% more Fe-rich than other parts. In addition, in the composition analysis by EDX, it is possible that the composition of about 1,000 parts of the target surface in the depth direction is averaged and measured, and the composition is measured by averaging the composition of about 1,000 parts in the depth direction on the target surface, and the composition is measured by averaging the composition of about 1,000 parts in the depth direction on the target surface. Since we are not measuring the exact composition of It is not always the case that the sputtered atoms will be emitted with the same surface composition ratio.

However, it was assumed that compositional variations on the target surface caused magnetostriction distribution in the plane of the substrate. Furthermore, it was thought that the distribution of segregation in the target surface composition was caused by the distribution of plasma concentration and the distribution of temperature on the target surface, but this is not clear.

Therefore, we conducted the following study. A composition adjusting member was placed in the main erosion area 2 on the target, and the distribution of the magnetostriction constant within the substrate plane was measured.

However, the magnetostriction distribution only increased and did not decrease.The composition control member 4 was placed at the center of the target 1 as shown in FIG. 1, and the in-plane magnetostriction constant distribution of the substrate was measured. The results are shown in FIG. 4B. The magnetostriction distribution became smaller. The target composition at this time was 83.5wt%
It is of N+ composition, and the composition control member 4 is 100x
One with dimensions of 150 x 2 tons and a composition of 80 wt% Ni was used.

Therefore, it has become clear that segregation on the target surface in the main erosion area 2 and other areas is one of the causes of the composition distribution within the substrate plane.

FIG. 6 is a diagram showing the difference between the maximum and minimum magnetostriction constant distributions within the plane of each substrate. Here, A is the case where only the target is used, B is the case where a composition control member is placed in the main erosion area of the target, and C is the case where the target has a composition in which the magnetostriction constant of the formed film is positive, and the composition control member is selected as the target. When the member is selected so that the magnetostriction constant is negative, the target is selected so that the formed film magnetostriction is negative, and the composition control member is selected so that the magnetostriction is positive. It shows. As is clear from FIG. 6, the magnetostriction constant distribution was the smallest in case D.

Next, in the above cases A, B, and D, the variation in the magnetostriction constant with respect to the number of times of film formation was investigated. However, the magnetostriction constant measurement position was at the center of the substrate, and in case B, the composition control member was replaced with a new one each time the measurement was performed. The results are shown in FIG. 7. In the case of B, as the number of times the film was formed increased, the magnetostriction constant shifted significantly in the positive direction, but in the cases of A and D, the shift was not so large.

However, the magnetostriction constant distribution at the beginning of the film formation number and 20
Comparing with the magnetostriction constant distribution when the film is deposited approximately 0 times, it is found that 2
The distribution was larger when the film was formed about 00 times.

From the above, considering the ease of controlling the formed film,
Method D is better, followed by method B. Sixth order: Considering magnetostriction fluctuations with respect to the number of film formations, methods A and D are better. Furthermore, when considering the composition distribution within the substrate plane, it is clear that method D is better, and therefore method D is the most excellent composition control method.

In addition, especially in the case of the permalloy magnetic thin film used in this study, the dependence and sensitivity of the magnetostriction constant on the composition of the formed film is strong, and when the film is formed under the same film formation conditions, the magnetostriction constant and the composition do not correspond. Furthermore, compositional analysis has a larger error due to measurement accuracy. This fact indicates that method A, that is, controlling the formed film composition while controlling the target composition with high precision, increases the magnetostriction constant of the formed film. It shows how difficult it is to control. Moreover, it was actually difficult.

Therefore, the present invention is an effective method for controlling film properties such as the magnetostriction constant of permalloy, which are very sensitive to the composition of the formed film.

In this example, a binary alloy was considered, but it is clear that the present invention can be similarly applied to a method for producing a ternary alloy. In addition, in this embodiment, the target composition and the composition of the composition control member must be determined after thorough consideration with respect to the target formation film composition. I mean,
This is because it is clear that it depends not only on the target material but also on the equipment. In addition, it is necessary to determine the size of the composition control member so that the composition distribution within the substrate plane is as small as possible and so as not to disturb the stable discharge of plasma on the target surface. Regarding the shape of the member, in the case of a rectangular target, a rectangular shape is preferable.

For round targets, those on a circular disk were chosen.

〔Effect of the invention〕

As explained above, according to the present invention, the composition of the formed film can be controlled with high precision, and the formed film can have a uniform composition over a wide area within the substrate surface, and the target life can be reduced. Since a formed film having a uniform composition can be obtained over a long period of time, for example, when creating a functional element using a magnetic thin film alloy, it is possible to improve the yield within the substrate surface. It is possible to improve the performance depending on the composition of the magnetic thin film alloy.

It is also effective in shortening downtime of the equipment, and has the effect of making it easier to configure mass production equipment.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a layout diagram of R, F, and composition control members in a magnetron sputtering apparatus showing an embodiment of the present invention, and Fig. 2 is a detailed configuration diagram of the magnetron sputtering cathode shown in Fig. 1. , Figure 3 is a diagram showing the relationship between the formation of a formed film and the magnetostriction constant of the formed film, Figure 4 is a diagram showing the magnetostriction constant distribution state within the substrate plane, and Figure 5 is a diagram showing the relationship between the target surface composition and Fe composition after sputtering. Figure 6 is a diagram showing the difference between the maximum and minimum magnetostriction constant distributions within the plane of each substrate, and Figure 7 is a diagram showing the state of variation in magnetostriction constant with respect to the number of times of film formation within the plane of each substrate. It is. 1: Target, 2: Main erosion area, 3: Composition control member, 4: Substrate, 5: Vacuum chamber, 6: Leakage magnetic field on target surface, 7. Magnet, 8: Cooling water introduction outlet. Figure 1 Figure 2 Figure 3 Composition of the formed film N1 (wt%) 1) Stain? ≦ Figure 6 A E CD No. 7
Figure + 1XI 2oO row (times) Number of times of film formation

Claims (6)

[Claims] 1. A target, which is a material to be adhered, and a substrate are placed in a vacuum chamber, and the R.I. F. In a method for manufacturing a magnetic thin film alloy in which a magnetic thin film alloy having a target composition is manufactured on a substrate by a magnetron sputtering method, an alloy material having a composition close to that of the target magnetic thin film alloy is used as the target, and Magnetism characterized by arranging a material (member) different from the alloy composition of the target on the target surface other than the main erosion area of the target, and forming a magnetic thin film alloy with the target composition on the substrate. Method for manufacturing thin film alloys. 2. 2. The method of manufacturing a magnetic thin film alloy according to claim 1, wherein the member disposed on the target surface is disposed inside a closed main erosion area. 3. The alloy composition of the target is selected so that the magnetostriction of the formed film is negative when the target is alone, and the composition of the member placed inside the main erosion area is selected so that the magnetostriction of the formed film is positive when the target alone has the composition. 3. A method for producing a magnetic thin film alloy according to claim 1 or 2, characterized in that a composite target is selected so as to have a magnetostriction of about 0, and a composite target is formed to form a magnetic thin film alloy with magnetostriction near zero. 4. The alloy composition of the target is selected so that the magnetostriction of the formed film is positive when the target alone is used, and the composition of the member placed inside the main erosion area is selected so that the magnetostriction of the formed film is negative when the target alone has the composition. 3. A method for producing a magnetic thin film alloy according to claim 1 or 2, characterized in that a composite target is selected so as to have a magnetostriction of about 0, and a composite target is formed to form a magnetic thin film alloy with magnetostriction near zero. 5. By setting the shortest distance in the inner dimension of the main erosion area to be at least larger than the substrate diameter, and further changing the area exposed to the target erosion side of the member placed inside the main erosion area, the formed film composition can be improved. Claim 3, characterized in that the
A method for producing a magnetic thin film alloy as described in . 6. A patent characterized in that the shortest distance in the inner dimension of the main erosion area is set to be at least larger than the diameter of the substrate, and further, the composition of the formed film is controlled by changing the composition of a member arranged inside the main erosion area. A method for manufacturing a magnetic thin film alloy according to claim 3.