JPH03183022A - Magnetron sputtering method and production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To increase the leak components parallel with a target surface to expand a discharge region and to decrease the defects of film formation by specifying the leak magnetic flux density from the target to 200 to 400G in a magnetron sputtering method. CONSTITUTION:The inside of a vacuum chamber of an atmosphere contg. O2 is maintained under 4X10<-4> to 2X10<-3> Torr. A magnet 11 is disposed on the rear of the target 10 essentially consisting of Fe and a magnetic layer of a continuous thin film type essentially consisting of gamma-Fe2O3 is formed on a rigid substrate by reactive sputtering. The max. value of the magnetic flux density component parallel with the target surface is set at 200 to 400G to expand the region where magnetron discharge arises and to increase the efficiency of utilizing the target. Further, the durability of the magnetic layer and the less defects are compatibly obtd. when the relation between the electric power density PD per 1 piece of the target and the flow rate OGF is selected at OGF =(3.7+ or -0.8)PD-(3.90+ or -0.7); OGF>0.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a magnetron sputtering method and a method for manufacturing a magnetic recording medium.

<Prior Art> A hard type magnetic disk in which a magnetic layer is formed on a rigid substrate and a floating magnetic head are used in magnetic disk drives used in computers and the like.

Conventionally, coated magnetic disks have been used in such magnetic disk drive devices, but as the capacity of magnetic disks has increased, sputtering methods have been used because they are advantageous in terms of magnetic properties, recording density, etc. 2. Description of the Related Art Thin-film magnetic disks having a continuous thin-film magnetic layer formed by a vapor deposition method or the like have come into use.

Thin-film magnetic disks are made by plating an N1-P underlayer on an AI2-based disk-shaped metal plate, or by oxidizing the surface of this metal plate to form alumite. It is generally constructed by sequentially depositing a Cr layer, a metal magnetic layer such as Co--Ni, and a protective lubricant film such as C by sputtering.

However, a metal magnetic layer such as Co--Ni has low corrosion resistance and low hardness, causing problems in reliability. On the other hand, Japanese Patent Application Laid-Open Nos. 62-43819 and 63-17521
The magnetic thin film mainly composed of iron oxide as described in Japanese Patent No. 9 is chemically stable, so there is no fear of corrosion, and it also has sufficient hardness.

<Problem to be solved by the invention> A magnetic layer containing iron oxide as a main component is usually made of y-FezOs.
Alternatively, it is composed of γ-Fetus containing Co.

The γ-FezO□ magnetic layer is usually formed by a direct method or an indirect method.

As direct methods, direct neutralization methods, direct reduction methods, and direct oxidation methods are usually used.

In the direct neutralization method, Fe50<
This is a method of forming a FeJ4 film using a target and oxidizing it to obtain a γ-Fe, rs film.

The direct reduction method uses an α-Fetrs target to reduce Fem04 in an Ar gas atmosphere containing Ha gas.
This method forms a film and oxidizes it to obtain a γ-Fezes film.

In the direct oxidation method, reactive sputtering is performed using an Fe target in an Ar gas atmosphere containing 02 gas to form a Fe50+ film, which is then oxidized to form γ-Fe2O3.
This is a method for obtaining membranes.

In addition, in the indirect method, reactive sputtering is performed using an Fe target in an Ar gas atmosphere containing 02 gas to form an α-Fears film, and this is reduced to form an Fe
In this method, a 1g4 film is formed and further oxidized to obtain a γ-Fears film.

In any of these methods, magnetron sputtering is usually used because a high sputtering rate can be obtained.

In the magnetron sputtering method, a target is provided in a vacuum chamber into which an inert gas is introduced, and a magnet is provided on the back side of the target to generate a magnetron discharge in which an electric field and a magnetic field are perpendicular to each other near the target surface. In such a configuration, the electrons move in a continuous trajectory near the target surface, increasing the ion density and increasing the number of ions that collide with the target. The rate of deposition of is also increased.

Generally, in sputtering, the target is eroded as sputtering progresses, but in magnetron sputtering, the target is locally eroded.

FIG. 1 is a sectional view showing the main part of the magnetron sputtering apparatus, and the target 10 is eroded as shown.

The eroded region at this time corresponds to the region where the direction of the leakage magnetic field is approximately parallel to the target surface, but in conventional magnetron sputtering, this region is narrow and the efficiency of using expensive target material is low.

Also, depending on the atmosphere during sputtering, areas other than the eroded parts of the target surface may undergo changes due to oxidation, etc.
Sputtered particles may re-deposit, resulting in a surface-altered layer. As sputtering progresses, the depth of the eroded portion increases and its area increases.
The surface-altered layer emits bullets, and the foreign matter ejected from the bullets may mix into or adhere to the sputtered film.

However, since the magnetic thin film of the above-mentioned thin film type magnetic disk is mainly used for digital recording, extremely low film defects are required. For this reason, it is necessary to suppress the mixing and adhesion of foreign matter into the magnetic thin film to an extremely low level.

For example, when using the above-mentioned direct oxidation method to form a γ-FeaOsMi layer, reactive sputtering is performed using an Fe target in an Ar gas atmosphere containing O and gas, so the γ-FeaOsMi layer is formed in areas other than the eroded areas of the target surface. Lisback particles whose surfaces have been oxidized re-deposit, resulting in blackened areas.

As the sputtering is repeated, the depth of the eroded area increases and the area of the eroded area also increases, and this blackened area is also sputtered, and the blackened area becomes lumpy and the bullets come out. Foreign matter ejected from the bullets may enter or adhere to the Fe3On film deposited on the substrate, or these deposits may peel off from the surface of the Fe504 film after sputtering, resulting in film defects in these areas.

The present invention has been made under these circumstances, and utilizes a magnetron sputtering method that allows sputtered films with few defects and high target utilization efficiency, and a magnetic recording method having a continuous thin film type magnetic layer with few film defects. An object of the present invention is to provide a method for manufacturing a medium.

Means for Solving the Problems> Such objects are achieved by the following inventions (1) to (4).

(1) A sputtered film is deposited on the substrate surface by magnetron sputtering using a magnetron sputtering device in which a target is provided in a vacuum chamber, a magnet is placed on the back side of the target, and a substrate is placed facing the target surface. A magnetron sputtering method, characterized in that a maximum value of a component of magnetic flux density on the target surface in a direction parallel to the target surface is set to 200 to 400G.

(2) The inside of the vacuum chamber was heated to 4, OX 10-'Torr.
~2. The magnetron sputtering method according to the above (1), which is carried out while maintaining the pressure at OX 10-3 Torr.

(3) It has a step of forming a continuous thin film type magnetic layer mainly composed of γ-Fears on a rigid substrate, and in this step, a target mainly composed of Fe is used in an atmosphere containing 02 gas. A method for manufacturing a magnetic recording medium, characterized in that when performing reactive sputtering, this reactive sputtering is performed by the magnetron sputtering method described in (1) or (2) above.

(4) Power density P per target
D (Watt/am”) and O2 gas flow rate OGF (SC
CM) as OGF = (3,7 ± 0.8) PD (3,9 ± 0.7) and OGF > 0. A method of manufacturing the magnetic recording medium described above.

Effect> In the present invention, since the leakage magnetic flux density from the target is set to 200 to 400G in the magnetron sputtering method,
Of the magnetic field leaking from the target surface, the component substantially parallel to the target surface increases, and the area where magnetron discharge occurs expands. Therefore, the eroded area of the target is expanded, and the target utilization efficiency is increased.

Since the eroded region is expanded in this way, defects in the resulting sputtered film are reduced.

The magnetron sputtering method of the present invention is highly effective when applied to reactive sputtering, particularly reactive sputtering using O3 as a reactive gas.

For example, when forming a γ-Fetrs magnetic film by the direct oxidation method, a Fe504 film is formed using an Fe target in an Ar gas atmosphere containing 02 gas. A black mutant layer was formed on the target surface, and as sputtering progressed, this black mutant layer was ejected and mixed into or adhered to the sputtered film on the substrate, causing film defects.

However, according to the present invention, since the erosion region is wide from the start of sputtering, the formation of a black substance layer on the surface of the Fe target is prevented, and the incorporation of foreign substances into the FezO4 film is reduced.
Finally, a γ-FerOs magnetic layer with extremely few film defects is obtained.

Therefore, errors caused by film defects are significantly reduced in the magnetic recording medium obtained according to the present invention.

<Specific configuration> Hereinafter, a specific configuration of the present invention will be explained in detail.

The present invention is applied to magnetron sputtering.

FIG. 1 shows an example of the configuration of the main parts of a magnetron sputtering apparatus.

The magnetron sputtering device used in the present invention is not particularly limited, and for example, a normal magnetron sputtering device having a configuration as shown in FIG. 1 may be used.

In the configuration shown in FIG. 1, a target 10 is provided in a vacuum chamber (not shown) into which an atmospheric gas such as an inert gas or a reactive gas is introduced, and a magnet 1 is placed on the back side of the target 10.
1 is placed, and a substrate (not shown) is placed facing the surface of the target 10. Then, the target IO is used as a cathode, and an anode 12 is provided as shown in the figure, or a substrate or a vacuum chamber is used as an anode.

In such magnetron sputtering equipment, when an electric field is applied between the cathode and anode, a magnetron discharge is generated near the target surface where the electric field and magnetic field are orthogonal, and electrons move in a continuous trajectory near the target surface. do.

The inert gas is turned into plasma by the electrons, and the generated ions collide with the target surface to perform sputtering, and atoms ejected from the target are deposited on the substrate surface to form a sputtered film.

In the present invention, in such a magnetron sputtering method, the leakage magnetic flux density from the target surface is set to 200 to 40.
It is set to 0G, preferably 200 to 300G.

Here, the leakage magnetic flux density is the maximum value of the component of the leakage magnetic flux density in a direction parallel to the target surface, and is a value measured on the target surface.

Note that repeated sputtering erodes the target and creates recesses on the surface, but in such a case, the magnetic flux density is measured on the surface of the recesses.

Further, the magnetic flux density can be measured using a Gaussmeter using a Hall element or the like.

By setting the leakage magnetic flux density within this range, the proportion of magnetic flux in a direction substantially parallel to the target surface increases, and the region where magnetron discharge occurs is expanded.

When the leakage magnetic flux density is below this range, magnetron discharge is difficult to occur, and when it exceeds this range, the eroded area of the target is critically reduced.

The intensity of the leakage magnetic field during sputtering is preferably constant, but may vary within the above range.

In addition, the leakage magnetic flux density changes as the target is eroded by repeated sputtering, but in this case, in order to keep the leakage magnetic flux density within the above range, the power applied to the target, the usage time, etc. are monitored and the back surface of the target is It is preferable to adopt a configuration in which the magnetic field strength at the position can be changed.

In order to change the magnetic field strength on the back surface of the target, it is preferable to use an electromagnet as the magnet because it is easy to control, but there is also a configuration in which a permanent magnet is used as the magnet and the distance between the magnet and the target is controlled. You can also use it as

In the present invention, the strength of the leakage magnetic field is set to the above range, and further,
The gas pressure in the vacuum chamber, that is, the sputtering pressure, was set to 4.0.
XIO-'Torr~2. It is preferable to set it as Qx10-'Torr.

When the sputtering pressure is reduced in this manner, in addition to the effect of the low leakage magnetic field strength described above, the erosion area on the target surface is further expanded, and the contamination of foreign matter into the Fe504 film is significantly reduced.

When the sputtering pressure is less than this range, magnetron discharge is difficult to occur, and when it exceeds this range, further expansion of the eroded region cannot be expected.

The method for manufacturing a magnetic recording medium of the present invention will be described below as a preferred application example of the magnetron sputtering method of the present invention.

In the present invention, the above-described magnetron sputtering method is used when forming a continuous thin film type magnetic layer containing γ-Fears as a main component on a rigid substrate.

The continuous thin film type magnetic layer whose main component is γ-Felon is
As described above, it is formed by a direct method or an indirect method.

The direct method is a method in which a Fe3Oa film is first formed and then oxidized to obtain a γ-Fetus film.

As a method for forming a Fe504 film using the direct method,
As mentioned above, the direct oxidation method is carried out in an Ar gas atmosphere containing 02 gas using a target mainly composed of Fe, the direct reduction method is carried out in a reducing atmosphere using (1-Fezes), and the target Another example is the direct neutralization method using FexO4.

Among these methods, it is the direct oxidation method that is most likely to cause foreign matter to be mixed into or attached to the sputtered film, and therefore the present invention is preferably applied to the direct oxidation method.

Further, the direct oxidation method is preferable because sputtering can be easily controlled and the film formation rate is high.

In the present invention, when forming the Fe504 film using the direct oxidation method, the leakage magnetic flux density range and sputtering pressure (total pressure of Ar gas and 02 gas) range at the target surface are set to the above ranges. By performing reactive magnetron sputtering under such conditions, the formation of a black variant layer on the target surface can be suppressed, and a magnetic layer with extremely few defects can be obtained.

Note that in order to improve the durability of the magnetic layer, the power density per target P D (Watt/c
m”) and the 02 gas flow rate OGF (SCCM), OGF= (3,7±0.8) PD-(3,9
±0.7) and OGF>0.

By performing reactive sputtering under such conditions, the durability of the magnetic layer, especially the C8S durability, becomes extremely high.

02 When the gas flow rate and power density are in such a relationship, a black denatured layer is likely to occur on the target surface, and as a result, defects in the magnetic layer are likely to occur, but by applying the present invention, high durability and fewer It becomes possible to achieve both defects and defects.

Note that in the present invention, it is preferable that the 02 gas be introduced near the substrate.

Details of Fe1O+ thin film formation by the direct method can be found in the Journal of the Institute of Electronics and Communication Engineers '80/9 Vol. J63 (: NQ, 9
p, 609-616, and in the present invention, it is preferable to form the magnetic layer according to this.

Note that in the present invention, it is preferable to use a high frequency magnetron batter method.

Fe3On deposited by sputtering is γ-Fea
oxidized to rs.

This oxidation occurs at a partial pressure of 02 gas of about 0.05 to 0.8 atm.
The heat treatment may be carried out in an atmosphere with a total pressure of about 0.5 to 2 atmospheres, and it is usually preferable to carry out the heat treatment in the atmosphere.

The holding temperature during heat treatment is 200 to 400°C, especially 25°C.
The temperature is preferably 0 to 350°C, and the temperature holding time is
Preferably the time is 10 minutes to 10 hours, especially 1 hour to 5 hours.

Note that it is preferable that α-Fe2rs is contained in the magnetic layer containing γ-Fezes as a main component in order to improve durability. In order to keep the content of α-Fe2rs at an effective level for improving durability, the temperature increase rate should be set at 3.5 to 20'C/min, especially 5.0 to 12'C/min during the above heat treatment.
/ min is preferable.

Note that the temperature increase rate may be constant, gradually increased or decreased, or a plurality of temperature increase rates may be combined to increase the temperature to the holding temperature.

If necessary, C01TL, Cu, etc. may be added to the magnetic layer, and Ar, etc. contained in the film forming atmosphere may be contained.

Co is an effective element for adjusting coercive force. The content of Co in the magnetic layer is preferably such that it replaces Fe by 10 wt% or less. Further, in order to make the magnetic layer contain Co, a Fe target containing Co may be used.

The thickness of the magnetic layer is set at 50 mm in consideration of productivity, magnetic properties, etc.
It is preferable to set the number to about 0 to 3000 people.

In the indirect method, reactive sputtering is performed using an Fe target in an Ar gas atmosphere containing 02 gas to form an α-Fe2rs film, which is reduced to form Fe2rs.
504 film, and further oxidation is performed to obtain a γ-FaYO1 film. This indirect method, like the above-mentioned direct oxidation method, includes a step of sputtering a target containing Fe as a main component in an oxidizing atmosphere, and also
Since the amount of two gases is large, the present invention is extremely effective.

For a rigid substrate on which a magnetic layer is formed on the surface, the manufacturing process is simplified as there is no need to provide an underlayer, and it is also easy to polish and control the surface roughness. It is preferable to use glass because it can withstand heat treatment during the formation of the magnetic layer and to control its surface roughness.

As the glass, it is preferable to use tempered glass, particularly surface-strengthened glass obtained by chemical strengthening.

Furthermore, a lubricating film containing an organic compound, an inorganic protective film, or the like may be provided on the magnetic layer.

The magnetron sputtering method of the present invention is not limited to forming a magnetic layer of such a magnetic recording medium, but is also applicable to, for example, S i Oa, S i S N 4 , T
It is suitable for various uses using reactive sputtering, such as the formation of iN films. Furthermore, the effect of effectively utilizing the target can be achieved even when ordinary magnetron sputtering methods other than reactive sputtering are applied.

<Example> Hereinafter, the present invention will be explained in further detail by giving specific examples of the present invention.

[Formation of Fe3O4 Film] An aluminosilicate glass substrate with an outer diameter of 130 mm, an inner diameter of 40 mm, and a thickness of 1.9 mm was polished and further subjected to chemical strengthening treatment. The chemical strengthening treatment was performed by immersing it in molten potassium nitrate at 450°C for 10 hours.

Next, the surface of this glass substrate was smoothed by mechanochemical polishing. A polishing liquid containing colloidal silica was used for mechanochemical polishing.

The surface roughness Ra+ax of the glass substrate after polishing was 50 people.

A magnetic layer containing γ-Fetus as a main component was formed on the surface of the cleaned glass substrate by a direct oxidation method.

First, preliminary sputtering is performed in an Ar gas atmosphere, and F
e The oxide film on the target surface was removed. Then O2
A gas was introduced and reactive sputtering was performed to form a Fe50< film. Note that 08 gas was introduced near the substrate.

For this reactive sputtering, a magnetron sputtering apparatus having the configuration shown in FIG. 1 was used, and various Fe3O films were formed by changing the sputtering conditions. These Fe3O4
The thickness of the film was 2000 people.

Note that the thickness of the target was 3 mm.

Table 1 shows the leakage magnetic field strength of the target surface during sputtering (the maximum value of the component of the magnetic flux density measured on the target surface in the direction parallel to the target surface), the applied power density PD, O per target, and gas flow rate OGF. show.

Note that as sputtering progresses, the leakage magnetic flux density changes due to erosion of the target surface, but in this example, an electromagnet is used as the magnetic field generation source, and the leakage magnetic flux density is kept constant by changing the generated magnetic field strength. I kept it.

The surface of each FemO4 film formed in this way was examined at a magnification of 5
Observation was made using a 0x optical microscope, and the number of foreign particles present within a 1 cm x 1 cm area was measured at four arbitrary locations on the film surface, and the total was determined. The results are shown in Table 1.

[Formation of γ-Fears magnetic layer J Each Fe504 film shown in Table 1 below was heated in air for 310 min.
It was oxidized for 1 hour at .degree. C. to form a y-FexOxMi layer, and a magnetic disk was obtained.

For these magnetic disks, use the following magnetic head,
C8S durability was evaluated based on the following criteria.

1 eye 4 kiko = L top Vickers hardness 2200 kgf/■” Al250x
- After forming a thin film magnetic head element on a Tic substrate, it was processed into a magnetic head shape and attached to a support spring (gimbal) to produce an air bearing type floating magnetic head.

R+*ax of the magnetic head flying surface was set to 130 people.

The flying height can be adjusted to 0 by adjusting the slider width and gimbal load. I
I tried to make it look like J.J.

A C8S test was conducted at 25° C. and 50% relative humidity using the above magnetic head on a CS main silkworm ball.

C8S was performed by repeating the cycle shown in FIG. 2, and the number of times until the recording/reproducing output decreased to less than half of the initial level was measured, and the following 5-level evaluation was performed.

07 to 10,000 times or more ○: 50,000 times or more and less than 100,000 times Δ: 20,000 times or more and less than 50,000 times ×: 10,000 times or more and less than 20,000 times × When a reproduction test was carried out, it was confirmed that there was a lack of reproduction output corresponding to the above-mentioned film defect.

From the results of the above examples, the effects of the present invention are clear.

<Effects of the Invention> According to the present invention, a sputtered film with few defects can be obtained, and a magnetron sputtering method with high target utilization efficiency is used, and a continuous thin film type magnetic layer with few film defects and high durability is provided. A magnetic recording medium is realized.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of the main parts of a magnetron sputtering device. FIG. 2 is a graph showing one cycle of C8S. Explanation of symbols 10...Tagela 11...Magnet 12...Anode agent agent TDC Corporation Patent attorney Yo Ishii

Claims (4)

[Claims] (1) A sputtered film is deposited on the substrate surface by magnetron sputtering using a magnetron sputtering device in which a target is provided in a vacuum chamber, a magnet is placed on the back side of the target, and a substrate is placed facing the target surface. A magnetron sputtering method, characterized in that a maximum value of a component of magnetic flux density on the target surface in a direction parallel to the target surface is set to 200 to 400G. (2) The inside of the vacuum chamber is 4.0 x 10^-^4 Torr~
The magnetron sputtering method according to claim 1, wherein the magnetron sputtering method is carried out while maintaining the pressure at 2.0×10^-^3 Torr. (3) It has a step of forming a continuous thin film type magnetic layer mainly composed of γ-Fe_2O_3 on a rigid substrate, and in this step, a target mainly composed of Fe is used in an atmosphere containing O_2 gas. A method for manufacturing a magnetic recording medium, characterized in that when performing reactive sputtering, the reactive sputtering is performed by the magnetron sputtering method according to claim 1 or 2. (4) Power density PD per target
(Watt/cm^2) and O_2 gas flow rate OGF (SC
CM), the Fe_3O_4 film is formed by the reactive sputtering, with the relationship between OGF=(3.7±0.8) PD −(3.9±0.7) and OGF>0. A method of manufacturing a magnetic recording medium.