JPH05334648A - Magnetic recording medium, method and device for producing the same - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having high coercive force Hc and high Br.delta by forming plural CoCrTa films or other magnetic films while interposing Cr or Cr alloy films. CONSTITUTION:A Cr grounding layer 3 having 1,000Angstrom thickness is formed by sputtering on an Al substrate 1 with an NiP plating layer 2 formed on the surface and plural CoCrTa films 4 are formed on the grounding layer 3 while interposing Cr films 5 having 100Angstrom thickness. The films 4, 5 are formed with a static confrontation sputtering device, the background vacuum of the device is regulated to the level of 10<-8>Torr and the substrate 1 is degassed by heating to about 200-280 deg.C before sputtering. During sputtering, 3X10<-3>Torr is kept by introducing gaseous Ar and -300V bias is impressed on a substrate holder for holding the substrate 1. A Co alloy contg. 12 atomic % Cr and 2 atomic % Ta is used as a target for forming the CoCrTa films 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium having an improved coercive force, and a manufacturing method and apparatus for the same.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, a disk type magnetic recording medium has a NiP plating layer 2 formed on the surface of a substrate 1 made of a non-magnetic material such as aluminum, and then Cr or C.
Underlayer 3 of r alloy and CoCrTa layer 4 made of magnetic material
Are sequentially provided (see, for example, JP-A-3-4902).
No. 0). For the underlayer 3 and the CoCrTa layer 4, a film forming technique by a sputtering method is adopted, and in some mass-production type facilities, a substrate is a continuous treatment system in which the substrate passes through a sputtering chamber. Since the CoCrTa layer 4 constitutes a magnetic film layer, in addition to CoCrTa, CoCrT
aNi, CoCrTaPt, CoCrTaW, CoCr
In some cases, a Ni, CoCrNiPt, or CoCrNiW film was used.

[0003]

In such a magnetic recording medium, the coercive force Hc of the magnetic film layer is increased in order to increase the recording density.
However, at present, the coercive force Hc of CoCrTa film is limited to 1500 Oe.
In order to exceed this limit, attempts have been made to replace the magnetic film layer with a Pt-based alloy material and to apply a bias voltage to the substrate during sputtering.

However, in order to use a Pt-based alloy material as the magnetic material, a Pt-based alloy target is required, and the cost (50 times or more that of the Co-based) has risen, making it difficult to adopt.
Further, an attempt to apply a bias voltage to the substrate during sputtering was only able to improve the coercive force Hc to about 1800 Oe (in the case of the CoCrTa film), and the effect to that extent could not be expected. Furthermore, in a mass-production type equipment that uses a continuous processing method in which the substrate passes through the sputtering chamber,
Since the substrate holder moves, it is difficult to insulate from the ground potential and it is difficult to apply a stable bias voltage.

[0005]

The present invention has been made in view of the problems as described above, and is a magnetic recording medium in which a CoCrTa film or other magnetic film is formed on a substrate and has a high coercive force Hc. The purpose is to provide the medium.

The present invention also has such a high coercive force H.
It is also an object to provide a method and apparatus suitable for manufacturing the magnetic recording medium of c.

The magnetic recording medium of the present invention which achieves the above object is a magnetic recording medium in which a CoCrTa film or other magnetic film is formed on a substrate, wherein the CoCrTa film or other magnetic film sandwiches a Cr or Cr alloy film. It is characterized by multiple layers.

The CoCrTa film and other magnetic films are CoC.
rTa, CoCrTaNi, CoCrTaPt, CoC
rTaW, CoCrNi, CoCrNiPt, CoCr
It can be any film of NiW.

The CoCrTa film and other magnetic films may have any number of layers of 2 or more, but preferably 2 to 4 layers.

The method of manufacturing a magnetic recording medium according to the present invention is a method of manufacturing a magnetic recording medium by forming a CoCrTa film or other magnetic film on a substrate by a sputtering method. The alloy target of the film material and the Cr or Cr alloy target are alternately made to face stationary, and sputtering is performed at the time of stationary facing,
It is characterized in that a CoCrTa film or other magnetic film and a Cr or Cr alloy film are sequentially formed on a substrate.

As described above, it is desirable that the CoCrTa film and other magnetic films have 2 to 4 layers, and a Cr or Cr alloy film is sandwiched between the CoCrTa film and other magnetic films.

A bias voltage may be applied to the substrate during sputtering.

Next, the magnetic recording medium manufacturing apparatus of the present invention is a magnetic recording medium manufacturing apparatus in which a target and a substrate holder are installed in opposition to each other in a sputtering chamber, wherein the target is at least one of CoCrTa and others. A plurality of kinds of alloy targets made of magnetic material and at least one Cr or Cr alloy target, and the substrate holder is a holder for holding at least one substrate. It is characterized in that a drive mechanism for sequentially moving to a position facing one of the targets and stopping it is provided.

The target may be installed on one side of the substrate holder, but it is desirable that a plurality of types of targets are installed on both sides of the substrate holder so that a film can be formed on both sides of the substrate.

In such an apparatus, the target is
The substrate holders are arranged at equal intervals along the circumference, and the substrate holder is composed of a rotatable disk, and the substrate holders are provided at equal intervals along the circumference on which the target is arranged. It can have a certain configuration.

The substrate holder may be insulated from the ground potential and connected to a bias applying power source.

Further, a plurality of sputtering chambers are provided in series,
At least one of the sputtering chambers is provided with the above-mentioned structure (CoCrTa film or other magnetic film and Cr film).
Or a structure for depositing a Cr alloy film), and a transport mechanism for transporting the substrate holder is provided over all the sputtering chambers, and the other sputtering chambers are
It is also possible to form an underlayer or a surface protective film.

[0018]

According to the magnetic recording medium of the present invention, CoCrT
Since the a film and other magnetic films are formed in a plurality of layers, the film thickness of each layer can be reduced and the coercive force Hc can be improved. It is known that the relationship between the coercive force Hc and the film thickness of the CoCrTa film and other magnetic films tends to decrease as the film thickness increases, as in the case of the CoCrTa film shown in FIG. It is a thing.

When the film thickness of the CoCrTa film and other magnetic films is made thin, it is a value that influences the output characteristics during recording and reproduction.
Br · δ (Br is the residual magnetic flux density, δ is the film thickness) becomes small, and the reproduction output is reduced.
Since the a film and other magnetic films are formed as a plurality of layers to eliminate the decrease of δ, it is possible to maintain the output characteristics and improve the coercive force Hc at the same time.

When a CoCrTa film or other magnetic film and a Cr or Cr alloy film are sequentially formed on a substrate, the CoCrT film may be formed depending on the interval period of the film forming process and the atmosphere (gas type) to which the CoCrTa film or other magnetic film is exposed.
The a film and other magnetic films may be deteriorated and the squareness ratio in the magnetic history curve of the magnetic recording medium may be deteriorated. In this respect, according to the manufacturing method and the apparatus of the present invention, CoC is formed in one sputtering chamber at a short interval of about 1 to 10 seconds.
Since the rTa film and other magnetic films and the Cr or Cr alloy film can be sequentially formed, deterioration of the squareness ratio can be avoided.

Further, since the substrate is opposed to the target during sputtering during sputtering, the CoCrTa film and other magnetic films can be formed at a constant growth rate with respect to the thickness direction, and the film is uniform in the thickness direction. Can be Further, since the input power of each target can be controlled individually and independently, the film thickness can be adjusted with an accuracy of 10 angstroms or less.

[0022]

EXAMPLES First, a magnetic recording medium having a magnetic film CoCrTa film will be described. As shown in FIG. 1, an aluminum substrate 1 having a NiP plating layer 2 formed on the surface thereof
Then, a Cr underlayer 3 (1000 angstrom) was formed by sputtering, and a CoCrTa film 4 was formed thereon in a plurality of layers with a Cr film 5 (100 angstrom) interposed therebetween. The CoCrTa film 4 and the Cr film 5 were formed by a stationary facing type sputtering device described below, the background vacuum of the device was on the order of 10 ⁻⁸ Torr, and the substrate 1 was sputtered at about 200 to 280 ° C. before sputtering.
Degassed by heating to. Argon gas was introduced during the sputtering to 3 × 10 ⁻³ Torr, and a bias of −300 V was applied to the substrate holder holding the substrate 1. The target for forming the CoCrTa film 4 is C
A Co alloy containing 12 atm% r and 2 atm% Ta was used.

In order to improve the coercive force Hc and the change in Brδ, as shown in FIG. 7, one layer of CoCrTa layer 4 and two layers of CoCrTa layer 4 sandwiching a Cr film 5 are used.
A 4-layer structure was prepared. In any case, CoCrT
The film thickness of the a layer 4 was 270 angstroms in the case of two layers, 180 angstroms in the case of three layers, and 135 angstroms in the case of four layers so that the total thickness was 540 angstroms.

The coercive force Hc and Brδ of each magnetic recording medium were as shown in FIG. That is, by forming the CoCrTa layer 4 into a plurality of layers, the coercive force Hc is 2000 Oe or more,
The maximum was 2257 Oe. Improving the coercive force Hc is 1770 O only by applying a bias to the substrate side.
However, it was found that it was effective to divide the CoCrTa layer into a plurality of layers.

Br · δ is about 400 G · μ in any case.
It was found that it was substantially constant with m, and Br · δ could be kept constant by ensuring the total film thickness of the CoCrTa layer 4.

The relationship between the number of CoCrTa layers 4 and the coercive force Hc was maximum when the number of layers was three, and was lower when the number of layers was two and four.

Considering that the coercive force Hc is 2000 Oe or more, the allowable range of film formation that can be formed on the underlayer 3, the controllable film thickness of the CoCrTa layer 4, and the like, the number of CoCrTa layers 4 is Layers 2-4 were found suitable.

Next, an embodiment of an apparatus for manufacturing the above magnetic recording medium will be described. As shown in FIG. 3, the apparatus was such that a heating chamber A, a base sputtering chamber B, and a magnetic film sputtering chamber C were connected in series. A transfer mechanism 37 is installed along the continuous direction of the chambers so that the substrate holder 12 supporting the substrate can be sequentially transferred to the heating chamber A, the base sputtering chamber B, and the magnetic film sputtering chamber C. There is. An exhaust device 14 is installed in each chamber, and the heating chamber A and the underlying sputtering chamber B are adjacent to each other, the underlying sputtering chamber B and the magnetic film sputtering chamber C are adjacent to each other, and the outer wall and the magnetic layer of the heating chamber A are adjacent to each other. On the outer wall of the film sputtering chamber C, a gate valve 3 is provided which allows the substrate holder 12 on the transfer mechanism 37 to pass therethrough.
8 is installed.

As shown in FIGS. 4 and 5, each of the sputtering chambers B and C was constructed by installing a plurality of cathodes 13 and 13 on the side wall of the sputtering chamber 11. Argon gas or the like can be introduced into the sputtering chamber 11 constituting the sputtering chamber through a gas introduction system (not shown) to adjust the gas atmosphere to a predetermined pressure.

The substrate holder 12 is a disk-shaped member which is rotatably supported by a support leg 17 which is erected on a traveling member 15 traveling along the transfer mechanism 37 with an insulating material 16 interposed therebetween. Along 8 along the through holes 18 at equal intervals
18 is formed, and each through-hole part serves as a substrate holding part.
Along the inner periphery of the through hole 18 which is the substrate holding portion, the spring piece 1
9 and 19 are provided so that the circular substrate 1 can be held in the center of the through hole 18.

Couplings 21 and 22 are provided at both ends of the central support shaft 20 of the substrate holder 12, respectively. One coupling 21 is coupled to an output shaft 24 of a step rotation mechanism 23 installed on one side wall of the sputtering chamber 11, and the other coupling 22 is a bias applying power supply installed on the other side wall of the sputtering chamber 11. 25
Is connected to the output shaft 26 of.

The output shaft 24 of the step rotation mechanism 23 is provided with an insulating material 27 in the middle so that the tip portion is insulated. The step rotation mechanism 23 causes step rotation as shown by arrow 28, and As shown in FIG. 29, it is configured so that it can be moved back and forth to connect to or disconnect from the coupling 21.

On the other hand, the output shaft 26 of the bias applying power source 25
Is insulated from the ground potential by the insulating material 30 provided on the side wall, and moves forward and backward as indicated by the arrow 31 to move the coupling 22.
It is configured so that it can be connected to or disconnected from.

The shield plates 32, 3 are provided on both sides of the traveling portion of the substrate holder 12 so as to face the substrate holder 12.
2 is installed. The shield plate 32 is a rectangular plate body as shown in FIG. 5, and has openings 33 respectively formed in the central portions of the four side edges, and among the eight substrates 1 and 1 held by the substrate holder 12. Every other, expose four substrates 1,
The remaining substrate 1 can be covered.

The cathodes 13 and 13 installed on the side wall of the sputtering chamber 11 have openings 33 in the shield plate 32.
It is installed according to the position of. Each cathode 13
Is composed of a target 34 facing the substrate 1, a target holder 35, a cooling mechanism for the target holder 35, and a cathode main body 36 that accommodates a rotating magnet for applying a magnetic field to the sputtering space. The target 34 can be supplied with DC power or high-frequency power from a power source (not shown).

In the magnetic film sputtering chamber C, the four cathodes 13 and 13 installed on each side wall of the sputtering chamber 11 are the targets 34 of the upper and lower two cathodes 13 and are the Cr targets, and the two cathodes 13 on the left and right sides.
Target 34 is a CoCrTa alloy target,
In the base sputtering chamber B, the targets 34 of all the cathodes 13 were Cr targets.

In the heating chamber A, a heating mechanism 39 is installed on the side wall instead of the cathode 13.
The heating mechanism 39 uses an infrared radiation lamp or the like as a heat source, and is installed at each of the positions facing the substrate 1 supported by the substrate holder 12 (eight places in the illustrated embodiment).

A magnetic recording medium having the structure shown in FIG. 1 was manufactured by using the magnetic recording medium manufacturing apparatus configured as described above.

In each substrate holding portion of the substrate holder 12, 3.
The 5-inch substrate 1 was held and intermittently transferred to the heating chamber A, the base sputtering chamber B, and the magnetic film sputtering chamber C via the transport mechanism 37.

In the heating chamber A, the inside of the chamber is evacuated by the vacuum pump 14 and the substrate 1 is heated to about 200.degree.
Then, the substrate 1 was degassed. Since gas such as H ₂ O is released in the degassing process, the gate valves 38 and 38 are closed so that the gas does not flow into the sputtering chambers B and C.

After the degassing process is completed, the substrate holder 1
2 was transferred into the base sputtering chamber B, and a Cr film (1000 angstrom) was formed as a base layer 3 on the surface of the substrate 1 by sputtering. The time required for sputtering was about 8 seconds at 1 kW. In the base sputtering chamber B, 4 cathodes 13 are provided.
The substrate holder 12 has the substrate 1
Are arranged on the same circumference at equal intervals.
Therefore, the sputtering was performed twice by rotating the substrate holder 12 by 45 degrees.

The pressure of the sputtering chamber 11 was set to 3 × 10 ^-3 Torr by introducing Ar gas after evacuating to a vacuum of 10 ^-8 Torr as a background.

After the formation of the underlayer 3, the substrate holder 12
Was transferred to the magnetic film sputtering chamber C, and CoCrTa layers 4 and Cr layers 5 were alternately formed on the surface of the underlayer 3.

The CoCrTa layer 4 is formed by coating the substrate 1 with Co.
It goes without saying that the substrate 1 is opposed to the Cr target and sputtering is performed to form the Cr layer 4 so as to face the CrTa target and the Cr layer 4 is deposited so that each substrate 1 alternately faces the CoCrTa target and the Cr target. The rotating mechanism 23 was controlled, and the step rotating mechanism was stopped during sputtering to maintain the direct relationship between the substrate 1 and the target 34. Further, during the sputtering, a bias potential was applied to the substrate holder 12 via the bias applying power source 25. The pressure of the sputtering chamber 11 is the same as the above, and the sputtering chamber 1 is evacuated to the 10 ⁻⁸ Torr level.
Ar gas was introduced into 1 to adjust the pressure to 3 × 10 ⁻³ Torr.

Each substrate 1 is a CoCrTa target and Cr
Although various modes are conceivable for the step rotation sequence of the substrate holder 12 for alternately facing the target, for example, the substrate 1 shown by B in FIG. 5 faces the CoCrTa target at the position shown in FIG. Then, by repeating the step rotation 90 times by 4 times, the Cr target, the CoCrTa target, the Cr target, the CoC
A CoCrTa layer 4 of three layers can be formed so as to face the rTa target in order and sandwich two Cr layers 5 therebetween.

The film thickness of the CoCrTa layer 4 and the Cr layer 5 is controlled by the electric power introduced through the cathode 13 so that a predetermined film thickness can be obtained in the same sputtering time. In the case of the embodiment, the distance between the substrate 1 and the target 34 is 40 mm, the diameter of the target 34 is 152 mm, and CoC
180 Å of rTa layer 4 and 10 of Cr layer 5
When the thickness is set to 0 angstrom, 0.05 to 0.3 kw is applied to the CoCrTa target and 0.1 to 0.3 kw is applied to the Cr target, and the sputtering time of one layer of the CoCrTa layer 4 or the Cr layer 5 is increased. 1-10
Could be seconds. Therefore, it takes about 1 minute to sputter a total of 5 layers of 3 layers of CoCrTa layer 4 and 2 layers of Cr layer 5. The CoCrTa layer 4
If only one layer has a thickness of 540 angstroms, a power of about 0.7 kW and a time of about 8 seconds are required.

CoC deposited on 3.5 inch substrate 1
When the film thickness distribution characteristics of the rTa film and the Cr film were examined, it was as shown in FIG. In the figure, (a) is the distribution of the CoCrTa film,
(B) is the distribution of the Cr film. Radius 22 and 3
The film thickness was determined by measuring the film thickness at intervals of 45 degrees along the circumference of 2.42 mm. The average film thickness of both the CoCrTa film and the Cr film is ±
The distribution was within 5%.

Although the embodiments of the method and apparatus for manufacturing the magnetic recording medium of the present invention have been described above, the present invention is not limited to the embodiments. For example, CoCrTa target and Cr in the magnetic film sputtering chamber C
If at least one target is installed in the sputtering chamber 11, the manufacturing method of the present invention can be carried out. Further, if the number of substrates held in the substrate holder 12 is at least one, the manufacturing method of the present invention can be carried out. Furthermore, the substrate holder 1
2 is not limited to a disc-shaped one, but at least 1
The manufacturing method of the present invention can be carried out by holding a single substrate 1 and making it possible to move the substrate 1 between different types of targets via a linear motion mechanism.

The number of magnetic film sputtering chambers C is not limited to one, and two or more magnetic film sputtering chambers C are connected in series to form a CoCrTa layer 4 and a Cr film.
You may make it form the multilayer film of the layer 5.

In the embodiment, the magnetic film is CoCrTa and the target 34 is a CoCrTa alloy target, but CoCrTaNi, CoCrTaPt, CoC are used.
rTaW, CoCrNi, CoCrNiPt, or Co
The magnetic film of CrNiW can be similarly implemented by changing the target 34. The Cr target for the Cr layer 5 can also be a Cr alloy target, and the Cr layer 5 can be a Cr alloy layer.

[0051]

According to the present invention, high coercive force Hc and B
A magnetic recording medium of r · δ can be provided.

Further, since the sputtering of the magnetic film layer of CoCrTa or the like is performed while the substrate and the target are made to face each other statically, the magnetic film layer of CoCrTa or the like can be made uniform in the thickness direction.

Further, since sputtering of CoCrTa or other magnetic film layer and sputtering of Cr or Cr alloy layer can be performed at short time intervals, and each layer can be exposed to an atmosphere containing harmful gas, CoCrTa or other It is possible to prevent the deterioration of the magnetic film layer.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of a part of a magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a CoCrT magnetic recording medium according to an embodiment of the present invention.
It is a graph which shows the relationship between the number of a layers, and coercive force Hc.

FIG. 3 is a configuration diagram of an embodiment of a manufacturing apparatus of the present invention.

FIG. 4 is a schematic sectional view of a sputtering chamber of the example.

FIG. 5 is a view seen from line AA in FIG.

FIG. 6 is a graph of film thickness distribution characteristics of the apparatus of the example,
(A) is a graph of CoCrTa film distribution, and (b) is a graph of Cr film distribution.

FIG. 7 is an enlarged cross-sectional view of a part of a conventional magnetic recording medium.

FIG. 8: Coercive force Hc and CoCr in a magnetic recording medium
It is a graph which shows the relationship of the film thickness of a Ta film.

[Explanation of symbols]

 1 Substrate 2 NiP Plating Layer 3 Underlayer 4 CoCrTa Layer 5 Cr Layer 11 Sputtering Chamber 12 Substrate Holder 13 Cathode 14 Vacuum Pump 23 Step Rotating Mechanism 25 Bias Applying Power Supply 32 Shield Plate 34 Target 37 Transfer Mechanism 38 Gate Valve 39 Heating Mechanism

Claims (11)

[Claims] 1. A magnetic recording medium comprising a substrate on which a CoCrTa film or other magnetic film is formed.
A magnetic recording medium comprising a film or other magnetic films as a plurality of layers sandwiching a Cr or Cr alloy film. 2. The CoCrTa film and other magnetic films are made of Co.
CrTa, CoCrTaNi, CoCrTaPt, Co
CrTaW, CoCrNi, CoCrNiPt, CoC
The magnetic recording medium according to claim 1, wherein the film is any one of rNiW. 3. The CoCrTa film and other magnetic films are 2 to
The magnetic recording medium according to claim 1, which has four layers. 4. A method for producing a magnetic recording medium by forming a magnetic film such as a CoCrTa film on a substrate by a sputtering method, wherein the substrate is an alloy target of a magnetic film material and Cr or Cr alloy in one sputtering chamber. A method of manufacturing a magnetic recording medium, characterized in that a target is alternately made to stand still and sputtering is performed at the time of standing still, and a CoCrTa film or other magnetic film and a Cr or Cr alloy film are sequentially formed on a substrate. 5. A CoCrTa film or other magnetic film is used in the range of 2-4.
5. The method for manufacturing a magnetic recording medium according to claim 4, wherein the layer is a layer, and a Cr or Cr alloy film is sandwiched between CoCrTa films and other magnetic films. 6. The method of manufacturing a magnetic recording medium according to claim 4, wherein a bias voltage is applied to the substrate during sputtering. 7. In an apparatus for manufacturing a magnetic recording medium, wherein a target and a substrate holder are installed to face each other in a sputtering chamber, the target is at least one CoCr.
A plurality of kinds of alloy targets made of Ta or other magnetic material and at least one Cr or Cr alloy target are used. The substrate holder serves as a holder for holding at least one substrate. An apparatus for manufacturing a magnetic recording medium, comprising a drive mechanism for sequentially moving to a position facing one of the targets and stopping the position. 8. The magnetic recording medium manufacturing apparatus according to claim 7, wherein the targets are installed on both sides of the substrate holder. 9. The targets are arranged at equal intervals along the circumference, and the substrate holder is composed of a rotatable disk, and the target is arranged along the same circumference as the circumference on which the targets are arranged. 9. The magnetic recording medium manufacturing apparatus according to claim 7, wherein the substrate holding portions are provided at equal intervals. 10. The apparatus for manufacturing a magnetic recording medium according to claim 9, wherein the substrate holder is insulated from a ground potential and is connected to a bias applying power source. 11. A plurality of sputtering chambers are provided in series, and at least one of the sputtering chambers has a structure according to claim 7 or 8, and a transfer mechanism for transferring a substrate holder over all the sputtering chambers. An apparatus for manufacturing a magnetic recording medium provided with.