JPH05250663A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having high magnetic characteristics and high sliding resistance. CONSTITUTION:In the production process of the magnetic recording medium, a cooling process (cooling room 5) to form a protective film at <=150 deg.C is provided between the process to coat a substrate with a magnetic thin film at >=200 deg.C high temp. and a process to coat the protective film such as carbon on the magnetic thin film. The coating process of the substrate consists of a charging room 1 for pallet 9 of magnetic disk substrates 8, shutter 11, heating room 2, sputtering room 3 having a target 13 for base coating, and sputtering room 4 for magnetic thin film, etc. The process to coat the magnetic thin film consists of a sputtering room 6 for the protective film and unloading room 7, etc. Thereby, the magentic thin film is formed at high temp., and magnetic characteristics (coercive force, squareness ratio, magnetic anisotropy, etc.,) can be maintained high. Since the protective film is formed at low temp., a hard film is formed, which improves sliding resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium such as a magnetic disk or a magnetic tape, and more particularly to a method for manufacturing a magnetic recording medium having good magnetic recording / reproducing characteristics and sliding resistance.

[0002]

2. Description of the Related Art Generally, a magnetic recording medium includes a substrate, a base film,
It is composed of a magnetic thin film and a protective film, and these films are continuously formed in a vacuum apparatus by using techniques such as vapor deposition, sputtering, and plasma CVD. In that case, for example, Japanese Patent Laid-Open No. 2-9
As disclosed in Japanese Laid-Open Patent Publication No. 016, the characteristics of the magnetic thin film such as coercive force, squareness ratio and magnetic anisotropy are improved by forming the magnetic thin film while heating the substrate temperature to a high temperature of 200 ° C. or higher. You can In addition, in production, the protective film is continuously formed following the formation of the magnetic thin film in consideration of productivity, so the temperature at the time of forming the protective film also remains high. .. However, the sliding resistance of the protective film tends to decrease as the film forming temperature increases.

[0003]

In the above-mentioned prior art, by heating the substrate temperature at the time of forming the magnetic thin film to a high temperature, excellent magnetic characteristics can be obtained. Since the temperature at which the protective film is formed is also high, it is not possible to obtain a protective film with sufficiently high hardness, and the sliding resistance (sliding resistance) of the protective film is It was found that there is a problem that the temperature decreases as the temperature rises. For example, when carbon is used as the protective film, it is considered that when the film forming temperature is high, a graphite structure is likely to be formed, but when the film forming temperature is low, an amorphous or diamond crystal structure appears and the hardness is increased. As described above, in the conventional technique, since the temperature condition at the time of forming the magnetic thin film and the temperature condition at the time of forming the protective film are contradictory in order to obtain the magnetic recording medium having good characteristics, It was difficult to obtain a product having excellent sliding resistance.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, to maintain the characteristics of the magnetic thin film such as coercive force, squareness ratio, magnetic anisotropy, etc. even in continuous film formation, and It is an object of the present invention to provide a method of manufacturing a magnetic recording medium that can obtain a magnetic recording medium having a protective film with excellent dynamic characteristics.

[0005]

In order to achieve the above object, the present invention provides a magnetic recording medium in which at least a magnetic thin film and a non-magnetic hard protective film for protecting the magnetic thin film are formed on a substrate. In the method, the film forming temperature of the hard protective film is lower than the film forming temperature of the magnetic thin film. For this reason, a cooling step is provided between the magnetic thin film forming step and the hard protective film forming step.

In a preferred example, the film forming temperature of the hard protective film is set lower than 150 ° C. (for example, the film forming temperature of the magnetic thin film is 200 ° C., whereas the film forming temperature of the hard protective film is 150 ° C.
Below (preferably below 100 ° C.).

In order to cool the magnetic recording medium in the cooling step,
It is provided with a cooling device (cooling chamber, cooling mechanism) for bringing the cooling plate close to the magnetic medium to cool the medium by radiant heat or for blowing a cooling gas directly onto the magnetic recording medium.

[0008]

The operation based on the above configuration will be described.

According to the present invention, the film forming temperature of the hard protective film is made sufficiently lower than the film forming temperature of the magnetic thin film, and specifically,
Since a cooling process is inserted between the magnetic thin film deposition process and the hard protective film deposition process, the magnetic thin film can be deposited at a high temperature and the protective film can be deposited at a low temperature. It is possible to obtain a magnetic recording medium excellent in both slidability characteristics.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a structural diagram of an in-line type sputtering apparatus used in the present invention, FIG. 2 is a sectional structural diagram of an embodiment of a cooling chamber, and FIG. 3 is a sectional structural diagram of another embodiment of the cooling chamber. Is. 1 to 3, 1 is a charging chamber, 2 is a heating chamber, 3 is a base film sputtering chamber, 4 is a magnetic film sputtering chamber, 5 is a cooling chamber, 6 is a protective film sputtering chamber, 7 is an extraction chamber, and 8 is A magnetic disk, 9 is a net-like substrate holding pallet, 10 is a solenoid valve, 11 is a shutter, 12 is an infrared lamp heater, 13 is a target, 14 is an argon gas pipe, 15 is a nitrogen gas pipe, 16 is a dry pump, 17
Is a cryopump, 18 is an exhaust pipe, 19 is an exhaust amount control valve, 20 is an inner chamber, 21 is a cooling block,
Reference numeral 22 is a refrigerant pipe, 23 is a pallet transport rail, 24 is a cooling gas pipe, and 25 is a cooling gas nozzle.

Example 1 In the in-line sputtering apparatus shown in FIG. 1 in which a cooling chamber 5 and a cooling mechanism were provided between the magnetic thin film sputtering chamber 4 and the protective film sputtering chamber 6, the film forming conditions for the base film and the magnetic thin film,
A magnetic disk is manufactured by setting the cooling condition and the film forming condition of the protective film as shown in FIG.

Here, the substrate has 5.25 inches of Ni--
Four P-plated aluminum substrates are used, four of them are mounted on the aluminum pallet 9 for holding the substrate, and continuous transfer film formation is performed. Here, the entire pallet including the substrate is called a work.

[0014] As shown in FIG. 1, and introducing the workpiece is first charged into a chamber 1, with a dry pump 16 and the cryopump 15, pulling a vacuum of 1 × 10- ⁵ Torr. After that, the shutter 11 is opened and the work is introduced into the heating chamber 2. Here, while the work is being heated using the infrared lamp heater 12, the cryopump 17 causes 3 × 10−
Draw a vacuum of ⁶ Torr or less. Before the next shutter is opened, argon gas is introduced into the heating chamber 12 and 2 mTorr.
After adjusting the gas pressure to r, the work is introduced into the base film sputtering chamber 13. Therefore, the base film, the magnetic thin film, and the protective film are formed in the chambers 3 to 6 under the conditions shown in FIG. For example, when the temperature of the heating chamber 2 is about 250 ° C., the temperature of the base film sputtering chamber 3 is about 230 ° C. and the temperature of the magnetic film sputtering chamber 4 is about 200 ° C. In this process, a shutter is not provided because continuous film formation is performed. However, since the gas pressure in each chamber may be different, the boundary between the chambers has a slit shape so that the gas pressure in each chamber can be maintained. In particular, since the gas pressure in the cooling chamber 5 is set high, for example, 40 mTorr in order to enhance the cooling efficiency, the gas pressure in the other chamber can be maintained by exhausting gas from the boundary between the chambers. It is like this. After the film formation is completed, the pressure is returned to the atmospheric pressure in the take-out chamber 7, and the film formation process is completed. The respective film thicknesses are about 10 μm for the Ni—P plated layer, 50 to 600 nm for the chromium underlayer film, 30 to 80 nm for the magnetic thin film, and about 10 to 60 nm for the protective film.

In the above process, condition 1 in FIG.
As shown by the curve, the film forming temperature of the protective film can be lowered by 50 ° C. or more as compared with the film forming temperature of the magnetic thin film.

Although FIG. 1 shows a continuous transfer film forming system, the same manufacturing process can be applied to a static film forming system in which each chamber is independent, such as a so-called Varian system. Can be done.

Embodiment 2 In Embodiment 1, a cooling mechanism as shown in FIG. 2 which is a cross-sectional view of the cooling chamber 5 in FIG. 1 is installed. That is, the cooling block 21 having the refrigerant pipe 22 is installed in the inner chamber 20 and cooled by water cooling or another refrigerant, and the cooling block is brought closer to the work conveyed by the pallet conveying rail 23 by 10 mm or less. By
It takes heat from the work and cools it. When this distance is 1 mm or less, the effect is remarkable.

At this time, in order to improve the cooling efficiency, the refrigerant pipe 22 and the cooling block 21 are preferably made of silver or copper having good thermal conductivity, but aluminum can also exert the effect. The refrigerant is preferably helium gas, liquid nitrogen or the like, but may be water.

Here, the cooling curve of the substrate when copper is used as the material of the refrigerant pipe and the cooling block, oil cooled to -20 ° C. is used as the refrigerant, and the distance between the work and the cooling block is set to 5 mm is shown in FIG. The condition 2 of No. 5 is shown.

Example 3 In this example, the cooling block 21 used in Example 2 was
Since I made it contact the pallet surface,
Further, the cooling efficiency can be improved. At this time,
As shown in FIG. 2, by making the thickness of the pallet 9 thicker than the thickness of the substrate of the disk 8, it is possible to prevent the cooling block from directly contacting the substrate and damaging the substrate surface.

The cooling block has a structure that can be brought into direct contact with or separated from the pallet by a driving device such as an air cylinder.

Fourth Embodiment In the third embodiment, cooling is performed by utilizing the heat conduction loss of the contact surface between the end face of the substrate and the pallet and the contact surface between the pallet surface and the cooling block. In order to further improve the cooling efficiency, the projection 21a is provided so that the cooling block contacts the innermost peripheral portion of the substrate. That is, the protrusion is brought into contact with the non-recording area near the center while avoiding the recording area of the disk 8. This allows
Since heat can be taken directly from the substrate, condition 3 in FIG.
The cooling curve is shown in.

When the cooling block contacts the substrate,
If there is rubbing, the substrate may be scratched, so it is preferable to cool the work in a stationary state. Further, a mechanism may be used in which the cooling block is moved so that the relative speed with respect to the work becomes zero.

Embodiment 5 In this embodiment, a cooling mechanism as shown in FIG. 3 is installed in the first embodiment. In other words, cooling gas such as argon
The magnetic medium is sprayed from the cooling nozzle 25 to the work through the cooling gas pipe 24 to cool the magnetic medium. At this time, the cooling gas is preferably an inert gas such as argon, helium or xenon, but a gas such as nitrogen or hydrogen may be used. Here, if a gas other than the argon gas is used, there is a possibility of mixing with a gas in another chamber, so it is preferable to provide shutters before and after the cooling chamber. A buffer chamber may be provided.

Further, the temperature of the cooling gas is conveniently room temperature, but it is preferable to cool it to a temperature lower than that because the cooling efficiency is improved.

In the sputtering apparatus of Example 1, 20 cone-flat type nozzles (one in which the flat circular bottom surface of the cone-shaped nozzle is an opening) were used, and the total gas flow rate was 200 sccm (Standard Cubic C).
The cooling curve of Condition 4 of FIG. 5 was obtained by setting the cooling curve to the conditioner per Minutes). Note that the higher the gas flow rate, the better the cooling efficiency, but if it is too high, dust is blown up and the life of the cryopump is shortened. It is necessary to minimize the flow rate.

According to the above embodiments, the sliding resistance of the protective film can be improved while maintaining the characteristics of the magnetic thin film. In FIG. 6, the film forming temperature of the magnetic thin film is kept constant at 200 ° C.
The result of the drag test when the film forming temperature of the protective film is changed variously is shown. In this test, as a means for evaluating the abrasion strength of the protective film, an alumina slider is pressed against the protective film with a spring load of 10 grams and reciprocated. According to this test, the number of reciprocations until the protective film is destroyed is improved by 2.5 times or more as compared with the case without cooling.

This is because the quality of the carbon film was changed, and the Raman spectrum (absorption spectrum by laser light) shown in FIG. 7 was 1350 cm- ¹ and 155.
When the intensity ratio of 0 cm ⁻¹ , I ₁₃₅₀ / I _1550, is taken, as shown in FIG. 8, the intensity ratio decreases as the film forming temperature decreases. This I ₁₃₅₀ is due to the graphite structure. A large strength ratio means that the graphite structure is large, and a small strength ratio means that the amorphous and diamond structures are large. This is in good agreement with the increase in film hardness, and it can be said that a carbon film having a strength ratio of 0.9 or less, preferably 0.8 or less is excellent in sliding resistance.

The magnetic recording media obtained in the above examples have the characteristics shown in FIG. 9 and were mounted on a head / disk assembly for evaluation. Was obtained, and good results were also obtained in terms of sliding reliability. In the above embodiments, the case where carbon is used as the protective film has been described, but the same can be applied to the case where ZrO ₂ , WC or the like is used as the protective film.

[0030]

As described above in detail, according to the present invention, since the film forming temperature of the hard protective film is set lower than the film forming temperature of the magnetic thin film, the magnetic recording / reproducing characteristics are maintained at sufficiently high performance. As it is, there is an effect that the strength of the hard protective film can be increased and the sliding resistance can be improved.

[Brief description of drawings]

FIG. 1 is a structural diagram of an in-line type sputtering apparatus used in the present invention.

FIG. 2 is a sectional structural view of an embodiment of the cooling chamber in FIG.

3 is a sectional structural view of another embodiment of the cooling chamber in FIG.

FIG. 4 is a diagram showing an example of setting manufacturing conditions according to an embodiment of the present invention.

FIG. 5 is a graph showing comparison of cooling efficiency according to cooling conditions.

FIG. 6 is a graph showing a comparison of sliding strength depending on a film forming temperature.

FIG. 7 is a Raman spectrum chart.

FIG. 8 is a graph of Raman spectrum intensity ratio comparison.

FIG. 9 is a diagram showing test results in comparison with an example of the present invention and a conventional example.

[Explanation of symbols]

 1 Preparation Room 2 Heating Room 3 Underlayer Sputtering Room 4 Magnetic Thin Film Sputtering Room 5 Cooling Room 6 Protective Film Sputtering Room 7 Extraction Room 8 Magnetic Disk 9 Substrate Holding Palette 10 Solenoid Valve 11 Shutter 12 Infrared Lamp Heater 13 Target 14 Argon Gas Piping 15 Nitrogen gas pipe 16 Dry pump 17 Cryopump 18 Exhaust pipe 19 Exhaust amount control valve 20 Inner chamber 21 Cooling block 22 Refrigerant pipe 23 Pallet transfer rail 24 Cooling gas pipe 25 Cooling gas nozzle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuichi Kojima 2880 Kokufu, Odawara-shi, Kanagawa Stock company Hitachi Ltd. Odawara factory (72) Inventor Yoshinori Honda 2880 Kunifu, Odawara, Kanagawa Hitachi Odawara Co., Ltd. Inside the factory (72) Inventor Masaki Oura 2880 Kozu, Odawara-shi, Kanagawa Stock company Hitachi Ltd. Odawara factory (72) Inventor Ryo Kitou, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Co., Ltd. (72) Inventor Yuichi Okazumi 292 Yoshida-cho, Totsuka-ku, Yokohama City, Kanagawa Prefecture

Claims (5)

[Claims] 1. A method of manufacturing a magnetic recording medium in which at least a magnetic thin film and a non-magnetic hard protective film for protecting the magnetic thin film are formed on a substrate, wherein a film forming temperature of the hard protective film is set to A method of manufacturing a magnetic recording medium, wherein the temperature is lower than the film forming temperature. 2. The method of manufacturing a magnetic recording medium according to claim 1, further comprising a cooling step between the step of forming the magnetic thin film and the step of forming the hard protective film. 3. The method of manufacturing a magnetic recording medium according to claim 1, wherein the film forming temperature of the hard protective film is lower than 150 ° C. 4. A cooling device for cooling the magnetic recording medium in the cooling step is provided, wherein the cooling device brings a cooling plate close to the magnetic recording medium to forcibly cool the magnetic recording medium by radiant heat. 4. The method for manufacturing a magnetic recording medium according to claim 2 or 3. 5. A cooling device for cooling the magnetic recording medium in the cooling step is provided, and the cooling device blows a cooling gas onto the magnetic recording medium to forcibly cool it. 2. The method for manufacturing a magnetic recording medium according to 2 or 3.