JP2001202618A - Method for manufacturing magnetic disk and sputtering device used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnetic disk which is capable of easily manufacturing protective films having excellent durability and corrosion resistance with extremely thin films and improving the yield in manufacturing and a sputtering device used for the same. SOLUTION: After a magnetic film or the like is formed on the surface of a substrate 15, the substrate is arranged to exist at the center of a pair of electrodes 13 arranged to face each other within a device body 11 of the sputtering device. A power source 17 is connected to both electrodes 13 and an AC power source is used for this power source 17, by which both electrodes 13 are alternately changed to anode and cathode at a prescribed frequency in such a manner that, if the one electrode 13 is the anode, the other electrode 13 is the cathode, and if the one electrode 13 is the cathode, the other electrode 13 is the anode. Targets 14 mounted at the surfaces of the electrodes 13 are sputtered, by which the protective films are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk used for an information recording apparatus, particularly a magnetic recording medium such as a hard disk, in which a non-conductive film is formed on a surface of a magnetic disk substrate by a sputtering method. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Conventionally, a magnetic disk used for a magnetic recording medium as described above has a plurality of films, such as a base film, sequentially formed on the surface of a substrate for a magnetic disk, and then a magnetic film is formed on the surface. It is produced by forming a film. When information is written to or read from the magnetic film by a magnetic head moving while flying above the magnetic disk, foreign matter may enter between the magnetic head and the magnetic film and damage the magnetic film. . Further, since the magnetic film is made of metal, it may be corroded by oxidation or the like depending on the use environment. Further, the movement of the magnetic head becomes unstable due to the frictional force generated between the magnetic head and the magnetic film, and the magnetic head may collide with the surface of the magnetic film. In order to prevent such damage, oxidation and the like of the magnetic film, a protective film as a non-conductive film having abrasion resistance, impact resistance and corrosion resistance is formed on the surface thereof. This protective film is formed to be an extremely thin film by a sputtering method using a sputtering device in order to shorten the distance between the magnetic film and the magnetic head and improve the recording density of the magnetic disk.

[0003] A sputtering apparatus includes a pair of electrodes disposed opposite to each other in a main body of the apparatus, and a chamber wall disposed so as to surround these electrodes. A substrate on which a magnetic film is formed is supported between the two electrodes. Have been. Then, when a process gas such as argon gas is introduced into the apparatus body in a sealed state, and a negative voltage is applied to both electrodes using a direct current (DC) power supply, glow discharge is performed using both electrodes as cathodes and the chamber wall as anodes. Then, the process gas is turned into plasma between the two electrodes. At this time, positive ions in the plasma collide with a target attached to the electrode surface, and the target surface is sputtered, and the sputtered target component adheres to and deposits on the magnetic film surface, thereby forming a protective film. You.

[0004]

However, according to the sputtering method, the target component may adhere to the surface of the magnetic film as well as the surface of the target and the surface of the chamber wall to form a film. When a DC power supply is used in this state, if the film formed on the surface of the target and the chamber wall is non-conductive, the film is charged with a negative charge or a positive charge, and an arc is eventually generated. Due to this arc, the plasma generation between the two electrodes becomes unstable, and a part of the target melts due to thermal collision by arcing and adheres to the substrate as droplets. The non-conductive film deposited in the non-erosion region of the above may adhere to the substrate due to thermal shock at the time of dielectric breakdown due to the arc.

When an extremely thin protective film is formed in such a situation, the yield in manufacturing a magnetic disk is reduced due to foreign matter adhering to the protective film, and at the same time, a target component is deposited on the surface of the magnetic film. Magnetic disks are not deposited uniformly because the hardness of the protective film decreases and the wear resistance decreases, or the film density is insufficient and micropores are formed on the surface of the protective film to reduce the corrosion resistance. There was a problem that the quality of the product deteriorated. In addition to the sputtering method, there is a method of forming a protective film by a chemical vapor deposition (CVD) method. In the case of an insulating substrate in the CVD method, a conductive film must be further provided on the surface of the substrate. However, there has been a problem that the manufacturing time becomes longer and it is difficult to reduce the manufacturing cost.

The present invention has been made by paying attention to the problems existing in the prior art as described above. The objective is to provide a method of manufacturing a magnetic disk capable of easily manufacturing a non-conductive film excellent in durability and corrosion resistance with an extremely thin film, and improving the yield at the time of manufacturing. It is to provide a sputtering device to be used.

[0007]

In order to achieve the above object, the invention of a method for manufacturing a magnetic disk according to the present invention provides a method for manufacturing a magnetic disk, comprising the steps of: forming at least a magnetic film on a surface of a substrate; A method for manufacturing a magnetic disk in which a non-conductive film is formed by sputtering using a sputtering device, wherein the non-conductive film is formed using a sputtering device having an electrode that is inverted so that the polarity is reversed. It is characterized by the following.

According to a second aspect of the present invention, there is provided a magnetic disk manufacturing method according to the first aspect, wherein at least one set of a pair of opposed electrodes is provided in the sputtering apparatus. A substrate is arranged between the counter electrodes, and the non-conductive film is formed by changing the polarities of the pair of electrodes constituting the counter electrode so as to be inverted.

According to a third aspect of the invention, there is provided a magnetic disk manufacturing method according to the second aspect, wherein one of the counter electrodes is an anode if the other electrode is an anode, and the other electrode is a cathode. In the case of a cathode, the two electrodes are changed so as to have different polarities so that the other electrode becomes an anode.

According to a fourth aspect of the present invention, in the method of the second aspect, if one of the counter electrodes is an anode, the other electrode is also an anode, and the other electrode is an anode. In the case of a cathode, the two electrodes are changed so as to have the same polarity so that the other electrode is also a cathode.

According to a fifth aspect of the present invention, in the method of manufacturing a magnetic disk according to any one of the first to fourth aspects, the polarity of the electrode is inverted at a frequency of 1 to 100 kHz. It is assumed that.

According to a sixth aspect of the present invention, a non-conductive film of a magnetic disk having at least a magnetic film on a surface of a substrate and a non-conductive film formed on the magnetic film is formed by sputtering. , Comprising an electrode that reverses the polarity so that the polarity is reversed.

[0013]

(First Embodiment) A first embodiment of the present invention will be described in detail below.

The magnetic disk has a disk-shaped substrate, a seed layer, an underlayer, and a magnetic film formed sequentially from the surface of the substrate, and a protective film as a non-conductive film formed on the surface of the magnetic film. It is made from. Further, a lubricating layer made of a lubricant such as perfluoropolyether may be formed on the surface of the protective film.

The substrate is made of an inorganic material, such as soda lime glass, aluminosilicate glass,
It is preferable to use a non-magnetic material such as glass such as borosilicate glass, crystallized glass other than glass, ceramics, metal such as aluminum, or a material having ferrimagnetic or ferromagnetic properties. The substrate material having ferrimagnetism and ferromagnetism is based on the above-mentioned inorganic material and an organic material such as a synthetic resin as a base material. It is obtained by dispersing a magnetic material such as a ferrimagnetic material such as a magnetic material or ferrite. Among the above materials, glass is preferable as a substrate of a magnetic disk because it has higher rigidity than aluminum and does not have a possibility of deformation of the substrate due to impact.

The seed layer, the underlayer, and the magnetic film are made of metal as their materials, and are formed by a sputtering method or a chemical vapor deposition (CVD) method. Specifically, a nickel (Ni) -aluminum (Al) layer as a seed layer, a chromium (Cr) -molybdenum (Mo) layer as an underlayer, and a cobalt (Co)-layer as a magnetic film.
Platinum (Pt) -chromium (Cr) -tantalum (Ta) films and the like can be mentioned.

The protective film is formed on the surface of the magnetic film by a sputtering method using a sputtering device described later. As the material of the protective film, a material having high durability is preferable so as to withstand an impact force when the magnetic head lands. In addition, in order to prevent the magnetic film formed of the metal from being oxidized, those having high corrosion resistance are preferable. As a protective film satisfying these conditions, a carbon (C) film, a hydrocarbon (CH) film,
Examples thereof include a film of silicic acid (SiO ₂ ) and a film of silicon carbide (SiC). In this embodiment, a hydrocarbon film is used as the protective film.

Next, a sputtering apparatus for forming the protective film will be described. As shown in FIG. 1, an apparatus main body 11 constituting the sputtering apparatus is formed in a rectangular box shape, and a space inside the apparatus main body 11 is a film forming chamber 12. In the center of the film forming chamber 12, a pair of electrodes 13 are disposed facing each other with a predetermined distance therebetween, and these electrodes 13 constitute a counter electrode. A chamber wall and a shield plate (not shown) are provided in the film forming chamber 12 so as to surround the pair of electrodes 13. Each electrode 1
A target 14 made of carbon, which is a material of a protective film, is adhered to the inner surface of each of the substrates 3. A substrate 15 having a magnetic film formed on its surface is supported at the center of both targets 14 so that the surface of the magnetic film, that is, the surface on which the protective film is formed, faces the target 14.

A plurality of gas introduction pipes 16 are connected to the apparatus main body. Then, the film forming chamber 12 is sealed while the substrate 15 is accommodated in the apparatus main body 11, and a process gas is introduced from the gas introduction pipe 16 into the film forming chamber 12. Examples of the process gas include an argon (Ar) gas, a mixed gas of Ar and methane (CH ₄ ), and a mixed gas of Ar and hydrogen (H ₂ ). Gas inlet pipe 16
Is connected to a flow controller (not shown) to adjust the supply amount of the process gas, the mixed concentration, and the like. Further, a vacuum exhaust pump (not shown) is connected to the apparatus main body 11, and the inside of the film forming chamber 12 is depressurized by exhausting process gas, air, and the like from the inside of the film forming chamber 12 that is sealed.

A power supply 17 provided outside the apparatus main body 11 is connected to both electrodes 13. As the power supply 17, an alternating current (AC) power supply whose output frequency is adjustable is used. By applying a positive or negative voltage to each electrode using this AC power source, one of the electrodes 13 becomes an anode (anode).
Then, the other electrode 13 becomes a cathode (cathode), and if one electrode 13 is a cathode, the other electrode 13 becomes an anode so that both electrodes 13 are changed to have different polarities at a predetermined frequency. Poled. Then, a glow discharge is generated between the two electrodes 13 to which the voltage is applied, and the process gas is turned into plasma by the glow discharge.
Note that a direct current (DC) power supply can be used as the power supply, but in this case, a polarity converter that converts a voltage output from the DC power supply into a positive voltage or a negative voltage at predetermined intervals is connected, and the output is connected. It is necessary to change the polarity.

The polarity of the electrode 13 is preferably inverted at a frequency of 1 to 100 kHz. When the polarity of the electrode 13 is inverted at a frequency lower than 1 kHz, the effect of removing the positive charges accumulated on the non-conductive film deposited on the non-sputtered region (non-erosion region) on the surface of the target 14 is weakened, and the arc is reduced. And glow discharge becomes unstable. Further, when the frequency is inverted at a frequency higher than 100 kHz, the driving of the power supply 17 becomes unstable, so that the generation of the glow discharge between the two electrodes 13 becomes unstable.

Next, a method for forming a protective film using a sputtering apparatus will be described. As shown in FIG. 1, after a seed layer, an underlayer, and a magnetic film are formed on the surface of the substrate 15 in that order from the surface side of the substrate 15 by a CVD method or a sputtering method, the substrate 15 is placed in the apparatus body 11 of the sputtering apparatus. At the center between the two electrodes 13. Subsequently, Ar gas, C
While introducing H ₄ gas and H ₂ gas, these process gases, air and the like are exhausted by a vacuum exhaust pump, and the inside of the film forming chamber 12 is depressurized. When a positive or negative voltage is alternately applied to each of the electrodes 13 by an AC power supply, the two electrodes 13 alternately change to a cathode and an anode at a predetermined frequency, and a glow discharge is generated between the two electrodes 13 in due course. The Ar gas in the film forming chamber 12 enters a plasma state.

In this state, at the moment when one of the electrodes 13 becomes a cathode, argon ions (Ar
⁺ ) Moves toward the cathode side. The Ar.sup. ⁺ Ion collides with the surface of the target 14 during its movement, sputters the target 14 and repels carbon (C) atoms as target components. The repelled C atoms react with the CH ₄ derivative or H ₂ in the process gas to become hydrocarbons, which are non-conductive substances. The hydrocarbons adhere to the surface of the magnetic film and are deposited on the surface of the magnetic film. A protective film is formed on the surface of the cathode 15 on the cathode side.

When the protective film is formed, hydrocarbons adhere to the non-erosion region of the target 14, and a hydrocarbon film is formed also in the non-erosion region. This film accumulates Ar ⁺ ions on its surface and is charged to a positive charge. When the amount of charge exceeds a predetermined amount, it reaches a dielectric breakdown region, and the positive charge on the film surface and the negative charge on the target 14 surface Attempt to generate an arc through the interior of the membrane. Here, the dielectric breakdown region is defined by the coulomb amount of electric charge accumulated on the surface of the insulating film and the thickness of the insulating film since the strength of the dielectric breakdown is defined in kV / mm. . In addition, depending on the amount of positive charges and the thickness of the film, that is, the distance between the positive charges and the negative charges, the positive charges on the surface of the film and the negative charges on the surface of the target 14 pass through the inside of the film. Without trying to generate an arc. However, at the moment when the electrode 13, which was the cathode, became the anode, the electrons in the plasma were attracted to the anode, and the accumulated Ar ⁺
By removing the ions, the accumulation of Ar ⁺ ions on the surface of the film in the non-erosion region is suppressed.

The protection films are formed on both surfaces of the substrate 15 by reversing the polarity of the electrodes 13 so that their polarities are alternately inverted at a predetermined frequency. The formed protective film is a dense film with few defects such as micropores on the surface.

Here, the reason why the protective film is a dense film with few defects will be described. Generally, when a substrate is placed in a floating state at the center of a pair of cathodes facing each other, a sputtered target component adheres to the substrate surface, and at the same time, electrons are accumulated and negatively charged, thereby generating a self-bias. . Since this self-bias is a negative bias, Ar ⁺ ions in the plasma are attracted to and collide with the substrate surface. Since the collision of the Ar ⁺ ions with the substrate surface occurs simultaneously with the attachment of the sputtered target component, the target component moves (migrate) on the substrate surface by the energy at the time of the collision. With this migration,
The target component is rearranged to fill the defect. This phenomenon is called an ion assist effect, and a film formed by the ion assist effect is a dense film with few defects.

When a positive voltage or a negative voltage is alternately applied to the opposing electrodes 13 to form an anode and a cathode as in the present invention, electrons and Ar are collected between the electrodes 13 and the collision probability of these electrons and Ar is increased. Increase. Then, since the density of Ar ⁺ ions and electrons in the plasma increases, the potential of the self-bias generated on the surface of the substrate 15 increases, and the number of Ar ⁺ ions existing near the substrate 15 also increases. For this reason, when both the electrodes 13 are alternately used as an anode and a cathode, it is considered that the above-described ion assist effect is largely obtained.

When the frequency for reversing the polarity is increased, electrons move between the two electrodes 13 following the frequency, while Ar ⁺ ions having a larger mass than the electrons follow the frequency. It becomes impossible to move between the electrodes 13. By controlling the amount of movement of the Ar ⁺ ions to adjust the frequency based on this idea, Ar ⁺ ions and it is possible to increase the probability of collision with the surface of the substrate 15, it can also be drawn larger ion assist effect It is considered to be. However, if the collision energy of Ar ⁺ ions with respect to the substrate 15 is too large, the protective film formed on the surface of the substrate 15 may be sputtered, so that fine adjustment of the frequency is required.

The effects exerted by the first embodiment will be described below. By alternately reversing the polarities of a pair of electrodes 13 disposed opposite to each other in the apparatus main body 11 of the sputtering apparatus,
Since abnormal discharge can be reduced and the quality of the protective film can be improved, an extremely thin, high-quality protective film with excellent durability and corrosion resistance can be easily manufactured, and the production yield can be reduced. Can be improved.

By alternately inverting both electrodes so as to have different polarities, even if the material of the substrate 15 is a non-conductive material such as glass, for example, the self generated on the surface of the substrate 15 by plasma The bias can effectively extract the ion assist effect. For this reason, a dense protective film with few defects such as micropores can be formed on the surface, and the film quality can be improved easily and at low cost.

By setting the frequency for inverting the polarity of the electrode 13 within the range of 1 to 100 kHz, both electrodes 1
3 can be stably performed. (Second Embodiment) Hereinafter, a second embodiment of the present invention will be described in detail. The description of the second embodiment will focus on the differences from the first embodiment.

In the sputtering apparatus of the second embodiment, if one of the pair of electrodes 13 is an anode, the other electrode 13 is also an anode, and the other
If 3 is a cathode, both electrodes 13 are configured to change to the same polarity at a predetermined frequency so that the other electrode 13 also serves as a cathode.

In the sputtering apparatus according to the second embodiment, when a positive or negative voltage is simultaneously applied to the pair of electrodes 13 by an AC power source, both the electrodes 13 simultaneously change to a cathode or an anode at a predetermined frequency, and eventually both electrodes 13 A glow discharge is generated between the electrodes 13 and the film forming chamber 12
Ar gas inside is in a plasma state.

At this moment, when both electrodes 13 become cathodes, Ar ⁺ ions move toward both cathodes, the target is sputtered, and protective films are simultaneously formed on both surfaces of the substrate 15. In addition, Ar ⁺ ions accumulated in the film in the non-erosion region on the surface of the target 14 are neutralized at the moment when both electrodes 13 become anodes.

When both electrodes 13 are changed so as to have the same polarity, the chamber wall of the apparatus main body 11 and the shield plate function as an anode at the moment when both electrodes 13 become cathodes. At this time, electrons in the plasma are accumulated on the chamber wall and the shield plate. Electrons accumulated in the chamber wall and the shielding plate is to optimize the frequency at which the polarity of the electrodes 13 is reversed, by moving Ar ⁺ ions to the chamber wall and the shielding plate by adjusting the amount of movement of the Ar ⁺ ions Static electricity is removed.

Therefore, according to the sputtering apparatus of the second embodiment, the protective films can be simultaneously formed on both surfaces of the substrate 15.

[0037]

The first embodiment will be described more specifically with reference to examples and comparative examples. It should be noted that the present invention is not limited to these embodiments. (Example 1) A Ni-Al seed layer was sequentially formed on a surface of an aluminosilicate glass substrate by sputtering.
A Cr-Mo underlayer and a Co-Pt-Cr-Ta magnetic film were formed. Next, a protective film was formed on the surface of the magnetic film by sputtering in an atmosphere of a mixed gas of Ar and CH ₄ . Use an AC power source for the sputtering device,
The polarity of both electrodes was reversed at a frequency of 40 kHz. This was used as a sample of Example 1. (Comparative Example 1) A Ni-Al seed layer was sequentially formed on the surface of an aluminosilicate glass substrate by sputtering.
A Cr-Mo underlayer and a Co-Pt-Cr-Ta magnetic layer were formed. Next, a protective film was formed on the surface of the magnetic film by sputtering in an atmosphere of a mixed gas of Ar and CH ₄ . A DC power supply was used as a power supply for the sputtering apparatus. This was used as a sample of Comparative Example 1. (Evaluation of film quality) CH _{4 in a} mixed gas of Ar and CH ₄
The magnetic disks of Example 1 and Comparative Example 1 were manufactured with various concentrations of the gas. By measuring Raman scattered light with a Raman spectrophotometer on the thus-obtained protective film of the magnetic disk, sp2 bonds and sp2 in the film are measured.
The ratio of three bonds, Id / Ig and g peak position, were determined. The results are shown. Based on the results, optimum conditions for forming the protective film were obtained.

Here, Id / Ig and g peak positions will be described. When the hydrocarbon film is measured with a Raman spectrophotometer, a d peak (di) having a peak near 1350 cm ^-1 is obtained.
two peaks, a peak band at about 1570 cm ⁻¹ and a g-peak (graphite band) having a peak at about 1570 cm ⁻¹ . The heights of the d and g peaks from the baseline are called Id and Ig, respectively.
From the paper which the present inventors referred to when evaluating the film quality from the Id / Ig and g peak positions, it is most preferable to prepare a protective film at a CH ₄ gas concentration at which the Id / Ig and g peak positions show the minimum values. It is considered that the film hardness is high and the abrasion resistance is improved. Vac. Sci. Tech. , A16
(5), 1988, p2941, IEEE TRAN
S. ON MAG. , Vol. 33, no. 5,199
7, p3148, IEEE TRANS. ON MA
G. FIG. , Vol. 33, no. 5, 1997, p310
9. IEICE Technical Report MR92-68, CPM92-145 (1
992-12).

According to these papers, the d peak is the vibration of the bond near carbon at the end of the graphite crystallite, ie, s
The peak attributable to the p3 bond is shown, and the shift of this d peak to the lower wavenumber side means that the asymmetry of the bond and the four-coordinate bond increase, and it is said that the peak is divided into a crystalline phase and an amorphous phase. Have been done. The g peak indicates an in-plane vibration of graphite, that is, a peak due to sp2 bonding. A shift of this g peak to a lower wavenumber side means that the symmetry of the bonding angle is reduced, and a crystallite formed of sp2 bonding Is said to be amorphous-like.

It is said that a decrease in the value of Id / Ig is related to an increase in sp3 binding in the film and a decrease in the size or number of sp2 crystallites. The hydrocarbon film has a structure in which a plurality of microcrystals composed of sp2 bonds are connected by sp3 bonds. When a hydrogen component is added to the structure, a sp3 bond portion grows, and a molecular cluster (cluster) composed of sp2 bonds It is considered that the separation between the _two molecules proceeds, and the excess hydrogen in the film promotes the polymerization by increasing the -CH2- bonds.

The results show that the g peak position is small and Id /
The smaller the Ig, the smaller the sp2-based cluster size and the smaller the sp2 crystallite size or number, which suggests that smaller clusters are more likely to bind to each other, which is desirable for improving the film quality. For this reason, the present inventors
The CH ₄ gas flow rate at which the d / Ig and g peak positions have the minimum values was set as the optimum condition for forming the protective film.

As can be seen from FIG. 2 and FIG.
Means that the concentration of CH ₄ gas in the mixed gas is 2%
Ig and g peak positions showed the minimum values. In contrast,
In Comparative Example 1, the concentration of CH ₄ gas was 4% and Id / Ig was
At 3.3%, the g peak position showed the minimum value. Id / Ig, g peak position, and film density (g / c) in Example 1 and Comparative Example 1 under the optimum conditions obtained in this manner.
m ³ ) were determined and are summarized in Table 1. The thickness of the formed protective film was 5 nm.

[0043]

[Table 1] As shown in Table 1, Example 1 had a higher Id than Comparative Example 1.
/ Ig and g peak positions showed small values. In addition, the density showed a high value. It is considered that the reason why the film density is increased is due to the ion assist effect described above. The results show that the magnetic disk has a high-quality protective film. (Evaluation of Corrosion Resistance) The magnetic disks of Example 1 and Comparative Example 1 were manufactured by adjusting the discharge power of the power supply (discharge voltage × discharge current) to variously change the thickness of the protective film.
The magnetic disk thus obtained was heated at 80 ° C. and 80%
Was left in a constant temperature and humidity chamber for 90 hours, and then immersed in ultrapure water to obtain a solution in which a Co-based corrosive salt as a material for the magnetic film was dissolved. This solution was subjected to inductively coupled plasma mass spectrometry (IC
The amount of Co eluted was measured by analyzing by P-MS) method, and the corrosion resistance was evaluated. FIG. 4 shows the results.

As can be seen from FIG. 4, as the thickness of the protective film becomes thinner, the amount of Co elution increases. However, the magnetic disk of Example 1 has a larger amount of Co elution than that of Comparative Example 1. Showed less. Co in the magnetic film elutes through micropores formed in the protective film. Therefore, Embodiment 1
It was considered that the number of micropores formed was smaller than that of Comparative Example 1 and the density of the protective film was high, indicating that the magnetic disk had high corrosion resistance. (Evaluation of Defects) Protective films were formed by varying the number of times of power supply discharge, and magnetic disks of Example 1 and Comparative Example 1 were produced. The entire surface of the protective film of the magnetic disk thus manufactured was measured and evaluated with a defect detector. This defect detector is used for a magnetic disk rotating at a predetermined rotation speed.
The laser beam is incident obliquely, and the amount of change in reflected light and scattered light due to foreign matter is detected by a detector.
The result is shown in FIG.

As can be seen from FIG. 5, in Example 1, an increase in the number of defects with an increase in the number of discharges was hardly recognized.
When the number of discharges was 21,000, the number of defects was 50 as in the case where the number of discharges was one. On the other hand, Comparative Example 1 showed that the number of defects sharply increased when the number of discharges exceeded 3,000. The number of defects has a correlation with the number of arcs generated during abnormal discharge, and it is considered that the arc causes defects. For this reason, it was considered that the occurrence of an arc was less in Example 1 than in Comparative Example 1, and it was shown that a magnetic disk having no defect could be stably manufactured. (Evaluation of Yield) Glide evaluation and certification evaluation were performed on the magnetic disks of Example 1 and Comparative Example 1 manufactured by changing the number of discharges in the same manner as described above.

Glide evaluation was performed by mounting the magnetic disk on the spindle of a hard disk drive and rotating the magnetic disk so that the magnetic head with a piezo element floated at a height of 10 nm from the surface of the magnetic disk. This is performed by performing a seek operation on the entire surface. If a projection exists on this magnetic disk, the magnetic head collides with the projection, so this impact is detected by the piezo element, and when the output reaches a predetermined value, it is determined that there is a foreign substance, This is a method for evaluating non-defective or defective products based on the presence or absence of foreign matter.

In the certification evaluation, a magnetic head having an MR element is used, and the magnetic head is caused to perform a seek operation on the entire surface of the magnetic disk in the same manner as in the glide evaluation. During the seek operation, a signal is written on the magnetic disk at a predetermined frequency, and the signal is reproduced by the MR element. When reproducing this signal, for example, if a foreign substance attached to the magnetic disk is removed to form a concave portion, the signal will be lost or reduced. In this method, the absence or decrease of the signal is detected by an MR element, and a case where the output is other than a predetermined value is determined as a defect, and a non-defective or defective product is evaluated.

Then, the ratio of magnetic disks determined to be non-defective in the glide evaluation and the certification evaluation with respect to the predetermined number of magnetic disks manufactured was determined, and the evaluation was performed with the yield as the yield. FIG. 6 shows the result.

As can be seen from FIG. 6, in Example 1, the yield was maintained at about 85% regardless of the increase or decrease in the number of discharges, indicating a high yield. On the other hand, Comparative Example 1 shows that the yield is maintained at 70% or more until the number of discharges reaches 6000, but the yield sharply decreases after exceeding 6000 times. Normally, one magnetic disk is manufactured for each discharge, so that Example 1 in which a high yield is maintained even when the number of discharges is increased can improve the productivity of the magnetic disk as compared with Comparative Example 1. It has been shown. (Evaluation of Discharge Voltage) The discharge voltage between the electrodes when the magnetic disks of Example 1 and Comparative Example 1 were manufactured was evaluated by changing the number of discharges in the same manner as described above. FIG. 7 shows the result.

As can be seen from FIG. 7, in Example 1, it was shown that the discharge voltage was almost constant within the range of 440 to 460 V regardless of the increase in the number of discharges. In contrast,
In Comparative Example 1, the discharge voltage tended to increase as the number of discharges increased. Therefore, it was shown that the discharge state between the electrodes in Example 1 was more stable than that in Comparative Example 1. (Evaluation of Film Thickness) The thickness of the protective film was measured for the magnetic disks of Example 1 and Comparative Example 1 while changing the number of discharges in the same manner as described above. The film thickness when the number of discharges is one is 1
Then, the ratio of the film thickness when the number of discharges was changed was determined, and this was regarded as the change rate of the film thickness, and the evaluation was performed. FIG. 8 shows the result.

As can be seen from FIG. 8, in Example 1, the rate of change of the film thickness was around 1, and regardless of the increase in the number of discharges,
It was shown that the film thickness was almost constant. On the other hand, in Comparative Example 1, the rate of change of the film thickness was decreased, and the film thickness tended to be reduced as the number of discharges increased. It is considered that the reason why the film thickness is reduced in Comparative Example 1 is that the non-erosion region is expanded and the region where the target is sputtered (erosion region) is narrowed due to the formation of the CH film on the target surface due to the increase in the number of discharges. . Therefore, it was shown that the quality of the magnetic disk manufactured in Example 1 was more stable than that of Comparative Example 1.

The above embodiments can be embodied with the following modifications. -Only one electrode 13 is provided in the apparatus main body 11 of the sputtering apparatus, and a positive or negative voltage is applied to the electrode 13 by an AC power supply to change the electrode 13 to a cathode or an anode at a predetermined frequency. By making the chamber wall and the shield plate function as an anode or a cathode, a protective film may be formed only on one surface of the substrate 15. Even in the case of such a configuration, it is possible to easily produce an extremely thin protective film having excellent durability and corrosion resistance, and it is possible to improve the production yield.

The substrate 15 of each embodiment is the main body 11 of the apparatus.
The structure is not limited to being fixed between the two electrodes 13, and may be configured to move in the longitudinal direction while being disposed at the center between the two electrodes 13. With this configuration, the substrate 15 can be continuously loaded into the apparatus main body 11.

As shown in FIG. 9, two pairs of counter electrodes are arranged in parallel, and the electrodes 13 of each counter electrode are inverted so as to have the same polarity, and a pair of electrodes arranged in parallel in one plane. 13 may be configured to be inverted so as to have mutually different polarities. Then, while moving the substrate 15 in a direction extending in parallel with the direction in which the electrodes 13 are arranged, the substrate 1
The protective film may be formed only on one surface of the substrate 15 by applying a voltage only to the electrode 13 on one of the surfaces 5. Alternatively, a protective film may be formed on both surfaces of the substrate 15 by applying a voltage to all the electrodes 13. With such a configuration, a protective film can be easily formed on one side and both sides of the substrate 15 as desired.

The waveform of the applied voltage may be any of a sine wave, a square pulse wave, and a pulse wave with asymmetric polarity. Thus, even if the voltage waveform is changed, the polarity of the electrode 13 can be inverted.

Further, the technical ideas that can be grasped from this embodiment will be described below. The magnet according to any one of claims 1 to 4, wherein an AC power supply whose output frequency is adjustable is used as a power supply for applying a voltage to the electrode, and the polarity of the electrode is inverted at a predetermined frequency. Disc manufacturing method.

With this configuration, the polarity of the electrode can be easily inverted at a predetermined frequency. A DC power supply is used as a power supply for applying a voltage to the electrode, and a polarity converter that changes the output polarity from the DC power supply at predetermined intervals is connected between the DC power supply and the electrode, and the polarity of the electrode is changed. 5. The method for manufacturing a magnetic disk according to claim 1, wherein the magnetic disk is inverted at a predetermined frequency.

With this configuration, the polarity of the electrode can be easily inverted at a predetermined frequency.

[0059]

As described above in detail, according to the present invention, the following effects can be obtained. According to the method of manufacturing a magnetic disk according to the first aspect of the present invention, it is possible to easily manufacture a non-conductive film which is extremely thin and has excellent durability and corrosion resistance, thereby improving the manufacturing yield. be able to.

According to the method of manufacturing a magnetic disk according to the second aspect of the present invention, in addition to the effects of the first aspect of the present invention, a non-conductive film which is extremely thin and has excellent durability and corrosion resistance is provided. It can be easily manufactured on both sides and one side of the substrate.

According to the method of manufacturing a magnetic disk of the invention described in claim 3, in addition to the effect of the invention described in claim 2, a dense non-conductive film having few defects such as fine holes on the surface is formed on the substrate. Can be formed on both sides of the film, and the quality of the film can be improved easily and at low cost.

According to the method of manufacturing a magnetic disk of the invention described in claim 4, in addition to the effect of the invention described in claim 2, a dense non-conductive film having few defects such as fine holes on the surface is formed on the substrate. Can be simultaneously formed on both surfaces, and the film quality can be improved.

According to the method of manufacturing a magnetic disk of the invention described in claim 5, in addition to the effects of the invention described in any one of claims 1 to 4, the discharge between the electrodes can be stably performed. Can be.

According to the sputtering apparatus of the sixth aspect of the present invention, it is possible to easily produce a magnetic disk having an extremely thin non-conductive film having excellent durability and corrosion resistance while improving the production yield. Can be manufactured.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a sputtering apparatus.

FIG. 2 is a graph showing the relationship between Id / Ig and methane gas concentration.

FIG. 3 is a graph showing a relationship between a g peak position and a methane gas concentration.

FIG. 4 is a graph showing the relationship between the amount of Co eluted and the thickness of a protective film.

FIG. 5 is a graph showing the relationship between the number of defects of a protective film and the number of discharges between electrodes.

FIG. 6 is a graph showing the relationship between yield and the number of discharges between electrodes.

FIG. 7 is a graph showing a relationship between a discharge voltage between electrodes and the number of discharges between electrodes.

FIG. 8 is a graph showing the relationship between the rate of change in film thickness and the number of discharges between electrodes.

FIG. 9 is a conceptual diagram illustrating another embodiment of a sputtering apparatus.

[Explanation of symbols]

 13 ... electrode, 15 ... substrate.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takeshi Nishii 3-5-11, Doshumachi, Chuo-ku, Osaka-shi, Japan Nippon Sheet Glass Co., Ltd. (72) Inventor Katsuhisa 3-chome, Doshucho, Chuo-ku, Osaka-shi, Osaka No. 5-11 Nippon Sheet Glass Co., Ltd. F term (reference) 4K029 AA09 BA55 BB02 BD11 CA06 DC02 DC32 5D112 AA07 FA04 FB21

Claims (6)

[Claims] 1. A method for manufacturing a magnetic disk, comprising: forming at least a magnetic film on a surface of a substrate, and then forming a non-conductive film on the magnetic film by sputtering using a sputtering apparatus, wherein the polarity is reversed. A non-conductive film is formed by using a sputtering apparatus provided with an electrode for reversing the polarity as described above. 2. At least one pair of counter electrodes comprising a pair of electrodes facing each other is disposed in the sputtering apparatus, a substrate is disposed between the pair of electrodes, and the polarities of the pair of electrodes constituting the counter electrodes are provided. 2. The method according to claim 1, wherein the non-conductive film is formed by changing the directions of the non-conductive films. 3. The two electrodes have different polarities so that if one of the counter electrodes is an anode, the other electrode is a cathode, and if one electrode is a cathode, the other electrode is an anode. 3. The method for manufacturing a magnetic disk according to claim 2, wherein 4. If both electrodes of the counter electrode are anodes, the other electrode also serves as an anode, and if one electrode is a cathode, the other electrode also serves as a cathode so that both electrodes have the same polarity. 3. The method for manufacturing a magnetic disk according to claim 2, wherein 5. The method according to claim 1, wherein the polarity of the electrodes is inverted at a frequency of 1 to 100 kHz. 6. A substrate having at least a magnetic film on a surface of the substrate,
A sputtering apparatus for forming a non-conductive film of a magnetic disk, in which a non-conductive film is formed on the magnetic film, by sputtering, comprising: an electrode for reversing the polarity so that the polarity is reversed. Characteristic sputtering equipment.