JP2009155694A - Film deposition apparatus, film deposition method, manufacturing method of magnetic recording medium, and manufacturing method of magnetic recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film deposition apparatus and a film deposition method capable of reliably eliminating droplets with a relatively simple constitution, and a manufacturing method of a magnetic recording medium, and a manufacturing method of a magnetic recording device. <P>SOLUTION: A cathode electrode 21 consisting of graphite is arranged on the inner side of a cylindrical anode electrode 24 consisting of graphite. The power is supplied from a power source 26 between the anode electrode 24 and the cathode electrode 21, and plasma containing carbon ions is generated around the cathode electrode 21 by generating the arc discharge. The plasma goes out via an aperture formed in the anode electrode 24, its advancing direction is bent by the magnetic field by a coil 25, and the plasma is conveyed to a substrate. Carbon ions in the plasma are deposited on a surface of the substrate to form a DLC membrane. On the other hand, droplets generated by the arc discharge are hardly affected by the magnetic field, and scattered in the direction independent from the plasma conveying direction to avoid deposition on the DLC membrane. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a film forming apparatus and a film forming method suitable for forming a protective film for protecting the surface of a magnetic recording medium used in a magnetic recording apparatus and the tip of a magnetic head, a method for manufacturing a magnetic recording medium, and a magnetic recording apparatus. It relates to a manufacturing method.

  In recent years, magnetic recording devices (hard disk drives) have come to be used not only for computers but also for video recording devices such as hard disk video recorders, portable music playback devices, and the like.

  In a magnetic recording apparatus, data is recorded by magnetizing a recording layer of a disk-shaped magnetic recording medium (magnetic disk) rotating at high speed with a magnetic head. A protective film is provided on the recording layer in order to protect the recording layer from physical and chemical damage. Usually, a diamond-like carbon film (hereinafter referred to as “DLC film”) formed by sputtering or CVD (Chemical Vapor Deposition) is used as a protective film of a magnetic recording medium.

  In recent years, further improvement in the recording density of magnetic recording media has been desired. For this purpose, it is essential to reduce the distance (magnetic spacing) between the recording layer of the magnetic recording medium and the magnetic head, and a further reduction in the thickness of the protective film is required. Currently, a DLC film used as a protective film on the surface of a magnetic recording medium is formed by sputtering or CVD as described above. However, a DLC film formed by sputtering or CVD is considered to have insufficient hardness when thinned, and a film forming method capable of forming a DLC film with higher hardness is desired.

  Therefore, in recent years, it has been proposed to form a DLC film on the surface of a magnetic recording medium using an FCA (Filtered Cathodic Arc) method using an arc as a plasma source. When a DLC film is formed by the FCA method, plasma containing carbon ions is generated by arc discharge using a cathode electrode (target) made of carbon, and the carbon ions are attached to the surface of the magnetic recording medium.

In the FCA method, since a DLC film is formed by depositing carbon ions, a high-hardness DLC film rich in sp ³ bonds and free of C—H bonds that cause a decrease in hardness can be obtained. In addition, the FCA method has better DLC film coverage than the CVD method, and even if the thickness of the DLC film is, for example, 3.5 nm or less, the reliability as a protective film is not impaired. Hereinafter, an apparatus for forming a film by the FCA method is referred to as an FCA film forming apparatus.

  By the way, in order to stably perform the DLC film formation process by the FCA method, it is necessary to precisely control the amount of carbon evaporation at the discharge point. However, it is virtually impossible to control the amount of carbon evaporation at the discharge point. The surface temperature of the cathode electrode suddenly rises due to arc discharge, and the surface of the cathode electrode is partially destroyed. Graphite particles) are generated. Such particles are called droplets. When the droplets adhere to the surface of the magnetic recording medium, the magnetic head and the droplet collide with each other to cause a head crash, or the protective film is destroyed and the recording layer is damaged.

  A general FCA apparatus is provided with a magnetic deflection type mass analyzer as described in, for example, Patent Document 1, and the mass analyzer separates plasma containing ions of a film forming material from droplets. Then, only the plasma is transferred onto the substrate to form a film.

In addition, there exist patent document 2 and nonpatent literature 1 as a prior art considered to be related to this invention. Patent Document 2 describes a thin film forming apparatus (FAC film forming apparatus) having a structure in which a cylindrical anode electrode is disposed around a rod-shaped cathode electrode. In this thin film forming apparatus, droplets generated by arc discharge are captured by the anode electrode, and plasma generated by arc discharge is moved in the central axis direction of the anode electrode to form a thin film on the substrate. Non-Patent Document 1 describes that the optical gap of the film is reduced when graphite particles are locally present in the DLC film.
JP 2002-8893 A Japanese Patent No. 2857743 KBK Teo et al. "Effect of graphitic inclusions on the optical gap of tetrahedral amorphous carbon films" JOURNAL OF APPLIED PHYSICS vol.89, No.7,3706-3710, APRIL 2001

  In a conventional general FCA apparatus, plasma and droplets are separated using a mass analyzer as described above. However, when the DLC film is formed, the droplets often reach the substrate surface due to reflection on the inner wall of the apparatus, and it is difficult to stably form the DLC film without the droplets. Although it is possible to dispose the droplets more completely by arranging the mass analyzers in multiple stages, in this case, there arises a problem that the apparatus becomes complicated and large, and the film forming speed is also reduced.

  In the thin film forming apparatus disclosed in Patent Document 2, since the anode electrode is only formed in a cylindrical shape, there is nothing to block the droplet protruding from the cathode electrode toward the substrate, and the anode electrode is formed on the substrate. It is considered that droplets adhere to the film. In addition, the thin film forming apparatus disclosed in Patent Document 2 is intended to attach and capture droplets generated by arc discharge on the anode electrode, and is therefore not suitable for forming a DLC film. That is, since the droplet generated when the DLC film is formed is not a droplet, it is reflected by the anode electrode, and it is difficult to capture the droplet by the anode electrode.

  An object of the present invention is to provide a film forming apparatus and a film forming method, a magnetic recording medium manufacturing method, and a magnetic recording apparatus manufacturing method capable of more reliably eliminating droplets with a relatively simple configuration. .

  According to one aspect of the present invention, a base material placement portion on which a base material is placed, a cylindrical anode electrode that is placed away from the base material placement portion and has an opening on a peripheral surface, and A cathode electrode disposed inside the anode electrode, a power source for generating arc discharge by applying a voltage between the anode electrode and the cathode electrode, and generating plasma around the cathode electrode; and the anode electrode A film forming apparatus is provided that includes a magnetic field generating unit that bends the traveling direction of the plasma that has exited the anode electrode through the opening of the anode by a magnetic field and conveys the plasma toward the substrate placement unit. .

  According to another aspect of the present invention, in a film forming method for forming a film by depositing ions contained in plasma on a surface of a base material, a cylindrical anode having an opening on a peripheral surface A step of arranging a cathode electrode inside the electrode, supplying electric power between the anode electrode and the cathode electrode to generate an arc discharge, and generating plasma around the cathode electrode; and opening the anode electrode And a step of bending the direction of travel of the plasma emitted from the part by a magnetic field and transporting the plasma to the substrate side.

  In the present invention, a voltage is applied between an anode electrode having an opening on the peripheral surface and a cathode electrode disposed inside the anode electrode to generate arc discharge, and plasma is generated around the cathode electrode. Is generated. This plasma contains ions of the material constituting the cathode electrode. For example, when the cathode electrode is made of carbon, carbon ions are contained in the plasma.

  The plasma generated around the cathode electrode passes through the opening provided in the anode electrode, exits the anode electrode, is bent in the traveling direction by the magnetic field generated by the magnetic field generation unit, and is transported to the substrate. . And the ion in plasma accumulates on the surface of a base material, and a film | membrane is formed. For example, when carbon ions are contained in the plasma, a DLC film is formed on the surface of the substrate.

  On the other hand, the droplets generated by the arc discharge have no charge or only a very small charge compared to the mass, so that the traveling direction is not bent by the magnetic field even when going out from the opening of the anode electrode. (Or the traveling direction is bent only a little), so that it is separated from the plasma and scattered in a direction unrelated to the traveling direction of the plasma. Thereby, a droplet does not reach a base material and it is avoided that a droplet adheres to the film | membrane formed on the surface of a base material.

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

  FIG. 1 is a schematic diagram showing a configuration of a film forming apparatus according to an embodiment of the present invention. 2A and 2B are cross-sectional views showing the plasma generation source, and FIG. 3 is an enlarged view of the cathode electrode and anode electrode portions of FIG. 2A. FIG. 2B shows a cross section taken along the line II in FIG. In this embodiment, a case where a DLC film is formed on the surface of a substrate (magnetic recording medium) is described.

  As shown in FIG. 1, the film forming apparatus of the present embodiment includes a film forming chamber 11 in which a substrate (magnetic recording medium) 10 is disposed, a plasma chamber 12 in which a plasma generation source 20 is disposed, and film formation thereof. It is comprised by the connection part 13 which connects the chamber 11 and the plasma chamber 12. FIG. In the present embodiment, at least one of the film forming chamber 11 and the plasma chamber 12 is connected to a vacuum apparatus, and the inside of the film forming chamber 11 and the plasma chamber 12 is maintained in a vacuum.

  The plasma containing the film forming material (carbon ions) generated by the plasma generation source 20 is transferred from the plasma chamber 12 through the connecting portion 13 to the film forming chamber 11 and is placed in the film forming chamber 11. Carbon ions are deposited on the surface of the film to form a DLC film.

  As shown in FIGS. 2A and 2B, the plasma generation source 20 includes a cathode electrode 21, an insulating layer 22, a trigger electrode 23, an anode electrode 24, and a coil 25. The cathode electrode 21 is formed in a rod shape from graphite (carbon), and the central axis thereof is disposed toward the film forming chamber 11. In the present embodiment, a part of the cathode electrode 21 on the film forming chamber 11 side is referred to as a front end part, and a part on the opposite side is referred to as a rear end part. The diameter of the cathode electrode 21 is 15 mm, for example.

  The insulating layer 22 is formed so as to cover the rear end portion of the cathode electrode 21. The trigger electrode 23 is formed so as to cover the periphery of the rear end side of the cathode electrode 21 through the insulating layer 22. The trigger electrode 23 is also made of graphite (carbon).

  The anode electrode 24 is formed in a cylindrical shape whose inner diameter is larger than the outer diameter of the trigger electrode 23, and is arranged concentrically with the cathode electrode 21 as shown in FIG. The anode electrode 24 is also made of graphite (carbon). The peripheral surface (cylindrical portion) of the anode electrode 24 is meshed, and an opening 24a through which plasma passes is provided as shown in FIG. Further, the end of the anode electrode 24 on the front end side (deposition chamber side) is closed by a shielding wall 24b, and the drop red generated by the arc discharge directly jumps out into the deposition chamber 11 by the shielding wall 24b. I am trying not to. The diameter (outer diameter) of the anode electrode 24 is 40 mm, for example.

  As shown in FIG. 2A, a direct current voltage is applied between the cathode electrode 21 and the anode electrode 24 from the first power supply 26. A high voltage pulse (trigger voltage) is applied between the trigger electrode 24 and the anode electrode 24 from the second power source 27.

  As shown in FIG. 2B, a plurality of coils 25 are arranged radially around the anode electrode 24 around the anode electrode 24. DC power is supplied to these coils 25 from a power source (not shown), and the plasma that has flowed out of the anode electrode 24 through the opening 24a of the anode electrode 24 is conveyed in the direction toward the film forming chamber 11 by Lorentz force. In the present embodiment, it is assumed that the arc discharge current and the current supplied to the coil 25 can be individually adjusted.

  Hereinafter, the operation of the film forming apparatus of this embodiment will be described.

First, the vacuum apparatus is operated to depressurize the film forming chamber 11 and the plasma chamber 12, and the pressure in the film forming chamber 11 and the plasma chamber 12 is set to 5 × 10 ⁻³ Pa, for example. Next, for example, a wave is applied from the second power source 27 between the trigger electrode 23 and the cathode electrode 24 with a DC voltage of, for example, 150 V applied from the first power source 26 between the cathode electrode 21 and the anode electrode 24. A high voltage pulse having a high value of 5 kV is applied for a short time.

  Thereby, a vacuum arc discharge is started between the cathode electrode 21 and the anode electrode 24. Due to this vacuum arc discharge, carbon constituting the cathode electrode 21 is evaporated, and plasma 31 containing carbon ions is generated around the cathode electrode 21 as schematically shown in FIG. The plasma 31 moves in a direction away from the cathode electrode 21 and exits to the outside of the anode electrode 24 through the opening 24 a of the anode electrode 24. The plasma 31 emitted to the outside of the anode electrode 24 is transported toward the film forming chamber 11 by the magnetic field generated from the coil 25. The arrows in FIG. 3 indicate the moving direction of the plasma 31.

  On the other hand, the droplet generated by the arc discharge also goes out of the anode electrode 24 through the opening 24 a of the anode electrode 24. However, since the droplets have no charge or only a small charge compared to the mass, the traveling direction hardly changes in the magnetic field of the coil 25 and scatters in a direction unrelated to the film forming chamber 11. And finally, it is captured by the inner wall surface (droplet supplement member) of the plasma chamber 12.

  By appropriately adjusting the intensity of the magnetic field generated by the coil 25, the trajectory of plasma particles (carbon ions) necessary for film formation is greatly bent and conveyed to the film formation chamber 11, and the droplets are stored in the plasma chamber 12. It becomes possible to capture on the wall.

  Further, the droplets discharged from the cathode electrode 21 toward the film forming chamber 11 along with the arc discharge are shielded by the shielding wall 24b of the anode electrode 24 and are prevented from moving toward the film forming chamber 11.

  In this way, plasma containing no droplets is transferred to the film forming chamber 11, and a high-hardness DLC film containing almost no droplets is formed on the surface of the substrate 10 placed in the film forming chamber 11. The

  According to the present embodiment, a high-hardness DLC film without droplets can be stably formed on the surface of the substrate (magnetic recording medium). Thereby, the reliability of the magnetic recording medium and the magnetic recording apparatus using the magnetic recording medium can be greatly improved. Further, the film forming apparatus according to the present embodiment has a relatively simple structure, and avoids complication, enlargement, and cost increase of the apparatus.

  In the present embodiment, the plasma generated by the plasma generation source 20 is directly transferred to the film formation chamber 11, but is realized by a magnetic field or a barrier between the plasma generation source 20 and the film formation chamber 11. A filter may be arranged to remove the droplets more reliably.

  In the present embodiment, the trigger electrode 23 and the anode electrode 24 are made of graphite (carbon). However, the trigger electrode 23 or the anode electrode 24 may be made of a material other than graphite. However, from the viewpoint of increasing the purity of the DLC film, it is preferable that both the trigger electrode 23 and the anode electrode 24 are formed of graphite (carbon) as described above.

  Further, in the present embodiment, plasma is transferred to the film forming chamber 11 by a magnetic field generated from the coil 25, but a permanent magnet may be used instead of the coil 25.

  Hereinafter, the results of actually forming a DLC film using the apparatus of the present embodiment having the structure shown in FIGS. 1 and 2 and examining the presence or absence of droplets and the hardness of the DLC film will be described.

  According to Teo et al. (Non-Patent Document 1), when graphite particles are locally present in the DLC film, the optical gap of the DLC film decreases. This means that it is possible to determine whether or not droplets are attached to the DLC film by measuring the size of the optical gap.

Therefore, as an example, a DLC film having a thickness of 30 nm is formed on an MgF ₂ substrate using the film forming apparatus according to the present embodiment, and the visible absorption spectrum of the DLC film is measured by a spectrometer (U3200 Spectroscope manufactured by Hitachi, Ltd.). Measured by the transmission method with a photometer), the absorbance count (α (E)) and the light energy (E) are Tauc plot ((α (E) E) 1/2 vs. E), and the slope and intercept of the plot From these, the optical gap was calculated. As a result, the optical gap of the DLC film formed by the film forming apparatus according to the present embodiment was 3.65 eV. The film forming conditions are as shown in Table 1 below.

また、本実施形態に係る成膜装置を使用して、Ｓｉ基板上にＤＬＣ膜を３０ｎｍの厚さに形成し、そのＤＬＣ膜の硬度をHysitron社製のTriboscopeにより測定した。その結果、ＤＬＣ膜の硬度は４７ＧＰａであった。

In addition, a DLC film having a thickness of 30 nm was formed on a Si substrate using the film forming apparatus according to the present embodiment, and the hardness of the DLC film was measured with a Triboscope manufactured by Hysitron. As a result, the hardness of the DLC film was 47 GPa.

On the other hand, as a comparative example, a DLC film was formed on an MgF ₂ substrate and an Si substrate by a general FCVA (Filtered Cathodic Vacuum Arc) method, and an optical gap and hardness were measured. However, the pressure in the film forming chamber was 5 × 10 ⁻³ Pa, the discharge voltage was 120 V, and the discharge current was 60 A. As a result, the optical gap of the DLC film of the comparative example was 2.8 eV, and the hardness was 49 GPa.

  From Teo et al. (Non-Patent Document 1), it can be seen that when the optical gap is 2.8 eV, the number of droplets is relatively large, and when the optical gap is 3.6 eV, the number of droplets is extremely small. From the measurement results of the optical gap and hardness of these examples and comparative examples, the DLC film formed by the film forming apparatus according to this embodiment has a sufficiently high hardness and includes droplets (graphite particles). Not confirmed.

  In the above-described embodiment, the case where the present invention is applied to the formation of the DLC film (protective film) on the surface of the magnetic recording medium has been described. However, the present invention is limited to the formation of the protective film of the magnetic recording medium. Of course, it is not a thing. For example, the present invention may be applied to the formation of a protective film (DLC film) for a magnetic head, or may be applied to the formation of a film other than a DLC film.

FIG. 1 is a schematic diagram showing a configuration of a film forming apparatus according to an embodiment of the present invention. 2A and 2B are cross-sectional views showing a plasma generation source of the film forming apparatus according to the embodiment. FIG. 3 is an enlarged view of the cathode electrode and anode electrode portions of FIG.

Explanation of symbols

10 ... Substrate (magnetic recording medium),
11 ... deposition chamber,
12 ... Plasma chamber
20 ... Plasma generation source,
21 ... cathode electrode,
22: Insulating layer,
23 ... trigger electrode,
24 ... Anode electrode,
25 ... Coil,
26. First power source,
27: Second power source.

Claims (8)

A base material placement part on which the base material is placed;
A cylindrical anode electrode disposed apart from the base material placement portion and provided with an opening on the peripheral surface;
A cathode electrode disposed inside the anode electrode;
A voltage is applied between the anode electrode and the cathode electrode to generate an arc discharge, and a power source that generates plasma around the cathode electrode;
A magnetic field generating unit configured to bend the traveling direction of the plasma emitted outside the anode electrode through the opening of the anode electrode by a magnetic field and transport the plasma toward the base material arrangement unit. A film forming apparatus.   2. The film formation according to claim 1, wherein the anode electrode is disposed with a central axis thereof facing the substrate placement portion, and an end portion of the anode electrode on the substrate placement portion side is closed. apparatus.   The film forming apparatus according to claim 1, wherein the magnetic field generation unit includes a plurality of coils arranged radially around the anode electrode.   The film forming apparatus according to claim 1, wherein the cathode electrode is made of carbon. In a film forming method for forming a film by depositing ions contained in plasma on a surface of a substrate,
A cathode electrode is arranged inside a cylindrical anode electrode having an opening in the peripheral surface, and electric power is supplied between the anode electrode and the cathode electrode to generate an arc discharge. A step of generating plasma,
And a step of bending the traveling direction of the plasma emitted from the opening of the anode electrode by a magnetic field and transporting the plasma to the substrate side.   6. The film forming method according to claim 5, wherein graphite is used as the cathode electrode, and a diamond-like carbon film is formed on the surface of the substrate. Electric power is supplied between a cylindrical anode electrode having an opening around the cathode electrode and a cathode electrode arranged inside the anode electrode to generate arc discharge, and plasma is generated around the cathode electrode. ,
A method for producing a magnetic recording medium, comprising: bending a traveling direction of the plasma emitted from the opening of the anode electrode by a magnetic field and depositing ions contained in the plasma on the magnetic recording medium. Electric power is supplied between a cylindrical anode electrode having an opening around the cathode electrode and a cathode electrode arranged inside the anode electrode to generate arc discharge, and plasma is generated around the cathode electrode. ,
A method for manufacturing a magnetic recording apparatus, comprising: a step of bending a plasma traveling direction from an opening of the anode electrode by a magnetic field and depositing ions contained in the plasma on a magnetic recording medium.

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