JP2014025117A - Plasma cvd apparatus and method of manufacturing magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a thickness of a film to be deposited on a substrate to have a film deposited, with excellent uniformity.SOLUTION: A plasma CVD apparatus includes: a chamber 102; an anode 104; a cathode 103; a holding part for holding a substrate 1 to have a film deposited; an inner shield 108 provided so as to cover spaces between the substrate to have a film deposited and the anode and the cathode respectively; a magnet 109 disposed on the outer side of the inner shield and arranged so as to surround the inner shield; a first DC power source 107 electrically connected to the anode; an AC power source 105 electrically connected to the cathode; a second DC power source 112 electrically connected to the substrate to have a film deposited, which is held by the holding part; a gas supply mechanism for supplying a raw material gas into the chamber; and an exhaust mechanism for exhausting the inside of the chamber. A distance between a plane 109c which is parallel to the surface of the substrate to have a film deposited and includes an end 109b on the side of the substrate to have a film formed of the magnet, and the surface of the substrate to have a film deposited is 15-100 mm.

Description

  The present invention relates to a plasma CVD apparatus and a method for manufacturing a magnetic recording medium.

  FIG. 5 is a cross-sectional view schematically showing a plasma CVD apparatus. This plasma CVD apparatus is an apparatus for forming a thin film on both surfaces of a film formation substrate 101, and is configured symmetrically with respect to the film formation substrate 101, but only the left side is shown in FIG.

  The plasma CVD apparatus has a chamber, and a filamentary cathode electrode 103 made of, for example, tantalum is formed in the chamber 102. Both ends of the cathode electrode 103 are electrically connected to the cathode power source 105, and the cathode power source 105 is electrically connected to the ground 106. An anode electrode 104 having a funnel shape is disposed so as to surround the periphery of the cathode electrode 103. The anode 104 electrode is electrically connected to the positive potential side of the DC (direct current) power source 107, and the negative potential side of the DC power source 107 is electrically connected to the ground.

  A deposition target substrate 101 is disposed in the chamber 102, and the deposition target substrate 101 is disposed to face the cathode electrode 103 and the anode electrode 104. The deposition target substrate 101 is electrically connected to the negative potential side of a bias power source (DC power source) 112 as an ion acceleration power source, and the positive potential side of the DC power source 112 is electrically connected to the ground 106.

  An inner shield 108 is disposed in the chamber 102 so as to cover the space between the cathode electrode 103 and the anode electrode 104 and the deposition target substrate 101.

  In addition, the plasma CVD apparatus has an evacuation mechanism (not shown) for evacuating the chamber 102. Further, the plasma CVD apparatus has a gas supply mechanism (not shown) for supplying a film forming material gas into the chamber (see, for example, Patent Document 1).

  There is a demand for controlling the thickness of a film deposited on the deposition target substrate 101 with the plasma processing apparatus with good uniformity.

Patent 3930181 (FIG. 1)

  An object of one embodiment of the present invention is to provide a plasma CVD apparatus or a method for manufacturing a magnetic recording medium that can control the thickness of a film formed over a deposition target substrate with high uniformity.

Hereinafter, various aspects of the present invention will be described.
(1) a chamber;
An anode disposed in the chamber;
A cathode disposed within the chamber;
A holding unit arranged in the chamber and holding a deposition target substrate arranged to face the cathode and the anode;
An inner shield disposed in the chamber and provided so as to cover a space between the deposition target substrate held by the holding unit and each of the anode and the cathode;
A magnet disposed in the chamber, disposed outside the inner shield, and disposed so as to surround the inner shield;
A first DC power supply electrically connected to the anode;
An AC power source electrically connected to the cathode;
A second DC power source electrically connected to the film formation substrate held by the holding unit;
A gas supply mechanism for supplying a source gas into the chamber;
An exhaust mechanism for exhausting the chamber;
Comprising
The distance between the plane parallel to the surface of the film formation substrate and including the end of the magnet on the film formation substrate side and the surface of the film formation substrate is 15 to 100 mm (preferably 20 to 50 mm). There is a plasma CVD apparatus.

(2) In (1) above,
The inner shield is surrounded by 2n magnets,
Each of the 2n magnets has one of the north and south poles facing the inner shield, and the adjacent magnets have opposite magnetic poles facing the inner shield. CVD equipment.
However, n is an integer of 2-12.

(3) In (2) above,
A plasma CVD apparatus characterized in that the magnetic field around the deposition substrate is within a range of ± 0.1 G to ± 50 G (preferably ± 1 G to ± 40 G).

(4) In (1) above,
The inner shield is surrounded by one magnet,
The plasma CVD apparatus according to claim 1, wherein the one magnet has one of an N pole and an S pole facing the cathode side and the other of the N pole and the S pole facing the deposition target substrate side.

(5) In any one of (1) to (4) above,
An outer shield disposed within the chamber and disposed outside the inner shield;
The plasma CVD apparatus, wherein the magnet is located outside the outer shield.

(6) In the method for manufacturing a magnetic recording medium using the plasma CVD apparatus according to any one of (1) to (5),
Holding the film formation substrate on which at least the magnetic layer is formed on the nonmagnetic substrate in the holding unit,
The source gas is brought into a plasma state by discharge between the cathode and the anode in the chamber, and the plasma is accelerated and collided with the surface of the film formation substrate held in the holding portion, so that carbon is a main component. A method for producing a magnetic recording medium, comprising forming a protective layer.

(7) In the method of manufacturing a magnetic recording medium, a protective layer mainly composed of carbon is formed after forming at least a magnetic layer on a nonmagnetic substrate.
A method for producing a magnetic recording medium, wherein the protective layer is formed using the plasma CVD apparatus according to any one of (1) to (5) above.

  According to one embodiment of the present invention, a plasma CVD apparatus or a method for manufacturing a magnetic recording medium that can control the thickness of a film formed over a deposition target substrate with high uniformity can be provided.

1 is a cross-sectional view schematically showing a plasma CVD apparatus according to Embodiment 1. FIG. 6 is a cross-sectional view schematically showing a plasma CVD apparatus according to a second embodiment. FIG. (A) is a photograph of the DLC film 10 formed on the film formation substrate 1 using the plasma processing apparatus shown in FIG. 2, and (B) is a DLC film formed on the film formation substrate 1 shown in (A). 2 is a cross-sectional view schematically showing the film thickness of a film 10. FIG. 2A is a photograph of the DLC film 11 formed on the film formation substrate 1 using an apparatus obtained by removing the magnet 119 from the plasma CVD apparatus shown in FIG. 2, and FIG. 2B is a film formation substrate 1 shown in FIG. It is sectional drawing which shows typically the film thickness of the DLC film 11 formed into a film on it. It is sectional drawing which shows a plasma CVD apparatus typically.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below.

[Embodiment 1]
<Plasma CVD equipment>
FIG. 1 is a cross-sectional view schematically illustrating a plasma CVD apparatus according to one embodiment of the present invention. This plasma CVD apparatus has a symmetrical structure with respect to a film formation substrate (for example, a disk substrate) 1 and can form films on both surfaces of the film formation substrate 1 simultaneously. Only shows.

  The plasma CVD apparatus has a chamber 102, and a filamentary cathode electrode (cathode filament) 103 made of, for example, tantalum is formed in the chamber 102. Both ends of the cathode filament 103 are electrically connected to a cathode power source (AC power source) 105 located outside the chamber 102, and the cathode power source 105 is disposed in an insulated state with respect to the chamber 102.

  The cathode power source 105 is controlled by a control unit (not shown). Thereby, the voltage applied to the cathode filament 103 is controlled. As the cathode power source 105, for example, a power source of 0 to 50 V and 10 to 50 A (ampere) can be used. One end of the cathode power source 105 is electrically connected to the ground 106.

  An anode electrode (anode cone) 104 having a funnel shape is disposed in the chamber 102 so as to surround each cathode filament 103, and the anode cone 104 is shaped like a speaker.

  The anode cone 104 is electrically connected to an anode power source (DC (direct current) power source) 107, and the DC power source 107 is disposed in an insulated state with respect to the chamber 102. The positive potential side of the DC power source 107 is electrically connected to the anode cone 104, and the negative potential side of the DC power source 107 is electrically connected to the ground 106.

  The DC power source 107 is controlled by the control unit. Thereby, the voltage applied to the anode cone 104 is controlled. As the DC power source 107, for example, a power source of 0 to 500 V and 0 to 7.5 A (ampere) can be used.

  A deposition substrate 1 is disposed in the chamber 102, and the deposition substrate 1 is disposed so as to face the cathode filament 103 and the anode cone 104. Specifically, the cathode filament 103 is surrounded in the vicinity of the central portion of the inner peripheral surface of the anode cone 104, and the anode cone 104 is arranged with the maximum inner diameter side facing the deposition target substrate 1.

  The deposition target substrate 1 is sequentially supplied to the positions shown by a holder (holding unit) not shown and a transfer device (handling robot or rotary index table) not shown.

  The deposition target substrate 1 is electrically connected to a bias power source (DC power source, DC power source) 112 as a power source for accelerating ions, and the DC power source 112 is arranged in an insulated state with respect to the chamber 102. . The negative potential side of the DC power source 112 is electrically connected to the deposition target substrate 1, and the positive potential side of the DC power source 112 is electrically connected to the ground 106.

  The DC power source 112 is controlled by the control unit. Thereby, the voltage applied to the deposition target substrate 1 is controlled. As the DC power source 112, for example, a power source of 0 to 1500 V and 0 to 100 mA (milliampere) can be used.

  An inner shield 108 made of a conductor is provided on the deposition substrate 1 side of the anode cone 104, and the inner shield 108 forms a space between the cathode filament 103 and the anode cone 104 and the deposition substrate 1. It is formed to cover. The inner shield 108 has a float potential and is disposed in an insulated state with respect to the chamber 102. The inner shield 108 has a cylindrical shape or a polygonal shape.

  A film thickness correction plate 118 is provided at the end of the inner shield 108 on the film formation substrate 1 side. The film thickness correction plate 118 is electrically connected to the inner shield 108 and has a float potential. The film thickness correction plate 118 controls the thickness of the film formed on the outer peripheral portion of the deposition target substrate 1.

  An outer shield 90 made of a conductor or an insulator is disposed outside the inner shield 108 so as to cover the inner shield 108, and the outer shield 90 has a cylindrical shape or a polygonal shape. The outer shield 90 is electrically connected to a float potential or a ground potential. The outer shield 90 has a role of preventing discharge between the chamber 102 and the inner shield 108.

  One magnet (for example, a neodymium magnet) 109 is disposed inside the chamber 102 and outside the outer shield 90, and the magnet 109 is disposed so as to surround the inner shield 108. The magnet 109 is disposed closer to the film formation substrate 1 than the cathode filament 103. Specifically, a plane 109 c that is parallel to the surface of the film formation substrate 1 (the surface on the magnet 109 side) and includes the end 109 b of the magnet 109 on the film formation substrate 1 side, and the surface of the film formation substrate 1 The distance may be 15 to 100 mm (preferably 20 to 50 mm).

  The magnet 109 has, for example, a cylindrical shape or a polygonal shape, and the center of the inner diameter of the cylindrical shape or the polygon is the magnet center, and the magnet center is the approximate center of the cathode filament 103 and the approximate center of the deposition target substrate 1. It is located so as to face each other. The magnet center is located closer to the approximate center of the film formation substrate 1 than the approximate center of the cathode filament 103.

  The magnet 109 has the north pole facing the cathode filament 103 and the south pole facing the film formation substrate 1.

  In addition, the plasma CVD apparatus has an evacuation mechanism (not shown) for evacuating the chamber 102. Further, the plasma CVD apparatus has a gas supply mechanism (not shown) for supplying a film forming raw material gas into the chamber 102 from the gas introduction part 102a.

<Film formation method>
A method of forming a DLC (Diamond Like Carbon) film on the deposition target substrate 1 using the plasma CVD apparatus shown in FIG. 1 will be described.

First, the vacuum evacuation mechanism is activated, the inside of the chamber 102 is brought into a predetermined vacuum state, and, for example, toluene (C ₇ H ₈ ) gas is used as a film forming source gas from the gas introduction unit 102 a to the inside of the chamber 102 by the gas introduction mechanism. Is introduced. After the chamber 102 reaches a predetermined pressure, the cathode filament 103 is heated by supplying an alternating current to the cathode filament 103 from the cathode power source 105.

  Further, a direct current is supplied to the deposition target substrate 1 by a DC power source 112. Further, a direct current is supplied from the DC power source 107 to the anode cone 104. Further, a magnetic field is formed by the magnet 109 in the vicinity of the surface of the deposition target substrate 1 and at a position facing it.

  By heating the cathode filament 103, a large amount of electrons are emitted from the cathode filament 103 toward the anode cone 104, and glow discharge is started between the cathode filament 103 and the anode cone 104. Toluene gas as a film forming material gas inside the chamber 102 is ionized by a large amount of electrons, and a plasma state 109a is obtained. The deposition raw material molecules in the plasma state are directly accelerated by the negative potential of the deposition target substrate 1, fly toward the deposition target substrate 1, and adhere to the surface of the deposition target substrate 1. Is done. At this time, film forming raw material molecules directed toward the surface of the film formation substrate 1 can fly with higher uniformity by the magnetic field generated by the magnet 109. As a result, a DLC film with good film thickness uniformity can be formed on the deposition target substrate 1. In particular, the controllability of the thickness of the film formed on the outer peripheral portion of the deposition target substrate 1 can be improved. The reaction of the following formula (1) occurs on the surface of the film formation substrate 1.

C ₇ H ₈ + e ⁻ → C _a H _b + xH ₂ ↑ (1)

  Next, a method for manufacturing a magnetic recording medium using the plasma CVD apparatus shown in FIG. 1 will be described.

  First, a film formation substrate having at least a magnetic layer formed on a nonmagnetic substrate is prepared, and this film formation substrate is held by a holding unit. Next, the source gas is turned into a plasma state by discharge between the cathode filament 103 and the anode cone 104 heated in the chamber 102 under a predetermined vacuum condition, and this plasma is formed on the film formation substrate held in the holding portion. Accelerate collision with the surface. As a result, a protective layer mainly composed of carbon is formed on the surface of the film formation substrate.

  According to the above method for manufacturing a magnetic recording medium, a DLC film with good film thickness uniformity can be formed on the film formation substrate 1 by the magnetic field formed by the magnet 109. In particular, the controllability of the thickness of the film formed on the outer peripheral portion of the deposition target substrate 1 can be improved.

[Embodiment 2]
<Plasma CVD equipment>
FIG. 2 is a cross-sectional view schematically showing a plasma CVD apparatus according to one embodiment of the present invention. The same parts as those in FIG. This plasma CVD apparatus has a symmetrical structure with respect to a film formation substrate (for example, a disk substrate) 1 and can form films on both surfaces of the film formation substrate 1 simultaneously. Only shows.

  2n magnets (for example, neodymium magnets) 119 are disposed inside the chamber 102 and outside the outer shield 90, and the 2n magnets 119 are disposed so as to surround the inner shield 108. However, n may be an integer of 2 to 12, but n may be an integer of 4 to 10.

  Each of the 2n magnets 119 has one of the N and S poles facing the inside of the inner shield 108, the other of the N and S poles facing the outside of the inner shield 108, and the adjacent magnets 119 are The magnetic poles facing the inner shield 108 are reversed. For example, when four magnets 119 are arranged, the magnetic field 119 a is formed by the magnets 119 so as to face the surface of the deposition target substrate 1. When eight magnets 129 are arranged, a magnetic field 129 a is formed by these magnets 129 so as to face the surface of the deposition target substrate 1.

  The distance between the plane 119c parallel to the surface of the film formation substrate 1 (the surface on the magnet 119 side) and including the end 119b of the magnet 119 on the film formation substrate 1 side is 15 to 15 mm. It is good that it is 100 mm (preferably 20-50 mm).

  The 2n magnets 119 are arranged so as to have, for example, a cylindrical shape or a polygonal shape, and the center of the inner diameter of the cylindrical shape or the polygonal shape is a magnet center 119d. The film substrate 1 is positioned so as to face each of the approximate centers. The magnet center 119d is located closer to the approximate center of the deposition target substrate 1 than the approximate center of the cathode filament 103.

  The magnetic field formed on the outer periphery of the deposition target substrate 1 by the magnets 119 and 129 may be ± 0.1 G (Gauss) to ± 50 G (preferably ± 1 G to ± 40 G). This is a range obtained from the result of measuring the magnetic field by installing four magnets 119, eight magnets 119, sixteen magnets 119, and twenty-four magnets 119 in the plasma CVD apparatus. By setting it as such a range, the controllability of the thickness of the film | membrane formed in the outer peripheral part of the to-be-deposited substrate 1 can be improved.

  The outer periphery of the film formation substrate 1 corresponds to, for example, a circumference having a radius of 32.5 mm from the magnet center 119d when the film formation substrate is a 2.5 inch substrate, and the film formation substrate is a 3.5 inch substrate. This corresponds to a circumference having a radius of 47.5 mm from the magnet center 119d.

<Film formation method>
A method for forming a DLC film on the deposition target substrate 1 using the plasma CVD apparatus shown in FIG. 2 will be described.

First, the vacuum evacuation mechanism is activated, the inside of the chamber 102 is brought into a predetermined vacuum state, and, for example, toluene (C ₇ H ₈ ) gas is used as a film forming source gas from the gas introduction unit 102 a to the inside of the chamber 102 by the gas introduction mechanism. Is introduced. After the chamber 102 reaches a predetermined pressure, the cathode filament 103 is heated by supplying an alternating current to the cathode filament 103 from the cathode power source 105.

  Further, a direct current is supplied to the deposition target substrate 1 by a DC power source 112. Further, a direct current is supplied from the DC power source 107 to the anode cone 104. Further, the magnet 119 forms a magnetic field in the vicinity of the surface of the film formation substrate 1 and at a position facing it.

  By heating the cathode filament 103, a large amount of electrons are emitted from the cathode filament 103 toward the anode cone 104, and glow discharge is started between the cathode filament 103 and the anode cone 104. Toluene gas as a film forming raw material gas inside the chamber 102 is ionized by a large amount of electrons to be in a plasma state. The deposition raw material molecules in the plasma state are directly accelerated by the negative potential of the deposition target substrate 1, fly toward the deposition target substrate 1, and adhere to the surface of the deposition target substrate 1. Is done. At this time, film forming raw material molecules directed toward the surface of the film formation substrate 1 can fly with higher uniformity by a magnetic field generated by the magnet 119. As a result, a DLC film with good film thickness uniformity can be formed on the deposition target substrate 1. In particular, the controllability of the thickness of the film formed on the outer peripheral portion of the deposition target substrate 1 can be improved.

  Next, a method for manufacturing a magnetic recording medium using the plasma CVD apparatus shown in FIG. 2 will be described.

  First, a film formation substrate having at least a magnetic layer formed on a nonmagnetic substrate is prepared, and this film formation substrate is held by a holding unit. Next, the source gas is turned into a plasma state by discharge between the cathode filament 103 and the anode cone 104 heated in the chamber 102 under a predetermined vacuum condition, and this plasma is formed on the film formation substrate held in the holding portion. Accelerate collision with the surface. As a result, a protective layer mainly composed of carbon is formed on the surface of the film formation substrate.

  According to the above method for manufacturing a magnetic recording medium, a DLC film with good film thickness uniformity can be formed on the film formation substrate 1 by a magnetic field formed by the magnet 119. In particular, the controllability of the thickness of the film formed on the outer peripheral portion of the deposition target substrate 1 can be improved.

Example 1
FIG. 3A is a photograph in which the DLC film 10 is formed on the deposition target substrate 1 using the plasma processing apparatus shown in FIG. 2, and FIG. 3B is the deposition shown in FIG. 1 is a cross-sectional view schematically showing the thickness of a DLC film 10 formed on a film substrate 1. FIG.

The conditions when the DLC film 10 shown in FIGS. 3A and 3B is formed are as follows.
Deposition apparatus: 16 magnets arranged on the plasma CVD apparatus shown in FIG. 2. Deposition substrate 1: Glass disk with metal layer Starting material: High-purity toluene Gas flow rate: 3.0 sccm
Pressure: 0.3 Pa
Deposition time: 2 sec × 5 times Cathode filament 103: Tantalum filament Output of AC power supply 105: 230 W
Current of DC power supply 107: 1650 mA
Voltage of DC power supply 112: 250V

(Comparative Example 1)
4A is a photograph in which the DLC film 11 is formed on the deposition target substrate 1 using an apparatus in which the magnet 119 is removed from the plasma CVD apparatus shown in FIG. 2, and FIG. It is sectional drawing which shows typically the film thickness of the DLC film 11 formed into the film-forming substrate 1 shown to (A).

The conditions when the DLC film 11 shown in FIGS. 4A and 4B is formed are as follows.
Deposition apparatus: apparatus excluding magnet 119 from the plasma CVD apparatus shown in FIG. 2 Deposition substrate 1: Glass disk with metal layer Starting material: High purity toluene Gas flow rate: 3.0 sccm
Pressure: 0.3 Pa
Deposition time: 2 sec × 5 times Cathode filament 103: Tantalum filament Output of AC power supply 105: 230 W
Current of DC power supply 107: 1650 mA
Voltage of DC power supply 112: 250V

  In the above comparative example, as shown in FIG. 4B, the thickness of the DLC film 11 near the outer periphery of the deposition target substrate 1 is increased. ), The film thickness of the DLC film 10 in the vicinity of the outer periphery of the deposition target substrate 1 was thinner than that in the comparative example. Therefore, it was confirmed that the thickness of the film formed on the film formation substrate 1 by the magnetic field of the magnet can be controlled with higher uniformity than in the comparative example.

1 Substrate to be deposited 10, 11 DLC film 90 Outer shield 102 Chamber 103 Cathode electrode (cathode filament)
104 Anode electrode (anode cone)
105 Cathode power supply (AC power supply)
106 Ground power source 107 Anode power source (DC (direct current) power source)
108 Inner shield 109, 119, 129 Magnet 109a Plasma 119a, 129a Magnetic field 112 Bias power supply (DC power supply, DC power supply)
118 Thickness Correction Plate 140 Cathode Magnet 140a Magnetic Field 1109, 1119, 1129, 1139 External Magnet 1109a, 1119a, 1129a, 1139a Magnetic Field

Claims (7)

A chamber;
An anode disposed in the chamber;
A cathode disposed within the chamber;
A holding unit arranged in the chamber and holding a deposition target substrate arranged to face the cathode and the anode;
An inner shield disposed in the chamber and provided so as to cover a space between the deposition target substrate held by the holding unit and each of the anode and the cathode;
A magnet disposed in the chamber, disposed outside the inner shield, and disposed so as to surround the inner shield;
A first DC power supply electrically connected to the anode;
An AC power source electrically connected to the cathode;
A second DC power source electrically connected to the film formation substrate held by the holding unit;
A gas supply mechanism for supplying a source gas into the chamber;
An exhaust mechanism for exhausting the chamber;
Comprising
The plasma is characterized in that a distance between a plane parallel to the surface of the film formation substrate and including an end of the magnet on the film formation substrate side and the surface of the film formation substrate is 15 to 100 mm. CVD equipment. In claim 1,
The inner shield is surrounded by 2n magnets,
Each of the 2n magnets has one of the north and south poles facing the inner shield, and the adjacent magnets have opposite magnetic poles facing the inner shield. CVD equipment.
However, n is an integer of 2-12. In claim 2,
A plasma CVD apparatus characterized in that a magnetic field around the deposition substrate is within a range of ± 0.1 G to ± 50 G. In claim 1,
The inner shield is surrounded by one magnet,
The plasma CVD apparatus according to claim 1, wherein the one magnet has one of an N pole and an S pole facing the cathode side and the other of the N pole and the S pole facing the deposition target substrate side. In any one of Claims 1 thru | or 4,
An outer shield disposed within the chamber and disposed outside the inner shield;
The plasma CVD apparatus, wherein the magnet is located outside the outer shield. In the manufacturing method of the magnetic-recording medium using the plasma CVD apparatus as described in any one of Claims 1 thru | or 5,
Holding the film formation substrate on which at least the magnetic layer is formed on the nonmagnetic substrate in the holding unit,
The source gas is brought into a plasma state by discharge between the cathode and the anode in the chamber, and the plasma is accelerated and collided with the surface of the film formation substrate held in the holding portion, so that carbon is a main component. A method for producing a magnetic recording medium, comprising forming a protective layer. In a method for manufacturing a magnetic recording medium, in which a protective layer mainly composed of carbon is formed after forming at least a magnetic layer on a nonmagnetic substrate.
A method for producing a magnetic recording medium, comprising forming the protective layer using the plasma CVD apparatus according to claim 1.