Abstract:
A composite coating device includes first to third processing chambers. The first processing chamber performs an ion beam etching as a pretreatment process in which an ion beam is irradiated on a surface of a magnetic head at a predetermined angle and the surface is removed for a predetermined depth. The second processing chamber performs a magnetron sputter deposition as a shock absorbing coating formation process in which a shock absorbing coating is formed on the pretreated surface. The third processing chamber performs an electron cyclotron resonance plasma chemical vapor epitaxy or a cathode arc discharge deposition as an overcoat formation process in which an overcoat is formed on the shock absorbing coating. A preparation chamber communicates with the first to third processing chambers through opening and closing devices for transferring the magnetic head.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT  
         [0001]    The present invention relates to a composite coating device for forming a composite coating on a magnetic head and a method of forming a composite coating on a magnetic head.  
           [0002]    In a magnetic storage device, a magnetic head is used to record and retrieve data stored in a magnetic storage media. For example, in a hard drive (HD) magnetic storage device in which data is recorded on a magnetic disk, when a magnetic head records and retrieves (access) data, the magnetic head rises from a disk surface only for a predetermined distance. When the magnetic head does not access data, the magnetic head lands on the disk surface in a so-called CSS (contact start and stop) mechanism.  
           [0003]    As described above, when the magnetic head does not access data, the magnetic head receives a shock from the disk. The magnetic head also receives a corrosive action through atmospheric moisture and the like, so that wear resistance and corrosion resistance are required for an overcoat of the magnetic head. In addition, as the recording density has been increasing, it is required to reduce a thickness of the overcoat to reduce a distance between an electrode of the magnetic head and a recording layer on the magnetic disk (flight height).  
           [0004]    In general, an overcoat of the magnetic head is formed through a manufacturing process comprising (1) a pretreatment process in which a coating surface of a head body is cleaned; (2) a shock absorbing coating formation process in which an amorphous silicon coating is formed; and (3) an overcoat formation process in which a DLC coating is formed. A composite coating device is used to carry out the processes in three independent processing chambers, respectively. The composite coating device performs a sputter etching for the pretreatment process, sputter deposition for the shock absorbing coating formation process, and electron cyclotron resonance plasma chemical vapor epitaxy or cathode arc discharge deposition for the overcoat formation process (refer to Japanese Patent Publication (Kokai) No. 2001-195717).  
           [0005]    When the sputter etching is used for the pretreatment process, there is the following problem. An overcoat is formed on a surface of a magnetic head. The surface includes a portion formed of a soft electrode metal, for example, Permalloy, and a portion formed of a hard base metal, for example, AlTic (Al 2 O 3 TiC). Accordingly, the portions of the surface are etched at different etch rates, i.e. the portion formed of Permalloy is etched at a higher speed, thereby forming a recessed portion on the surface. As a result, the flight height increases, thereby making it difficult to obtain high recording density.  
           [0006]    In view of the problem described above, an object of the present invention is to provide a composite coating device and an overcoat formation method, in which an overcoat is formed on a magnetic head while a fright height in the magnetic recording is reduced.  
           [0007]    Further objects and advantages of the invention will be apparent from the following description of the invention.  
         SUMMARY OF THE INVENTION  
         [0008]    In order to attain the objects described above, according to a first aspect of the present invention, a composite coating device includes a first processing chamber for performing ion beam etching as a pretreatment process in which an ion beam is irradiated on a surface of a magnetic head at a predetermined angle and the surface is removed for a predetermined depth; a second processing chamber for performing magnetron sputter deposition as a shock absorbing coating formation process in which a shock absorbing coating is formed on the pretreated surface; a third processing chamber for performing electron cyclotron resonance plasma chemical vapor epitaxy as an overcoat formation process in which an overcoat is formed on the surface with the shock absorbing coating formed thereon; and a preparation chamber communicating with the first to third processing chambers through opening and closing means for transferring the magnetic head.  
           [0009]    According to a second aspect of the present invention, a composite coating device includes a composite coating device includes a first processing chamber for performing ion beam etching as a pretreatment process in which an ion beam is irradiated on a surface of a magnetic head at a predetermined angle and the surface is removed for a predetermined depth; a second processing chamber for performing magnetron sputter deposition as a shock absorbing coating formation process in which a shock absorbing coating is formed on the pretreated surface; a third processing chamber for performing cathode arc discharge deposition as an overcoat formation process in which an overcoat is formed on the surface with the shock absorbing coating formed thereon; and a preparation chamber communicating with the first to third processing chambers through opening and closing means for transferring the magnetic head.  
           [0010]    According to a third aspect of the present invention, in the composite coating devices in the first and second aspects, an ion beam etching device includes an ion source provided with an electrode for obtaining ions having a first grid with positive potential and a second grid with negative potential; and a communicating portion for eliminating an effect of the potential of the second grid relative to an electron in a plasma production area and for communicating a plasma production area with an outside of the plasma production area. The ion beam etching device may be provided with a dielectric block for adjusting a plasma density distribution at a plasma production portion. The ion beam etching device may also be provided with a high-frequency induction coupled plasma source including an electric insulation dividing wall projecting into the plasma production area and separating the plasma production chamber from outside, and an excitation coil provided in an outer concave portion of the electric insulation dividing wall.  
           [0011]    In the composite coating device, the shock absorbing coat is formed of a silicon layer, and the overcoat is formed of a carbon layer. Especially, the silicon layer may be formed of an amorphous silicon, and the carbon layer is formed of one of a diamond-like carbon (DLC) layer or a tetrahedral amorphous carbon (ta-C) layer.  
           [0012]    According to the present invention, a method of forming the overcoat on the magnetic head includes steps of the ion beam etching, the magnetron sputter deposition, and the electron cyclotron resonance plasma chemical vapor epitaxy in this order using the composite coating device described above.  
           [0013]    According to the present invention, a method of forming the overcoat on the magnetic head may include steps of the ion beam etching, the magnetron sputter deposition, and the cathode arc discharge deposition in this order using the composite coating device described above.  
           [0014]    According to the present invention, the magnetic head is formed with one of the overcoat formation methods described above. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a schematic view showing a structure of a composite coating device according to an embodiment of the present invention;  
         [0016]    [0016]FIG. 2 is a schematic view showing a structure of an ion beam etching device according to the embodiment of the present invention;  
         [0017]    [0017]FIG. 3 is a schematic view showing a structure of a magnetron sputter deposition device;  
         [0018]    [0018]FIG. 4 is a schematic view showing a structure of an electron cyclotron resonance plasma chemical vapor epitaxy device;  
         [0019]    [0019]FIG. 5 is a schematic view showing a structure of a cathode arc discharge deposition device;  
         [0020]    [0020]FIG. 6 is a schematic view showing a first modified example of the ion beam etching device according to the embodiment of the present invention;  
         [0021]    [0021]FIG. 7 is a schematic view showing a second modified example of the ion beam etching device according to the embodiment of the present invention;  
         [0022]    FIGS.  8 ( a ) to  8 ( c ) are sectional views of a magnetic head, wherein FIG. 8( a ) is a sectional view showing a state that a substrate is etched with an IBE device, FIG. 8( b ) is a sectional view showing a state wherein an amorphous silicon coat and a DLC coat are formed on the substrate after the etching, and FIG. 8( c ) is a sectional view showing an actual state of the substrate;  
         [0023]    [0023]FIG. 9 is a graph showing etching performance of the ion beam etching device according to the embodiment of the present invention;  
         [0024]    [0024]FIG. 10 is a graph showing etching performance of a conventional sputter etching device;  
         [0025]    [0025]FIG. 11 is a graph showing an optical characteristic of reflective index of an amorphous silicon coat formed with a magnetron sputter deposition device according to the embodiment of the present invention;  
         [0026]    [0026]FIG. 12 is a graph showing an optical characteristic of absorption coefficient of the amorphous silicon coat formed with a magnetron sputter deposition device according to the embodiment of the present invention; and  
         [0027]    FIGS.  13 ( a ) and  13 ( b ) are graphs showing Raman spectrum of carbon layers formed with an ECR-CVD device and a FCVA device according to the embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0028]    Hereunder, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic view showing a structure of a composite coating device according to an embodiment of the present invention.  
         [0029]    As shown in FIG. 1, a composite coating device  1  includes a cassette chamber  2  wherein a substrate  100  with a plurality of magnetic heads arranged thereon is taken in and out; a conveyance chamber  3  wherein the substrate  100  is transferred; an IBE device  10  for performing ion beam etching (hereinafter, referred to as IBE); a MSD device  30  for performing magnetron sputter deposition (hereinafter, referred to as MSD); and an ECR-CVD device  40  for performing electron cyclotron resonance plasma chemical vapor epitaxy (hereinafter, referred to as ECR-CVD). The conveyance chamber  3  is connected with the IBE device  10 , the MSD device  30 , and the ECR-CVD device  40  through gates  5 ,  6  and  7 , respectively. The substrate  100  inside the conveyance chamber  3  is conveyed to each device by a conveyance mechanism  4 , and the substrate  100  inside each device is carried in the conveyance chamber  3  by the conveyance mechanism  4 .  
         [0030]    In the embodiment, the composite coating device  1  is used for forming an overcoat on the magnetic head. Before the overcoat formation, an electrode metal, a base metal, and the like are exposed on an overcoat formation surface (protected surface) of the substrate  100 . The composite coating device  1  carries out one process in one chamber, so that it is possible to prevent mutual contamination between the processing chambers. Also, the substrate  100  is consecutively processed without being exposed to the atmosphere in the middle of the processing, so that it is possible to prevent oxidation of the substrate  100 , sticking of a dust, and the like.  
         [0031]    The substrate  100  is transferred to the IBE device  10  from the conveyance chamber  3 , and the etching process is carried out on the protected surface in the IBE device  10 . In the etching process, the protected surface of the substrate  100  is removed as much as 20 nm in depth as the cleaning process before the amorphous silicon coat is formed. As shown in FIG. 2, the IBE device  10  is provided with an ion source  11  and a process camber  12  wherein the etching process is carried out. The ion source  11  is formed of electrodes  18  for leading out ions in a plasma source  13 , i.e. plasma production means.  
         [0032]    The plasma source  13  is a high-frequency induction coupled plasma source for generating plasma through high-frequency induction coupling. A high-frequency introductory window  14  is provided in a plasma chamber  19  of the plasma source  13 , and flat-surface excitation coils  15  are provided outside the high-frequency introductory window  14  for generating high frequencies. A RF power source  16  is connected to the excitation coils  15  for supplying a high-frequency electric current of 13.56 MHz. A dielectric material such as quartz, ceramic, and the like is used for the high-frequency introductory window  14 . A matching circuit (not shown) is provided between the excitation coil  15  and the RF power source  16  for matching impedance.  
         [0033]    In the plasma chamber  19 , gas for plasma production is introduced via a gas supply source  17 . In the present embodiment, argon gas is used as an example. Grids  18   a ,  18   b , and  18   c  constituting the electrodes  18  for leading out ions are provided at an opening of the plasma chamber  19 . A positive potential V 1  is supplied to the grids  18   a  via a grid power source  20   a , and a negative potential (−V 2 ) is supplied to the grids  18   b  via a grid power source  20   b . The grids  18   c  have earth potential Vg, and the plasma chamber  19  has potential (V 1 ) same as that of the grids  18   a.    
         [0034]    In the embodiment, an electron port  21  made of a conductive material is provided in the electrodes  18  for leading out ions. The electron port  21  (described below) is attached to the grids  18   a , and has the same potential (V 1 ) as that of the grids  18   a . A substrate holder  23  is provided in the process chamber  12  for holding the substrate  100  as an etching object. The substrate holder  23  is arranged to be tiltable as shown by R 1 , and rotatable as shown by R 2 . A vacuum pump (not shown) is connected to an exhaust port  12   a  for evacuating the inside of the process chamber  12 .  
         [0035]    When argon gas is introduced into the plasma chamber  19  and high frequency generated at the excitation coil  15  is introduced into the plasma chamber  19  from the high-frequency introductory window  14 , electrons are separated from argon atoms, and plasma including argon ions Ar +  and electrons e are generated. The argon ions Ar +  are accelerated with an electric field between each positive potential grid  18   a  and each negative potential grid  18   b  and then, decelerated between each grid  18   b  and each earth potential grid  18   c . In the end, ion beams IB having energy corresponding to a potential difference between the grids  18   a  and the grids  18   c  are formed.  
         [0036]    The accelerated argon ions Ar +  irradiate on the substrate  100 , and etch the surface of the substrate. When the substrate  100  is made of a conducting material, a positive charge of argon ions Ar +  irradiating on the substrate  100  flows to the substrate holder  23  connected to the substrate  100 . When the substrate,  100  is made of an insulation material such as SiO 2 , the positive charge is accumulated on the surface of the substrate and the potential of the substrate increases, as shown in FIG. 2. The electric field between the grids  18   a  and the grids  18   b  prevents electronegative electrons e from leaking in the process chamber  12 .  
         [0037]    As shown in FIG. 2, a tubular portion of the electron port  21  with the same potential as the grids  18   a  extends to the grids  18   c . Accordingly, the grids  18   b  do not affect the inside of the tubular portion, thereby forming an approximately equal potential inside the tubular portion. As a result, there is no electric field preventing the electrons e from moving, so that the electrons e can easily move toward the process chamber  12 . When the substrate  100  is positively charged, the electrons e can easily move toward the positive direction, so that the electrons e inside the plasma chamber  19  are led out of the electron port  21  toward the substrate  100  and irradiate on the substrate  100 .  
         [0038]    When the positive charge is not accumulated on the substrate  100 , the electrons e are not led out through the electron port  21 . Accordingly, the electrons e corresponding to an amount of the positive charge accumulated on the substrate  100  irradiate on the substrate  100  through the electron port  21  from the plasma chamber  19 , so that the positive charge of the substrate  100  is neutralized.  
         [0039]    As described above, the electron port  21  is provided in the electrodes  18 , and the grids  18   b  do not prevent the electrons e from moving toward the process chamber. As a result, the electrons e inside the plasma move toward the electropositive substrate  100  to neutralize the positive charge of the substrate  100 , so that the etching effect of the argon ion Ar +  is maintained.  
         [0040]    Also, the electrons e irradiate on the substrate  100  for the amount automatically determined by the charged amount of the substrate  100 , so that it is not necessary to adjust the amount of the electrons without a problem of too small or too large amount. The electrons e move faster compared to the argon ions Ar + , the electrons e neutralize quickly when the substrate  100  is charged in positive. Specifically, just the electron port  21  is provided in the electrodes  18 , thereby reducing cost as compared to a conventional method wherein a heater for thermal emission or another plasma source is provided.  
         [0041]    Next, etching characteristics of the substrate  100  with the IBE device will be explained. FIG. 8( a ) is a partial cross sectional view showing a state that the substrate  100  is etched with the IBE device. FIG. 8( b ) is a partial cross sectional view showing a state wherein an amorphous silicon coat  103  and a DLC coat  104  are formed on the substrate  100  after the etching. A line A 1  indicates the surface (protected surface) formed of a base metal  101  and an electrode metal  102  before the etching. A line A 2  indicates a surface after only a depth D is removed by the etching with the IBE device.  
         [0042]    As shown in FIGS.  8 ( a ) and  8 ( b ), the base metal  101  and the electrode metal  102  have different etch rates, so that an actual A 2  looks more like A 3  shown in FIG. 8( c ). For example, when Al 2 O 3 TiC is used for the base metal  101  and FeNi (Permalloy) is used for the electrode metal  102 , the softer Permalloy is deeply etched, and a step d is formed as shown in FIG. 8( c ). Therefore, the flight height increases by the step, so that it is difficult to obtain a high record density.  
         [0043]    In addition, when the step d is formed, it is difficult to properly form the amorphous silicon coat  103  and the DLC coat  104 . The amorphous silicon coat  103  and the DLC coat  104  have small thicknesses. Accordingly, even though the step d may be small, it is difficult to cover the step, thereby causing a micro-crack or residual stress, and lowering corrosion resistance.  
         [0044]    As shown in FIG. 10, in conventional sputter etching (SE), an etch rate of FeNi is higher than that of Al 2 O 3 TiC. When RF electric power is 200 W, the etch rate of FeNi is three times higher than that of Al 2 O 3 TiC, and when the RF electric power is 300 W, the etch rate of FeNi is 3.2 times higher than that of Al 2 O 3 TiC. On the other hand, as shown in FIG. 9, in the IBE of the present embodiment, etch rates of the FeNi and Al 2 O 3 TiC are function of an inclined angle of the substrate  100  relative to the ion beam, and when the inclined angle is 75°, the difference becomes a minimum. The substrate holder  23  tilts as shown by R 1  to change the inclined angle. Since the ion beam has directivity, the etch rate of a different material can be adjusted by the inclined angle. As a result, the step d shown in FIG. 8( c ) becomes very small, so that the magnetic head coated with the amorphous silicon coat  103  and the DLC coat  104  reduces the flight height. Also, since the step d is very small, it is easy to form the amorphous silicon coat  103  and the DLC coat  104 , so that the corrosion resistance of the overcoat is improved.  
         [0045]    After the etching process, the substrate  100  is conveyed to the conveyance chamber  3  and then to the MSD device  30  through the gate  5 . FIG. 3 is a view showing the DC type MSD device for forming the amorphous silicon coat, and the amorphous silicon coat is formed with a thickness of 0.5 nm. A silicone (Si) target  31  is placed on a target holder  39  provided in a sputter chamber  37  of the MSD device  30 . The target holder  39  is a cathode, and the substrate  100  is attached to an anode  32 . The substrate  100  is held in such a way that the coated surface faces down. A magnet  33  is provided in the target holder  39 , and a negative bias voltage is applied the Si target  31  from a bias power source  34 . The magnet  33  is provided for generating a parallel magnetic field around a surface of the Si target  31 . Argon gas (Ar) is supplied as process gas to the sputter chamber  37 . The argon gas is supplied from a supply source  35  through a mass-flow controller  36   a  and a valve  36   b  of a gas feeding device  36 .  
         [0046]    In the coating process, the argon gas is supplied to the sputter chamber  37 , and a vacuum device  38  evacuates the inside of the sputter chamber  37 , so that the inside of the sputter chamber  37  has a predetermined process pressure and plasma is generated. The Si target  31  is sputtered by the argon ion in the plasma, and sputtered Si particles are accumulated on the coated surface of the substrate  100  and form the amorphous silicon coat.  
         [0047]    After the coating process of the amorphous silicon coat, the substrate  100  is conveyed to the conveyance chamber  3  through the gate  6 , and then to the ECR-CVD device  40  through the gate  7 . FIG. 4 is a view of the ECR-CVD device for forming the DLC (diamond-like carbon) coat, and the DLC coat is formed with a thickness of 1 nm. The ECR-CVD device  40  comprises a reaction chamber  41  for forming a thin coat on the substrate  100  with the amorphous silicon coat formed thereon; an ECR plasma generation portion  42  for introducing plasma into the reaction chamber  41 ; a bias power source portion  43  for applying a bias voltage to the substrate  100 ; and a control portion  45  for controlling the whole device, coating conditions, and a reaction gas introductory portion  44  to introduce reactive gas into the reaction chamber  41 .  
         [0048]    The ECR plasma generation portion  42  is a mechanism for supplying microwave electric power to the magnetic field to generate the electron cyclotron resonance plasma, and for introducing the plasma flow into the reaction chamber  41 . A microwave source  46  generates a microwave of 2.45 GHz, and the microwave is introduced into a plasma chamber  47  through a wave guide  46   a  to discharge the microwave. In addition, a magnetic flux density 875 G at the ECR condition is formed with the magnetic filed generated by coils  46   b  and  46   c  to generate electron cyclotron resonance, so that activated ECR plasma is generated. The ECR plasma generated inside the plasma chamber  47  moves toward the substrate  100  inside the reaction chamber  41  along the divergent magnetic field from the plasma window  47   a.    
         [0049]    In the bias power source portion  43 , a bias power source  43   a  is connected to a substrate holding mechanism inside the reaction chamber  41  through a matching unit  43   b , and a negative bias voltage. is applied to the substrate  100  disposed inside the reaction chamber  41 . A voltage monitor  43   c  measures the bias voltage. The reactive gas introduced into the reaction chamber  41  from the reaction gas introductory portion  44  is ionized inside the high density plasma generated by the ECR, and the DLC coat is formed on the substrate  100  with the negative bias voltage. When the DLC coat is formed, ethylene (C 2 H 4 ), methane (CH 4 ), propane (C 3 H 8 ), or the like is provided through the reaction gas introductory portion  44  as coating gas. An exhaust pump  44   d  exhausts the reaction chamber  20 , and a pressure gauge  44   e  measures the pressure inside the reaction chamber  20 .  
         [0050]    Instead of the ECR-CVD device forming the DLC coat, a cathode arc discharge deposition device may form a ta-C (tetrahedral amorphous carbon) coat. FIG. 5 is a view of an FCVA (Filtered Cathode Vacuum Arc) device as the cathode arc discharge deposition device. A carbon ion generation source  51  generates a carbon ion C +  via vacuum arc discharge between a cathode  52  and an anode  53 . The cathode  52  is formed in a disk shape made of high-purity graphite. The carbon ions C +  generated at the carbon ion generation source  51  are coated on the substrate  100  after passing through a filter  54 . The filter  54  allows only required carbon ions to pass through using the electric field and the magnetic filed, and the filter  54  removes large carbon particles or neutral carbon atoms.  
         [0051]    Magnetic coils  55  are provided near an exit of the filter  54  for scanning carbon ion beams, so that the ta-C coat is uniformly formed on the substrate  100 . A bias voltage is applied to the substrate  100 , and energy of the ions arriving at the substrate  100  depends on the bias voltage, so that the coating characteristics can be adjusted through the bias voltage.  
         [0052]    [0052]FIG. 6 is a view showing a modified example of the IBE device. The IBE device  60  is composed of a plasma production portion  61  and a vacuum chamber  62 . The substrate  100 , i.e. the etching object, is placed in the vacuum chamber  62 . The plasma production portion  61  is disposed at a position facing the substrate  100  inside the vacuum chamber  62 . The plasma production portion  61  comprises a plasma chamber  63  including a cylindrical plasma formation space; antenna coils  64 ; and a high-frequency power  65 . The plasma production portion  61  generates plasma with an inductive coupled plasma excitation method.  
         [0053]    A dielectric window  63   a  formed of ceramic and the like is provided at a bottom surface of the plasma chamber  63 . The antenna coils  64  are provided at outside the dielectric window  63   a . The antenna coils  64 A forms a high-frequency magnetic field inside the plasma chamber  63  through the dielectric window  63   a . A cylindrical dielectric block  66  is provided inside the plasma chamber  63  for adjusting a plasma distribution. When plasma production gas (for example, argon gas) is supplied into the plasma chamber  63  through a gas supply device  67  and the antenna coils  64  form the high-frequency magnetic field, plasma P is generated inside the plasma chamber  63 . A porous electrode grid G for leading out ions is provided at an opening of the plasma chamber  63 . Charged particles such as ions are led out of the plasma chamber  63  via the grid G, and ion-beams IB are accelerated.  
         [0054]    In the plasma production portion  61 , the cylindrical dielectric block  66  is disposed coaxially with the antenna coils  64 . At this moment, the plasma P does not enter an area of the dielectric block including the internal space of the dielectric block  66 . As a result, the plasma P is distributed around the dielectric block  66  in a doughnut shape. A density distribution of the plasmas P is related to a distribution of an ion current value, i.e. a density distribution of the ion-beams IB. When the density distribution of the plasma has a doughnut shape around the coil shown in FIG. 6, the ion current value of the ion-beams IB led out of the plasma P has a two-top distribution wherein the center of the coil is a concave portion. It is possible to adjust the distribution of the current value by moving the dielectric block  66  inside the plasma P. In the etching process, the surface of the substrate  100  is removed as much as 20 nm in depth, and the cleaning is completed before the amorphous silicon coat is formed.  
         [0055]    [0055]FIG. 7 is a view showing another modified example of the IBE device. In an IBE device  70 , a stage  71  is provided inside a process chamber PC for placing the substrate  100 . A high-frequency induction coupled plasma source  72  is provided at a position facing the stage  71  in the process chamber PC. When the inside of the process chamber PC is evacuated via a vacuum pump VP during the etching process, the inside of a plasma production chamber  73  of the high-frequency induction coupled plasma source  72  is also evacuated in a decompressed state.  
         [0056]    A protrusion  73   a  projecting into the plasma production chamber  73  is provided at a midsection of the plasma production chamber  73 . An excitation coil  74  is disposed in a concave portion formed outside the protrusion  73   a  for forming an alternate current magnetic field M inside the plasma production chamber  73 . The protrusion  73   a  is formed of an insulator such as glass, ceramic, and the like, and functions as a high-frequency introductory window for introducing the alternate current magnetic field formed by the excitation coil  74  into the plasma production chamber  73 . The excitation coil  74  is a solenoid-type coil, and connected to a RF power source  76  through a matching device  75 . Incidentally, in the present embodiment, the excitation coil  74  is the solenoid-type coil, and may be a flat-type coil with one tern.  
         [0057]    The RF power source  76  uses a frequency from 1 to 100 MHz for an economical reason, and the high-frequency power of 13.56 MHz is used in the present embodiment. A capacitor for matching impedance is provided in the matching device  75 . By adjusting a capacitance of the capacitor, a matching condition can be adjusted. When plasma is generated, argon gas or the like is introduced into the plasma production chamber  73  from a gas supply source  77 .  
         [0058]    Ring-shaped magnets  78   a  and  78   b  are provided on an outer periphery of the plasma production chamber  73  for forming a static magnetic field in the plasma production chamber  73 . The magnets  78   a  and  78   b  are formed of an electromagnet, and may be formed of a permanent magnet. The magnets  78   a  and  78   b  form a cusped magnetic field. When the high-frequency voltage is applied to the excitation coil  74 , argon gas is excited via inductive coupling, and plasma P 1  including the argon ions is generated in a ring-shaped space between the plasma production chamber  73  and the protrusion  73   a . Electrons in the plasma P 1  are trapped by the cusped magnetic field, thereby facilitating the plasma production and efficiently forming the plasma P 1 .  
         [0059]    Grids G 1 , G 2 , and G 3  are provided at an opening of the plasma production chamber  73  for leading out the argon ions from the generated plasma P 1 . A grid power source  79  applies a grid voltage to the grids G 1  to G 3 . For example, a voltage of 800 V is applied to the grid G 1  and a voltage of 400 V is applied to the grid G 2 , respectively. The grid G 3  is grounded and has a potential of 0 V. When the voltages are applied to the grids G 1  to G 3 , the ion beams IB of the argon ions are led out of the plasma source  72  upwardly, and irradiate on the substrate  100 .  
         [0060]    In the plasma source  72  shown in FIG. 7, the protrusion  73   a  formed of an insulator projects into the plasma production chamber  73 , so that the plasma P 1  does not enter an area of the protrusion  73   a . As a result, the plasma P 1  is distributed between the protrusion  73   a  and the plasma production chamber  73  in a ring shape around the protrusion  73   a . In the etching process, the surface of the substrate  100  is removed as much as 20 nm in depth, and the cleaning process is completed before the amorphous silicon coat is formed.  
         [0061]    Finally, the amorphous silicon coat and the carbon coat formed with the composite coating device  1  of the present embodiment will be explained. FIG. 11 is a graph showing spectral characteristics of the amorphous silicon coat formed with the MSD device  30 , wherein the vertical axis represents a refractive index n and the horizontal axis represents a wavelength. FIG. 12 is a graph showing spectral characteristics of the amorphous silicon coat formed with the MSD device  30 , wherein the vertical axis represents an absorption coefficient k and the horizontal axis represents a wavelength. The refractive index n and the absorption coefficient k are indicators of a nature of the amorphous silicon coat.  
         [0062]    FIGS.  13 ( a ) and  13 ( b ) are graphs showing Raman spectra of the carbon layers formed with the ECR-CVD device and the FCVA device, wherein the vertical axis represents a signal strength and the horizontal axis represents a wavelength. FIG. 13( a ) shows the carbon layer formed with the ECR-CVD device and FIG. 13( b ) shows the carbon layer formed with the FCVA device. The spectra were analyzed with a peak resolution analysis to identify a component associated with a diamond structure (D) and a component associated with a graphite structure (G), and an area ratio of the peak areas, i.e. Area (D/G), was determined. The carbon layer formed with the ECR-CVD device has the Area (D/G) of 0.48, and the carbon layer formed with the FCVA device has the Area (D/G) of 0.34. The Area (D/G) is an indicator of a nature of the carbon layer.  
         [0063]    As explained above, according to the present invention, the substrate is tilted by a predetermined angle using the IBE, so that the step between the base metals and the electrode metal can be reduced. Accordingly, it is possible to form the overcoat on the magnetic head with a small flight height.  
         [0064]    While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims.