Abstract:
An arc evaporation source constituting this vacuum arc deposition apparatus has a plurality of cathodes, a trigger electrode, a trigger drive unit, a shutter, and a shutter drive unit. The trigger drive unit changes over the position of the trigger electrode to thereby position the trigger electrode in front of a desired cathode, and connects/disconnects the trigger electrode to/from the desired cathode in the changed-over position. The shutter covers the fronts of all the cathodes except the desired cathode..: The shutter drive unit moves the shutter to thereby change over the cathode not covered with the shutter. Further, the vacuum arc deposition apparatus has a changeover control unit for controlling the shutter drive unit and the trigger drive unit to thereby change over the cathode not covered with the shutter and to thereby position the trigger electrode in front of the cathode not covered with the shutter.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to vacuum arc deposition apparatus having an arc evaporation source for evaporating a cathode material due to vacuum arc discharge and depositing the cathode material on a substrate so as to form a thin film. It particularly relates to means for making it possible to prolong the film deposition time or to enhance the degree of freedom to form a laminated film.  
           [0003]    2. Description of the Related Art  
           [0004]    [0004]FIG. 4 shows an example of such vacuum arc deposition apparatus in the related art, and FIG. 5 shows a view taken from the arrow P.  
           [0005]    This vacuum arc deposition apparatus has a vacuum chamber  2  to be vacuum-evacuated by a not-shown vacuum pumping system. A holder  6  for holding a substrate  4  to be filmed is provided in the vacuum chamber  2 . An arc evaporation source  10  is attached to a side wall portion of the vacuum chamber  2  so as to face the substrate  4  on the holder  6  in this example.  
           [0006]    The arc evaporation source  10  evaporates a cathode material  16  from a cathode  14  due to vacuum arc discharge. More specifically, the arc evaporation source  10  has a cathode holder  12  made from a conductor (for example, non-magnetic metal) and for holding the cathode  14 . One cathode  14  is attached to the cathode holder  12  in the related art. The cathode holder  12  is attached to the vacuum chamber  2  through an insulator  18 .  
           [0007]    The arc evaporation source  10  further includes a trigger electrode  20  and a trigger drive unit  22 . The trigger electrode  20  is used for arc ignition in the cathode  14 . The trigger drive unit  22  moves the trigger electrode  20  in the front/rear direction of the cathode  14  through a shaft  24  and a feedthrough  26  so as to connect/disconnect (contact/separate) the trigger electrode  20  to/from the cathode  14  as shown by the arrow B. The feedthrough  26  has a vacuum seal function and an electrical insulating function in this example.  
           [0008]    The vacuum chamber  2  also serves as an anode of the arc evaporation source  10  in this example. Between the cathode  14  of the arc evaporation source  10  and the vacuum chamber  2  also serving as the anode, a DC arc power supply  28  for arc discharge is connected through the cathode holder  12  and with the cathode  14  on the negative side (in other words, with the vacuum chamber  2  on the positive side) . Between the trigger electrode  20  and the positive side of the arc power supply  28  (in other words, the anode or the vacuum chamber  2  also serving as the anode), a resistor  30  for limiting a current in arc ignition is connected through a conductive shaft  24 .  
           [0009]    An example of the operation will be described as follows. The trigger electrode  20  is moved by the trigger drive unit  22  so as to be once brought into contact with the cathode  14  to which a DC voltage (for example, about several tens of V) is applied from the arc power supply  28 . When the trigger electrode  20  is then separated from the cathode  14 , a spark occurs between the trigger electrode  20  and the cathode  14 . This triggers off continuous arc discharge between the cathode  14  and the vacuum chamber  2  also serving as the anode. Thus, the surface of the cathode  14  is melted so that the cathode material  16  is evaporated. Then, the cathode material  16  is injected and deposited onto the substrate  4  so that a thin film is formed on the surface of the substrate  4 .  
           [0010]    At that time, a negative bias voltage (for example, about minus several tens of V to about −1,000 V) may be applied from a bias power supply  8  to the substrate  4  on the holder  6 . Thus, the adhesion of the thin film to the substrate  4  is improved.  
           [0011]    In addition, the holder  6  holding the substrate  4  may be rotated in the arrow E direction or in the reverse direction thereto. Thus, the uniformity of the thin film on the substrate  4  is improved.  
           [0012]    In addition, reactive gas (for example, nitrogen gas) reactive to the cathode material  16  or inert gas (for example, argon) not reactive thereto may be introduced into the vacuum chamber  2 . When reactive gas is introduced, a compound thin film can be formed on the surface of the substrate  4 .  
           [0013]    Incidentally, an anode of the arc evaporation source  10  may be provided separately from the vacuum chamber  2 . In that case, the positive electrode of the arc power supply  28  and the resistor  30  are connected to the anode while the vacuum chamber  2  is typically grounded. The same thing can be applied to an arc evaporation source  10   a  constituting vacuum arc deposition apparatus according to the invention, which will be described later.  
           [0014]    Although one arc evaporation source  10  is illustrated here, a plurality of arc evaporation sources may be provided if necessary. For example, a total of two arc evaporation sources may be provided so that one is put on the left of the substrate  4  on the holder  6  and the other is put on the right thereof. Alternatively, a total of four arc evaporation sources may be provided so that two are put above and below on the left and the other two are put above and below on the right. The number of arc evaporation sources may be larger than four. The same thing can be applied to the arc evaporation source  10   a  which will be described later.  
           [0015]    In the vacuum arc deposition apparatus, the cathode  14  of the arc evaporation source  10  is consumed with film deposition. When the cathode  14  has been consumed beyond a certain limit, film deposition is blocked. Thus, the film deposition time is limited. When the cathode  14  is worn, it is necessary that the vacuum in the vacuum chamber  2  is broken to open the inside of the vacuum chamber  2  to the atmosphere and exchange the cathode  14  for a new one, and the vacuum chamber  2  is then vacuum-evacuated again. Thus, it takes much time for the exchange work.  
           [0016]    When a laminated film (for example, multilayer film) is formed on the surface of the substrate  4  by use of different kinds of cathodes  14 , that is, different kinds of cathode materials  16  from each other, kinds of films forming the laminated film are limited by the number of arc evaporation sources  10  aside from the kind of introduced gas. Thus, the degree of freedom to form the laminated film is low.  
         SUMMARY OF THE INVENTION  
         [0017]    It is therefore an object of the invention to provide vacuum arc deposition apparatus in which the time to deposit a film on a substrate can be prolonged or the degree of freedom to form a laminated film can be enhanced.  
           [0018]    In a vacuum arc deposition apparatus according to a first aspect of the invention, an arc evaporation source includes a cathode holder made from a conductor for holding the cathode, a plurality of cathodes attached to the cathode holder, a trigger electrode for arc ignition, a trigger drive unit for performing an operation to change over a position of the trigger electrode to thereby position the trigger electrode in front of a desired one of the plurality of cathodes and an operation to move the trigger electrode toward or to get apart from the desired cathode in the changed-over position, a shutter capable of covering fronts of all of the cathodes except the desired cathode, and a shutter drive unit for performing an operation to move the shutter to thereby change over a cathode not covered with the shutter.  
           [0019]    The vacuum arc deposition apparatus further includes a changeover control unit for making a changeover control to control the shutter drive unit and the trigger drive unit so as to change over a cathode not covered with the shutter while positioning the trigger electrode in front of the cathode not covered with the shutter.  
           [0020]    According to this vacuum arc deposition apparatus, one arc evaporation source has a plurality of cathodes, and the changeover control unit can change over a cathode not covered with the shutter while changing over the position of the trigger electrode so as to position the trigger electrode in front of the cathode not covered with the shutter. Accordingly, the plurality of cathodes can be used while being changed over in the condition that the vacuum chamber is not opened to the atmosphere. Thus, the film deposition operation can be carried out continuously with the plurality of cathodes.  
           [0021]    On that occasion, according to the invention, not only is the position of the trigger electrode changed over to change over the cathode to be used, but all the cathodes except the cathode to be used are also covered with the shutter. Accordingly, (a) the cathode material evaporated from the cathode in use can be prevented from adhering to the surface of any other unused cathode by the shutter. Further, (b) arc discharge in the cathode in use can be prevented from shifting to another unused cathode to thereby cause undesired arc discharge by the shutter.  
           [0022]    The kinds of the plurality of cathodes provided in the single arc evaporation source maybe made the same as one another or different from one another, or cathodes of the same kind and of different kinds may be mixed in the single arc evaporation source.  
           [0023]    When the kinds of cathodes are made the same as one another, the film deposition time can be prolonged in accordance with the number of cathodes in comparison with that when the number of cathodes is one. For example, the film deposition-time can be prolonged as many times as the number of cathodes.  
           [0024]    When the kinds of cathodes are made different from one another, a wide variety of films can be formed correspondingly. Thus, the degree of freedom to form a laminated film can be enhanced in comparison with that when the number of cathodes is one. In this case, the effect in the paragraph (a) due to the fact that all the cathodes except the cathode in use are covered with the shutter is particularly effective. That is, if there were, among the unused cathodes, a cathode not covered with the shutter, the cathode material evaporated from the cathode in use (which will be referred to as “first cathode”) would adhere to the surface of the cathode not covered with the shutter (which cathode will be referred to as “second cathode”). When a film is next formed with the second cathode, the cathode material adhering to the second cathode would be evaporated so that a film having a composition different from an intended composition would be formed on a substrate for a while. According to the invention, such a problem can be avoided.  
           [0025]    When cathodes of the same kind and of different kinds are mixed, not only is it possible to prolong the film deposition time but it is also possible to enhance the degree of freedom to form a-laminated film.  
           [0026]    For example, the changeover control unit performs the changeover control in response to a changeover instruction given from the outside (for example, an operator or the like). Alternatively, the changeover control may be performed automatically in the following manner.  
           [0027]    That is, in a vacuum arc deposition apparatus according to a second aspect of the invention, an arc current integrator may be further provided for integrating an arc current flowing into the arc power supply via the cathode holder during the current-carrying time so as to obtain an arc current amount, and the changeover control unit is designed to carry out the changeover control whenever the arc current amount obtained by the arc current integrator exceeds a predetermined reference value.  
           [0028]    The arc current amount obtained by the arc current integrator is proportional to the degree of consumption of the cathode which is in use at that time. Accordingly, with the configuration, a cathode to be used can be changed over automatically whenever the consumption of the cathode in use reaches a predetermined quantity of consumption.  
           [0029]    In a vacuum arc deposition apparatus according to a third aspect of the invention, while the shutter is made from metal, the vacuum arc deposition apparatus may further include a resistor connected between the shutter and the anode or the vacuum chamber also serving as an anode, an ampere meter for measuring a current flowing into the shutter via the resistor, and a shut-down control unit for making a shut-down control for shutting down an output of the arc power supply when the current measured by the ampere meter exceeds a predetermined reference value.  
           [0030]    With such a configuration, the resistor can prevent the shutter from floating electrically, while the resistor can reduce the occurrence of abnormal discharge between the shutter and the cathode. This is due to the resistor put between the positive electrode of the arc power supply (in other words, the anode or the vacuum chamber also serving as the anode) and the shutter. That is, when discharge is about to occur from the cathode toward the shutter, the current flowing into the resistor increases so that a voltage drop in the resistor increases to block the abnormal discharge. In addition, when the current flowing into the shutter exceeds a predetermined reference value for some reason, the output of the arc power supply can be shut down automatically by the shut-down control unit. Thus, abnormal discharge in the shutter can be prevented more surely. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0031]    [0031]FIG. 1 is a sectional view showing an embodiment of vacuum arc deposition apparatus according to the invention;  
         [0032]    [0032]FIG. 2 is a front view showing an example of the vicinity of cathodes of an arc evaporation source in the vacuum arc deposition apparatus according to the invention, viewed in the arrow P direction in FIG. 1;  
         [0033]    [0033]FIG. 3 is a front view showing another example of the vicinity of cathodes of an arc evaporation source in the vacuum arc deposition apparatus according to the invention, viewed in the arrow P direction in FIG. 1;  
         [0034]    [0034]FIG. 4 is a sectional view showing an example of vacuum arc deposition apparatus in the related art; and  
         [0035]    [0035]FIG. 5 is a front view showing another example of the vicinity of cathodes of an arc evaporation source in the vacuum arc deposition apparatus in the related art, viewed in the arrow P direction in FIG. 4. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0036]    [0036]FIG. 1 is a sectional view showing an embodiment of vacuum arc deposition apparatus according to the invention. FIG. 2 is a front view showing an example of the vicinity of cathodes of an arc evaporation source in the vacuum arc deposition apparatus according to the invention, viewed in the arrow P direction in FIG. 1. Parts the same as or corresponding to those in the related-art example shown in FIGS. 4 and 5 are denoted by the same reference numerals correspondingly, and different points from the related-art example will be chiefly described below.  
         [0037]    A vacuum arc deposition apparatus of the present invention has the following arc evaporation source  10   a  instead of the arc evaporation source  10  in the related art. The number of arc evaporation sources  10   a  may be either one or plural as described previously.  
         [0038]    In this embodiment, the arc evaporation source  11   a  has a cathode holder  12  as described above, a plurality of cathodes  14  attached to the cathode holder  12 , a trigger electrode  20  as described above, and a trigger drive unit  22   a  for driving the trigger electrode  20  mechanically instead of the trigger drive unit  22  in the related art.  
         [0039]    In this embodiment, as is understood well with reference to FIG. 2, two cathodes  14  are arranged adjacently to each other and attached to the cathode holder  12 . Each cathode  14  is electrically connected to a negative electrode of an arc power supply  28  through the cathode holder  12 .  
         [0040]    The plurality of cathodes  14  are preferably made to have the same shape and the same dimensions as one another. Thus, the manufacturing cost of the cathodes  14  can be reduced. It also becomes easy to attach the cathodes  14  to the cathode holder  12 . Further, the structure of a shutter  32  which will be described later becomes simple. In this embodiment, the plurality of cathodes  14  have the same columnar shape and the same dimensions as one another by way of example.  
         [0041]    In this embodiment, the trigger drive unit  22   a  perform two operations. One of the operations is to rotate the trigger electrode  20  through a shaft  24  reciprocatively as shown by the arrow C, so as to move the trigger electrode  20  to left and right and position the trigger electrode  20  in front of a desired one of the plurality (two in this embodiment) of the cathodes  14  (that is, in front of the position where a cathode material  16  should be evaporated). The other of the operations is to move the trigger electrode  20  forward/backward as shown by the arrow B in the position in front of the desired cathode  14 , so as to connect/disconnect the trigger electrode  20  to/from the cathode  14 . The cathode  14  where the trigger electrode  20  is positioned can be used.  
         [0042]    The arc evaporation source  10   a  further includes a shutter  32  and a shutter drive unit  34 . The shutter  32  can cover all the cathodes  14  except the desired cathode for the plurality (two in this embodiment) of cathodes  14 . The shutter drive unit  34  rotates a shaft  36  reciprocatively as shown by the arrow D to thereby move the shutter  32  to left and right through the shaft  36 , an arm  37  and a feedthrough  38 , so as to change over the cathode  14  not covered with the shutter  32  (in other words, opened or used, the same meaning will be established below) alternatively. The feedthrough  38  has a vacuum seal function and an electrical insulating function in this embodiment.  
         [0043]    The shutter  32  and the trigger electrode  20  are disposed not to interfere with each other even if they are rotated simultaneously. For example, in this embodiment, the shaft.  24  of the trigger electrode  20  and the shaft  36  of the shutter  32  are disposed in positions opposite to each other with the cathode holder  12  interposed therebetween, and the trigger electrode  20  is positioned outside the shutter  32 .  
         [0044]    In this embodiment, the shutter  32  has a disc-like shape a little larger than each cathode  14 . When the position of the shutter  32  is changed over as shown by the arrow D, the front of a desired one of the two cathodes  14  can be covered with the shutter  32 .  
         [0045]    The vacuum arc deposition apparatus further has a changeover control unit  40 . The changeover control unit  40  makes a changeover control to control the shutter drive unit  34  and the trigger drive unit  22   a  so as to change over a cathode  14  not covered with the shutter  32  alternatively while, for example, synchronously therewith, positioning the trigger electrode  20  in front of the cathode  14  not covered with the shutter  32 . For example, in this embodiment, the changeover control unit  40  performs a changeover control as follows. That is, when one (right) cathode  14  is covered with the shutter  32 , the trigger electrode  20  is positioned to the other (left) cathode  14  side as shown by the solid line in FIG. 2. On the other hand, when the other (left) cathode  14  is covered with the shutter  32 , the trigger electrode  20  is positioned to the one (right) cathode  14  side as shown by the chain double-dashed line in FIG. 2.  
         [0046]    When such changeover operations were carried out in the trigger drive unit  22   a  and the shutter drive unit  34  independently of each other, there might occur an abnormal behavior to bring the trigger electrode  20  into contact with the cathode  14  covered with the shutter  32 . However, such an abnormal behavior can be prevented by the changeover control unit  40 .  
         [0047]    The angles with which the shutter  32  and the trigger electrode  20  should be rotated in the aforementioned changeover control depend on the structure such as the distance between the two cathodes  14 , the distance between the shaft  36  of the shutter  32  and the two cathodes  14 , and the distance between the shaft  24  of the trigger electrode  20  and the two cathodes  14 . The angles may be set in advance, for example, in the changeover control unit  40 .  
         [0048]    The number of cathodes  14  attached to the cathode holder  12  may be larger than two. FIG. 3 shows an example in which the number of cathodes  14  is four. In this example, the four cathodes  14  are disposed on the same circumference.  
         [0049]    In this example, the shutter  32  is formed into a disc-like shape to cover the four cathodes  14  as a whole, and designed to have an opening portion  33  partially. The opening portion  33  is a little larger than each cathode  14  so as to expose only one cathode  14  therefrom. With such a structure, the shutter  32  can cover the fronts of all the cathodes  14  except a desired cathode.  
         [0050]    In order avoid the interference of the shutter  32  and the trigger electrode  20  with each other, in this example, the shaft  24  for driving the trigger electrode  20  and the shaft  36  shaped in a hollow shape for driving the shutter  32  are disposed coaxially with each other so that the former is located inside the latter while the shafts  24  and  36  are positioned in the center of the circle with which the four cathodes  14  are disposed. The trigger electrode  20  is positioned outside the shutter  32  for the cathode holder  12 , that is, a surface of the cathode  14  from which the cathode material  16  is evaporated. The shafts  24  and  36  are electrically insulated from each other.  
         [0051]    The trigger drive unit  22   a  is coupled with the shaft  24  while the shutter drive unit  34  is coupled with the shaft  36 . The trigger drive unit  22   a  and the shutter drive unit  34  can be disposed not to interfere with each other mechanically by a known technique.  
         [0052]    The shutter  32  is rotated by a predetermined angle (90 degrees in this example) at one time by the shutter drive unit  34  as shown by the arrow D while the trigger electrode  20  is rotated by a predetermined angle (90 degrees in this example) at one time by the trigger drive unit  22   a  as shown by the arrow C. Then, these rotations are controlled by the changeover control unit  40  in the same manner as in the example of FIG. 2. That is, the changeover control unit  40  performs a changeover control to change over a cathode  14  not to-be covered with the shutter  32  (that is, to be exposed from the opening portion  33 ) alternatively while positioning the trigger electrode  20  in front of the cathode  14  exposed from the opening portion  33 .  
         [0053]    The structure in FIG. 3 can be also applied to the case where the number of cathodes  14  is a plural number other than four. For example, it can be applied to the case where the number of cathodes  14  is two, three, five, or the like. When the number of cathodes  14  is  n  ( n  is an integer not smaller than 2), the plurality of cathodes  14  may be disposed at an equal interval of 360/n degrees on the same circumference while the shutter  32  and the trigger electrode  20  are rotated by the angle of 360/n degrees at one time under the control of the changeover control unit  40 .  
         [0054]    According to the vacuum arc deposition apparatus, one arc evaporation source  10   a  has a plurality of cathodes  14 , and the changeover control unit  40  can change over a cathode  14  not covered with the shutter  32  alternatively while positioning the trigger electrode  20  in front of the cathode  14  not covered with the shutter  32 . Thus, the plurality of cathodes  14  can be used while being changed over alternatively in the condition that the vacuum chamber  2  is not opened to the atmosphere. It is therefore possible to perform the film deposition operation on the substrate:  4  continuously by use of the plurality of cathodes  14 .  
         [0055]    On that occasion, in this vacuum arc deposition apparatus, not only is the position of the trigger electrode  20  changed over to thereby change over the cathode  14  to be used, but all the cathodes  14  except the cathode  14  to be used are also covered with the shutter  32 . Accordingly, (a) the cathode material  16  evaporated from the cathode  14  in use can be prevented from adhering to the surface of any other unused cathode  14  by the shutter  32 . Further, (b) arc discharge in the cathode  14  in use can be prevented from shifting to another unused cathode  14  to thereby cause undesired arc discharge by the shutter  32 .  
         [0056]    The kinds (materials) of the plurality of cathodes  14  provided in the single arc evaporation source  10   a  may be made the same as one another or different from one another, or cathodes  14  of the same kind and of different kinds may be mixed in the single arc evaporation source  10   a.  For example, when the number of cathodes  14  is two, the both may be of the same kind A, or of different kinds in such a manner that one is of the kind A while the other is of another kind B. When the number of cathodes  14  is three, all the three may be of the same kind A, or the three may be of different kinds A, B and C from one another. Alternatively, for example, two of the same kind A and one of another kind B may be mixed.  
         [0057]    When the kinds of cathodes are made the same as one another, the film deposition time on the substrate  4  can be prolonged in accordance with the number of cathodes  14  in comparison with that when the number of cathodes  14  is one. For example, when the cathodes  14  have the same dimensions, the film deposition time can be prolonged as many times as the number of cathodes  14 .  
         [0058]    When the kinds of cathodes are made different from one another, a wide variety of films can be formed on the substrate  4  in accordance with the number of cathodes  14 . Thus, the degree of freedom to form a laminated film can be enhanced in comparison with when the number of cathodes  14  is one. In this case, the effect in the paragraph (a) due to the fact that all the cathodes  14  except the cathode  14  in use are covered with the shutter  32  is particularly effective. That is, if there were, among the unused cathodes  14 , a cathode  14  not covered with the shutter  32 , the cathode material  16  evaporated from the cathode  14  in use (which will be referred to as “first cathode”) would adhere to the surface of the cathode  14  not covered with the shutter  32  (which cathode will be referred to as “second cathode”). When a film is next formed with the second cathode  14 , the cathode material  16  adhering to the second cathode  14  would be evaporated so that a film having a composition different from an intended composition would be formed on the substrate  4  for a while. According to this vacuum arc deposition apparatus, such a problem can be prevented.  
         [0059]    When cathodes  14  of the same kind and of different kinds are mixed, not only is it possible to prolong the film deposition time but it is also possible to enhance the degree of freedom to form a laminated film.  
         [0060]    For example, the changeover control unit  40  performs the changeover control in response to a changeover instruction given from the outside (for example, an operator or the like). More specifically, an operator may decide the changeover time and give a changeover instruction to the changeover control unit  40  so that the changeover control unit  40  can carry out the changeover control in response to the changeover instruction. Alternatively, the changeover control may be carried out automatically in the following manner.  
         [0061]    That is, as shown in the embodiment of FIG. 1, an arc current integrator  42  may be further provided for integrating an arc current I A  flowing into the arc power supply  28  via the cathode holder  12  during current-carrying time  t  so as to obtain an arc current amount Q (=I A ·t) Then, the changeover control unit  40  is designed to carry out the changeover control whenever the arc current amount Q obtained by the arc current integrator  42  exceeds a predetermined reference value R 1 . The arc current amount Q obtained by the arc current integrator  42  is supplied to .the changeover control unit  40 . In addition, the reference value R 1  is set in the changeover control unit  40 .  
         [0062]    The arc current amount Q obtained by the arc current integrator  42  is proportional to the degree of consumption of the cathode  14  which is in use at that time. Accordingly, with the configuration, a cathode  14  to be used can be changed over automatically whenever the consumption of the cathode  14  in use reaches a predetermined quantity of consumption.  
         [0063]    It is preferable that the arc current amount Q obtained by the arc current integrator  42  is, for example, reset to zero whenever the cathode  14  to be used is changed over. In such a manner, the reference value R 1  can be set so easily that the control becomes easy. For example, when the plurality of cathodes  14  are of the same kind, it will go well if one reference value R 1  is set. Thus, the control becomes very easy.  
         [0064]    In spite of the same arc current amount Q, the quantity of consumption of one kind of cathode  14  may differ from that of another kind of cathode  14 . Therefore, when different kinds of cathodes  14  are mixed in the plurality of cathodes  14 , the reference value R 1  may be changed over in accordance with the kind of the cathode  14  located in position for use. In such a manner, even if different kinds of cathodes  14  are mixed, the cathode  14  to be used can be changed over automatically whenever the consumption of any cathode  14  in use reaches a substantially fixed quantity of consumption.  
         [0065]    For example, the shutter  32  is made from metal. In that case, as shown in the vacuum arc deposition apparatus according to this embodiment, it is preferable that the shutter  32  is connected to the anode or the vacuum chamber  2  also serving as an anode, in other words, to the positive side of the arc power supply  28  through a resistor  44 . The resister  44  is electrically connected to the shutter  32  via the conductive shaft  36  in this embodiment.  
         [0066]    With such a configuration, the resistor  44  can prevent the shutter  32  from floating electrically, while the resistor  44  can reduce the occurrence of abnormal discharge between the shutter  32  and the cathode  14 . This is due to the resistor  44  put between the positive electrode of the arc power supply  28  (in other words, the anode or the vacuum chamber  2  also serving as the anode) and the shutter  32 . That is, when discharge is about to occur from the cathode  14  toward the shutter  32 , the current flowing into the resistor  44  increases so that a voltage drop in the resistor  44  increases to block the abnormal discharge.  
         [0067]    Further, as in this embodiment, there may be provided an ampere meter  46  and a shut-down control unit  48 . The ampere meter  46  measures a current I s  flowing into the shutter  32  via the resistor  44 . The shut-down control unit  48  makes a shut-down control for shutting down the output of the arc power supply  28  when the current I s  measured by the ampere meter  46  exceeds a predetermined reference value R 2 .  
         [0068]    The reference value R 2  is set in the shut-down control unit  48 . When the current I s  exceeds the reference value R 2 , shut-down signal S is supplied from the shut-down control unit  48  to the arc power supply  28 . The arc power supply  28  shuts down its output in response to the shut-down signal S.  
         [0069]    During arc discharge produced in one cathode  14 , a slight (for example, about 1 or 2 A) current I s  may flow into the shutter  32  due to the influence of the arc discharge even at normal time. Thus, the reference value R 2  may be preferably set at a value (for example, about 10 A) larger than the current I s  to some extent.  
         [0070]    With such a configuration, when the current I s  flowing into the shutter  32  exceeds the predetermined reference value R 2  for some reason, the output of the arc power supply  28  can be shut down automatically by the shut-down control unit  48 . Thus, abnormal discharge in the shutter  32  can be prevented more surely.  
         [0071]    With the configuration as described above, the invention can obtain the following effects.  
         [0072]    According to the invention, a plurality of cathodes in an arc evaporation source can be used while being changed over in the condition that a vacuum chamber is not opened to the atmosphere. It is therefore possible to prolong the film deposition time on a substrate or to enhance the degree of freedom to form a laminated film.  
         [0073]    In addition, according to the invention, not only is the position of a trigger electrode changed over to change over a cathode to be used, but all the cathodes except the cathode to be used are also covered with a shutter. Accordingly, the cathode material evaporated from the cathode in use can be prevented from adhering to the surface of any other unused cathode by the shutter. Further, arc discharge in the cathode in use can be prevented from shifting to another unused cathode to thereby cause undesired arc discharge by the shutter.  
         [0074]    According to the invention, an arc current integrator and a changeover control unit are provided as described above. Thus, there is another effect that a cathode to be used can be changed over automatically whenever the consumption of the cathode in use reaches a predetermined quantity of consumption.  
         [0075]    According to the invention, a resistor, an ampere meter and a shut-down control unit are provided as described above. Thus, there is another effect as follows. That is, it is possible to prevent the shutter from floating electrically, while it is possible to reduce the occurrence of abnormal discharge between the shutter and the cathode. In addition, when the current flowing into the shutter exceeds a predetermined reference value for some reason, the output of an arc power supply can be shut down automatically by the shut-down control unit. Thus, abnormal discharge in the shutter can be prevented more surely.