Patent Publication Number: US-2022223390-A1

Title: Film formation apparatus and film formation method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Japanese Patent Application No. 2021-004131 filed on Jan. 14, 2021, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a film formation apparatus and a film formation method. 
     BACKGROUND 
     A film formation apparatus disclosed in Japanese Laid-open Patent Publication No. 2019-004075 includes a processing container, and a stage is installed in the processing container. The stage includes an electrostatic chuck on which a wafer is mounted. In addition, a plurality of (three or more) targets are installed above the stage. The plurality of targets have metallic materials which are different from one another. Also, each of the plurality of targets is held by a holder made of a metal. The holder is supported on a ceiling portion of the processing container via an insulating member. A power supply is connected to each of the plurality of targets via the holder. The power supply applies a negative direct current (DC) voltage to each of the plurality of targets. Further, a plurality of magnets are disposed outside the processing container so as to face the corresponding targets. The film formation apparatus includes a plurality of scanning mechanisms for operating the plurality of magnets respectively. 
     SUMMARY 
     The technique according to the present disclosure makes it possible to mount a wider variety of targets in a film formation apparatus which forms a film on a substrate by sputtering without changing a size of a cathode and without increasing a size of the apparatus. 
     In accordance with an aspect of the present disclosure, there is provided a film formation apparatus which forms a film on a substrate by sputtering. The apparatus comprises: a substrate holder configured to hold the substrate; and a plurality of cathodes configured to hold targets that emit sputtered particles, and connected to a power supply. At least one of the plurality of cathodes holds the targets of a plurality of types. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a longitudinal cross-sectional view illustrating an outline of a configuration of a film formation apparatus according to an embodiment. 
         FIG. 2  is a schematic bottom view of a ceiling portion of a processing container. 
         FIG. 3  is a diagram for describing a configuration around a first cathode. 
         FIG. 4  is a diagram for describing a configuration around a second cathode. 
         FIG. 5  is a schematic bottom view of a first shutter. 
         FIG. 6  is a schematic bottom view of a second shutter. 
         FIG. 7  is a diagram illustrating a state in which one target is selectively exposed by the first shutter and the second shutter. 
         FIG. 8  is a diagram illustrating the state in which one target is selectively exposed by the first shutter and the second shutter. 
         FIG. 9  is a diagram illustrating the state in which one target is selectively exposed by the first shutter and the second shutter. 
         FIG. 10  is a diagram illustrating another example of the cathode. 
     
    
    
     DETAILED DESCRIPTION 
     In a manufacturing process of a semiconductor device or the like, a film forming process for forming a desired film such as a metal film is performed on a substrate such as a semiconductor wafer (hereinafter, referred to as a “wafer”). This film forming process is performed by, for example, sputtering. 
     The film formation apparatus for forming a film by sputtering includes a substrate holder which holds the substrate, and a cathode which holds a target that emits sputtered particles so that it faces the substrate holder, and is connected to a power supply. The cathode is supported, for example, on a ceiling portion of a processing container in which the substrate holder is installed. 
     A plurality of targets may be mounted in the film formation apparatus. For example, when a multilayer film having different compositions between layers is formed by one film formation apparatus, the plurality of targets are mounted. When the plurality of targets are mounted, the targets are held on different cathodes respectively (refer to Japanese Laid-open Patent Publication No. 2019-004075). 
     Further, in recent years, mounting more types of targets in the film formation apparatus may be required due to further multi-layering of the multilayer film and the like. However, when the number of cathodes is increased in order to increase the number of targets mounted in the film formation apparatus, the processing container which supports the cathodes becomes large, and the size of the film formation apparatus increases. When a design of the cathode is changed to make the cathode smaller, it is possible to suppress the increase in the size of the film formation apparatus when the number of cathodes is increased, but when the design of the cathode is changed, a state of emission of the sputtered particles into a processing space during sputtering changes, and thus it is necessary to review processing conditions, which is not preferable. 
     Therefore, the technology according to the present disclosure makes it possible to mount a wider variety of targets in the film formation apparatus which forms a film on the substrate by sputtering without changing a size of the cathode and without increasing a size of the apparatus. 
     Hereinafter, the film formation apparatus according to the present embodiment will be described with reference to the accompanying drawings. In the present specification and the drawings, elements having substantially the same functional configuration are designated by the same reference numerals, and duplicate description thereof will be omitted. 
     &lt;Film Formation Apparatus&gt; 
       FIG. 1  is a longitudinal cross-sectional view illustrating an outline of a configuration of the film formation apparatus  1  according to the present embodiment.  FIG. 2  is a schematic bottom view of a ceiling portion of the processing container  10  which will be described below.  FIG. 3  is a diagram for describing a configuration around a first cathode which will be described below.  FIG. 4  is a diagram for describing a configuration around a second cathode which will be described below.  FIG. 5  is a schematic bottom view of a first shutter which will be described below.  FIG. 6  is a schematic bottom view of a second shutter which will be described below.  FIGS. 7 to 9  are diagrams illustrating a state in which one target is selectively exposed by the first shutter and the second shutter. In  FIG. 1 , illustration of a shield which will be described below is omitted. 
     The film formation apparatus  1  in  FIG. 1  forms a film on a wafer W as the substrate by sputtering and, more specifically, forms a multilayer film on the wafer W by magnetron sputtering. The film formation apparatus  1  includes a processing container  10 . 
     The processing container  10  is configured to be depressurizable and accommodates the wafer W. The processing container  10  is made of, for example, aluminum and is connected to a ground potential. An exhaust device  11  for reducing a pressure in a space inside the processing container  10  is connected to a bottom portion of the processing container  10  via an adaptive pressure control (APC) valve  12 . Further, a loading and unloading port  13  of the wafer W is formed on a side wall of the processing container  10 , and a gate valve  13   a  for opening and closing the loading and unloading port  13  is installed at the loading and unloading port  13 . 
     A mounting table  14  as the substrate holder is installed in the processing container  10 . The wafer W is mounted on the mounting table  14 . The mounting table  14  has a base  14   a  and an electrostatic chuck  14   b.    
     The base  14   a  is formed in a disk shape using, for example, aluminum. A heater (not shown) for heating the wafer W is installed on the base  14   a . A cooling mechanism may be installed instead of the heater, or both the heater and the cooling mechanism may be installed. 
     The electrostatic chuck  14   b  includes a dielectric film and an electrode installed as an inner layer of the dielectric film and is installed on the base  14   a . A direct current (DC) power supply  15  is connected to the electrode of the electrostatic chuck  14   b . The wafer W mounted on the electrostatic chuck  14   b  is attracted and held by the electrostatic chuck  14   b  by an electrostatic force generated by applying a DC voltage from the DC power supply  15  to the electrode. 
     The mounting table  14  is connected to a rotating and moving mechanism  16 . The rotating and moving mechanism  16  includes, for example, a support shaft  16   a  and a driving part  16   b.    
     The support shaft  16   a  extends in a vertical direction to pass through a bottom wall of the processing container  10 . A sealing member SL is installed between the support shaft  16   a  and the bottom wall of the processing container  10 . The sealing member SL is a member which seals a space between the bottom wall of the processing container  10  and the support shaft  16   a  so that the support shaft  16   a  can rotate and move up and down and is, for example, a magnetic fluid seal. An upper end of the support shaft  16   a  is connected to a center of a lower surface of the mounting table  14 , and a lower end thereof is connected to the driving part  16   b.    
     The driving part  16   b  has a driving source (for example, a motor or the like) which generates a driving force for rotating and moving the support shaft  16   a  up and down. As the support shaft  16   a  rotates around an axis AX thereof, the mounting table  14  rotates around the axis AX, and as the support shaft  16   a  moves up and down, the mounting table  14  moves up and down. 
     A plurality of cathodes  20   a , made of a metal such as copper, which hold the targets  20  are installed above the mounting table  14 , and in this example, four cathodes  20  are installed. Each of the cathodes  20   a  holds the target  20  at the front so that the target  20  is disposed in the processing container  10  and faces the mounting table  14 . Each of the cathodes  20   a  is installed on a ceiling portion of the processing container  10 . A through hole is formed at an installation position of each of the cathodes  20   a  in the processing container  10 . Further, an insulating member  10   a  is installed on an inner wall surface of the processing container  10  to surround the through hole. Each of the cathodes  20   a  is installed in the processing container  10  via the insulating member  10   a  to close the through hole. 
     Further, a power supply  21  is connected to each of the cathodes  20   a , and a negative DC voltage is applied from the power supply  21 . An AC voltage may be applied instead of the negative DC voltage. 
     Further, a magnet  22  is installed at a position on the rear side of each of the cathodes  20   a  and outside the processing container  10 . The magnet  22  is connected to a moving mechanism  23  and swings in a predetermined direction along a rear surface of the corresponding cathode  20   a  by the moving mechanism  23 . The predetermined direction is, for example, a tangential direction of a circle centered on the axis AX at a center point of the corresponding cathode  20   a . The moving mechanism  23  includes a driving part (not shown) including a driving source (for example, a motor or the like) which generates a driving force for swinging the magnet  22 . 
     In this example, the number of cathodes  20   a  is four as described above. As shown in  FIG. 2 , the four cathodes  20   a  are arranged at equal intervals along a circumference centered on the axis AX. In the following, as described above, each of the cathodes  20   a  arranged at equal intervals along the circumference may be referred to as a first cathode  20   a   1 , a second cathode  20   a   2 , a third cathode  20   a   3 , and a fourth cathode  20   a   4  in a clockwise direction in order from the upper cathode in  FIG. 2 . 
     In the present embodiment, at least one of the four cathodes  20   a  can hold a plurality of types of targets  20  at the same time. 
     For example, as shown in  FIGS. 2 and 3 , one large target  20  is held on each of the first and third cathodes  20   a   1  and  20   a   3 , and as shown in  FIGS. 2 and 4 , two small targets  20  are held on each of the second and fourth cathodes  20   a   2  and  20   a   4  so as to be aligned in a swinging direction of the magnet  22 . 
     In the following, the target  20  held by the first cathode  20   a   1  may be referred to as a first target  20   1 , the target  20  of the two targets  20  held by the second cathode  20   a   2  on the positive side in a circumferential direction with respect to the axis AX when viewed from the mounting table  14  side may be referred to as a second target  20   2 , and the target  20  on the negative side in the same direction may be referred to as a third target  20   3 . Similarly, the target  20  held by the third cathode  20   a   3  may be referred to as a fourth target  20   4 , the target  20  of the two targets  20  held by the fourth cathode  20   a   4  on the positive side in the circumferential direction when viewed from the mounting table  14  side may be referred to as a fifth target  20   5 , and the target  20  on the negative side in the same direction may be referred to as a sixth target  20   6 . 
     The first to sixth targets  20   1  to  20   6  are made of different types of materials. 
     Further, a shield  24  is installed on the first cathode  20   a   1  in order to prevent contamination (cross-contamination) between the single target  20  held by the first cathode  20   a   1  and the targets  20  held by the other cathodes  20   a . The shield  24  is installed to cover an outer periphery of the target  20  held by the first cathode  20   a   1 . A similar shield  24  is installed on the third cathode  20   a   3 . 
     A shield  25  is installed on the second cathode  20   a   2  which holds the two targets  20  in order to prevent contamination between the two targets  20  held by the second cathode  20   a   2  and between the targets  20  held by the second cathode  20   a   2  and the targets  20  held by the other cathodes  20   a . The shield  25  is installed to cover the entire outer periphery of the plurality of targets  20  held by the second cathode  20   a   2  and to separate the two targets  20  held by the second cathode  20   a   2  from each other. A similar shield  25  is installed on the fourth cathode  20   a   4 . 
     The shields  24  and  25  can prevent the cathode  20   a  from being sputtered. Further, the shields  24  and  25  are formed of, for example, aluminum. 
     An end surface (a lower surface in the drawing) of each of the shields  24  and  25  on the mounting table  14  side and an end surface (a lower surface in the drawing) of the corresponding target  20  in an unused state on the mounting table  14  side are located (located below in the drawing) closer to the mounting table  14 . 
     A swing range of the magnet  22  with respect to each of the targets  20  differs depending on a size of the target  20 . For example, as shown by double-headed arrows in  FIGS. 3 and 4 , the swing range of the magnet  22  with respect to the small target  20  such as the second target  202  is smaller than the swing range of the magnet  22  with respect to the large target  20  such as the first target  201 , and specifically, it is about half. Thus, during film formation using the small target  20 , it is possible to suppress sputtering of unnecessary portions (for example, the shield  25  and other small target held on the same cathode). 
     Further, as shown in  FIG. 1 , a shutter  30  is installed between the cathode  20   a  and the mounting table  14 . Specifically, a first shutter  31  and a second shutter  32  are installed between the target  20  held by the cathode  20   a  and the mounting table  14 . Each of the first shutter  31  and the second shutter  32  has a shape along a conical surface with the axis AX as a central axis. The second shutter  32  is installed between the first shutter  31  and the mounting table  14 . 
     As shown in  FIG. 5 , a large opening  31   a  which is an opening having a size corresponding to the large target  20  held by the first and third cathodes  20   a   1  and  20   a   3  is formed in the first shutter  31 . Further, as shown in  FIG. 1 , one end of a rotating shaft  33  is connected to a central portion of the first shutter  31 . 
     As shown in  FIG. 6 , the second shutter  32  has a large opening  32   a  which is an opening having a size corresponding to the large target  20  held by each of the first and third cathodes  20   a   1  and  20   a   3 , and small openings  32   b  and  32   c  which are openings having a size corresponding to the small target  20  held by each of the second and fourth cathodes  20   a   2  and  20   a   4 . The small opening  32   b  is an opening for the target  20  on the positive side in the circumferential direction when viewed from the mounting table  14  side out of the two small targets  20  held by the second and fourth cathodes  20   a   2  and  20   a   4 . On the other hand, the small opening  32   c  is an opening for the target  20  on the negative side in the circumferential direction when viewed from the mounting table  14  side out of the two small targets  20  held by the second and fourth cathodes  20   a   2  and  20   a   4 . In the following, the small opening  32   b  and the small opening  32   c  may be referred to as a small opening  32   b  on the positive side and a small opening  32   c  on the negative side, respectively. 
     When the position of the large opening  32   a  is set to the 12 o&#39;clock position when viewed from the mounting table  14  side, for example, the position of the small opening  32   b  on the positive side is a position near 3 o&#39;clock, and the position of the small opening  32   c  on the negative side is a position near 6 o&#39;clock. 
     Openings similar to the large opening  32   a  and the small openings  32   b  and  32   c  may be formed in the first shutter  31 , and an opening similar to the large opening  31   a  may be formed in the second shutter  32 . 
     Further, as shown in  FIG. 1 , one end of the rotating shaft  34  is connected to a central portion of the first shutter  31  while the other end of the rotating shaft  34  is connected to a central portion of the second shutter  32 . 
     The central axis of the rotating shaft  33  and the central axis of the rotating shaft  34  are coaxially installed and substantially coincide with the axis AX. The rotating shaft  33  extends to the outside of the processing container  10 , and the other end thereof is connected to the rotating mechanism  35 . The rotating mechanism  35  is configured to rotate the rotating shaft  33  and the rotating shaft  34  independently from each other about the axis AX. The rotating mechanism  35  includes a driving part (not shown) including a driving source (for example, a motor or the like) which generates a driving force for rotating the rotating shaft  33  and the rotating shaft  34 . 
     The first shutter  31  rotates around the axis AX as the rotating shaft  33  rotates around the axis AX, and the second shutter  32  rotates around the axis AX as the rotating shaft  34  rotates around the axis AX. By the rotation of the first shutter  31  and the second shutter  32 , relative positions of the large opening  32   a , the small opening  32   b , the small opening  32   c , and the target  20  change. Thus, for example, among all the targets  20 , only one target  20  is selectively exposed to the mounting table  14  through the openings of the first shutter  31  and the second shutter  32 . 
     Specifically, for example, among all the targets  20 , only the first target  201  is exposed to the mounting table  14  through the large opening  31   a  and the large opening  32   a  as shown in  FIG. 7 , and the other targets  20  are shielded from the mounting table  14  by the first shutter  31  and the second shutter  32 . 
     Further, as shown in  FIG. 8 , among all the targets  20 , only the second target  202  is exposed to the mounting table  14  through the large opening  31   a  and the small opening  32   b  on the positive side, and the other targets  20  are shielded from the mounting table  14  by the first shutter  31  and the second shutter  32 . 
     Further, as shown in  FIG. 9 , among all the targets  20 , only the third target  20   3  is exposed to the mounting table  14  through the large opening  31   a  and the small opening  32   c  on the negative side, and the other targets  20  are shielded from the mounting table  14  by the first shutter  31  and the second shutter  32 . 
     Further, the film formation apparatus  1  includes a gas supply (not shown) which supplies a gas into the processing container  10 . The gas supply includes, for example, a gas source, a flow rate controller such as a mass flow controller, and a gas introduction part. The gas source stores a gas (for example, Ar gas) which is excited in the processing container  10 . The gas source is connected to the gas introduction part via the flow rate controller. The gas introduction part is a member which introduces a gas from the gas source into the processing container  10 . 
     When the gas is supplied from the gas supply, and electric power is supplied to the target  20  by the power supply  21 , the gas supplied into the processing container  10  is excited. Further, a magnetic field is generated in the vicinity of a front surface of the target  20  by the magnet  22 , and plasma is concentrated in the vicinity of the front surface of the target  20 . Then, when positive ions in the plasma collide with the target  20 , a substance constituting the target  20  is emitted from the target  20  as sputtered particles. Thus, a desired film is formed on the wafer W. 
     As shown in  FIG. 1 , the film formation apparatus  1  further includes a controller U. The controller U is configured of, for example, a computer equipped with a central processing unit (CPU), a memory, and the like, and includes a program storage (not shown). The program storage stores a program which controls the driving part  16   b , the driving part of the moving mechanism  23 , the driving part of the rotating mechanism  35 , and the like and realizes a film forming process described below in the film formation apparatus  1 . The program may be recorded on a storage medium which is readable by a computer and may be installed in the controller U from the storage medium. Further, a part or the whole of the program may be realized by dedicated hardware (a circuit board). 
     &lt;Film Forming Processing&gt; 
     Next, an example of the film forming process using the film formation apparatus  1  will be described. 
     (Loading) 
     First, under the control of the controller U, the wafer W is loaded into the processing container  10  adjusted to a desired pressure. Specifically, the gate valve  13   a  is opened, and a transport mechanism (not shown) in which the wafer W is held is inserted into the processing container  10  from a transport chamber (not shown) having a vacuum atmosphere adjacent to the processing container  10  via the loading and unloading port  13 . Then, the wafer W is transported above the mounting table  14 . Next, the wafer W is delivered onto raised support pins (not shown), then the transport mechanism is withdrawn from the processing container  10 , and the gate valve  13   a  is closed. At the same time, the support pins are lowered, and the wafer W is mounted on the mounting table  14  and is attracted and held by an electrostatic absorption force of the electrostatic chuck  14   b.    
     (Multilayer Film Formation) 
     Subsequently, a multilayer film is formed on the wafer W by magnetron sputtering. Specifically, a film formation using the first target  20   1 , a film formation using the second target  20   2 , a film formation using the third target  20   3 , a film formation using the fourth target  20   4 , a film formation using the fifth target  20   5 , and a film formation using the sixth target  20   6  are performed on the wafer W. The order of the film formation is arbitrary and predetermined. Further, at least one of the six types of film formations may be performed a plurality of times. 
     In the film formation using the first target  20   1 , by the rotation of the first shutter  31  and the second shutter  32  by the rotating mechanism  35 , only the first target  20   1  of all the targets  20  is selectively exposed to the mounting table  14  through the large opening  31   a  and the large opening  32   a . Then, the mounting table  14  is rotated by the rotating and moving mechanism  16 , and Ar gas, for example, is supplied from the gas supply (not shown) into the processing container  10 . Further, electric power is supplied from the power supply  21  to the first target  20   1 . At the same time, the moving mechanism  23  causes the magnet  22  to swing along the first cathode  20   a   1  in the predetermined direction described above. The Ar gas in the processing container  10  is ionized by the electric power from the power supply  21 , and electrons generated by the ionization drift by the magnetic field (that is, a leakage magnetic field) formed at the front of the first target  20   1  by the corresponding magnet  22  to generate high density plasma. The surface of the first target  20   1  is sputtered by the Ar ions generated in the plasma, and sputtered particles of a constituent material of the first target  20   1  are deposited on the wafer W to form a layer of the constituent material of the first target  20   1 . 
     In the film formation using the second target  20   2 , by the rotation of the first shutter  31  and the second shutter  32  by the rotating mechanism  35 , only the second target  20   2  of all the targets  20  is selectively exposed to the mounting table  14  via the large opening  31   a  and the small opening  32   b  on the positive side. Then, in this state, as in the case of the film formation using the first target  20   1 , the Ar gas is supplied into the processing container  10 , the power is supplied from the power supply  21 , the corresponding magnet  22  is swung, and the like. Thus, a layer of the constituent material of the second target  20   2  is formed. In the film formation using the small second target  20   2 , the swing range of the magnet  22  is set narrower than that in the film formation using the large first target  20   1 . 
     In the film formation using the third target  20   3 , by the rotation of the first shutter  31  and the second shutter  32  by the rotating mechanism  35 , only the third target  20   3  of all the targets  20  is selectively exposed to the mounting table  14  via the large opening  31   a  and the small opening  32   c  on the negative side. Then, in this state, as in the case of film formation using the second target  20   2 , the Ar gas is supplied into the processing container  10 , the power is supplied from the power supply  21 , and the corresponding magnet  22  is swung, and the like. Thus, a layer of the constituent material of the third target  20   3  is formed. 
     In the film formation using the fourth target  20   4 , by the rotation of the first shutter  31  and the second shutter  32  by the rotating mechanism  35 , only the fourth target  20   4  of all the targets  20  is selectively exposed to the mounting table  14  via the large opening  31   a  and the large opening  32   a . Then, in this state, as in the case of the film formation using the first target  20   1 , the Ar gas is supplied into the processing container  10 , the power is supplied from the power supply  21 , the corresponding magnet  22  is swung, and the like. Thus, a layer of the constituent material of the fourth target  20   4  is formed. 
     In the film formation using the fifth target  20   5 , by the rotation of the first shutter  31  and the second shutter  32  by the rotating mechanism  35 , only the fifth target  20   5  of all the targets  20  is selectively exposed to the mounting table  14  via the large opening  31   a  and the small opening  32   b  on the positive side. Then, in this state, as in the case of film formation using the second target  20   2 , the Ar gas is supplied into the processing container  10 , the power is supplied from the power supply  21 , and the corresponding magnet  22  is swung, and the like. Thus, a layer of the constituent material of the fifth target  20   5  is formed. 
     In the film formation using the sixth target  20   6 , by the rotation of the first shutter  31  and the second shutter  32  by the rotating mechanism  35 , only the sixth target  20   6  of all the targets  20  is selectively exposed to the mounting table  14  via the large opening  31   a  and the small opening  32   c  on the negative side. Then, in this state, as in the case of film formation using the second target  20   2 , the Ar gas is supplied into the processing container  10 , the power is supplied from the power supply  21 , and the corresponding magnet  22  is swung, and the like. Thus, a layer of the constituent material of the sixth target  20   6  is formed. 
     (Unloading) 
     After that, the wafer W is unloaded from the processing container  10 . Specifically, the wafer W is unloaded from the processing container  10  in a reverse operation of the loading operation. 
     Then, the process returns to the above-described loading operation, and the next wafer W to be filmed is processed in the same manner. 
     &lt;Effects&gt; 
     As described above, in the present embodiment, the film formation apparatus  1  includes a plurality of cathodes  20   a , and at least one cathode  20   a  of the plurality of cathodes  20   a  holds a plurality of types of targets  20 . Therefore, according to the present embodiment, various types of targets  20  can be simultaneously mounted in the film formation apparatus  1  without changing the size of the cathode  20   a  and without increasing the size of the film formation apparatus  1 . 
     Unlike the present embodiment, in the method of reducing the size of the cathode and increasing the number of cathodes, since the apparatus which forms a film by magnetron sputtering requires a magnet and a swing mechanism for the magnet for each of the cathodes, consequently, there is a limit to suppressing the increase in the size of the apparatus. 
     Further, the configuration of the film formation apparatus  1  according to the present embodiment can be applied to an existing film formation apparatus in which a plurality of cathodes  20   a  are included and a magnet  22  is installed for each of the cathodes  20   a  without changing the design of the cathode  20   a  and the magnet  22 . Therefore, in manufacturing the film formation apparatus  1  according to the present embodiment, the review of the film forming conditions and the like can be minimized. 
     Further, in the present embodiment, the plurality of targets  20  are installed to be arranged in the swing direction of the magnet  22  on the cathode  20   a  which holds the plurality of targets  20 . Unlike the present embodiment, when the plurality of targets  20  are installed to be arranged in a direction orthogonal to the swing direction of the magnet  22 , for example, it is necessary to change the design of the magnet  22  such that the plurality of magnets  22  are provided for one cathode  20   a . On the other hand, in the present embodiment, it is not necessary to change the design of the magnet  22  as described above. Further, the swing range of the magnet  22  can be adjusted without changing the design of the magnet  22  from the existing one, and it is possible to prevent unnecessary regions from being sputtered when the swing range of the magnet  22  with respect to the small target  20  is adjusted to be small. 
     Further, since the number of magnets  22  for one cathode  20   a  may be one, an increase in manufacturing cost can be suppressed. 
     Further, in the film formation apparatus  1  according to the present embodiment, since the target  20  for forming a thick layer may be large and the target  20  for forming a thin layer may be small, a difference in a lifetime between the targets  20  can be reduced. Therefore, the target for forming a thick layer and the target for forming a thin layer can be replaced at the same time without wasting the target for forming the thin layer. If the targets can be replaced at the same time in this way, a downtime (an operation stoppage period) of the apparatus due to the replacement can be reduced, which is preferable. 
     &lt;Another Example of Cathode&gt; 
       FIG. 10  is a diagram illustrating another example of the cathode. 
     In the above example, the number of the targets  20  held by the cathode  20   a  configured to be capable of holding the plurality of targets  20  is two, but it may be three or more as shown in the drawing. 
     Also in this example, the shield  25  is installed to cover the entire outer circumference of the plurality of targets  20  held by the cathode  20   a  and to separate the three targets  20  held by the cathode  20   a  from each other. 
     &lt;Other Examples of Shields&gt; 
     The first shield and the second shield are not limited to the above example. 
     For example, by making the number and the positions of the openings different from those in the examples of  FIGS. 5 and 6 , the rotating mechanism may be able to switch between (A) and (B) below by rotating the first shutter and the second shutter. 
     (A) One target  20  of all the targets held by the plurality of cathodes  20   a  is selectively exposed to the mounting table  14  through the openings of the first shutter and the second shutter. 
     (B) Two or more targets  20  of all the targets held by the plurality of cathodes  20   a  are selectively exposed to the mounting table  14  through the openings of the first shutter and the second shutter. 
     If the rotating mechanism can switch as described above, a layer of a single material can be formed on the wafer W by selectively exposing one target  20  to the mounting table  14  as in (A), and an alloy layer can be formed on the wafer W by selectively exposing two or more targets to the mounting table  14  as in (B). Therefore, a multilayer film including the alloy layer can be formed on the wafer W. 
     The embodiments disclosed at this time should be considered to be exemplary in all respects and not restrictive. The above embodiments may be omitted, replaced, or modified in various forms without departing from the scope of the appended claims and their gist.