Abstract:
To provide technology that can increase the productivity of an apparatus when magnetron sputtering is carried out using a target formed from magnetic material. The present disclosure is an apparatus provided with: a cylindrical body that is a target formed from magnetic material, disposed above a substrate; a rotating mechanism that rotates this cylindrical body around the axis of the cylindrical body; a magnet array provided inside a hollow part of the cylindrical body; and a power supply that applies voltage to the cylindrical body. Furthermore, the magnet array has a cross sectional profile, orthogonal to the axis of the cylindrical body. Thus, even if a target with a comparatively large thickness is used, reductions in the intensity of the magnetic field that leaks from the target can be suppressed, and local progress in erosion can be suppressed.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to a magnetron sputtering apparatus for forming a film on a substrate. 
       BACKGROUND 
       [0002]    Many magnetic materials are used in forming a magnetic random access memory (MRAM), which is expected to become the next generation memory or a hard disc drive. Most magnetic materials are typically formed as a thin film on a substrate by sputtering. The MRAM is a memory element, in which an insulating film is interposed between magnetic films made of a ferromagnetic material. Depending on whether magnetization directions of the magnetic films are the same or opposite, the memory element can be read when a change in the amount of current is detected at the insulating film. 
         [0003]    The sputtering is generally performed by a magnetron sputtering method using an apparatus having a circular or rectangular plate-shaped target  101  made of a magnetic material installed in a vacuum vessel, and a plurality of magnets  102  disposed on a back side of the target  101 , as shown in  FIG. 24 . In  FIG. 24 , reference numeral  103  designates a water cooling plate configured to cool the target  101 , and reference numeral  104  designates a support member of the magnets  102 . 
         [0004]    A leakage magnetic field from the magnet  102  causes a magnetic field to be generated along the bottom surface of the target  101 . Then, if a negative DC power or high frequency power, for example, is supplied to the target  101 , an electric field is generated perpendicular to the magnetic field and an inert gas such argon (Ar) gas introduced into the vacuum vessel becomes ionized. The perpendicular electric field then leads to a cycloidal motion of secondary electrons in plasma and the secondary electrons stay in the vicinity of the target  101 . Thus, the efficiency of inert gas ionization can be improved and high density plasma can be formed in the vicinity of the target. As a result, it is possible to increase the film forming rate of the magnetic film on the substrate and reduce the impact onto the substrate due to the entrapment of the secondary electrons in the vicinity of the target  101 . In addition, it is possible to obtain an effect, such as a reduction of infiltration of an inert gas into the magnetic film due to a decrease in pressure of the inert gas, i.e., reduction of infiltration of impurities into the film. 
         [0005]    However, since the target  101  is made of a magnetic material, the magnetic field generated from the magnets  102  is absorbed in the target  101 . The absorption amount depends on a saturated magnetic flux density or a magnetic permeability of the target  101 . That is, a magnetic field that is not totally absorbed by the target  101  but is leaked to generate the plasma. In general, the strength of a leakage magnetic field necessary to generate the plasma as above is equal to or greater than 200 gausses. 
         [0006]    However, in order to improve the productivity of the apparatus, it is necessary to reduce a frequency of exchange of the target  101 . For that reason, increasing a thickness of the target  101  was considered. However, if the target  101  has an increased thickness, the strength of the leakage magnetic field would decrease and thus, it is difficult to sufficiently increase the thickness. Techniques have been implemented such that a magnetic circuit configured by the magnets  102  or a volume of the magnets  102  obtains a high magnetic field strength, or those having a relatively high magnetic flux density, such as Nd—Fe—B (neodymium-iron-boron), have been used as a cathode magnet. However, in spite of such coping methods, it is difficult to sufficiently increase the thickness of the target  101 . For example, when the target  101  is formed with a Co35Fe65 alloy having a saturated magnetic flux density (Bs) of 2.4 T (a numerical value is represented in atomic percentage (at %)), an upper limit of its thickness is 5 mm or so. 
         [0007]    In addition, there is a problem in that an erosion rate is accelerated in the magnetic material target  101 .  FIG. 25  illustrates a profile of erosion  105  that is changed as the target  101  is sputtered. In  FIG. 25 , upper, intermediate and lower parts represent profiles of early, middle and late stages of the erosion  105 , respectively. The profiles of the target  101  are shown in the right side of the figure. The profiles of a target  106  made of a nonmagnetic material, as a comparative example, are shown in the left side. For the nonmagnetic material target  106 , since no change in a magnetic field leaking from the magnets  102  occurs throughout the early to late stages, the erosion  105  grows at a constant rate. 
         [0008]    However, for the magnetic material target  101 , if the erosion  105  is formed and the thickness of the target  101  is varied in its plane, the strength of the leakage magnetic field at a portion of the target  101  having a small thickness is increased more than the other portions of the target  101 . Thus, this makes a magnetic flux  107  concentrated at the small thickness portion. As a result, the small thickness portion is sputtered. Then, since this phenomenon becomes conspicuous as the sputtering proceeds, the erosion  105  exhibits a sharp gradient as shown in the profile at the late stage. That is, for the target  101 , since the erosion  105  grows largely at specific portions in the plane, sufficient utilization efficiency is not obtained as compared to the nonmagnetic material target  106 . As a result, a frequency of exchange of the target  101  is increased. 
         [0009]    Japanese Laid-open Patent Publication No. H06-17247 discloses a technique of forming a film on a substrate by sputtering with the substrate passing over a rotating cylindrical target. In addition, Japanese Laid-open Patent Publication No. H11-29866 also discloses a technique of sputtering performed on a substrate disposed to be fixed in the horizontal direction with respect to a cylindrical target. Further, Japanese Laid-open Patent Publication No. 2009-1912 discloses a technique of sputtering performed on a rotating wafer with a plate-shaped target inclined with respect to the wafer. However, since these documents do not take notice of the above problem generated due to the use of the magnetic material target, such a problem cannot be sufficiently solved. Moreover, Japanese Laid-open Patent Publication No. H06-17247 has a problem in that a process chamber is enlarged since a region for moving the substrate needs to be secured. 
       SUMMARY 
       [0010]    The present disclosure has been made in consideration of the above-mentioned points, and provides some embodiments of a magnetron sputtering apparatus capable of improving productivity of an apparatus when magnetron sputtering is performed using a target made of a magnetic material. 
         [0011]    In the present disclosure, there is provided a magnetron sputtering apparatus of forming a film on a substrate mounted on a rotatable mounting part inside a vacuum vessel by a magnetron sputtering method, the magnetron sputtering apparatus including: 
         [0012]    a cylindrical body that is a target made of a magnetic material and disposed above the substrate such that a central axis of the cylindrical body is offset from a central axis of the substrate in a direction along a surface of the substrate; 
         [0013]    a rotary mechanism configured to rotate the cylindrical body around the axis of the cylindrical body; 
         [0014]    a magnet arrangement assembly installed in a hollow portion of the cylindrical body; and a power supply part configured to apply a voltage to the cylindrical body, 
         [0015]    wherein a cross section of the magnet arrangement assembly perpendicular to the axis of the cylindrical body is shaped such that a central portion of the magnet arrangement assembly protrudes toward a peripheral surface of the cylindrical body more than both ends of the magnetic arrangement assembly in a circumferential direction of the cylindrical body. 
         [0016]    Specific embodiments of the present disclosure are, for example, as follows: 
         [0017]    (a) The magnetic material of the target comprises metal or alloy containing at least one of elements consisting of 3d transition metals of Fe, Co and Ni as a main component. 
         [0018]    (b) There is provided a moving mechanism configured to move the magnet arrangement assembly in an axial direction of the cylindrical body. 
         [0019]    (c) There is provided a moving mechanism configured to move the magnet arrangement assembly in the circumferential direction of the cylindrical body. 
         [0020]    (d) The cross section of the magnet arrangement assembly perpendicular to the axis of the cylindrical body is shaped such that a contour of a side of the magnet arrangement assembly facing the inner peripheral surface of the cylindrical body is formed in the shape of a curved line or a polygonal line along the inner peripheral surface of the cylindrical body from both the ends toward the central portion. 
         [0021]    (e) The cross section of the magnet arrangement assembly perpendicular to the axis of the cylindrical body is shaped such that a contour of a side of the magnet arrangement assembly facing the inner peripheral surface of the cylindrical body is formed in the shape of a step having multiple stages from both the ends toward the central portion. 
         [0022]    (f) The magnet arrangement assembly comprises a plurality of magnets, a distance between each magnet and the peripheral surface of the cylindrical body is 15 mm or less. 
         [0023]    (g) The magnet arrangement assembly comprises a first magnet, second magnets installed with the first magnet interposed therebetween such that a magnetic pole of sides of the second magnets facing the peripheral surface of the cylindrical body is different from a magnetic pole of a side of the first magnet facing the inner peripheral surface of the cylindrical body, and third magnets installed between the first magnet and the second magnets such that a magnetic pole direction of the third magnets faces from any one side of the first magnet and the second magnets toward the other side in order to enhance a magnetic field generated by the first and second magnets, and 
         [0024]    the third magnets protrude toward the peripheral surface of the cylindrical body more than the second magnets, and the first magnet protrudes toward the peripheral surface of the cylindrical body more than the third magnets. 
         [0025]    According to the present disclosure, a cylindrical body that is a target made of a magnetic material which is obliquely disposed with respect to a substrate and rotates around an axis is installed. In addition, a cross section of a magnet arrangement assembly perpendicular to the axis of the cylindrical body is shaped such that the central portion of the magnet arrangement assembly protrudes toward a peripheral surface of the cylindrical body more than both ends of the magnet arrangement assembly in the circumferential direction of the cylindrical body. Thus, even though the target has a large thickness, the strength of the magnetic field leaking from the magnet arrangement assembly to the outside of the cylindrical body can be restrained from being weakened. In addition, local erosion can also be restrained from being grown at the target. Accordingly, it is possible to improve the productivity of the apparatus by restraining an increase in the frequency of exchange of the target. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is a longitudinal sectional side view of a magnetron sputtering apparatus according to one embodiment of the present disclosure. 
           [0027]      FIG. 2  is a transversal sectional plan view of the magnetron sputtering apparatus. 
           [0028]      FIG. 3  is a perspective view showing magnets constituting a magnet arrangement assembly and a target. 
           [0029]      FIG. 4  is a longitudinal sectional side view of the magnet arrangement assembly and the target. 
           [0030]      FIG. 5  is a view illustrating the operation of a stage and the target when a film is formed. 
           [0031]      FIGS. 6 to 8  are views illustrating a state in which erosion grows in the target. 
           [0032]      FIG. 9  is a transversal sectional plan view of another magnetron sputtering apparatus. 
           [0033]      FIG. 10  is a view illustrating the operation of the magnet arrangement assembly of another magnetron sputtering apparatus. 
           [0034]      FIG. 11  is a transversal sectional plan view of still another magnetron sputtering apparatus. 
           [0035]      FIG. 12  is a side view showing another configuration example of the magnet arrangement assembly. 
           [0036]      FIGS. 13 to 15  are side views showing still another configuration example of the magnet arrangement assembly. 
           [0037]      FIG. 16  is a timing chart illustrating the operations of respective components of the magnetron sputtering apparatus. 
           [0038]      FIG. 17  is a view illustrating examples of an angle of magnets. 
           [0039]      FIG. 18  is a longitudinal sectional side view of a magnetron sputtering apparatus according to another embodiment of the present disclosure. 
           [0040]      FIG. 19  is a transversal sectional plan view of the magnetron sputtering apparatus. 
           [0041]      FIG. 20  is a timing chart illustrating the operations of respective components of the magnetron sputtering apparatus. 
           [0042]      FIGS. 21 to 22  are schematic views showing a result of an evaluation test. 
           [0043]      FIG. 23  is a graph showing results of evaluation tests. 
           [0044]      FIG. 24  is a view illustrating a configuration of a target of a conventional apparatus. 
           [0045]      FIG. 25  is a view illustrating states in which erosion grows in a magnetic material target and a nonmagnetic material target. 
       
    
    
     DETAILED DESCRIPTION 
     First Embodiment 
       [0046]    A magnetron sputtering apparatus  1  according to one embodiment of the present disclosure will be described with reference to the drawings.  FIG. 1  is a longitudinal sectional side view of the magnetron sputtering apparatus  1 .  FIG. 2  is a transversal sectional plan view of the magnetron sputtering apparatus  1 . Reference numeral  11  designates a vacuum vessel, which is made of, e.g., aluminum (Al), and is grounded. Reference numeral  12  designates a transfer port of a wafer W as a substrate, which is opened at a sidewall of the vacuum vessel  11  and is opened and closed by an opening/closing mechanism  13 . 
         [0047]    A circular stage  21  is installed inside the vacuum vessel  11 . A semiconductor wafer (hereinafter, simply referred to as a wafer) W that is a substrate is horizontally mounted on a surface of the stage  21 . The wafer W, for example, having a diameter of 150 mm to 450 mm, may be mounted on the stage  21 . One end of a shaft part  22 , which extends in the vertical direction, is connected to the central portion of the rear surface of the stage  21 . In order to enable a film thickness distribution to be finely controlled, the stage  21  is configured to have a lifting mechanism and a height of the stage  21  may be changed according to processing conditions. The other end of the shaft part  22  extends to the outside of the vacuum vessel  11  through an opening  14  formed at a bottom portion of the vacuum vessel  11  and is connected to a rotary driving mechanism  23 . The stage  21  is configured to be rotatable, e.g., at 0 rpm to 300 rpm, around the vertical axis by the rotary driving mechanism  23  through the shaft part  22 . A cylindrical rotary seal  24  is installed around the shaft part  22  so as to block a gap between the vacuum vessel  11  and the shaft part  22  from the outside of the vacuum vessel  11 . In  FIG. 1 , reference numeral  25  designates a bearing installed at the rotary seal  24 . 
         [0048]    A heater (not shown) is installed inside the stage  21 , thereby heating the wafer W at a predetermined temperature. In addition, the stage  21  is provided with push-up pins (not shown) configured to transfer the wafer W between the stage  21  and an external transfer mechanism (not shown) of the vacuum vessel  11 . 
         [0049]    An exhaust port  31  is opened at a lower portion of the vacuum vessel  11 . The exhaust port  31  is connected to one end of an exhaust pipe  32 , and the other end of the exhaust pipe  32  is connected to an exhaust pump  33 . In  FIG. 1 , reference numeral  34  designates an exhaust amount adjustment mechanism, which is installed through the exhaust pipe  32  to serve to adjust an internal pressure of the vacuum vessel  11 . A gas nozzle  35 , which is a plasma generation gas supply part, is installed at an upper side of the sidewall of the vacuum vessel  11 . The gas nozzle  35  is connected to a gas supply source  36  in which an inert gas such as Ar is reserved. In  FIG. 1 , reference numeral  37  designates a flow rate adjustment part including a mass flow controller, which controls the amount of the Ar gas supplied to the gas nozzle  35  from the gas supply source  36 . 
         [0050]    A target  41  that is a cylindrical body is installed along a horizontal axis inside the vacuum vessel  11 . The target  41  is obliquely disposed with respect to the wafer W such that an end R of the target  41  adjacent to the central axis of the wafer W in the length direction of the target  41  is above the wafer W. The sputtered particles from the target  41  are emitted according to the cosine law. That is, a number of the sputtered particles are emitted in proportion to the cosine value of an angle of the direction in which the sputtered particles are emitted with respect to a normal line of the surface of the target  41  from which the sputtered particles are emitted. In the case where the target  41  is obliquely disposed with respect to the wafer W as described above, the sputtered particles can be incident on the wafer W from a wider range of the target  41  as compared with a case in which the target  41  is disposed directly above the wafer W. Thus, it is possible to deposit the sputtered particles on the wafer W with high uniformity by appropriately setting an offset distance and a TS distance, which will be described later. In addition, when the target  41  is made of an alloy, it is possible to enhance alloy composition uniformity of the film formed on the wafer W. 
         [0051]    A distance L 1  (referred to as an offset distance) in the horizontal direction between the target  41  and the central axis of the wafer W on the stage  21  is set to fall within a range of, for example, 0 mm to 300 mm. If a height between the lower end of the target  41  and the surface the wafer W mounted on the stage  21  is a TS distance L 2 , the TS distance L 2  is set to fall within a range of, for example, 50 mm to 300 mm. The offset distance L 1  and the TS distance L 2  are determined according to a film thickness required for a magnetic film, a sputtering rate of the target  41  and the film quality. 
         [0052]    The target  41  is made of any one material of Co—Fe—B (cobalt-iron-boron) alloy, Co—Fe alloy, Fe, Ta (tantalum), Ru, Mg, IrMn, PtMn and the like, for example, for constituting a MRAM element. More specifically, the target  41  is made of a metal or alloy containing at least one of elements consisting of 3d transition metals of Fe, Co and Ni (nickel) as a main component. In the case where the element is processed to be contained in a metal or alloy as a main component, the element is not infiltrated into the metal or alloy as impurities. Instead, being contained in a metal or alloy as a main component refers to, for example, the case where the element in the metal or alloy is proportional to being equal or greater than 10% of the entirety of the target  41 . 
         [0053]    As shown in  FIG. 2 , a cylindrical rotating axis  42  having both of its ends extending from the inside of the vacuum vessel  11  to the outside is installed along with the target  41 . In the rotating axis  42 , the end positioned inside the vacuum vessel  11  has an expanded diameter to form a flange  43  and blocks one end of the target  41 . The rotating axis  42  is supported by the vacuum vessel  11  through an insulating member  44  configured to insulate the target  41  and the vacuum vessel  11  from each other. In addition, a cylindrical rotary seal  45  is installed in order to secure the air-tightness of the vacuum vessel  11  by blocking a gap (not shown) between the rotating axis  42  and the vacuum vessel  11  from the outside of the vacuum vessel  11 . In the  FIG. 2 , reference numeral  46  designates a bearing which is installed at the rotary seal  45 . The rotating axis  42  and the flange  43  are made of a conductive material and constitute an electrode  40  together with the target  41 . A negative DC voltage is applied to the electrode  40  by a power supply part  47 . However, a high frequency voltage may be applied instead of the DC voltage. 
         [0054]    A circular metal lid  48  is installed in order to block the other end of the target  41 . A rotating axis  49  extends from the central portion of the lid  48  toward the outside of the vacuum vessel  11  in the axial direction of the target  41 . In order to block a gap between the rotating axis  49  and the vacuum vessel  11 , a rotary seal  45  having a bearing  46  is installed in the same manner as the one end of the target  41 . In the same manner as the rotating axis  42 , the rotating axis  49  is supported by the vacuum vessel  11  through an insulating member  44 . The vacuum vessel  11  and the electrode  40  are insulated from each other by the insulating member  44 . Further, instead of the above configuration in which both the ends of the target  41  are respectively supported by the vacuum vessel  11  through the rotating axes  42  and  49 , the target  41  may be supported by the vacuum vessel  11  only through the rotating axis  42  without installing the rotating axis  49 . 
         [0055]    A belt  51  is wound around the rotating axis  42  and is driven by a motor  52  constituting the rotary mechanism. Thus, the target  41  is rotated around the rotating axis  42 . A magnet arrangement assembly  53  is installed at a hollow portion  50  of the target  41 . The magnet arrangement assembly  53  is provided with a support plate  54  extending in the axial direction and, for example, magnets  55 ,  55 ,  56 ,  57  and  57  supported on the support plate  54 . As viewed in the axial direction of the target  41 , the respective magnets  55  to  57  are installed in parallel with each other, as viewed from the side of the hollow portion  50 , in an obliquely downward direction facing toward the wafer W. Thus, the respective magnets  55  to  57  constitute a magnetic circuit. 
         [0056]      FIG. 3  shows a longitudinal sectional perspective view of the magnets  55  to  57 , and  FIG. 4  shows a longitudinal sectional side view of the magnets  55  to  57 . In  FIGS. 3 and 4 , reference numeral  58  designates leading end surfaces of the magnets. The respective magnets  55  to  57  are disposed to be spaced apart from each other as viewed from the side. In addition, the magnets  57  and  57  are disposed on the left and right of the magnet  56  such that the magnet  56  is interposed therebetween. In addition, magnets  55  and  55  are also disposed on the left and right of the magnets  57  and  57  such that the magnets  57  are interposed therebetween. The magnet  56 , as a first magnet, is configured to be rectangular in shape as viewed from the side. The magnets  55 , as second magnets, and the magnets  57 , as third magnets, are respectively configured in the shape of a trapezoid such that each leading end extending from the support plate  54  is an oblique side as viewed from the side. 
         [0057]    The magnets  56  and  55  are magnets configured to generate magnetic flux  60  outside the target  41 . A magnetic field direction (magnetic pole direction) of each of the magnets  56  and  55  is along the direction in which it extends from the support plate  54 . A side of the magnet  56  facing the target  41  is the N-pole, and sides of the magnets  55  facing the target  41  are the S-pole. The magnets  57  are installed in order to enhance the magnetic flux  60  between the magnets  56  and  55 . For this purpose, the magnetic pole direction of the magnets  57  is perpendicular to the magnetic pole direction of the magnets  56  and  55 . In addition, the sides of the magnets  57  facing the magnet  56  are the N-pole. In  FIG. 4 , the respective magnetic pole directions of the magnets  55  to  57  are represented by solid arrows. 
         [0058]    In addition, as the leading end surface  58  of each of the magnets  55  to  57  is configured to be further spaced apart from the support plate  54  toward the leading end surface  58  of the magnet  55  disposed at the central portion in the arrangement direction of the magnets  55  to  57 , the leading end surface  58  of each of the magnets  55  to  57  further protrudes from the support plate  54  toward a peripheral surface of the target  41 . That is, the leading end surface  58  of each of the magnets  55  to  57  appears to align with the inner periphery of the target  41  and is shaped in a polygonal line as viewed from the side. From another viewpoint, if a curved surface of the inner periphery of the target  41  is approximated to a straight line, each leading end surface  58  is installed to be parallel with the approximated straight line. 
         [0059]    As the respective magnets are configured as described above, by making the distance between the magnets  55  and  56  and the target  41  decrease, the magnetic flux  60  outside the target  41  is enhanced. Further, as the action of the magnets  57  can be made relatively large, the magnetic flux  60  can be more enhanced. That is, the leakage magnetic field from the target  41  can be increased. In  FIG. 4 , a distance d between the leading end surface  58  of the magnet  56  and the inner peripheral surface of the target  41  is set to fall within a range of, for example, 15 mm or less. A distance between the leading end surfaces  58  of the other magnets  55  and  57  and the inner peripheral surface of the target  41  is also set to fall within a range of, for example, 15 mm or less, in the same manner as above. 
         [0060]    Returning to  FIG. 2 , brackets  26  are connected to the support plate  54 . The brackets  26  are supported by being connected to a support rod  27  axially extending within the target  41  and the rotating axis  42 . An end  28  of the support rod  27  extends to the outside of the vacuum vessel  11  and is supported, for example, by a wall portion (not shown). 
         [0061]    The magnetron sputtering apparatus  1  is provided with a control unit  6 . The control unit  6  includes a program for transmitting a control signal to each component of the magnetron sputtering apparatus  1 . This program transmits the control signal configured to control the operation of each component of the magnetron sputtering apparatus  1  so as to perform the film formation processing described later. Specifically, the operation of supplying power to the electrode  40  from the power supply part  47 , the operation of adjusting a flow rate of Ar gas by the flow rate adjustment part  37 , the operation of adjusting an internal pressure of the vacuum vessel  11  by the exhaust amount adjustment mechanism  34 , the operation of rotating the stage  21  by the rotary driving mechanism  23 , the operation of rotating the target  41  by the motor  52 , and the like are controlled by the control signals. The program is stored in a storage medium, such as a hard disc, a compact disc, a magneto-optical disc, a memory card, or the like, and is installed to a computer from the storage medium. 
         [0062]    Subsequently, the operation of the above-described magnetron sputtering apparatus  1  will be described. The transfer port  12  of the vacuum vessel  11  is opened. The wafer W is loaded onto the stage  21  by cooperation between the external transfer mechanism (not shown) and push-up pins. Subsequently, the transfer port  12  is closed. The Ar gas is supplied into the vacuum vessel  11 , and the exhaust amount is controlled by the exhaust amount adjustment mechanism  34 . Thus, the interior of the vacuum vessel  11  is maintained at a predetermined pressure. 
         [0063]    Then, as shown by arrows in  FIG. 5 , while the stage  21  is rotated around the vertical axis, the target  41  is rotated around the axis by the motor  52 . A negative DC voltage is then applied from the power supply part  47  to the target  41 , such that an electric field is generated around the target  41 . Then, the Ar gas is ionized by the electric field to generate electrons. In the meantime, a magnetic field from the magnets  55  to  57 , which is not absorbed by the target  41  but leaks to the outside, causes a leakage magnetic field constituting the magnetic flux  60  to be generated between the magnets  55  to  57  as shown by dotted lines in  FIG. 5 . Thus, a horizontal magnetic field  61  is generated in the vicinity of the surface (sputtered surface) of the target  41  as shown in  FIG. 6 . 
         [0064]    In this way, the magnetic field and the electric field in the vicinity of the target  41  cause the electrons to be accelerated and drifted. Then, the electrons having sufficient energy caused by the acceleration also collide with the Ar gas and cause ionization thereof. Thus, this effect generates plasma and Ar ions  62  in the plasma are sputtered onto the target  41 . In addition, secondary electrons generated by the sputtering are captured by the horizontal magnetic field and also contribute to the ionization of the Ar gas. Accordingly, an electron density is increased to generate high density plasma. 
         [0065]      FIGS. 6 to 8  are schematic views showing a surface state of the target  41  varying over time. As shown in  FIGS. 6 and 7 , the target  41  is sputtered by the Ar ions  62  and sputtered particles  63  are emitted to form erosion  64 . Since the target  41  is rotated relative to the magnets  55  to  57 , a sputtered portion of the target  41  is displaced as shown in  FIGS. 7 and 8  and the erosion  64  is formed to be spread in the circumferential direction of the target  41 . Accordingly, the strength of the leakage magnetic field is prevented from being rapidly increased. As a result, it is possible to restrain the erosion  64  from locally growing toward the thickness direction of the target  41 . 
         [0066]    The sputtering of the target  41  more rapidly proceeds at a portion in which a horizontal component of the leakage magnetic field with respect to the surface of the target  41  is stronger. Thus, a large amount of the sputtered particles  63  are emitted from the corresponding portion. The emitted sputtered particles  63  are incident on and attached to the surface of the rotating wafer W. By offsetting a position at which the sputtered particles  63  are incident in the circumferential direction of the wafer W, the sputtered particles are supplied to the entire circumferential direction of the wafer W. Thus, a magnetic film is formed. When the power supply part  47  is turned on and a predetermined time then passes, the power is turned off to stop the generation of plasma and the supply of the Ar gas. Then, the vacuum vessel  11  is exhausted with a predetermined exhaust amount. The wafer W is unloaded from the vacuum vessel  11  in the reverse operation to the loading. 
         [0067]    According to the magnetron sputtering apparatus  1 , the cylindrical target  41  made of a magnetic material is sputtered while rotating around the axis. The sputtered particles are incident on the wafer W rotating around the central axis to perform the forming of a film. With this configuration, since it is possible to restrain the erosion of the target  41  from locally growing, utilization efficiency of the target  41  is improved. In addition, as viewed in the axial direction of the target  41 , the magnet arrangement assembly  53  is configured such that the central portion of the target  41  protrudes out to be longer than either ends of the target  41  toward the inner peripheral surface of the target  41 . With this configuration, since the strength of the magnetic field leaking from the target  41  can be made large, it is possible to relatively increase the thickness of the target  41 . Therefore, since the number of the wafers W which can be processed by one target  41  is increased, a frequency of exchange of the target  41  is restrained. As a result, the productivity of the magnetron sputtering apparatus  1  can be improved. 
         [0068]    In the first embodiment, as the target  41  is obliquely disposed with respect to the wafer W and the wafer W is rotated when a film is formed, the in-plane film thickness uniformity of the wafer W is promoted. Thereafter, examples of the apparatus for further improving the film thickness uniformity will be described.  FIG. 9  shows a first modification of the magnetron sputtering apparatus  1 . The first modification is different from the above embodiment in that an end of the support rod  27  is connected to a rotary mechanism  71 . In addition, the magnet arrangement assembly  53  may be rotated around the axis of the target  41 , independent from the target  41 . With this configuration, as shown in  FIG. 10 , a slope of the magnet arrangement assembly  53  may be changed. 
         [0069]    For example, according to processing conditions such as an internal pressure of the vacuum vessel  11 , a material of the target  41  and a voltage applied to the target  41  when a film is formed, an angle of the sputtered particles incident on the wafer W from the target  41  is changed. Accordingly, appropriate slopes of the magnets  55  to  57  corresponding to a variety of combinations of the pressures, the materials and the applied voltages are acquired in advance by experiments. Then, the memory of the control unit  6  stores a database in which the pressures, the materials, the applied voltages and the slopes of the magnets  55  to  57  correspond to one another. Then, if before the wafer W is processed, a user sets the pressure, material and applied voltage for performing the processing at the control unit  6 , an appropriate slope of the magnets  55  to  57  is determined based on the database. Thereafter, the rotary mechanism  71  rotates the support rod  27 , the magnets  55  is fixed at the determined slope, and then, the wafer W is processed. 
         [0070]    In addition, when the rotary mechanism  71  is installed as described above, instead of the slope fixed during the processing of the wafer W, the slope of the magnets  55  to  57  may be continuously changed. For example, as shown in  FIG. 10 , the slope of the magnets  55  is changed such that a state represented by a solid line in which the magnets  55  to  57  are horizontal and a state represented by a chain line in which the magnets  55  to  57  face downward are alternately repeated. In addition, the memory of the control unit  6  stores data of moving speeds at respective points of a moving route of the magnets  55  to  57  which correspond to the respective processing conditions, instead of the slopes of the magnets  55  to  57 . Further, if the user sets processing conditions, the magnets  55  to  57  move along the respective points of the moving route at a moving speed corresponding to the processing conditions. In this way, a film thickness distribution of the wafer W can be controlled. 
         [0071]    Furthermore,  FIG. 11  shows a second modification of the magnetron sputtering apparatus  1 . In this second modification, the magnet arrangement assembly  53  is sized so as to be moved back and forth inside the target  41  in its length direction. Further, the support rod  27  is advanced and retreated in its length direction by a moving mechanism  72 , such that a position of the magnet arrangement assembly  53  may be changed. In the same manner as in the first modification, according to processing conditions, the processing may be performed while the position of the magnet arrangement assembly  53  is fixed. Further, during the processing, the magnet arrangement assembly  53  may be continuously moved back and forth. In addition, moving speeds of the magnet arrangement assembly  53  at respective points along the movement route may be set according to the processing conditions. 
         [0072]    The configuration of the magnet arrangement assembly  53  is not limited to the above example. For example, as shown in  FIG. 12 , a contour of the leading end surface  58  of the magnets  55  and  56  may be shaped in a curve as viewed from the axial direction of the target  41 . Further, the number of magnets constituting the magnet arrangement assembly  53  may be arbitrary if the horizontal magnetic field can be generated with respect to the target  41  as described above. More specifically, two magnets may be disposed such that one magnet is interposed therebetween, the inner magnet and the outer magnets each face in a direction opposite to the target surface, and the number of the magnets need to be three or more as shown in  FIG. 12 . That is, the magnets  57  for enhancing a magnetic field may not be installed. Further, in the figures after  FIG. 12 , the magnetic pole directions of the respective magnets are represented by arrows in the same manner as  FIG. 4 . In addition, as shown in  FIG. 13 , from both ends of the magnet arrangement assembly  53  toward its central portion, the magnets may be configured to have a step shape having the respective leading end surfaces  58  formed to face the target  41 . 
         [0073]    In addition, as shown in  FIG. 14 , the magnets  55  to  57  may be configured to radially extend from the support plate  54 . In this example, as viewed from the side, a width of the magnet  57  is gradually increased toward the target  41 . The other magnets  55  and  56  are not limited to those each having a constant width in the extending direction in the same manner as the magnets  57 . Further, if a magnetic pole direction of the magnets  55  is vertical, in this example, a magnetic pole direction of each magnet  57  is set to be inclined from the magnets  55  toward the magnet  56 . In this way, the magnetic pole direction of the magnets  57  is not limited to being perpendicular to the magnetic pole direction of the magnets  55  and  56 . 
         [0074]    Further, while in each of the above examples, the support plate  54  is configured in the shape of a rectangle as viewed from the side, the present disclosure is not limited to such configuration.  FIG. 15  shows an example in which the support plate  54  is configured in the shape of a trapezoid as viewed from the side. The magnet  56  extends from the upper face of the trapezoid. The magnets  55  and  55  radially extend from the oblique sides of the trapezoid. The magnets  57  radially extend from angled portions defined by the upper face and the oblique sides. As the support plate  54  is configured as described above, the magnet can be manufactured to be shaped in a simple rectangular parallelepiped. Thus, the manufacturing cost of the magnet can be reduced. Furthermore, the magnets  55  and  56  having the same shape may be used. Accordingly, it is possible to reduce an effort of adjusting the shape of each magnet when the magnetron sputtering apparatus is manufactured. The surface of the support plate  54  on which the magnets  55  to  57  are installed is not limited to these examples and may be, for example, a curved surface. Also, the surface of the support plate  54  may be configured to have any shape according to the shape of the magnets  55  to  57 . 
         [0075]    However, in the examples shown in the respective figures, the magnets  57  may not be installed. In addition, the leading end surface  58  of the magnets  57  may be configured to be restrained from protruding toward the inner peripheral surface of the target  41  more than the leading end surface  58  of the magnet  56 . However, as already described above, in order to enhance the leakage magnetic field, it is effective that the magnets  57  are installed and the leading end surfaces  58  thereof are configured to protrude toward the peripheral surface more than the leading end surface  58  of the magnet  56 . 
         [0076]    An example of the processing performed using the magnetron sputtering apparatus  1  of the first modification illustrated in  FIGS. 9 and 10  will be described in more detail referring to a timing chart of  FIG. 16 . Four graphs  81  to  84  of this timing chart show the operations of the respective components of the magnetron sputtering apparatus  1  from before the processing of a wafer W until the processing of the wafer W is completed. The graph  81  indicates a timing at which power is applied to the target  41  by the power supply part  47 . The graph  82  indicates a rotational speed of the target  41 . The graph  83  indicates an angle of one magnet of the magnet arrangement assembly  53 . The graph  84  indicates an angle of the wafer W. 
         [0077]    The respective graphs  81  to  84  will be further described. The vertical axis of the graph  81  represents the power input to the target  41 . When the power input is turned on, a power of P watt is supplied to form a film on the wafer W. The magnitude of the power P is arbitrarily set. The vertical axis of the graph  82  represents the rotational speed of the target  41 . During the film formation processing, the target  41  is rotated at a constant speed V, for example. The same portion of the target  41  must not be sputtered continuously for a long time. Also, if the rotational speed of the target  41  is too high, the action of this rotation increases the number of particles scattered in a direction offset from the wafer W among the particles scattered from the target  41 . Therefore, in some embodiments, the rotational speed V is relatively low and specifically falls within a range of, for example, 0 rpm or more to 10 rpm or less. 
         [0078]    The vertical axis of the graph  83  represents the angle of the magnet. The angle of the magnet is, for example, an angle of a direction in which one magnet constituting the magnet arrangement assembly  53  extends from the support plate  54  with respect to the horizontal plane. The angle of the magnet at the initiation of the film formation processing is set to be T 1 , and the angle of the magnet at the termination of the film formation processing s set to be T 2 .  FIG. 17  shows an example of the angles T 1  and T 2 . In  FIG. 17 , reference numeral  80  designates the horizontal plane. The angle T 1  and a range of the angle T 1  to the angle T 2  are appropriately set according to a material of the target  41  or film forming conditions. The film forming conditions include a thickness of a film formed on the wafer W, the power input to the target  41 , and a processing pressure in the vacuum vessel  11 . If the moving speed of the magnet arrangement assembly  53  is too high, the magnetic field over the surface of the target  41  becomes unstable. Thus, in some embodiments, the moving speed of the magnet arrangement assembly  53  is relatively low. Specifically, the magnet arrangement assembly  53  moves, for example, at 1.5 degree/sec to 10 degree/sec. In addition, the moving direction of the magnet arrangement assembly  53  during the film formation processing may be the same as the rotational direction of the target  41  or the reverse direction thereof. 
         [0079]    The vertical axis of the graph  84  represents the angle of the wafer W. The angle of the wafer W is an angle of the wafer W mounted on the stage  21  which is set to 0 degree (equals to 360 degrees in one revolution) when a cutout (notch) formed at a side end of the wafer W is in a predetermined direction. In order to make a uniform film thickness distribution of a film formed while the wafer W rotates one revolution, in some embodiments, the wafer W is rotated a plurality of times, for example, eight times or more, during the film formation processing. However, if the rotational speed of the wafer W is too high, particles incident toward the wafer W bounce off due to the rotation of the wafer W. Thus, in some embodiments, the rotational speed is, for example, greater than 0 rpm to 120 rpm or less. Further, in order to improve uniformity of the film thickness distribution, in some embodiments, the angle of the wafer W at the initiation of the film formation processing coincides with the angle of the wafer W at the termination of the film formation processing. 
         [0080]    The processing shown in the timing chart will be described in order. First, a user sets desired film forming conditions. According to the setting, a processing time is determined by the control unit  6 . If the wafer W is loaded into the vacuum vessel  11 , the rotational speed of the target  41  rises from 0 rpm to V rpm and the angle of the magnet changes from a predetermined angle to an angle of T 1 . Along with the rise of the rotational speed of the target  41  and the change of the magnet angle, the angle of the wafer W is set to be 0 degree (equals to 360 degrees in one revolution). 
         [0081]    When the rotational speed of the target  41  reaches V rpm, the rise of the rotational speed is stopped, and the target  41  continuously rotates at V rpm. Then, if the angle of the magnet is T 1  and the angle of the wafer W is 0 degree, the power is supplied to the target  41  to initiate the film formation processing (at a time t 1  in  FIG. 16 ). During the film formation processing, the target  41  continuously rotates at V rpm, and the magnet arrangement assembly  53  is continuously moved at the constant speed. Further, the wafer W also rotates continuously at a predetermined speed. After the supply of power to the target  41  is initiated, if the wafer W rotates, e.g., eight revolutions, and comes to the angle at the initiation of the film formation and the determined processing time passes, the supply of power to the target  41  is stopped. Thus, the film formation processing is terminated. Along with the stop of the supply of power, the rotation of the wafer W and the movement of the magnet arrangement assembly  53  are stopped (at a time t 2  in  FIG. 16 ). Thereafter, the rotation of the target  41  is also stopped. 
         [0082]    In the film formation processing of the graph of  FIG. 16 , the magnet arrangement assembly  53  is moved in one direction such that the angle becomes from T 1  to T 2 . However, the magnet arrangement assembly  53  may be moved back and forth as described in  FIG. 10 . That is, after the magnet arrangement assembly  53  is moved during the film formation processing such that an angle of the magnet of the magnet arrangement assembly  53  becomes, for example, from T 1  to an arbitrary angle of T 3 , the moving direction may be reversed and the magnet arrangement assembly  53  may be moved such that the angle becomes from T 3  to T 1 . Such movement may be repeatedly performed. 
         [0083]    Subsequently, another configuration example of the magnetron sputtering apparatus will be described.  FIGS. 18 and 19  are a longitudinal sectional side view and a transversal sectional plan view of a magnetron sputtering apparatus  9 , respectively. The magnetron sputtering apparatus  9  has approximately the same configuration as the magnetron sputtering apparatus  1  according to the first modification described in  FIGS. 9 and 10 . There is a difference in that a shutter  91  is installed. The shutter  91  is formed in the shape of, for example, an umbrella, and is installed to divide the target  41  and the stage  21  from each other. A rotating axis  92  is connected to the upper central portion of the shutter  91 . The rotating axis  92  is configured to be rotatable by a rotary mechanism  93  installed at the outside of the vacuum vessel  11 . The rotary mechanism  93  rotates the rotating axis  92  using magnetic force to rotate the shutter  91 . 
         [0084]    The shutter  91  has an opening  94  formed therein. When the film formation processing is performed, in order that the particles scattered from the target  41  are supplied to the wafer W, the opening  94  is positioned below the target  41 . Such a position is represented by a solid line in  FIG. 19 . The state where the opening  94  is in such a position is an open state of the shutter  91 . When the film formation processing is not performed, in order that the target  41  and the wafer W are separated from each other, the opening  94  is positioned to be offset from below the target  41 . This position is represented by a chain line in  FIG. 19 . The state where the opening  94  is in the position is a closed state of the shutter  91 . 
         [0085]      FIG. 20  is a timing chart illustrating an example of the operations of the respective components of the magnetron sputtering apparatus  9 . The timing chart of  FIG. 20  shows the aforementioned graphs  81  to  84  and a graph  85 . The vertical axis of the graph  85  represents an opening/closing state of the shutter  91 . 
         [0086]    The operation of the magnetron sputtering apparatus  9  illustrated in the timing chart of  FIG. 20  will be described with a focus on differences from the operation of the first modification of the magnetron sputtering apparatus  1  already described. In the state where the shutter  91  is closed, the rotational speed of the target  41  is raised to V rpm. Along with that, an angle of the magnet is set to be T 1  and the angle of the wafer W is set to 0 degree. If the rotational speed of the target  41  reaches V rpm, the power is supplied to the target  41  and the target  41  is sputtered. The shutter  91  causes the sputtered particles toward the wafer W to be blocked. If the angle of the magnet is T 1  and the angle of the wafer W is 0 degree, the shutter  91  is opened. Then, the sputtered particles pass through the opening  94  of the shutter  91  and are incident on the wafer W, thereby initiating the sputtering processing (at time t 3 ). If, after the shutter  91  is opened, a processing time determined by the set film forming conditions passes, the supply of power to the target  41  is stopped. Thus, the film formation processing is stopped (at time t 4 ). 
         [0087]    That is, in the above processing, at the timing where the shutter  91  is opened, an initiation timing of the film formation processing is controlled. In the above processing, instead of stopping the supply of power, the shutter  91  may be closed to stop the film formation processing. 
       Evaluation Test 
     Evaluation Test 1 
       [0088]    A leakage magnetic flux density distribution of the target  41  having the magnet arrangement assembly  53  already described was confirmed by a simulation. For the target  41 , a material was Bs (brass), a magnetic flux density was set to 2.2 Teslas, and a thickness was set to 4 mm.  FIGS. 21 and 22  show the simulation result. The figures show a magnetic flux density distribution at a surface spaced apart outward 0.5 mm from the surface of the target  41 . In  FIGS. 21 and 22 , the arrangement direction of the magnets  55  to  57  is referred to as the X direction, the length direction of the cylinder of the target  41  is referred to as the Y direction, and a direction from a leading end side to a proximal end side of the magnets  55  to  57  is referred to as the Z direction. The X, Y, and Z directions are perpendicular to one another.  FIG. 21  shows the magnetic flux density distribution as the target  41  is obliquely viewed.  FIG. 22  shows the magnetic flux density distribution at the XY plane as the target  41  is viewed toward the Z direction. 
         [0089]    A magnetic flux density distribution in an actual measurement result was obtained as a color image by computer graphics with a color and a color density varied according to a magnetic field strength. For convenience in showing  FIGS. 21 and 22 , instead of the color image, each region representing a predetermined range of a magnetic field strength is defined by contour lines. The defined regions are hatched with different patterns, respectively. A region having a magnetic field strength of more than 1200 gausses to 1350 gausses or less is marked in black. A region having a magnetic field strength of more than 1050 gausses to 1200 gausses or less is marked in a mesh pattern. A region having a magnetic field strength of more than 900 gausses to 1050 gausses or less is marked in sloped lines. A region having a magnetic field strength of more than 600 gausses to 900 gausses or less is marked in reverse-sloped lines. A region having a magnetic field strength of more than 300 gausses to 600 gausses or less is marked in relatively dark grayscale. A region having a magnetic field strength of 0 gauss or more to 300 gausses or less is marked in relatively light grayscale. 
         [0090]    In general, in order to perform the magnetron sputtering by applying a DC voltage to the target as a magnetic material, a magnetic field strength leaking from the target is necessarily to become 500 gausses or more. As shown in  FIGS. 21 and 22 , a region having a magnetic field strength of 500 gausses or more was present at the surface of the target  41 . In addition, the highest magnetic field strength of 1200 gausses or more was confirmed. That is, it showed that the magnet arrangement assembly  53  and the target  41  as already described were used to easily perform the film formation processing on the wafer W. 
       Evaluation Test 2 
       [0091]    As Evaluation Test 2-1, a simulation of performing the film formation processing was carried out as shown in the timing chart of  FIG. 16 . That is, in Evaluation Test 2-1, the magnet arrangement assembly  53  was set to be moved during the film formation processing. In addition, a film thickness distribution obtained at each portion of the wafer W by the film formation processing was calculated as a percentage, and 1-sigma (standard deviation) was calculated. Further, as Evaluation Test 2-2, a simulation of performing the film formation processing was carried out without moving the magnet arrangement assembly  53  during the film formation processing. Except that the magnet arrangement assembly  53  was not moved during the film formation processing, the simulation of Evaluation Test 2-2 was carried out under the same film forming conditions as Evaluation Test 2-1. Then, for a film thickness distribution obtained by the simulation, 1-sigma was calculated in the same manner as Evaluation Test 2-1. 
         [0092]    A bar graph of  FIG. 23  shows results of Evaluation Tests 2-1 and 2-2. The vertical axis of the graph represents the 1-sigma. That is, the smaller a numerical value of the vertical axis is, the higher the film thickness uniformity at each portion of the wafer W is. Evaluation Test 2-1 has a 1-sigma of 0.75 or so, and Evaluation Test 2-2 has a 1-sigma of 2.75 or so. That is, Evaluation Test 2-1 has higher film thickness uniformity than Evaluation Test 2-2. Further, for arrangement of the magnets constituting the magnet arrangement assembly  53 , a plurality of patterns were prepared. Evaluation Tests 2-1 and 2-2 were carried out using each pattern. Although the arrangement pattern of the magnets was changed, Evaluation Test 2-1 had higher film thickness uniformity than Evaluation Test 2-2. That is, it showed that the film thickness uniformity could be improved by moving the magnet arrangement assembly  53  during the film formation processing.