Cathode unit for magnetron sputtering device and magnetron sputtering device

Abstract

A cathode unit for a sputtering device (SM) and a sputtering device are provided, which have a function of periodically removing a re-deposited film formed in a non-etched region remaining on a central region of a target, and which can form a film with good coverage on the entire surface of a substrate having a recess with a high aspect ratio. The cathode unit (CU1) includes a plurality of first and second magnet units (61, 62) disposed on a side opposite to a sputtering surface (51) of a target (5) and each rotatably driven around an axis (Cl). The first magnet unit is configured to cause a first leakage magnetic field (Mf1) to act on a space in front of the sputtering surface including a target center (Tc) on an inner side. The second magnet unit is configured to cause a second leakage magnetic field (Mf2) to locally act on the space in front of the sputtering surface between the target center and a target outer edge portion, and to enable self-sustained discharge of plasma enclosed by the second leakage magnetic field at a low pressure.

Description

TECHNICAL FIELD

[0001] The present application relates to a cathode unit for a magnetron sputtering device and a magnetron sputtering device provided with the cathode unit. BACKGROUND

[0002] In a semiconductor device manufacturing process, for example, there is a film forming process of forming a copper film on a substrate surface including an inner surface (inner side wall and bottom surface) of a recess such as a via hole or a trench formed on a silicon wafer as a processed substrate (hereinafter referred to as "substrate"). In such a film forming process, a magnetron sputtering device is generally used. Such a magnetron sputtering device has a vacuum chamber in which a substrate is arranged, and a cathode unit is provided in the vacuum chamber. The cathode unit is provided with a target which is arranged in a posture facing the vacuum chamber opposite to the substrate, and a magnet unit which is arranged on a side of the target opposite to a sputtering surface.

[0003] As the magnet unit, a magnet (so-called balanced magnet) having a first magnet in which a single or a plurality of magnet pieces having a cylindrical profile are arranged in a ring or a heart shape, and a second magnet in which a plurality of magnet pieces are arranged at equal intervals around the first magnet, is generally used. The volume of the first magnet and the second magnet is designed to be the same (1:1) when converted to the same magnetization. With this magnet unit, a leakage magnetic field in which a position where a vertical component of a magnetic field is zero is annularly closed locally acts on a front space of the sputtering surface between the center of the target and the outer edge of the target (for example, refer to Patent Literature 1). Then, in the vacuum chamber in a vacuum atmosphere, a rare gas (sputtering gas) such as argon is introduced at a prescribed flow rate, and when direct current power with a negative potential is applied to the target, for example, a ring-shaped plasma is generated from the center of the target to the front space of the sputtering surface. Thus, ions of the sputtering gas ionized by the plasma sputter the sputtering surface of the target. In the sputtering, by rotating and driving the magnet unit at a prescribed number of revolutions around an axis passing through the center of the target, a copper film can be formed on the entire surface of the substrate including the inner surface of the recess with good coverage.

[0004] When sputtering the target as described above, a non-erosion region in which the target is substantially not eroded by sputtering remains on the central region of the target. In the non-erosion region, as sputtering proceeds, a so-called re-deposition film is formed by the sputtering particles adhering again, and the re-deposition film becomes a source of particle generation, for example, and becomes a major cause of reducing the yield of products. Therefore, there is a problem that the re-deposition film must be effectively removed before it is formed to a prescribed thickness or more. On the other hand, in recent years, as wiring patterns are further miniaturized, the recess as a film forming object also has a higher aspect ratio. Therefore, it is also required to be able to form a film on the entire surface of the substrate including the inner surface of the recess with a high aspect ratio with good coverage, that is, to be able to satisfy the requirement of improving the coverage.

[0005] PRIOR ART DOCUMENTS

[0006] Patent Literature

[0007]

Patent Literature 1

[0008] Means for solving the technical problem

[0009] In view of the above, the technical problem to be solved by the present application is to provide a cathode unit for a magnetron sputtering device and a magnetron sputtering device, which have a function of being able to periodically remove a re-deposited film formed in a non-etched region remaining on a central region of a target, and which are able to form a film with good coverage on the entire surface of a substrate having a recess with a high aspect ratio.

[0010] Means for solving the technical problem

[0011] In order to solve the above technical problem, the cathode unit for a magnetron sputtering device of the present application has a plurality of first and second magnet units, which are disposed on a side opposite to a sputtering surface of a target set in a posture facing the inside of a vacuum chamber, and are respectively rotationally driven around an axis extending in a direction orthogonal to the sputtering surface, characterized in that the first magnet unit is configured so that a first leakage magnetic field, in which a position where a perpendicular component of a magnetic field is zero is annularly closed, acts on a space in front of the sputtering surface containing a center of the target on an inner side, and the second magnet unit is configured so that a second leakage magnetic field, in which a position where a perpendicular component of a magnetic field is zero is annularly closed, locally acts on the space in front of the sputtering surface between the center of the target and an outer edge portion of the target, and self-sustained discharge of plasma enclosed by the second leakage magnetic field at a low pressure is possible.

[0012] In the present application, the first magnet unit can adopt a structure in which self-discharge of plasma enclosed by the first leakage magnetic field at a low pressure is not possible. On the other hand, a structure can be adopted which has a drive unit that moves the first magnet unit and the second magnet unit in directions approaching and away from the sputtering surface of the target, respectively.

[0013] Further, in order to solve the above technical problem, the magnetron sputtering device of the present application is characterized by including: the cathode unit for a magnetron sputtering device; a vacuum chamber in which the cathode unit is disposed in a posture in which a target surface of the cathode unit faces the inside of the vacuum chamber, and a processed substrate is disposed; a sputtering power source that applies electric power to the target; a gas introduction device that can introduce a sputtering gas into the vacuum chamber in a vacuum atmosphere; and a shield plate that is disposed in a manner of surrounding a front of the target in the vacuum chamber, and is applied with a prescribed potential. In this case, a structure can be adopted in which a stage is disposed in the vacuum chamber, and the processed substrate is disposed thereon, and a bias power source that applies a bias voltage to the stage is provided.

[0014] In the above manner, after the cathode unit is set in the attitude of the target surface facing the vacuum chamber, the vacuum in the vacuum chamber is exhausted to a prescribed pressure. In the vacuum chamber in a vacuum atmosphere, a rare gas (sputtering gas) such as argon is introduced at a prescribed flow rate, for example, a direct current power with a negative potential is applied to the target. Thus, a first annular plasma is generated in the space in front of the sputtering surface including the center of the target on the inside, and a second annular plasma deviated from the center of the target is generated in the space in front of the sputtering surface between the center of the target and the outer edge portion of the target. At this time, for example, if the first magnet unit is set to a structure in which self-discharge of the plasma at a low pressure cannot be performed, then, after the introduction of the sputtering gas is stopped in a state in which the vacuum chamber is exhausted, the first plasma disappears, and the second plasma self-discharges at a low pressure. Then, using argon ions in the second plasma, mainly the portion of the sputtering surface substantially coinciding with the projection plane of the second plasma is sputtered, and in the sputtering, the second magnet unit is driven to rotate around the axis passing through the center of the target at a prescribed number of revolutions (i.e., rotates on the same circumference with the center of the target as the center), and thus, a film is formed on the substrate disposed in the attitude toward the target side on the entire surface including the inner surface of the recess portion (film formation step). In addition, the substrate can be covered with a shutter or the like during a period until the second plasma self-discharges stably at a low pressure. Next, when a re-deposited film of a prescribed thickness or more is formed due to the non-etched region remaining on the central region of the target, as with the above, the sputtering gas is introduced at a prescribed flow rate, and a direct current power is applied to generate each of the first and second plasmas, and a prescribed time is maintained. Thus, using argon ions in the first plasma, the re-deposited film formed on the sputtering surface is also removed by sputtering (removal step).

[0015] It is advantageous to use a self-discharge technique capable of achieving high density of plasma to form, for example, a copper film on the entire substrate on the inner surface of a recess portion with a high aspect ratio, and as the magnet unit at this time, in order to generate a magnetic leakage field with high electron confinement capability, unlike the prior example, attention is paid to a so-called unbalanced magnet in which the volume when converted into the same magnetization is different between the first magnet and the second magnet, and by adopting the above structure, it has a function of being able to periodically remove the re-deposited film formed in the non-etched region remaining on the central region of the target, and can form a film on the entire surface of the substrate of the recess portion with a high aspect ratio with good coverage. Moreover, since the first plasma for removing the re-deposited film and the second plasma for forming a film on the substrate are generated separately by each of the first and second magnet units, the second plasma used in the film formation step always sputters the portion of the sputtering surface on the same circumference, and thus, after the removal step, there is no such adverse situation that the distribution of scattering of sputtering particles greatly changes.

[0016] However, it is preferable that the first magnet unit and the second magnet unit are arranged apart from each other in a manner that magnetic field interference is not generated (for example, arranged at a phase of 180° around the rotation axis), and that the film forming process and the removal process are respectively rotated and driven by the first magnet unit and the second magnet unit in synchronization with each other around the rotation axis. However, depending on the size of the substrate to be formed with a film and the aspect ratio of the recess, and the like, it is sometimes necessary to arrange the first magnet unit and the second magnet unit close to each other to such an extent that magnetic field interference is likely to be generated. In this case, a structure can be adopted in which a driving unit is provided which moves the first magnet unit and the second magnet unit in directions approaching and separating from the sputtering surface of the target, respectively.

[0017] Thus, in the film forming process, the first magnet unit is moved to a position away from the sputtering surface of the target by the driving unit, and the second magnet unit is moved to a position close to the sputtering surface of the target in a manner that magnetic field interference is not generated. On the other hand, in the removal process, the second magnet unit is moved to a position away from the sputtering surface of the target by the driving unit, and the first magnet unit is moved to a position close to the sputtering surface of the target in a manner that magnetic field interference is not generated. Thus, the function of periodically removing the re-deposited film formed in the non-etching region on the central region of the target without being affected by magnetic field interference is achieved, and a film can be formed with good coverage on the entire surface of the substrate having a recess with a high aspect ratio. At this time, the first magnet unit can be either of a balanced magnet and an unbalanced magnet, as long as the re-deposited film can be removed by sputtering.

[0018] Further, if a shield plate to which a prescribed potential (for example, +5 to 200 V) is applied is arranged in a manner surrounding the front of the target inside the vacuum chamber in the above-described magnetron sputtering device, then in the removal process, the first plasma can be prevented from becoming unstable, and in the film forming process, ionization of the sputtering particles flying from the target can be promoted. Further, if a bias power is applied to the stand in the sputtering process, then by actively introducing the ionized sputtering particles to the substrate, a film can be formed with good coverage on the entire surface of the substrate having a recess with a high aspect ratio more reliably. Further, in order to form a film with good coverage on the entire surface of the substrate having a recess with a high aspect ratio, a collimator can also be provided between the target and the substrate inside the vacuum chamber. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 (a) of FIG. 1 is a cross-sectional view illustrating the structure of a magnetron sputtering device according to a first embodiment, and (b) is a plan view of a cathode unit according to the first embodiment.

[0020] Figure 2 (a) and (b) of FIG. 2 are cross-sectional views illustrating the structure of a cathode unit according to a second embodiment. DETAILED DESCRIPTION

[0021] The following describes an embodiment of the cathode unit CU1 of the magnetron sputtering device and the magnetron sputtering device SM provided with the cathode unit CU1, with reference to the drawings, in a case where a silicon wafer on which a recess such as a through-hole or a groove is formed is set as a substrate (hereinafter referred to as "substrate Sw") to be processed as a processing target, and a copper film is formed on the surface of the substrate Sw. Hereinafter, the terms such as "upper" and "lower" are shown in the setting posture of the magnetron sputtering device SM. Figure 1 The following describes an embodiment of the cathode unit CU1 of the magnetron sputtering device and the magnetron sputtering device SM provided with the cathode unit CU1, with reference to the drawings, in a case where a silicon wafer on which a recess such as a through-hole or a groove is formed is set as a substrate (hereinafter referred to as "substrate Sw") to be processed as a processing target, and a copper film is formed on the surface of the substrate Sw. Hereinafter, the terms such as "upper" and "lower" are shown in the setting posture of the magnetron sputtering device SM.

[0022] With reference to Figure 1 (a) and (b), the magnetron sputtering device SM of the present embodiment provided with the cathode unit CU1 of the first embodiment is provided with a vacuum chamber 1. An exhaust port 11 is formed in the vacuum chamber 1, and one end of an exhaust pipe 21 is connected thereto. The other end of the exhaust pipe 21 is connected to a vacuum pump 2 composed of a rotary pump, a cryogenic pump, or a turbo molecular pump, and the like, and can vacuum-exhaust the inside of the vacuum chamber 1 to a predetermined pressure. A gas introduction port 12 is also formed in the vacuum chamber 1, and one end of a gas introduction pipe 31 is connected thereto. The other end of the gas introduction pipe 31 is in communication with a gas source outside the drawing through a flow rate adjusting valve 32 composed of a mass flow controller, or the like, and can introduce argon gas (noble gas) as a sputtering gas at a controlled flow rate into the vacuum chamber 1. In the present embodiment, the gas introduction mechanism is composed of the gas introduction pipe 31 and the flow rate adjusting valve 32.

[0023] In the lower portion of the vacuum chamber 1, a stage 4 is disposed at intervals by an insulator 4a, and the substrate Sw is set in a posture with its film formation surface (surface on which the recess is formed) facing upward. The stage 4 is composed of a base 41 of a metal material having a cylindrical profile and a chuck plate 42 adhered to the upper surface of the base 41, and can hold the substrate Sw by electrostatic chucking during sputter film formation. As the electrostatic chuck, a known product such as a unipolar or bipolar type can be used. In this case, a passage for coolant circulation or a heater can also be assembled on the base 41, and the substrate Sw can be controlled to a predetermined temperature during film formation. An output from a bias power supply 43 is also connected to the stage 4, and bias power can be applied to the stage 4 during sputter film formation. In addition, although not particularly shown, a shield to prevent sputtering particles from adhering to the substrate Sw can be provided during a period until the second plasma mentioned later is stabilized by self-sustained discharge at a low pressure. Furthermore, in the upper portion of the vacuum chamber 1, the cathode unit CU1 of the first embodiment is detachably installed, and is opposed to the substrate Sw on the stage 4 with the target center Tc and the center Sc of the substrate Sw located on the same axis Cl. The distance between the target 5 and the substrate Sw (T-S distance) is set in a range of 200 to 1000 mm in consideration of the straightness of sputtering particles.

[0024] The cathode unit CU1 has: a target 5 of copper material, which is disposed in a posture facing the inside of the vacuum chamber 1; first and second magnet units 61, 62, which are located outside the vacuum chamber 1, disposed on the upper side of the sputtering surface 51 of the target 5, and configured to face each other; and a drive unit 7, which rotates and drives the first and second magnet units 61, 62 around rotation axes Cl orthogonal to the sputtering surface 51 of the target 5. The target 5 is a target having a circular plan view, which is produced according to the profile of the substrate Sw by a known method, and a back plate 52, which cools the target 5 during sputtering film formation, is joined to the upper surface of the target 5. Then, in a state where the target 5 is joined to the back plate 52, a spacer insulator 13 is installed in the upper portion of the vacuum chamber 1. As the target 5, a target of a metal material such as aluminum, tantalum, or titanium can be used in addition to copper. Further, an output from a known sputtering power source Ps is connected to the target 5, and, when sputtering film formation is performed, direct current power (for example, 5 kW to 50 kW) having a negative potential or pulse-shaped direct current power can be applied, for example.

[0025] Also with reference to Figure 1 (b), the first magnet unit 61 has a disc-shaped yoke 61a, and a plurality of permanent magnet pieces are arranged in a circular or heart-shaped profile on the lower surface of the yoke 61a in a manner that changes the polarity of the target 5 side (the lower surface side thereof) of each other. In this case, the first magnet 61b and the second magnet 61c use magnets designed to have the same volume (1:1) when converted to homomagnetization (so-called balanced magnets). Further, a first leakage magnetic field Mfl, which has a position where the vertical component of the magnetic field is zero and is annularly closed, acts on the front space of the sputtering surface 51 containing the target center Tc on the inside, and, as mentioned later, self-discharge of plasma enclosed by the first leakage magnetic field Mfl at low pressure cannot be performed. On the other hand, the second magnet unit 62 has a disc-shaped yoke 62a, and a plurality of permanent magnet pieces are arranged in a circular or heart-shaped profile on the lower surface of the yoke 62a in a manner that changes the polarity of the target 5 side (the lower surface side thereof) of each other. In this case, the third magnet 62b and the fourth magnet 62c use magnets designed to have a smaller volume (for example, 1:4) when converted to homomagnetization compared to the fourth magnet 62c (so-called unbalanced magnets), and a second leakage magnetic field Mf2, which has a position where the vertical component of the magnetic field is zero and is annularly closed, partially acts on the front space of the sputtering surface 51 between the target center Tc and the outer edge portion of the target 5, and self-discharge of plasma enclosed by the second leakage magnetic field Mf2 at low pressure can be performed.

[0026] The drive unit 7 has a solid first rotary shaft 71 and a hollow second rotary shaft 72 arranged concentrically with each other. A first magnet unit 61 is provided at the lower end of the first rotary shaft 71, and a second magnet unit 62 is provided at the lower end of the second rotary shaft 72 by a support arm 71a extending in a direction orthogonal to the rotary axis Cl (a direction extending parallel to the sputtering surface 51). In this case, the first rotary shaft 71 is connected at the lower end at a position offset in the radial direction from the center of the magnetic yoke 61a, and the support arm 71a is arranged to extend in the opposite direction to the direction in which it is offset in the radial direction (i.e., offset by 180° in phase around the rotary axis Cl so that magnetic field interference between the first magnet unit 61 and the second magnet unit 62 is minimized), and the lower surfaces of the first magnet 61b and the second magnet 61c and the third magnet 62b and the fourth magnet 62c are arranged on the same plane parallel to the sputtering surface 51. Although not specifically illustrated, a known mechanism can be provided on the support arm 71a to allow it to be extended and retracted in the radial direction, so that the distance from the rotary axis Cl of the first magnet unit 61 can be varied. Further, the drive unit 7 has a motor Ml connected to the first rotary shaft 71 and a motor M2 connected to the second rotary shaft 72, and is capable of rotating and driving the first rotary shaft 71 and the second rotary shaft 72 at a predetermined speed. At this time, the rotational speeds of the first magnet unit 61 and the second magnet unit 62 are set in such a way that the phase around the rotary axis Cl is always constant, so that magnetic field interference is minimized.

[0027] In the vacuum chamber 1, a shield plate 8 is arranged in front of the target 5 in such a way as to surround it, and a predetermined potential is applied to the shield plate 8 by a direct current power source 8a during sputter film formation. Thus, the copper atoms ionized in the plasma can be bounced back by the shield plate 8, so that the first plasma can be prevented from becoming unstable, and ionization of the sputtered particles (copper atoms) flying from the sputtering surface 51 of the target 5 toward the substrate Sw can be promoted during the film formation process. A coil 9 is also provided outside the vacuum chamber 1, and a vertical magnetic field (not shown) is generated from the target 5 toward the substrate Sw by energizing the coil 9 with a coil power source 9a, so that ionization of the atoms flying from the target 5 is further promoted. Further, a collimator Cm is arranged in the vacuum chamber 1 between the target 5 and the substrate Sw. As the collimator Cm, a known product can be used, and therefore a detailed description is omitted here. The following describes film formation of a copper film using the sputter device SM having the cathode unit CUl of the first embodiment.

[0028] After the substrate Sw is arranged on the stage 4, the vacuum chamber 1 is evacuated to a predetermined pressure (for example, 10 -5 Pa) by the vacuum pump 2. Argon is introduced into the vacuum chamber 1 in a vacuum atmosphere at a predetermined flow rate so that the total pressure is 10 -2A direct current power (5 to 50 kW) with a negative potential is applied to the target 5 in the range of -1 Pa. Thus, a first annular plasma is generated in the space in front of the sputtering surface 51 including the target center Tc, and a second annular plasma deviated from the target center Tc is generated in the space in front of the sputtering surface 51 between the target center Tc and the outer peripheral portion of the target 5. After that, when the introduction of argon gas is stopped in a state where the vacuum chamber 1 is vacuum-exhausted, the first plasma disappears, and the second plasma performs self-sustained discharge at a low pressure. Then, using argon ions in the second plasma, a portion of the sputtering surface 51 substantially coinciding with the projection plane of the second plasma is mainly sputtered, and in the sputtering, the first and second magnet units 61, 62 are driven to rotate around the rotation axis Cl at a prescribed number of revolutions. Thus, a copper film is formed on the entire surface of the substrate Sw including the inner surface of the recess portion (film forming step) with good coverage. Next, when a re-deposited film (not shown) of a prescribed thickness or more is formed due to the non-erosion region remaining on the central region of the target 5, as with the above, a sputtering gas is introduced at a prescribed flow rate, a direct current power is applied to generate the first and second plasmas, and only a prescribed time is maintained. Thus, using argon ions in the first plasma, the re-deposited film formed on the sputtering surface 51 is also removed by sputtering (removal step).

[0029] In the above-described manner, by using the self-sustained discharge technique capable of achieving high-density plasma, a copper film can be formed on the entire surface of the substrate Sw including the inner surface of the recess portion with good coverage, and further, a re-deposited film formed in the non-erosion region remaining on the central region of the target 5 can be periodically removed. Moreover, the first plasma for removing the re-deposited film and the second plasma used in the film forming of the substrate Sw are generated separately, and since the second plasma used in the film forming step always sputters a portion of the sputtering surface 51 located on the same circumference, no adverse situation such as a large change in the scattering distribution of sputtering particles after the removal step occurs. Moreover, since the shield plate 8 to which a prescribed potential is applied is provided, the first plasma can be prevented from becoming unstable at the time of the removal step, and ionization of sputtering particles (copper atoms) scattered from the target 5 can be promoted at the time of the film forming step. Further, since a bias power is applied to the stand 4 during sputtering, ionized sputtering particles are actively introduced to the substrate Sw, and thus film formation with good coverage on the entire surface of the substrate Sw having a high aspect ratio (for example, 2 to 10) of the recess portion can be more reliably performed.

[0030] Here, unlike the first embodiment described above, to achieve good film coverage on the recess and reliably remove the redeposited film, it is sometimes necessary to arrange the first magnet unit 61 and the second magnet unit 62 close together, even to the point where magnetic field interference may occur. Therefore, in the cathode unit CU2 of the second embodiment, a driving unit 70 is provided, which positions the first magnet unit 61 and the second magnet unit 62 in a direction close to the sputtering surface 51 away from the target 5 ( Figure 2 Move upwards (in the vertical direction). The following refers to the drawing where the same reference numerals are used to label the same parts or elements. Figure 2 The structure of the cathode unit CU2 in the second embodiment will be described in detail.

[0031] like Figure 2 As shown in (a) and (b), the cathode unit CU2 of the second embodiment includes a support frame 701 provided on a back plate 52. A mounting opening 703 is formed on a first support plate portion 702 of the support frame 701, which is arranged parallel to the sputtering surface 51. A first rotating shaft 71 and a second rotating shaft 72 pass through the mounting opening. A first drive plate 712 is connected to a portion of the first rotating shaft 71 protruding upward from the second rotating shaft 72. This drive plate 712 has a bearing 711 supporting the first rotating shaft 71, and moves up and down via a drive mechanism 713 such as a cylinder or a direct start motor provided on the first support plate portion 702. Furthermore, the upper end portion 714 of the first rotating shaft 71 is formed as a spline shaft portion, which engages with a sleeve-shaped first ball spline nut 704. This nut is mounted on the second support plate portion 703 of the support frame 701, which is arranged parallel to the first support plate portion 702. A first gear 705 is formed on the outer peripheral surface of the first ball spline nut 704, and a second gear 706 disposed on the output shaft of the motor M3 meshes with the first gear 705. Thus, by rotating the drive motor M3, the first rotating shaft 71 is driven to rotate at a predetermined speed. In this case, the first rotating shaft 71 can also be supported by a bearing 707 disposed on the inner surface of the second rotating shaft 72.

[0032] Furthermore, a second drive plate 722 is connected to the second rotating shaft 72, which includes a bearing 721 supporting the rotating shaft. The second drive plate 722 moves up and down via a drive mechanism 723, such as a cylinder or a direct-drive motor, mounted on the first support plate portion 702. Additionally, the upper end of the second rotating shaft 72, located above the mounting opening 703, is formed as a spline shaft portion (not shown), which engages with a sleeve-shaped second ball spline nut 724, the lower end of which is inserted into the mounting opening 703. A first gear 725 is formed on the outer circumferential surface of the second ball spline nut 724, and a second gear 726 mounted on the output shaft of the motor M4 meshes with the first gear 725. Thus, by rotating the drive motor M4, the first rotating shaft 71 is rotated at a predetermined speed.

[0033] Based on the above, after the substrate Sw is placed on the stage 4, the vacuum in the vacuum chamber 1 is evacuated to the specified pressure using the vacuum pump 2. At this point, the first magnet unit 61 rises to a position away from the backplate 52 via the drive unit 70, and the second magnet unit 62 descends to a position close to the backplate 52, in front of the sputtering surface 51. Figure 2 The space below the vacuum chamber (where only the second leakage magnetic field Mf2 acts) then. Argon gas is then introduced into the vacuum chamber 1 in a vacuum atmosphere at a specified flow rate to maintain a total pressure of 10. -2 Within a range of ~1 Pa, a negatively charged DC power (5-50 kW) is applied to the target 5. As a result, only a ring-shaped second plasma, deviating from the target center Tc, is generated in the space in front of the sputtering surface 51 located between the target center Tc and the outer edge of the target 5. Then, when the introduction of sputtering gas is stopped while the vacuum chamber 1 is evacuated, the second plasma self-sustains discharge at low pressure. Thus, using argon ions in the second plasma, the portion of the sputtering surface 51 that is approximately aligned with the projection plane of the second plasma is primarily sputtered. During sputtering, the second magnet unit 62 is driven to rotate around the rotation axis C1 at a predetermined number of revolutions. At this time, the first magnet unit 61 is driven to rotate around the rotation axis C1 at a predetermined number of revolutions. Furthermore, similarly, a predetermined potential (e.g., +5-200 V) is applied to the shielding plate 8, and the coil 9 is energized (e.g., 0.5-15 A), generating a magnetic field perpendicular to the sputtering surface 51. Furthermore, a bias power in the range of 10-1000 W is applied to the stage 4. Thus, a film is formed on the entire surface of the substrate Sw, including the inner surface of the recess (film formation process).

[0034] Next, the following state is formed: when a redeposited film of a specified thickness or more is formed due to the non-erosion area remaining on the central region of the target 5, the second magnet unit 62 is raised to a position away from the back plate 52 by the drive unit 70, and the first magnet unit 61 is lowered to a position close to the back plate 52, and the first leakage magnetic field Mf1 acts in front of the sputtering surface 51. Figure 1 (The space below). Then, with a dummy substrate (not shown) set on the stage 4, argon gas is introduced at a specified flow rate to bring the total pressure to 10, as described above. -2 A negatively charged DC power (5-50 kW) is applied to the target 5 within a range of ~1 Pa. To achieve discharge stability, a predetermined potential (e.g., +5-200 V) is preferably applied to the shielding plate 8. The redeposited film is then removed by sputtering with argon ions in the first plasma (removal process). In this case, the first magnet unit 61 can be either a balanced magnet or an unbalanced magnet, as long as it can remove the redeposited film by sputtering.

[0035] The above describes the embodiments of the present application, but various modifications can be made without departing from the technical idea of the present application. In the above-described embodiments, the case where the processed substrate is a silicon wafer having a recess such as a via hole or a trench formed on the surface thereof is described as an example, but the present application is not limited thereto and can be widely applied to a case where a prescribed metal film is formed on the surface of a processed substrate with good in-plane uniformity in film thickness. In the above-described embodiments, the case where two magnet units 61 and 62 are provided is described as an example, but the present application can be applied to a case where three or more magnet units are provided. In the above-described embodiments, the case where permanent magnet pieces are used as the first and second magnet units 61 and 62 is described as an example, but the present application is not limited thereto. For example, a part of the permanent magnet pieces can be provided as an electromagnet, and the first and second magnet units 61 and 62 can be appropriately switched between a balanced magnet and an unbalanced magnet by appropriately controlling the energization of the electromagnet.

[0036] BRIEF DESCRIPTION OF DRAWINGS

[0037] CU1, CU2. Cathode unit for magnetron sputtering device, SM. Magnetron sputtering device, Sw. Substrate (processed substrate), 1. Vacuum chamber, 31. Gas introduction pipe (constituent element of gas introduction mechanism), 32. Flow rate adjusting valve (constituent element of gas introduction mechanism), 4. Stage, 43. Bias power supply, 5. Target, 51. Sputtering surface, Ps. Sputtering power supply, 61. First magnet unit, 62. Second magnet unit, Cl. Axis, Mf1. First leakage magnetic field, Mf2. Second leakage magnetic field, 7, 70. Driving unit, 8. Shield plate.

Claims

1. A cathode unit for a magnetron sputtering apparatus, characterized in that: It has a first magnet unit and a second magnet unit, which are arranged on the side opposite to the sputtering surface of the target, which is set in an attitude facing the vacuum chamber, and are respectively driven to rotate about an axis extending in a direction orthogonal to the sputtering surface. The first magnet unit is configured such that a first leakage magnetic field, which is closed in a ring at a position where the vertical component of the magnetic field is zero, acts on the space in front of the sputtering surface containing the target center on the inner side. The second magnet unit is configured such that the vertical component of the magnetic field is zero, and the second leakage magnetic field is closed in a ring shape, which locally acts on the space in front of the sputtering surface located between the target center and the outer edge of the target. It includes a drive unit that moves the first magnet unit and the second magnet unit in directions that are close to or away from the sputtering surface of the target, respectively. The drive unit is configured such that when either the first magnet unit or the second magnet unit is moved to a position close to the sputtering surface of the target, the other magnet unit is moved to a position away from the sputtering surface of the target where no magnetic field interference will occur. The first magnet unit is configured to be unable to perform self-sustaining discharge of plasma under low pressure by being confined by the first leakage magnetic field, and the second magnet unit is configured to enable self-sustaining discharge of plasma under low pressure by being confined by the second leakage magnetic field.

2. A magnetron sputtering apparatus, characterized in that, include: Cathode unit for magnetron sputtering apparatus as described in claim 1; A vacuum chamber, which is equipped with a substrate to be processed, and the target of the cathode unit is positioned facing the interior of the vacuum chamber; a sputtering power supply that applies power to the target; a gas introduction device that can introduce sputtering gas into the vacuum chamber in a vacuum atmosphere; and a shielding plate that is positioned in the vacuum chamber around the front of the target and is subjected to a predetermined potential.

3. The magnetron sputtering apparatus according to claim 2, characterized in that: A platform is provided in the vacuum chamber, and the substrate to be processed is placed on it; It has a bias power supply that applies bias power to the test bench.

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