Apparatus and method for depositing film with method of magnetron sputtering

Abstract

To form a homogeneous insulation coating by stably performing film deposition process to form an insulation coating in an apparatus and a method for depositing a film with a method of magnetron sputtering.SOLUTION: A magnetron sputtering apparatus 10 according to the present invention uses an earth shield 26 as a positive electrode and a magnetron sputtering cathode 24 as a negative electrode and induces glow discharge when those electrodes are supplied with sputtering electric power Es; uses the earth shield 26 as a positive electrode and a cathode filament 30 as a negative electrode and induces arc discharge when the cathode filament 30 is supplied with cathode electric power Ec and those electrodes are supplied with arc discharging electric power Ed; and includes a red-heat anode filament 70 that is installed in the vicinity of the earth shield 26 to stabilize a plasma 300 caused by the glow discharge and arc discharge, thereby stably performing film deposition process for forming an insulation coating.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a film formation apparatus and a film formation method using magnetron sputtering, and more particularly to a film formation apparatus and a film formation method using magnetron sputtering for forming an insulating film on a workpiece. [Background technology]

[0002] Patent Document 1 discloses an example of a film formation technique using magnetron sputtering, particularly a so-called reactive magnetron sputtering technique for forming a reactive film (compound film) on a workpiece. According to the so-called conventional technique disclosed in Patent Document 1, a magnetron sputtering cathode (magnetron cathode) having a target serving as a reactive film material is provided in a vacuum chamber at ground potential. The workpiece is then placed in the vacuum chamber, specifically, facing the target's roughly rectangular, planar sputtering surface. Furthermore, an earth shield is provided surrounding the magnetron sputtering cathode, with only the target's sputtering surface exposed. This earth shield is also at ground potential. The vacuum chamber is evacuated by a vacuum pump, and an inert gas is introduced into the vacuum chamber as a discharge gas. In this state, the vacuum chamber serves as the anode (strictly speaking, the earth shield serves as the anode) and the magnetron sputtering cathode serves as the cathode, and sputtering power is supplied to both. This causes the inert gas particles to discharge, generating magnetron plasma that sticks to the sputtering surface of the target. The magnetron plasma discharge mode is a high-voltage, low-current glow discharge. The magnetron plasma sticks to the sputtering surface of the target due to the action of a magnetic field formed in the vicinity of the sputtering surface by a magnet that serves as a magnetic field generating means provided in the magnetron sputtering cathode.

[0003] Particles of the inert gas in the magnetron plasma, particularly ions, collide with the sputtering surface of the target, knocking out particles constituting the target from the sputtering surface, i.e., sputtering. The sputtering area, which is the area to be sputtered, is limited to the sputtering surface of the target, i.e., the aforementioned earth shield is provided to ensure this. Furthermore, a reactive gas, which is the material for the reactive film, is introduced into the vacuum chamber. The reactive gas particles are decomposed by the magnetron plasma. Then, bias power is supplied to the vacuum chamber, which serves as the anode, and the workpiece, which serves as the cathode. This accelerates the inert gas particles, reactive gas particles, and sputtered particles from the sputtering surface of the target toward the workpiece. In particular, the reactive gas particles and sputter particles adhere to the workpiece surface and react with each other, forming a reactive film on the workpiece surface, composed of reactive gas particles and sputter particles. Additionally, the bombardment effect of the inert gas particles on the workpiece surface increases the density of the reactive film.

[0004] Additionally, a linear cathode filament (filament) is provided between the sputtering surface of the target and the workpiece in the vacuum chamber, extending along the longitudinal direction of the sputtering surface. Heating power (thermionic emission power) is supplied to the cathode filament, causing it to heat and emit thermoelectrons. Furthermore, arc discharge power (discharge power) is supplied to both the vacuum chamber (strictly speaking, the earth shield as the anode and the cathode filament as the cathode). The thermoelectrons emitted from the cathode filament are accelerated toward the earth shield, where they collide with inert gas particles, reactive gas particles, and sputter particles. Because the aforementioned magnetic field is formed around the cathode filament, the electrons accelerated from the cathode filament toward the earth shield undergo a spiral motion (cycloidal or trochoidal motion) due to the effect of the magnetic field. This increases the frequency with which the thermal electrons collide with inert gas particles, reactive gas particles, and sputter particles, inducing a low-voltage, high-current arc discharge around the cathode filament. In other words, in addition to the magnetron plasma generated by the glow discharge (magnetron sputter discharge), an extremely high-density plasma generated by the arc discharge is generated around the cathode filament, i.e., between the sputtering surface of the target and the workpiece.

[0005] Therefore, sputtered particles sputtered from the sputtering surface of the target pass through a space of extremely high-density plasma on their way toward the workpiece. This activates the sputtered particles, giving them energy at least higher than their ground state, and they are ionized particularly efficiently. Similarly, reactive gas particles are also activated and ionized efficiently. At the same time, inert gas particles are also activated and ionized efficiently. This improvement in ionization rate increases the number of ions incident on the surface of the workpiece, thereby enhancing the hardness of the reaction film formed on the surface of the workpiece. Furthermore, the mutual bonding force between the sputtered particles and the reactive gas particles is increased, resulting in a densified reaction film. Additionally, the bombardment effect of the inert gas particles on the surface of the workpiece is enhanced, further improving the density of the reaction film. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-66483 Summary of the Invention [Problem to be solved by the invention]

[0007] According to the above-mentioned prior art, it is possible to form an insulating film as a reaction film, but in that case, there is a problem that the film formation process cannot be carried out stably, and therefore it is not possible to form a homogeneous insulating film. The reasons for this are as follows.

[0008] The earth shield functions as an anode for both glow discharge and arc discharge. However, when an insulating coating is formed on the surface of the earth shield, the insulating coating (strictly speaking, the insulating material that constitutes the insulating coating) adheres to the surface of the earth shield. If this phenomenon continues, the surface of the earth shield becomes covered with the insulating coating, preventing the earth shield from functioning as an anode. The inner wall of the vacuum chamber then functions as the anode instead of the earth shield. However, the insulating coating naturally adheres to the inner wall of the vacuum chamber, reducing its function as an anode. On the other hand, the insulating coating is difficult to adhere to in some areas of the inner wall of the vacuum chamber, particularly in recessed areas such as the periphery of the exhaust port, the periphery of the observation window, and the mounting flanges of various components. The presence of these areas barely allows discharge to be maintained. However, when observing the inside of the vacuum chamber in this state, the discharge is unstable, and the generation of plasmoids, or masses of plasma, is observed in various locations in the area that functions as an anode to maintain the discharge. These plasmoids repeatedly appear and disappear. Furthermore, in the areas where plasmoids are observed, a significant temperature rise (over 130°C despite water cooling) is observed, and in extreme cases, the area becomes red-hot, melting stainless steel components. This phenomenon can cause the aforementioned problem of instability in the film formation process for forming the insulating coating, resulting in the inability to form a uniform insulating coating. This problem is particularly severe for workpieces with large surface areas (areas to be formed).

[0009] Therefore, an object of the present invention is to provide a novel technology that enables stable film formation processing for forming an insulating coating in a film formation apparatus and film formation method using magnetron sputtering, and ultimately enables the formation of a homogeneous insulating coating. [Means for solving the problem]

[0010] To achieve this object, the present invention includes a first invention relating to a film formation apparatus using magnetron sputtering, and a second invention relating to a film formation method using magnetron sputtering.

[0011] Among these, a first invention relating to a film formation apparatus using magnetron sputtering is suitable for forming an insulating coating on a workpiece and includes a vacuum chamber, a magnetron sputtering cathode, an earth shield, an exhaust means, an inert gas introduction means, a sputtering power supply means, a reactive gas introduction means, a bias power supply means, a cathode filament, a heating power supply means, an arc discharge power supply means, a heating power control means, and an anode filament. Specifically, the vacuum chamber is grounded, i.e., at ground potential. A magnetron sputtering cathode having a target that will be used as a material for the insulating reactive film is provided within the vacuum chamber. The workpiece is then placed within the vacuum chamber, specifically, positioned to face the target's roughly rectangular, planar sputtering surface. The earth shield is provided to surround the magnetron sputtering cathode, leaving only the target's sputtering surface exposed. The earth shield is also grounded, i.e., at ground potential. The exhaust means includes a vacuum pump. A vacuum pump evacuates the vacuum chamber through an exhaust port. An inert gas introducing means introduces an inert gas as a discharge gas into the vacuum chamber. A sputtering power supply means supplies sputtering power to the vacuum chamber (strictly speaking, the earth shield as the anode and the magnetron sputtering cathode as the cathode), with the vacuum chamber as the anode and the earth shield as the anode, respectively. This causes discharge of inert gas particles, generating magnetron plasma that adheres to the sputtering surface of the target. The magnetron plasma discharge mode is a high-voltage, low-current glow discharge. The magnetron plasma adheres to the sputtering surface of the target due to the action of a magnetic field formed in the vicinity of the sputtering surface by a magnetic field forming means provided in the magnetron sputtering cathode.

[0012] Particles of the inert gas in the magnetron plasma, particularly ions, collide with the sputtering surface of the target, knocking out particles constituting the target from the sputtering surface, i.e., sputtering. The sputtering area, which is the area to be sputtered, is limited to the sputtering surface of the target, i.e., the aforementioned earth shield is provided to ensure this. Furthermore, a reactive gas introduction means introduces a reactive gas, which is the material for the insulating coating, into the vacuum chamber. The reactive gas particles are decomposed by the magnetron plasma. The bias power supply means supplies a constant bias power with a predetermined composition to the vacuum chamber as the anode and the workpiece as the cathode. This accelerates the inert gas particles, reactive gas particles, and sputtered particles from the sputtering surface of the target toward the workpiece at a constant acceleration. In particular, the reactive gas particles and sputtered particles adhere to the surface of the workpiece and react with each other, forming an insulating coating, which is a reaction film composed of the reactive gas particles and sputtered particles, on the surface of the workpiece. In addition, the density of the insulating coating is improved by the bombardment of the surface of the workpiece by particles of the inert gas. Note that the predetermined component of the bias power is, for example, the average value or effective value of the bias voltage, which is the voltage component of the bias power.

[0013] Additionally, the cathode filament is a linear member that is disposed between the sputtering surface of the target and the workpiece in the vacuum chamber, extending along the longitudinal direction of the sputtering surface. The heating power supply supplies heating power to the cathode filament, causing it to heat and emit thermoelectrons. The arc discharge power supply supplies arc discharge power to both the vacuum chamber (strictly speaking, the earth shield as the anode) and the cathode filament as the cathode. The thermoelectrons emitted from the cathode filament are then accelerated toward the earth shield, where they collide with inert gas particles, reactive gas particles, and sputter particles. Because the aforementioned magnetic field is formed around the cathode filament, the electrons accelerated from the cathode filament toward the earth shield undergo a spiral motion due to the effect of the magnetic field. This increases the frequency with which thermions collide with inert gas particles, reactive gas particles, and sputter particles, inducing a low-voltage, high-current arc discharge around the cathode filament. In other words, in addition to the magnetron plasma generated by the glow discharge, an extremely high-density plasma generated by the arc discharge is generated around the cathode filament, i.e., between the sputtering surface of the target and the workpiece.

[0014] Therefore, sputtered particles sputtered from the sputtering surface of the target pass through a space of extremely high-density plasma on their way toward the workpiece. This activates the sputtered particles and efficiently ionizes them. Similarly, reactive gas particles are also activated and efficiently ionized. At the same time, inert gas particles are also activated and efficiently ionized. This improvement in ionization rate increases the number of ions incident on the surface of the workpiece, thereby increasing the hardness of the insulating coating formed on the surface of the workpiece. Furthermore, the mutual bonding force between the sputtered particles and the reactive gas particles is increased, thereby densifying the insulating coating. In addition, the bombardment action of the inert gas particles on the surface of the workpiece is enhanced, thereby further improving the density of the reactive film.

[0015] The heating power control means controls the heating power so that the current component of the arc discharge power, i.e., the arc discharge current, is kept constant while the voltage component of the arc discharge power, i.e., the arc discharge voltage, is kept constant, thereby stabilizing the density of the plasma generated by the arc discharge.

[0016] Furthermore, the anode filament is a linear member located near the earth shield in the vacuum chamber, parallel to the cathode filament. The anode filament is at ground potential or a positive potential relative to the ground potential. The anode filament glows red due to the inflow of electrons from the plasma generated by the discharge of inert gas particles, reactive gas particles, and sputtered particles. Strictly speaking, the anode filament is heated to a temperature high enough to evaporate any insulating coating that may have adhered to its surface (more specifically, the sputtered particles before they react with the reactive gas particles). The anode filament functions as the anode for both the glow discharge and the arc discharge. In particular, if the surface of the earth shield becomes covered with an insulating coating and the earth shield is no longer able to function as an anode, the anode filament functions as the anode in place of the earth shield. That is, even if an insulating coating adheres to the anode filament's surface, the insulating coating evaporates, thereby maintaining the anode function of the anode filament. This allows stable discharge to be maintained, and the film-forming process for forming the insulating film to be carried out stably.

[0017] When the anode filament is set to a positive potential relative to the ground potential, the value of the positive potential is preferably, for example, greater than 0 V and equal to or less than 30 V.

[0018] It is also desirable that the cathode filament and the anode filament are made of the same material.

[0019] Furthermore, the cathode filament and the anode filament may each be provided so as to extend in the vertical direction. In this case, the target is provided so that the longitudinal direction of its sputtering surface is aligned with the vertical direction. The upper end of the anode filament may be fixed to a support member as a fixed end, and the lower end of the anode filament may be left hanging down as a free end.

[0020] In addition, two anode filaments may be provided. In this case, the cathode filament is preferably provided at a position corresponding to the center of the sputtering surface in the short direction of the sputtering surface of the target. The two anode filaments are preferably provided so as to be symmetrical with respect to an imaginary plane. The imaginary plane here refers to a plane that includes the axis of the cathode filament and is perpendicular to the sputtering surface of the target.

[0021] Here, the earth shield has a flat surface that is roughly flush with the sputtered surface of the target. In this case, each of the two anode filaments is provided at a position corresponding to the edge of the sputtered surface closest to itself in the short direction of the sputtered surface of the target, or at a position 15 mm or less away from that position outward from the sputtered surface of the target, in other words, in the direction opposite to the aforementioned imaginary plane. In addition, it is desirable that each of the two anode filaments be provided at a position 5 mm or more but 30 mm or less away from the flat surface of the earth shield in the direction toward the sputtered surface of the target, in the direction perpendicular to the sputtered surface of the target.

[0022] Furthermore, the exhaust means may include a conductance valve. The conductance valve controls the effective exhaust speed at the exhaust port of the vacuum chamber. In this case, it is desirable to further provide a reactive gas flow rate control means. The reactive gas flow rate control means controls the flow rate of the reactive gas introduced into the vacuum chamber so that the pressure inside the vacuum chamber is constant while the flow rate of the inert gas introduced into the vacuum chamber, the sputtering power, and the effective exhaust speed at the exhaust port of the vacuum chamber are kept constant by the conductance valve. This maintains a constant sputtering rate (the number of sputtered particles per unit time and unit area, sometimes called the "sputter evaporation rate"; however, since it cannot be measured directly, it is typically expressed as the mass of particles sputtered per unit time (g / min)) on the sputtered surface of the target. This is extremely useful for improving the reproducibility of insulating coatings.

[0023] In the first invention, a plurality of units may be provided. The unit referred to here is a plasma generation source, so to speak, having a magnetron sputtering cathode, an earth shield, a sputtering power supply means, a cathode filament, a heating power supply means, an arc discharge power supply means, a heating power control means, and an anode filament. In other words, a plurality of units serving as plasma generation sources may be provided.

[0024] A second invention of the present invention, which relates to a film formation method using magnetron sputtering, includes a workpiece placement step, an evacuation step, an inert gas introduction step, a sputtering power supply step, a reactive gas introduction step, a bias power supply step, a heating power supply step, an arc discharge power supply step, a heating power control step, and an anode maintenance step. In the workpiece placement step, the workpiece is placed in a vacuum chamber provided with a magnetron sputtering cathode having a target serving as an insulating coating material, facing the approximately rectangular planar sputtering surface of the target. The vacuum chamber is grounded, i.e., at ground potential. An earth shield is provided around the magnetron sputtering cathode, with only the sputtering surface of the target exposed. This earth shield is also grounded, i.e., at ground potential. In the evacuation step, the vacuum chamber is evacuated by a vacuum pump through an exhaust port of the vacuum chamber. In the inert gas introduction step, an inert gas is introduced into the vacuum chamber as a discharge gas. In the sputtering power supply step, sputtering power is supplied to the vacuum chamber as the anode (strictly speaking, the earth shield as the anode) and the magnetron sputtering cathode as the cathode. This causes inert gas particles to discharge, generating magnetron plasma that adheres to the sputtering surface of the target. The magnetron plasma discharge mode is a high-voltage, low-current glow discharge. The magnetron plasma adheres to the sputtering surface of the target due to the action of a magnetic field formed in the vicinity of the sputtering surface by a magnetic field forming means provided in the magnetron sputtering cathode.

[0025] Particles of the inert gas in the magnetron plasma, particularly ions, collide with the sputtering surface of the target, knocking out particles constituting the target from the sputtering surface, i.e., sputtering. The sputtering region, which is the area to be sputtered, is limited to the sputtering surface of the target, i.e., the aforementioned earth shield is provided to ensure this. Furthermore, in the reactive gas introduction step, a reactive gas serving as the material for the insulating coating is introduced into the vacuum chamber. The reactive gas particles are decomposed by the magnetron plasma. Then, in the bias power supply step, a constant bias power with a predetermined composition is supplied to the vacuum chamber as the anode and the workpiece as the cathode. This accelerates the inert gas particles, reactive gas particles, and sputtered particles from the sputtering surface of the target toward the workpiece at a constant acceleration. In particular, the reactive gas particles and sputtered particles adhere to the surface of the workpiece and react with each other, forming an insulating coating, which is a reaction film composed of the reactive gas particles and sputtered particles, on the surface of the workpiece. In addition, the density of the insulating coating is improved by the bombardment of the surface of the workpiece by particles of the inert gas. Note that the predetermined component of the bias power is, for example, the average value or effective value of the bias voltage, which is the voltage component of the bias power.

[0026] In the heating power supply step, heating power is supplied to the cathode filament. The cathode filament is a linear member that is disposed between the sputtering surface of the target and the workpiece in the vacuum chamber, extending along the longitudinal direction of the sputtering surface. The cathode filament is heated by the heating power and emits thermoelectrons. In the arc discharge power supply step, the vacuum chamber serves as the anode, specifically the earth shield serves as the anode, and the cathode filament serves as the cathode, and arc discharge power is supplied to both. The thermoelectrons emitted from the cathode filament are then accelerated toward the earth shield, and collide with inert gas particles, reactive gas particles, and sputter particles. Because the aforementioned magnetic field is formed around the cathode filament, the electrons accelerated from the cathode filament toward the earth shield undergo a spiral motion due to the effect of the magnetic field. This increases the frequency with which the thermal electrons collide with the inert gas particles, reactive gas particles, and sputter particles, inducing a low-voltage, high-current arc discharge around the filament. In other words, in addition to the magnetron plasma generated by the glow discharge, an extremely high-density plasma generated by the arc discharge is generated around the cathode filament, i.e., between the sputtering surface of the target and the workpiece.

[0027] Therefore, sputtered particles sputtered from the sputtering surface of the target pass through a space of extremely high-density plasma on their way toward the workpiece. This activates the sputtered particles and efficiently ionizes them. Similarly, reactive gas particles are also activated and efficiently ionized. At the same time, inert gas particles are also activated and efficiently ionized. This improvement in ionization rate increases the number of ions incident on the surface of the workpiece, thereby increasing the hardness of the insulating coating formed on the surface of the workpiece. Furthermore, the mutual bonding force between the sputtered particles and the reactive gas particles is increased, thereby densifying the insulating coating. In addition, the bombardment action of the inert gas particles on the surface of the workpiece is enhanced, thereby further improving the density of the reactive film.

[0028] In the heating power control step, the heating power is controlled so that the current component of the arc discharge power, i.e., the arc discharge current, is kept constant while the voltage component of the arc discharge power, i.e., the arc discharge voltage, is kept constant, thereby stabilizing the density of the plasma generated by the arc discharge.

[0029] Furthermore, in the anode maintenance step, electrons in the plasma generated by the discharge of inert gas particles, reactive gas particles, and sputtered particles are introduced into the anode filament, causing the anode filament to glow red. Specifically, the anode filament is heated to a temperature sufficient to evaporate any insulating coating that may have adhered to the surface of the anode filament. The anode filament is a linear member disposed in the vacuum chamber near the earth shield and parallel to the cathode filament. The anode filament is also at ground potential or a positive potential relative to the earth potential. The anode filament functions as an anode for the two discharges, glow discharge and arc discharge, described above. In particular, when the surface of the earth shield is covered with an insulating coating and the earth shield is no longer able to function as an anode, the anode filament functions as an anode in place of the earth shield. In other words, even if an insulating coating adheres to the surface of the anode filament, the insulating coating evaporates, thereby maintaining the anode function of the anode filament. This allows stable discharge to be maintained, and the film-forming process for forming the insulating film to be carried out stably. [Effects of the Invention]

[0030] According to the present invention, the film formation process for forming an insulating film can be stably carried out, and as a result, a homogeneous insulating film can be formed. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a magnetron sputtering apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a top view of the inside of a magnetron sputtering apparatus according to an embodiment of the present invention. [Figure 3] FIG. 3 is a diagram showing a schematic configuration of a magnetron sputtering cathode in one embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the relative positions of some elements including a magnetron sputtering cathode in one embodiment of the present invention. [Figure 5] FIG. 5 is an enlarged view showing the relative positions of some elements including a magnetron sputtering cathode in one embodiment of the present invention. [Figure 6] FIG. 6 is a photographed image of a portion including a magnetron sputtering cathode in one embodiment of the present invention. [Figure 7] FIG. 7 is a photographed image of a portion including a magnetron sputtering cathode during a film formation process in one embodiment of the present invention. [Figure 8] FIG. 8 is a diagram showing experimental results in one embodiment of the present invention. [Figure 9] FIG. 9 is a diagram showing another experimental result in an embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing the results of yet another experiment in an embodiment of the present invention in comparison with the results of an experiment in the prior art. [Figure 11] FIG. 11 is a diagram showing the results of yet another experiment in an embodiment of the present invention in comparison with the results of an experiment in the prior art. [Figure 12] FIG. 12 is a diagram showing an expanded example of an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] An embodiment of the present invention will be described with reference to FIGS.

[0033] As shown in FIGS. 1 and 2 , a magnetron sputtering apparatus 10 according to this embodiment includes a generally cylindrical vacuum chamber 12 with both ends closed. The vacuum chamber 12 is installed with both ends of the generally cylindrical shape facing up and down, i.e., with the central axis Xa of the cylinder extending vertically. The inner diameter of the vacuum chamber 12 is, for example, approximately 1300 mm, and the height within the vacuum chamber 12 is, for example, approximately 1100 mm. The shape and dimensions of the vacuum chamber 12 are merely exemplary and are determined appropriately depending on various factors, such as the size, shape, and number of workpieces 100 (described below). The vacuum chamber 12 itself is made of a highly corrosion-resistant and heat-resistant metal, such as stainless steel such as SUS304, and its walls are grounded, i.e., the potential of the walls is set to the ground potential, which is a reference potential.

[0034] An exhaust port 14 is provided at an appropriate position on the wall of the vacuum chamber 12, for example, at an appropriate position on the wall forming the side surface. The exhaust port 14 is connected to a vacuum pump 18 via exhaust piping 16 outside the vacuum chamber 12, and more precisely, is connected to an intake port (not shown) of the vacuum pump 18. The vacuum pump 18 may be, for example, a diffusion pump, a turbomolecular pump, or a cryopump, but is not limited to these. In addition, in FIG. 2, some elements, including the exhaust port 14, are not shown for ease of viewing.

[0035] A main valve, or on-off valve 20, serving as on-off means for opening and closing the inside of the exhaust pipe 16 is provided midway along the exhaust pipe 16. Also provided midway along the exhaust pipe 16 is a conductance valve 22 for controlling the effective pumping speed at the exhaust port 14 of the vacuum chamber 12 by the vacuum pump 18. This conductance valve 22 cooperates with the vacuum pump 18 to form an exhaust means. Although not shown in detail, the conductance valve 22 has a plurality of elongated, plate-like blade members arranged in parallel like blinds, and the angle θ of these blade members controls the effective pumping speed at the exhaust port 14 of the vacuum chamber 12. For example, the smaller the angle θ of the conductance valve 22 (blade member), the greater the conductance, and when the angle θ is 0 degrees, the conductance valve is fully open. Conversely, the larger the angle θ of the conductance valve 22, the smaller the conductance, and when the angle θ is 90 degrees, the conductance valve 22 is fully closed. This configuration of the conductance valve 22 is an example and is not limiting.

[0036] Furthermore, a magnetron sputtering cathode 24 is provided at an appropriate position inside the wall forming the side surface of vacuum chamber 12 (at the right side in FIGS. 1 and 2), while being electrically insulated from the wall of vacuum chamber 12. Referring also to FIG. 3, magnetron sputtering cathode 24 has a target 242 having a generally rectangular flat plate shape that serves as a coating material, and a magnet unit 244 provided on the back side, which is one main surface, of target 242. Magnet unit 244 has a permanent magnet 246 as an example of magnetic field generating means, and a housing 248 that houses permanent magnet 246. The permanent magnet 246 has, for example, an S-pole 246a as one magnetic pole in a roughly rectangular frame shape that is provided along the periphery of the target 242 while being in close contact with the back surface of the target 242, and an N-pole 246b as the other magnetic pole that is in a roughly elongated protrusion shape (roughly rectangular parallelepiped shape) that is provided inside the S-pole 246a and extends along the longitudinal direction of the target 242 while being in close contact with the back surface of the target 242. The dimensions of the target 242 are, for example, 690 mm in the longitudinal direction (length dimension), 127 mm in the lateral direction (width dimension), and 8 mm in the thickness direction (thickness dimension). A roughly rectangular groove-shaped gap 246c is provided between the S-pole 246a and the N-pole 246b of the permanent magnet 246. The housing 248 is provided with an appropriate water-cooling mechanism (not shown) as cooling means for cooling the entire magnetron sputtering cathode 24, including the housing 248.

[0037] The magnetron sputtering cathode 24 is disposed such that the roughly rectangular, planar sputtering surface, which is the other main surface (front surface) of the target 242, faces the central axis Xa of the vacuum chamber 12, and the longitudinal direction of the target 242 is aligned along the extension direction of the central axis Xa of the vacuum chamber 12, i.e., along the vertical direction. In addition, the magnetron sputtering cathode 24 is disposed such that the center of the sputtering surface of the target 242 in the lateral direction faces the central axis Xa of the vacuum chamber 12, as shown in FIG.

[0038] The magnetron sputtering cathode 24 is covered by the earth shield 26, except for (only) the surface to be sputtered of the target 242. In other words, the earth shield 26 is provided to surround the outer periphery of the magnetron sputtering cathode 24, leaving (only) the surface to be sputtered of the target 242 of the magnetron sputtering cathode 24 exposed. The earth shield 26 is made of a metal with high corrosion resistance and heat resistance, such as stainless steel such as SUS304. The earth shield 26 is electrically insulated from the magnetron sputtering cathode 24, but is electrically and mechanically connected to the wall of the vacuum chamber 12 and is directly grounded (separate from the vacuum chamber 12) as shown in FIG. 1 to more reliably maintain its own potential at ground potential.

[0039] Explaining this in more detail with reference to FIG. 4 , the earth shield 26 has a generally rectangular cylindrical portion 262 that surrounds the outer periphery of the magnetron sputtering cathode 24, and a generally flange-shaped flange portion 264 that extends outward from one edge of the rectangular cylindrical portion 262 (the edge on the sputtering surface side of the target 242). The flange portion 264 has a flat portion 264a that is generally flush with the sputtering surface of the target 242. The extension dimension of the flange portion 264, in other words, the extension dimension Ds of the flat portion 264a, is, for example, 30 mm. An appropriate gap 266 is provided between the inner peripheral surface (inner surface) of the rectangular cylindrical portion 262 and the outer peripheral surface (outer surface) of the magnetron sputtering cathode 24. This gap 266 is called a “dark space,” and its dimension Dd is, for example, approximately 2 mm.

[0040] 2, the portion 12a of the wall of the vacuum chamber 12 where the magnetron sputtering cathode 24 and the earth shield 26 are provided has a structure suitable for providing the magnetron sputtering cathode 24 and the earth shield 26. Taking into consideration the ease of operation during maintenance of the magnetron sputtering cathode 24, including replacement of the target 242, this portion 12a is preferably made openable and closable like a sliding door or a hinged door.

[0041] Referring again to FIG. 1 , the magnetron sputtering cathode 24 is connected to a sputtering power supply 28, an example of a sputtering power supply means, outside the vacuum chamber 12. This sputtering power supply 28 supplies sputtering power Es to both the vacuum chamber 12 (strictly speaking, the earth shield 26 as the anode) and the magnetron sputtering cathode 24 as the cathode. The sputtering power Es is a so-called asymmetric bipolar pulsed power in which its voltage component, the sputtering voltage (also referred to as the “target voltage”) Vs, alternates between a high level value of 0 V or higher relative to the ground potential and a low level value of a negative potential relative to the ground potential. In other words, the sputtering power supply 28 is a pulsed power supply that generates asymmetric bipolar pulsed power as the sputtering power Es. The high level value of the sputtering voltage Vs can be set arbitrarily within a predetermined range, and here, for example, is set to +100 V relative to the ground potential. Meanwhile, the low-level value of the sputtering voltage Vs can also be set arbitrarily within a predetermined range, and the average value (DC equivalent value) of the sputtering voltage Vs is determined by this low-level value. The frequency of the sputtering voltage Vs can also be set arbitrarily within a predetermined range, and is set to, for example, 100 kHz here. Furthermore, the duty ratio of the sputtering voltage Vs (the ratio of the period during which the sputtering voltage Vs is at its high-level value in one cycle of the sputtering voltage Vs) can also be set arbitrarily within a predetermined range, and is set to, for example, 20% here.

[0042] Additionally, a cathode filament 30 serving as a thermoelectron emitting means is provided in front of the magnetron sputtering cathode 24, more specifically in front of the sputtering surface of the target 242. This cathode filament 30 is a linear member made of tungsten (W) with a diameter of, for example, approximately 1 mm. Note that the cathode filament 30 is not limited to being made of tungsten, and may also be made of other high-melting-point metals such as molybdenum (Mo), tantalum (Ta), or carbon (C).

[0043] Referring again to Figure 4, particularly Figure 4(a), when viewed from the horizontal side opposite the direction in which the magnetron sputtering cathode 24 is disposed, for example, from the side of the central axis Xa of the vacuum chamber 12, the cathode filament 30 extends linearly along the vertical direction through the center of the short side of the sputtering surface of the target 242, i.e., along the longitudinal direction of the target 242, in other words, parallel to the sputtering surface of the target 242. Also, as shown in Figures 4(b) and 4(c), the cathode filament 30 is disposed with an appropriate distance Dcv between it and the sputtering surface of the target 242. If this distance Dcv is excessively small, for example, there is a risk that the cathode filament 30 will come into contact with the sputtering surface of the target 242 or the earth shield 26 due to vibration or the like, which would be extremely inconvenient. On the other hand, if the distance Dcv is excessively large, the effect of the magnetic field around the cathode filament 30 by the magnet unit 244 (permanent magnet 246) described above will be weak, which will be inconvenient for inducing an arc discharge, which will be described later. For these reasons, the distance Dcv is suitably about 5 mm to 50 mm, for example, 25 mm. The length of the cathode filament 30 is equal to or longer than the length of the target 242, and more precisely, equal to or longer than the length of an erosion region 242a of the target 242, which will be described later, for example, 750 mm.

[0044] 1, both ends of the cathode filament 30 are connected to a heating power supply device 32, which is an example of a heating power supply means, outside the vacuum chamber 12. The cathode filament 30 is supplied with AC cathode power Ec as heating power from the heating power supply device 32. This heats the cathode filament 30 to 2000°C or higher, causing thermions to be emitted from the cathode filament 30. Note that the cathode power Ec is not limited to AC power, and may be DC power.

[0045] Furthermore, one end of the cathode filament 30, for example, the upper end, is connected outside the vacuum chamber 12 to an arc discharge power supply 34, which serves as an example of an arc discharge power supply means. The arc discharge power supply 34 supplies the cathode filament 30 with arc discharge power Ed, which is DC power at a negative potential relative to the ground potential. In other words, the vacuum chamber 12 serves as the anode, or more precisely, the earth shield 26 serves as the anode, and the cathode filament 30 serves as the cathode, and arc discharge power Ed is supplied to both of them. The arc discharge power supply 34 is, for example, a constant voltage power supply, and its maximum output voltage, i.e., the maximum value of the arc discharge voltage Vd, which is the voltage component of the arc discharge power Ed, is, for example, 100 V.

[0046] A current detector 36 serving as an arc discharge current detection means is provided between the arc discharge power supply device 34 and ground. This current detector 36 detects the arc discharge current Id, which is a current component of the arc discharge power Ed. The value of the arc discharge current Id detected by the current detector 36 is provided to a heating controller 38 serving as an example of heating power control means.

[0047] The heating controller 38 controls the heating power supply device 32 so that the value of the arc discharge current Id detected by the current detector 36 becomes constant, that is, so that the arc discharge current Id becomes constant, and more specifically, controls the cathode power Ec via the heating power supply device 32. This allows the heating temperature of the cathode filament 30, that is, the amount of thermoelectrons emitted by the cathode filament 30, to be appropriately adjusted. In other words, the amount of thermoelectrons emitted by the cathode filament 30 is automatically controlled (feedback controlled) using the arc discharge current Id as a parameter.

[0048] Focusing on the inside of the position where the cathode filament 30 is provided in the vacuum chamber 12, multiple workpieces 100 are arranged within the vacuum chamber 12. Specifically, the workpieces 100 are arranged at equal intervals along the circumferential direction of a circle centered on the central axis Xa of the vacuum chamber 12. Each workpiece 100 has, for example, an elongated, approximately cylindrical or columnar shape, and is held by a holder 40 serving as a holding means so as to extend vertically, i.e., in a direction along the central axis Xa of the vacuum chamber 12. Each holder 40 is coupled via a gear mechanism 42 to the vicinity of the periphery of a disk-shaped revolution table 44. The center of the revolution table 44 is located on the central axis Xa of the vacuum chamber 12, and one end of a rotation shaft 46 extending along the central axis Xa of the vacuum chamber 12 is fixed to the center of the revolution table 44. The other end of the rotary shaft 46 is connected to a shaft 48a of a motor 48 serving as a rotary drive means outside the vacuum chamber 12.

[0049] That is, when the motor 48 is driven and the shaft 48a of the motor 48 rotates in the direction indicated by the arrow 200 in FIG. 1, the revolving table 44 rotates in the same direction, i.e., in the direction indicated by the arrow 200 in FIG. 2. Accordingly, each workpiece 100 rotates about the central axis Xa of the vacuum chamber 12, or in other words, revolves. At the same time, due to the rotational drive force transmission action of each gear mechanism 42, each holder 40 rotates about a vertical line Xb passing through the holder 40, for example, in the direction indicated by the arrow 202 in FIGS. 1 and 2. Then, as the holder 40 rotates, the workpiece 100 also rotates in the same direction, or in other words, spins on its own axis. The revolution path diameter (PCD) of the workpiece 100 is, for example, approximately 600 mm. The revolution speed of the workpiece 100 (the rotation speed of the revolving table 44) is, for example, 0.5 rpm to 1 rpm. In contrast, the rotation speed of the workpieces 100 (the rotation speed of the holder 40 itself) is, for example, 30 rpm to 60 rpm, that is, 60 times the revolution speed. 1 and 2 show an example in which the number of workpieces 100 (holders 40 and gear mechanisms 42) is 12, but the number of workpieces 100 is not limited to this. Furthermore, the shape of the workpieces 100 is not limited to the aforementioned elongated, approximately columnar or approximately cylindrical shape.

[0050] Additionally, substrate bias power Eb is supplied to each workpiece 100 from a bias power supply device 50, which is an example of a bias power supply means and is located outside the vacuum chamber 12, via the holder 40, gear mechanism 42, revolving table 44, and rotation shaft 46. In other words, the vacuum chamber 12 serves as the anode, and each workpiece 100 serves as the cathode, and substrate bias power Eb is supplied to both. The substrate bias power Eb is an asymmetric bipolar pulse power in which its voltage component, a substrate bias voltage Vb, alternates between a high level value of a positive potential with respect to the ground potential and a low level value of a negative potential with respect to the ground potential. In other words, the bias power supply device 50 is a pulse power supply device that generates asymmetric bipolar pulse power as the substrate bias power Eb. The high level value of the substrate bias voltage Vb is constant, e.g., +37 V with respect to the ground potential. On the other hand, the low-level value of the substrate bias voltage Vb can be set arbitrarily within a predetermined range, and the average value (DC equivalent value) of the substrate bias voltage Vb is determined by this low-level value. Furthermore, the frequency of the substrate bias power Eb can also be set arbitrarily within a range of, for example, 50 kHz to 250 kHz. The duty ratio of the substrate bias power Eb (the ratio of the period during which the substrate bias voltage Vb is at a high-level value in one cycle of the substrate bias voltage Vb) can also be set arbitrarily within a predetermined range. Here, the frequency of the substrate bias power Eb is set to, for example, 100 kHz, and the duty ratio is set to, for example, 20%. Note that the bias power supply device 50 may be configured so that the effective value of the substrate bias voltage Vb is determined, rather than the average value of the substrate bias voltage Vb.

[0051] Furthermore, a carbon heater 52, for example, is provided as a temperature control means at an appropriate position inside the wall forming the side surface of the vacuum chamber 12, but outward from the revolution path of each of the workpieces 100, 100, ..., for example, on the opposite side of the central axis Xa of the vacuum chamber 12 from the position where the magnetron sputtering cathode 24 is provided (the left side position in Figures 1 and 2). This carbon heater 52 is connected to a heater heating power supply device (not shown) outside the vacuum chamber 12. The carbon heater 52 receives a supply of DC or AC heater heating power from the heater heating power supply device and generates heat, thereby heating the inside of the vacuum chamber 12, and in particular the workpieces 100, 100, ... As shown in FIG. 2, the portion 12b of the wall of the vacuum chamber 12 where the carbon heater 52 is provided is also structured appropriately for providing the carbon heater 52, similar to the portion 12a where the magnetron sputtering cathode 24 and earth shield 26 are provided.

[0052] 1, a gas inlet 54 for introducing various gases, such as an inert gas, into the vacuum chamber 12 is provided at an appropriate position within the vacuum chamber 12, preferably near the cathode filament 30. A gas inlet pipe 56 is connected to the gas inlet 54 outside the vacuum chamber 12, and a plurality of branch pipes 58 and 60, two in this example, are connected to the gas inlet pipe 56.

[0053] One branch pipe 58 is a pipe for introducing an inert gas as a discharge gas into the vacuum chamber 12, and is connected to a supply source (not shown) of the inert gas. This branch pipe 58 for introducing the inert gas is provided with an on-off valve 58a as an on-off means for opening and closing the branch pipe 58, and a mass flow controller 58b as a flow rate control means for controlling the flow rate Qd of the inert gas flowing through the branch pipe 58. The branch pipe 58 including the on-off valve 58a and the mass flow controller 58b cooperates with the gas introduction pipe 56 to constitute an example of an inert gas introduction means. The inert gas may be, for example, argon (Ar) gas.

[0054] The other branch pipe 60 is a pipe for introducing a reactive gas, which serves as a material for a coating, particularly a reactive film, into the vacuum chamber 12. The reactive gas is supplied from a reactive gas supply source (not shown). This branch pipe 60 for introducing the reactive gas is also provided with an on-off valve 60a as an on-off means for opening and closing the branch pipe 60 and a mass flow controller 60b as a flow rate control means for controlling the flow rate Qr of the reactive gas flowing through the branch pipe 60. The branch pipe 60 including the on-off valve 60a and the mass flow controller 60b, in cooperation with the gas introduction pipe 56, constitutes an example of a reactive gas introduction means. An appropriate gas is used as the reactive gas depending on the type of reactive film to be formed. For example, when a nitride film is to be formed as the reactive film, nitrogen (N) gas is used as the reactive gas. When a carbonized film is to be formed as the reactive film, a hydrocarbon gas such as acetylene (CH) is used as the reactive gas. When an oxide film is to be formed as the reactive film, oxygen (O) gas is used as the reactive gas.

[0055] Additionally, a pressure gauge 62 is provided at an appropriate position within the vacuum chamber 12, for example, at an appropriate position in the upper part of the vacuum chamber 12, so that a gauge portion (measurement portion) 62a of the pressure gauge 62 is disposed therein. The pressure gauge 62 is a pressure measurement means for measuring the pressure within the vacuum chamber 12, specifically, the pressure P at the position where the gauge portion 62a is disposed. The pressure P measured by the pressure gauge 62 is provided to a gas flow controller 64, an example of a reactive gas flow control means, located outside the vacuum chamber 12. Note that the pressure gauge 62 may be, for example, a diaphragm vacuum gauge capable of measuring absolute pressure with relatively high accuracy and high resolution. The position where the gauge portion 62a is disposed is not limited to the upper part of the vacuum chamber 12, and may be any position that is less affected by the plasma 300, which will be described later. The main body of the pressure gauge 62 is provided outside the vacuum chamber 12.

[0056] The gas flow controller 64 controls the mass flow controller 60b for introducing the reactive gas so that the pressure P measured by the pressure gauge 62 becomes constant, that is, so that the pressure P becomes constant, as will be described later, and more specifically, controls the flow rate Qr of the reactive gas introduced into the vacuum chamber 12 via the mass flow controller 60b. In other words, the flow rate Qr of the reactive gas is automatically controlled (feedback controlled) using the pressure P inside the vacuum chamber 12 as a parameter. 。

[0057] Although detailed explanation including illustrations is omitted, a shutter is provided between the cathode filament 30 and the workpiece 100 located closest to the cathode filament 30 (i.e., the portion of the workpiece 100 in its revolution path that is closest to the cathode filament 30). This shutter appropriately transitions between an open state that exposes the sputtering surface of the target 242 of the magnetron sputtering cathode 24 to the space in which the workpiece 100 is placed, and a closed state that shields it from the space.

[0058] Furthermore, two anode filaments 70, 70 serving as anode maintenance means are provided near the earth shield 26, more specifically near the flat portion 264a. Each of these anode filaments 70, 70 is made of the same material as the cathode filament 30, i.e., a linear member made of tungsten with a diameter of approximately 1 mm, for example. While each anode filament 70 may be made of a different material from the cathode filament 30, it is desirable to form it from the same material as the cathode filament 30 from the standpoints of cost and management.

[0059] Referring again to Figure 4, particularly Figure 4(a), when viewed from the central axis Xa side of the vacuum chamber 12, the anode filaments 70, 70 are provided on both the left and right sides of the cathode filament 30, sandwiching the cathode filament 30 therebetween; more specifically, they are provided in front of the left and right portions of the flat portion 264a of the earth shield 26. Also referring to Figures 4(b) and 4(c), each of the anode filaments 70, 70 is provided so as to extend linearly in parallel with the cathode filament 30, that is, in the vertical direction. The anode filaments 70, 70 are provided so as to be plane-symmetrical with respect to a virtual plane (not shown) that includes the axis of the cathode filament 30 and is perpendicular to the sputtering surface of the target 242.

[0060] 5, each anode filament 70 is provided at a predetermined distance Dap in the short direction of the sputtered surface of the target 242 from a position corresponding to the edge of the sputtered surface closest to itself outward from the sputtered surface, in other words, in the direction opposite to the imaginary plane. In the direction perpendicular to the sputtered surface of the target 242, in other words, in the direction perpendicular to the flat portion 264a of the earth shield 26, each anode filament 70 is provided at a predetermined distance Dav from the flat portion 264a in the direction in which the sputtered surface of the target 242 is facing, that is, upward in FIG.

[0061] As will be described later, each anode filament 70 functions as an anode for two types of discharge, glow discharge and arc discharge, and the distances Dap and Dav referred to here are appropriately set, or optimized, so to speak, to ensure that it can function as an anode. For example, the distance Dap in the short-side direction of the sputtering surface of the target 242 is appropriately about 0 mm to 15 mm. That is, the distance Dap may be 0 mm. In this case, each anode filament 70 is provided at a position corresponding to the edge of the sputtering surface in the short-side direction of the sputtering surface of the target 242, that is, directly above the edge of the sputtering surface in FIG. 5. In extreme cases, each anode filament 70 may be provided at a position corresponding to the inside of the edge of the sputtering surface of the target 242 in the short direction of the sputtering surface, i.e., in front of the sputtering surface. However, if this is done, each anode filament 70 will get in the way when cleaning the sputtering surface of the target 242 (the sputtering surface of the target 242 is generally cleaned after each film formation process, that is, for each batch) or during maintenance such as when replacing the target 242, impeding the workability of the maintenance. Furthermore, if the distance Dap is excessively large, the effect of the magnetic field generated by the magnet unit 244 (permanent magnet 246) around each anode filament 70 will be weak, and the anode filament 70 will no longer function as an anode. For these reasons, the distance Dap is preferably approximately 0 mm to 15 mm, and is set to, for example, 5 mm.

[0062] On the other hand, the distance Dav in the direction perpendicular to the sputtering surface of the target 242 is set to approximately 5 mm to 30 mm. For example, if this distance Dav is excessively small, there is a risk that each anode filament 70 may come into contact with the flat portion 264a of the earth shield 26 due to vibration, which would be extremely inconvenient. Furthermore, if the distance Dav is excessively large, the magnetic field generated by the magnet unit 244 (permanent magnet 246) around each anode filament 70 will be weak, preventing it from functioning as an anode. For these reasons, the distance Dav is preferably set to approximately 5 mm to 30 mm, for example, 10 mm. As mentioned above, considering that the distance Dcv from the sputtering surface of the target 242 to the cathode filament 30 in the direction perpendicular to the sputtering surface is preferably set to approximately 5 mm to 50 mm, there may be cases in which the distance Dav from the flat portion 264a of the earth shield 26 to each anode filament 70 in the same direction is greater than the distance Dcv. 5, for example, there may be cases where each anode filament 70 is located higher than the cathode filament 30. Even in such a positional relationship, there is no particular problem as long as the distance Dav in the direction perpendicular to the sputtering surface of the target 242 is within a predetermined range of 5 mm to 30 mm.

[0063] Referring again to the cathode filament 30, the cathode filament 30 is provided at a position corresponding to the center of the sputtering surface in the short-side direction of the sputtering surface of the target 242. Therefore, as shown in Fig. 5, the distances Dcp from both ends of the sputtering surface to the cathode filament 30 in the short-side direction of the sputtering surface of the target 242 are the same. In addition, as described above, the dimension Dd of the dark space 266 is, for example, about 2 mm, and the reason for setting such a small value is to prevent plasma 300, which will be described later, from entering the dark space 266.

[0064] Figure 6 shows an image of a portion including the magnetron sputtering cathode 24, taken from diagonally in front of the sputtering surface of the target 242. As shown in Figure 6, both ends of the cathode filament 30 are fixed to appropriate support members 30a and 30b. Although it is difficult to see from Figure 6, the lower support member 30b is provided with a tensioning mechanism, more specifically, an appropriate weight, as tensioning means for applying an appropriate tension to the cathode filament 30 to maintain the straight state of the cathode filament 30.

[0065] In contrast, the upper end of each anode filament 70 is fixed to an appropriate support member 70a as a fixed end, while the lower end hangs down as a free end. Therefore, each anode filament 70 maintains a linearly extended state due to its own weight. To prevent swinging, each anode filament 70 is loosely restrained by relay members 70b at appropriate locations, for example, at approximately the center of the anode filament 70 in the extension direction and at a location near the lower end. Although it is difficult to see from FIG. 6 , each relay member 70b has an insertion hole with a diameter slightly larger than the diameter of the anode filament 70, for example, approximately 1.5 mm. Inserting the anode filament 70 through this insertion hole gently restrains the anode filament 70, thereby preventing swinging of the anode filament 70. Each relay member 70b is electrically insulated from other elements, such as the vacuum chamber 12, and is at a so-called floating potential. The length of each anode filament 70 is approximately the same as the length of the target 242, for example, 700 mm.

[0066] Referring again to FIG. 1 , the upper end of each anode filament 70 is connected outside the vacuum chamber 12 to an anode filament power supply 74 serving as an anode filament power supply via a reactor 72 serving as noise reduction means. The anode filament power supply 74 supplies anode filament power Eaf to the vacuum chamber 12 (strictly speaking, the earth shield 26 serving as the cathode) and the anode filament 70 serving as the anode. The anode filament power Eaf is a positive DC power with respect to the ground potential, and its voltage component, the anode filament voltage Vaf, can be set arbitrarily within a predetermined range above 0 V. The reactor 72 is provided to reduce the influence of pulse noise caused by the sputtering power Es, which is the asymmetric bipolar pulse power output from the sputtering power supply 28.

[0067] The reactor 72 is common to each of the anode filaments 70, 70, and the anode filament power supply device 74 is also common to each of the anode filaments 70, 70. That is, each of the anode filaments 70, 70 is connected to the anode filament power supply device 74 common to each of the anode filaments 70, 70 (i.e., one) via the reactor 72 common to each of the anode filaments 70, 70. Furthermore, when the anode filament voltage Vaf is set to 0 V, that is, when the anode filament voltage Vaf is set by the anode filament power supply device 74 so that it becomes 0 V, each of the anode filaments 70, 70 becomes the ground potential.

[0068] The magnetron sputtering apparatus 10 configured as described above can form various reactive films on the surface of the workpiece 100, and can stably perform film formation processing for forming insulating films in particular. For example, the formation of an aluminum nitride (AlN) film as the insulating film will be described. In this case, aluminum with a purity of 4N or higher is used as the target 242. Additionally, nitrogen gas with a purity of 5N or higher is used as the reactive gas.

[0069] Then, first, the workpiece 100 is placed in the vacuum chamber 12, that is, attached to the holder 40. Then, the inside of the vacuum chamber 12 is vacuumed by the vacuum pump 18 to a pressure of 2×10 -3 The air is evacuated until a pressure P of about Pa is reached, and so-called vacuuming is performed. Thereafter, motor 48 is driven, and rotation and revolution of workpiece 100 begin. At the same time, heater heating power is supplied to carbon heater 52, and workpiece 100 is heated to about 150°C. As a result, impurity gases contained in workpiece 100 are discharged, and so-called degassing is performed.

[0070] After this degassing process is performed for a predetermined time (e.g., about 30 minutes to 1 hour), the supply of heater heating power to the carbon heater 52 is stopped, and then, a discharge cleaning process is performed. In this discharge cleaning process, cathode power Ec is supplied to the cathode filament 30. In response to this, the cathode filament 30 is heated and thermoelectrons are emitted from the cathode filament 30. At the same time, arc discharge power Ed is supplied to the cathode filament 30. That is, the earth shield 26 serves as the anode, and the cathode filament 30 serves as the cathode, and arc discharge power Ed is supplied to both. As a result, thermoelectrons emitted from the cathode filament 30, which is the cathode, are accelerated toward the earth shield 26, which is the anode, particularly toward the flat portion 264a of the earth shield 26. In this state, argon gas is introduced into the vacuum chamber 12. The accelerated thermoelectrons then collide with argon gas particles, and the argon gas particles are ionized by the impact, generating plasma 300.

[0071] Here, a magnetic field is formed by the permanent magnet 246 described above in the vicinity of the sputtering surface of the target 242, including the periphery of the cathode filament 30, and the thermoelectrons accelerated from the cathode filament 30 toward the earth shield 26 undergo a spiral motion due to the effect of this magnetic field. As a result, the frequency with which the thermoelectrons collide with argon gas particles increases, thereby increasing the density of the plasma 300. The discharge mode of such plasma 300 is a low-voltage, high-current arc discharge.

[0072] Arc discharge can be induced even when the pressure P inside the vacuum chamber 12 is in the range of 0.01 Pa to 1 Pa, that is, even when the pressure P is relatively low. Furthermore, the arc discharge power Ed is kept constant; more specifically, the arc discharge voltage Vd, which is the voltage component of the arc discharge power Ed, is kept constant. In this state, the cathode power Ec is controlled so that the arc discharge current Id, which is the current component of the arc discharge power Ed, becomes constant; that is, the amount of thermoelectrons emitted from the cathode filament 30 is controlled. This stabilizes the density of plasma due to the arc discharge.

[0073] While the plasma 300 is being generated by this arc discharge, a substrate bias power Eb is supplied to the workpiece 100. That is, the vacuum chamber 12 serves as the anode, and the workpiece 100 serves as the cathode, and the substrate bias power Eb is supplied to both. Then, argon particles in the plasma 300, particularly argon ions, are actively incident on the surface of the workpiece 100. This impact removes impurities from the surface of the workpiece 100, thereby performing a so-called discharge cleaning process. Note that, since the workpiece 100 rotates and revolves as described above, the discharge cleaning process is performed while the workpiece 100 is exposed to the plasma 300 during this rotation and revolution. In other words, the discharge cleaning process is performed on the workpiece 100 in a simple manner.

[0074] After this discharge cleaning process is performed for a predetermined time (e.g., about 30 minutes), a film formation process is performed to form an aluminum nitride film. To this end, sputtering power Es is supplied to magnetron sputtering cathode 24. Specifically, sputtering power Es is supplied to both earth shield 26, which serves as the anode, and magnetron sputtering cathode 24, which serves as the cathode. Argon ions in plasma 300 then collide with the sputtering surface of target 242 of magnetron sputtering cathode 24, knocking aluminum particles off the sputtering surface of target 242, i.e., sputtering. The sputtering region, which is the area to be sputtered, is limited to the sputtering surface of target 242; in other words, the earth shield 26 is positioned to limit this. Furthermore, nitrogen gas is introduced into vacuum chamber 12 as a reactive gas. The nitrogen gas particles are decomposed by plasma 300.

[0075] Aluminum particles as sputtered particles sputtered from the sputtering surface of the target 242 are accelerated toward the workpiece 100 to which the substrate bias power Eb is supplied. At the same time, particles of nitrogen gas decomposed by the plasma 300 are also accelerated toward the workpiece 100. These aluminum particles and nitrogen particles adhere to the surface of the workpiece 100 and react with each other, forming an aluminum nitride film, which is an insulating coating composed of aluminum particles and nitrogen particles, on the surface of the workpiece 100. Furthermore, argon ions in the plasma 300 are also accelerated toward the workpiece 100. The bombardment action of these argon ions on the surface of the workpiece 100 improves the density of the aluminum nitride film formed on the surface of the workpiece 100.

[0076] In this film formation process, the supply of sputtering power Es also causes argon gas particles to discharge, inducing magnetron plasma due to high-voltage, low-current glow discharge. That is, plasma 300 includes (combines) magnetron plasma due to glow discharge in addition to the arc discharge described above. This magnetron plasma due to glow discharge is generated so that it adheres to the sputtering surface of target 242 due to the action of the magnetic field created by permanent magnet 246 described above.

[0077] The aluminum particles, nitrogen particles, and argon particles then pass through the extremely high-density plasma 300 on their way toward the workpiece 100. This activates the aluminum particles, nitrogen particles, and argon particles, resulting in more efficient ionization. This improvement in ionization rate increases the number of ions incident on the surface of the workpiece 100, thereby increasing the hardness of the aluminum nitride film formed on the surface of the workpiece 100. Furthermore, the mutual bonding force between the aluminum particles and the nitrogen particles increases, resulting in a densified aluminum nitride film. Furthermore, the bombardment effect of argon ions on the surface of the workpiece is enhanced, further improving the density of the reaction film.

[0078] In this film formation process, similarly to the discharge cleaning process described above, the workpiece 100 is subjected to the film formation process while it is exposed to the plasma 300 during its rotation and revolution. That is, the film formation process is simply performed on the workpiece 100. Furthermore, the pressure P in the vacuum chamber 12 during the film formation process is controlled within a range of, for example, 0.1 Pa to 1 Pa.

[0079] 4, focusing on the sputtering surface of the target 242, the density of the plasma 300 is higher in a region near the sputtering surface where the plasma 300 is generated, the region following the gap 246c of the permanent magnets 246. Therefore, the region of the sputtering surface of the target 242 where the density of the plasma 300 is higher, that is, the region following the gap 246c of the permanent magnets 246, is more efficiently (concentratedly) sputtered. As a result, sputtering marks in the shape of a roughly rectangular loop (or an oval loop) following the gap 246c of the permanent magnets 246 appear on the sputtering surface of the target 242, forming a so-called erosion region 242a.

[0080] After this film formation process is performed for a predetermined time (the time required to form an aluminum nitride film of a predetermined thickness), the introduction of argon gas and nitrogen gas into the vacuum chamber 12 is stopped. At the same time, the supply of sputtering power Es to the magnetron sputtering cathode 24 is stopped, and the supply of cathode power Ec and arc discharge power Ed to the cathode filament 30 is stopped. This causes the plasma 300 to disappear. Furthermore, the supply of substrate bias power Eb to the workpiece 100 is stopped. Then, with the vacuum chamber 12 maintained at a high vacuum by the vacuum pump 18, the vacuum chamber 12 is allowed to cool to a predetermined temperature (e.g., 150°C), i.e., an appropriate cooling period is allowed. Then, the motor 48 is stopped, and the rotation and revolution of the workpiece 100 are stopped. The vacuum chamber 12 is then opened to the outside, and the workpiece 100 is removed from the vacuum chamber 12. This completes the series of processes, including the film formation process for forming the aluminum nitride film.

[0081] Although the gas flow controller 64 has not been specifically mentioned in the description of this series of processes, particularly in the description of the film formation process, as described above, the gas flow controller 64 controls the mass flow controller 60b for introducing the reactive gas so that the pressure P inside the vacuum chamber 12 is constant. More specifically, it controls the flow rate Qr of the reactive gas introduced into the vacuum chamber 12 via the mass flow controller 60b. Meanwhile, the flow rate Qd of the inert gas is kept constant. Furthermore, by keeping the angle θ (of the blade member) of the conductance valve 22 constant, the effective exhaust speed at the exhaust port 14 of the vacuum chamber 12 is kept constant. By performing the film formation process in this manner, reactive films, including insulating coatings, can be formed with good reproducibility, and particularly, good reproducibility can be obtained for the visible light transmittance (transparency) and film thickness of the reactive film.

[0082] To explain this in more detail in comparison with the conventional technology disclosed in the aforementioned Patent Document 1, the conventional technology also includes a conductance valve similar to that in the present embodiment (although not explicitly stated in Patent Document 1). Meanwhile, in the conventional technology, the flow rate Qd of the inert gas is kept constant, and the flow rate Qr of the reactive gas is also kept constant. Under these conditions, the angle θ of the conductance valve is controlled so that the pressure P in the vacuum chamber is kept constant, i.e., the effective pumping speed at the exhaust port of the vacuum chamber is controlled. That is, the angle θ of the conductance valve is automatically controlled (feedback controlled) using the pressure P in the vacuum chamber 12 as a parameter. In other words, the film formation process is performed in a manner different from that of the present embodiment, in which the flow rate Qr of the reactive gas is automatically controlled using the pressure P in the vacuum chamber 12 as a parameter.

[0083] However, the conventional techniques have the disadvantage that the reaction film is not reproducible, particularly in terms of the visible light transmittance and film thickness of the reaction film, which is presumably due to the fact that the sputtering rate of the sputtered surface of the target changes with each film formation process, i.e., with each batch, and as the batch is repeated.

[0084] The visible light transmittance of the reaction film is affected by the composition of the reaction film. As mentioned above, magnetron plasma is generated in the vacuum chamber so as to adhere to the sputtering surface of the target. In addition, extremely high-density plasma is generated by arc discharge. Therefore, the space to which the sputtering surface is exposed is chemically highly active. Therefore, when a film formation process is performed to form a nitride film, such as an aluminum nitride film, nitrogen penetrates near the boundary between the eroded and non-eroded regions of the sputtering surface of the target, resulting in nitridation (or a phenomenon similar to nitridation) near the boundary. Furthermore, since the degree of nitridation varies from batch to batch, the sputtering rate changes from batch to batch, even over a relatively short period (short span). This changes the composition ratio of the nitride film, and ultimately leads to a loss of reproducibility in the visible light transmittance of the nitride film. A similar phenomenon also occurs when a film formation process is performed to form a reaction film other than a nitride film, such as a carbide film or an oxide film.

[0085] Furthermore, when the sputtering rate changes, the reaction film formation rate (film formation rate) changes, resulting in a change in the thickness of the reaction film. In particular, as batches are repeated (over a long period of time), the sputtering rate decreases, and accordingly, the reaction film formation rate decreases, resulting in a decrease in the thickness of the reaction film. For example, if the initial (new) target has a thickness of 8 mm and the target is used until the depth of the erosion region reaches 7 mm, the surface area of ​​the erosion region of the target at the end of use will be approximately 1.1 times larger than that of the target at the beginning of use. Therefore, when the sputtering power is constant, the power density of the sputtering power acting on the target at the end of use will be approximately 10% lower than that of the target at the beginning of use. It is therefore presumed that as batches are repeated, the sputtering rate decreases, and accordingly, the reaction film formation rate decreases, resulting in a decrease in the thickness of the reaction film.

[0086] To resolve this problem, in this embodiment, the flow rate Qd of the inert gas is kept constant as described above, and the angle θ of the conductance valve 22 is kept constant. Under these conditions, the flow rate Qr of the reactive gas is automatically controlled so that the pressure P in the vacuum chamber 12 is kept constant. The sputtering power Es, the arc discharge power Ed, and the substrate bias voltage Vb (average value) are also kept constant. In particular, the arc discharge power Ed is kept constant by automatically controlling the cathode power Ec so that the arc discharge current Id, which is the current component of the arc discharge power Ed, is kept constant while the arc discharge voltage Vd, which is its voltage component, is kept constant. This stabilizes the sputtering rate of the sputtering surface of the target 242, thereby improving the reproducibility of the reaction film, and in particular the reproducibility of the visible light transmittance and film thickness of the reaction film.

[0087] To verify this, an experiment was conducted in this example to confirm how the pressure P in the vacuum chamber 12 and the flow rate Qr of the nitrogen gas as a reactive gas change during the film formation process to form an aluminum nitride film. As a result, the following was found.

[0088] Although not shown in the figure, observation of the pressure P within the vacuum chamber 12 revealed that the pressure P within the vacuum chamber 12 fluctuates slightly (subtly) while occasionally rising momentarily, that is, transitioning in this manner. Furthermore, observation of the flow rate Qr of nitrogen gas revealed that the flow rate Qr of nitrogen gas fluctuates slightly in synchronization with the transition of the pressure P within the vacuum chamber 12, and occasionally decreases momentarily when the pressure P within the vacuum chamber 12 momentarily rises. The period during which the pressure P within the vacuum chamber 12 momentarily rises, in other words, the period during which the flow rate Qr of nitrogen gas momentarily decreases, is not constant but varies from several minutes to several tens of minutes. Furthermore, the period during which the pressure P within the vacuum chamber 12 momentarily rises, in other words, the period during which the flow rate Qr of nitrogen gas momentarily decreases, lasts for several seconds, specifically 2 to 3 seconds.

[0089] From such transitions of the pressure P inside the vacuum chamber 12 and the flow rate Qr of the nitrogen gas, it is presumed that the following phenomenon occurs in the film forming process for forming the aluminum nitride film.

[0090] That is, in the film formation process for forming a nitride film including an aluminum nitride film, it is believed that the boundary between the erosion region 242a and the non-erosion region of the sputtering surface of the target 242 is nitrided as described above. This nitriding reduces the amount of aluminum particles sputtered from the sputtering surface of the target 242, and therefore reduces the amount of nitrogen gas particles that react with the aluminum particles (sputtered particles). In other words, the amount of nitrogen gas particles consumed by reacting with the aluminum particles decreases. As a result, it is believed that the pressure P in the vacuum chamber 12 increases.

[0091] In this embodiment, the flow rate Qr of nitrogen gas is automatically controlled so that the pressure P in the vacuum chamber 12 remains constant, as described above. Specifically, the flow rate Qr of nitrogen gas is automatically controlled to reduce the increased pressure in the vacuum chamber 12, i.e., the flow rate Qr of nitrogen gas is reduced. This increases the ratio of argon gas particles to nitrogen gas particles in the vacuum chamber 12, thereby increasing the frequency (number of collisions) of argon gas particles, particularly argon ions, with the sputtered surface of the target 242. As a result, the nitride layer formed on the sputtered surface of the target 242 by nitriding is scraped away by the argon ions, increasing the amount of aluminum particles sputtered from the sputtered surface of the target 242. This, in turn, increases the amount of nitrogen gas particles consumed by reacting with the increased amount of aluminum particles, thereby reducing the pressure P in the vacuum chamber 12. In response to this, in order to compensate for the decrease in pressure P within the vacuum chamber 12, in other words, to replenish the nitrogen gas particles required to react with the increased aluminum particles, the flow rate Qr of the nitrogen gas is increased, and the original state is restored.

[0092] As this phenomenon is repeated, according to this embodiment, as described above, the pressure P inside the vacuum chamber 12 occasionally momentarily rises and the flow rate Qr of the nitrogen gas momentarily decreases, and the nitride layer formed on the sputtering surface of the target 242 is appropriately scraped away, so to speak, refreshing the sputtering surface. This stabilizes the sputtering rate on the sputtering surface of the target 242, thereby improving the reproducibility of the aluminum nitride film, and in particular, it is presumed that the reproducibility of the visible light transmittance and film thickness of the aluminum nitride film is improved.

[0093] Although detailed explanation including illustrations will be omitted, in this example, an aluminum nitride film was actually formed and experiments were conducted to determine whether reproducibility could be obtained, particularly whether reproducibility of visible light transmittance and film thickness could be obtained, and it was confirmed that good reproducibility could be obtained. However, this naturally requires that the film formation process be carried out stably, and in particular, anode filaments 70 and 70 play an important role in stably carrying out the film formation process for forming an insulating coating such as an aluminum nitride film.

[0094] That is, as described above, the anode filaments 70 function as anodes for two types of discharge, namely, glow discharge and arc discharge. By providing such anode filaments 70, it becomes possible to stably perform a film formation process for forming an insulating coating such as an aluminum nitride film.

[0095] Specifically, in this embodiment, the ground shield 26 originally functions as an anode for two types of discharge: glow discharge and arc discharge. However, when a film-forming process is performed to form an insulating coating such as an aluminum nitride film, the insulating coating (strictly speaking, the insulating material that constitutes the insulating coating) adheres to the surface of the ground shield 26, particularly to the flat portion 264a of the ground shield 26. If this phenomenon continues, the surface of the ground shield 26, including the flat portion 264a, which strictly speaking can function as an anode, becomes covered with the insulating coating, and the ground shield 26 can no longer function as an anode.

[0096] Meanwhile, in this embodiment, anode filaments 70 and 70 are provided near the earth shield 26, more specifically near the flat portion 264a. Each anode filament 70 is set to a predetermined potential equal to or higher than the ground potential (0 V). Therefore, electrons in the plasma 300 flow not only into the earth shield 26 but also into each anode filament 70. That is, each anode filament 70 also functions as an anode for two types of discharge: glow discharge and arc discharge.

[0097] Furthermore, each anode filament 70 is a thin, linear member made of tungsten and approximately 1 mm in diameter. As electrons in the plasma 300 flow into it, it is heated by Joule heat, particularly to temperatures above 1500°C, causing it to glow red. When the anode filament 70 glows red, even if an insulating coating (strictly speaking, sputtered particles before reacting with reactive gas particles) adheres to the surface of the anode filament 70, the adhered insulating coating re-evaporates. Therefore, the surface of the anode filament 70 remains conductive, thereby maintaining the anode function of the anode filament 70 and preventing the loss of the anode. Furthermore, the generation of plasmoids is also prevented. As a result, the discharge (plasma 300) is maintained, enabling stable film formation processes for forming insulating coatings such as aluminum nitride films.

[0098] Note that when the sputtering power Es (i.e., sputtering output) and the arc discharge power Ed (i.e., arc output) are relatively high, even if the anode filament 70 is at ground potential, i.e., even if the anode filament voltage Vaf is 0 V, the anode filament 70 will glow red sufficiently, and strictly speaking, even if an insulating coating adheres to its surface, it will be heated enough to evaporate the coating and maintain its function as an anode. On the other hand, when the sputtering power Es and the arc discharge power Ed are relatively low, if the anode filament 70 is at ground potential, i.e., if the anode filament voltage Vaf is 0 V, the anode filament 70 may not glow red, and may not be able to maintain its function as an anode. In such a case, by setting the anode filament voltage Vaf to an appropriate value greater than 0 V, the inflow of electrons into the anode filament 70 is promoted, causing the anode filament 70 to glow red, and thereby maintaining its function as an anode. However, the anode filament voltage Vaf is set to 30V or less for reasons that will be described later, that is, within the range of 0V to 30V as appropriate.

[0099] FIG. 7 shows a photograph of a portion including the magnetron sputtering cathode 24 during a film formation process to form an aluminum nitride film. As can be seen from FIG. 7, each anode filament 70 is red-hot, which suggests that the anode filament 70 is heated to 1500°C or higher. The cathode filament 30 is more white than red, which suggests that the cathode filament 30 is heated to 2000°C or higher. The area in front of the target 242 is slightly purplish-whitish, which represents the plasma 300. After the film formation process under the conditions shown in FIG. 7 was performed, the surfaces of each anode filament 70 were inspected. It was confirmed that no aluminum nitride film had adhered to the surface of the anode filament 70 and that electrical conductivity was maintained.

[0100] The film formation conditions when the photographed image shown in FIG. 7 was obtained were as follows:

[0101] Argon gas flow rate Qd 150mL / min Nitrogen gas flow rate Qr 140~130mL / min (automatic control) Vacuum chamber pressure P 0.220Pa Conductance valve angle θ 40 degrees Sputtering power Qs 15kW (395V x 47.4A x 0.8) Arc discharge power Ed 250W (50V x 5A) Anode filament voltage Vaf 0V (ground potential) Anode filament current Iaf 13.7A

[0102] As mentioned above, in this embodiment, the nitrogen gas flow rate Qr is automatically controlled so that the pressure P inside the vacuum chamber 12 is constant. Therefore, the nitrogen gas flow rate Qr fluctuates within a range of 140 mL / min to 130 mL / min. The details of the sputtering power Qs of 15 kW are: a sputtering voltage Vs (average value) of −395 V; a sputtering current Is, which is the current component of the sputtering power Qs, of 47.4 A; and a duty ratio of 20%. The details of the arc discharge power Ed of 250 W are: an arc discharge voltage Vd of 50 V; and an arc discharge current Id of 5 A. Furthermore, the anode filament current Iaf is the sum of the currents (electron currents) flowing through the two anode filaments 70, 70 due to the flow of electrons from the plasma 300 into the two anode filaments 70.

[0103] For example, when the sputtering power Qs is relatively low (5 kW), if the anode filament voltage Vaf is 0 V, i.e., if the anode filament 70 is at ground potential, the anode filament 70 will not glow red. Furthermore, in this state, the anode filament current Iaf is relatively low (8.7 A). In this case, setting the anode filament voltage Vaf to 15 V increases the anode filament current Iaf to 13.1 A, thereby confirming that, similar to when the sputtering power Qs is 15 kW, each anode filament 70 glows red and the surface conductivity of each anode filament 70 is maintained. This means that even under film formation conditions in which the formation rate of an aluminum nitride film is reduced to one-third, by appropriately setting the anode filament voltage Vaf, the anode filaments 70 can maintain their anode function, thereby enabling stable film formation processes for forming insulating coatings such as aluminum nitride films.

[0104] In addition, an experiment was conducted to confirm how the anode filament current Iaf changes over time during a film formation process to form an aluminum nitride film, in other words, how it changes depending on the state of the earth shield 26. The results are shown in FIG. 8. In FIG. 8, the thick solid line marked with a ● symbol indicates the change in the anode filament current Iaf when the anode filament voltage Vaf is 0 V, that is, when each anode filament 70 is at ground potential. The thick solid line marked with a ■ symbol indicates the change in the anode filament current Iaf when the anode filament voltage Vaf is 15 V.

[0105] The film formation conditions in this experiment were as follows. In particular, the flow rate Qr of the nitrogen gas was not automatically controlled but was kept constant. This experiment was conducted after the earth shield 26 had been thoroughly cleaned (blasted) so that the earth shield 26 could function adequately as an anode.

[0106] Argon gas flow rate Qd 150mL / min Nitrogen gas flow rate Qr 100mL / min Vacuum chamber pressure P 0.220Pa Conductance valve angle θ 40 degrees Sputtering power Qs 15kW (395V x 47.4A x 0.8) Arc discharge power Ed 250W (50V x 5A)

[0107] According to this experiment, as shown in Figure 8, the anode filament current Iaf increases over time whether the anode filament voltage Vaf is 0 V or 15 V. The anode filament current Iaf then saturates after about 60 minutes have passed. From this change in the anode filament current Iaf, the following can be inferred.

[0108] That is, at the beginning of the film formation process, both the ground shield 26 and each anode filament 70 function as an anode, and therefore the amount of electrons flowing into each anode filament 70 is small due to the amount of electrons in the plasma 300 flowing into the ground shield 26, i.e., the anode filament current Iaf is small. Then, as time passes, that is, as the film formation process progresses, an aluminum nitride film adheres to the surface of the ground shield 26, including the flat portion 264a of the ground shield 26, and the amount of electrons flowing from the plasma 300 into the ground shield 26 decreases. Meanwhile, to maintain itself (discharge), the plasma 300 searches for an anode to replace the ground shield 26, and as a result, the amount of electrons flowing from the plasma 300 into each anode filament 70 increases, which increases the anode filament current Iaf. After about 60 minutes have passed, the earth shield 26 is hardly able to function as an anode, and each anode filament 70 functions mainly as an anode, and as a result, it is estimated that the anode filament current Iaf becomes saturated.

[0109] Note that when the anode filament voltage Vaf is 0 V, the anode filament current Iaf saturates at approximately 13.5 A. This value of approximately 13.5 A is considered to be the minimum value of the anode filament current Iaf required to stably maintain the plasma 300. Furthermore, in the experimental results shown in FIG. 8, the anode filament current Iaf tends to decrease for approximately 5 minutes after the start of the film formation process, whether the anode filament voltage Vaf is 0 V or 15 V, but the reason for this is unclear. In any case, this experiment revealed that the anode filament current Iaf increases over time, whether the anode filament voltage Vaf is 0 V or 15 V, and then saturates after approximately 60 minutes have elapsed.

[0110] Furthermore, an experiment was conducted to confirm the relationship between the anode filament voltage Vaf and the anode filament current Iaf during a film formation process to form an aluminum nitride film. The results are shown in Figure 9. In Figure 8, the thick solid line marked with a ● symbol indicates the relationship between the anode filament voltage Vaf and the anode filament current Iaf when the sputtering power Qs is 0 kW, that is, when no glow discharge is induced and only an arc discharge is induced. The thick solid line marked with a ■ symbol, the thick solid line marked with a ○ symbol, and the thick solid line marked with a □ symbol indicate the relationship between the anode filament voltage Vaf and the anode filament current Iaf when the sputtering power Qs is 5 kW, 10 kW, and 15 kW, respectively.

[0111] The film formation conditions in this experiment were as follows. In particular, the flow rate Qr of the nitrogen gas was not automatically controlled but was kept constant. The experiment was conducted after the surface of the ground shield 26 was sufficiently covered with the aluminum nitride film, that is, after the ground shield 26 was in a state where it could hardly function as an anode.

[0112] Argon gas flow rate Qd 150mL / min Nitrogen gas flow rate Qr 100mL / min Vacuum chamber pressure P 0.220Pa Conductance valve angle θ 40 degrees Arc discharge power Ed 250W (50V x 5A)

[0113] According to this experiment, as shown in Figure 9, when the sputtering power Qs is 0 kW, that is, when only arc discharge is induced, the relationship between the anode filament voltage Vaf and the anode filament current Iaf shows that the anode filament current Iaf is approximately 0.4 A when the anode filament voltage Vaf is 0 V. This means that only 0.4 A of the 5 A sputtering current Is flows through the anode filaments 70 and 70, while the remaining 4.6 A flows to appropriate locations on the wall of the vacuum chamber 12, thereby maintaining the arc discharge. As the anode filament voltage Vaf increases, the anode filament current Ia also increases, and the anode filament current Iaf tends to saturate when the anode filament voltage Vaf reaches approximately 15 V or higher.

[0114] In contrast, when the sputtering power Qs is 5 kW, 10 kW, or 15 kW, even if the anode filament voltage Vaf increases, the anode filament current Iaf does not change significantly but tends to increase monotonically, reaching a generally saturated state. When the anode filament voltage Vaf is 0 V, the anode filament current Iaf is approximately 10 A. This, compared with the anode filament current Iaf of approximately 0.4 A when the sputtering power Qs is 0 kW, suggests that most of the electrons flowing into the anode filaments 70 and 70 are electrons from glow discharge. Incidentally, a comparison of the anode filament current Iaf with the sputtering current Is for inducing glow discharge revealed that 30% to 40% of the sputtering current Is flows through the anode filaments 70 and 70 as an electron current.

[0115] Furthermore, according to the experimental results shown in FIG. 9 , when the sputtering power Qs is 5 kW, 10 kW, or 15 kW, the anode filament current Iaf tends to increase slightly as the anode filament voltage Vaf increases. Therefore, the higher the anode filament voltage Vaf, the greater the anode filament current Iaf, ensuring that each anode filament 70 glows red. However, if the anode filament voltage Vaf is excessively high, specifically 40 V or higher, the space potential of the plasma 300 becomes excessively high, causing arc marks (discharge marks) to appear in the vacuum chamber 12, which is undesirable. To avoid this drawback, the anode filament voltage Vaf is preferably less than 40 V, and is set to 30 V or less with an appropriate margin, i.e., within the range of 0 V to 30 V. Furthermore, within this range, particularly when the anode filament voltage Vaf is 30 V, the anode filaments 70 and 70 glow red reliably. For these reasons, the anode filament voltage Vaf is set to the minimum value necessary to reliably make the anode filaments 70 glow red.

[0116] Furthermore, an experiment was conducted to confirm how the substrate current Ib, which is a current component of the substrate bias power Eb, i.e., the substrate current Ib, which is the current flowing through the workpiece 100, changes over time during the film formation process for forming an aluminum nitride film, in other words, depending on the state of the earth shield 26. Additionally, for comparison with this embodiment, a pseudo-conventional technique was created by removing the anode filaments 70 and 70, and an experiment was also conducted to confirm how the substrate current Ib changes for this pseudo-conventional technique. The results are shown in detail in FIG. 10, which shows an example of log data recording the substrate current Ib over time.

[0117] FIG. 10(a) shows the experimental results for the pseudo conventional technique, and FIG. 10(b) shows the experimental results for this embodiment. In each of FIGS. 10(a) and 10(b), log data of the substrate bias voltage Vb (average value) is also shown for reference. The horizontal axis in each of FIGS. 10(a) and 10(b) represents time, with one division on the horizontal axis corresponding to approximately 80 minutes. The time t0 on the horizontal axis indicates the time when the film formation process started.

[0118] The film formation conditions in this experiment were as follows: In particular, in the experiment for this embodiment, the anode filament voltage Vaf was set to 0 V, that is, each anode filament 70 was set to the ground potential.

[0119] Argon gas flow rate Qd 150mL / min Nitrogen gas flow rate Qr 140~130mL / min (automatic control) Vacuum chamber pressure P 0.220Pa Conductance valve angle θ 40 degrees Sputtering power Qs 15kW (395V x 47.4A x 0.8) Arc discharge power Ed 250W (50V x 5A) Substrate bias voltage Vb (average value) -150V Film formation time: 360 minutes

[0120] First, focusing on the experimental results for the conventional technology shown in FIG. 10( a), in the experiment for the conventional technology, the substrate bias voltage Vb was set to 0 V, i.e., the substrate bias power Eb was not supplied, for 10 minutes from time t0 when the film formation process was started. Then, at 10 minutes after time t0, the substrate bias voltage Vb was set to −50 V, and this state was maintained for 5 minutes. Then, at 15 minutes after time t0, the substrate bias voltage Vb was set to −100 V, and this state was maintained for 5 minutes. Then, at 20 minutes after time t0, the substrate bias voltage Vb was set to its initial value of −150 V, and this state was maintained until the film formation process was completed. In this way, the absolute value of the substrate bias voltage Vb was gradually increased in the initial period immediately after the start of the film formation process, thereby improving the adhesion of the aluminum nitride film to the surface of the workpiece 100. That is, the smaller the absolute value of the substrate bias voltage Vb, the softer the aluminum nitride film that is formed. However, in the initial period immediately after the start of the film formation process, by gradually increasing the absolute value of the substrate bias voltage Vb, a gradually harder aluminum nitride film is formed, and as a result, the adhesion of the entire aluminum nitride film to the surface of the workpiece 100 is improved.

[0121] The period during which the substrate bias voltage Vb is at its initial value of −150 V is called the topcoat processing period. During this topcoat processing period, i.e., from 20 minutes after the start of the film formation process t0, the substrate current Ib gradually increases and approximately saturates after the first 50 minutes of the topcoat processing period. This substrate current Ib fluctuates (increases or decreases) within a certain range, due to the rotation and revolution of the workpiece 100. As described above, the film formation process is performed on the workpiece 100 while it is exposed to the plasma 300 during its rotation and revolution. Therefore, the number (surface area) of workpieces 100 subjected to the film formation process changes over time. Therefore, the substrate current Ib flowing through the workpiece 100 changes over time, i.e., fluctuates within a certain range. The more unstable the plasma 300, the larger the fluctuation range of this substrate current Ib, and in experiments using conventional technology, it was confirmed to be a large value of approximately 2 A. Furthermore, when the inside of vacuum chamber 12 was observed in this state, it was confirmed that plasma 300 was unstable, and plasmoids were generated in places, with the generation and disappearance of these plasmoids repeating.

[0122] In contrast, the experimental results for this embodiment shown in FIG. 10(b) reveal that, like the experiment for the prior art, the absolute value of the substrate bias voltage Vb is gradually increased in the initial period immediately after the start of the film formation process. Meanwhile, the experimental results for this embodiment, unlike the experimental results for the prior art, reveal that the substrate current Ib is stable during the topcoat treatment, with a fluctuation range of approximately 0.8 A. That is, this embodiment confirms that the fluctuation range of the substrate current Ib is suppressed to approximately 40% compared to the prior art. Furthermore, when observing the inside of the vacuum chamber 12 in this state, no plasmoid was observed, confirming that the plasma 300 was stable.

[0123] Furthermore, in this example, an aluminum nitride film was actually formed and an experiment was conducted to confirm its internal stress and Knoop hardness. Additionally, an aluminum nitride film was actually formed using the aforementioned pseudo-conventional technology and its internal stress and Knoop hardness were confirmed. The results are shown in Figure 11.

[0124] 11(a) shows the experimental results for internal stress, and FIG. 11(b) shows the experimental results for Knoop hardness. In both figures, the thick solid line marked with a ■ symbol indicates the experimental results for this embodiment, and the thick solid line marked with a ● symbol indicates the experimental results for the prior art. Although not shown, in this experiment, a roughly cylindrical substrate stand with a diameter of 140 mm and a length of 600 mm was attached to holder 40, and experimental samples were attached at five positions along the length of the substrate stand: 60 mm, 180 mm, 300 mm, 420 mm, and 540 mm from holder 40. The internal stress and Knoop hardness of the aluminum nitride films formed on these samples were measured. The sample used for internal stress measurement was silicon (Si) with a side length of 20 mm and a thickness of 630 μm, and the sample used for Knoop hardness measurement was mirror-finished high-speed steel (SKH4) with a longitudinal dimension of 25 mm, a lateral dimension of 15 mm, and a thickness of 5 mm.

[0125] Focusing on the experimental results for internal stress shown in Figure 11(a), the difference between the maximum and minimum values ​​of the internal stress of the aluminum nitride film formed by the conventional technology is approximately 4.24 GPa, i.e., there is a large variation of approximately 4.24 GPa. An aluminum nitride film with such a large variation in internal stress is not practical. In contrast, the difference between the maximum and minimum values ​​of the internal stress of the aluminum nitride film formed by this example is approximately 0.015 GPa, i.e., the variation is suppressed to an extremely small value of approximately 0.015 GPa. In other words, with the aluminum nitride film formed by this example, the variation in internal stress is suppressed to 0.4% or less compared to the aluminum nitride film formed by the conventional technology. An aluminum nitride film with such an extremely small variation in internal stress is fully suitable for practical use.

[0126] Furthermore, the experimental results for Knoop hardness shown in FIG. 11(b) reveal that the difference between the maximum and minimum Knoop hardness values ​​of the aluminum nitride film formed by the conventional technology is approximately 670 HK, i.e., there is a large variation of approximately 670 HK. An aluminum nitride film with such a large variation in Knoop hardness is not practical. In contrast, the difference between the maximum and minimum Knoop hardness values ​​of the aluminum nitride film formed by this embodiment is approximately 70 HK, i.e., the variation is suppressed to an extremely small value of approximately 70 HK. In other words, the aluminum nitride film formed by this embodiment suppresses the variation in Knoop hardness to 10% or less compared to aluminum nitride films formed by the conventional technology. An aluminum nitride film with such a small variation in Knoop hardness is fully suitable for practical use. Although the Knoop hardness of the aluminum nitride film formed by this embodiment is generally lower than that of the aluminum nitride film formed by conventional technology, the Knoop hardness of the film formed by this embodiment is approximately 2000 HK, which is sufficient for practical use.

[0127] That is, according to this example, it is possible to form a homogeneous aluminum nitride film with small variations in both internal stress and Knoop hardness. Although detailed explanation including drawings will be omitted, it was confirmed that both in this example and in the pseudo-conventional technology, variations in the thickness of the aluminum nitride film were sufficiently suppressed, that is, aluminum nitride films with uniform thickness were formed.

[0128] As described above, according to this embodiment, the film formation process for forming an insulating film such as an aluminum nitride film can be stably performed, and a uniform insulating film can be formed. This is extremely useful, particularly in applications where a film is to be formed on a workpiece 100 having a large surface area.

[0129] Furthermore, according to this embodiment, the sputtering rate is stabilized, which improves the reproducibility of reactive films including insulating films such as aluminum nitride films, and in particular improves the reproducibility of visible light transmittance and film thickness, which is extremely useful in applications where reproducibility of visible light transmittance and film thickness is required.

[0130] It should be noted that this embodiment is merely a specific example of the present invention and does not limit the technical scope of the present invention. The present invention can also be applied to aspects other than this embodiment.

[0131] 12, a plurality of magnetron sputtering cathodes 24, 24, ... may be provided, and strictly speaking, a plurality of units 400, i.e., four units 400 each including the magnetron sputtering cathode 24, may be provided. Specifically, each unit 400 includes the magnetron sputtering cathode 24, an earth shield 26, a cathode filament 30, and two anode filaments 70 and 70. Although not shown in FIG. 12, each unit 400 also includes a sputtering power supply 28, a heating power supply 32, an arc discharge power supply 34, a current detector 36, a heating controller 38, a reactor 72, and an anode filament power supply 74. In other words, each unit 400 is, so to speak, a source of plasma 300, and a plurality of units 400, i.e., four units 400, as sources of plasma 300, may be provided. These units 400, 400, ... are provided at equal intervals along the circumferential direction of a circle centered on the central axis Xa of the vacuum chamber 12, that is, at 90-degree intervals in this example. In addition, each unit 400, 400, ... is provided at the same distance from the central axis Xa of the vacuum chamber 12.

[0132] 12, the deposition rate of the reactive film is improved (faster). Also, in the configuration shown in FIG. 12, the flow rate Qr of the nitrogen gas is automatically controlled so that the pressure P inside the vacuum chamber 12 is constant, thereby improving the reproducibility of the reactive film. Furthermore, the elements responsible for this automatic control, namely, the pressure gauge 62, the gas flow controller 64, and the mass flow controller 60b for introducing the reactive gas, do not need to be provided in multiples; only one common element is required for each of the units 400, 400, ...

[0133] The number of units 400 is not limited to four. In any case, it is essential that the units 400, 400, ... are provided at equal intervals along the circumferential direction of a circle centered on the central axis Xa of the vacuum chamber 12, and are provided at equal distances from the central axis Xa of the vacuum chamber 12.

[0134] 10(a) and 10(b) are actually obtained from a configuration in which two units 400 and 400 are provided. Therefore, the total sputtering power Qs when the experimental results shown in Fig. 10(a) and 10(b) were obtained was 30 kW (= 15 kW × 2) for the two units 400 and 400, and the total arc discharge power Ed was also 500 W (= 250 W × 2) for the two units 400 and 400.

[0135] In this embodiment, the case where an aluminum nitride film is formed as an insulating film has been described, but the present invention can also be applied to the case where various insulating films other than the aluminum nitride film, such as nitride films, carbide films, and oxide films, are formed. The various insulating films referred to here include reactive films such as silicon nitride (SiN) film, silicon carbide (SiC) film, silicon oxide (SiO2) film, aluminum oxide (Al2O3) film, yttrium oxide (YO3) film, zirconium oxide (ZO4) film, and the like. r In this case, a target 242 made of a material according to the type of reaction film is used.

[0136] Additionally, in this embodiment, the reactor 72 is provided, but if the effect of noise caused by the sputtering power Es is small, the reactor 72 may not be provided. Also, if the anode filaments 70 and 70 are sufficient at ground potential, the anode filament power supply device 74 may not be provided.

[0137] Furthermore, in this embodiment, a pulse power supply is used as the bias power supply 50, but this is not limiting. For example, if the workpiece 100 is made of an insulating material, a high-frequency power supply may be used as the bias power supply 50 depending on the size, shape, physical properties, and other characteristics of the workpiece 100.

[0138] The present invention is not limited to application to the magnetron sputtering apparatus 10, but can also be applied to a film formation method using magnetron sputtering. [Explanation of symbols]

[0139] 10...Magnetron sputtering equipment 12 … Vacuum chamber 18... Vacuum pump 20... Opening and closing valve 22... Conductance valve 24...Magnetron cathode 26... Earth Shield 28 ... Sputter power supply 30... cathode filament 32 ... Filament heating power supply 34 ... Arc discharge power supply 36... Current detector 38... Heating controller 50... Bias power supply 56... Gas inlet pipe 58,60 … branch pipe 58a, 60a ... Opening and closing valve 58b, 60b ... Mass flow controller 62 … Vacuum gauge 64...Gas flow controller 70...Anode filament 72... Reactor 74 ... Anode filament power supply 100...Processed object 242 … Target 300... Plasma 400 … units

Claims

1. A film forming apparatus for forming an insulating film on a workpiece by magnetron sputtering, a vacuum chamber that is at ground potential and that accommodates the workpiece; a magnetron sputtering cathode having a target that is a material for the insulating coating, the magnetron sputtering cathode being provided inside the vacuum chamber so that a substantially rectangular planar sputtering surface of the target faces the workpiece; an earth shield that is set to a ground potential and is provided so as to surround the outer periphery of the magnetron sputtering cathode while exposing the sputtering surface in order to limit the sputtering area of ​​the magnetron sputtering cathode to the sputtering surface; an exhaust means having a vacuum pump that exhausts the inside of the vacuum chamber through an exhaust port of the vacuum chamber; an inert gas introducing means for introducing an inert gas into the vacuum chamber; a sputtering power supply means for supplying sputtering power to the earth shield and the magnetron sputtering cathode, with the earth shield serving as an anode and the magnetron sputtering cathode serving as a cathode, for discharging particles of the inert gas; a reactive gas introducing means for introducing a reactive gas that will be a material for the insulating coating into the vacuum chamber; a bias power supply means for supplying bias power having a constant predetermined component to the vacuum chamber and the workpiece, with the vacuum chamber as an anode and the workpiece as a cathode, for accelerating the inert gas particles, the reactive gas particles, and the sputtered particles sputtered from the sputtering surface toward the workpiece; a linear cathode filament extending along the longitudinal direction of the sputtering surface between the sputtering surface and the workpiece; a heating power supply means for supplying heating power to the cathode filament to heat the cathode filament and cause thermions to be emitted from the cathode filament; an arc discharge power supply means for supplying arc discharge power to the earth shield and the cathode filament, with the earth shield serving as an anode and the cathode filament serving as a cathode, for accelerating the thermoelectrons toward the earth shield; a heating power control means for controlling the heating power so that a current component of the arc discharge power is constant while the voltage component of the arc discharge power is constant; and a linear anode filament that is disposed in parallel with the cathode filament near the earth shield, that is at ground potential or a positive potential relative to the ground potential, and that glows red in response to an inflow of electrons in plasma generated by discharge between the inert gas particles, the reactive gas particles, and the sputtered particles.

2. The film forming apparatus according to claim 1 , wherein the value of the positive potential is greater than 0 V and less than or equal to 30 V.

3. The film forming apparatus according to claim 1 , wherein the cathode filament and the anode filament are made of the same material.

4. the cathode filament and the anode filament are each provided to extend in a vertical direction, 2. The film forming apparatus according to claim 1, wherein an upper end of the anode filament is fixed to a support member as a fixed end, and a lower end of the anode filament is left hanging down as a free end.

5. two anode filaments; the cathode filament is provided at a position corresponding to the center of the sputtering surface in the short-side direction of the sputtering surface, 2. The film forming apparatus according to claim 1, wherein the two anode filaments are provided symmetrically with respect to an imaginary plane that includes an axis of the cathode filament and is perpendicular to the surface to be sputtered.

6. the earth shield has a flat surface that is substantially flush with the sputtered surface, 6. The film forming apparatus of claim 5, wherein each of the two anode filaments is provided at a position corresponding to the edge of the sputtered surface closest to itself in the short direction of the sputtered surface or at a position spaced 15 mm or less outward from said position on the sputtered surface, and is provided at a position spaced 5 mm or more and 30 mm or less from said flat surface in a direction perpendicular to the flat surface of the earth shield in the direction in which the sputtered surface is facing.

7. the exhaust means further includes a conductance valve that controls an effective exhaust speed at the exhaust port; 2. The film forming apparatus according to claim 1, further comprising a reactive gas flow rate control means for controlling the flow rate of the reactive gas introduced into the vacuum chamber so that the pressure inside the vacuum chamber is constant while the flow rate of the inert gas introduced into the vacuum chamber is kept constant, the sputtering power is kept constant, and the effective exhaust speed is kept constant by the conductance valve.

8. 2. The film forming apparatus according to claim 1, comprising a plurality of units each having the magnetron sputtering cathode, the earth shield, the sputtering power supply means, the cathode filament, the heating power supply means, the arc discharge power supply means, the heating power control means, and the anode filament.

9. A film formation method for forming an insulating film on a workpiece by magnetron sputtering, comprising: a workpiece placement step of placing the workpiece inside a vacuum chamber that is set to ground potential and that is provided with a magnetron sputtering cathode having a target that will be the material for the insulating coating, so that the workpiece faces a sputtering surface of the target that has a substantially rectangular planar shape; an exhaust step of evacuating the inside of the vacuum chamber through an exhaust port of the vacuum chamber by a vacuum pump; an inert gas introducing step of introducing an inert gas into the vacuum chamber; a sputtering power supply step of supplying sputtering power to the earth shield as an anode and the magnetron sputtering cathode as a cathode, the earth shield being set to a ground potential and provided so as to surround the outer periphery of the magnetron sputtering cathode while exposing the sputtering surface in order to limit the sputtering area of ​​the magnetron sputtering cathode to the sputtering surface, for discharging particles of the inert gas; a reactive gas introduction step of introducing a reactive gas that will be a material for the insulating coating into the vacuum chamber; a bias power supply step of supplying bias power having a constant predetermined component to the vacuum chamber and the workpiece, using the vacuum chamber as an anode and the workpiece as a cathode, for accelerating the inert gas particles, the reactive gas particles, and the sputtered particles sputtered from the sputtering surface toward the workpiece; a heating power supply step of supplying a heating power to a linear cathode filament provided between the sputtering surface and the workpiece so as to extend along the longitudinal direction of the sputtering surface, thereby heating the cathode filament and emitting thermoelectrons from the cathode filament; an arc discharge power supply step of supplying arc discharge power to the earth shield and the cathode filament, with the earth shield serving as an anode and the cathode filament serving as a cathode, for accelerating the thermoelectrons toward the earth shield; a heating power control step of controlling the heating power so that a current component of the arc discharge power is constant while a voltage component of the arc discharge power is constant; and a film forming method including an anode maintenance step of causing electrons in plasma generated by discharge between the inert gas particles, the reactive gas particles, and the sputtered particles to flow into a linear anode filament, the anode filament being disposed in parallel to the cathode filament near the earth shield and at ground potential or a positive potential relative to the ground potential, thereby heating the anode filament to red heat.

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