JP6533913B2 - Plasma surface treatment system - Google Patents

Description

  The present invention relates to a plasma surface treatment apparatus for performing predetermined treatment on the surface of an object using plasma.

  As this kind of plasma surface treatment apparatus, for example, one disclosed in Patent Document 1 is known. According to this prior art, a substantially cylindrical vacuum vessel whose both ends are closed is installed with the both ends up and down, that is, with its own central axis extended in the up and down direction. The vacuum chamber is made of metal having high corrosion resistance and heat resistance, for example, stainless steel, and the wall portion thereof is connected to a ground potential as a reference potential. In addition, an exhaust port is provided at an appropriate position of a wall portion of the vacuum chamber, and a vacuum pump as an exhaust unit outside the vacuum chamber is coupled to the exhaust port.

  Further, a plasma gun as a plasma generation means is provided substantially at the center on the wall portion forming the upper surface of the vacuum chamber. The plasma gun has a generally cylindrical housing that is generally smaller than the vacuum chamber and closed at both ends. This housing is made of, for example, stainless steel, and is concentric with the vacuum chamber, that is, with its central axis aligned with the central axis of the vacuum chamber and electrically insulated from the vacuum chamber. That is, it is coupled to the vacuum chamber in a state of being at an insulating potential (floating potential). Further, a substantially cylindrical aperture whose both ends are opened is provided substantially at the center of the wall portion forming the lower surface of the housing in a state where the central axis of itself is aligned with the central axis of the housing. And the inside of a case and the inside of a vacuum vessel are mutually connected via this aperture.

  A thermal cathode as a thermal electron emitting means and an anode as an anode means are provided in a housing of a plasma gun. Among them, the hot cathode is composed of linear tungsten (W) filaments, and on the central axis of the housing, it faces the aperture, and more specifically, orthogonally to the central axis of the housing. , Is provided. Then, direct current power is supplied as cathode power to the hot cathode from a direct current power supply device located outside the housing. On the other hand, the anode is a flat circular ring made of molybdenum (Mo), and it is described in detail so as to face the hot cathode at a position between the hot cathode and the aperture on the central axis of the housing. Is provided in a state in which the central axis of itself coincides with the central axis of the casing. The anode is connected to the ground potential, and the anode is supplied with DC power of positive potential based on the potential of the hot cathode as anode power from another DC power supply device outside the housing. Be done. Furthermore, a discharge gas supply port for supplying a discharge gas into the housing is provided at an appropriate position of the wall portion of the housing.

  On the other hand, a reflective electrode is provided in the vacuum chamber. The reflective electrode comprises a substantially circular dish-shaped metal container and metal wool contained in the container, but may be, for example, a simple disk-shaped metal body. . The reflective electrode faces the plasma gun at a position near the lower surface of the vacuum chamber on the central axis of the vacuum chamber, and more specifically, in a state in which the central axis of itself is aligned with the central axis of the vacuum chamber. It is provided. The reflective electrode is also electrically insulated as in the case of the plasma gun case. Furthermore, in the vicinity of the upper surface in the vacuum chamber, a disk-like plasma stabilizing electrode as blocking means is provided so as to entirely cover the upper surface in the vacuum chamber and not to interfere with the aperture. There is. The plasma stabilizing electrode is also made of metal and is electrically insulated.

  Then, in the vacuum chamber, a plurality of objects to be processed are disposed along the circumferential direction of a circle centered on the central axis of the vacuum chamber. Each object to be treated is supported by a holder as a support means, and moves in the circumferential direction of the circle, that is, it rotates around the central axis of the vacuum chamber, so to say, it revolves. At the same time, each object to be treated rotates about a vertical axis passing through itself, so to speak, to rotate.

  In addition, in the upper and lower portions outside the vacuum chamber, a pair of electromagnetic coils formed along the respective peripheral edges of the upper surface and the lower surface of the vacuum chamber are provided. The pair of electromagnetic coils receive supply of direct current to form a mirror magnetic field in the vacuum chamber and the plasma gun housing, and more specifically, along the central axis of the vacuum chamber and the central axis of the plasma gun housing Apply a magnetic field in the direction.

  In this prior art, when surface treatment is performed, first, an object to be treated is accommodated in a vacuum chamber, and then the inside of the vacuum chamber and the inside of the plasma gun housing are evacuated by a vacuum pump. Then, while the cathode power is supplied to the hot cathode, the anode power is supplied to the anode. Then, the hot cathode is heated and hot electrons are emitted from the hot cathode. Then, the thermoelectrons are accelerated toward the anode. In this state, when, for example, argon (Ar) gas as a discharge gas is supplied into the housing of the plasma gun, thermions accelerated from the hot cathode toward the anode collide with the argon gas particles. By the impact, argon gas particles are ionized to generate plasma. Furthermore, when a magnetic field is applied by the pair of electromagnetic coils described above, the thermal electrons spirally move to wind around the magnetic field. As a result, the number and probability of the thermal electrons colliding with the argon gas particles are increased, and the density of plasma is improved. Then, the plasma is supplied into the vacuum chamber along the magnetic field and hence through the aperture.

  The plasma supplied into the vacuum chamber flows toward the reflective electrode. However, since the reflective electrode is electrically insulated as described above, electrons in the plasma are reflected by the reflective electrode and folded back toward the plasma gun, but the case of the plasma gun is also Since the electrically isolated potential is set, electrons in the plasma reciprocate between the plasma gun and the reflective electrode, and so-called electric field oscillation occurs. Furthermore, since the above-mentioned magnetic field is applied in the vacuum chamber, the electrons in the plasma are generally beam-shaped so as to be concentrated along the magnetic field, that is, toward the central axis of the vacuum chamber. Be trapped. This further improves the density of the plasma. The plasma generation mechanism having such a configuration, that is, the plasma generation mechanism having a configuration in which an annular anode is disposed between the hot cathode and the reflective electrode and a magnetic field in a direction along these arrangement axes is applied is It is called PIG (Penning Ionization Gauge) discharge mechanism.

  Each object to be treated is disposed so as to surround this beam-like plasma, and the objects to be treated revolve around the plasma while rotating. As a result, the plasma acts evenly on the surface of each object to be treated, and a predetermined treatment using this plasma is uniformly applied over the entire surface of the object to be treated.

  As described above, the anode in the plasma gun housing is connected to the ground potential, and to this anode, direct-current power of positive potential based on the potential of the hot cathode is supplied as anode power. . Therefore, the space potential in the housing, that is, the space potential of the plasma is stabilized with reference to the ground potential.

  In addition, electrons in the plasma supplied from the plasma gun into the vacuum chamber try to flow into the wall of the vacuum chamber at the same potential (ground potential) as the anode, and in particular, the vacuum chamber to which the plasma gun is coupled Try to flow into the top part of the inside. However, since the upper surface portion in the vacuum chamber is covered by the plasma stabilizing electrode which is electrically insulated as described above, even if electrons in the plasma flow into the upper surface portion in the vacuum chamber, Its progress is blocked by the plasma stabilizing electrode. Therefore, the wall of the vacuum chamber including the upper surface portion in the vacuum chamber does not act as an anode (in other words, unintentionally), and the plasma is further stabilized.

JP, 2006-169562, A

  By the way, in the above-mentioned prior art, each object to be treated revolves around the beam-like plasma while rotating, so even if the number of the object to be treated is only one, the object to be treated is accommodated. As a vacuum chamber, one having a corresponding size, specifically, one having an inner diameter that allows the material to be treated to revolve around a beam-like plasma while rotating is required. Therefore, in particular, when trying to cope with a large object to be treated, specifically an object to be treated having a relatively large dimension in the radial direction of its own rotation shaft, a vacuum chamber having a correspondingly large inner diameter is required, and thus the vacuum The entire plasma surface treatment apparatus including the tank is enlarged. Also, of course, the manufacturing cost of the entire apparatus is increased. That is, in the prior art, in particular, there is a problem that it is difficult to cope with a large object to be treated.

  Therefore, an object of the present invention is to provide a plasma surface treatment apparatus that can easily and flexibly cope with a large-sized workpiece.

The present invention has a vacuum chamber, and a plasma supply means supplies plasma into the vacuum chamber along a first axis passing through the vacuum chamber. The object holding and rotating means rotates the object to be processed having a length in the direction of the second axis around the second axis orthogonal to the first axis in the vacuum tank. The plasma supply means has a hollow case, and the case is disposed outside the vacuum chamber, and the inside is in communication with the vacuum chamber via a communicating portion. The first axis passes through the inside of the housing. The housing is provided with an electron emission electrode which receives supply of electron emission power and emits electrons, and the electron emission electrode has a substantially linear shape provided parallel to the second axis on the first axis. is there. An electron acceleration electrode is provided between the electron emission electrode and the communication portion in the housing, facing the electron emission electrode at a distance. The electron acceleration electrode accelerates the electrons by receiving supply of electron acceleration power which is direct current power of positive potential with reference to the potential of the electron emission electrode. A discharge gas supply unit supplies a discharge gas, which is discharged by the collision of the accelerated electrons, into the housing. A magnetic field generating means is provided for generating a magnetic field in a direction along the first axis so that the plasma generated by the discharge of the discharge gas is supplied into the vacuum chamber along the first axis. Apply. The electron acceleration electrode has a substantially linear opening, and the opening extends in a direction parallel to the second axis on the first axis and penetrates in the direction along the first axis. . The communication portion has a substantially linear opening extending in a direction parallel to the second axis on the first axis. When the opening of the electron acceleration electrode and the opening of the communication portion are viewed from the distant position on the first axis, the electron acceleration electrode opening and the opening of the communication portion overlap each other. The peripheral edge of the opening of the communication portion is approximately equal to or larger than the opening of the electron acceleration electrode. The magnetic field generating means generates the magnetic field such that the magnetic field passes between one of the two ends along the second axis at the opening of the electron accelerating electrode and the other.

  That is, according to the present invention, plasma is supplied into the vacuum chamber along the first axis passing through the vacuum chamber. The plasma is directly irradiated to the surface of the object stored in the vacuum chamber. Then, the object to be processed rotates about a second axis orthogonal to the first axis, that is, rotates about the second axis orthogonal to the plasma supply direction. Furthermore, the cross section of the plasma along a plane orthogonal to the first axis, that is, the cross section of the plasma along a plane orthogonal to the supply direction of the plasma, is substantially straight in parallel with the second axis which is the rotation axis of the object is there. In short, a substantially linear plasma elongated in the direction along the second axis is irradiated onto the surface of the object to be processed which rotates about the second axis from the direction along the first axis orthogonal to the second axis. Be done. As a result, the surface of the object to be treated is uniformly irradiated with plasma, and a predetermined treatment using this plasma is uniformly applied over the entire surface of the object to be treated. Here, for example, when the number of objects to be processed is only one, it is desirable that the objects to be processed be disposed on the second axis. In this case, the object to be treated is, as it were, autorotated, and in particular, unlike the above-mentioned prior art, it does not revolve around the plasma. Therefore, according to the present invention, unlike the prior art, it is not necessary for the object to be treated to have a size that allows the object to revolve around the plasma, as a vacuum chamber in which the object to be treated is accommodated. And can cope with large-sized objects easily and flexibly.

The magnetic field generating means may include a substantially rectangular closed loop electromagnetic coil provided so as to surround the periphery of the housing. By this configuration, the magnetic field is generated so that the magnetic field passes between one of the two ends along the second axis at the opening of the electron acceleration electrode and the other.

  It is also possible to provide bias power supply means for supplying a bias power of a negative potential to the object with reference to the potential of the electron acceleration electrode.

Moreover, the wall surface in alignment with a 1st axis can also be provided over the perimeter perimeter of the above-mentioned communicating part. By this, a distance is placed between the inside of the vacuum chamber and the inside of the housing of the plasma supply means, and it becomes possible, for example, to form a pressure difference between the two. In particular, by forming a state in which the pressure in the housing of the plasma supply means is higher than the pressure in the vacuum tank, the influence of the atmosphere in the vacuum tank in the housing of the plasma supply means is suppressed. For example, in a configuration in which a material gas to be described later is supplied into the vacuum chamber, there is concern that the material gas may flow into the case of the plasma supply means to contaminate the inside of the case. Such a concern is suppressed by forming a state in which the pressure in the housing of the plasma supply means is higher than the pressure of .

  In addition, the object holding and rotating means may hold a plurality of objects along the circumferential direction of a circle centered on the second axis. In this case, it is desirable that each object to be processed be rotated about a third axis which is orthogonal to the circumferential direction of the circle and parallel to the second axis. According to this configuration, a plurality of objects to be processed can be processed simultaneously.

  And, in the present invention, a plurality of plasma supply means may be provided. For example, the plurality of plasma supply means may be provided along the outer peripheral direction of the second axis. According to this configuration, since the plurality of plasmas are irradiated from the plurality of plasma supply means to the surface of the object to be treated, the speed of the processing applied to the surface of the object to be treated is achieved. In other words, the time required for the process can be shortened.

  Also, for example, a plurality of plasma supply means may be provided along the extension direction of the second axis. According to this configuration, in particular, it is possible to cope with an object having a relatively large dimension in the extending direction of the second axis. Furthermore, for example, by disposing a plurality of objects to be processed along the extension direction of the second axis, it is also possible to simultaneously process the plurality of objects to be processed.

  As a predetermined process said here, there exists a film-forming process which produces | generates insulating coating films, such as a diamond like carbon (Diamond-Like Carbon: it is hereafter called "DLC") film | membrane, on the surface of to-be-processed object.

  In this case, it is desirable that the material gas to be the material of the insulating film be supplied in the vicinity of the supply portion of the plasma from the plasma supply means in the vacuum chamber. According to this configuration, the decomposition efficiency of the material gas by plasma is improved, and as a result, the generation efficiency (film forming rate) of the insulating film is improved.

  As described above, according to the present invention, it is possible to easily and flexibly cope with a large object to be treated. That is, wider response is possible compared to the prior art in which it is difficult to cope with a large object to be treated.

It is a figure showing the schematic structure which looked at the plasma surface treatment apparatus concerning one embodiment of the present invention from the side. It is a figure which shows the schematic structure which looked at the same plasma surface treatment apparatus from upper direction. It is a perspective view which shows the external appearance of the plasma gun in the embodiment. It is a figure which shows schematic structure of the same plasma gun. It is an illustration figure which looked at the state where the same plasma gun is operating from the side. It is an illustration figure which looked at the state where the same plasma gun is operating from the upper part. It is a graph which shows the experimental result in the embodiment. It is a graph which shows the experimental result different from FIG. FIG. 8 is a graph showing still another experimental result. FIG. 9 is a graph showing still another experimental result. FIG. 10 is a graph showing still another experimental result. FIG. 11 is a graph showing still another experimental result. It is an illustration figure which shows another example of the embodiment. It is an illustration figure which shows the example different from FIG. It is an illustration figure which shows another example different from FIG.

  One embodiment of the present invention will be described in detail below.

  As shown in FIG. 1, the plasma surface treatment apparatus 10 according to the present embodiment is provided with a substantially cylindrical vacuum chamber 12 closed at both ends. The vacuum chamber 12 is installed in a state where the portions corresponding to both ends of the cylindrical shape are directed up and down, that is, in a state where the central axis Xa of the cylindrical shape is extended in the vertical direction. The inner diameter of the vacuum chamber 12 is, for example, about 1100 mm, and the height dimension in the vacuum chamber 12 is, for example, about 800 mm. The shape and dimensions of the vacuum chamber 12 are merely an example, until it gets bored, and are appropriately determined in accordance with various conditions such as the size and the number of the object 100 to be described later. The vacuum chamber 12 itself is made of metal having high corrosion resistance and heat resistance, for example, stainless steel such as SUS304, and its wall portion is connected to a ground potential as a reference potential.

  An exhaust port 14 is provided at an appropriate position of the wall portion of the vacuum chamber 12, for example, at a position slightly outward (leftward in FIG. 1) of the center of the wall portion forming the lower surface. A vacuum pump (not shown) is connected to the exhaust port 14 via an exhaust pipe (not shown) outside the vacuum chamber 12. The vacuum pump also functions as a pressure control unit that controls the pressure Pc in the vacuum chamber 12. Further, an automatic pressure control device (not shown) is provided in the middle of the exhaust pipe, and this automatic pressure control device also functions as the pressure control means.

  Further, a plasma gun 16 as a plasma supply means is coupled to an appropriate position (right side in FIG. 1) outside the wall forming the side surface of the vacuum chamber 12. Specifically, referring also to FIG. 2, the plasma gun 16 has a substantially rectangular parallelepiped housing 18. The housing 18 is made of metal having high corrosion resistance and heat resistance, for example, stainless steel such as SUS304, as in the vacuum chamber 12, and the inside thereof communicates with the inside of the vacuum chamber 12. Here, for example, while assuming a straight line Xb orthogonal to the central axis Xa of the vacuum chamber 12 at a substantially central position in the height direction in the vacuum chamber 12, assuming that the straight line Xb is a horizontal axis, this horizontal axis Xb The housing 18 is coupled to the vacuum tank 12 so as to pass through the inside of the housing 18 via a communicating portion between the inside of the housing 18 and the inside of the vacuum tank 12. In other words, the interior of the vacuum chamber 12 and the interior of the housing 18 are linearly continuous along the horizontal axis Xb via the communication portion. The housing 18 is coupled to the vacuum chamber 12 through the substantially rectangular closed loop insulating member 20, that is, electrically insulated from the vacuum chamber 12, and thus has an insulation potential. Incidentally, in FIG. 2, some of the components shown in FIG. 1 including the ground potential are omitted for the sake of easy viewing.

  Focusing on the inside of the housing 18, the hot cathode 22 as an electron emission electrode and the anode 24 as an electron acceleration electrode are provided in the housing 18. Among them, the hot cathode 22 is, for example, a linear tungsten filament having a diameter of about 1 mm, and extends substantially perpendicularly to the above-mentioned horizontal axis Xb in a substantially central portion of itself. In other words, it is provided in parallel with the central axis Xa of the vacuum chamber 12. The thermal cathode 22 is connected to a DC power supply 26 as an electron emission power source outside the housing 18 (and the vacuum chamber 12), and the cathode as an electron emission power from the DC power supply 26. The power Ec is supplied and heated to 2000 ° C. or higher, which in turn emits thermions. The cathode power Ec is not limited to direct current power, and may be alternating current power. Further, although the detailed description is omitted, exactly two hot cathodes 22 are provided including the spare ones, and when the hot cathode 22 is broken (broken) during operation, the spare cathodes are automatically provided. It is devised to switch to

  On the other hand, the anode 24 is a substantially rectangular flat plate having a thickness of about 3 mm to 5 mm made of a high melting point metal such as molybdenum, and is more suitable for the vacuum chamber 12 than the hot cathode 22 on the horizontal axis Xb described above. It is provided so as to face the hot cathode 22 at a close position. Specifically, the anode 24 has an opening 24 a penetrating between its two main surfaces. The opening 24 a has an elongated linear shape extending in the longitudinal direction of the anode 24. Then, in the anode 24, the opening 24 a is orthogonal to the horizontal axis Xb at its central portion, and the opening 24 a extends in the vertical direction, in other words, the opening 24 a is parallel to the hot cathode 22. Furthermore, the opening 24a is provided so as to penetrate in the direction along the horizontal axis Xb. The anode 24 is connected to the ground potential outside the housing 18. At the same time, the anode 24 is connected to a DC power supply 28 as a power supply means for electron acceleration outside the housing 18, and the DC power supply 28 uses the potential of the hot cathode 22 as the anode power Ea as a reference. The above-mentioned thermal electrons are accelerated by receiving the supply of direct current power of positive potential.

  Then, an aperture 30 having a wall surface along the horizontal axis Xb is provided in the communication portion of the housing 18 with the inside of the vacuum chamber 12. Specifically, referring to FIG. 3 and FIG. 4 together, the aperture 30 has an opening 30 a shaped like projecting the opening 24 a of the anode 24 in the direction along the horizontal axis Xb, ie, It has an elongated linear opening 30 a similar to the opening 24 a of the anode 24. The dimension in the vertical direction of the opening 30 a of the aperture 30, that is, the so-called length dimension La is equal to or greater than the length dimension Lb of the opening 24 a of the anode 24 (LaLLb), preferably the opening 24 a of the anode 24. And the length dimension Lb (La Lb). The dimension in the horizontal direction of the opening 30a of the aperture 30, that is, the so-called width dimension Lc is equal to or greater than the width dimension Ld of the opening 24a of the anode 24 (Lc L Ld), preferably in the opening 24a of the anode 24 It is approximately equal to the length dimension Ld (Lc ≒ Ld). Further, the dimension in the direction along the horizontal axis Xb of the opening 30a of the aperture 30, that is, the so-called depth dimension Le is appropriately determined in accordance with the situation of each occasion. The aperture 30 is also made of metal having high corrosion resistance and heat resistance, for example, stainless steel such as SUS304, similarly to the housing 18, and is electrically insulated.

  Furthermore, a substantially rectangular closed loop electromagnetic coil 32 as magnetic field application means is provided outside the housing 18 so as to surround the circumference of the housing 18 around the horizontal axis Xb. Particularly, as shown in FIG. 4 (d), the electromagnetic coil 32 is positioned at the center of its own center between the hot cathode 22 and the anode 24 (strictly between the respective surfaces) in the direction along the horizontal axis Xb. It is arranged to be. The electromagnetic coil 32 is connected to a DC power supply device as a magnetic field application power supply means (not shown) outside the housing 18 and supplies DC power Em as a magnetic field application power from the DC power supply device. In response, a mirror magnetic field is formed in the housing 18, and in detail, a magnetic field 200 described later in the direction along the horizontal axis Xb is applied. The magnetic field 200 acts not only in the housing 18 but also in the vacuum chamber 12. In FIG. 3 and FIG. 4, the electromagnetic coil 32 is shown by a broken line in consideration of easy viewing.

  Incidentally, the length dimension (effective length) Lf of the hot cathode 22 is, for example, 400 mm. The length dimension Lb of the opening 24 a of the anode 24 is approximately equal to the length dimension Lf of the hot cathode 22 (Lb ≒ Lf) or slightly smaller than the length dimension Lf of the hot cathode 22 (Lb <Lf) , For example, 400 mm. The width Ld of the opening 24a of the anode 24 is much smaller than the length Lb of the opening 24a, and the ratio Ld: Lb is about 1: 2 to 1:20, for example, 30 mm. . The distance Lg between the hot cathode 22 and the anode 24 in the direction along the horizontal axis Xb is, for example, about 80 mm. Strictly speaking, although the opening 24a of the anode 24 is a so-called long round hole whose both ends are circular, it is not limited to this and it may be an elongated slit, for example, even if it is an elongated rectangular hole Good. The same applies to the opening 30 a of the aperture 30. Although not shown, a constant tension is applied to the lower end of the hot cathode 22 in the lengthwise direction of the hot cathode 22 to absorb deformation (deflection) caused by heating the hot cathode 22. A weight as a tension applying means is attached.

  Subsequently, focusing on the inside of the vacuum chamber 12, a plurality of objects to be processed 100, 100,... Are disposed in the vacuum chamber 12. Specifically, the objects to be treated 100, 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 object to be treated 100 is, for example, an elongated cylindrical member such as a drill blade, and extends in the vertical direction, that is, in the direction along the central axis Xa of the vacuum chamber 12 It is held by a holder 34 as holding means. Each holder 34 is coupled via a gear mechanism 36 near the periphery of a disc-shaped revolving base 38. The center of the revolving base 38 is located on the central axis Xa of the vacuum chamber 12, and at the center of the revolving base 38, one end of the rotary shaft 40 extending along the central axis Xa of the vacuum chamber 12 It is fixed. The other end of the rotating shaft 40 is coupled to a shaft 42 a of a motor 42 as a rotational driving means outside the vacuum chamber 12.

  That is, when the motor 42 is driven and the shaft 42a of the motor 42 rotates, for example, in the direction indicated by the arrow 44 in FIG. 1, the revolving base 38 rotates in the same direction, that is, in the direction indicated by the arrow 46 in FIG. Do. Along with this, each object to be treated 100 rotates about the central axis Xa of the vacuum chamber 12 and, as it were, revolves. At the same time, each holder 34 is rotated about a vertical line Xc passing through itself in a direction shown by an arrow 48 in each of FIG. 1 and FIG. And with rotation of this holder 34 itself, the to-be-processed object 100 also rotates in the same direction, so to say, it autorotates. In addition, the diameter (PCD; Pitch Circle Diameter) of the revolution path of the to-be-processed object 100 is about 600 mm, for example. And the revolution speed (rotational speed of the revolving base 38) of the to-be-processed object 100 is 0.5 rpm-1 rpm, for example. On the other hand, the rotation speed (rotational speed of the holder 34 itself) 100 of the workpiece 100 is, for example, 30 rpm to 60 rpm, that is, 60 times the revolution speed.

  In addition, bias power from the pulse power supply device 50 as bias power supply means outside the vacuum chamber 12 is applied to each of the objects to be processed 100 via the holder 34, the gear mechanism 36, the revolving base 38 and the rotary shaft 40. Asymmetrical pulse power Eb is supplied as The voltage value of the asymmetrical pulse power Eb alternates between a high level of +37 V and a low level VL of -37 V or less, and among these, the low level voltage value can be arbitrarily adjusted. Further, the frequency and duty ratio (the ratio of the high level period in one cycle) of the asymmetric pulse power Eb can also be arbitrarily adjusted. The average voltage value (DC conversion value) of the asymmetrical pulse power Eb, that is, the so-called bias voltage Vb can be arbitrarily adjusted by the low level voltage value, frequency and duty ratio of the asymmetrical pulse power Eb.

  Also, magnetron sputtering is performed in the vicinity of a wall forming a side surface in the vacuum chamber 12 and at a position (a position on the left side in FIGS. 1 and 2) outside the revolution path of each object 100 to be processed. The cathode 52 is disposed. The magnetron sputtering cathode 52 has a flat target 54 disposed toward the central axis Xa of the vacuum chamber 12 and a back surface of the target 54 (surface facing away from the central axis Xa of the vacuum chamber 12). A magnet 56 provided in close proximity to the target 54 and a protective cover 58 covering the target 54 and the magnet 56 while exposing the surface (so-called sputtered surface) of the target 54 are provided. Among them, the target 54 is made of, for example, chromium (Cr) having a purity of 99.9% or more, and its height dimension is about 700 mm, its width dimension is about 140 mm, and its thickness dimension is about 10 mm. The target 54 is supplied with DC power of negative potential as target power from a sputtering power supply device (not shown) outside the vacuum chamber 12. The magnet 56 is for improving the sputtering efficiency of the target 54, and although a detailed illustration is omitted, a permanent magnet and a yoke are appropriately combined. The protective cover 58 is for protecting the target 54 and the magnet 56 other than the sputtered surface of the target 54, is also made of metal having high corrosion resistance and heat resistance, and is made of stainless steel such as SUS 304, for example. .

  Furthermore, at an appropriate position in the vacuum chamber 12, an electric heater as temperature control means (not shown) is provided. The electric heater is for heating the inside of the vacuum chamber 12 including the respective objects to be treated 100. The heating temperature is controlled by heater heating power supplied from a heater heating power supply device (not shown) outside the vacuum chamber 12.

Although not shown in detail, a source gas supply path for supplying source gas is provided in the vacuum chamber 12, preferably at a position near the opening 30 a of the aperture 30 of the plasma gun 16 described above. As the material gas referred to here, there are, for example, hydrocarbon gas and silicon gas, and in particular, acetylene gas and TMS (Tetra-Methyl Silane; Si (CH ₃ ) ₄ ) gas. The material gas supply passage includes an open / close valve as an opening / closing means for opening / closing the supply passage, and a mass flow controller as a flow control means for controlling the flow rate of the material gas flowing through the supply passage. Is provided. The hydrocarbon gas includes methane (CH ₄ ) gas, ethylene (C ₂ H ₄ ) gas, benzene (C ₆ H ₆ ), etc. in addition to acetylene gas, but from the viewpoint of safety and cost And acetylene gas are most suitable. In addition to TMS gas, there are silane (SiH ₄ ) gas and methylsilane (SiH ₃ (CH ₃ )) etc. as a silicon-based gas, but also from the viewpoint of safety and cost, TMS gas is the most suitable. is there.

Further, although not shown in detail, a discharge gas supply passage for supplying a discharge gas is provided in the housing 18 of the plasma gun 16, preferably at a position near the hot cathode 22. As a discharge gas said here, there exists argon gas, for example. Then, a hydrogen (H ₂ ) gas as a cleaning gas to be described later and a nitrogen (N ₂ ) gas as a reaction gas are also supplied using this discharge gas supply path. The discharge gas supply path is also provided with an open / close valve as an open / close means and a mass flow controller as a flow rate control means.

Similarly, although not shown in detail, in order to supply an oxygen (O ₂ ) gas as a contaminant removal gas to be described later into the housing 18 of the plasma gun 16, preferably at a position distant from the hot cathode 22. And a gas supply path for removing contaminants. The contaminant removal gas supply path is also provided with an on-off valve as an open / close unit and a mass flow controller as a flow rate control unit.

  In addition, in order to cover the entire area around the portion of the wall surface in the vacuum chamber 12 to which the plasma gun 16 is coupled and not to interfere with the aperture 30 (so as not to block the opening 30a of the aperture 30) An approximately plate-like plasma stabilization electrode 60 is provided as a plasma stabilization means. The plasma stabilizing electrode 60 is made of a relatively lightweight metal, such as titanium (Ti) or aluminum (Al) alloy, which is high in corrosion resistance and heat resistance, and has an electrically insulating potential. There is.

  In particular, as shown in FIG. 2, the portion 12 a of the wall of the vacuum chamber 12 to which the plasma gun 16 is connected has a structure suitable for the plasma gun 16 to be connected, desirable. In this case, it is desirable that the portion 12a be able to be opened and closed like a sliding door or a door in consideration of the workability at the time of maintenance of the plasma gun 16 or the like. The same applies to the portion 12 b of the wall of the vacuum chamber 12 where the magnetron sputtering cathode 52 is disposed.

  The plasma surface treatment apparatus 10 having such a configuration is used, for example, to form a DLC film on the surface of the object 100 to be treated. In addition, since it is difficult to form a DLC film directly on the surface of the object to be treated 100 in particular in terms of adhesion, an intermediate layer and a graded layer were formed in this order to give the adhesion. After that, a DLC film is formed. In particular, the intermediate layer is a so-called sandwich structure in which a chromium layer, a chromium nitride (CrN) layer and a chromium layer are formed in this order. The graded layer is a silicon-containing carbon (SiC x) layer containing carbon (C) as the main component and containing silicon (Si), and the content of silicon increases with distance from the surface (intermediate layer) of the object 100 to be treated. It is generated to be smaller.

For this series of surface treatments, first, the object to be treated 100 is accommodated in the vacuum chamber 12, and then the inside of the vacuum chamber 12 is evacuated by the vacuum pump. For example, the pressure Pc in the vacuum chamber 12 is 2 It is exhausted until it becomes about ^10-3 Pa. Then, after the so-called evacuation, the motor 42 is driven to start the self-revolution of the respective processing objects 100. Further, heater heating power is supplied to the above-described electric heater, and the inside of the vacuum chamber 12 is heated to, for example, about 120.degree. Thereby, the impurity gas contained in each to-be-processed object 100 is discharged | emitted, and what is called a degassing process is performed.

  After the degassing process is performed for a predetermined period, the supply of the heater heating power to the electric heater is stopped, and then the discharge cleaning process is performed. In the discharge cleaning process, the cathode power Ec is supplied to the hot cathode 22 and the anode power Ea is supplied to the anode 24. Then, the hot cathode 22 is heated to emit hot electrons from the hot cathode 22, and the hot electrons are accelerated toward the anode 24. In this state, when argon gas as a discharge gas is supplied into the housing 18 of the plasma gun 16, accelerated thermal electrons collide with particles of argon gas, and the impact ionizes argon gas particles. As a result, plasma 300 is generated. Furthermore, when hydrogen gas as a cleaning gas is supplied into the housing 18 of the plasma gun 16, the particles of the hydrogen gas are also ionized to be plasma 300 and ionized. The supply of argon gas and hydrogen gas may be performed simultaneously.

Then, when the power Em for applying a magnetic field is supplied to the electromagnetic coil 32, the above-mentioned mirror magnetic field is formed in the housing 18 of the plasma gun 16, and more specifically, as shown by dashed arrow 200 in FIGS. A magnetic field in the direction along the axis Xb is applied. Then, the thermal electrons spirally move to wind around the magnetic field 200. As a result, the number and probability of the thermal electrons colliding with the argon gas particles and the hydrogen gas particles are increased, and the density of the plasma 300 is improved. The plasma 300 flows along the magnetic field 200 and is supplied into the vacuum chamber 12 through the opening 30 a of the aperture 30. At this time, the plasma 300 has a shape corresponding to the opening 24 a of the anode 24 by passing through the opening 24 a of the anode 24 . Specifically, in a plane perpendicular to the horizontal axis Xb, the cross section of the plasma 300 is in the form of an elongated, substantially straight line extending in the vertical direction. Then, the substantially linear plasma 300 is supplied into the vacuum chamber 12 while maintaining its shape by passing through the opening 30 a of the aperture 30. Here, focusing on the aperture 30, the aperture 30 is electrically insulated as described above. A closed loop anode 24 is disposed between the aperture 30 and the hot cathode 22. Furthermore, the magnetic field 200 is applied in the direction along the horizontal axis Xb, which is the arrangement axis. In short, the plasma gun 16 in this embodiment also constitutes the above-described PIG discharge mechanism.

  In the vacuum chamber 12, each object to be treated 100 is self-revolving, so the plasma 300 supplied to the inside of the vacuum chamber 12 is directly applied to the surface of the material 100 being self-revolving. It is irradiated. Moreover, since the plasma 300 irradiated to the surface of the object to be treated 100 is substantially linear in parallel with the self-revolution axes Xa and Xc of the object to be treated 100, the entire surface of the object to be treated 100 is evenly irradiated. Ru. In this state, when the bias power Eb is supplied to the workpiece 100, argon ions and hydrogen ions in the plasma 300 are positively incident on the surface of the workpiece 100. Then, impurities on the surface of the object to be treated 100 are removed by the sputtering action by argon ions and the chemical reaction action by hydrogen ions, and so-called discharge cleaning treatment is performed.

The anode 24 in the housing 18 of the plasma gun 16, which is a generation source of the plasma 300, is connected to the ground potential as described above. The anode 24 is supplied with direct current anode power Ea of positive potential based on the potential of the hot cathode 22. Thereby, the space potential in the housing 18, that is, the potential of the plasma 300 is stabilized on the basis of the ground potential. The strength of the plasma 300, that is, the output Wg of the plasma gun 16 is the magnitude of the cathode power Ec supplied to the hot cathode 22 (the heating temperature of the hot cathode 22) and the magnitude of the anode power Ea supplied to the anode 24. It depends on the

  Further, for example, even if the position of the hot cathode 22 and the position of the anode 24 are opposite to each other, the plasma 300 is generated. However, in this case, since the hot cathode 22 is present in the vicinity of the opening 30 a of the aperture 30, that is, in the direction in which the plasma 300 is supplied, the consumption of the elongated hot cathode 22 becomes remarkable. In addition, acetylene gas as a material gas flows into the housing 18 of the plasma gun 16 through the opening 30 a of the aperture 30 in a film forming process for forming a DLC film described later, and is contained in the acetylene gas. The carbon component carbonizes the hot cathode 22 and may damage the hot cathode 22. In order to suppress this, it is desirable that the hot cathode 22 be provided at a position opposite to the direction in which the plasma 300 is supplied, that is, at a position farther from the opening 30 a of the aperture 30 than the anode 24.

  Furthermore, electrons in the plasma 300 supplied from the plasma gun 16 into the vacuum chamber 12 try to flow into the wall surface in the vacuum chamber 12 at the same potential (ground potential) as the anode 24, and in particular, the plasma gun 16 Try to flow around the part being However, as described above, since a region around the portion of the wall surface in the vacuum chamber 12 to which the plasma gun 16 is coupled is covered by the plasma stabilization electrode 60 set to the insulating potential, electrons in the plasma 300 are Even if it tries to flow into the wall surface in the vacuum chamber 12, its progress is blocked by the plasma stabilization electrode 60. Therefore, the wall surface of the vacuum chamber 12 does not act as an electrode, and as a result, the plasma 300 is further stabilized.

  After the discharge cleaning process is performed for a predetermined period, the supply of hydrogen gas is stopped, and then the film forming process by the sputtering method for generating the above-described intermediate layer is performed. First, target power is supplied to the target 54 of the magnetron sputtering cathode 52. Then, argon ions in the plasma 300 collide with the sputtering surface of the target 54, and the chromium particles are struck (sputtered) from the sputtering surface by the impact. The struck chromium particles collide with the surface of the object 100 to be deposited. Thereby, a chromium layer is generated on the surface of the object 100 to be treated. Then, after the chromium layer having a necessary thickness is generated, nitrogen gas as a reaction gas is supplied into the housing 20 of the plasma gun 16. Then, the particles of nitrogen gas are ionized to generate nitrogen ions. The nitrogen ions collide with the surface of the object to be treated 100 and, strictly speaking, the chromium layer previously generated. At the same time, the chromium particles ejected from the target 54 also collide with the chromium layer. As a result, a chromium nitride layer, which is a compound of nitrogen and chromium, is formed on the chromium layer. Then, after the chromium nitride layer having a necessary thickness is generated by the so-called reactive sputtering method, the supply of nitrogen gas is stopped. Thereby, a chromium layer is generated anew. Then, the chromium layer having the necessary thickness is generated, and the intermediate layer is completed, and then the supply of the target power to the target 54 is stopped.

  Subsequently, a film forming process by plasma CVD is performed to generate the above-described inclined layer. That is, acetylene gas and TMS gas as material gases are supplied into the vacuum chamber 12. Then, these acetylene gas and TMS gas particles are ionized, carbon ions are generated from the acetylene gas particles, and silicon ions are generated from the TMS gas particles. Then, these carbon ions and silicon ions collide with the surface of the object to be processed 100 and, strictly speaking, collide with the intermediate layer generated earlier. Thus, a silicon-containing carbon layer, which is a compound of carbon and silicon, is formed on the intermediate layer. Further, the flow rate of acetylene gas supplied into the vacuum chamber 12 is gradually increased as time passes, and the flow rate of TMS gas supplied into the vacuum chamber 12 is gradually decreased as time passes. As a result, the silicon content in the silicon-containing carbon layer gradually decreases with the passage of time, that is, gradually decreases with distance from the surface (intermediate layer) of the workpiece 100. This results in the formation of a graded layer. The silicon content (Si / (Si + C)) in this graded layer is, for example, suitably about 20% to 40% in atomic number ratio in the lowermost layer on the intermediate layer side, and 0% to 4% in the uppermost layer The degree is appropriate.

  And the film-forming process by plasma CVD method for producing | generating DLC film is performed. That is, supply of TMS gas into the vacuum chamber 12 is stopped, and acetylene gas is supplied into the vacuum chamber 12 at a constant flow rate. Then, particles of acetylene gas are ionized, and carbon ions generated by the ionization collide with the surface of the object to be treated 100 and, strictly speaking, collide with the gradient layer generated earlier. Thereby, a DLC film which is a hard carbon film is generated on the inclined layer. In addition, since this DLC film is made of a hydrocarbon-based gas called acetylene gas, it inevitably contains hydrogen. The hydrogen content of this DLC film depends on the conditions (film forming conditions) at the time of formation of the DLC film, and in particular, depends on the output Wg of the plasma gun 16, the bias power Eb and the flow rate of acetylene gas. The hydrogen content is also related to the hardness and internal stress of the DLC film. For example, the lower the hydrogen content, the higher the hardness of the DLC film, but on the other hand, the internal stress of the DLC film becomes larger, and the adhesion is lowered. On the contrary, the higher the hydrogen content, the smaller the internal stress of the DLC layer and the better the adhesion, but the lower the hardness of the DLC film. From these facts, the hydrogen content of the DLC film is, for example, suitably 20% to 40% in atomic ratio, and preferably 25% to 35%. Furthermore, in the film forming process for generating the DLC film, the acetylene gas flows into the housing 18 of the plasma gun 16 to deposit carbon on the inner wall of the housing 18, and the inside of the housing 18. It is a concern that the In order to suppress the contamination in the housing 18, oxygen gas as a contaminant removal gas is supplied into the housing 18. The oxygen gas reacts with the carbon deposited in the housing 18 to form carbon dioxide, which is exhausted to the outside by a vacuum pump.

  When the DLC film of the required thickness is formed, the supply of acetylene gas into the vacuum chamber 12 is stopped and the supply of argon gas is stopped. At the same time, the supply of the cathode power Ec to the hot cathode 22 is stopped, and the supply of the anode power Ea to the anode 24 is stopped. Further, the supply of the bias power Eb to the object to be processed 100 is stopped, and the supply of the power Em for applying a magnetic field to the electromagnetic coil 32 is stopped. Then, while the pressure in the vacuum chamber 12 is gradually returned to near atmospheric pressure, a constant cooling period is set. Thereafter, the drive of the motor 42 is stopped, and the revolution of the object 100 is stopped. Then, the object to be treated 100 is taken out of the vacuum chamber 12 to complete a series of surface treatments.

  By the way, although the plasma 300 supplied from the plasma gun 16 into the vacuum chamber 12 is an elongated substantially linear shape extending in the vertical direction in the plane orthogonal to the horizontal axis Xb as described above, the magnetic field supplied to the electromagnetic coil 32 The shape of the plasma 300 changes depending on the magnitude of the application power Em. Specifically, as the magnetic field application power Em is larger, the diffusion angle θa of the plasma 300 in the vertical direction (strictly speaking, the vertical plane including the horizontal axis Xb) shown in FIG. 5 is smaller, and the horizontal shown in FIG. The diffusion angle θb of the plasma 300 in the direction (strictly speaking, the horizontal plane including the horizontal axis Xb) also decreases, so to say, the plasma 300 is narrowed. On the other hand, as the magnetic field application power Em is smaller, the diffusion angles θa and θb of the plasma 300 in the vertical direction and the horizontal direction are larger, so the plasma 300 is spread. In particular, when the diffusion angle θb of the plasma 300 in the horizontal direction is relatively large, the plasma 300 has a substantially rectangular shape rather than a substantially linear shape. In short, it is possible to control the shape of the plasma 300 by the magnitude of the magnetic field application power Em. Incidentally, the magnetic flux density B at the center (the center between the hot cathode 22 and the anode 24 on the horizontal axis Xb) in the housing 18 of the plasma gun 16 is, for example, 20 G ̃ depending on the magnitude of the power Em for electromagnetic application. It changes in the range of 100G.

  As described above, the plasma 300 is supplied from the plasma gun 16 into the vacuum chamber 12 through the opening 30 a of the aperture 30, and the supply efficiency is determined by the dimension La × Lc × Le of the opening 30 a of the aperture 30. It depends on The following experiment was conducted to verify this.

  First, a Faraday cup (not shown) is installed at the center of the vacuum chamber 12 (the intersection of the central axis Xa and the horizontal axis Xb) in a state of facing the plasma gun 16 (the opening 30a of the aperture 30). Then, after evacuating the inside of the vacuum chamber 12, argon gas is supplied into the inside of the vacuum chamber 12 (in the housing 18) to maintain the pressure Pc in the vacuum chamber 12 at 0.2 Pa. Then, the cathode power Ec is supplied to the hot cathode 22, the anode power Ea is supplied to the anode 24, and the magnetic coil 32 is supplied with the magnetic field application power Em to generate the plasma 300. Then, the voltage of the anode power Ea, that is, the anode voltage Va is set to 50 V (constant). At the same time, the current flowing through the electromagnetic coil 32 due to the supply of the magnetic field application power Em, that is, the coil current Im is set to 10 A (constant). According to the coil current Im of 10 A, the magnetic flux density B at the center of the housing 18 of the plasma gun 16 is about 60 G. In this state, by appropriately changing the cathode power Ec, the current flowing from the hot cathode 22 to the anode 24 (strictly speaking, the anode 24 and the ground potential), that is, the so-called discharge current Id is appropriately changed. The ion current density Js at the center of the vacuum chamber 12 is measured based on the output of the Faraday cup. This measurement was performed on four types of apertures 30 in which the dimensions La × Lc × Le of the apertures 30 are different from one another. The results are shown in FIG.

  As shown in FIG. 7, the ion current density Js at the center of the vacuum chamber 12 is larger as the discharge current Id is larger for any of the four types of apertures 30. Then, if the discharge current Id is constant, the larger the width dimension Lc of the opening 30a of the aperture 30, and the smaller the depth dimension Le of the opening 30a, the larger the ion current density Js, that is, the vacuum from the plasma gun 16 The result was obtained that the supply efficiency of the plasma 300 into the tank 12 is high. However, as the width dimension Lc of the opening 30 a of the aperture 30 is larger and the depth dimension Le of the opening 30 a is smaller, when the material gas is supplied into the vacuum chamber 12, the material gas is supplied to the plasma gun 16. It was found that the powder easily flowed into the housing 18 and the contamination in the housing 18 by the material gas became remarkable. On the other hand, although the supply efficiency of the plasma 300 from the plasma gun 16 into the vacuum chamber 12 decreases as the width dimension Lc of the opening 30a of the aperture 30 decreases and the depth dimension Le of the opening 30a increases, for example, vacuum A pressure differential can be created between the interior of the vessel 12 and the enclosure 18 of the plasma gun 16. In particular, when the material gas is supplied into the vacuum chamber 12 by forming a state in which the pressure Pg in the housing 18 of the plasma gun 16 is higher than the pressure Pc in the vacuum chamber 12, the material gas is plasma It is possible to suppress the flow of the gas into the housing 18 of the gun 16 and, consequently, the contamination of the inside of the housing 18 with the material gas can be suppressed. Taking these into consideration comprehensively, according to the experimental results shown in FIG. 7, it is concluded that the dimension La × Lc × Le of the opening 30 a of the aperture 30 is, for example, 400 mm × 30 mm × 75 mm most suitable. It reached.

  In addition, although the plasma 300 is an elongated substantially straight line extending in the vertical direction in the plane orthogonal to the horizontal axis Xb as described above, the following experiment was conducted to verify this.

  First, the Faraday cup is installed at each of a plurality of different positions on the central axis Xa in the vacuum chamber 12 so as to be horizontally directed to the plasma gun 16 (the opening 30a of the aperture 30). Then, as in the above-described experiment, after vacuuming the inside of the vacuum chamber 12, argon gas is supplied to the inside of the vacuum chamber 12 (in the housing 18) to set the pressure Pc in the vacuum chamber 12 to 0.2 Pa. maintain. Then, the cathode power Ec is supplied to the hot cathode 22, the anode power Ea is supplied to the anode 24, and the magnetic coil 32 is supplied with the magnetic field application power Em to generate the plasma 300. Here, the anode voltage Va is set to 50 V (constant), and the discharge current Id is set to 40 A (constant), that is, the output Wg of the plasma gun 16 is set to 2 kW. Then, the coil current Im was appropriately changed, and the ion current density Js at each position on the central axis Xa in the vacuum chamber 12 was measured based on the output of each Faraday cup at this time. The results are shown in FIG. The horizontal axis in FIG. 8 represents each position on the central axis Xa by the distance in the vertical direction (height direction) starting from the holding portion of the object to be processed 100 by the holder 34. Therefore, the Faraday cup can not be installed in the vicinity of the holding portion of the holder 34 which is the base point, and hence the position closest to the base point is about 90 mm.

  As shown in FIG. 8, as the coil current Im is larger, the ion current density Js at each position is larger. On the other hand, the larger the coil current Im, the more the difference in ion current density Js occurs between each position, and in particular, the ion current density Js near both ends (especially the position of 450 mm on the horizontal axis) is the ion current density Js near the center It becomes significantly smaller than that. This is because, as described with reference to FIG. 5, as the coil current Ib (power for applying magnetic field Em) increases, the diffusion angle θa of the plasma 300 in the vertical direction decreases, that is, the plasma 300 is narrowed. It is thought that it originates in ,. According to the experimental results shown in FIG. 8 including this, when the coil current Im is 10 A or less, the distance from the position of the holding portion of the holder 34 on the central axis Xa in the vacuum chamber 12 to the position of approximately 400 mm In the range, it is assumed that the ion current density Js is approximately uniform, that is, the density of the plasma 300 is approximately uniform. The dimension of 400 mm referred to here is equivalent to the length dimension Lf of the hot cathode 22, and is equivalent to the length dimension Lb of the opening 24a of the anode 24. That is, it can be said that the density of the plasma 300 in the vertical direction is substantially uniform over the same range as the length dimension Lf of the hot cathode 22 and the length dimension Lb of the opening 24 a of the anode 24.

  Subsequently, the density of the plasma 300 in the horizontal direction is verified. First, a straight line orthogonal to the central axis Xa of the vacuum chamber 12 and orthogonal to the above-mentioned horizontal axis Xb is assumed. And the Faraday cup is installed in the state which turned horizontally at the plasma gun 16 (opening part 30a of the aperture 30) side in each of several mutually different positions on this virtual straight line. Then, after vacuuming the inside of the vacuum chamber 12 as described above, argon gas is supplied to the inside of the vacuum chamber 12 (in the housing 18) to maintain the pressure Pc in the vacuum chamber 12 at 0.2 Pa. . Then, the cathode power Ec is supplied to the hot cathode 22, the anode power Ea is supplied to the anode 24, and the magnetic coil 32 is supplied with the magnetic field application power Em to generate the plasma 300. Then, the anode voltage Va is set to 50 V (constant), and the discharge current Id is set to 40 A (constant), that is, the output Wg of the plasma gun 16 is set to 2 kW. In this state, the coil current Im was appropriately changed, and the ion current density Js at each position on the virtual straight line in the vacuum chamber 12 was measured based on the output of the Faraday cup at this time. The results are shown in FIG. The horizontal axis in FIG. 9 represents each position on the virtual straight line by the distance in the horizontal direction (in other words, the left and right direction) along the virtual straight line starting from the central axis Xa (or the horizontal axis Xb).

  As shown in FIG. 9, the larger the coil current Im, the larger the ion current density Js at each position. Then, at a position on the central axis Xa, the ion current density Js is the largest and shows a so-called peak, and the position farther from the central axis Xa, the smaller the ion current density Js. This means that the dimension of the plasma 300 is small in the direction along the imaginary straight line, that is, in the left-right direction. In short, it is confirmed from the experimental results shown in FIG. 9 and the above-described experimental results shown in FIG. 8 that the plasma 300 is an elongated substantially straight line extending in the vertical direction in a plane orthogonal to the horizontal axis Xb. The

  Next, a DLC film was actually produced by the plasma surface treatment apparatus 10 of the present embodiment, and this DLC film was evaluated.

  First, a disc made of chromium molybdenum steel (SCM 415) having a diameter of 30 mm and a thickness dimension of 3 mm is prepared as the object to be treated 100. Then, a 50 mm × 50 mm × 500 mm prismatic jig is attached to each holder 30 so as to extend in the vertical direction, and one side of the object to be treated 100 is provided on the substantially central side face in the length direction of this jig. Paste the main surface. Then, after the inside of the vacuum chamber 12 is evacuated, the above-mentioned electric heater is heated to about 120 ° C., and the degassing process is performed for about 30 minutes. Then, the heating of the electric heater is stopped, and then the discharge cleaning process is performed.

  In this discharge cleaning process, the supply flow rate of argon gas is 50 mL / min, and the supply flow rate of hydrogen gas is 50 mL / min. Then, the pressure Pc in the vacuum chamber 12 is maintained at 0.2 Pa. Further, the anode voltage Va is 50 V, and the discharge current Id is 20 A, that is, the output Wg of the plasma gun 16 is 1 kW. Further, the coil current Im is 10 A, that is, the magnetic flux density B at the center of the housing 18 of the plasma gun 16 is about 60 G. In addition, the bias voltage Vb is −600 V, the frequency of the bias power Eb is 100 kHz, and the duty ratio of the bias power Eb is 30%. Under this condition, the discharge cleaning process is performed for 20 minutes. Then, the supply of hydrogen gas is stopped, and subsequently, a film forming process is performed to generate an intermediate layer.

  In the film forming process for generating the intermediate layer, the flow rate of argon gas is set to 200 mL / min, and the pressure Pc in the vacuum chamber 12 is maintained at 0.5 Pa. Then, the target power supplied to the target 54 of the magnetron sputtering cathode 52 is 8 kW. Furthermore, the bias voltage Vb is set to -100V. The frequency and duty ratio of the bias power Eb, the anode voltage Va, the discharge current Id, and the coil current Im are the same as in the discharge cleaning process. Under this condition, a chromium layer is formed, which is performed for 10 minutes. This produces a chromium layer of about 0.15 μm in thickness. Then, a chromium nitride layer is generated by supplying nitrogen gas at a flow rate of 50 mL / min, which is performed for 40 minutes. This produces the said chromium nitride layer whose thickness is about 0.7 micrometer. Furthermore, the supply of nitrogen gas is stopped, and a chromium layer is again formed, which is performed for 10 minutes. This produces a chromium layer of about 0.15 μm in thickness. That is, an intermediate layer having a thickness of about 1 μm consisting of a chromium layer, a chromium nitride layer and a chromium layer is formed. Then, the supply of the target power to the target 54 is stopped, and subsequently, the film forming process for generating the inclined layer is performed.

  In the film forming process for generating the inclined layer, the flow rate of argon gas is 50 mL / min. Then, the anode voltage Va is set to 50 V, and the discharge current Id is set to 10 A, that is, the output Wg of the plasma gun 16 is set to 500 W. Further, the bias voltage Vb is set to -600V. The frequency and duty ratio of the bias power Eb and the coil current Im are the same as in the film forming process for generating the intermediate layer. Then, acetylene gas is supplied, and the flow rate is continuously (or stepwise) increased from 150 mL / min to 300 mL / min over a period of 15 minutes. At the same time, TMS gas is supplied, and the flow rate is reduced continuously (or stepwise) from 60 mL / min to 30 mL / min over the same time of 15 minutes. During this time, the pressure Pc in the vacuum chamber 12 is maintained at 0.3 Pa. This produces a graded layer about 0.3 μm thick. Then, the supply of the TMS gas is stopped, and subsequently, a film forming process for generating a DLC film is performed.

  In the film forming process for forming a DLC film, the flow rate of argon gas is 50 mL / min, and the flow rate of acetylene gas is 300 mL / min. In addition, oxygen gas is supplied at a flow rate of 20 mL / min. Then, the pressure Pc in the vacuum chamber 12 is maintained at 0.2 Pa. Further, the anode voltage Va is 50 V, and the discharge current Id is 40 A, that is, the output Wg of the plasma gun 16 is 2 kW. Then, the bias voltage Vb is set to -100V. The frequency and duty ratio of the bias power Eb and the coil current Im are the same as in the film forming process for generating the inclined layer. This produces a DLC film having a thickness of about 3 μm. Then, a series of surface treatments are finished.

  The surface treatment is repeated in the same manner as this, and only the bias voltage Vb is changed in the film forming process for forming the final DLC film. Specifically, the bias voltage Vb is set to -200V, -300V, -400V, -500V and -600. And, so-called tribological evaluation was performed on the DLC film generated under each condition. FIG. 10 shows the evaluation results of Knoop hardness. And the evaluation result of a specific abrasion loss is shown in FIG. In addition, evaluation of the specific abrasion loss which concerns on FIG. 11 was performed in air | atmosphere and under a non-lubricated environment using a reciprocating slide tester. The ball of this reciprocating sliding tester is made of 1/4 inch SUJ2, and the applied load on the ball is 1000 g. The sliding speed is 300 mm / min, and the stroke is 5 mm. In addition, the number of cycles is 10000 and the sliding time is 6 hours. And the contact stress of Hertz at the initial stage of sliding is 1.3 GPa.

  As shown in FIG. 10, the larger the bias voltage Vb (the absolute value thereof), the higher the Knoop hardness of the DLC film, that is, the higher the hardness of the DLC film is obtained. Then, as shown in FIG. 11, the larger the bias voltage Vb (the absolute value of the bias voltage Vb), the smaller the specific wear amount of the DLC film, that is, the DLC film having high wear resistance can be obtained. That is, it was confirmed that the hardness and the wear resistance of the DLC film were changed by the bias voltage Vb. Although illustration is omitted, when the coefficient of friction of the DLC film was evaluated, it was confirmed that the coefficient of friction was not changed by the bias voltage Vb. It was confirmed that the friction coefficient of this DLC film is approximately 0.13 to 0.15, that is, a DLC film having high lubricity can be obtained.

  Furthermore, after a plurality of workpieces 100 of the same disk as described above were attached to the above-mentioned jig along the length direction, a series of surface treatments were performed in the same manner as in the above-described tribology evaluation . Then, with respect to the DLC film generated by this surface treatment, the film thickness distribution of the DLC film in the length direction of the jig, that is, the vertical direction was measured. The results are shown in FIG. The bias voltage Vb in the film forming process for generating the final DLC film is -600V. Moreover, the horizontal axis in FIG. 12 shows the distance to the orthogonal | vertical direction on the basis of the holding | maintenance part of the holder 34 similarly to the above-mentioned FIG. The vertical axis in FIG. 12 represents the film thickness normalized with the film thickness of the thickest portion of the DLC film as one. Further, FIG. 12 also shows the film thickness distribution of the DLC film generated by the above-mentioned prior art for comparison.

  As shown in FIG. 12, according to the present embodiment, in the range from the position of the holder of holder 34 to the position of 400 mm described with reference to FIG. It is confirmed that the value is well within ± 15%. It can be seen that this film thickness distribution is more uniform than the film thickness distribution in the prior art.

  As described above, according to the present embodiment, it is possible to generate a DLC film having a uniform film thickness distribution. Of course, not only the DLC film, but also when forming another film, uniform film thickness distribution can be obtained. Further, not only the film forming process, but also a surface process other than the film forming process such as a nitriding process, uniform treatment can be performed.

  Furthermore, according to the present embodiment, there are the following advantages as compared with the prior art.

For example, in the prior art, in order to increase the number of objects stored in the vacuum chamber, it is necessary to increase the diameter of the revolution path of the objects. In this case, it is necessary to increase the diameter (inner diameter) of the vacuum chamber. Further, along with this, the distance between the plasma and the object to be treated is increased, so the density of the plasma needs to be increased, that is, the output of the plasma gun needs to be increased. In particular, since the current density of ions incident on the object from the plasma is inversely proportional to the square of the distance between the plasma and the object, for example, when the distance is doubled, the output of the plasma gun is It needs to be increased by 4 (= 2 ² ) times. On the other hand, since the output of the plasma gun is limited, the distance between the plasma and the object can not be increased so much, that is, the number of objects contained in the vacuum chamber can not be increased so much. Can not. Separately from this, the height dimension in the vacuum chamber is increased to form a plurality of revolution paths of the object in the height direction (in other words, a plurality of objects are arranged along the height direction) Although the structure can be considered, in this case, in order to make the density of plasma in the height direction uniform, it is necessary to increase the diameter of the pair of electromagnetic coils provided above and below the vacuum chamber. However, this pair of electromagnetic coils is the most expensive of the components of the plasma surface treatment apparatus, and the cost thereof increases significantly as the diameter increases. Therefore, it is not realistic to increase the number of objects stored in the vacuum chamber by this alternative structure. That is, it is unreasonable to increase the number of objects to be processed contained in the vacuum chamber by the extension line of the prior art. This is because, in the prior art, the workpiece revolves around the plasma while rotating.

  On the other hand, in the present embodiment, in order to increase the number of the objects to be treated 100 stored in the vacuum chamber 12, for example, the diameter of the revolution path of the object to be treated 100 may be increased. The diameter (inner diameter) of can be increased. By doing so, according to the present embodiment, it is possible to increase the number of objects 100 to be accommodated in the vacuum chamber 12, that is, more objects 100 can be processed at one time. It can cope with large-scale mass production. According to this embodiment, such a thing can be performed because the to-be-processed object 100 passes while rotating the irradiation area | region of the plasma 300 autorotation.

  Further, according to the present embodiment, it is possible to cope with a large-sized workpiece 100 as shown in FIG. As such a to-be-processed object 100, there exists a rolling roller which has a diameter of 400 mm-600 mm, a height dimension of 300 mm-400 mm, for example. It can be easily understood that the prior art can not cope with such a large object 100 to be treated.

  Further, for example, as shown in FIG. 14, a plurality of, for example, two, plasma guns 16 and 16 may be provided along the outer peripheral direction of the central axis Xa of the vacuum chamber 12. According to this configuration, since the plasmas 300 and 300 are irradiated from the two plasma guns 16 and 16 onto the surface of the object to be treated 100, the surface treatment can be speeded up. In other words, the time required for the surface treatment can be shortened. In FIG. 14, elements unnecessary for the description here, including the detailed configuration of the plasma gun 16, are omitted. The configuration shown in FIG. 14 can also be applied to the case where a plurality of objects to be processed 100, 100,... Are processed at one time as in the configuration shown in FIG. Of course, the number of plasma guns 16 may be three or more.

  For example, as shown in FIG. 15, a plurality of, for example, two plasma guns 16 and 16 may be provided along the extending direction of the central axis Xa of the vacuum chamber 12. According to this configuration, it is possible to cope with a longer object 100 as shown in FIG. In this case, the arrangement, output Wg, etc. of the respective plasma guns 16 and 16 are adjusted such that the plasmas 300, 300,... From the respective plasma guns 16 and 16 do not overlap each other or overlap appropriately. . Also in FIG. 15, as in FIG. 14, elements unnecessary for the description here, including the detailed configuration of the plasma gun 16, are omitted. The configuration shown in FIG. 15 can also be applied to the case where the object 100 with a large diameter as shown in FIGS. 13 and 14, in particular, the longer object 100 is processed. Further, by arranging a plurality of objects to be treated 100 (shorter than those in FIG. 15) as shown in FIG. 1 in the longitudinal direction of central axis Xa of vacuum chamber 12 (in other words, a holder as shown in FIG. By providing a plurality of so-called self-revolution mechanisms including the gear mechanism 36 and the revolving table 38 in the extending direction of the central axis Xa of the vacuum tank 12, a large number of objects 100 can be processed at one time. Of course, also in this case, the number of plasma guns 16 may be three or more.

  The present embodiment is a specific example of the present invention even if it gets tired, and does not limit the scope of the present invention. That is, the present invention may be realized by another form without being limited to the contents described in the present embodiment.

DESCRIPTION OF SYMBOLS 10 plasma surface processing apparatus 12 vacuum chamber 16 plasma gun 34 holder 36 gear mechanism 38 revolving base 40 rotating shaft 42 motor 100 workpiece 300 plasma

Claims (9)

With a vacuum chamber,
Plasma supply means for supplying plasma into the vacuum chamber along a first axis passing through the vacuum chamber;
An object holding and rotating means for rotating an object having a length in the direction of the second axis around the second axis orthogonal to the first axis in the vacuum chamber;
Equipped
The plasma supply means is
A hollow casing disposed outside the vacuum chamber, the inside communicating with the vacuum chamber via a communicating portion, and the first shaft passing through the inside;
An electron emitting electrode which is substantially straight and provided in the housing in parallel with the second axis on the first axis, the electron emitting electrode emitting an electron upon receiving the supply of the electron emitting power;
An electron acceleration is provided between the electron emitting electrode and the communicating portion in the housing, facing the electron emitting electrode at a distance, and is a DC power of positive potential based on the potential of the electron emitting electrode An electron acceleration electrode that receives the supply of power and accelerates the electrons;
A discharge gas supply means for supplying a discharge gas, which is discharged in response to the collision of the accelerated electrons, into the housing;
A magnetic field is generated to apply a magnetic field in a direction along the first axis so that the plasma generated by the discharge of the discharge gas is supplied into the vacuum chamber along the first axis. Means and
Equipped
The electron accelerating electrode has a substantially linear opening, and the opening extends in a direction parallel to the second axis on the first axis and penetrates in the direction along the first axis. ,
The communication portion has a substantially linear opening extending in a direction parallel to the second axis on the first axis,
When the opening of the electron acceleration electrode and the opening of the communication portion are viewed from the distant position on the first axis, the electron acceleration electrode opening and the opening of the communication portion overlap each other. Visible, and the peripheral edge of the opening of the communicating portion is substantially equal to or larger than the opening of the electron accelerating electrode,
The magnetic field generating means generates the magnetic field such that the magnetic field passes between one of the two ends along the second axis at the opening of the electron accelerating electrode and the other. apparatus. The plasma surface treatment apparatus according to claim 1, wherein the magnetic field generation means has a substantially rectangular closed loop electromagnetic coil provided so as to surround the casing . The plasma surface treatment apparatus according to claim 1 or 2, further comprising: bias power supply means for supplying a bias power of a negative potential to the object with reference to the potential of the electron acceleration electrode. apparatus. In the plasma surface treatment apparatus according to any one of claims 1 to 3, the communicating portion wall along said first axis is formed over the entire circumference and plasma surface treatment apparatus of the periphery of the. The plasma surface treatment apparatus according to any one of claims 1 to 4, wherein the object holding and rotating unit holds a plurality of the objects to be processed along a circumferential direction of a circle centered on the second axis. A plasma surface treatment apparatus for further rotating each of the plurality of objects to be processed about a third axis orthogonal to the circumference of a circle and parallel to the second axis . The plasma surface treatment apparatus according to any one of claims 1 to 5, wherein a plurality of the plasma supply means are provided along the outer peripheral direction of the second axis . The plasma surface treatment apparatus according to any one of claims 1 to 6, wherein a plurality of the plasma supply means are provided along the extension direction of the second axis . The plasma surface treatment apparatus according to any one of claims 1 to 7 , wherein an insulating film is formed on the surface of the object using the plasma. 9. The plasma surface treatment apparatus according to claim 8, wherein a material gas as a material of the insulating film is supplied in the vicinity of a supply portion of the plasma from the plasma supply means in the vacuum chamber .

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