JP2005272948A - Plasma enhanced chemical vapor deposition system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma enhanced CVD system which can deal with applications of an in-line type and can satisfactorily treat even a large-sized object to be treated at a low cost. <P>SOLUTION: A coaxial magnetron cathode 34 which is a kind of cold cathode is employed as a means for generating a plasma. As a result, the system can deal with the applications of the in-line type for which the freedom from maintenance is demanded, unlike in the case a hot cathode is used. Also, permanent magnets 36, 36, etc., are built as magnetic field generating means into the coaxial magnetron cathode 36, and thereby the higher density of the plasma is attained. Accordingly, the magnetic field generating means can be made smaller in size and lower in cost as compared to the case the outer side of, for example, a vacuum chamber 12 is provided with an electromagnetic coil as the magnetic field generating means. In addition, the control of the shape of the plasma is facilitated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a plasma CVD (Chemical Vapor Deposition) apparatus, and more particularly, to a plasma CVD suitable for producing a high hardness film such as a DLC (Diamond Like Carbon) film.

  Conventionally, for example, this type of plasma CVD apparatus is disclosed in Patent Document 1. According to this prior art, a plasma chamber for supplying plasma into the vacuum chamber is provided. Specifically, the plasma chamber is provided with a hot cathode, an anode, and an electron injection electrode. The plasma chamber is evacuated together with the inside of the vacuum chamber, and then a discharge gas is introduced into the plasma chamber. In this state, when DC power is supplied to each of the hot cathode, the anode, and the electron injection electrode, the hot cathode is heated and thermoelectrons are emitted from the hot cathode. The emitted thermoelectrons are accelerated toward the anode and collide with molecules of the discharge gas. Due to this collision, molecules of the discharge gas are ionized (dissociated), and plasma is generated. The generated plasma is supplied straight into the vacuum chamber. Note that the plasma chamber is maintained at a constant spatial potential by the above-described electron injection electrode, whereby abnormal discharge in the plasma chamber is suppressed and stable plasma is obtained.

On the other hand, in the vacuum chamber, a first magnetic field and a second magnetic field are applied to control the shape of the plasma. Specifically, the plasma is confined in the vicinity of the center of the vacuum chamber by these magnetic fields, whereby the density of the plasma is increased. A workpiece is disposed around the plasma. In this state, when a material gas is introduced into the vacuum chamber, molecules of the material gas are ionized by plasma. And the ion produced by this ionization collides with the surface of a to-be-processed object, As a result, a film is produced | generated on the surface of the said to-be-processed object. By generating high-density plasma in this manner, the molecules of the material gas can be efficiently ionized, so that a high-hardness film such as a DLC film can be generated. A pair of electromagnetic coils (electromagnets) is presented as a specific example of the first magnetic field generating means and the second magnetic field generating means for generating the first magnetic field and the second magnetic field. In addition, a pulse voltage is applied to the object to be processed in order to increase the collision energy of ions against the surface while preventing charge-up on the surface of the object to be processed.
JP 2000-96250 A

  By the way, the above-mentioned hot cathode is, for example, a tungsten filament having a diameter of about 0.8 [mm] to 1.0 [mm]. This tungsten filament is carbonized and brittle by the material gas in the film formation process, and itself is sputtered, so that its lifetime is short, for example, about 10 to 15 hours. Therefore, in the prior art, it is necessary to frequently replace such a short-lived hot cathode, and there is a problem that much labor and cost are required. In particular, in recent years, it has been desired to realize an in-line type and maintenance-free plasma CVD apparatus in order to cope with mass production. However, in an apparatus having a short-lived hot cathode as in the prior art, the in-line type application is required. Can't cope with it enough.

  Further, the electromagnetic coils constituting the first magnetic field generating means and the second magnetic field generating means are provided outside the vacuum chamber. Therefore, if the vacuum chamber is enlarged, in other words, if a large workpiece can be processed, a correspondingly large electromagnetic coil is required, and the cost of the entire apparatus including the electromagnetic coil increases accordingly. Further, when the electromagnetic coil is increased in size as described above, it becomes difficult to control the magnetic field in the vacuum chamber, and for example, a uniform film thickness distribution cannot be obtained. As a solution for this, for example, the number of electromagnetic coils can be increased. However, when the number of electromagnetic coils is increased in this way, the cost of the apparatus further increases. That is, the prior art cannot cope with in-line applications, and there is a problem that the cost of the apparatus becomes extremely high if a large object to be processed can be processed.

  Accordingly, an object of the present invention is to provide a low-cost plasma CVD apparatus that can sufficiently cope with an in-line type application and that can satisfactorily process a large object to be processed.

  In order to achieve this object, a plasma CVD apparatus according to the present invention is provided in a vacuum chamber in which an object to be processed is stored, a discharge gas introducing means for introducing a discharge gas into the vacuum chamber, and a vacuum chamber. And a discharge electrode for discharging the discharge gas when supplied with the discharge power, and a material gas introduction means for introducing a material gas as a film material into the vacuum chamber. The discharge electrode includes an outer body having a surface facing a portion to be coated of the coating of the object to be processed, and magnetic field generating means built in the outer body so as to generate a magnetic field along the surface. It is.

  That is, in the present invention, the discharge gas is introduced into the vacuum chamber by the discharge gas introduction means. In this state, when discharge power is supplied to the discharge electrode, an electric field is generated on the surface of the discharge electrode, specifically the surface of the outer body, thereby ionizing the molecules of the discharge gas, Plasma is generated. Further, the outer body contains a magnetic field generating means, and the magnetic field generating means generates a magnetic field along the surface of the outer body, in other words, a magnetic field orthogonal to the above-described electric field. Therefore, the plasma is confined in the space along the surface of the outer body by this magnetic field, and as a result, the density of the plasma is increased. When the material gas is introduced into the vacuum chamber by the material gas introduction means, the molecules of the material gas are ionized by the plasma. And the ion of the material gas produced by this ionization collides with the film production | generation object part of a to-be-processed object, and a film is produced | generated by the said film production | generation object part by this.

  Note that the magnetic field generating means preferably includes one or a plurality of permanent magnets. That is, by adopting one or more permanent magnets as the magnetic field generating means, the configuration of the magnetic field generating means can be simplified and the cost can be reduced as compared with the case where, for example, an electromagnet is used. Moreover, the shape of plasma can be controlled more precisely by increasing the number of permanent magnets. This is effective, for example, for performing a uniform film forming process on an object to be processed.

  Moreover, the discharge electrode may be plural. In this way, for example, a film forming process can be effectively performed on a large object to be processed or an object having a complicated structure.

  It is desirable that the discharge power supplied to the discharge electrode is non-DC power. Specifically, pulse power with a frequency of 50 kHz to 250 kHz or high frequency power with a frequency of 13.56 MHz to 26 MHz is used. In particular, the pulse power is preferably asymmetric pulse power.

  Furthermore, you may provide the electric power supply means to supply to-be-processed object power to a to-be-processed object. If it does in this way, the collision energy of the ion with respect to the film production | generation target part of a to-be-processed object can be increased.

  In this case, the workpiece power is preferably non-DC power. Specifically, pulse power with a frequency of 50 kHz to 250 kHz or high frequency power with a frequency of 13.56 MHz to 26 MHz is used. In particular, the pulse power is preferably an asymmetric pulse. By adopting non-direct current power as the object power in this way, for example, when the object to be processed is an insulator, it is possible to prevent charge-up in the film generation target portion of the object to be processed.

  Further, it is desirable that the outer body is formed of a substance having adhesion to the film to be generated. That is, in the film forming process, a film is also formed on the outer body. Here, for example, when the film generated on the outer body is peeled off, the peeled film adheres to the film generation target portion of the object to be processed, and defects such as pinholes and minute protrusions occur in the film generation target portion. there is a possibility. Therefore, if the outer body is formed of a substance having adhesiveness to the coating, it is possible to prevent the coating generated on the outer body from being peeled off. The occurrence of defects can be prevented.

  In addition, when the film to be generated is, for example, a DLC film, it is desirable to use, for example, titanium (Ti) as a substance forming the outer body. That is, since titanium has high adhesion to the DLC film, if the outer body is formed of such titanium, it is possible to prevent the DLC film generated on the outer body from being peeled off. The occurrence of defects can be prevented. In addition to titanium, for example, chromium (Cr) and silicon (Si) also have high adhesion to the DLC film, so that the outer body may be formed of these chromium or silicon.

  According to the present invention, a discharge electrode, which is a kind of cold cathode, is employed as means for generating plasma. Since the cold cathode has a much longer life than the hot cathode, the cold cathode can sufficiently cope with the above-mentioned in-line type application that requires maintenance-free operation. The magnetic field generating means for increasing the density of the plasma is built in the outer body constituting the discharge electrode, that is, provided in the vacuum chamber. Therefore, the magnetic field generating means can be reduced in size as compared with the above-described conventional technique in which the electromagnetic coil is provided outside the vacuum chamber, and accordingly, the cost of the entire apparatus including the magnetic field generating means is reduced. Can do. In addition, the magnetic field in the vacuum chamber can be easily controlled. That is, according to the present invention, it is possible to realize a plasma CVD apparatus that can sufficiently cope with an in-line type application and that can satisfactorily process a large object to be processed at low cost.

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

  As shown in FIG. 1, the plasma CVD apparatus 10 of this embodiment includes a vacuum chamber 12. The vacuum chamber 12 is made of stainless steel (SUS304) formed into a substantially cylindrical shape having a diameter of about 1 [m] and a height of about 0.8 [m], for example. It is connected to a ground potential (GND) as a reference potential. Further, an exhaust port 14 is provided on the side wall (right side in FIG. 1) of the vacuum chamber 12, and a vacuum pump (not shown) serving as an exhaust unit is coupled to the exhaust port 14.

A gas inlet 16 is provided on the upper wall of the vacuum chamber 12, and four gas pipes 18, 20, 22, and 24 are coupled in parallel to the gas inlet 16. One of these, for example, the gas tube 18 functions as a discharge gas introduction means. Specifically, argon (Ar) gas as a discharge gas is introduced into the vacuum chamber 12 through the gas tube 18. Is done. The gas pipe 18 is provided with discharge gas flow rate adjusting means for adjusting the flow rate of argon gas, for example, a mass flow controller 26. The gas pipe 20 is for introducing hydrogen (H ₂ ) gas for ion bombardment, which will be described later, into the vacuum chamber 12. The gas pipe 20 is also provided with a mass flow controller 28 as a gas flow rate adjusting means. It has been. The gas pipe 22 functions as a first material gas introduction means, and specifically, TMS (Tetramethyl silane) as a first material gas is introduced into the vacuum chamber 12 via the gas pipe 22. Gas is introduced. The gas pipe 22 is also provided with a mass flow controller 30 as first material gas flow rate adjusting means. The gas pipe 24 is for introducing acetylene (C ₂ H ₂ ) gas as the second material gas into the vacuum chamber 12. The gas pipe 24 also has a second material gas flow rate. A mass flow controller 32 as adjustment means is provided.

  Furthermore, a cylindrical coaxial magnetron cathode 34 as a discharge electrode is provided at a substantially center of the vacuum chamber 12 so as to extend in the vertical direction. The coaxial magnetron cathode 34 incorporates a plurality of, for example, six permanent magnets 36, 36,..., Specifically, configured as shown in FIG.

  That is, the coaxial magnetron cathode 34 has a housing 340 made of stainless steel (SUS304) as an outer body. The housing 340 includes an upper cylindrical portion 342 and a lower cylindrical portion 344, and the upper cylindrical portion 342 and the lower cylindrical portion 344 coincide with each other with their respective central axes (axes indicated by a one-dot chain line in FIG. 2). It is combined in the state of letting. The inner and outer diameters of the upper cylindrical portion 342 are larger than that of the lower cylindrical portion 344, and the hollow portions 346 and 348 communicate with each other. .. Are housed in the hollow portion 346 of the upper cylindrical portion 342. The permanent magnets 36, 36,.

  These permanent magnets 36, 36,... Are generally known ferrite magnets and are generally formed in a donut shape. The permanent magnets 36, 36,... Are arranged in a row along the direction (vertical direction) in which the upper cylindrical portion 342 extends in a state where the respective central axes coincide with the central axis of the upper cylindrical portion 342, that is, in a coaxial state. Is arranged. Further, the permanent magnets 36 and 36 adjacent to each other are arranged so that the same kind of poles face each other, that is, the N poles or the S poles face each other. The inner diameters of the permanent magnets 36, 36,... Are substantially the same as the inner diameter of the lower cylindrical portion 344. Further, between the permanent magnets 36, 36,..., There are provided substantially disc-shaped fixtures 350, 350,... For fixing the permanent magnets 36, 36,. It has been. These fixtures 350, 350,... Also function as magnetic poles. The upper end of the upper cylindrical portion 342 is closed by a substantially disc-shaped lid 352.

  On the other hand, at the lower end of the lower cylindrical portion 344, two through holes 354 and 356 that penetrate outward from the hollow portion 348 of the lower cylindrical portion 344 are provided. Two straight pipes 358 and 360 having different lengths are coupled to the inner openings (the upper openings in FIG. 2) of these through holes 354 and 356. These straight pipes 358 and 360 are straightly extended from the inner openings of the respective through holes 354 and 356 toward the direction in which the lid 352 is located (upward in FIG. 2). The length of the tube 358 is, for example, about several tens [mm] to several tens [mm]. The longer straight pipe 360 has a length that extends to, for example, the vicinity of the inner surface (the lower surface in FIG. 2) of the lid 352. A water supply pump (not shown) for circulating cooling water in the coaxial magnetron cathode 34 (housing 340) is coupled to the outer openings (lower openings in FIG. 2) of the through holes 354 and 356. . That is, in the film forming process described later, the coaxial magnetron cathode 34 is heated to a temperature of several hundred [° C.]. Therefore, in order to cool the coaxial magnetron cathode 34 heated to such a high temperature, cooling water is supplied to one through hole 354 from the water supply pump. The cooling water flows in the order of the straight pipe 358 → the housing 340 (hollow portions 346 and 348) → the straight pipe 360 → the through hole 356 and is discharged from the through hole 356.

  Further, a cylindrical insulating member 362 is provided outside the lower cylindrical portion 344. The insulating member 362 is formed of a heat-resistant hard resin, and the outer diameter thereof is substantially the same as the outer diameter of the upper cylindrical portion 342. A substantially round flange-like flange 364 is provided so as to fit over the entire circumference of the peripheral wall of the insulating member 362 on the lower side of the peripheral wall. The flange 364 is also made of stainless steel (SUS304) similar to the case 340. However, the flange 364 and the housing 340 are insulated from each other by the insulating member 362.

  Although not shown in detail in the figure (particularly FIG. 1), the coaxial magnetron cathode 34 is fixed to the bottom wall of the vacuum chamber 10. That is, a circular through hole (not shown) that is slightly larger than the outer diameter of the casing 340 (upper cylindrical portion 344) of the coaxial magnetron cathode 34 is provided in the central portion of the bottom wall of the vacuum chamber 10. In the coaxial magnetron cathode 34, a portion from the upper surface (upper surface in FIG. 2) of the flange 364 to the lid 352 is inserted into the through-hole and positioned in the vacuum chamber 12, and the remaining portion (flange 364 in FIG. 2). In a state where the lower part from the lower surface of the vacuum chamber 12 is exposed to the outside of the vacuum chamber 12, it is fixed to the bottom wall of the vacuum chamber 10 by, for example, a bolt (not shown). The total length (height dimension) of the coaxial magnetron cathode 34 is about 500 [mm], for example, and the dimension occupied by the upper cylindrical portion 342 is about 250 [mm]. The outer diameter of the upper cylindrical portion 342 is about 100 [mm], and the thickness of the upper cylindrical portion 342 is about 6 [mm].

  The coaxial magnetron cathode 36 having such a configuration is supplied with high-frequency power Ec as discharge power from a high-frequency power supply device 38 provided outside the vacuum chamber 10. Specifically, the high frequency power Ec is supplied to the housing 340. The high-frequency power Ec is, for example, so-called HF band AC power having a frequency of 13.56 [MHz] to 26 [MHz], and the frequency is within the same range (13.56 [MHz] to 26 [MHz]. (In). Also, the magnitude (power) of the high-frequency power Ec can be arbitrarily adjusted within a range of, for example, 0 [W] to 1200 [W].

  A plurality of, for example, several to dozens of workpieces 40, 40,... Are arranged so as to surround the side surface of the coaxial magnetron cathode 36. Specifically, each of the workpieces 40, 40,... Has a predetermined distance D from the side surface of the coaxial magnetron cathode 36 and the respective film formation target surfaces are opposed to the side surfaces of the coaxial magnetron cathode 36. Placed in a state. In addition, the side surface of the coaxial magnetron cathode 36 mentioned here means the outer peripheral wall surface of the upper cylindrical portion 342 described above. The distance D is about 200 [mm], for example.

  These workpieces 40, 40,... Are individually supported by holders 42, 42,... As support means, and these holders 42, 42,. The rotary table 46 is coupled to the rotary table 46 via the rotary table 46. One end of a rotary shaft 48 is coupled to the central portion of the rotary table 46, and the other end of the rotary shaft 48 is connected to a shaft 52 of a motor 50 as a driving means provided outside the vacuum chamber 12. Are combined. That is, when the motor 50 is driven and the rotating shaft 48 rotates in the direction indicated by the arrow 54 in FIG. 1, the rotary table 46 also rotates in the same direction. As a result, the workpieces 40, 40,... Rotate around the coaxial magnetron cathode 34, so to speak, revolve. Although this revolution speed can be adjusted arbitrarily, it is about 1 [rpm]. Further, due to the rotation transmission action by the gear mechanisms 44, 44,..., The workpieces 40, 40,... Rotate in the directions indicated by arrows 56, 56,. Rotate so to speak. The rotation speed is determined by the revolution speed, and is, for example, about 20 times the revolution speed. Therefore, for example, when the revolution speed is 1 [rpm], the rotation speed is approximately 20 [rpm].

  Further, each of the workpieces 40, 40,... Is supplied with a rotating shaft 48, a rotating table 46, gear mechanisms 44, 44,... From a pulse power supply device 58 as a power supply means provided outside the vacuum chamber 12. A bias voltage Eb as the workpiece power is applied through the holders 42, 42,. The bias voltage Eb is an asymmetric pulse voltage as shown in FIG. 3, and the frequency thereof can be arbitrarily adjusted within a range of 50 [kHz] to 250 [kHz]. Further, the duty ratio of the bias voltage Eb, specifically, the ratio R (= Tb / Ta) of the pulse width (high level period) Tb to one period Ta is, for example, 1 [%] to 40 [%]. It can be arbitrarily adjusted within the range. The high-level voltage value Va can also be arbitrarily adjusted within a range of, for example, 0 [V] to +50 [V] with respect to the installation potential. Further, the low-level voltage value Vb can be arbitrarily adjusted within a range of, for example, 0 [V] to −2000 [V] with respect to the installation potential. In this embodiment, the magnitude of the bias voltage Eb is represented by a DC voltage value, that is, an average value Vdc as shown by a dotted line in FIG. Needless to say, the average value Vdc varies depending on the duty ratio R, the high-level voltage value Va, and the low-level voltage value Vb. However, in this embodiment, the high-level voltage value Va is, for example, +50 [V] constant, The average value Vdc is adjusted by the ratio R and the low-level voltage value Vb.

  Further, a sputter cathode 60 is disposed in the vicinity of the side wall of the vacuum chamber 12, for example, at a position opposite to the side where the exhaust port 14 is provided. The sputter cathode 60 is used in a sputtering process to be described later. A flat target material 62 serving as a film material in the sputtering process, and a magnet 64 disposed along the back surface of the target material 62, have. Note that the target material 62 is arranged with the surface thereof straight toward the side surface of the coaxial magnetron cathode 34, and the magnet 64 is formed to generate a magnetic field along the surface of the target material 62. . The target material 62 is supplied with DC power Es having a negative voltage from a DC power supply device 66 provided outside the vacuum chamber 12. The magnitude of the DC power Es can also be arbitrarily adjusted.

  Now, according to the plasma CVD apparatus 10 configured as described above, it is extremely effective in generating a high hardness film such as a DLC film.

  That is, it is assumed that a plurality of workpieces 40, 40,... Are installed in the vacuum chamber 12 as shown in FIG. In addition, the said to-be-processed object 40,40, ... is a plate-shaped object made from stainless steel (SUS304) whose width dimension is 90 [mm], height dimension is 200 [mm], and thickness is 1 [mm], for example. It is assumed that the respective surfaces (one main surface) are arranged in a state in which they are directed straight to the side surface of the coaxial magnetron cathode 34. It is assumed that the motor 50 is in a stopped state, that is, the workpieces 40, 40,... Are neither revolving nor rotating. Further, it is assumed that all the mass flow controllers 26, 28, 30 and 32 are in a closed state, and that the high frequency power supply device 38, the pulse power supply device 58 and the DC power supply device 66 are all in an OFF (power supply OFF) state.

In this state, first, the inside of the vacuum chamber 12 is evacuated to about 1 × 10 ⁻³ [Pa] by a vacuum pump. After the exhaust, the argon gas is introduced into the vacuum chamber 12 from the gas pipe 18 through the gas inlet 16 at a flow rate of 20 [SCCM] under the control of the mass flow controller 26. At this time, the inside of the vacuum chamber 12 is continuously evacuated by the vacuum pump so that the pressure in the vacuum chamber 12 is maintained within the range of 0.2 [Pa] to 0.8 [Pa]. Then, the high frequency power supply 38 is turned on (power ON), and the high frequency power Ec having a frequency of, for example, 13.56 MHz is supplied from the high frequency power supply 38 to the coaxial magnetron cathode 34 with a magnitude of 1000 [W].

  By supplying the high-frequency power Ec, an electric field is generated on the surface of the coaxial magnetron cathode 34 (the upper cylindrical portion 342 of the housing 340), whereby the argon gas molecules are ionized to generate plasma. Here, on the surface of the coaxial magnetron cathode 34, six permanent magnets 36, 36,. Has occurred. In other words, the magnetic field 68, 68,... Is generated on the surface of the coaxial magnetron cathode 34 in a direction along the surface, in other words, the magnetic field 68, 68,. It has occurred. Therefore, γ electrons (secondary electrons) generated by ionization are confined in the vicinity of the surface of the coaxial magnetron cathode 34 by these magnetic fields 68, 68,. Further, since the γ electrons spirally move around the magnetic fields 68, 68,..., The probability of collision between the γ electrons and the argon gas molecules increases, thereby increasing the plasma density. The strength (magnetic flux density) of the magnetic fields 68, 68,... Is about 0.05 [T] (= 500 [G]) in the vicinity of the surface of the coaxial magnetron cathode 34. At this time, the coaxial magnetron cathode 34 is heated to several hundred [° C.], but is cooled by the above-described cooling water.

  FIG. 4A and FIG. 4B (reference views (a) and (b)) show photographs (images) obtained by actually photographing the state where the plasma is generated. In each of FIG. 4A and FIG. 4B, the cylindrical magnetron cathode 34 that is visible at the approximate center is the coaxial magnetron cathode 34. Six annular white portions surrounding the periphery of the coaxial magnetron cathode 34 are high-density plasma. In such a situation where high-density plasma is generated, the molecules of the material gas introduced into the vacuum chamber 12 can be efficiently ionized during the film formation process, so that a high-hardness film such as a DLC film can be formed. Generation is possible.

  Further, as is apparent from FIGS. 4A and 4B, the plasma is generated along the extending direction of the coaxial magnetron cathode 34. Therefore, a uniform film forming process can be performed on the surface of each workpiece 40 in the extending direction of the coaxial magnetron cathode 34. Further, the coaxial magnetron cathode 34 is a kind of cold cathode, not a hot cathode such as the tungsten filament in the prior art described above. Moreover, the wall thickness (of the upper cylindrical portion 342) is larger than the diameter of the tungsten filament. Therefore, the coaxial magnetron cathode 34 has extremely high corrosion resistance and therefore has a much longer life than the hot cathode in the prior art.

  Next, in the state where the plasma is generated as described above, the pulse power supply device 58 is turned ON, and the frequency of the processing object 40, 40,. Thus, a bias voltage Eb having a duty ratio R of 30 [%] and an average voltage value Vdc of −100 [V] is applied. As a result, the argon ions in the plasma are accelerated toward the surface of each workpiece 40, 40,..., And are incident on the surface of each workpiece 40, 40,. Here, the magnitude of the 13.56 MHz high frequency power Ec supplied to the coaxial magnetron cathode 34 is changed stepwise within a range of 50 [W] to 1000 [W] by operating the high frequency power supply device 38. . And the electric current Ib which flows into each to-be-processed object 40,40, ... from the pulse power supply 58 at this time was measured. The result is shown by a solid curve 100 in FIG.

  As is apparent from the curve 100, when the high-frequency power Ec increases, the current Ib flowing through the workpieces 40, 40,. Here, the current Ib indicates the amount of argon ions incident on the surfaces of the workpieces 40, 40,..., In other words, the plasma density. That is, when the high frequency power Ec is increased, the plasma density is increased, and when the high frequency power Ec is decreased, the plasma density is decreased. This shows that the plasma density can be controlled by the high frequency power Ec.

  Further, in the state where plasma is generated as described above, the mass flow controller 32 is controlled to introduce acetylene gas into the vacuum chamber 12 from the gas pipe 24 through the gas inlet 16 at a flow rate of 100 [SCCM]. Let That is, the same environment as that of the DLC film generation process described later is formed. And the magnitude | size of the high frequency electric power Ec was changed in steps within the range of 50 [W]-1000 [W], and current Ib at this time was measured. The result is shown by a dotted curve 102 in FIG.

  As is apparent from the curve 102, even in the same environment as the DLC film generation process, when the high-frequency power Ec increases, the current Ib flowing through the workpieces 40, 40,. To do. That is, it can be seen that the plasma density can be controlled by the high-frequency power Ec, and the amount of acetylene ions incident on the surfaces of the workpieces 40, 40,.

  Subsequently, in the same environment as the DLC film generation process as described above, the magnitude of the high-frequency power Ec is kept constant at 400 [W], and in this state, the voltage value of the bias voltage Eb is set to 0 [V] to -1200 [ V], and the current Ib at this time was measured. The result is shown by a solid curve 110 in FIG. Similarly, the magnitude of the high-frequency power Ec is constant at 1000 [W], and in this state, the voltage value of the bias voltage Eb changes stepwise within the range of 0 [V] to -1200 [V]. The current Ib at this time was measured. The result is shown by a dotted curve 112 in FIG.

  As is clear from these curves 110 and 112, the larger the high-frequency power Ec, the larger the current Ib, that is, a high-density plasma is obtained. This is the same as the relationship shown in FIG. Then, regardless of whether the magnitude of the high-frequency power Ec is 400 [W] or 1000 [W], the current Ib is almost saturated in the range where the absolute value of the bias voltage Eb exceeds 50 [V]. Here, the voltage value of the bias voltage Eb means the incident energy (impact force) of ions with respect to the surface of the workpieces 40, 40,. Specifically, the incident energy increases as the absolute value of the bias voltage Eb increases, and the incident energy decreases as the absolute value of the bias voltage Eb decreases. That is, the incident energy of ions can be controlled by the bias voltage Eb.

  As described above, according to this embodiment, the plasma density can be controlled by the high frequency power Ec supplied to the coaxial magnetron cathode 34, and the amount of ions incident on the workpieces 40, 40,. Can be controlled. And the incident energy of the ion with respect to the surface of each said to-be-processed object 40,40, ... can be controlled with the bias voltage Eb applied to each to-be-processed object 40,40, .... That is, the amount of ions and the incident energy of the ions can be individually controlled. This is extremely important for successfully producing various coatings including a DLC film.

  Therefore, in order to verify what kind of DLC film can be generated by this embodiment, the following experiment was performed. That is, as the workpieces 40, 40,..., High-speed tool steel, high-speed (SKH4A) steel, is installed. Specifically, a square pillar high-speed steel having a side of 8 [mm] and a length of 30 [mm] is fixed to the surface of the plate-like body described above so that its longitudinal direction extends in the vertical direction. (That is, the plate-like body is used as an attachment jig). Then, as shown in FIG. 7, a titanium film 70, a silicon-containing DLC film 72, and a DLC film 74 are formed in this order on the surface of the high-speed steel. The reason why the silicon-containing DLC film 72 is provided under the DLC film 74 is to relieve internal stress of the DLC film 74. The reason why the titanium film 70 is provided under the silicon-containing DLC film 72 is to improve the adhesion of the silicon-containing DLC 72 to the surface of the workpiece 40. Before entering this experiment, each of the mass flow controllers 26, 28, 30 and 32 is in a closed state, and the high frequency power supply device 38, the pulse power supply device 58 and the DC power supply device 66 are all OFF. Suppose you are in a state. The motor 50 is assumed to be stopped.

In this state, first, the inside of the vacuum chamber 12 is evacuated to about 1 × 10 ⁻³ [Pa] by a vacuum pump. Then, after this exhaust, the motor 50 is driven to revolve the workpieces 40, 40,... At 1 [rpm]. By this revolution, each of the workpieces 40, 40,... Rotates at 20 [rpm]. Then, argon gas is introduced into the vacuum chamber 12 at a flow rate of 20 [SCCM] by the control of the mass flow controller 26, and hydrogen gas is introduced into the vacuum chamber 12 at a flow rate of 100 [SCCM] by the control of the mass flow controller 28. Let it be introduced. At this time, the vacuum chamber 12 is continuously evacuated by a vacuum pump so that the pressure in the vacuum chamber 12 is maintained at 0.2 [Pa]. Further, the high frequency power supply device 38 is turned on, and the high frequency power Ec of 13.56 MHz is supplied from the high frequency power supply device 38 to the coaxial magnetron cathode 34 in a magnitude of 500 [W]. Then, the pulse power supply device 58 is turned on, the frequency is 100 [kHz], the duty ratio R is 30 [%], and the average voltage value from the pulse power supply device 58 to each workpiece 40, 40,. A bias voltage Eb with Vdc of −600 [V] is applied. Under such circumstances, as described above, each molecule of argon gas and hydrogen gas is ionized, and plasma is generated. The argon ions and hydrogen ions generated by this ionization are accelerated toward the surface of each object to be processed 40, 40,..., And are incident on the surface of each object to be processed 40, 40,. Thereby, the surface of each said processed material 40,40, ... is wash | cleaned, and what is called an ion bombard process is performed. This ion bombardment process is performed for 20 minutes.

  After the ion bombardment process is completed, a titanium film 70 is generated by a sputtering process. That is, the introduction of hydrogen gas is stopped by controlling the mass flow controller 28. Then, the mass flow controller 26 is controlled to increase the flow rate of the argon gas to 80 [SCCM]. At this time, the pressure is adjusted so that the pressure in the vacuum chamber 12 becomes 0.3 [Pa]. Further, the DC power supply device 66 is turned ON, and 1 [kW] of DC power Es is supplied from the DC power supply device 66 to the target material 62. Thereby, argon ions in the plasma collide with the surface of the target material 62, and molecules (or atoms) of the target material 62 are knocked out from the surface. The struck molecules are ionized by the plasma, and the titanium ions generated by this ionization are accelerated toward the surface of each object 40, 40,..., And the surface of each object 40, 40,. Is incident on. Thereby, the titanium film 70 is produced | generated on the surface of each to-be-processed object 40,40, .... This sputtering process is performed for 15 minutes. As a result, the thickness of the titanium film 70 was about 150 [nm].

  After performing the sputtering process, a silicon-containing DLC film 72 is generated. That is, the DC power supply device 66 is turned off. Then, the mass flow controller 26 lowers the flow rate of argon gas to 20 [SCCM], and the mass flow controller 30 introduces TMS gas into the vacuum chamber 12 at a flow rate of 30 [SCCM]. Further, the acetylene gas is introduced into the vacuum chamber 12 by the mass flow controller 32 at a flow rate of 100 [SCCM]. At this time, the pressure in the vacuum chamber 12 is adjusted to 0.4 [Pa]. According to this condition, each molecule of TMS gas and acetylene gas is ionized by plasma, and TMS ions and acetylene ions generated by this ionization are accelerated toward the surfaces of the workpieces 40, 40,. Are incident on the surfaces of the workpieces 40, 40,..., Strictly, the surfaces of the titanium film 70 described above. As a result, a silicon-containing DLC film 72 is generated on the titanium film 70. This treatment is carried out for 5 minutes. As a result, the film thickness of the silicon-containing DLC film 72 was about 100 [nm].

  Next, a DLC film 74 (containing no silicon) is generated. That is, the DC power supply device 66 is turned off. Then, the mass flow controller 30 is controlled to stop the introduction of the TMS gas. That is, only argon gas and acetylene gas are introduced into the vacuum chamber 12. Thereby, each molecule of acetylene gas in the plasma is incident on the surface of each object to be processed 40, 40,..., Strictly, the surface of the silicon-containing DLC film 72. In addition, a DLC film 74 containing no silicon is generated. The generation process of the DLC film 74 is performed for 1 hour. Then, upon completion of the generation process of the DLC film 74, a series of surface treatments on the workpieces 40, 40,.

  In the above-described generation process of the DLC film 74, a pulse voltage having a voltage value Vdc different from that described above was applied as the bias voltage Eb, and the DLC film 74 was generated even under this condition. Specifically, the voltage value Vdc of the bias voltage Eb is set to −50 [V], −100 [V], −200 [V], and −400 [V], and the DLC film 74 is generated under these conditions. . Then, the hardness of the DLC film 74 generated under different conditions was measured, and the film formation rate was calculated from the film thickness. The result is shown in FIG.

  In FIG. 8, a solid curve 120 represents hardness. As can be seen from this curve 120, the greater the voltage value (absolute value) Vb of the bias voltage Eb, the higher the hardness. In particular, by setting the absolute value Vb to 400 [V] or more, a hardness of 2000 [HK] or more can be obtained. This value of 2000 [HK] or higher represents a hardness equal to or higher than that of the DLC film generated by the above-described conventional technology. That is, according to this embodiment, it is possible to generate the DLC film 74 having the same or higher hardness as that generated by the conventional technique.

  In FIG. 8, a dotted curve 122 represents the deposition rate. According to this curve 122, it can be seen that when the voltage value (absolute value) Vb of the bias voltage Eb is large, the film formation rate is lowered. Specifically, when the absolute value Vb is 200 [V] or more, the film formation rate is saturated at about 2.3 [μm / h]. As described above, when the absolute value Vb increases, the incident energy of ions on the surface of the workpieces 40, 40,... Increases, thereby densifying the DLC film 74. As a result, the film formation speed is increased. Is considered to decrease.

Further, the triploidy characteristics of the DLC film 74 were measured. Specifically, when the friction coefficient with respect to the high carbon chromium bearing steel (SUJ2) is measured for the DLC film 74 generated under the condition that the voltage value Vb of the bias voltage Eb is −600 [V], the friction coefficient is It was 0.1 or less. The specific wear amount was 3 × 10 ⁻⁸ [mm ³ / N · m]. These values are values that sufficiently satisfy a value (specification) necessary to be generally called a “DLC film”. That is, according to this embodiment, it was proved that a DLC film 74 having sufficient triploidy characteristics as a “DLC film” can be obtained.

  Further, the thickness distribution of the DLC film 74 was measured. However, in the measurement of the film thickness distribution, silicon substrates were used as the workpieces 40, 40,. Specifically, the above-mentioned plate-like body is formed so that each surface (one main surface) is along a vertical direction with a silicon substrate having a side of 20 [mm] and a thickness of 0.56 [mm]. Fix it side by side on the surface. The silicon substrate is subjected to ion bombardment, sputtering (titanium film 72 generation), silicon-containing DLC film 72 generation, and DLC film 74 generation in this order in the same manner as described above. Apply with. Further, one of the silicon substrates subjected to the series of surface treatments is randomly extracted, and the film thickness of the DLC film 74 at each location on the surface of the extracted silicon substrate is measured. Then, the thickness of the portion where the thickness of the DLC film 74 is the largest is set to 1, and the thickness of the other portion is expressed as a ratio to 1. The result is shown in FIG.

  In FIG. 9, the horizontal axis (X axis) represents each part of the surface of the silicon substrate as a distance from the upper edge of the silicon substrate. The vertical axis (Y axis) represents the film thickness (ratio) in each portion. As can be seen from FIG. 9, the minimum value of the film thickness is about 0.86 with respect to the maximum value of the film thickness. In other words, when the intermediate value of the film thickness in the entire silicon substrate is used as a reference value, the film thickness variation with respect to the reference value is within ± 7 [%]. The value of ± 7 [%] is a value that is sufficiently satisfactory for a sliding part such as an engine cylinder. That is, according to this embodiment, it can be seen that a film thickness distribution with sufficient accuracy as a sliding component can be obtained.

  As described above, according to this embodiment, plasma is generated by the coaxial magnetron cathode 34 which is a kind of cold cathode. The coaxial magnetron cathode 34 has a much longer life than the hot cathode in the prior art described above, and therefore can sufficiently cope with an in-line type application requiring maintenance-free. Further, the coaxial magnetron cathode 34 incorporates permanent magnets 36, 36,... As magnetic field generating means for increasing the density of plasma. Therefore, the magnetic field generating means can be reduced in size and cost compared to the configuration in which the electromagnetic coil as the magnetic field generating means is provided outside the vacuum chamber as in the prior art. In addition, the shape of the plasma can be easily controlled. When these are combined, it is possible to sufficiently deal with in-line applications, and it is possible to exhibit a unique effect that large objects 40, 40,.

  In this embodiment, only one coaxial magnetron cathode 34 is provided, but the present invention is not limited to this. For example, when a large object or a complicated structure is processed as the object to be processed 40, the object to be processed 40 is installed in the approximate center in the vacuum chamber 12, as shown in FIG. A plurality of coaxial magnetron cathodes 34, 34,...

  Further, in the process of generating the silicon-containing DLC film 72 described above, the silicon-containing DLC film is also generated on the side surface of the coaxial magnetron cathode 34, specifically, the side surface of the upper cylindrical portion 342. Here, since the upper cylindrical portion 342 is made of stainless steel as described above, the adhesion with the silicon-containing DLC film is not good. Therefore, in the production process of the silicon-containing DLC film 72, the silicon-containing DLC film produced on the upper cylindrical portion 342 is peeled off and reattached to the surface of the workpieces 40, 40,. There is a possibility that defects such as pinholes and minute protrusions may occur on the surfaces of the objects 40, 40,. Therefore, in order to prevent the occurrence of such a problem, for example, as shown in FIG. 11, a titanium layer 370 having good adhesion to the silicon-containing DLC film may be provided on the side surface of the upper cylindrical portion 342. In this way, in the process of generating the silicon-containing DLC film 72, it is possible to prevent the silicon-containing DLC film generated on the titanium layer 370 from being peeled off, thereby preventing the occurrence of the problem.

  When the titanium layer 370 is thus provided, the titanium layer 370 can be used as a target material in the above-described sputtering process. In this way, by using the titanium layer 370 as a target material, the deposition rate of the titanium film 70 in the sputtering process can be improved. Further, when there is no need to improve the film forming speed, the sputter cathode 60 can be omitted.

  Further, in this embodiment, ferrite magnets are used as the above-described permanent magnets 36, 36,..., But are not limited thereto. For example, you may use other magnets, such as a Sm-Co magnet, a neodymium magnet, and an alnico magnet. However, a strong magnet is used in the vicinity of the surface of the coaxial magnetron cathode 36 so as to obtain a magnetic flux density of at least 0.02 [T] or more, more preferably about 0.05 [T] to 0.1 [T]. There is a need.

  Further, instead of the permanent magnets 36, 36,..., Electromagnetic coils (electromagnets) may be used. However, the use of the permanent magnets 36, 36,... As in this embodiment is more advantageous for simplifying the configuration and reducing the cost than using the electromagnetic coils.

And although TMS gas and acetylene gas were used as material gas, it is not restricted to this. For example, other hydrocarbon gases such as methane (CH ₄ ) gas and ethylene (C ₂ H ₄ ) gas, or gases other than hydrocarbon gases such as silane (SiH ₄ ) gas and boron trichloride (BCl ₃ ). It may be used.

  Furthermore, instead of the titanium film 70 as the so-called intermediate layer in FIG. 7, for example, a chromium film or a silicon film may be generated. That is, since chromium and silicon also have high adhesion to the silicon-containing DLC film 72, the intermediate layer 70 may be generated using these chromium or silicon as a material.

  The high-frequency power Ec is supplied to the coaxial magnetron cathode 36. Alternatively, pulse power having an asymmetric pulse waveform with a frequency of 50 [kHz] to 250 [kHz] may be supplied. However, high-frequency plasma Ec tends to be obtained when high-frequency power Ec is supplied, compared to when asymmetric pulse power is supplied.

  Moreover, although the pulse voltage of the asymmetrical pulse waveform was applied to the workpieces 40, 40,... As the bias voltage Eb, high frequency power having a frequency of 13.56 [MHz] to 26 [MHz] was used instead. You may supply. In particular, when the workpieces 40, 40,... Are insulators, by suppressing the charge-up on the surfaces of the workpieces 40, 40,. A good film forming process can be performed. However, in this case, it is necessary to provide a matching circuit between each of the workpieces 40, 40,... And the high-frequency power supply source in order to match impedance between them.

  In this embodiment, as a specific example, the case where the titanium layer 70, the silicon-containing DLC film 72, and the DLC film 74 as shown in FIG. 7 are generated has been described. Needless to say, the present invention can be applied. Further, the present invention can be applied not only to the film forming process but also to other surface processes such as a nitriding process.

It is a figure which shows schematic structure of one Embodiment of this invention. It is a longitudinal cross-sectional view of the coaxial magnetron cathode in the same embodiment. It is an illustration figure which shows the waveform of the bias voltage applied to a to-be-processed object in the same embodiment. It is an illustration figure which shows the generation state of the plasma by the coaxial magnetron cathode in the same embodiment. It is a graph which shows the relationship between the high frequency electric power supplied to a coaxial magnetron cathode in the same embodiment, and the electric current which flows into a to-be-processed object. 4 is a graph showing a relationship between a bias voltage applied to a workpiece and a current flowing through the workpiece in the embodiment. It is an illustration figure which expands and shows the cross section of the to-be-processed object after giving a series of surface treatments in the same embodiment. It is a graph which shows the experimental result in the same embodiment. It is a graph which shows the experimental result different from FIG. It is a figure which shows another structural example of the embodiment. FIG. 3 is a longitudinal sectional view of a coaxial magnetron cathode having a structure different from that in FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Plasma CVD apparatus 12 Vacuum chamber 16 Gas inlet 18, 20, 22, 24 Gas pipe 26, 28, 30, 32 Mass flow controller 34 Coaxial magnetron cathode 36 Permanent magnet 40 To-be-processed object 340 Housing

Claims (8)

A vacuum chamber in which an object to be processed is stored;
A discharge gas introduction means for introducing a discharge gas into the vacuum chamber;
A discharge electrode that is provided in the vacuum chamber and discharges the discharge gas by being supplied with discharge power; and
A material gas introducing means for introducing a material gas as a material of the coating into the vacuum chamber;
Comprising
The discharge electrode comprises: an outer body having a surface facing the generation target portion of the coating of the object to be processed; and a magnetic field generating means incorporated in the outer body so as to generate a magnetic field along the surface. Prepare
Plasma CVD equipment.   The plasma CVD apparatus according to claim 1, wherein the magnetic field generating means includes at least one permanent magnet.   The plasma CVD apparatus according to claim 1, comprising a plurality of the discharge electrodes.   The plasma CVD apparatus according to any one of claims 1 to 3, wherein the discharge power is pulse power having a frequency of 50 kHz to 250 kHz or high frequency power having a frequency of 13.56 MHz to 26 MHz.   The plasma CVD apparatus according to any one of claims 1 to 4, further comprising power supply means for supplying workpiece power to the workpiece.   6. The plasma CVD apparatus according to claim 5, wherein the power of the object to be processed is pulse power having a frequency of 50 kHz to 250 kHz or high frequency power having a frequency of 13.56 MHz to 26 MHz.   The plasma CVD apparatus according to any one of claims 1 to 6, wherein the outer body is formed of a substance having adhesion to the film. The coating is a DLC film,
The plasma CVD apparatus according to claim 7, wherein the substance is any one of titanium, chromium, and silicon.