JP2006037153A - Film deposition apparatus and film deposition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film deposition apparatus and a film deposition method for generating a practical BN film. <P>SOLUTION: Each work 36 is successively conveyed to a plasma area 68 by a rotating/revolving mechanism 28. In the plasma area 68, a BN film formed of boron stored in a crucible 22 and gaseous nitrogen introduced via a gas pipe 58. At this time, high frequency power Eb with a DC component Vdc superposed thereon is supplied to the work 36 as bias power. When the DC component Vdc is largely fluctuated, breakage or peeling as a result of the BN film can be induced. However, in this film deposition apparatus 10, fluctuation of the DC component Vdc is suppressed by a voltage control circuit 66. Thus, the practical BN film free from peeling can be deposited. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a film forming apparatus and a film forming method, and more particularly to a film forming apparatus and a film forming method for generating a film on the surface of an object to be processed by, for example, an ion plating method.

As a film forming apparatus that employs the ion plating method, there is a conventional one disclosed in Patent Document 1, for example. According to this prior art, it is particularly suitable for producing a cBN (Cubic Boron Nitride) film. Specifically, as disclosed in the paragraph 0039 of Patent Document 1, Prior to the generation of the cBN film, a TiN (titanium nitride) film as an intermediate layer is generated. Then, as disclosed in paragraph 0040 of Patent Document 1, in order to improve the adhesion between the TiN film and the cBN film, a B (boron) film is generated, and further a BN (boron nitride) film. Is generated. In the process of forming the BN film, the flow rate ratio of nitrogen (N ₂ ) gas as a material gas to argon (Ar) gas as a discharge gas is increased step by step, whereby the composition ratio of nitrogen to boron ( N / B ratio) increases stepwise, and finally a cBN film is produced. At this time, a high frequency (RF) power as a bias power is supplied to the substrate as the object to be processed in order to promote the collision of ions with the surface of the substrate. The power value of the high-frequency power is also increased stepwise, thereby improving the adhesion of the BN film including the cBN film and realizing the generation of the cBN film.
JP 2002-105624 A

  However, the BN film including the above-described cBN film generally has a property of being easily peeled off. This property becomes more remarkable as the composition ratio is larger, in other words, as a harder BN film is generated. This is no exception for the cBN film produced by the above-described prior art. For this reason, in the prior art, as disclosed in the paragraph 0041, a TiN film as a protective film is formed on the cBN film. Thus, when the cBN film is covered with another film, the characteristics of the bent cBN film (characteristics such as high hardness, low friction coefficient and high heat resistance) are not exhibited, and there is no possibility of forming this cBN film. Makes sense. In other words, a conventional cBN film could not be generated with the prior art.

  Therefore, the cause (mechanism) of peeling of a particularly hard BN film including the cBN film has been investigated, and it has been found that the high-frequency power supplied to the substrate has a great influence. That is, a direct current component is superimposed on the high frequency power, and when the power value of the high frequency power is changed stepwise as described above, the direct current component also fluctuates accordingly. Then, it has been found that when the fluctuation amount of the direct current component is large, a large electric field fluctuation occurs in the BN film, which causes the BN film to be partially broken and eventually peeled off.

  Based on such research results, an object of the present invention is to provide a film forming apparatus and a film forming method capable of generating a practical film that does not cause peeling of an insulating film such as a hard BN film. .

  In order to achieve this object, the first invention is a film forming apparatus that generates a film on the surface of an object to be processed by an ion plating method, and supplies an AC bias power with a DC component superimposed on the object to be processed. And a control means for controlling the direct current component.

  That is, in the first invention, a film is generated on the surface of the object to be processed by the ion plating method. At this time, AC bias power on which a DC component is superimposed is supplied from the bias supply means to the object to be processed in order to promote ion collision with the surface of the object to be processed. The direct current component is controlled by the control means.

  As described above, in the formation of a compound film such as a BN film, the composition ratio of the film material may be gradually changed in order to improve the adhesion of the film. In such a case, it is desirable that the control means gradually increase the direct current component in accordance with the change in the composition ratio.

  Further, in this case, it is desirable to suppress the increase amount of the DC component per minute to 5 V or less. In this way, it was confirmed that by suppressing the increase degree (speed) of the direct current component, it is possible to prevent the coating from being destroyed and eventually peeled off.

  The coating referred to here may be an insulating coating such as a BN film.

  However, in the process of generating the insulating film, charges due to ion irradiation are accumulated on the upper surface of the insulating film sequentially generated on the surface of the object to be processed. Then, electrons are procured from the discharge space (plasma region) so as to cancel out this electric charge, whereby electrons become insufficient in the discharge space and the plasma becomes unstable. Therefore, in order to compensate for the shortage of electrons, an electron supply means for additionally supplying electrons to the discharge space may be further provided. In this way, the plasma can be stabilized.

  According to a second aspect of the present invention, there is provided a film forming method for forming a film on a surface of an object to be processed by an ion plating method, a bias supply process for supplying an AC bias power having a DC component superimposed on the object to be processed, and the direct current And a control process for controlling the components.

  That is, the second invention is a method invention corresponding to the first invention, and thus has the same effect as the first invention.

  According to the present invention, since the direct current component of the bias power supplied to the object to be processed is controlled, the fluctuation of the direct current component that greatly affects the destruction of the film is suppressed. Therefore, unlike the above-described conventional technique in which not the DC component but the bias power (power value) itself is controlled, even when an insulating coating such as a hard BN film is generated, the coating is broken and thus peeled off. And can produce a practical coating.

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

  The film forming apparatus 10 according to this embodiment employs an ion plating method, and has a substantially cylindrical vacuum chamber 12 as shown in FIGS. 1 is a view of the inside of the film forming apparatus 10 as viewed from the front, FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line BB in FIG. It is.

  The vacuum chamber 12 is arranged in a state where the portions corresponding to both ends of the cylindrical shape are oriented in the horizontal direction, and the portions corresponding to the both ends are a substantially disk-shaped front wall plate 14 and a rear substantially the same shape as this. It is closed by a wall plate 16. The vacuum chamber 12 including the front wall plate 14 and the rear wall plate 16 is made of, for example, stainless steel (SUS304), and is itself connected to a ground potential (GND) as a common potential. The inside of the vacuum chamber 12 is evacuated by a vacuum pump (not shown) serving as an evacuation unit. In addition, the diameter C of the vacuum chamber 12 is 1140 mm, for example, and the depth D is 885 mm, for example.

  An evaporation source 18 is disposed at the approximate center in the vacuum chamber 12. The evaporation source 18 includes a crucible 22 in which the evaporation material 20 is accommodated, and material heating means for heating the evaporation material 20, for example, an electron gun 24. Further, a heater 26 as a tank heating means is disposed in the vicinity of the lower part of the evaporation source 18. Although not shown in the drawing, the electron gun 24 emits an electron beam by being supplied with a predetermined DC power (electron gun power) from an electron gun power supply device provided outside the vacuum chamber 12. The evaporation material 20 is heated. The heater 26 is heated by supplying predetermined AC power from a heater power supply device provided outside the vacuum chamber 12.

  A self-revolving mechanism 28 is provided in the vacuum chamber 12. Specifically, the self-revolving mechanism 28 has a disk-shaped housing whose diameter is slightly smaller than the diameter C (strictly, inner diameter) of the vacuum chamber 12, for example, about 100 mm, and the center of this housing is It is provided close to the inner surface of the rear wall plate 16 in a state where it coincides with the central axis of the vacuum chamber 12 (cylindrical). A rotation shaft 30 is provided at the center of the self-revolution mechanism 28, and the rotation shaft 30 penetrates the rear wall plate 16 and is not shown in the figure of a motor 32 provided outside the vacuum chamber 12. Connected to the shaft. Further, a plurality of, for example, 72 holders 34, 34,... As support means are provided in the vicinity of the front peripheral edge of the self-revolving mechanism 28 along the peripheral edge at equal intervals. And the to-be-processed object 36 is attached to each of these holders 34, 34, .... Here, as the workpiece 36, for example, a drill (blade) having a diameter of about 10 mm which is made of high-speed steel (SKH51) is used. The workpiece 36 is attached to each holder 34 so as to extend in a direction along the central axis of the vacuum chamber 12. The diameter of a circle drawn by the arrangement of the holders 34, 34,... (The distance between the two holders 34 and 34 facing each other across the central axis of the vacuum chamber 12) F is, for example, 920 mm. Yes. The protrusion dimension G of the workpiece 36 including the holder 34 is, for example, 300 mm.

  According to the self-revolving mechanism 28, when the motor 32 is driven and the rotary shaft 30 rotates, the workpieces 36, 36,... Attached to the holders 34, 34,. , For example, in the direction indicated by the arrow 38 in FIG. 1 (clockwise). In other words, the workpieces 36, 36,... Revolve around the evaporation source 14. At the same time, each of the objects to be processed 36, 36,... Rotates, for example, clockwise around itself, and so on. Note that the rotation speed is faster than the revolution speed, for example, 10 times the revolution speed.

  Furthermore, a cathode 40 and an anode 42 are provided in the vacuum chamber 12 so as to face each other at a distance. Among these, the cathode 40 is, for example, a substantially linear filament made of tungsten having a diameter of about 1 mm and a length of about 200 mm to 400 mm (strictly, a plurality of (for example, three) filaments arranged in a substantially linear form). It has. The cathode 40 is substantially in the middle between the evaporation source 18 and the workpiece 32 directly above the cathode 40 and when viewed from the front of the vacuum chamber 12 (in FIG. 1) than the center of the vacuum chamber 12. It is arranged at a position slightly to the right so as to extend in a direction along the central axis of the vacuum chamber 12.

  On the other hand, the anode 42 is made of, for example, molybdenum steel or tungsten steel, and is formed in a rectangular column shape having a length dimension of about 200 mm to 400 mm. The anode 42 is disposed so as to extend in a direction along the central axis of the vacuum chamber 12 at a position substantially opposite to the cathode 40 across a vertical plane passing through the central axis of the vacuum chamber 12. Yes. The distance between the anode 42 and the cathode 40 is, for example, about 200 mm to 300 mm.

  The cathode 40 is supplied with AC cathode power Ec from a cathode heating power supply device 44 as cathode power supply means provided outside the vacuum chamber 12. A DC cathode bias voltage Vcb is applied to the ground terminal of the cathode heating power supply 44 from a cathode bias power supply 46 as a cathode bias supply means. That is, the DC cathode bias voltage Vcb is superimposed on the AC cathode power Ec. The cathode bias voltage Vcb is a negative voltage with respect to the ground potential.

  On the other hand, a DC anode voltage Va is applied to the anode 42 from an anode power supply device 48 as an anode power supply means provided outside the vacuum chamber 12. The anode voltage Va is a positive voltage based on the ground potential.

  Further, the vacuum chamber 12 is provided with a pair of magnetic field generators 50 and 52 as magnetic field generating means with the cathode 40 and the anode 42 interposed therebetween. Specifically, each of the magnetic field generators 50 and 52 has an elongated rectangular parallelepiped housing. The magnetic field generators 50 and 52 are arranged such that one side faces each other with the cathode 40 and the anode 42 sandwiched therebetween, strictly speaking, the one side faces obliquely upward, and the cathode 40 and the anode It is arranged so as to extend in parallel with 42 (that is, to extend in a direction along the central axis of the vacuum chamber 12). In addition, the length dimension of each magnetic field generator 50 and 52 is about 200 mm-400 mm, for example. Moreover, the distance between each magnetic field generator 50 and 52 is about 250 mm-350 mm, for example.

  Each of the magnetic field generators 50 and 52 includes a permanent magnet (not shown). Specifically, the permanent magnet is incorporated so that one side surface (in other words, the inner side surface) of each of the magnetic field generators 50 and 52 facing each other becomes a different magnetic pole. Here, the inner surface of the magnetic field generator 50 disposed on the cathode 40 side is the S pole, and the inner surface of the magnetic field generator 52 disposed on the anode 42 side is the N pole. As a result, a magnetic field is generated in a space between these magnetic field generators 50 and 52.

  Furthermore, yokes 54 and 56 are attached to the magnetic field generators 50 and 52 in order to expand the magnetic field generation region. These yokes 54 and 56 are plate-shaped, and the width dimension is larger than the width dimension of each magnetic field generator 50 and 52 (housing | casing), for example, each said magnetic field generator 50 and 52 (housing | housing). ) Width dimension of about 1.5 to 2 times. The length dimensions of the yokes 54 and 56 are substantially the same as the length dimensions of the magnetic field generators 50 and 52. These yokes 54 and 56 cover the surface opposite to the inner surface of each of the magnetic field generators 50 and 52 (in other words, the outer surface), and protrude upward from the upper edge of the outer surface. Is attached. By attaching the yokes 54 and 56, the magnetic field generation region by the magnetic field generators 50 and 52 is further expanded.

  As described above, each of the magnetic field generators 50 and 52 is arranged with one side facing each other obliquely upward. This is also for expanding the magnetic field generation region. This is because a wide magnetic field is formed in the vicinity of the workpieces 36, 36,... While maintaining a constant magnetic flux density. The inclination angles of the magnetic field generators 50 and 52 vary depending on the distance between them, for example, 5 to 45 degrees, and here, about 30 degrees. Needless to say, the yokes 54 and 56 are inclined according to the inclination of the magnetic field generators 50 and 52. Similarly, the anode 42 is also tilted in the same direction as the magnetic field generator 52 disposed on the anode 42 side. With this configuration, in this embodiment, a magnetic flux density of, for example, 6 mT to 10 mT is obtained in the approximate center between the magnetic field generators 50 and 52. In addition, the height H from the upper edge of each magnetic field generator 50 and 52 to the workpiece 36 at the uppermost position (the uppermost position of the revolution track) is, for example, 105 mm ± 60 mm.

  A reactive gas is introduced into the vacuum chamber 12 through a gas pipe 58 as a gas introduction means. Note that the gas tube 58 is disposed in the vicinity of the above-described magnetic field, for example, at a position slightly below the anode 42 in order to efficiently discharge (ionize) the reactive gas in the discharge cleaning process and the film forming process described later. It arrange | positions so that gas may be ejected. In addition, a mass flow controller 60 as a flow rate adjusting means for adjusting the flow rate of the reactive gas flowing in the gas pipe 58 is provided outside the vacuum chamber 12.

  Further, each object to be processed 36, 36,... Is supplied from a high frequency power supply device 64 as a bias supply means via holders 34, 34,. 36,... Is supplied with high frequency power Eb having a frequency of 13.56 MHz. The matching box 62 is for matching the impedance between the high frequency power supply device 62 and the load side including the workpieces 36, 36,.

  Here, the high frequency power Eb includes a negative DC component Vdc with reference to the ground potential, as shown in FIG. The voltage value of the direct current component Vdc can be arbitrarily set in the range of 0 V to −200 V, for example, by the high frequency power supply device 64. When the voltage value of the direct current component Vdc is changed, the high frequency power supply device 64 The voltage amplitude value Vpp of the electric power Eb changes, and consequently the electric power value of the high frequency electric power Eb itself changes. On the contrary, the power value of the high frequency power Eb itself can be arbitrarily set by the high frequency power supply device 64. When the power value of the high frequency power Eb is changed, the voltage value of the DC component Vdc changes. .

  As described above, the high frequency power Eb including the DC component Vdc is supplied to each of the objects to be processed 36, 36,... In this embodiment, the voltage control circuit 66 as control means is used to stabilize the DC component Vdc. Is provided. That is, the voltage control circuit 66 acquires the voltage value of the DC component Vdc from the matching box 62, and the high frequency power supply device 64 (DC component Vdc) so that the acquired voltage value matches the set value by the high frequency power supply device 64. To control. With this so-called feedback control, the voltage value of the DC component Vdc is stabilized with an accuracy of ± 1 V or less with respect to the set value by the high frequency power supply device 64.

  According to the film forming apparatus 10 having such a configuration, for example, a hard BN film having the above-described composition ratio (N / B ratio) of 0.6 to 1.1 can be generated. Specifically, prior to the BN film forming process, a discharge cleaning process is first performed. Then, after this discharge cleaning process, a TiN film forming process as an intermediate layer is performed, followed by a BN film forming process. When the TiN film and the BN film are to be generated as described above, solid crucible material and boron material are individually accommodated as the evaporation material 20 in the crucible 22 described above. These titanium and boron materials are selectively heated by the electron gun 24. In addition, as the above-described reactive gas, for example, argon gas as a discharge gas and nitrogen gas as a material gas are individually introduced into the vacuum chamber 12 through a gas pipe 58.

First, in the discharge cleaning process, the inside of the vacuum chamber 12 is evacuated by a vacuum pump, and a high vacuum state of about 1 × 10 ⁻⁴ Pa is set. .. Are heated to about 300 ° C. by the heater 26, and then argon gas is introduced into the vacuum chamber 12 through the gas pipe 58. The pressure in the vacuum chamber 12 in a state where the argon gas is introduced is, for example, about 6.67 × 10 ⁻² Pa. In this state, the cathode power Ec is supplied from the cathode heating power supply device 44 to the cathode 40. As a result, the cathode 40 is heated and emits thermoelectrons. When the anode voltage Va is applied to the anode 42 from the anode power supply device 48, the thermoelectrons are accelerated toward the anode 42. In this acceleration process, the thermoelectrons collide with argon gas particles. As a result, the argon gas particles are discharged and plasma is generated. Here, as described above, the DC cathode bias voltage Vcb is superimposed on the AC cathode power Ec supplied to the cathode 40. Accordingly, the thermal electrons are accelerated according to the sum of the cathode bias voltage Vcb and the above-described anode voltage Va. In this way, as an energy source for accelerating the thermoelectrons, in addition to the anode voltage Va, a cathode bias voltage Vcb is applied to stabilize the plasma.

  Further, as described above, a magnetic field is generated in the space where the cathode 40 and the anode 42 are disposed. Therefore, the plasma generated between the cathode 40 and the anode 42 is confined in the magnetic field, As a result, as shown by the broken line pattern 68 in FIGS. When the motor 32 is driven, the workpieces 36, 36,... Are sequentially conveyed to the plasma region 68 by the revolving action of the self-revolving mechanism 28. In the plasma region 68, the surface of each object 36 is uniformly exposed to the plasma (directed toward the plasma center) by the rotation of the rotation mechanism 28.

  Here, when the high frequency power Eb is supplied from the high frequency power supply device 64 to the objects to be processed 36, 36,..., In the plasma region 68, the argon ions in the plasma are on the surfaces of the objects to be processed 36, 36,. Is irradiated. And the surface of each to-be-processed object 36,36, ... is wash | cleaned by the impact by this ion irradiation, ie, a discharge cleaning process is performed.

  In addition, the revolution speed of each to-be-processed object 36,36, ... is 1 rpm, for example. Further, the spread angle of the plasma region 68 (the opening angle of the magnetic field generators 50 and 52) is, for example, 60 degrees with the central axis of the vacuum chamber 12 as the center. Therefore, each of the workpieces 36, 36,... Is subjected to a so-called intermittent discharge cleaning process for 10 seconds per minute. Further, since each of the workpieces 36, 36,... Rotates at 10 times the revolution speed, that is, 10 rpm, the entire surface is uniformly subjected to the discharge cleaning process.

  After the discharge cleaning process, a TiN film forming process is performed. Specifically, a Ti film, a TiN film, and a Ti film are sequentially generated by the following procedure.

That is, as described above, only the titanium material of the evaporation material 20 is heated by the electron gun 24 in a state where the inside of the vacuum chamber 12 is maintained at about 6.67 × 10 ⁻² Pa in an argon gas atmosphere. The heated titanium material is evaporated and ionized in the plasma region 68. The titanium ions are irradiated on the surfaces of the objects to be processed 36, 36,... In the plasma region 68, whereby titanium is deposited on the surfaces of the objects to be processed 36, 36,. Generated. This Ti film forming process is performed for about 2 minutes. In the film forming process of each coating film including the Ti film, which will be described later, the film forming process is performed for each object 36 for 10 seconds (intermittently) per minute.

Next, in addition to the argon gas, nitrogen gas is introduced into the vacuum chamber 12. Also at this time, the pressure in the vacuum chamber 12 is maintained at about 6.67 × 10 ⁻² Pa. Nitrogen gas introduced into the vacuum chamber 12 is ionized in the plasma region 68. And this nitrogen ion is irradiated to the surface (on Ti film | membrane) of the to-be-processed objects 36,36, ... in the plasma area | region 68 with the above-mentioned titanium ion. As a result, titanium nitride, which is a compound of nitrogen and titanium, is deposited on the surfaces of the objects to be processed 36, 36,... To produce a TiN film. This TiN film forming process is performed for about 80 minutes.

  Then, after the time of 80 minutes has elapsed, the introduction of nitrogen gas is stopped. Thus, the Ti film is formed again in the same manner as described above. This re-forming process of the Ti film is also performed for about 2 minutes, thereby completing the forming process of the TiN film having a three-layer structure of Ti / TiN / Ti.

  Subsequent to the TiN film forming process, a BN film forming process is performed. Specifically, a B film is generated to improve adhesion with the TiN film. Then, a BN film is generated on the B film. Further, in the process of generating the BN film, the composition ratio of nitrogen to boron is increased stepwise, thereby gradually increasing the hardness of the BN film, and finally the composition ratio is 0.6 to 1.1. A hard BN film is produced. The BN film generated between the lowermost B film and the uppermost hard BN film functions as an intermediate layer for improving the adhesion between the B film and the hard BN film. That is, a film having a three-layer structure of B / BN intermediate layer / hard BN is generated as the entire BN film.

  In order to generate such a BN film, first, a boron material is heated by the electron gun 24 instead of the titanium material in the crucible 22. The heated boron material evaporates and some of it is ionized in the plasma region 68. The boron ions are applied to the surfaces of the objects to be processed 36, 36,... In the plasma region 68 (on the TiN film). As a result, boron is deposited on the surfaces of the workpieces 36, 36,..., And a B film is generated.

Next, nitrogen gas is introduced into the vacuum chamber 12. The introduced nitrogen gas is ionized in the plasma region 68. The nitrogen ions are irradiated together with boron ions on the surfaces of the objects to be processed 36, 36,... In the plasma region 68 (on the B film), whereby the surfaces of the objects to be processed 36, 36,. Then, boron nitride which is a compound of nitrogen and boron is deposited, and a BN film is generated. Furthermore, in the process of forming the BN film, the flow rate of nitrogen gas is increased stepwise. In other words, the ratio of the nitrogen gas flow rate to the argon gas flow rate is increased stepwise. In addition, the pressure in the vacuum chamber 12 is maintained at about 6.67 × 10 ⁻² Pa as described above. In this way, the flow rate of nitrogen gas (flow rate ratio to argon gas) is increased stepwise, so that the composition ratio of boron and nitrogen constituting the BN film changes stepwise. The composition ratio increases stepwise, and finally a hard BN film is generated. Further, in the process of generating the BN film, the voltage value of the direct current component Vdc included in the high frequency power Eb is increased stepwise in order to further improve the adhesion.

  By a series of these film forming processes, as shown in FIG. 5, a TiN film and a BN film are generated in this order on the surface of the workpiece 36. Further, as shown in FIG. 6, the BN film is formed by laminating a plurality of layers 100, 100,... Having different composition ratios of boron and nitrogen.

  Here, when the DC component Vdc changes in the generation process of each layer 100, an electric field fluctuation occurs in the layer 100. In some cases, that is, when the electric field fluctuation is large, reference numerals 102, 102,. As shown, the layer 100 is broken. The degree of destruction becomes more prominent as the amount of change in the DC component Vdc increases. As shown exaggeratedly in FIG. 8, when the broken portions 102, 102,... Become more prominent in each layer 100, the broken portions 102, 102,. Cracks 104, 104,... Penetrating through the respective layers 100, 100,. When the BN film containing the cracks 104, 104,... (Processed objects 36, 36,...) Is exposed to the atmosphere, moisture and gas are adsorbed on the cracked portions 104, 104,. Alternatively, the portion is oxidized, and the BN film is partially peeled off as indicated by reference numeral 106 in FIG. And this partial peeling arises in a chain | linkage in the place where the crack 104,104, ... entered. As a result, the BN film peels in a pulverized manner (so-called shattered).

  In the prior art described above, it is estimated that the BN film (cBN film) is peeled off due to such a cause. That is, when the power value itself of the high-frequency power supplied to the substrate is increased stepwise, the DC component (Vdc) greatly fluctuates with this, thereby causing a crack in the BN film and peeling off the BN. Presumed to be. As evidence, it has been confirmed that in the prior art, when the TiN film as the protective film is not formed, the BN film is pulverized as described above.

  Therefore, in this embodiment, the BN film is formed under the following conditions.

  That is, the anode voltage Va is constant at 40V. The anode current Ia flows through the anode 42 by the application of the anode voltage Va. The anode current Ia is constant at 70A. The anode current Ia is determined by the amount of thermoelectrons emitted from the cathode 40 as described later, that is, the anode current Ia is determined by the power value of the cathode power Ec supplied to the cathode 40 (heating temperature of the cathode 40). Further, the cathode bias voltage Vcb is kept constant at −24V. The flow rate of argon gas is kept constant at 55 mL / min. Further, as shown in FIG. 10, the film forming process is performed for 70 minutes. At this time, the flow rate of the nitrogen gas, the electron gun power, and the direct current component are adjusted as needed. Specifically, the flow rate of nitrogen gas is increased stepwise in the range of 0 mL / min to 45 mL / min. The electron gun power is 4.5 kW during the film forming process time from 0 to 21 minutes, and 4.0 kW after the 21 minutes. The voltage value of the direct current component Vdc is increased stepwise in the range of 0V to −80V. The amount of increase (voltage rise value) per step of the DC component Vdc is 5 V (except for the first step (excluding the step where the processing time shifts from 1 minute to 2 minutes)). In other words, the increase amount of the DC component Vdc in 1 minute is set to 5 V or less. And according to this direct-current component Vdc, the electric power value of the high frequency electric power Eb also increases in steps. As will be described later, the cathode bias current Icb flowing between the cathode 40 and the ground potential also increases in accordance with the DC component Vdc.

  In the film forming process under such conditions, a BN film is generated in the above-described manner. In the generation process, charges due to ion irradiation are formed on the BN film (the surfaces of the objects to be processed 36, 36,...). Accumulated. Then, electrons are procured from the discharge space (plasma region 68) in order to cancel this charge. As a result, electrons are insufficient in the discharge space, and the current value of the anode current Ia decreases. When the anode current Ia decreases in this way, the plasma becomes unstable. In this embodiment, the cathode power Ec is controlled so that the anode current Ia is constant. That is, the cathode power Ec is increased, and thermoelectrons are additionally emitted from the cathode 40. This compensates for the shortage of electrons in the discharge space and stabilizes the plasma. As the thermal electron emission amount from the cathode 40 increases, the cathode bias current Icb gradually increases from 50A to 90A as described above. In this embodiment, the cathode power Ec is automatically controlled by the cathode heating power supply device 44. However, the cathode power Ec may be controlled manually (artificially). Further, under the conditions of FIG. 10, the cathode power Ec varies in a range of about 1150 W (9 V / 125 A) to 1540 W (11 V / 140 A).

  FIG. 11 is a graph showing the transition of the voltage value of the DC component Vdc and the current value of the cathode bias current Icb. As is apparent from FIG. 11, it can be seen that the current value of the cathode bias current Icb increases in accordance with the voltage value of the DC component Vdc. This means that the shortage of electrons in the discharge space is compensated by the thermal electrons emitted from the cathode 40 as described above. In this film forming process, a hard BN film having a film thickness of 0.9 μm to 1.1 μm and a composition ratio of the uppermost layer of 0.8 or more, specifically 0.9 to 1.0 is generated. The And it was confirmed that this BN film does not peel, that is, a practical hard BN film is produced.

  Next, as a control experiment of this embodiment, it was examined how the cathode bias current Icb changes when the above-described peeling occurs. That is, instead of FIG. 10 described above, a BN film was formed under the conditions shown in FIG.

  Specifically, the flow rate of nitrogen gas is increased stepwise in the range of 0 mL / min to 40 mL / min. The electron gun power is set to 5.0 kW when the film forming process time is 0 minute to 2 minutes, 4.5 kW between 2 minutes to 21 minutes, and 4.0 kW thereafter. Then, the voltage value of the DC component Vdc is increased stepwise in the range of 0V to −80V. Note that the increase amount per one step of the direct current component Vdc is larger than that in the case of FIG. 10 (5 V). The transition of the voltage value of the DC component Vdc and the current value of the cathode bias current Icb at this time is shown in a graph in FIG.

  As can be seen from FIG. 13, even if the voltage value of the DC component Vdc is increased, the current value of the cathode bias current Icb hardly changes. In other words, the cathode power Ec does not change. This means that cracks 104, 104,... As shown in FIG. That is, it means that electrons are supplied from the object to be processed 36 through the cracks 104, 104,... To cancel out charges accumulated on the BN film by ion irradiation. Thus, since electrons are supplied from the workpiece 36 itself, the amount of emitted thermal electrons from the cathode 40 does not increase, and the cathode bias current Icb does not increase. In addition, such a state is the same as the production | generation process of an electroconductive film. The film forming process under such conditions produces a BN film having a film thickness of 0.6 μm to 0.8 μm for the time being. This BN film is pulverized and peeled as soon as it is exposed to the atmosphere. To be confirmed.

  As described above, according to this embodiment, when the hard BN film is generated, the fluctuation of the direct current component Vdc that induces the destruction of the BN film (layers 100, 100,...) Is suppressed. Therefore, a practical hard BN film that does not cause destruction (peeling) can be generated. Moreover, according to this embodiment, when the to-be-processed object 36 has sharp parts, such as a blade edge | tip, there also exists an effect that the said BN film | membrane can be produced | generated appropriately also at this sharp part.

  That is, when the workpiece 36 has a sharp portion, the current flowing through the workpiece 36 due to the supply of the high frequency power Eb (DC component Vdc) is concentrated on the sharp portion. In addition, when a BN film is generated at this sharp portion, the BN film acts as a dielectric, and the voltage at that portion further increases. Thereby, the irradiation energy of ions to the sharp portion increases. Here, in the case of the above-described prior art, the etching (bombarding) action by the collision of the ions is more dominant than the BN film formation (deposition) effect, and the increase degree of the high-frequency power (DC component) is relatively high. Since it is large, a BN film is not generated for the sharp part. On the other hand, in this embodiment, the electric charge concentrated on the sharp part is canceled out by the thermal electrons replenished from the cathode 40, and the increase degree of the direct current component Vdc is relatively small at 5 V or less per minute. A BN film is gradually and reliably formed on the sharp portion. Thus, according to this embodiment, a BN film can be generated uniformly over the entire surface of the workpiece 36 including a sharp portion.

  In addition, in this embodiment, although the drill which uses high speed steel as a base material was used as the to-be-processed object 36, it is not restricted to this. That is, a base material made of a metal other than high speed steel and a base material other than a drill may be applied as the workpiece 36.

Moreover, although the case where the BN film | membrane, especially a hard BN film | membrane was produced | generated as a film was demonstrated, the cBN film | membrane mentioned above can also be produced | generated. In addition to these BN films, other insulating films such as AlN (aluminum nitride) films, SiN (silicon nitride) films, SiO ₂ (silicon oxide films), and TiO ₂ (titanium oxide) films are generated. You can also Furthermore, not only an insulating film but a conductive film can also be produced. However, as described above, the present invention is particularly effective for producing an insulating film.

  The number of holders 34 to which the workpiece 36 is attached is not limited to the number described above (72), and may be a single number, for example. Moreover, the holder 34 does not need to revolve or rotate.

  Further, although the magnetic field generators 50 and 52 are inclined, the present invention is not limited to this. That is, they may be opposed to each other without being inclined. The same applies to the anode 42.

  Furthermore, the shapes and dimensions of the elements constituting this embodiment such as the vacuum chamber 12 are not limited to the aspects described here. For example, the vacuum chamber 12 may have a shape other than a substantially cylindrical shape, and the diameter C and depth D of the vacuum chamber 12 are not limited to the above-described values.

  Moreover, although argon gas was used as the discharge gas, other gases such as helium (He) gas, neon (Ne) gas, krypton (Kr) gas, xenon (Xe) gas, or the like are used. Alternatively, a plurality of types of gases may be used in combination.

  The high frequency power Eb is used as the bias power supplied to the workpiece 36, but pulse power may be used instead. In this case, the duty ratio may be arbitrarily changed.

  Furthermore, although the TiN film is generated as the intermediate layer, other intermediate layers may be generated. Further, depending on the type of coating, the intermediate layer may not be provided.

  The voltage value of the DC component Vdc is increased stepwise, but may be increased continuously. However, also in this case, it is important that the degree of increase of the DC component Vdc is 5 V or less per minute.

It is an internal front view which shows schematic structure of one Embodiment of this invention. It is AA arrow sectional drawing in FIG. It is BB arrow sectional drawing in FIG. It is an illustration figure which shows the voltage waveform of the high frequency electric power Eb supplied to a to-be-processed object in the same embodiment. It is an expanded sectional view of the to-be-processed object after performing the film-forming process in the same embodiment. It is an illustration figure which further expands and shows the part of the film in FIG. FIG. 5 is an illustrative view showing a state in which a film is broken in FIG. 4. FIG. 8 is an illustrative view showing a state in which the destruction of FIG. 7 is remarkable. It is an illustration figure which shows the state from which a film peels by destruction of FIG. It is a list which shows the conditions of the film-forming process in the embodiment. 11 is a graph showing changes in DC component Vdc and cathode bias current Icb in FIG. 10. It is a list which shows the film-forming conditions in the control experiment of the embodiment. 13 is a graph showing transitions of the DC component Vdc and the cathode bias current Icb in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Film-forming apparatus 12 Vacuum tank 34 Holder 36 To-be-processed object 40 Cathode 42 Anode 44 Cathode heating power supply device 46 Cathode bias power supply device 48 Anode power supply device 50, 52 Magnetic field generator 58 Gas pipe 64 High frequency power supply device 66 Voltage control Circuit 68 Plasma region

Claims (6)

In a film forming apparatus that generates a film on the surface of an object to be processed by an ion plating method,
Bias supplying means for supplying an AC bias power with a DC component superimposed thereon to the workpiece;
Control means for controlling the DC component;
A film forming apparatus comprising:   The film forming apparatus according to claim 1, wherein the control unit gradually increases the DC component.   The film forming apparatus according to claim 2, wherein an increase amount of the DC component per minute is 5 V or less.   The film forming apparatus according to claim 1, wherein the coating is an insulating coating.   The film forming apparatus according to claim 4, further comprising an electron supply unit that supplies electrons to the discharge space for canceling out charges accumulated on the surface of the object to be processed when ions are irradiated on the surface. In a film forming method for generating a film on the surface of an object to be processed by an ion plating method,
A bias supply process for supplying an AC bias power superimposed with a DC component to the workpiece;
A control process for controlling the DC component;
The film-forming method characterized by comprising.

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