JP2012199017A - Pressure gradient plasma generating device and deposition device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure gradient plasma generating device in which damage of a first intermediate electrode can be prevented, and the magnetic field intensity can be changed easily.SOLUTION: The pressure gradient plasma generating device has a negative electrode, first and second intermediate electrodes, and a positive electrode in order. The first and second intermediate electrodes have an orifice of a predetermined size, separately. An electromagnet is arranged in the first intermediate electrode 2. The electromagnet includes a plurality of coils 51-54 arranged in the circumferential direction so as to surround an orifice 2a. Consequently, loop-like magnetic field lines 55 on the outside and loop-like magnetic field lines 56 on the inside can be formed as if permanent magnets are arranged annularly. A magnetic field can thereby be formed in the orifice 2a, and parallel magnetic fields 57, 58 can be formed on the side surface on negative electrode side over a wide range.

Description

  The present invention relates to a pressure gradient type plasma generator using arc discharge.

  A plasma generator of a pressure gradient type that protects the vicinity of the cathode with a high inert gas pressure and prevents damage to the cathode due to ion collision in the plasma while generating a high-density plasma by direct current discharge. Membrane devices are described in Patent Documents 1 and 2.

  Conventionally, a plasma source using an arc discharge such as a hollow cathode method has a problem that a hot cathode is severely damaged and has a short life. In the pressure gradient type plasma gun described in Patent Documents 1 and 2, the first and second intermediate electrodes having a small through hole (orifice) at the center are arranged between the cathode and the anode, and the conductance of the gas passing therethrough This problem is solved by forming a pressure difference (pressure gradient) between the cathode region and the anode region, and by gradually forming a potential gradient between the cathode and the anode.

That is, the pressure gradient type plasma gun can maintain the pressure in the cathode region around 10 Pa and the pressure in the anode region around 0.1 Pa with the intermediate electrode. For this reason, the mean free path of ions in the cathode region can be extremely shortened, and damage to the cathode due to ion backflow collision from the anode region can be avoided. Further, even when a chemically activated gas (O ₂ , N _2, etc.) is introduced into the anode region to form a mixed plasma, the pressure of the inert gas filling the cathode region is about 10 ³ times higher than that of the anode region. The chemical active gas can be prevented from flowing into the cathode region, and chemical damage to the cathode can be avoided.

  In order to maintain discharge with the structure in which the first and second intermediate electrodes are arranged, a sufficient amount of electrons must pass through a small orifice. Therefore, a ring-shaped permanent magnet is arranged in the first intermediate electrode located on the cathode side, a cylindrical coil-shaped electromagnet is arranged in the second intermediate electrode located on the anode side, and the cathode is placed in the orifice. A magnetic field toward the anode is formed. The electrons travel along this magnetic field to converge within the orifice, allowing a sufficient amount of electrons to pass through the intermediate electrode.

By using such a pressure gradient type plasma gun, it is possible to evaporate many metals and dielectrics, or to activate the evaporated materials, and to obtain an excellent thin film according to Patent Document 2 and the like It has been reported. Forming a ferroelectric or piezoelectric material typified by PZT (Pb (Zr _x Ti _1-x ) O ₃ ), a perovskite oxide, on a thin film with good crystallinity at a relatively low deposition temperature Can do.

JP 2007-305336 A Japanese Patent No. 4138196

  In the conventional pressure gradient plasma gun, a ring-shaped permanent magnet is arranged in the first intermediate electrode closest to the cathode, and an electromagnet is used in the second intermediate electrode on the anode side. Is to prevent. In the space on the cathode side of the first intermediate electrode, a large amount of thermoelectrons are present at a high pressure of about 10 Pa, and therefore the surface on the cathode side of the first intermediate electrode is sputtered and damaged by ions generated by the thermoelectrons. At this time, if there is a magnetic field parallel to the side surface on the cathode side of the first intermediate electrode, ions move along the magnetic field, so that damage to the side surface of the first intermediate electrode can be reduced. By using a permanent magnet, a magnetic field parallel to the side surface can be formed over a wide range of the side surface on the cathode side of the first intermediate electrode. For this reason, a permanent magnet is used as the magnetic field generating means for the first intermediate electrode.

  The optimum value of the strength of the magnetic field in the orifice (through hole) of the first intermediate electrode varies depending on the gas type, the gas flow rate, the magnitude of the discharge current, and the like. Conventionally, since an electromagnet (coil) is used in the second intermediate electrode, the strength of the magnetic field can be easily changed by changing the magnitude of the current flowing through the coil. However, in the case of the first intermediate electrode, the strength of the magnetic field cannot be changed unless the permanent magnet is replaced.

  Specifically, the method for replacing the permanent magnet of the first intermediate electrode is to stop the film forming apparatus and the plasma gun, bring the inside to atmospheric pressure, take out the first intermediate electrode from the plasma gun, replace the permanent magnet, The first intermediate electrode is attached to the plasma gun, the inside of the film forming apparatus and the plasma gun is evacuated to generate plasma, and the state of the plasma is observed to determine whether or not the optimum magnetic field strength has been reached. This procedure must be repeated and replaced with permanent magnets having different magnetic field strengths until an optimum plasma state is obtained. For this reason, there is a problem that it takes a very long time to adjust the magnetic field strength. In addition, a plurality of permanent magnets having different magnetic field strengths must be prepared in advance. Furthermore, even if the gas type or gas flow rate is changed during the film forming process, the magnetic field strength cannot be changed during the process.

  An object of the present invention is to provide a pressure gradient type plasma generator capable of preventing damage to a first intermediate electrode and easily changing the magnetic field strength.

  In order to achieve the above object, according to the first aspect of the present invention, the following plasma generator is provided. That is, a pressure gradient type plasma generator having a cathode, first and second intermediate electrodes, and an anode, which are arranged in order, both of the first intermediate electrode and the second intermediate electrode being anodes from the cathode side. An orifice of a predetermined size penetrating to the side is provided. The first intermediate electrode has an electromagnet disposed therein, and the electromagnet includes a plurality of coils disposed along the circumferential direction so as to surround the orifice.

  As the plurality of coils, a coil formed by winding a coil wire in a flat shape can be used. Each of the plurality of coils may have a shape in which a coil wire is wound along a circumferential direction around an arc obtained by dividing a predetermined circumference surrounding the orifice.

  According to another aspect of the present invention, the following plasma generator is provided. That is, a pressure gradient type plasma generator having a cathode, first and second intermediate electrodes, and an anode, which are arranged in order, both of the first intermediate electrode and the second intermediate electrode being anodes from the cathode side. An orifice of a predetermined size penetrating to the side is provided. The first intermediate electrode has an electromagnet disposed therein, and the electromagnet includes one or more coils each having a shape in which a coil is wound along a circumferential direction around one or more arcs dividing the circumference surrounding the orifice. Including.

  The magnetic field formed by the coil forms a magnetic field line that draws a loop that returns to the inside of the coil through the outer peripheral region of the coil, and a magnetic field line that draws a loop that returns to the inside of the coil through the region on the orifice side of the coil. desirable. The electromagnet forms a magnetic field from the cathode to the anode in the orifice of the first intermediate electrode, and is a magnetic field parallel to the surface of the side surface facing the cathode of the first intermediate electrode. It is desirable to form a magnetic field from the orifice toward the outer periphery and in the inner region from the outer periphery toward the orifice.

  In the present invention, by arranging a plurality of coils along the circumferential direction in the first intermediate electrode, it is possible to form magnetic lines of force similar to the case where a permanent magnet is arranged with an electromagnet. Can be adjusted easily. In addition, since a magnetic field parallel to the surface can be formed in a wide range on the side surface on the cathode side of the first intermediate electrode, damage to the side surface on the cathode side of the first intermediate electrode can be prevented.

1 is a block diagram showing the overall configuration of an arc discharge ion plating apparatus according to a first embodiment. The block diagram which shows the structure of the plasma gun 10 of the apparatus of FIG. FIG. 3 is a block diagram showing the arrangement of the coil in the first intermediate electrode 2 of the plasma gun of the apparatus of FIG. 2 as viewed from the cross-sectional direction including the axis 101, and FIG. Explanatory drawing which shows arrangement | positioning of the coil in the 1st intermediate electrode 2 of FIG. 2, and the shape of a magnetic force line. Explanatory drawing which shows the shape of the permanent magnet in the 1st intermediate electrode 120 of the comparative example 1, and the shape of a magnetic force line. Explanatory drawing which shows the shape of the solenoid coil in the 1st intermediate electrode 220 of the comparative example 2, and a magnetic force line. Explanatory drawing which shows the arrangement | positioning which looked at the coil and core of the 1st intermediate electrode of 2nd Embodiment from the cathode. Explanatory drawing which shows the arrangement | positioning which looked at the coil and yoke of the 1st intermediate electrode of 3rd Embodiment from the cathode.

  Hereinafter, an embodiment of the present invention will be described.

(First embodiment)
First, an arc discharge ion plating apparatus will be described with reference to FIGS. 1 and 2 as a film forming apparatus using the plasma gun of the first embodiment. FIG. 1 is an overall view of the arc discharge ion plating apparatus, and FIG. 2 is an enlarged view of the plasma gun 10. The plasma gun 10 is a reflection type that reflects an electron flow and a pressure gradient type.

  As shown in FIG. 1, a substrate holder 13 for supporting a substrate 14 to be deposited, an evaporation source 12, and an electron beam gun (not shown) for irradiating the evaporation source 12 with an electron beam are provided in the vacuum container 11. Has been placed. The substrate holder 13 incorporates a heater for heating the substrate 14. Further, a reaction gas introduction pipe 15 for supplying a reaction gas to the space between the substrate 14 and the evaporation source 12 is disposed.

  A plasma gun 10 is provided on the side surface of the vacuum vessel 11. As shown in FIGS. 1 and 2, the plasma gun 10 has a cathode 1, a first intermediate electrode 2, a second intermediate electrode 3, and an anode 4 arranged in this order along a plasma extraction axis 101 in a cylindrical plasma gun container 103. This is the structure. The cathode 1, the first intermediate electrode 2, the second intermediate electrode 3, and the anode 4 are insulated from one another by an insulator (not shown). An air-core coil 5 for guiding plasma is disposed on the outer peripheral side of the anode 4.

  The cathode 1 has a known cathode structure suitable for arc discharge. The cathode 1 is provided with a discharge gas inlet 102.

  A DC power source 16 is connected to the cathode 1 and the anode 4 as shown in FIGS. The first and second intermediate electrodes 2 and 3 are connected to the positive electrode of the DC power supply 16 through the enamel resistors 20 and 21 having appropriate resistance values. The values of the enamel resistors 20 and 21 are set so that the first and second intermediate electrodes 2 and 3 have higher potential as they are closer to the anode 4 side from the cathode 1 side. Thereby, plasma can be drawn out to the vacuum vessel 11.

  The first and second intermediate electrodes 2 and 3 have through holes (orifices) 2a and 3a having predetermined diameters at the centers, respectively, and the orifices 2a and 3a control the pressure of the plasma gun container 103 to the vacuum container 11 Rather than maintaining a positive pressure to form a pressure gradient. The first and second intermediate electrodes 2 and 3 have built-in electromagnets 50 and 60, respectively. These generate a magnetic field for converging plasma to pass through the through holes 2a and 3a. In the prior art, the first intermediate electrode 2 has a built-in permanent magnet. However, in the present embodiment, by using the electromagnet 50, the magnetic field strength is made variable by adjusting the current strength.

  Specifically, as shown in FIGS. 3A, 3 </ b> B, and 4, the electromagnet 50 surrounds the orifice 2 a with two or more coils in the space in the main body 2 b of the first intermediate electrode 2. The structure is arranged along the circumferential direction. It is preferable that two or more coils have a flat shape because the orifice can be surrounded by a small number of coils. In particular, when a coil having a saddle type structure in which a coil wire is wound in the circumferential direction so as to be along the outer side and the inner side of the circular arc around the circular arc divided into a plurality of circumferences, the outer peripheral side of the electromagnet 50 is used. This is preferable because a uniform magnetic field can be formed in a wide range in the circumferential direction on the region and on the inner side (orifice 2a side region).

  In the example of FIGS. 3 and 4, the four saddle coils 51 to 54 are arranged so as to surround the orifice 2 a. Each of the saddle-shaped coils 51 to 54 has a coil wire wound in the circumferential direction around the arc of about 90 degrees obtained by dividing the circumferential direction of the first intermediate electrode 2 into four so as to be along the outer side and the inner side of the arc. This is a saddle type air core coil.

  Note that the number of coils constituting the electromagnet 50 is not limited to four, but can be any number. Further, the electromagnet 50 can be constituted by one coil. For example, a coil having a saddle type structure in which a coil wire is wound in the circumferential direction so as to be along the outer side and the inner side of the circular arc around a circular arc slightly smaller than 360 ° with a small part of the circumference cut off. be able to.

  Hereinafter, the case where the coils 51 to 54 having the structures of FIGS. 3A and 3B and FIG. 4 are used will be described as an example. As shown in FIG. 3B, by supplying current to the four saddle coils 51 to 54 so that current flows counterclockwise as viewed from the cathode 1 side, A magnetic field is generated around the coils 51 to 54 as shown in FIGS. These magnetic fields go through the space on the outer peripheral side of each coil 51 to 54 in the direction from the cathode 1 to the anode 4, and the magnetic field lines 55 of the outer loop that return the air core portion of each coil from the anode 4 toward the cathode 1, and each coil The inner loop magnetic field lines 56 are formed so that the space on the orifice 2a side of 51 to 54 advances from the cathode 1 to the anode 4 and the air core of each coil returns from the anode 4 to the cathode 1.

  As a result, a magnetic field parallel to the axis 101 is formed in the orifice 2a in the direction from the cathode 1 to the anode 4, and the plasma 105 can be converged and passed through the orifice 2a.

  Magnetic fields 57 and 58 parallel to the surface of the main body 2b of the first intermediate electrode 2 are formed on the side surface of the first intermediate electrode 2 on the cathode 1 side by the outer magnetic lines 55 and the inner magnetic lines 56, respectively. . That is, a magnetic field 57 outward from the central axis 101 is formed in the outer peripheral side region on the side surface on the cathode 1 side of the main body 2b of the first intermediate electrode 2, and a magnetic field 58 toward the central axis 101 is formed in the peripheral region of the orifice 2a. Are formed, and these magnetic fields 57 and 58 are parallel to the surface of the main body 2 b of the first intermediate electrode 2.

  As described above, in this embodiment, the magnetic lines 55 and 56 of the inner loop and the outer loop are formed, so that the magnetic fields 57 and 58 parallel to the surface of the first intermediate electrode 2 on the cathode 1 side are formed over a wide area. Can do. Therefore, ions generated by the thermoelectrons generated by the cathode 1 can be moved in parallel to the surface of the first intermediate electrode 2 by the magnetic fields 57 and 58, and the ions collide with the surface of the first intermediate electrode 2 to cause sputtering. The phenomenon of damage can be prevented.

  The shape of the magnetic lines 55 and 56 formed by the saddle coils 51 to 54 is the same as the magnetic lines 155 and 156 of the intermediate electrode 120 incorporating the conventional ring-shaped permanent magnet 150 shown in FIG. It is. Therefore, the shapes of the magnetic fields 57 and 58 formed in parallel to the surface of the first intermediate electrode 2a are the same as the shapes of the magnetic fields 157 and 158 formed by the permanent magnet 150.

  From these facts, the first intermediate electrode 2 of the present embodiment uses a flat coil, so that the surface of the cathode 1 side is damaged in the same manner as the ring-shaped permanent magnet 150 although the electromagnet 50 is used. Can be prevented.

  Further, since the magnetic field generating means built in the first intermediate electrode 2 of the present embodiment is an electromagnet, the magnetic field strength can be easily adjusted by adjusting the amount of current to be supplied. Therefore, a magnetic field having an optimum magnitude can be formed in the orifice 2a according to the gas type, gas flow rate, discharge current magnitude, and the like. In addition, the magnitude of the magnetic field can be easily changed, and the magnetic field in the orifice 2a can be adjusted while maintaining the state in which the plasma 105 is generated. Therefore, unlike a permanent magnet, the magnetic field in the orifice 2a can be adjusted easily in a short time without breaking the vacuum, and even in the state where the plasma 105 is generated, thereby improving the production efficiency. .

  FIG. 6 shows a magnetic field in the case where a solenoid coil 250, in which a coil is wound in a cylindrical shape, is arranged in the first intermediate electrode 220 so that the central axis coincides with the orifice 2a as Comparative Example 2. When one solenoid coil 250 is arranged in the first intermediate electrode 220, the magnetic field lines 250 are advanced in the direction from the cathode 1 to the anode 4 on the inside of the solenoid coil 250, and return from the anode 4 to the cathode 1 in the outside 1. A kind of loop is formed. Therefore, a magnetic field from the cathode 1 toward the anode 4 can be formed in the orifice 2 a of the first intermediate electrode 220. In addition, a magnetic field 258 parallel to the surface is formed on the side surface of the first intermediate electrode 220 on the cathode 1 side. Unlike the present embodiment, the magnetic field 258 parallel to the surface is only one type. The area where 258 is formed is small. Therefore, the surface region of the first intermediate electrode 220 in which the parallel magnetic field 258 is formed can prevent damage due to sputtering by ions from the cathode 1, but the surface region in which the parallel magnetic field 258 is not formed Damage cannot be prevented.

  As described above, in the present embodiment, by using the first intermediate electrode 2 including the electromagnet 50 in which flat coils are arranged along the circumferential direction, the same magnetic field as that of the first intermediate electrode including the permanent magnet is formed. Thus, plasma can be guided and the cathode side surface of the first intermediate electrode can be protected. Moreover, unlike the permanent magnet, the electromagnet 50 can easily change the strength of the magnetic field formed by adjusting the magnitude of the supplied current.

  On the other hand, as the electromagnet 60 built in the second intermediate electrode 3, a solenoid coil whose center axis coincides with the center axis 101 of the orifice 3a is used as in the conventional case. As a result, a magnetic field from the cathode 1 toward the anode 4 is formed in the orifice 3a, and the plasma 105 is guided. Since the second intermediate electrode 3 is not directly opposed to the cathode 1, there is no fear of damage from ions from the cathode 1 side, and there is no need to form a parallel magnetic field.

  Hereinafter, the operation of each part when producing a thin film element by generating plasma and forming a film on a substrate using the arc discharge ion plating apparatus of FIG. 1 will be described.

  A substrate 14 is attached to the substrate holder 13, and a predetermined solid material is disposed in the evaporation source 12. The inside of the plasma gun 10 and the inside of the vacuum vessel 11 are exhausted to a predetermined pressure. A discharge gas is supplied to the plasma gun 10. Here, He gas with a high ionization voltage is used as the final discharge gas, but in order to stably generate glow discharge, Ar gas with low ionization voltage or a mixture of Ar gas and He gas is used at the start of glow discharge. When the gas is supplied and the glow discharge is stabilized, the ratio of the He gas is increased, and the glow discharge is generated only by the He gas. Thereafter, the arc discharge is performed.

  The arc discharge of the plasma gun 10 is once drawn into the vacuum vessel 11, and the discharge electrons are reflected by the space charge and return to the anode 4. Thereby, a very homogeneous plasma 105 can be generated in the vacuum vessel 11.

  At this time, the first and second intermediate electrodes 2 and 3 provided with the orifices 2a and 2b in the central part reduce the pressure difference (pressure gradient) between the cathode region and the anode region by reducing the conductance of the gas passing therethrough. ) And a gradual potential gradient between the cathode and the anode. Thereby, the pressure in the cathode 1 region is kept high and the anode 4 region is kept at a low pressure, and the mean free path of ions in the cathode 1 region is shortened. Therefore, damage to the cathode 1 due to ion backflow collision from the anode region can be avoided. Further, it is possible to prevent the chemically active gas from flowing into the cathode 1 region from the vacuum vessel 11 side, and chemical damage to the cathode can be avoided.

  The electromagnets 50 and 60 in the first and second intermediate electrodes 1 form a magnetic field from the cathode 1 to the anode 4 in the orifices 2a and 3a, thereby converging the plasma 105 in the orifices 2a and 3a. A sufficient amount of electrons are passed and the plasma 105 is maintained.

  Further, the electromagnet 50 in the first intermediate electrode 1 forms a wide range of magnetic fields 57 and 58 parallel to the side surface of the first intermediate electrode 2 on the cathode 1 side, and ions formed by the thermoelectrons of the cathode 1 are in the first intermediate electrode. It prevents the electrode 1 from colliding and being damaged.

  By supplying oxygen gas from the reaction gas introduction tube 15 in a state where the plasma 105 is generated, the plasma 105 becomes a mixed plasma of He and oxygen. Since He having a higher ionization voltage than Ar is used as the discharge gas, it is possible to supply a larger energy to the oxygen gas than when Ar is used, and a high-density oxygen plasma can be obtained. Therefore, the vapor evaporated from the heated evaporation source 12 passes through the plasma 105 and is oxidized with high efficiency, reaches the substrate 14, and an oxide film can be formed efficiently.

For example, Pb, Zr, and Ti metals are used as the material of the evaporation source 12 and are vaporized independently by electron beam heating, so that they are perovskite type oxides and exhibit the characteristics of ferroelectrics and piezoelectrics. It can be formed on a lead zirconate titanate (PZT: Pb (Zr _x Ti _1-x ) O ₃ ) thin film substrate.

  The optimum value of the strength of the magnetic field in the orifices 2a and 3a of the first and second intermediate electrodes 2 and 3 in the film forming process varies depending on the gas type, the gas flow rate, the magnitude of the discharge current and the like. Therefore, when the gas type is changed from Ar to He during the film formation process, when the gas flow rate is changed, or when the gas flow rate and the magnitude of the discharge current are changed, the inside of the orifices 2a and 3a is changed. It is necessary to adjust the magnitude of the magnetic field to an optimum value. In this embodiment, since the electromagnets 50 and 60 are used as the magnetic field generating means not only in the second intermediate electrode 3 but also in the first intermediate electrode 2, the orifices 2a and 3a can be adjusted by adjusting the current values supplied to them. The magnitude of the internal magnetic field can be changed easily and instantaneously.

  Therefore, unlike the case of using a conventional permanent magnet, it is not necessary to release the vacuum state of the plasma gun container 103 to atmospheric pressure when changing the magnitude of the magnetic field. Thereby, the time required for the adjustment for optimizing the magnetic field strength of the first intermediate electrode can be significantly shortened compared to the conventional case. Even when the gas type, gas flow rate, or the like is changed during plasma generation, the magnitude of the magnetic field can be adjusted while maintaining the state in which the plasma 105 is generated.

  In the above embodiment, the case where He gas is used as the discharge gas has been described, but gases such as Ar, Ne, Xe, and Kr can also be used.

(Second Embodiment)
A second embodiment will be described.

  In the first embodiment, air-core coils are used as the coils 51 to 54 constituting the electromagnet 50 built in the first intermediate electrode 2, but in the second embodiment, each coil 51 to 51 is used as shown in FIG. 7. The core 71 is disposed inside the 54 windings.

  By using the core 71 having a desired magnetic permeability, the distribution of the magnetic lines of force 55 and 57 can be changed, and the magnetic field strength and distribution of the electromagnet 50 can be controlled. Thereby, it is possible to control the distribution of the magnetic fields 57 and 58 on the side surface of the first intermediate electrode 2 on the cathode 1 side and the magnetic field strength in the orifice 2a.

  Other configurations and operations are the same as those of the first embodiment.

(Third embodiment)
A third embodiment will be described.

  In the third embodiment, a ring-shaped yoke 80 is disposed between each of the coils 51 to 54 and the orifice 2a as shown in FIG. By using a yoke 80 having a higher magnetic permeability than air, for example, a ferromagnetic material yoke, the magnetic force lines 56 pass through the yoke 80 with high density. Therefore, by adjusting the size and shape of the yoke 80, the distribution of the magnetic force lines 56 in and around the orifice 2a can be controlled. Thereby, a magnetic field having a desired distribution can be generated in the orifice 2a.

  Other configurations and operations are the same as those of the first embodiment.

  Further, the second and third embodiments can be combined to form the first intermediate electrode 2 including the core 71 and the yoke 80.

  DESCRIPTION OF SYMBOLS 1 ... Cathode, 2 ... 1st intermediate electrode, 3 ... 2nd intermediate electrode, 4 ... Anode, 5 ... Air-core coil, 11 ... Vacuum container, 12 ... Evaporation source, 13 ... Substrate holder, 14 ... Substrate, 15 ... Reaction Gas introduction pipe, 16 ... DC power source, 20, 21, 22 ... Holo resistance, 101 ... Center axis of plasma extraction, 102 ... Discharge gas introduction port, 103 ... Plasma gun container

Claims (11)

A pressure gradient type plasma generator having a cathode, first and second intermediate electrodes, and an anode, arranged in order,
Each of the first intermediate electrode and the second intermediate electrode includes an orifice having a predetermined size penetrating from the cathode side to the anode side,
An electromagnet is disposed inside the first intermediate electrode, and the electromagnet includes a plurality of coils disposed along a circumferential direction so as to surround the orifice.   2. The pressure gradient type plasma generator according to claim 1, wherein the plurality of coils are formed by winding a coil wire in a flat shape.   3. The pressure gradient type plasma generator according to claim 1, wherein each of the plurality of coils is formed by winding a coil wire along a circumferential direction around an arc obtained by dividing a predetermined circumference surrounding the orifice. A pressure gradient type plasma generator characterized by having a rotated shape. A pressure gradient type plasma generator having a cathode, first and second intermediate electrodes, and an anode, arranged in order,
Each of the first intermediate electrode and the second intermediate electrode includes an orifice having a predetermined size penetrating from the cathode side to the anode side,
The first intermediate electrode has an electromagnet disposed therein, and the electromagnet has at least one of a shape in which a coil is wound around a circumference of one or more arcs that divide a circumference surrounding the orifice, along a circumferential direction. The pressure gradient type plasma generator characterized by including the coil of this.   5. The pressure gradient type plasma generator according to claim 1, wherein the magnetic field formed by the coil draws a magnetic field line that draws a loop that returns to the inside of the coil through an outer peripheral side region of the coil. And a line of magnetic force that draws a loop that returns to the inside of the coil through the region on the orifice side of the coil. The pressure gradient type plasma generator according to any one of claims 1 to 5,
The electromagnet in the first intermediate electrode forms a magnetic field from the cathode to the anode in the orifice of the first intermediate electrode, and on the side surface of the first intermediate electrode facing the cathode, the surface of the side surface The pressure gradient type plasma generator is characterized in that a magnetic field is formed from the orifice toward the outer periphery in the outer peripheral region and from the outer periphery to the orifice in the inner region.   The pressure gradient type plasma generator according to any one of claims 1 to 6, wherein a core is disposed inside the coil.   The pressure gradient type plasma generator according to any one of claims 1 to 7, wherein a ring-shaped yoke surrounding the orifice is arranged in a space between the coil and the orifice. A pressure gradient type plasma generator characterized by the above. A film forming apparatus having a vacuum container in which a substrate and a film forming material are disposed, and a pressure gradient type plasma generator connected to the vacuum container,
A film forming apparatus comprising the apparatus according to claim 1 as the pressure gradient type plasma generating apparatus. A method of manufacturing a thin film element that generates plasma using a pressure gradient arc discharge plasma generator and forms a thin film using the plasma,
The plasma generator has a cathode, first and second intermediate electrodes, and an anode, which are arranged in order,
Each of the first intermediate electrode and the second intermediate electrode includes an orifice having a predetermined size penetrating from the cathode side to the anode side,
The first intermediate electrode includes an electromagnet disposed therein, and the electromagnet includes a plurality of coils disposed along a circumferential direction so as to surround the orifice,
A method of manufacturing a thin film element, wherein the magnitude of the magnetic field in the orifice of the first intermediate electrode is adjusted by changing the magnitude of the current supplied to the plurality of coils of the first intermediate electrode.   The method of manufacturing a thin film element according to claim 10, wherein a plasma is formed by applying a predetermined potential to the cathode, the first and second intermediate electrodes, and the anode of the plasma generator, A method of manufacturing a thin film element, wherein the magnitude of the magnetic field in the orifice is adjusted by changing the magnitude of the current supplied to the plurality of coils of the first intermediate electrode while maintaining the plasma.

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