JP6115403B2 - Pressure gradient type plasma gun - Google Patents

Description

  The present invention relates to a pressure gradient plasma gun for generating an electron beam, and more particularly to improvement of an auxiliary electrode.

  In a vacuum plasma film forming apparatus or the like, a film forming material on a hearth is heated by an electron beam and melted, evaporated or sublimated to form a metal or ceramic thin film on a substrate. One of the plasma guns that generate such an electron beam or plasma is a pressure gradient type plasma gun. As an example of the pressure gradient type plasma gun, in FIG. 6 of Patent Document 1 and paragraph 0002 of the prior art, a high-efficiency discharge with a low voltage and a large current is achieved by adopting an electrode structure composed of a main electrode and an auxiliary electrode. What is aimed at is disclosed. In a plasma film forming apparatus equipped with a pressure gradient type plasma gun, a main electrode is formed by forming a pressure gradient between the cathode region and the film forming chamber so that the pressure in the cathode region is higher than the pressure in the film forming chamber. Since the direct hit of plasma on the auxiliary electrode and the like is alleviated, damage to the main electrode and auxiliary electrode due to the plasma is prevented. As described above, according to the plasma film forming apparatus equipped with the pressure gradient type plasma gun, the main electrode and the auxiliary electrode are prevented from being damaged, so that the desired film forming quality can be secured stably over a long period of time. It is stated that it can be done.

  More specifically, as shown in FIG. 4, a conventional pressure gradient type plasma gun 51 has a cylindrical shape having one end 20b hermetically connected to a base 10 connected to a cathode (not shown) and an opening 21 at the other end 20a. The cathode protection tube 20 is provided. In the cathode protection tube 20, a gas induction tube 52 having a through hole 12 a communicating with the gas source communication hole 10 a of the substrate from the substrate 10 side is provided coaxially with the cathode protection tube toward the opening 21. The tip 52b of the gas guide tube 52 is provided with a disk-shaped main electrode 40 having an opening 40a through which the outer periphery of the tip of the gas guide tube passes, and the main electrode 40 and the opening 21 of the cathode protection tube A discharge space 41 is formed between the two. Further, the tip 52b of the gas guide tube 52 protruding from the opening 40a of the main electrode 40 serves as an auxiliary electrode. From the viewpoints of operating temperature, price, workability, etc., the material of each member is frequently made of molybdenum or tungsten material for the cathode protective tube, tantalum for the gas induction tube, and lanthanum hexaboride for the main electrode.

  The conventional pressure gradient type plasma gun 51 is discharged as follows. As shown in FIG. 5A, immediately after the start of discharge, that is, in a state where the auxiliary electrode 52b and the main electrode 40 are not sufficiently heated, the other end portion 20a of the cathode protective tube 20 closest to the application auxiliary electrode 13 is provided. Plasma 42 is generated by glow discharge. Then, when sufficient electrons are supplied to the space 41 by glow discharge, the tip 52b of the gas induction tube protruding from the opening 40a starts hollow discharge as an auxiliary electrode, and the plasma 43 is generated as shown in FIG. To occur. Furthermore, when several tens of seconds have elapsed from the start of discharge, the temperature of the main electrode 40 rises due to heat radiation from the auxiliary electrode 52b. Then, a sufficient amount of thermionic electrons are emitted from the main electrode 40, and plasma due to thermionic discharge from the main electrode 40 becomes dominant in the plasma discharge as shown in FIG. As a result, a stable high-pressure plasma 46 is generated and drawn into the anode side, and a target such as a film forming material is heated.

  However, in this device, the auxiliary electrode 52b is cylindrical or tubular and penetrates through the opening 40a at the center of the main electrode 40, so that thermionic electrons are not emitted from the center of the main electrode. There was a problem of letting it. Although not described in Patent Document 1, the temperature of the main electrode during the main discharge is close to 2000 ° C., so that the main electrode was exposed to the discharge space during the main electrode discharge as shown in the part surrounded by the ellipse in FIG. There was a problem that the consumption of the auxiliary electrode (tip of the gas introduction pipe) 52b was severe.

  Therefore, in Patent Document 1, the tip of the gas induction tube is retracted, and the tip of the gas introduction tube is separated from the main electrode and the discharge space. As a result, the auxiliary electrode is eliminated. Furthermore, the main electrode was formed into a flat plate shape without a through hole that cuts off the axis of the cathode protective tube at a right angle plane. Further, in order to introduce the gas into the discharge space between the other end of the cathode protective tube and the main electrode, a gas introduction hole is provided between the main electrode and the inner peripheral surface of the cathode protective tube. In addition, in order to replace the auxiliary electrode that disappears due to the retraction of the gas introduction tube, a protrusion that protrudes from the vicinity of the gas introduction hole on the outer edge of the main electrode toward the discharge space is provided and used as an alternative to the auxiliary electrode.

  In Patent Document 2, the tip of the gas introduction tube is retracted, and a filament is provided as an auxiliary electrode, and the filament is heated to actively generate thermoelectrons to increase the discharge sustainability. Further, two main electrodes are provided, a plurality of discharge spaces are provided, the effective area of the main electrode is increased, and the plasma discharge efficiency during the main discharge is improved.

JP 2010-262835 A Japanese Patent No. 4359597

  However, in Patent Document 1, the tip of the gas guide tube is not consumed as compared with the conventional one, but if the projecting portion of the newly provided outer edge of the main electrode is formed into a protruding shape that is easy to discharge, the main power source side becomes hot. Therefore, there has been a new problem that the protrusions are easily consumed. In addition, since the gas introduction port is provided at the outer edge of the main electrode, the shape of the introduction port, the area calculation, and the gas flow in the discharge space become complicated, and there is a possibility that stable gas supply to the discharge space may be difficult. . Further, when the outer edge is worn and the shape changes, the pressure gradient in the discharge space changes greatly, making it difficult to obtain stable discharge conditions.

  On the other hand, since the projection is provided on the outer edge of the main electrode and the central through hole is blocked, the electrode area of the entire main electrode can be increased. However, since the protrusion is the outer edge of the main electrode, the distance from the opening at the other end of the cathode protective tube is longer than the center of the main electrode, so that the function as an auxiliary electrode at the initial stage of discharge is deteriorated. was there.

  In Patent Document 2, the area of the main electrode can be increased. However, since a tungsten filament is added, the structure and control are complicated. Furthermore, there is a problem that a separate power source is required for heating the filament. Further, although it is conceivable to replace the base side of the two main electrodes of Patent Document 2 with that of Patent Document 1, in this case, a filament cannot be attached. Further, there is a problem that the cathode protective tube becomes long and the apparatus becomes large. Furthermore, the above-described problem of Patent Document 1 cannot be solved.

  In view of the above-mentioned problems, an object of the present invention is to provide a pressure gradient type plasma gun that has a simple structure, does not consume a gas induction tube, consumes an alternative auxiliary electrode, and can maintain a stable plasma. In addition, the maintenance cost of the plasma gun is reduced, and at the same time, the operating rate of the expensive plasma vacuum film forming apparatus is improved.

  In the present invention, there is provided a base connected to the cathode, and a cylindrical cathode protective tube having one end hermetically connected to the base and having an opening at the other end. A gas induction tube having a through hole communicating with the gas source communication hole of the base; an auxiliary electrode flat plate that is spaced apart from the gas induction tube and blocks the axis of the cathode protective tube at a right angle plane; and A main electrode having an opening concentric with the opening provided on the opening side of the electrode plate, and a gas penetrating or notching the outer edge of the auxiliary electrode plate By providing a pressure gradient type plasma gun provided with an introduction port, the distance between the auxiliary electrode flat plate and the main electrode being a distance capable of glow discharge between the auxiliary electrode flat plate and the main electrode. Solved the problem.

  That is, the auxiliary electrode flat plate is disposed in the vicinity of the opening of the main electrode, gas is passed from the outer peripheral side of the auxiliary electrode to the main electrode opening, and glow discharge is enabled between the main electrode and the auxiliary electrode flat plate. Accordingly, the inside of the opening of the main electrode, a part of the back surface of the main electrode, and the auxiliary electrode flat plate can be used as an initial glow discharge heating source for heating the main electrode. Furthermore, the inside of the main electrode, the opening of the main electrode, and a part of the back surface of the main electrode can be used as a plasma discharge area during main plasma discharge. The main electrode and auxiliary electrode flat plate and the gas guide tube are separated from each other.

  In order to enable glow discharge between the main electrode and the auxiliary electrode flat plate, the distance between the auxiliary electrode flat plate and the main electrode is not more than twice the opening diameter of the main electrode. 0.3 times or more. This value is a preferable value as a specific example, and is not an absolute condition that enables glow discharge. According to a third aspect of the invention, the heat resistance temperature of the auxiliary electrode flat plate material is lower than the heat resistance temperature of the main electrode material. As the material of the main electrode, lanthanum hexaboride (LaB6) is generally used. However, since the auxiliary electrode flat plate of the present invention has few parts exposed to high temperature, the same tantalum as that of the conventional gas induction tube may be used. Further, since the gas induction tube does not need to serve as an auxiliary electrode, it may be made of a material such as molybdenum or tungsten similar to the cathode protective tube.

  In addition, since the overall length of the gas induction tube is shorter than that of the conventional one, it is better to use a tube whose inner diameter is smaller than that of the conventional one in order to obtain a pressure suitable for glow discharge. Furthermore, the gas induction tube does not need to emit thermal electrons. Therefore, in the invention described in claim 4, the gas induction tube is made of a ceramic material. According to a fifth aspect of the present invention, a pressure gradient plasma gun is provided in which a protrusion is provided in the center of the auxiliary electrode plate toward the main electrode plate. Providing the protrusions facilitates the generation of initial glow discharge. In the invention described in claim 6, the shape of the protrusion is a conical shape having the axis as an axis.

  Further, in the invention according to claim 7, the auxiliary electrode flat plate has a shape in which a part of the disk is cut out at a plurality of positions, and an outer edge portion of the disk is fixed to the inner peripheral surface of the cathode protective tube, A pressure gradient type plasma gun in which the gas inlet is formed by the notched portion and the inner peripheral surface of the cathode protective tube. The gas inlet may be a drill hole or the like, but has a notch shape with less generation of cutting waste.

  Furthermore, in the invention according to claim 8, the auxiliary electrode flat plate and the gas introduction port are integrally molded, and a plurality of circumferential positions of the outer edge portion of the auxiliary electrode flat plate are bent and extended to the main electrode side, A pressure gradient type in which the end of the extended portion of the auxiliary electrode flat plate is in contact with the main electrode and is positioned and fixed in the axial direction, and the gas inlet is formed by the extended portion and the inner peripheral surface of the cathode protective tube A plasma gun was used. That is, the outer edge of the auxiliary electrode flat plate was bent to form the positioning and the gas inlet at the same time.

  In the present invention, an auxiliary electrode flat plate is disposed close to the opening of the main electrode, gas is passed from the outer peripheral side of the auxiliary electrode to the main electrode opening, a part of the main electrode opening and a part of the back surface of the main electrode, the auxiliary electrode flat plate Is used as the initial glow discharge heating source, the main electrode, the inside of the opening of the main electrode, and a part of the back surface of the main electrode as the plasma discharge area, thereby providing a pressure gradient type plasma gun with good discharge efficiency. Further, since the plasma discharge area is increased, the temperature of the main electrode is lowered, the consumption time of the main electrode can be extended, and the life is prolonged.

  Further, since the tip of the gas guide tube is separated without protruding from the opening of the main electrode, there is no influence of high heat by the main electrode, and the tip of the gas guide tube is not damaged. Furthermore, there is no heat escape through the gas induction tube. Since there is no heat escape from the gas induction tube, it is possible to quickly reach a predetermined temperature, and the effect of shortening the plasma ignition time can be obtained. In addition, since the gas that flows stably from the outer edge of the auxiliary electrode flat plate toward the center can be introduced into the opening, the plasma becomes more stable.

  Further, since the auxiliary electrode flat plate is spaced apart from the main electrode and recedes, the influence of high heat by the main electrode is small, so that the consumption of the auxiliary electrode flat plate is also small. Thus, according to the present invention, stable plasma can be sustained. Further, most of the consumables are main electrodes, and it is possible to obtain a longer life, and it is possible to reduce the running cost by extending the inspection and replacement cycle of the production equipment. In order to further enhance this effect, it is better to increase the thickness of the main electrode, and it is better to optimize the distance between the through hole and the auxiliary electrode plate so that the hollow discharge is maintained under the set pressure condition.

    In addition, in the thing of patent document 1, since an auxiliary electrode is lost and only the main electrode was made into the flat plate without an opening, the inside of opening of a main electrode like this invention and a part of back surface of a main electrode are used as a thermoelectron supply source. Therefore, the effective discharge area as in the present invention cannot be increased. Further, even if the base side of the two main electrodes of Patent Document 2 is an electrode flat plate as in Patent Document 1, the problem that the length of the cathode protective tube is long and the device becomes large is not solved because the distance between the electrodes is wide. Further, the same effect can be obtained without using a plurality of expensive main electrodes such as lanthanum hexaboride.

  In the invention described in claim 2, since the distance between the auxiliary electrode flat plate and the main electrode is set to be not more than twice the opening diameter of the main electrode and not less than 0.3 times to facilitate the occurrence of glow discharge, the rise to the predetermined temperature is quick. Become. In the invention described in claim 3, since the auxiliary electrode flat plate material is tantalum (Ta) or the like, and the material is lower than the heat resistant temperature such as lanthanum hexaboride which is the material of the main electrode, the cost is reduced. Furthermore, since there is no need for the gas induction tube to emit thermoelectrons, it is possible to adopt a heat-resistant material such as ceramic in addition to molybdenum (Mo) and tungsten (W) as the material of the gas induction tube. A long service life can be achieved at a low cost (claim 4).

  Furthermore, in the invention described in claim 5, since the projection is provided at the center of the auxiliary electrode plate to facilitate the generation of the initial glow discharge, the predetermined temperature can be reached stably and early. In the invention according to claim 6, since the projection shape is a conical shape, it is possible to further easily induce the discharge.

  Further, in the invention described in claim 7, the gas inlet of the auxiliary electrode flat plate has a shape in which the generation of cutting waste or the like obtained by cutting a part of the disk is small. Since the outer edge of the electrode flat plate is bent and the auxiliary electrode flat plate and the gas inlet are integrally formed, the cost is low and the environment is friendly.

(A) of a pressure gradient type | mold plasma gun in embodiment of this invention is sectional drawing, (b) is a perspective view which sees through the inside. FIG. 4A is a partial sectional view of a plasma discharge state from an electrode of a pressure gradient plasma gun according to the present invention, FIG. (A) of the pressure gradient type | mold plasma gun in other embodiment of this invention is sectional drawing, (b) is a perspective view which sees through the inside. (A) of the conventional pressure gradient type plasma gun is sectional drawing, (b) is a perspective view which sees through the inside. (A) which shows the plasma emission state from the electrode of the conventional pressure gradient type | mold plasma gun is immediately after application, (b) is a transition state, (c) is partial explanatory drawing of a main discharge state. It is a drawing substitute photograph which shows the damage state of the auxiliary electrode tube of the conventional pressure gradient type plasma gun.

  Embodiments of the present invention will be described with reference to the drawings. In the figure, only main components of the pressure gradient type plasma gun are extracted and schematically shown, and other components are omitted. The same reference numerals are given to the same components as those described in the conventional description, and a part or all of the description is omitted. As shown in FIGS. 1A and 1B, a pressure gradient type plasma gun 1 according to an embodiment of the present invention includes a base 10 connected to a cathode (not shown) and one end of the base hermetically connected. A cylindrical cathode protection tube 20 having an opening 21 at 20a, and a glass tube 11 surrounding the cathode protection tube and hermetically connected at one end and having a gun opening 11a at the other end. Further, an electromagnetic coil (not shown), a permanent magnet or the like (not shown) is disposed in the gun opening 11a of the glass tube so that plasma generated by the plasma gun 1 can be irradiated to a target or a substrate in the film forming container.

  A support member 22 is fitted into the base body side 20 b in the cathode protective tube 20. The support member end face side 22 a is fitted and fixed to the base 10 side, and the support member 22 holds the cathode protective tube 20 with respect to the base 10. The central through hole 22 b of the support member 22 communicates with a gas source communication hole 10 a that communicates with a gas source (not shown) (such as an argon gas cylinder) provided in the base 10. In addition, one end (base side) 12 c of the tubular gas guide tube 12 is inserted into the central through hole 22 b of the support member 22, and the other end (tip) 12 b of the gas introduction tube is held by the support partition plate 23. The support partition plate 23 is fixed to the middle 20c in the cathode protective tube with an outer peripheral edge 23a. A support hole 23b is opened in the center of the support partition plate 23 so that the tip 12b of the gas introduction pipe 12 protrudes or has a icicle surface.

  An auxiliary electrode flat plate 30 is provided that is spaced apart from the distal end 12b of the gas induction tube 12 and blocks the axis of the cathode protective tube 20 at a right angle plane. On the outer edge of the auxiliary electrode flat plate 30, four arc-shaped outer edge portions 30a having the same diameter as the inner peripheral surface 20d of the cathode protective tube and four notched portions (notched portions) 30b are provided alternately. Yes. A gas introduction port 35 is formed by the inner peripheral surface 20d of the cathode protective tube and the cutout portion 30b. The auxiliary electrode flat plate 30 can be easily manufactured by cutting or shaping the four corners of a square tantalum plate in accordance with the inner peripheral surface of the cathode protective tube. An annular member 24 is provided adjacent to the auxiliary electrode flat plate 30 on the opening 21 side of the cathode protection tube 20 to be fitted to the inner peripheral surface 20d of the cathode protection tube.

  Adjacent to the annular member 24, the main electrode 40 is provided on the opening 21 side of the cathode protective tube 20. The shape of the main electrode is a disk shape having a through hole 40a as in the conventional case. A discharge space 41 is formed between the main electrode 40 and the opening 21 of the cathode protection tube 20. Further, the distance between the auxiliary electrode flat plate 30 and the main electrode 40 indicated by the symbol d in FIG. 2B is a distance that allows glow discharge between the auxiliary electrode flat plate and the main electrode. This distance is maintained at a predetermined distance by sandwiching the annular member 24 between the auxiliary electrode flat plate and the main electrode. The cathode protective tube 20, the opening 21, the gas guide tube 12, the support hole 23b of the support partition plate 23, the opening 40a of the main electrode 40, and the like are substantially concentric (coaxial).

  The base 10, the cathode protection tube 20, the gas induction tube 21, the auxiliary electrode flat plate 30, the main electrode 40 and the like are electrically connected to a negative electrode of a direct current power source (not shown) directly or via appropriate wiring. In addition, the outside is airtight. Further, it is preferable that the inside and outside of the cathode protection tube 20 excluding the opening 21 and the base 10, the inside of the cathode protection tube 20 and the outer periphery of the main electrode 40 or the outer periphery of the annular member 24, and the outer periphery of the support partition plate 23 are airtight. . The material of the main electrode 40 is lanthanum hexaboride (LaB6), which has a high heat resistant temperature and a large electron emission power. Further, the auxiliary electrode flat plate is made of tantalum (Ta) that easily generates glow discharge at a lower temperature than lanthanum hexaboride. The cathode protective tube is made of molybdenum (Mo) or tungsten (W) as in the conventional case. The gas induction tube need not be tantalum, but may be molybdenum or tungsten, or ceramics.

  The plasma when the pressure gradient type plasma gun 1 in the embodiment of the present invention is used in a plasma film forming apparatus will be described. As shown in FIG. 2A, glow discharge 42 is started from the other end 20a of the cathode protective tube 20 in accordance with Paschen's law as in the prior art. When a sufficient amount of electrons are supplied by glow discharge, as shown in FIG. 2 (b), instead of hollow discharge using the tip of the gas induction tube of the conventional plasma film forming apparatus as an auxiliary electrode, auxiliary A glow discharge (auxiliary discharge) 43 is generated between the electrode flat plate 30 and the main electrode 40. This is presumed that the gap d between the main electrode and the auxiliary electrode flat plate forms a Grimm-type electrode structure, and auxiliary discharge is started. The main electrode 40 is heated by this auxiliary discharge.

  Next, when the main electrode 40 is heated, thermoelectrons are emitted, heating is also accelerated, and main discharge by the main electrode 40 is started at a high temperature. Then, as shown in FIG. 2C, the supplied LUGON (Ar) gas 44 is supplied to the pressure gradient type plasma gun 1 (inside the cathode protective tube 20) with the gas induction tube 12, the support partition plate 23 and the auxiliary. Between the electrode flat plate 30, the gas inlet 35 on the outer edge of the auxiliary electrode flat plate, between the auxiliary electrode flat plate 30 and the main electrode 40, the opening 40 a of the main electrode 40, the discharge chamber 41, and the other end 20 a of the cathode protective tube. Passing through the opening 21 sequentially, it is introduced into the film forming apparatus, and accordingly, the plasma 45 is emitted toward a film forming chamber (not shown) provided in the plasma film forming apparatus.

  At this time, if the tip of the conventional gas guide tube is used as a part of the auxiliary electrode, the opening 40a of the main electrode 40 is closed. On the other hand, in the present embodiment, heat is also generated from the inner periphery of the opening 40a and a part 40c on the back side of the main electrode 40 in addition to the annular region 40b of the main electrode 40 by the opening 40a of the main electrode. Electrons are emitted. Thereby, plasma is emitted with higher efficiency than the area of the annular region 40b of the conventional main electrode. Further, the tip 12b of the gas induction tube 12 is not damaged, and the auxiliary electrode flat plate 30 is also separated from the main electrode 40. Therefore, the damage is small, and the flow path of the argon gas and the change in the discharge area are small and stable. Plasma can be supplied.

  Next, another embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 3, in another embodiment of the present invention, an auxiliary electrode flat plate is integrated, and a protrusion is provided at the center, and the other configurations are the same except for the auxiliary electrode flat plate and the annular member. is there. Configurations similar to those of the conventional example and the above-described embodiment are denoted by the same reference numerals, and a part or all of the description is omitted. As shown in FIG. 3, the pressure gradient type plasma gun 2 according to another embodiment of the present invention has a conical protrusion toward the opening coaxially with the opening 40a of the main electrode 40 at the center of the auxiliary electrode flat plate 31. A part 32 is provided. The height of the protrusion is preferably shorter than the gap between the auxiliary electrode flat plate and the main electrode (reference symbol d in FIG. 2B). Thereby, the influence of the plasma discharge at the high temperature of the main electrode 40 on the protrusion 32 is reduced.

  The outer edge portion 31a of the auxiliary electrode flat plate 31 has an outer diameter substantially the same as the inner diameter of the inner peripheral surface 20d of the cathode protective tube 20, and the outer edge portion is fixed to the inner peripheral surface of the cathode protective tube. Four portions between the outer edge portions 31a are bent to the main electrode side to form extended portions 31b. Further, a gas introduction port 35 is formed by the bent (extending portion) 31b and the inner peripheral surface 20d of the cathode protective tube. The bent (extending portion) end 31c is brought into contact with the main electrode rear surface 40c, and the distance between the main electrode 40 and the auxiliary electrode flat plate 30 (symbol d in FIG. 2B) is maintained instead of the annular member 24 described above. Thus, the positioning is fixed in the axial direction.

  In addition, the auxiliary electrode flat plate 31 may be formed by making eight cuts in a circular outer edge portion and bending four portions every other portion to the main electrode side, or integrally molding, casting, or the like. In addition, a main electrode pressing ring 25 is disposed in order to fix the main electrode 40 and prevent gas introduction and hollow discharge from the periphery of the main electrode. When the main electrode holding ring 25 is not installed, the outer periphery of the main electrode is worn due to discharge due to leakage of argon gas. The wear on the outer periphery of the main electrode greatly changes the pressure gradient, which is not preferable for obtaining a stable long-life discharge that does not change the discharge conditions.

  In such another embodiment, the discharge is performed in the same manner as in FIG. 2, but further, the auxiliary discharge transition time is shortened by the addition of the protrusion of the central protrusion 32 of the auxiliary electrode flat plate 30, or the effective of the auxiliary electrode is reduced. By increasing the surface area, the main electrode can be efficiently heated during auxiliary discharge. Thereby, it becomes possible to suppress the power consumption when heating the main electrode 40, and to shorten the waiting time until the plasma emission starts.

1, 2 Pressure gradient type plasma gun.
DESCRIPTION OF SYMBOLS 10 Base | substrate 10a Gas source communication hole 12 of base | substrate Gas induction pipe | tube 12a Through hole 20 Cathode protection pipe 20a Other end part 20b One end 20d Cathode protection pipe inner peripheral surface 21 Opening part 30, 31 Auxiliary electrode flat plate 30a, 31a Outer edge part 30b Notch part (Notched part)
31b Folding extension part 31c Bending extension part end 32 Projection part 35 Gas introduction port 40 Main electrode 40a (main electrode) opening

Claims (8)

  A base connected to the cathode, and a cylindrical cathode protective tube having one end hermetically connected to the base and having an opening at the other end, and in the cathode protective tube from the substrate side, A gas induction tube having a through hole communicating with the gas source communication hole; an auxiliary electrode flat plate that is spaced apart from the gas induction tube and blocks the axis of the cathode protective tube at a right angle plane; and the opening of the auxiliary electrode flat plate A main electrode having an opening concentric with the opening, and a gas introduction port penetrating or notching the outer edge is provided at the outer edge of the auxiliary electrode flat plate. The pressure gradient plasma gun is characterized in that the distance between the auxiliary electrode flat plate and the main electrode is a distance capable of glow discharge between the auxiliary electrode flat plate and the main electrode.   2. The pressure gradient plasma gun according to claim 1, wherein a distance between the auxiliary electrode flat plate and the main electrode is set to be not more than twice the opening diameter of the main electrode and not less than 0.3 times. .   The pressure gradient type plasma gun according to claim 1 or 2, wherein the heat resistant temperature of the auxiliary electrode flat plate material is lower than the heat resistant temperature of the material of the main electrode.   4. The pressure gradient type plasma gun according to claim 1, wherein the gas induction tube is made of ceramics.   5. The pressure gradient plasma gun according to claim 1, wherein a projection is provided in the center of the auxiliary electrode plate toward the main electrode plate.   6. The pressure gradient plasma gun according to claim 5, wherein the protruding shape is a conical shape with the axis as an axis.   The auxiliary electrode flat plate has a shape in which a part of a disk is cut out at a plurality of positions, and an outer edge portion of the disk is fixed to the inner peripheral surface of the cathode protective tube, and the notched portion and the inner peripheral surface of the cathode protective tube 7. The pressure gradient plasma gun according to claim 5, wherein the gas inlet is formed.   The auxiliary electrode flat plate and the gas introduction port are integrally formed, a plurality of circumferential positions of the outer edge portion of the auxiliary electrode flat plate are bent and extended toward the main electrode side, and the extension portion end of the auxiliary electrode flat plate is The pressure gradient according to claim 5 or 6, wherein the gas introduction port is formed by the extension part and the inner peripheral surface of the cathode protective tube, being in contact with the main electrode and positioned and fixed in the axial direction. Type plasma gun.