JP2009021220A - Plasma processing apparatus, antenna, and method of using plasma processing apparatus - Google Patents

Abstract

An electric field is prevented from concentrating on the surface of a metal electrode.
A plasma processing apparatus includes a processing container, a microwave source that outputs microwaves, an inner conductor of a coaxial tube that transmits microwaves, and a through hole 305a, and transmits the inner conductor. The dielectric plate 305 that transmits the emitted microwave to the inside of the processing container 100 and the inner conductor 315a through the through hole 305a, and at least a part thereof is adjacent to the substrate side surface of the dielectric plate 305. And a metal electrode 310 exposed from the surface of the dielectric plate 305 on the substrate side. One of the exposed surfaces of the metal electrode 310 is covered with a dielectric cover 320.
[Selection] Figure 6

Description

  The present invention relates to a plasma processing apparatus that plasmas a target object by exciting a gas with electromagnetic waves, and more particularly to a plasma processing apparatus that includes an antenna that supplies low-frequency electromagnetic waves into a processing container.

  Conventionally, a method for introducing electromagnetic waves into a plasma processing chamber using a waveguide or a coaxial tube has been developed (see, for example, Patent Document 1). According to Patent Document 1, a lower portion of a cylindrical central conductor of a coaxial tube is fitted into a circular through hole formed at the center of a dielectric disk, and an excitation metal is placed in the lower end of the central conductor. A cap is inserted. A protective cap is attached to the bottom surface and the outer peripheral surface of the cap so that these surfaces are not directly exposed to the plasma generation chamber. The protective cap prevents the metal cap from being damaged due to the concentration of the electric field on the metal cap due to the plasma generated in the plasma generation chamber.

JP-A-10-144497

  However, when covering the entire metal cap with the protective cap, if one surface such as the bottom surface or the outer peripheral surface of the metal cap is brought into close contact with the protective cap, a gap is generated on the other surface of the metal cap, and abnormal discharge occurs in the gap. May occur and the plasma may become non-uniform and unstable. On the other hand, if any surface of the metal cap is brought into close contact with the protective cap to increase the processing accuracy so as not to create a gap, the cost increases.

  In order to solve the above-described problem, according to an aspect of the present invention, a plasma processing apparatus that plasmas a target object by exciting a gas with an electromagnetic wave, a processing container, an electromagnetic wave source that outputs the electromagnetic wave, A conductor rod for transmitting electromagnetic waves output from the electromagnetic wave source, a dielectric plate in which a through-hole is formed, and transmits the electromagnetic waves transmitted through the conductor rod to be emitted into the processing container; and A metal electrode that is connected to the conductor rod through the formed through hole and is exposed from the surface of the dielectric plate on the workpiece side in a state where at least a part thereof is adjacent to the surface of the dielectric plate on the workpiece side And a plasma processing apparatus in which a part of the exposed surface of the metal electrode is covered with a dielectric cover.

  According to this configuration, a part of the exposed surface of the metal electrode is covered with the dielectric cover. According to this, the electric field in the vicinity of the metal electrode can be weakened, and the uniformity of the plasma can be improved. At this time, for machining accuracy, if there are two or more processed surfaces, a gap is generated, and abnormal discharge may occur in the gap.

  However, according to this configuration, one surface of the exposed portion of the metal electrode is covered with the dielectric cover. Thus, when only one surface such as the bottom surface and the outer peripheral surface of the metal electrode is covered with the dielectric cover among the exposed portions of the metal electrode, the metal electrode and the dielectric cover can be brought into close contact with each other. Thereby, since a gap does not occur between the metal electrode and the dielectric cover, abnormal discharge can be prevented and plasma can be generated uniformly and stably. Moreover, since high-precision machining is not necessary, the cost can be suppressed.

  In order to solve the above problems, according to another aspect of the present invention, there is provided a plasma processing apparatus for plasma processing a target object by exciting a gas with an electromagnetic wave, the processing container and an electromagnetic wave for outputting the electromagnetic wave. Source, a conductor rod for transmitting the electromagnetic wave output from the electromagnetic wave source, a dielectric plate in which a through hole is formed, and transmits the electromagnetic wave transmitted through the conductor rod to be emitted into the processing container, and the dielectric It is connected to the conductor rod through a through hole formed in the body plate, and is exposed from the surface of the dielectric plate on the workpiece side in a state where at least a part is adjacent to the surface of the dielectric plate on the workpiece side. A plasma processing apparatus is provided in which the exposed surface of the metal electrode does not have a surface substantially parallel to the object to be processed.

  As shown in FIG. 7, the inventors of the present invention performed a surface parallel to the object to be processed (surface C) among the metal electrodes exposed on the object side surface of the dielectric plate as shown in FIG. 7. I found that the electric field strength increased.

  Therefore, by forming the exposed surface of the metal electrode so as not to have a surface substantially parallel to the object to be processed, the electric field in the vicinity of the metal electrode can be weakened and the plasma uniformity can be improved. For example, the exposed surface of the metal electrode may be formed in a substantially conical shape or a substantially hemispherical shape.

  At this time, the exposed portion of the metal electrode may be provided adjacent to a part or all of the surface of the dielectric plate on the object side. According to this, the dielectric plate can be firmly held by the metal electrode.

  Further, at least a surface of the exposed portion of the metal electrode that is substantially parallel to the treatment body may be covered with a dielectric cover. The electric field is difficult to concentrate on the surface of the dielectric cover. Therefore, by covering the exposed part of the metal electrode with a dielectric cover, it is possible to avoid the concentration of the electric field on the surface of the metal electrode near the feeding point and the generation of high density plasma near the metal electrode. Thus, uniform plasma can be generated.

  The dielectric cover may be formed of a porous ceramic. According to this, the gas can be introduced into the processing container by flowing the gas between the pores of the dielectric cover formed of the porous ceramic.

  The exposed surfaces of the metal electrode and the dielectric cover may be formed in a substantially conical shape. The tip of the dielectric cover may be formed flat. The height of the dielectric cover in the direction perpendicular to the object to be processed may be within 10 mm. According to this, the electric field is not concentrated on the surface of the dielectric cover, and uniform plasma can be generated and metal contamination can be effectively avoided.

  The through hole of the dielectric plate may be provided at substantially the center of the dielectric plate. According to this, a dielectric plate can be hold | maintained with sufficient balance using a metal electrode. Further, electromagnetic waves can be uniformly supplied from the coaxial tube through the dielectric plate into the processing container.

The surface of the metal electrode may be covered with a protective film. For example, the surface of the metal electrode may be protected by a protective film of yttria (Y ₂ O ₃ ), alumina (Al ₂ O ₃ ), or Teflon (registered trademark) having high corrosion resistance. Thereby, it can avoid that a metal electrode is corroded by F-type gas (fluorine radical), chlorine-type gas (chlorine radical), etc. FIG.

  A gas introduction path for flowing gas is formed inside the coaxial pipe, and the metal electrode communicates with a gas introduction path formed inside the coaxial pipe, and the gas flowing through the gas introduction path is treated as described above. A gas passage to be introduced into the container may be formed.

  According to this, gas is introduce | transduced in a processing container from the gas channel provided in the metal electrode. Since metal does not transmit electromagnetic waves, gas does not excite in the gas passage in the metal electrode. Thereby, it is possible to avoid the generation of plasma in the metal electrode.

  The gas passage formed in the metal electrode may be formed so that the gas is introduced in a direction substantially parallel to the object to be processed, and the gas passage in a direction substantially perpendicular to the object to be processed. May be formed so that a gas is introduced, or a gas may be introduced radially.

  The gas may be introduced directly into the processing container from a gas passage formed in the metal electrode. Further, the gas may be introduced into the processing container through a dielectric cover formed of porous ceramic from the gas passage. In particular, when the gas is supplied from a porous ceramic, the gas is gradually released from the surface of the porous ceramic in a state where it is slowed down to some extent while flowing between the pores of the porous ceramic. The Thereby, it is possible to prevent the gas from being diffused unnecessarily in the processing container, and as a result, it is possible to generate a desired plasma without excessively dissociating the gas.

  The dielectric plate may be made of alumina.

  The dielectric plate may be formed from a plurality of dielectric plates, and a plurality of the metal electrodes may be provided corresponding to the plurality of dielectric plates. According to this, since the dielectric plate is composed of a plurality of dielectric plates, it is easy to perform maintenance such as replacement of parts, and provides a plasma processing apparatus with high expandability according to the increase in the area of the object to be processed. be able to.

  In addition, each dielectric plate of the plurality of dielectric plates may be formed so that a surface on the object to be processed side has a substantially rectangular shape. Each dielectric plate of the plurality of dielectric plates may be formed so that the surface on the object to be processed side is substantially square. According to this, since each dielectric plate has a symmetrical shape, electromagnetic waves are uniformly emitted from a plurality of dielectric plates arranged over the entire ceiling surface. As a result, plasma can be generated more uniformly below the dielectric plate.

  The electromagnetic wave source may output an electromagnetic wave having a frequency of 1 GHz or less. According to this, the cut-off density can be lowered, the process window can be widened, and various processes can be realized with one apparatus.

  During the process, the side surface of the dielectric plate may be in contact with the plasma. If the dielectric plate and another member are in contact with each other around the dielectric plate, a gap is generated, and there is a possibility that abnormal discharge may occur due to plasma entering the gap. To eliminate the gap, high-precision machining is required, but this leads to high costs. However, according to this, the side surface of the dielectric plate is in contact with the plasma. Therefore, no gap is generated around the dielectric plate, and high-precision machining is not required and costs can be reduced.

  In order to solve the above problem, according to another aspect of the present invention, a conductor rod for transmitting electromagnetic waves and a through hole are formed, and the electromagnetic waves transmitted through the conductor rod are transmitted to transmit the inside of the processing vessel. The dielectric plate is connected to the conductor bar through a through hole formed in the dielectric plate, and at least a part of the dielectric plate is adjacent to the surface of the dielectric plate to be processed. There is provided an antenna comprising: a metal electrode exposed from a surface of the body plate on the object to be processed side, wherein one of the exposed surfaces of the metal electrode is covered with a dielectric cover.

  In order to solve the above problem, according to another aspect of the present invention, a conductor rod for transmitting electromagnetic waves and a through hole are formed, and the electromagnetic waves transmitted through the conductor rod are transmitted to transmit the inside of the processing vessel. The dielectric plate is connected to the conductor bar through a through hole formed in the dielectric plate, and at least a part of the dielectric plate is adjacent to the surface of the dielectric plate to be processed. There is provided an antenna having a metal electrode exposed from a surface of the body plate on the side of the object to be processed, and the exposed surface of the metal electrode does not have a surface substantially parallel to the object to be processed.

  In order to solve the above problem, according to another aspect of the present invention, an electromagnetic wave having a frequency of 1 GHz or less is output from an electromagnetic wave source, the electromagnetic wave is transmitted to a conductor rod, and a through-hole formed in a dielectric plate A metal electrode that is connected to the conductor rod through a hole and is exposed from the surface of the dielectric plate on the workpiece side with at least a portion adjacent to the surface of the dielectric plate on the workpiece side. The dielectric plate held on the inner wall transmits the electromagnetic wave transmitted through the conductor rod and emits it into the processing vessel, and the emitted electromagnetic wave excites the processing gas introduced into the processing vessel to cover the dielectric plate. A method of using a plasma processing apparatus for performing a desired plasma processing on a processing body is provided.

  In order to solve the above problem, according to another aspect of the present invention, an electromagnetic wave having a frequency of 1 GHz or less is output from an electromagnetic wave source, the electromagnetic wave is transmitted to a conductor rod, and a through-hole formed in a dielectric plate A metal electrode that is connected to the conductor rod through a hole and is exposed from the surface of the dielectric plate on the workpiece side with at least a portion adjacent to the surface of the dielectric plate on the workpiece side. The dielectric plate held on the inner wall transmits the electromagnetic wave transmitted through the conductor rod and emits it into the processing vessel, and the emitted electromagnetic wave excites the cleaning gas introduced into the processing vessel to generate plasma. A plasma processing apparatus cleaning method for cleaning a processing apparatus is provided.

  According to this, for example, by using an electromagnetic wave with a frequency of 1 GHz or less, a surface wave does not spread in a single gas state with a certain level of power of an electromagnetic wave with a frequency of 2.45 GHz, and a uniform and stable plasma can be excited. Even if there was no F-based single gas, uniform and stable plasma can be excited. Thereby, the cleaning gas is excited using the power of practical electromagnetic waves, and the inside of the plasma processing apparatus can be cleaned with the plasma generated thereby.

BEST MODE FOR CARRYING OUT THE INVENTION

(First embodiment)
First, referring to the accompanying drawings, first, with respect to the plasma processing apparatus according to the first embodiment of the present invention, FIG. This will be described with reference to FIG. 2 showing the ceiling surface of the processing container. In the following description and the accompanying drawings, components having the same configuration and function are denoted by the same reference numerals, and redundant description is omitted.

(Configuration of plasma processing equipment)
The plasma processing apparatus 10 includes a processing container 100 for plasma processing a glass substrate (hereinafter referred to as “substrate G”). The processing container 100 includes a container body 200 and a lid body 300. The container body 200 has a bottomed cubic shape with an upper portion opened, and the opening is closed by a lid 300. An O-ring 205 is provided on the contact surface between the container main body 200 and the lid body 300, whereby the container main body 200 and the lid body 300 are sealed, and the processing chamber U is formed. The container body 200 and the lid body 300 are made of, for example, a metal such as aluminum and are electrically grounded.

  A susceptor 105 (stage) for placing the substrate G is provided inside the processing container 100. The susceptor 105 is made of, for example, aluminum nitride, and a power feeding unit 110 and a heater 115 are provided therein.

  A high frequency power supply 125 is connected to the power supply unit 110 via a matching unit 120 (for example, a capacitor). Further, a high-voltage DC power supply 135 is connected to the power feeding unit 110 via a coil 130. The matching unit 120, the high frequency power source 125, the coil 130, and the high voltage DC power source 135 are provided outside the processing container 100. The high frequency power supply 125 and the high voltage DC power supply 135 are grounded.

  The power supply unit 110 applies a predetermined bias voltage to the inside of the processing container 100 by the high frequency power output from the high frequency power source 125. The power feeding unit 110 is configured to electrostatically attract the substrate G with a DC voltage output from the high-voltage DC power supply 135.

  An AC power supply 140 provided outside the processing container 100 is connected to the heater 115, and the substrate G is held at a predetermined temperature by an AC voltage output from the AC power supply 140. The susceptor 105 is supported by a support body 145, and a baffle plate 150 for controlling the gas flow in the processing chamber U to a preferable state is provided around the susceptor 105.

  A gas discharge pipe 155 is provided at the bottom of the processing container 100, and the gas in the processing container 100 is discharged from the gas discharge pipe 155 using a vacuum pump (not shown) provided outside the processing container 100. As a result, the processing chamber U is depressurized to a desired degree of vacuum.

The lid 300 is provided with a plurality of dielectric plates 305, a plurality of metal electrodes 310, and a plurality of coaxial pipe inner conductors 315a. Referring to FIG. 2, the dielectric plate 305 is formed of alumina (Al ₂ O ₃ ) and a substantially square plate of 148 mm × 148 mm has an in-tube wavelength of the branched coaxial tube 640 of λg (328 mm at 915 MHz). , Λg / 2 are arranged in the vertical and horizontal directions at equal intervals of an integral multiple of 1 (here, 1 time). Accordingly, 224 (= 14 × 16) dielectric plates 305 are evenly arranged on the ceiling surface of the processing container 100 of 2277.4 mm × 2605 mm.

  Thus, since the dielectric plate 305 has a shape with good symmetry, uniform plasma is likely to be generated in one dielectric plate 305. In addition, by arranging the plurality of dielectric plates 305 at equal intervals of an integral multiple of λg / 2, uniform plasma can be generated when electromagnetic waves are introduced using the inner conductor 315a of the coaxial tube.

  Returning to FIG. 1 again, the groove 300a shown in FIG. 1 is cut in the metal surface of the lid 300 to suppress the propagation of the conductor surface wave. The conductor surface wave is a wave propagating between the metal surface and the plasma.

  A metal electrode 310 is provided at the tip of the internal conductor 315 a penetrating the dielectric plate 305 so as to be exposed to the substrate G side, and the dielectric plate 305 is held by the internal conductor 315 a and the metal electrode 310. Yes. A dielectric cover 320 is provided on the surface of the metal electrode 310 on the substrate side to prevent concentration of the electric field.

  Further description will be continued with reference to FIG. 3 showing the cross section A-A′-A of FIG. 2. The coaxial tube 315 includes a cylindrical inner conductor (shaft portion) 315a and an outer conductor 315b, and is formed of metal (preferably copper). Between the lid 300 and the internal conductor 315a, a ring-shaped dielectric 410 through which the internal conductor 315a passes is provided at the center. O-rings 415a and 415b are provided on the inner peripheral surface and the outer peripheral surface of the ring-shaped dielectric 410, whereby the inside of the processing chamber U is vacuum-sealed.

  The inner conductor 315a protrudes outside the processing container 100 through the lid portion 300d. The internal conductor 315a is lifted toward the outside of the processing container 100 by the fixing mechanism 500 including the connecting portion 510, the spring member 515, and the short-circuit portion 520 using the elastic force of the spring member 515. Note that the lid portion 300d is an upper surface of the lid body 300, and is a portion integrated with the lid body 300 and the external conductor 315b in the vicinity of the lifted portion of the internal conductor 315a.

  A short-circuit portion 520 is provided at a penetrating portion of the internal conductor 315a, and the internal conductor 315a and the lid portion 300d of the coaxial tube 315 are electrically short-circuited. The short-circuit portion 520 includes a shield spiral, and is provided so that the internal conductor 315a can slide up and down. Note that a metal brush can be used for the short-circuit portion 520.

  As described above, by providing the short-circuit portion 520, heat flowing from the plasma to the metal electrode 310 can be efficiently released to the lid through the internal conductor 315a and the short-circuit portion, so that the heating of the internal conductor 315a is suppressed and the internal conductor is suppressed. Deterioration of the O-rings 415a and 415b adjacent to 315a can be prevented. Moreover, since the short circuit part 520 prevents the microwave from being transmitted to the spring member 515 through the internal conductor 315a, abnormal discharge and power loss around the spring member 515 do not occur. Further, the short-circuit portion 520 can prevent the inner conductor 315a from shaking and can be held firmly.

  The short-circuit portion 520 is vacuum-sealed with an O-ring (not shown) between the lid portion 300d and the internal conductor 315a and between a dielectric 615 and a lid portion 300d, which will be described later, in the lid portion 300d. By filling the space with an inert gas, impurities in the atmosphere can be prevented from entering the processing chamber.

  The refrigerant supply source 700 of FIG. 1 is connected to the refrigerant pipe 705, and the refrigerant supplied from the refrigerant supply source 700 circulates in the refrigerant pipe 705 and returns to the refrigerant supply source 700, whereby the processing container 100 is removed. The desired temperature is maintained. The gas supply source 800 is introduced into the processing chamber through the gas line 805 from the gas flow path in the inner conductor 315a shown in FIG.

A microwave having a power of 120 kW (= 60 kW × 2 (2 W / cm ² )) output from two microwave sources 900 is converted into a branched waveguide 905 (see FIG. 4), eight coaxial waveguide conversions. 7, eight coaxial pipes 620, seven coaxial pipes 600 connected to eight branch coaxial pipes 640 (see FIG. 2) located parallel to the back direction of FIG. 1, and branch plates 610 (see FIG. 5). And transmitted through the coaxial tube 315 and transmitted through the plurality of dielectric plates 305 to be supplied into the processing chamber. The microwave released into the processing chamber U excites the processing gas supplied from the gas supply source 800, and a desired plasma processing is performed on the substrate G using the plasma generated thereby.

(Holding the dielectric plate with metal electrodes)
Next, the configuration of the antenna portion (dielectric plate 305, metal electrode 310, coaxial tube 315) of the plasma processing apparatus 10 according to the present embodiment configured as described above, and the dielectric plate 305 using the metal electrode 310 are described. The holding mechanism will be described in detail.

  As shown in FIG. 3 and FIG. 6 in which the vicinity of the metal electrode is enlarged, the coaxial tubes 315 and 600 are composed of cylindrical inner conductors 315a and 600a and outer conductors 315b and 600b, both of which are made of metal. Has been. The inner conductor 315a is an example of a conductor rod. In particular, in this embodiment, the coaxial tubes 315 and 600 are made of copper having high thermal conductivity and high electrical conductivity so that heat from microwaves and plasma can be released and microwaves can be transmitted satisfactorily. It has become.

  The metal electrode 310 is made of a metal such as aluminum (Al). If the metal electrode 310 is exposed to the plasma side, the electric field concentrates on the metal electrode 310 in the vicinity of the feeding point, plasma having a higher density than the surface of the dielectric plate 305 is generated, and the plasma uniformity is impaired. In addition, the metal electrode 310 may be etched to cause metal contamination. In particular, the electric field strength on a surface substantially parallel to the substrate G is increased.

(simulation)
The electric field strength of the microwave in the sheath in the vicinity of the planes A-C and A-E of the simulation models P1 and P2 shown in FIG. 7 will be described. The inventors covered the surface parallel to the substrate G with the dielectric cover 320 when the surface C parallel to the substrate G is exposed to the substrate G side as it is in the exposed portion of the metal electrode 310 (P1). For the case (P2), the electric field strength in the vicinity of the surfaces A to C and the surfaces A to E (that is, the electric field strength of the microwave in the sheath) was obtained by simulation. From the graph of FIG. 7 showing this result, it has been found that the electric field strength is remarkably increased in the surface C of the surface of the metal electrode 310 exposed in parallel to the substrate G.

  More specifically, when the surface C parallel to the substrate G is exposed to the plasma side (P1), the electric field strength in the vicinity of the surface A under the dielectric plate is relatively low. On the other hand, the electric field strength in the vicinity of the side surface B of the exposed portion of the metal electrode 310 increased as the distance from the surface A increased, but was lower than the electric field strength in the vicinity of the surface C parallel to the substrate G and parallel to the substrate G. The electric field strength in the vicinity of the surface C was significantly higher than those of the other surfaces A and B.

  Next, the inventors performed a simulation for the case where the surface C parallel to the substrate G was covered with an alumina dielectric cover 320 (P2). As a result, it was found that by covering the flat portion with the dielectric cover 320, the electric field strength of the flat portion is remarkably reduced. Although the electric field strength is increased even on the oblique surface B, it is at most about half of the case where it is not covered with the dielectric cover 320. As a result, the inventors have proved that by covering the flat portion with the dielectric cover 320, it is possible to prevent concentration of plasma and generate more uniform plasma.

  Further, it was found from the comparison between P1 and P2 that the electric field in the vicinity of the metal electrode can be weakened and the plasma uniformity can be improved by covering the surface C parallel to the substrate G with the dielectric cover 320.

  6 is covered with a dielectric cover 320 on a surface substantially parallel to the substrate G in the exposed portion of the metal electrode 310 in FIG. In particular, since only one surface such as the bottom surface and the outer peripheral surface of the metal electrode is covered with the dielectric cover 320, the metal electrode 310 and the dielectric cover 320 can be brought into close contact with each other. Thereby, since no gap is generated between the metal electrode 310 and the dielectric cover 320, abnormal discharge can be prevented and plasma can be generated uniformly and stably. Moreover, since high-precision machining is not necessary, the cost can be suppressed. The dielectric cover 320 is made of a porous ceramic.

  The metal electrode 310 is exposed to the surface of the dielectric plate 305 on the substrate side while being connected to the inner conductor 315a of the coaxial waveguide 315 via a through hole 305a provided in the approximate center of the dielectric plate 305. The diameter of the metal electrode 310 is larger than the diameter of the internal conductor 315a, and the surface parallel to the substrate of the metal electrode 310 and the surface parallel to the substrate G of the dielectric plate 305 are partially adjacent to each other. Accordingly, the dielectric plate 305 is lifted by the internal conductor 315a while being held from the substrate side by the metal electrode 310, and is firmly fixed to the inner wall of the processing container 100.

  As described above, the metal electrode 310 is exposed on the substrate side surface of the dielectric plate 305 while projecting outward from the inner conductor 315a of the coaxial waveguide 315. Moreover, since the metal electrode 310 is a metal, its mechanical strength is stronger than that of the dielectric member. As a result, the metal electrode 310 can hold the dielectric plate 305 firmly in terms of structure and material.

  As shown in FIG. 6, the coaxial pipe 315 is provided with a gas introduction path 315c that penetrates the inside of the inner conductor 315a. The gas supply source 800 shown in FIG. 1 communicates with the gas introduction path 315c via the gas line 805. The gas introduction path 315 c communicates with a gas passage 310 a provided inside the metal electrode 310. The gas passage 310 a branches into two annular flow paths and is discharged from the lower surface of the metal electrode 310 to the dielectric cover 320.

  The gas flowing into the dielectric cover 320 decreases its speed while flowing between the pores of the porous ceramic forming the dielectric cover 320, and evenly from the entire surface of the dielectric cover 320 in a state of being slowed to some extent. It is introduced into the processing chamber U. A uniform and good process can be realized by the regular flow of gas in a laminar flow.

The surface on the substrate side of each dielectric plate 305 is formed in a substantially square shape and is symmetrical with respect to the metal electrode 310. For this reason, the microwaves are uniformly emitted from the plurality of dielectric plates 305 disposed over the entire ceiling surface. As a result, plasma can be generated more uniformly below the dielectric plate 305. The dielectric plate 305 is formed of alumina _(Al 2 _{O 3).}

(Optimal shape of metal electrode and dielectric cover)
In order to prevent abnormal discharge from occurring, the inventors have determined the optimum shape of the dielectric cover 320 made of the metal electrode 310 and alumina by simulation as follows.

  In the shape of the metal electrode 310, a basic shape having a width D and a height H shown in FIGS. 15 and 16 and having a rounded tip, a conical shape having a diameter of 32 mm and a height H shown in FIGS. The conical shape having a diameter of 32 mm and a height of 10 mm shown in FIG. 19 and the hemispherical shape shown in FIG. As a combination shape of the metal electrode 310 and the dielectric cover 320, the conical shape shown in FIG. 21 and the conical shape shown in FIG. 22 and FIG.

(simulation result)
The distribution of the electric field strength on the lower surface of the metal electrode 310 and the dielectric plate 305 obtained as a result of executing the simulation under the above conditions will be described with reference to FIGS. First, the inventors fixed the width D to 32 mm and changed the height H to 4 mm, 7 mm, and 10 mm under the above simulation conditions. FIG. 15 shows the electric field strength below the dielectric plate 305 in this case. Γ represents the absolute value of the reflection coefficient (phase in parentheses). The reflection coefficient is an index indicating the reflection of the microwave viewed from the metal electrode side.

  From the results shown in FIG. 15, the inventors found that in the basic form, the electric field becomes stronger on the horizontal plane on the lower surface of the metal electrode 310. The inventors have also confirmed that the concentration of the electric field is not improved even if the height of the metal electrode 310 is changed.

  Therefore, the inventors fixed the height H to 7 mm and changed the width D (diameter of the metal electrode) to 24 mm, 32 mm, and 40 mm, as shown in FIG. However, this result also did not improve the concentration of the electric field in the horizontal plane below the metal electrode.

  Next, the inventors changed the metal electrode 310 into a conical shape and changed the height H to 7, 10, and 13 mm as shown in FIG. As a result, it was found that the concentration of the electric field was improved, and in particular, the electric field was difficult to concentrate on the oblique surface of the metal electrode 310. Further, it was found that the electric field is less likely to be concentrated when the height of the metal electrode 310 is increased within the range of 7, 10, 13 mm.

  However, as shown in FIG. 18, it was found that when the height H is further increased to 16, 19, and 25 mm, the electric field becomes stronger again at the tip of the metal electrode 310.

Next, as shown in FIG. 19, the inventors obtained the distribution of the conical metal electrode 310 and the lower surface of the dielectric plate 305 by simulation when the plasma dielectric constant ε _r was varied. At this time, the diameter of the conical metal electrode 310 was 32 cm, and the height was fixed to 10 mm.

The dielectric loss tangent _Tδ was set to −0.1. The dielectric constant ε _r and the dielectric loss tangent T _δ of the plasma indicate the state of the plasma, the dielectric constant ε _r of the plasma represents the state of polarization in the plasma, and the dielectric loss tangent T _{δ of the} plasma is obtained by exciting the gas. It represents the state of charge loss due to resistance in the generated plasma.

In FIG. 19, the dielectric constant ε _{r of} plasma was changed to −40, −20, and −10. Higher plasma density of the dielectric constant epsilon _r is large plasma represents a high. From the results shown in FIG. 19, the inventor confirmed that the lower the plasma density, the stronger the electric field of the metal electrode 310 and the less spread of the microwave.

  Next, as shown in FIG. 20, the inventors performed the simulation by setting the shape of the metal electrode 310 to a hemispherical shape having a diameter of 32 mm. Also in this case, no electric field concentration was observed on the lower surfaces of the metal electrode 310 and the dielectric plate 305. However, the hemispherical metal electrode 310 is higher than the conical metal electrode 310. Further, making the metal electrode 310 hemispherical is more difficult to process than making it conical.

  Next, as shown in FIG. 21, the inventors provided a conical dielectric cover 320 on a surface horizontal to the object to be processed of the metal electrode 310, and exposed surfaces of the metal electrode 310 and the dielectric cover 320. The shape was substantially conical. The diameter of the bottom surface of the metal electrode 310 was 54 mm, the height was 7 mm, and the height from the bottom surface of the metal electrode 310 to the tip of the dielectric cover 320 was 27 mm. Also in this case, no electric field concentration was observed in the vicinity of the metal electrode 310.

  Furthermore, the inventors simulated the electric field concentration in the case where the tip of the dielectric cover 320 is flat as shown in FIGS. In FIG. 22, the diameter of the bottom surface of the metal electrode 310 is 54 mm, the height is 7 mm, and the height W of the dielectric cover 320 is changed to 12, 10, 8, and 6 mm. As a result, the inventors confirmed that electric field concentration was not observed when the thickness of the dielectric cover was 10 mm or more.

Therefore, the inventors assumed the model shown in FIG. That is, the diameter of the bottom surface of the metal electrode 310 is 54 mm, the height is 7 mm, the height W of the dielectric cover 320 is changed to 10 mm, and the dielectric constant ε _{r of} plasma is −10, −20, −40, −60 And fluctuated. As a result, when the thickness of the dielectric cover 320 was fixed to 10 mm, no electric field concentration was observed in the vicinity of the metal electrode 310 even at a high density.

(Experiment)
Therefore, the inventor conducted an experiment based on the simulation result. The plasma conditions of the experiment are the following four systems.
(1) Ar single gas: 3, 1, 0.5, 0.1, 0.05 Torr
(2) Ar / O ₂ mixed gas: Ar / O ₂ = 160/40, 100/100, 0/200 sccm
(3) Ar / N ₂ mixed gas: Ar / N ₂ = 160/40, 100/100, 0/200 sccm
(4) Ar / NF ₃ mixed gas: Ar / NF ₃ = 180/20, 160/40, 100/100 sccm

In this experimental result, a noteworthy matter is briefly described. When the metal electrode 310 has a conical shape, the electric field is not concentrated in the vicinity of the metal electrode 310, and there is almost no dependency on the pressure of Ar gas and gas types such as O2, N2, and NF3, and good results are obtained. I was able to. When the metal electrode 310 has a hemispherical shape, the pressure dependency on O 2 and NF 3 was relatively high when O ₂ or NF ₃ gas was supplied together with argon gas. When the dielectric cover 320 was attached to the metal electrode 310 and formed into a conical shape, the plasma brightness of the dielectric cover 320 (here, alumina) was darker than that of the metal electrode 310. Moreover, it turned out that the brightness | luminance of the aluminum part of the metal electrode 310 has gas type dependence. In the basic form, the pressure dependence of O ₂ was relatively high.

  Based on the above consideration, the inventor has drawn the following conclusion. First, the metal electrode 310 is preferably formed in a substantially conical shape or a substantially hemispherical shape so as not to concentrate the electric field, and particularly preferably formed in a substantially conical shape. Also, when the dielectric cover 320 is attached to the metal electrode 310, it is preferable that the exposed surfaces of the metal electrode 310 and the dielectric cover 320 have a substantially conical shape. At this time, it is more preferable that the tip of the dielectric cover 320 is formed flat because the electric field does not concentrate on the tip than when the tip is not formed flat. Further, it has been derived that it is more preferable if the height of the dielectric cover 320 whose tip is formed flat is perpendicular to the substrate G within 10 mm.

(Protective film)
The surface of the metal electrode 310 is covered with a protective film of yttria (Y ₂ O ₃ ), alumina (Al ₂ O ₃ ), and Teflon (registered trademark) that has high corrosion resistance. Thereby, it can avoid that the metal electrode 310 is corroded by F-type gas (fluorine radical), chlorine-type gas (chlorine radical), etc. FIG.

The material of this protective film will be specifically described. The protective film coated on the surface of the metal electrode 310 is a film made of an oxide film of a metal whose main component is aluminum, has a thickness of 10 nm or more, and the amount of water released from the film is 1E18 molecule / cm ^2. The metal oxide film may be the following (1 × 10 ¹⁸ pieces / cm ² or less). In the following description, the number of molecules is expressed using the E notation (E-Notation).

  This released water is derived from the surface adsorbed water of the metal oxide film, and the amount of released water is proportional to the effective surface area of the metal oxide film. Therefore, to reduce the amount of released water, the effective surface area should be minimized. It is effective to do. Therefore, it is desirable that the metal oxide film is a barrier type metal oxide film having no pores on the surface.

  A metal oxide film formed by using a specific chemical conversion liquid in a metal whose main component is aluminum whose content of some elements is suppressed does not form voids or gas reservoirs. By suppressing the occurrence of cracks and the like, it has good corrosion resistance against chemicals such as nitric acid and fluorine, and halogen gas, particularly chlorine gas.

The amount of water released from the metal oxide film is the number of water molecules released per unit area released from the film while holding the metal oxide film at 23 ° C. for 10 hours and then holding the temperature at 200 ° C. for 2 hours. [Moleculars / cm ² ] (also included in the measurement during the heating time). The amount of released water can be measured using, for example, an atmospheric pressure ionization mass spectrometer (UG-302P manufactured by Renesas East Japan).

  Preferably, the metal oxide film is obtained by anodizing a metal containing aluminum as a main component or a metal containing high-purity aluminum as a main component in a chemical conversion solution having a pH of 4 to 10. The chemical conversion liquid preferably contains at least one selected from the group consisting of nitric acid, phosphoric acid, organic carboxylic acid, and salts thereof. Moreover, it is preferable that a chemical conversion liquid contains a nonaqueous solvent. The metal oxide film is preferably heat-treated at 100 ° C. or higher after anodic oxidation. For example, annealing can be performed in a heating furnace at 100 ° C. or higher. However, it is more preferable that the metal oxide film is heat-treated at 150 ° C. or higher after anodic oxidation.

  Other layers may be provided above and below the metal oxide film as necessary. For example, it is possible to form a multilayer structure by forming a thin film made of any one or more selected from metals, cermets and ceramics on the metal oxide film.

  In addition, the metal which has aluminum as a main component means the metal which contains aluminum 50 mass% or more. Pure aluminum may be used. Preferably, the metal contains 80 mass% or more of aluminum, more preferably 90 mass% or more, and still more preferably 94 mass% or more of aluminum. The metal mainly composed of aluminum preferably contains at least one metal selected from the group consisting of magnesium, titanium and zirconium.

  Moreover, the metal whose main component is high-purity aluminum is a metal whose main component is aluminum and whose total content of specific elements (iron, copper, manganese, zinc, chromium) is 1% or less. Say. The metal mainly composed of high-purity aluminum preferably contains at least one metal selected from the group consisting of magnesium, titanium and zirconium.

  As described above, according to the plasma processing apparatus 10 according to the present embodiment, the metal electrode 310 is connected to the coaxial tube 315 through the through hole 305a of the dielectric plate 305, and the dielectric electrode 315a is projected from the internal conductor 315a. It is exposed on the surface of the body plate 305 on the substrate side. Thereby, the dielectric plate 305 can be firmly held using the metal electrode 310. Further, by providing the dielectric cover 320 on one surface of the metal electrode 310, the electric field in the vicinity of the metal electrode can be weakened and the uniformity of plasma can be improved.

  Further, in the plasma processing apparatus 10 according to the present embodiment, the dielectric plate is formed of 224 dielectric plates 305. According to this, since the dielectric plate is composed of the plurality of dielectric plates 305, it is easy to perform maintenance such as replacement of parts, and the plasma processing apparatus 10 having high expandability according to the increase in area of the substrate is provided. be able to.

(Modification of the first embodiment)
Next, modifications 1 and 2 of the metal electrode 310 according to the present embodiment will be described.

(Modification 1)
According to the simulation results described above, it has been found that the electric field concentrates particularly on a plane parallel to the substrate G in the exposed portion of the metal electrode 310. Therefore, it is preferable that the exposed portion of the metal electrode 310 has a shape that does not have a plane parallel to the substrate G. As such a modification, for example, the conical shape of FIG. Further, it may be hemispherical as shown in FIG. The metal electrode 310 shown in FIGS. 8 and 9 is advantageous in terms of cost because there is no dielectric cover, and because there is no surface parallel to the substrate G, the electric field is less likely to concentrate. .

  When the exposed portion of the metal electrode 310 has the conical shape shown in FIG. 8, for example, the gas may be introduced obliquely downward 45 degrees from six gas passages 310a provided at equal intervals. Good. In addition, if the conical tip shown in FIG. 8 is rounded, concentration of the electric field can be more effectively prevented.

  When the exposed portion of the metal electrode 310 is hemispherical as shown in FIG. 9, the gas may be introduced radially from, for example, gas passages 310a provided radially at equal intervals.

  Further, the gas passage 310a formed in the metal electrode 310 may be formed so that gas is introduced in a direction parallel to the substrate G as shown in FIG. It may be formed such that gas is introduced into the gas. Note that the dielectric cover 320 of FIG. 10 is formed of alumina ceramic.

  Further, when a porous ceramic dielectric cover 320 is provided on the exposed portion of the metal electrode 310, the gas chamber 310a of the metal electrode 310 is passed through the dielectric cover 320 to the processing chamber U as shown in FIG. It may be introduced.

(Modification 2)
An XX cross section of FIG. 11 is shown in FIG. FIG. 11 is a view of FIG. 12 cut along the YY plane. As shown in FIG. 11, the metal electrode 310 extends so that its root is inserted into the through hole 305 a of the dielectric plate 305, and the inner conductor 315 a of the coaxial tube 315 and the metal electrode 310 are connected to the inner conductor. The male screw 315d provided at the end of 315a and the female screw 310b provided at the base of the metal electrode 310 are connected by being screwed together.

  In the ring-shaped dielectric 410 and the O-ring 415b of FIG. 6, first, the O-ring 415b is fitted, and then the ring-shaped dielectric 410 is mounted. When the ring-shaped dielectric 410 is attached, the O-ring 415b may be damaged. However, in the structure of FIG. 11, the upper corner of the dielectric plate 305 is tapered. Accordingly, the dielectric plate 305 can be smoothly fitted, and the O-ring 415b is hardly damaged when the dielectric plate 305 is attached.

  In the present modification, the dielectric plate 305 and the ring-shaped dielectric 410 shown in FIG. 3 may be integrally formed as shown in FIG. Further, instead of providing two O-rings 415 a and 415 b between the inner peripheral surface of the dielectric plate 305 and the coaxial tube 315 and between the outer peripheral surface of the dielectric plate 305 and the lid body 300, An O-ring 415 b may be provided between the inner peripheral surface and the metal electrode 310, and an O-ring 415 a may be provided between the outer peripheral surface of the dielectric plate 305 and the lid body 300. Also by this, the dielectric plate 305 can be firmly held on the ceiling surface by the metal electrode 310 and the inner conductor 315a, and the inside of the processing chamber U can be vacuum-sealed.

  In the above embodiment, the operations of the respective units are related to each other, and can be replaced as a series of operations in consideration of the relationship between each other. And by replacing in this way, the embodiment of the invention of the plasma processing apparatus can be made an embodiment of a method for using the plasma processing apparatus and a method for cleaning the plasma processing apparatus.

(Frequency limitation)
By using the plasma processing apparatus 10 according to each of the above embodiments and outputting a microwave having a frequency of 1 GHz or less from the microwave source 900, a favorable plasma process can be realized. The reason will be described below.

  In the plasma CVD process in which a thin film is deposited on the substrate surface by a chemical reaction, the film adheres not only to the substrate surface but also to the inner surface of the processing container. If the film adhering to the inner surface of the processing vessel peels off and adheres to the substrate, the yield is deteriorated. Furthermore, the impurity gas generated from the film adhering to the inner surface of the processing vessel may be taken into the thin film and the film quality may be deteriorated. Therefore, in order to perform a high quality process, the inner surface of the chamber must be periodically cleaned.

F radicals are often used for cleaning silicon oxide films and silicon nitride films. F radicals etch these films at high speed. F radicals are generated by exciting plasma with a gas containing F such as NF ₃ or SF ₆ to decompose gas molecules. When the plasma is excited with a mixed gas containing F and O, F and O recombine with electrons in the plasma, so that the electron density in the plasma decreases. In particular, when plasma is excited with a gas containing F having the highest electronegativity among all substances, the electron density is significantly reduced.

In order to prove this, the inventors measured the electron density by generating plasma under conditions of a microwave frequency of 2.45 GHz, a microwave power density of 1.6 W / cm ⁻² , and a pressure of 13.3 Pa. As a result, the electron density was 2.3 × 10 ¹² cm ⁻³ in the case of Ar gas, whereas 6.3 × 10 ¹⁰ cm ^{− in} the case of NF ₃ gas was smaller by one digit or more. ³ .

As shown in FIG. 13, when the microwave power density is increased, the electron density in the plasma is increased. Specifically, when the power density is changed from 1.6 W / cm ² to 2.4 W / cm ² , the electron density in the plasma is from 6.3 × 10 ¹⁰ cm ⁻³ to 1.4 × 10 ¹¹ cm ^−3. To increase.

On the other hand, upon application of a 2.5 W / cm ² or more microwave, to increases risk of the dielectric plate is abnormal discharge respective portions or cracked by heating, because it is uneconomical, practically the NF ₃ gas 1. It is difficult to obtain an electron density of 4 × 10 ¹¹ cm ⁻³ or more. That is, since the electron density to generate a uniform and stable plasma at extremely low NF ₃ gases, surface wave resonance density _{n s} is must be 1.4 × ¹⁰ 11 ^{cm -3} or less.

Surface wave resonance density n _s denotes the electron density surface waves lowest possible propagation between the dielectric plate and the plasma, the electron density is smaller than the surface wave resonance density n _s, because the surface wave does not propagate Only very non-uniform plasmas can be excited. Surface wave resonance density _{n s} is proportional relationship indicated by the cut-off density _{n c} and of formula (1) (2).
n _c = ε _{0 me} ω ² / e ² (1)
n _s = n _c (1 + ε _r ) (2)
Here, epsilon ₀ is the vacuum dielectric constant, is m _e the electron mass, omega microwave angular frequency, e is elementary charge, epsilon _r is the relative permittivity of the dielectric plate.

From the formula (1) (2), the surface wave resonance density n _s, it is found to be proportional to the square of the microwave frequency. Therefore, when the low frequency is selected, the surface wave propagates even at a lower electron density, and a uniform plasma can be obtained. For example, when the microwave frequency is halved, a uniform plasma can be obtained even with an electron density of ¼, and the reduction of the microwave frequency is extremely effective for expanding the process window.

The frequency at which the surface wave resonance density n _s is equal to 1.4 × 10 ¹¹ cm ⁻³ , which is a practical electron density when NF ₃ gas is used, is 1 GHz. That is, if a frequency of 1 GHz or less is selected as the microwave frequency, uniform plasma can be excited with a practical power density using any gas.

  From the above, for example, by outputting a microwave having a frequency of 1 GHz or less from the microwave source 900, a good plasma treatment can be performed on the object to be processed (for example, the substrate G).

  For example, by outputting a microwave having a frequency of 1 GHz or less from the microwave source 900 of the plasma processing apparatus 10 according to the above-described embodiment, the microwave output from the microwave source 900 is converted into a coaxial tube (for example, the coaxial tubes 600 and 315). The dielectric plate is connected to the inner conductor 315a of the coaxial waveguide through a through hole 305a formed in the dielectric plate 305, and at least part of the dielectric plate is adjacent to the substrate side surface of the dielectric plate 305. The microwave transmitted through the coaxial tube 315 is transmitted through the dielectric plate 305 held on the inner wall of the processing container 100 by the metal electrode 310 exposed from the surface of the substrate 305, and is emitted into the processing container 100. The plasma treatment is performed by exciting the processing gas introduced into the processing container 100 by the generated microwave and performing a desired plasma processing on the object to be processed. It can be a method of use of the apparatus.

  Further, for example, by outputting a microwave having a frequency of 1 GHz or less from the microwave source 900 of the plasma processing apparatus 10 according to the above-described embodiment, the microwave output from the microwave source 900 is converted into a coaxial tube (for example, the coaxial tube 600, 315) and coupled to the inner conductor 315a of the coaxial tube through a through hole 305a formed in the dielectric plate 305, and at least part of the dielectric plate 305 is adjacent to the substrate side surface of the dielectric plate 305. The microwave transmitted through the coaxial tube 315 is transmitted through the dielectric plate 305 held on the inner wall of the processing container 100 by the metal electrode 310 exposed from the substrate side surface of the body plate 305 and is emitted into the processing container 100. The plasma processing apparatus is cleaned by exciting the cleaning gas introduced into the processing container 100 by the emitted microwave. It can be a cleaning method that plasma processing apparatus.

  The introduction of “Microwave Plasma Technology” published by Ohmsha, published on September 25, 2003, edited by the IEEJ / Microwave Plasma Research Special Committee, In this specification, the microwave frequency is set to 300 MHz or higher.

  However, in the above-described embodiment, the microwave source 900 that outputs a microwave of 915 MHz is described, but a microwave source that outputs a microwave of 896 MHz, 922 MHz, and 2.45 GHz may be used. The microwave source corresponds to an electromagnetic wave source that generates an electromagnetic wave (microwave) for exciting plasma.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, the dielectric plate provided in the plasma processing apparatus according to the present invention may be a plasma processing apparatus having a plurality of rectangular dielectric plates 305. As shown in FIG. A plasma processing apparatus having a circular dielectric plate 305 may be used.

  According to this, one dielectric plate 305 is disposed on the ceiling portion of the processing container 100 by one metal electrode 310 connected to one inner conductor 315a. According to this, as in the case of the plasma processing apparatus having a plurality of dielectric plates 305, the side surfaces of the dielectric plates 305 are in contact with the plasma during the process.

  In such a state, when the dielectric plate 305 is in contact with another member (for example, a metal frame or the like) on the side surface of the dielectric plate 305, a gap between the dielectric plate 305 and those members is used. It is possible to avoid a phenomenon in which plasma enters and abnormal discharge occurs.

  Further, a ring-shaped dielectric 420 through which the inner conductor 315a penetrates is provided at the center of the ring-shaped dielectric 410 between the lid 300 and the inner conductor 315a. A part of the outer peripheral surface and inner peripheral surface of the ring-shaped dielectric 420 is embedded in the lid 300 and the inner conductor 315a. An O-ring 425 is provided on the surface (lower surface) between the ring-shaped dielectric 420 and the lid 300 and facing the inside of the processing container.

  As described above, in the plasma processing apparatus 10 illustrated in FIG. 14, the O-ring 425 is provided to lift the dielectric plate 305. According to this, the inner conductor 315a of the coaxial tube can be pushed up to the outside of the processing container 100 by the elastic force (repulsive force) of the O-ring 425 with respect to the processing container 100.

  Furthermore, by providing the two ring-shaped dielectrics 410 and 420, the inner conductor 315a holding the dielectric plate 305 is supported at two points, so that the shaft of the coaxial tube 315 can be prevented from shaking. In this manner, the dielectric plate 305 is firmly attached to the inner wall of the lid 300 by the elastic force of the spring and the guide function of the inner conductor 315a. As a result, the plasma can be generated uniformly and stably by avoiding the abnormal discharge that occurs when the plasma enters the gap between the inner wall of the lid 300 and the dielectric plate 305.

  Note that the plasma processing apparatus according to the present invention can process a large-area glass substrate, a circular silicon wafer, and a square SOI (Silicon On Insulator) substrate.

  In the plasma processing apparatus according to the present invention, any plasma processing such as film formation processing, diffusion processing, etching processing, and ashing processing can be performed.

It is a longitudinal cross-sectional view of the plasma processing apparatus concerning 1st Embodiment of this invention. It is the figure which showed the ceiling surface of the plasma processing apparatus concerning the embodiment. It is the figure which showed the branched waveguide concerning the embodiment. It is the figure which showed the fixing mechanism of the dielectric material plate concerning the embodiment, and its vicinity. It is the figure which showed the branch plate concerning the embodiment. It is the figure which showed the metal electrode concerning the embodiment and its vicinity. It is the graph which showed the relationship between the shape of the metal electrode concerning the same embodiment, and electric field strength. It is the figure which showed the modification of the metal electrode concerning the embodiment. It is the figure which showed the other modification of the metal electrode concerning the embodiment. It is the figure which showed the other modification of the metal electrode concerning the embodiment. It is the figure which showed the other modification of the metal electrode concerning the embodiment. It is XX sectional drawing of FIG. It is a graph which shows the relationship between the power density of a microwave, and the electron density of plasma. It is the figure which showed the other modification. It is a simulation result for optimizing the shape (basic form) of a metal electrode. It is another simulation result for optimizing the shape (basic form) of a metal electrode. It is another simulation result for optimizing the shape (conical shape) of a metal electrode. It is a simulation result for optimizing the shape (conical shape) of a metal electrode. It is another simulation result for optimizing the shape (conical shape) of a metal electrode. It is a simulation result for optimizing the shape (hemisphere) of a metal electrode. It is a simulation result for optimizing the shape of a dielectric cover. It is another simulation result for optimizing the shape of a dielectric cover. It is another simulation result for optimizing the shape of a dielectric cover.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Plasma processing apparatus 100 Processing container 200 Container main body 300 Lid body 300a Groove 305 Dielectric board 305a Through-hole 310 Metal electrode 315,600 Coaxial tube 315a, 600a Inner conductor 320 Dielectric cover 410,420 Ring-shaped dielectric body 205,415a 415b, 425 O-ring 500 Fixing mechanism 520 Short-circuit portion 600 Coaxial tube 600a Inner conductor 610 Branch plate 800 Gas supply source 900 Microwave source 905 Branch waveguide U Processing chamber

Claims (26)

A plasma processing apparatus that plasmas a target object by exciting a gas with electromagnetic waves,
A processing vessel;
An electromagnetic wave source that outputs electromagnetic waves;
A conductor rod for transmitting electromagnetic waves output from the electromagnetic wave source;
A dielectric plate that is formed with a through hole and transmits the electromagnetic wave transmitted through the conductor rod and emits it into the processing container; and
A surface of the dielectric plate on the workpiece side in a state where the dielectric plate is connected to the conductor rod through a through hole formed in the dielectric plate and at least a part of the dielectric plate is adjacent to the surface of the dielectric plate on the workpiece side. And a metal electrode exposed from
A plasma processing apparatus, wherein one of exposed surfaces of the metal electrode is covered with a dielectric cover. A plasma processing apparatus that plasmas a target object by exciting a gas with electromagnetic waves,
A processing vessel;
An electromagnetic wave source that outputs electromagnetic waves;
A conductor rod for transmitting electromagnetic waves output from the electromagnetic wave source;
A dielectric plate that is formed with a through hole and transmits the electromagnetic wave transmitted through the conductor rod and emits it into the processing container; and
A surface of the dielectric plate on the workpiece side in a state where the dielectric plate is connected to the conductor rod through a through hole formed in the dielectric plate and at least a part of the dielectric plate is adjacent to the surface of the dielectric plate on the workpiece side. And a metal electrode exposed from
The plasma processing apparatus, wherein the exposed surface of the metal electrode does not have a surface substantially parallel to the object to be processed. The diameter of the metal electrode is
The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is larger than a diameter of the conductor rod. The exposed surface of the metal electrode is
The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is formed in a substantially conical shape or a substantially hemispherical shape.   5. The plasma processing apparatus according to claim 1, wherein a surface of the exposed surface of the metal electrode that is substantially parallel to the processing body is covered with the dielectric cover.   The plasma processing apparatus according to claim 1, wherein the dielectric cover is formed of a porous ceramic.   The plasma processing apparatus according to claim 1, wherein the through hole of the dielectric plate is provided at substantially the center of the dielectric plate.   The plasma processing apparatus according to claim 1, wherein a surface of the metal electrode is covered with a protective film. Inside the conductor rod, a gas introduction path for flowing gas is formed,
The metal electrode is formed with a gas passage that communicates with a gas introduction path formed inside the conductor rod and introduces a gas flowing through the gas introduction path into the processing container. The plasma processing apparatus described in any one of. The gas passage formed in the metal electrode is
The plasma processing apparatus according to claim 9, wherein the plasma processing apparatus is formed so that gas is introduced in a direction substantially parallel to the object to be processed. The gas passage formed in the metal electrode is
The plasma processing apparatus according to claim 9, wherein the plasma processing apparatus is configured to introduce a gas in a direction substantially perpendicular to the object to be processed. The gas passage formed in the metal electrode is
The plasma processing apparatus according to claim 9, wherein the plasma processing apparatus is formed so that gas is introduced radially.   The plasma processing apparatus according to claim 9, wherein the gas is directly introduced into the processing container from the gas passage.   The plasma processing apparatus according to claim 9, wherein the gas is introduced into the processing container from the gas passage through the dielectric cover. A plurality of the dielectric plates are provided,
The plasma processing apparatus according to claim 1, wherein a plurality of the metal electrodes are provided corresponding to the plurality of dielectric plates. Each dielectric plate of the plurality of dielectric plates is:
The plasma processing apparatus according to claim 15, wherein the surface of the object to be processed is formed to have a substantially rectangular shape. Each dielectric plate of the plurality of dielectric plates is:
The plasma processing apparatus according to claim 16, wherein the surface to be processed is formed so as to be substantially square.   The plasma processing apparatus according to claim 1, wherein the electromagnetic wave source outputs an electromagnetic wave having a frequency of 1 GHz or less.   The plasma processing apparatus according to claim 1, wherein a side surface of the dielectric plate is in contact with plasma during the process. A conductor rod for transmitting electromagnetic waves;
A dielectric plate that is formed with a through hole and transmits the electromagnetic wave transmitted through the conductor rod and emits it into the processing container; and
The dielectric plate is connected to the conductor rod through a through hole formed in the dielectric plate, and at least part of the dielectric plate is adjacent to the surface of the dielectric plate on the object side. A metal electrode exposed from the surface on the processing body side,
An antenna in which one of exposed surfaces of the metal electrode is covered with a dielectric cover. A conductor rod for transmitting electromagnetic waves;
A dielectric plate that is formed with a through hole and transmits the electromagnetic wave transmitted through the conductor rod and emits it into the processing container; and
A surface of the dielectric plate on the workpiece side in a state where the dielectric plate is connected to the conductor rod through a through hole formed in the dielectric plate and at least a part of the dielectric plate is adjacent to the surface of the dielectric plate on the workpiece side. And a metal electrode exposed from
The exposed surface of the metal electrode is an antenna having no surface substantially parallel to the object to be processed. An electromagnetic wave having a frequency of 1 GHz or less is output from an electromagnetic wave source,
Transmitting the electromagnetic wave to a conductor rod;
The dielectric plate is connected to the conductor rod through a through hole formed in the dielectric plate, and at least part of the dielectric plate is adjacent to the surface of the dielectric plate to be processed from the surface of the dielectric plate to be processed. The dielectric plate held on the inner wall of the processing container by the exposed metal electrode transmits the electromagnetic wave transmitted through the conductor rod and emits it into the processing container,
A method for using a plasma processing apparatus, wherein a processing gas introduced into the processing container is excited by the emitted electromagnetic wave to perform a desired plasma processing on an object to be processed. An electromagnetic wave having a frequency of 1 GHz or less is output from an electromagnetic wave source,
Transmitting the electromagnetic wave to a conductor rod;
The dielectric plate is connected to the conductor rod through a through hole formed in the dielectric plate, and at least part of the dielectric plate is adjacent to the surface of the dielectric plate to be processed from the surface of the dielectric plate to be processed. The dielectric plate held on the inner wall of the processing container by the exposed metal electrode transmits the electromagnetic wave transmitted through the conductor rod and emits it into the processing container,
A cleaning method for a plasma processing apparatus, wherein a cleaning gas introduced into the processing container is excited by the emitted electromagnetic wave to clean the plasma processing apparatus.   The plasma processing apparatus according to claim 5, wherein exposed surfaces of the metal electrode and the dielectric cover are formed in a substantially conical shape.   The plasma processing apparatus according to claim 24, wherein a tip end of the dielectric cover is formed flat.   26. The plasma processing apparatus according to claim 25, wherein a height of the dielectric cover in a direction perpendicular to the object to be processed is within 10 mm.