JP2005197371A - Method and apparatus for generating high area/high density plasma by microwave discharge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for generating a large-area/high-density plasma by microwave discharge to cope with both increase of the plasma density and increase of the plasma area. <P>SOLUTION: A dielectric window 10 and a dielectric plate 2 are separated from each other to allot functions to them. A vacuum tank 1 to be a plasma generating chamber is vacuum-shielded with the small dielectric window 10, and the large-area dielectric plate 2 is mounted on the inner wall of a metal wall 9 at the vacuum side. A microwave is irradiated through the dielectric window 10 in front of an slot antenna 5 from the air side to propagate a surface wave at its frequency along the large-area dielectric plate 2, thus generating a high density plasma. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for generating a large-area, high-density plasma using a microwave discharge and an apparatus therefor.

Currently, large-area thin film deposition and processing techniques are required for night display (LCD) and solar cells. In the case of a liquid crystal display, a 1 meter square (area 1 m ² ) thin film is produced using a low density (−10 ¹⁰ / cm ³ ) capacitively coupled plasma.

However, in the future, an increase in area of electronic devices is inevitably required from the viewpoint of demand, and a thin film having a large area of about 3 m square (> 10 m ² ) is required, and productivity and film quality are improved. In order to improve, development of a new technology using plasma with a high density (> 10 ¹¹ / cm ³ ), which is one digit higher than conventional ones, is required.

  In order to realize such a large-area thin film plasma process, it is necessary to simultaneously achieve the two problems of increasing the plasma density and increasing the area. Currently, capacitively coupled high-frequency discharges are used, and it is considered that a large area can be achieved by extending the conventional technology. However, it is impossible to achieve high density in view of the discharge principle. close.

  On the other hand, high-density plasma can be obtained even with the same high-frequency discharge using inductively coupled discharge. However, when the area is about 3 meter square, several tens of discharge antennas, power supply, and matching unit are required for discharge. Thus, it is difficult to obtain a uniform density distribution.

  As another method for obtaining high-density plasma, there is a technique using microwave discharge as shown in FIG. In the figure, 1 is a vacuum vessel that becomes a plasma generation chamber, 2 is a dielectric plate that forms the upper surface of the vacuum vessel, 3 is a metal shield that covers the dielectric plate, 4 is a waveguide, 5 is a slot antenna, 6 Is an O-ring for vacuum sealing.

  In the plasma generator configured in this way, a microwave introduced from the waveguide 4 forms a microwave irradiation antenna (usually a slot antenna) 5 by coupling with a window hole of the metal shield 3, and the slot A microwave is irradiated from the atmosphere side through the dielectric window on the front surface of the antenna into the vacuum vessel 1 filled with the low pressure reactive gas from the antenna 5, and the surface wave of that frequency is propagated along the dielectric plate 2. To generate a high density plasma.

  However, such a conventional plasma generator performs vacuum sealing of the vacuum vessel 1 via the O-ring 6 using the dielectric plate 2 itself for surface wave propagation, and the dielectric plate 2 covers the slot antenna 5. It also serves as a dielectric window. Here, as the dielectric material, various oxides such as quartz and alumina are often used, and nitrides and carbides can also be used.

As a result, as the plasma becomes a large area (large diameter), the atmospheric pressure applied to the dielectric plate becomes enormous. Necessary. For example, when a quartz disk is used, a force of 8 tons is applied to a material with a diameter of 1 m ^2, and thus a thickness of 7 cm or more, and a material having a diameter of 3 m ² increases to a force of 73 tons. If the above thick quartz plate is not used, the quartz plate will break under the pressure difference between the atmosphere and vacuum.

  As a further improvement of the conventional plasma generator, the one shown in FIG. 5 is also known. In the figure, the same components as those in FIG. DESCRIPTION OF SYMBOLS 1 is a vacuum vessel which becomes a plasma generation chamber, 2 is a dielectric plate forming the upper surface of the vacuum vessel, 3 is a metal shield covering the dielectric plate, 4 is a waveguide, 5 is a slot antenna, and 6 is a vacuum seal O-rings, 7 is a support frame, and 8 is a metal support.

  The plasma generator of FIG. 5 is provided with two waveguides 4, each having a slot antenna 5 formed in a vacuum vessel 1 filled with a low pressure reactive gas, from the atmosphere side to the front of the antenna. A high-density plasma is generated by irradiating a microwave through the dielectric window and propagating a surface wave of that frequency along each dielectric plate 2.

  In this type, since plasma is generated by two plasma generators, the dielectric plate 2 can be made thinner than that in FIG. 4 and does not need to have a large area. The vacuum vessel 1 is sealed using itself, and the dielectric plate 2 also serves as a dielectric window that covers the slot antenna 5, so that a large force from the atmosphere is applied to the dielectric plate, and the lifetime has passed. After replacement, it was not easy.

In addition, a plurality of waveguides are arranged in parallel at equal intervals in the plasma generation chamber, and each waveguide is formed with a coupling hole having a coupling coefficient sequentially increased toward the tip side. Is a dielectric window that is divided and formed corresponding to each coupling hole, and radiates it from each coupling hole into the plasma generating chamber to generate a large-area plasma with a uniform density. A plasma generating apparatus is known in which a body plate itself is used to perform vacuum sealing of a vacuum container, and the dielectric plate also serves as a dielectric window that covers the slot antenna (see, for example, Patent Document 1).
JP 2002-280196 A

  In this way, the vacuum seal of the vacuum vessel is performed using the conventional dielectric plate itself, and the dielectric plate also needs a thick and expensive dielectric material in the plasma generator that also serves as a dielectric window covering the slot antenna. As a maintenance when the material surface is destroyed due to abnormal discharge or the like, or when it is worn out by plasma, there is a problem that it cannot be easily replaced with a new dielectric plate. Therefore, the present invention adopts microwave discharge, and does not use a thick and expensive dielectric plate, and does not use a thick and expensive dielectric plate. It aims at obtaining the production | generation method and apparatus.

  In order to achieve the above object, according to a first aspect of the present invention, there is provided a method for generating a large area and high density plasma by microwave discharge, wherein a vacuum container serving as a plasma generation chamber is vacuum sealed with a small dielectric window, The dielectric plate of the area is attached to the inner wall of the metal wall on the vacuum side, irradiated with microwaves from the atmosphere side through the dielectric window in front of the antenna, and the surface wave of that frequency propagates along the dielectric plate of the large area To generate high-density plasma.

  As a result, a small-area dielectric window for vacuum sealing and a large-area dielectric plate are separately arranged to share functions, and a thick and expensive dielectric plate is used by adopting microwave discharge. Therefore, both high-density plasma and large area can be achieved.

  According to a second aspect of the present invention, there is provided a plasma generation apparatus for generating plasma by supplying microwave energy to a plasma generation chamber via a waveguide. A small-area dielectric window for vacuum sealing and a large-area dielectric plate are separately placed in a vacuum vessel that serves as a plasma generation chamber. The small-area dielectric window corresponds to the coupling hole of the waveguide. The dielectric plate having the area was mounted on the inner wall of the metal wall forming the upper surface of the vacuum vessel on the vacuum side.

  As a result, vacuum sealing is performed with a dielectric window having a small area, and a dielectric plate with a large area is attached to the inner wall of the metal wall on the vacuum side, so that the atmospheric pressure applied to the wall of the vacuum vessel is made of this metal. Since the wall supports the dielectric plate, no force from the atmosphere is applied to the dielectric plate, so that a thin and inexpensive dielectric plate can be used, and replacement after the end of its useful life is facilitated.

  According to a third aspect of the present invention, there is provided a plasma generation apparatus for generating plasma by supplying microwave energy to a plasma generation chamber via a waveguide. A vacuum container serving as a plasma generation chamber is provided with a small-area dielectric window for vacuum sealing and a large-area dielectric plate, and a plurality of small-area dielectric windows are provided. Corresponding to a coupling hole in which a plurality of elongated slots are cut on the bottom of the waveguide, microwaves are incident on the container through a dielectric window for vacuum sealing, and a large area dielectric plate is vacuumed on the vacuum side. It was constructed by mounting on the inner wall of the metal wall that forms the upper surface of the container.

  As a result, a dielectric window for vacuum sealing corresponding to a plurality of elongated slots on the bottom surface of the waveguide is provided, and a microwave is incident on the container through the dielectric window, whereby surface waves are generated along the surface of the dielectric plate. Propagating and generating uniform large area plasma.

  According to a fourth aspect of the present invention, there is provided a plasma generation apparatus for generating plasma by supplying microwave energy to a plasma generation chamber via a waveguide. A small-area dielectric window for vacuum sealing and a large-area dielectric plate are separately placed in a vacuum vessel that serves as a plasma generation chamber. The small-area dielectric window corresponds to the coupling hole of the waveguide. The dielectric plate having the area was configured to be mounted on the inner wall of the metal wall forming the upper surface of the vacuum vessel on the vacuum side, and the dielectric material was composed of oxide or nitride such as quartz or alumina, carbide or the like.

  As described above, the dielectric window and the dielectric plate are separated, and the functions are assigned to each of them. That is, vacuum sealing is performed with a dielectric window with a small area, and a dielectric plate with a large area is attached to the inner wall of the metal wall on the vacuum side, so that the atmospheric pressure applied to the wall of the vacuum vessel Therefore, since no force from the atmosphere is applied to the dielectric plate, a thin and inexpensive dielectric plate can be used, and replacement after the end of its useful life is facilitated.

  The present invention employs microwave discharge in order to achieve both high density and large area of plasma, and a vacuum container serving as a plasma generation chamber, a small area dielectric window for vacuum sealing, and a large area dielectric. The body plate is separated, the small area dielectric window corresponds to the coupling hole of the waveguide, the large area dielectric plate is attached to the inner wall of the metal wall on the vacuum side, and the dielectric window and the dielectric plate , And share the functions with each other. That is, vacuum sealing is performed with a dielectric window having a small area, and a dielectric plate having a large area is attached to the inner wall of the metal wall on the vacuum side.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an apparatus for generating large area and high density plasma by microwave discharge according to the present invention. In the figure, 1 is a vacuum vessel serving as a plasma generation chamber, 2 is a dielectric plate forming the upper surface of the vacuum vessel, 4 is a waveguide, 5 is a slot antenna, 6 is an O-ring for vacuum sealing, and 9 is a metal wall. Reference numeral 10 denotes a dielectric window.

  In a plasma generation apparatus that generates plasma by supplying microwave energy to a plasma generation chamber via a waveguide, a small-area dielectric window 10 that performs vacuum sealing on a vacuum container 1 that serves as a plasma generation chamber; A large-area dielectric plate 2 is arranged separately, a small-area dielectric window 10 is made to correspond to the coupling hole of the waveguide 4 to form a slot antenna 5, and the large-area dielectric plate 2 is the upper surface of the vacuum vessel 1. Is attached to the inner wall on the vacuum side of the metal wall 9 to form a plasma generating apparatus.

  The vacuum vessel 1 serving as a plasma generation chamber is vacuum-sealed by a small dielectric window 10, and the large-area dielectric plate 2 is attached to the inner wall of the metal wall 9 on the vacuum side, and the front surface of the slot antenna 5 from the atmosphere side. A high-density plasma is generated by irradiating a vacuum vessel 1 filled with a low-pressure reactive gas with a microwave through a dielectric window 10 and propagating surface waves of that frequency along a dielectric plate 2 having a large area. To do.

  In this way, the dielectric window 10 and the dielectric plate 2 are separated, and the functions are assigned to each of them. That is, the dielectric window 10 having a small area is vacuum-sealed, and the dielectric plate 2 having a large area is attached to the inner wall of the metal wall 9 on the vacuum side, so that the atmospheric pressure applied to the wall of the vacuum vessel 1 is equal to this. Since the metal wall 9 supports the dielectric plate 2, no force from the atmosphere is applied to the dielectric plate 2. Therefore, a thin and inexpensive dielectric plate can be used, and replacement after the end of its useful life is facilitated.

  Next, as an actual embodiment, in a metal vacuum vessel having a rectangular parallelepiped shape having a length of 1 m in the axial direction (z direction) and a length of 0.3 m in the horizontal direction (x direction) and the vertical direction (y direction), An attempt was made to generate plasma having a large area of 1 m × 0.3 m by microwave discharge.

  2 and 3 schematically show cross-sectional views in the xz plane of the device. A microwave having a frequency of 2.45 GHz and a power of 0.3 to 1.0 kW is introduced along a TE10 mode rectangular waveguide (cross-sectional size: 96 mm × 27 mm). A plurality of (two in this example) elongated slots (width 30 mm, length 1 m) are cut on the bottom surface of the waveguide, and then a dielectric window for vacuum sealing (material: quartz, width 15-30 mm, length 40 mm). ) Through the container. The gas used was argon and the pressure was 0.2 Torr.

  As shown in FIG. 2, when a quartz plate (thickness 10 mm, width 30 cm, length 1 m) was mounted on the inner surface of the metal wall, it was found that the plasma spread to the full in the lateral direction (x direction). This is because by installing the dielectric plate, surface waves propagate along the surface and plasma is generated. This experiment demonstrates that a uniform large area plasma can be generated by placing a thin quartz plate of only 10 mm on the inner surface of a metal container.

  On the other hand, FIG. 3 is a comparative example in which microwaves are incident on the metal wall (thickness 40 mm) as it is, and the plasma is localized in a form attached to the dielectric window directly under the slot antenna, and then from there. It does not spread in the direction. That is, it was confirmed that two elongated plasmas having a width of about 3 cm and a length of 1 m were generated, and the intended uniform large-area plasma could not be generated.

  The method for generating plasma by microwave discharge and the apparatus therefor according to the present invention can be used in electronics, electronic device manufacturing apparatus, and plasma application apparatus that require large-area and high-density plasma.

The block diagram of the generator of the large area and high-density plasma by the microwave discharge of this invention. The Example figure of this invention. The comparative example figure with this invention. The block diagram of the production | generation apparatus of the plasma by the conventional microwave discharge. The other block diagram of the production | generation apparatus of the plasma by the conventional microwave discharge.

Explanation of symbols

1 Vacuum container (plasma generation chamber)
2 Dielectric plate 3 Metal shield 4 Waveguide 5 Slot antenna 6 O-ring for vacuum seal 7 Support frame 8 Metal support 9 Metal wall 10 Dielectric window

Claims (4)

  Vacuum sealing is performed with a small dielectric window on the vacuum vessel that becomes the plasma generation chamber, and a large area dielectric plate is attached to the inner wall of the metal wall on the vacuum side, and microwaves are transmitted from the atmosphere side through the dielectric window on the front of the antenna. A method for generating a large-area, high-density plasma by microwave discharge, characterized in that a high-density plasma is generated by irradiating and propagating surface waves of that frequency along a large-area dielectric plate.   In a plasma generation apparatus that generates plasma by supplying microwave energy to a plasma generation chamber via a waveguide, a small-area dielectric window that performs vacuum sealing on a vacuum container that serves as the plasma generation chamber, and a large area The dielectric plate is mounted separately on the inner wall of the metal wall that forms the upper surface of the vacuum vessel on the vacuum side, with the dielectric window corresponding to the coupling hole of the waveguide. Large-area, high-density plasma generator using microwave discharge.   A plurality of the small-area dielectric windows are provided, a plurality of elongated slots are cut on a bottom surface of the waveguide, and microwaves are incident on the container through the vacuum sealing dielectric window. 2. A large-area, high-density plasma generator by microwave discharge as described in 2. 3. The apparatus for generating large-area and high-density plasma by microwave discharge according to claim 2, wherein the dielectric material is an oxide such as quartz or alumina, nitride, carbide or the like.

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