JPWO2014184824A1 - Plasma processing apparatus and sealing method thereof - Google Patents

Abstract

A plasma processing apparatus capable of improving characteristics of a film formed by plasma processing is provided. A processing chamber (10) defining a sealed space (11), a plasma forming electrode (36) provided in the sealed space, and an opening formed in the processing chamber (10) from the outside of the processing chamber (10). Through (13h), the inner conductor (21) extending toward the plasma forming electrode (36) and the inner conductor (21) are surrounded, and a gap (23) is defined between the inner conductor (21). In addition, the outer conductor (22, 13) that defines the opening (13h), the inner conductor (12), and the outer conductor (22, 13) are connected to each other so that the gap (23) is connected to the atmosphere-side space and the sealed space ( 11) The seal member (60) formed of an insulator for separation from the space communicating with the space (11) and the gap (23) are formed on the sealed space (11) side with respect to the seal member (60). Insulation for preventing discharge filling the space (100) and a.

Description

  The present invention relates to a plasma processing apparatus that performs plasma processing on a substrate and a sealing method thereof.

  In a manufacturing process of a flat display, a solar cell, a semiconductor device, etc., a plasma processing apparatus is used for forming a thin film, etching, and the like. As the plasma processing apparatus, the present inventors have proposed one disclosed in Patent Document 1 and the like.

  Here, FIG. 7 is a cross-sectional view showing an outline of a plasma processing apparatus of the same type as that of Patent Document 1. This apparatus is connected to a metal processing chamber 10 that defines a sealed space 11, a susceptor 14 installed in the processing chamber 10 for placing a substrate 16, and a lid 13 that forms the upper part of the processing chamber 10. The coaxial tube 20, the dielectric plate 34 provided on the lower surface of the lid 13 above the susceptor 14, and an electrode 36 installed on the surface of the dielectric plate 34. The inner conductor 21 of the coaxial tube 20 extends to the upper surface of the dielectric plate 34 through the opening 13 h of the lid 13, and the flange at the lower end of the cylindrical outer conductor 22 is connected to the periphery of the opening 13 h of the lid 13. Yes. The electrode 36 is provided so as to cover most of the lower surface of the dielectric plate 34 so that only the outer peripheral edge 34p of the dielectric plate 34 is exposed to the sealed space 11. A gap 23 between the inner conductor 21 and the outer conductor 22 of the coaxial tube 20 communicates with the atmosphere. For this reason, in order to seal the sealed space 11, an O-ring 40 having heat resistance is installed between the lower surface of the lid 13 and the dielectric plate 34. For the O-ring 40, a synthetic rubber excellent in heat resistance and plasma resistance, for example, perfluoroelastomer is used. In this apparatus, a microwave introduced from an unillustrated microwave supply source to the inner conductor 21 propagates through the coaxial waveguide 20, passes through the dielectric plate 34, and conducts a conductor surface wave from the outer peripheral edge 34 p of the dielectric plate 34. It propagates along the surface 36f of the electrode 36 as TM. The plasma is excited by the microwave as the conductor surface wave TM propagating on the surface 36f of the electrode 36.

Patent No. 4944198

  In the plasma processing apparatus described above, the O-ring 40 formed of an elastomer having heat resistance is used for sealing the closed space 11. However, since the O-ring 40 is disposed in the microwave path as described above, it is heated to about 200 ° C. during the plasma processing. The O-ring 40 is exposed to oxygen radicals or hydrogen radicals formed by excited plasma under a heated state to cause a chemical reaction, and the gasification substance leaks into the sealed space 11. It was. The gasified substance leaking into the sealed space 11 of the processing chamber 10 is taken into the film on the substrate 16 formed by plasma processing in the processing chamber 10, and there is a problem that the characteristics of the film are affected. .

  The present invention provides a plasma processing apparatus capable of improving the characteristics of a film formed by plasma processing, and a sealing method applied to the plasma processing apparatus.

  The plasma processing apparatus according to the present invention includes a processing chamber that defines a sealed space, a plasma forming electrode provided in the sealed space, and an opening formed in the processing chamber from the outside of the processing chamber. An inner conductor extending toward the forming electrode, surrounding the inner conductor, defining an air gap between the inner conductor and the outer conductor defining the opening; and the inner conductor and the outer conductor A seal member formed of an insulator for connecting the gap to an atmosphere-side space and a space communicating with the sealed space; and, of the gap, the sealed space side with respect to the seal member And a discharge preventing member made of an insulating material that fills the space formed in the substrate.

  According to the sealing method of the present invention, the plasma formation is performed through a processing chamber defining a sealed space, a plasma forming electrode provided in the sealed space, and an opening formed in the processing chamber from the outside of the processing chamber. A plasma processing apparatus sealing method comprising: an inner conductor extending toward an electrode; and an outer conductor that surrounds the inner conductor, defines an air gap between the inner conductor, and defines the opening A seal member formed of an insulator is connected to the inner conductor and the outer conductor, the gap is separated into a space on the atmosphere side and a space communicating with the sealed space, and the seal among the gaps A space formed on the sealed space side with respect to the member is filled with an insulator.

  According to the present invention, since an elastomeric O-ring is not used for sealing in the vicinity of the plasma forming region of the processing chamber, no gasified substance is generated, and the characteristics of the film formed on the substrate by plasma processing are improved. it can. Further, according to the present invention, the discharge prevention member fills the space formed on the sealed space side with respect to the sealing member, so that when the space is decompressed, the discharge is generated between the inner conductor and the outer conductor. As a result, it is possible to stably excite high-density plasma.

1 is a cross-sectional view schematically showing a plasma processing apparatus according to an embodiment of the present invention. The top view seen from the lower surface side of the electrode of FIG. 1 is a cross-sectional view schematically showing a plasma processing apparatus according to an embodiment of the present invention. The expanded sectional view of the principal part of FIG. The perspective view of a conductive elastic member. Sectional drawing of the VI-VI line direction of FIG. Sectional drawing which shows the outline of the plasma processing apparatus which used the elastomer O-ring around the formation area of plasma.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

First Embodiment A plasma processing apparatus 1 (hereinafter referred to as an apparatus 1) shown in FIGS. 1 and 2 is used for various plasma processing such as plasma CVD (Chemical Vapor Deposition). This apparatus 1 has the same basic structure as the plasma processing apparatus described in FIG. That is, the apparatus 1 includes the processing chamber 10, the susceptor 14, the coaxial tube 20, the dielectric plate 34, and the electrode 36 as described in FIG. The present embodiment includes a sealing member 60, sealing metals 70 and 71, and a discharge preventing member 100 in addition to these configurations, but an O-ring 40 that seals between the dielectric plate 34 and the upper lid 13 is not exist.

  The processing chamber 10 is made of a conductive material such as aluminum alloy or stainless steel, and is connected to a reference potential. An exhaust port 20 for exhausting the atmosphere in the processing chamber 10 is provided at the bottom of the processing chamber 10, and an exhaust device such as a vacuum pump (not shown) installed outside the processing chamber 10 is connected to the exhaust port 20. Is done. With this exhaust device, the sealed space 11 is decompressed. An elastomer O-ring 50 is provided between the outer peripheral edge of the lower surface of the upper lid 13 and the upper end portion of the processing chamber 10 to seal between the upper lid 13 and the processing chamber 10. Since this O-ring 50 is sufficiently separated from the plasma formation region, it does not cause a chemical reaction with oxygen radicals or hydrogen radicals formed by the plasma.

  The dielectric plate 34 is formed of a material such as aluminum oxide and is installed on the lower surface of the upper lid 13. The plasma forming electrode 36 is formed of a material such as an aluminum alloy, and is disposed on the lower surface of the dielectric plate 34. Although not shown, the plasma forming electrode 36 is fixed to the upper lid 13 together with the dielectric plate 34 by a fastening member such as a bolt. As shown in FIG. 2, the dielectric plate 34 and the plasma forming electrode 36 have a square outer shape, and are formed so that the dielectric plate 34 is slightly larger than the plasma forming electrode 36. Of 34, only the outer peripheral edge 34 p is exposed to the sealed space 11.

  The processing chamber 10 including the upper lid 13 is formed of a conductive material such as an aluminum alloy and is grounded. The processing chamber 10 defines a sealed space 11 that can be decompressed. The susceptor 14 is made of, for example, aluminum nitride, and electrostatically attracts the substrate 16 to be placed and supplies a power supply unit (not shown) for applying a predetermined bias voltage, and heats the substrate 16 to a predetermined temperature (not shown). Built-in heater.

  The coaxial tube 20 includes a round bar-shaped inner conductor 21 extending toward the electrode 36 and a cylindrical outer conductor 22 surrounding the inner conductor 21, and a microwave (not shown) provided outside the processing chamber 10. Connected to a supply source and receives microwave power. The inner conductor 21 and the outer conductor 22 are made of a low resistance material such as oxygen-free copper. The inner conductor 21 extends to the upper surface of the dielectric plate 34 through the opening 13 h of the lid 13, and the lower end surface of the inner conductor 21 is adjacent to the upper surface of the dielectric plate 34. It is desirable to provide a narrow gap of about 0.2 to 0.4 mm at room temperature between the inner conductor 21 and the dielectric plate 34. This is because the lower end surface of the inner conductor 21 has moved downward due to the thermal expansion of the inner conductor 21, and even if the processing dimensions of the inner conductor 21 vary, the inner conductor 21 pushes down the dielectric plate 34 and the dielectric This is to prevent the plate 34 from being damaged. The flange at the lower end of the outer conductor 22 is connected to the periphery of the opening 13 h of the lid 13. The flange at the lower end of the external conductor 22 is fixed to the lid 13 and both are electrically connected. The opening 13h formed in the lid 13 has an inner diameter that is approximately the same as the inner diameter of the outer conductor 22, and a gap 23 is formed between the inner conductor 21, the outer conductor 22, and the opening 13h. . That is, the opening 13h of the lid 13 defines a part of the gap 23 and constitutes a part of the outer conductor of the present invention. The gap 23 communicates with the atmosphere.

  The seal member 60 is formed in an annular shape, and is disposed in the gap 23 between the inner conductor 21 and the outer conductor 22, and divides the gap 23 into a space communicating with the air space and the sealed space 11. The seal member 60 is formed of an insulator such as aluminum oxide. The space between the inner peripheral portion at the upper end of the seal member 60 and the outer surface of the inner conductor 21 is sealed with a seal metal 70, and the space between the outer peripheral portion at the lower end of the seal member 60 and the inner wall surface of the opening 13f is sealed metal. 71 is sealed. For the seal metals 70 and 71, a metal having a relatively low coefficient of thermal expansion is used. For example, Kovar in which nickel and cobalt are blended with iron, or a nickel-based alloy (trade name: Inconel) containing nickel, iron, chromium, niobium, molybdenum and the like. The seal metal 70 is brazed to the inner conductor 70 and the seal member 60, and the seal metal 71 is brazed to the seal member 60 and welded to the inner wall surface of the opening 13f. The seal metals 70 and 71 are formed in a cylindrical shape in order to secure a certain dimension of the inner conductor 21 in the central axis direction. This is because the members connected to the seal metals 70 and 71 are deformed due to thermal expansion, so that stress repeatedly acts on the seal metals 70 and 71. However, by securing a certain dimension in the central axis direction, This is to prevent the seal metals 70 and 71 from being broken.

  The discharge preventing member 100 is formed in a ring shape, and the diameter of the through hole 100a formed in the center is formed so that the inner conductor 70 is fitted, and the outer peripheral surface 100b on the upper end side is an annular sealing metal 70. The outer peripheral surface 100c on the lower end side is formed so as to fit on the inner wall surface of the opening 13h of the upper lid 13. The height of the discharge preventing member 100 (the dimension of the inner conductor 70 in the central axis direction) is substantially the same as the distance between the lower surface of the seal member 60 and the upper surface of the dielectric plate 34. As described above, the discharge preventing member 100 is formed to have a size that fills the space SP that is a part of the gap 23 defined by the sealing member 60, the sealing metal 71, the inner wall surface of the opening 13h, and the upper surface of the dielectric plate 34. Has been. The discharge prevention member 100 is formed of an insulator, and it is preferable to use a material having low microwave absorption. For example, quartz, aluminum oxide, fluorocarbon resin (trade name: Teflon (registered trademark)) or the like can be used as a material for forming the discharge preventing member 100.

  Here, the operation of the discharge preventing member 100 will be described. The above-described space SP is sealed with respect to the air gap 23 by the seal member 60 and the seal metals 70 and 71 and communicates with the sealed space 11 of the processing chamber 10. When the plasma processing is performed in the processing chamber 10, the sealed space 11 is depressurized and the space SP is also depressurized. In this state, when a strong microwave is supplied to the coaxial tube 20, the microwave is It propagates through the coaxial tube 20, passes through the dielectric plate 34, and propagates from the outer peripheral edge 34p of the dielectric plate 34 along the surface 36f of the electrode 36 as a conductor surface wave TM. The plasma is excited by the microwave as the conductor surface wave TM propagating on the surface 36f of the electrode 36. At this time, since the space SP is in the path of the microwave, abnormal discharge easily occurs in the space SP. When abnormal discharge occurs, microwave power is consumed, so that plasma cannot be normally excited on the surface of the plasma forming electrode 36. In addition, a member existing around a region where abnormal discharge occurs may be heated and damaged. For this reason, in this embodiment, generation | occurrence | production of abnormal discharge is prevented reliably by installing the discharge prevention member 100 in the space SP and filling the space SP. That is, when the seal member 60 and the seal metals 70 and 71 are used in place of the conventional O-ring 40 to seal the opening 13h of the processing chamber 10, the space SP having a certain size becomes a microwave path. Although inevitably formed, by filling this space SP with the discharge preventing member 100, plasma can be excited stably, and damage to the apparatus due to abnormal discharge can be prevented. Furthermore, since the elastomer O-ring 40 is not used, the characteristics of the film formed by the plasma treatment can be improved.

Second Embodiment Next, a plasma processing apparatus according to another embodiment of the present invention will be described with reference to FIGS. 3 to 6, the same reference numerals are used for the same components as those in the first embodiment. In the present embodiment, other aspects of the discharge preventing member and other aspects of the coaxial tube will be described.

  As described above, the abnormal discharge can be prevented by filling the space SP formed above the plasma forming electrode 36 in the sealed gap 23 with the discharge preventing member. However, if the space SP has a complicated shape or is distorted, it may be difficult to fill the space SP with an integrally formed insulator. For this reason, the plasma processing apparatus 1A (hereinafter referred to as apparatus 1A) according to the present embodiment is the first discharge preventing member 100A formed as the discharge preventing member so as to match the shape of the space where the abnormal discharge occurs. In addition, it has the 2nd discharge prevention member 100B formed so that it may have fluidity. 3 and 4, the seal member 60A is connected to the inner conductor 21A by a sealing metal 70A, and is connected to the outer peripheral edge portion of the opening 13h of the upper lid 13 by a sealing metal 71A. The space 23 is separated from the atmosphere side and the electrode 36 side by the seal member 60A and the sealing metals 70A and 71A, and a space communicating with the sealed space 11 is formed on the electrode 36 side. The space SP3 formed between the lower end surface of the seal member 60A and the upper surface of the dielectric plate 34 is formed by the first discharge preventing member 100A made of a dielectric formed in a ring shape so as to match the space SP3. Buried. The second discharge member 100B includes a space SP1 formed between the inner conductor 21A and the inner peripheral surface of the seal member 60A, the seal member 60A, the seal metal 71A, the upper lid 13, and the first discharge prevention member 100A. Is housed in a space SP2 surrounded by

  The second discharge member 100B is a large number of small particles (for example, a spherical shape having a diameter of about 1 mm) formed of aluminum oxide, fluorocarbon resin (trade name: Teflon (registered trademark)), quartz, or the like. Has fluidity. For this reason, it is possible to fill the space according to the shape of the space to be accommodated, and it is not necessary to process the insulator so as to match the shape of the space to be accommodated. The second discharge member 100B is not limited to a granular body, and may be a powder or a liquid. In the case of a liquid, the space may be filled with an insulating liquid having a small dielectric loss in the microwave band, for example, a fluorine-based liquid (trade name: Fluorinert, Galden, etc.).

  Next, the configuration of the coaxial tube will be described. In the first embodiment, a slight gap is formed between the lower end surface of the inner conductor 21 and the upper surface of the dielectric plate 34. When the size of the gap changes due to the temperature change of the inner conductor 21, the load impedance from the coaxial tube 20 side to the electrode 36 changes greatly, and it becomes difficult to control the power supplied to the plasma. In addition, if a gap is formed between the inner conductor and the dielectric plate, abnormal discharge may occur.

  In order to solve the above problem, the apparatus 1A according to the present embodiment is provided with a movable conductor plate 21B between the lower end surface of the inner conductor 21A constituting the coaxial tube 20A and the upper surface of the dielectric plate 34. A conductive elastic member 150 is provided between the plate 21B and the lower end surface of the internal conductor 21A. A sirocco fan 200 for air-cooling the inner conductor 21A is attached to the outer peripheral surface of the cylindrical outer conductor 22 constituting the coaxial pipe 20A.

  The movable conductor plate 21B is formed in a disk shape having substantially the same diameter as the inner conductor 21A, and a ring-shaped groove 21Bt for receiving the conductive elastic member 150 is formed on the upper surface. The movable conductor plate 21B is formed of a low-resistance material such as copper, like the internal conductor 21A. As shown in FIG. 4, a gap Gp is formed between the lower end surface of the inner conductor 21 </ b> A and the upper surface of the movable conductor plate 21 </ b> B by inserting the conductive elastic member 150.

  As shown in FIG. 5, the conductive elastic member 150 is a spring in which a spirally wound wire is formed in a ring shape. The conductive elastic member 150 is made of a metal such as stainless steel or phosphor bronze and has conductivity. Due to the presence of the conductive elastic member 150, the inner conductor 21A and the movable conductor plate 21B are always electrically connected. As the conductive elastic member 150, in addition to the wire material, a belt-shaped spring material is spirally wound to form a ring shape, a flat spring material is processed into a leaf spring, nickel, Those plated with gold, silver or the like can be used. Also, a resin O-ring with metal plating can be used.

  The conductive elastic member 150 pushes down the movable conductor plate 21 </ b> B with an appropriate elastic force and brings the movable conductor plate 21 </ b> B into close contact with the dielectric plate 34. Even if the lower surface of the inner conductor 21A is moved downward due to the thermal expansion of the inner conductor 21A, and even if the processing dimensions vary, the movable conductor plate 21B and the dielectric plate 21B It is possible to prevent a gap from being generated.

  As shown in FIG. 5, an inlet 22h1 for taking in cooling air supplied from the sirocco fan 200 into the outer conductor 22A is provided on the wall surface of the outer conductor 22A to which the exhaust port 201 of the sirocco fan 200 is connected. A plurality of outlets 22h2 for discharging the air from the outer conductor 22A to the outside are formed on the opposite side of the inner conductor 21A on the wall surface of the outer conductor 22A from the inlet 22h1. By introducing the cooling air through the inlet 22h1 into the inner conductor 21A that rises in temperature during the plasma processing, the temperature rise of the inner conductor 21A can be suppressed. Further, by controlling the air volume of the sirocco fan 200, the temperature of the inner conductor 21A can be made substantially constant. If the temperature rise or temperature change of the inner conductor 21A can be suppressed, deformation of the inner conductor 21A due to heat can be suppressed, and the size of the gap Gp between the lower end surface of the inner conductor 21A and the upper surface of the movable conductor plate 21B can be made constant. Can be maintained, and fluctuations in load impedance can be suppressed.

In the above embodiment, the seal member is connected using the seal metal. Is possible.

  In the above embodiment, the sealing member and the discharge preventing member are formed of different materials, but may be formed of the same material. Moreover, although the sealing member and the discharge preventing member are separate members, the sealing member and the discharging preventing member may be integrated to have both a sealing function and a function of filling the space SP.

  In the above-described embodiment, the case where a part of the discharge preventing member is made of an insulator having fluidity has been described. However, the entire discharge preventing member can be made of an insulator having fluidity.

  In the above embodiment, the air cooling mechanism using the sirocco fan is applied to the apparatus of the second embodiment, but this air cooling mechanism can also be applied to the apparatus according to the first embodiment.

  In the above embodiment, the case where microwaves are used as electromagnetic waves has been described, but the present invention is not limited to this, and may be electromagnetic waves in other frequency bands.

  As mentioned above, although embodiment of this invention was described in detail, referring an accompanying drawing, this invention is not limited to this example. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

1, 1A Plasma processing apparatus 10 Processing chamber 13 Lid (external conductor)
13h Opening 14 Susceptor 20, 20A Coaxial tube 21 Inner conductor 22 Outer conductor 34 Dielectric plate 36 Electrode 60 Seal member 70, 71 Metal 100 for seal Discharge prevention member 150 Conductive elastic member 200 Sirocco fan

Claims (4)

A processing chamber defining an enclosed space;
An electrode for plasma formation provided in the sealed space;
An internal conductor extending from the outside of the processing chamber through an opening formed in the processing chamber toward the electrode for plasma formation;
An outer conductor surrounding the inner conductor, defining an air gap with the inner conductor, and defining the opening;
A seal member formed of an insulator, connected to the inner conductor and the outer conductor, for separating the gap into a space on the atmosphere side and a space communicating with the sealed space;
A plasma processing apparatus, comprising: a discharge preventing member made of an insulator that fills a space formed on the sealed space side with respect to the seal member in the gap.   The plasma processing apparatus according to claim 1, wherein the sealing member is connected to the inner conductor and the outer conductor via a sealing metal.   The plasma processing apparatus according to claim 1, wherein at least a part of the discharge preventing member is formed to have fluidity. A processing chamber defining an enclosed space;
An electrode for plasma formation provided in the sealed space;
An internal conductor extending from the outside of the processing chamber through an opening formed in the processing chamber toward the electrode for plasma formation;
A plasma processing apparatus sealing method comprising: an outer conductor surrounding the inner conductor, defining an air gap between the inner conductor and the outer conductor;
A sealing member formed of an insulator is connected to the inner conductor and the outer conductor, and the gap is separated into a space on the atmosphere side and a space communicating with the sealed space;
A sealing method for a plasma processing apparatus, characterized in that, of the gap, a space formed on the sealed space side with respect to the sealing member is filled with an insulator.

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