JP4202292B2 - Plasma processing equipment - Google Patents

Description

  The present invention relates to a plasma processing apparatus that performs processing such as surface modification, cleaning, processing, and film formation by applying plasma generation and control technology, such as semiconductors, liquid crystal display elements, and EL (electroluminescence) panels. The present invention relates to a plasma processing apparatus used in an apparatus for manufacturing flat panel displays such as PDP (Plasma Display Panel) and solar cells.

  Conventionally, in the manufacturing process of semiconductors, flat panel displays, solar cells, etc., plasma generated under reduced pressure is used to modify glass substrates (hereinafter referred to as substrates) and semiconductor wafers (hereinafter referred to as wafers). Processes such as quality, cleaning, processing, and film formation have been performed.

  In recent years, with the intensification of cost competitiveness, attention has been focused on atmospheric pressure plasma technology that does not require large-scale facilities such as a vacuum chamber and an exhaust device. This atmospheric pressure plasma technology is being put into practical use in some processes such as surface modification, cleaning, and dry etching.

  As a typical conventional example of an atmospheric pressure plasma processing apparatus, one described in Patent Document 1 (Japanese Patent Laid-Open No. 7-118857) can be cited. This conventional example will be described with reference to FIG.

  FIG. 13 is a schematic cross-sectional view showing an example of the plasma processing apparatus described in Patent Document 1.

  In FIG. 13, 101 is a power source, 102 is a processing container, 102a is a top surface, 102b is a bottom surface, 102c is a side surface, 102d is an insulator, 103 is a porous metal electrode, 103a is a gas flow path, 103b is an opening, 104 is Metal electrode 105, plasma processing unit 106, first solid dielectric 106, substrate 107, second solid dielectric 108, gas inlet 109, gas inlet 110, gas inlet 110a, 110b Is a gas outlet, 111 is a gas outlet, and 112 is an outlet.

  In this conventional example, a first solid dielectric 106 is provided on one surface of a metal electrode 104, and a porous metal electrode 103 is provided opposite to the first solid dielectric 106, and the porous metal electrode 103 receives a reaction gas. The space between the first solid dielectric 106 and the porous metal electrode 103 is covered with the second solid dielectric 108 between the first solid dielectric 106 and the porous metal electrode 103.

  In this plasma processing apparatus, a substrate 107 is installed in a space covered with a second solid dielectric 108, an inert gas is supplied to the substrate 107, and the substrate 107 reacts with the porous metal electrode 103. Supply gas. Then, under a pressure close to atmospheric pressure, a voltage is applied to the electrode 103 to generate glow discharge plasma, and the active species excited by the plasma are brought into contact with the surface of the substrate 107 to perform surface treatment of the substrate 107. .

  Further, of the electrodes 104 and 103 facing each other, the electrode 104 is a metal electrode 104 having a first solid dielectric 106 disposed on the opposing surface, and the electrode 103 is a porous metal electrode 103 capable of supplying a reaction gas. It is. In addition, this Patent Document 1 further describes that the porous metal electrode and the metal electrode are connected so that one of them is on the anode side and the other is on the cathode side, and the top and bottom may be reversed.

  That is, in the said patent document 1, the following (i)-(vii) is described.

(i) the object to be processed (substrate 107) is placed between the opposing electrodes;
(ii) providing a solid dielectric on at least one opposing surface side of the opposing electrodes;
(iii) supplying a reaction gas between the counter electrodes;
(iv) the reaction gas is supplied through the porous metal electrode;
(v) The voltages applied to the two opposing electrodes have different polarities, but one of them is grounded;
(vi) Glow discharge plasma is generated between two opposing electrodes;
(vii) No glow discharge plasma is generated with a single porous metal electrode or a single metal electrode (plasma is generated only when the electrodes are paired).

  However, the conventional plasma generator has the following problems (a) to (f).

  (a) When the distance between the opposing solid dielectric and the porous metal electrode is increased, the discharge becomes unstable, the discharge is localized, or the discharge itself does not occur.

  (b) In the case of (a) above, if an attempt is made to stabilize the discharge by increasing the applied voltage, the workpiece will be damaged.

  (c) The decomposition of the processing gas is difficult to proceed and the gas utilization efficiency is low.

  (d) It is difficult to realize a flat-flow process in which processing is performed while moving an object to be processed on a predetermined plane, which becomes a large scale when the apparatus is realized.

  (e) When the distance between the opposing solid dielectric and the porous metal electrode is reduced, processing unevenness due to the aperture pattern of the porous metal electrode occurs.

(f) It is difficult to adjust the distance between the opposing solid dielectric and the porous metal electrode.
Japanese Patent Laid-Open No. 7-118857

  SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma processing apparatus capable of generating stable plasma with a wide work distance control range under atmospheric pressure and achieving both low running cost and high speed processing. Furthermore, it is providing the safe and cheap plasma processing apparatus which eliminated the obstacle with respect to a peripheral device or a human body.

In order to solve the above problems, a plasma processing apparatus of the present invention includes a gas supply unit that supplies a predetermined processing gas to a plasma processing space in which an object to be processed is disposed,
A first electrode facing the plasma processing space and generating an electric field in the plasma processing space;
An electric field is formed in the plasma processing space by facing the plasma processing space, facing the first electrode across the plasma processing space, and forming an electric field with the first electrode. A second electrode for converting the processing gas into plasma,
The processing gas is opposed to the side surface of the first electrode adjacent to the facing surface of the first electrode facing the plasma processing space with a predetermined gap and an electric field is formed in the predetermined gap. A third electrode for converting to plasma;
A first power supply unit for supplying first power to the first electrode,
The opposing surface and the side surface of the first electrode are connected by a convex curved surface ,
The facing surface of the first electrode is a flat surface facing the plasma processing space, and the second electrode has a flat surface facing the flat surface of the first electrode,
After the processing gas supplied by the gas supply unit passes through the gap between the side surface of the first electrode and the third electrode, the processing gas between the first electrode and the second electrode is used. A structure that passes through the plasma processing space,
Furthermore, the third electrode is grounded,
The first power supplied to the first electrode and the second power supplied to the second electrode are characterized in that at least one of phase or amplitude is different .

  In the plasma processing apparatus of the present invention, the first electrode is supplied with the first power from the first power supply unit, and an electric field is formed between the first electrode and the second electrode. The above electric field is formed. On the other hand, the gas supply unit supplies a processing gas to the plasma processing space. As a result, the processing gas is turned into plasma by the electric field formed in the plasma processing space under atmospheric pressure. The object to be processed disposed in the plasma processing space is subjected to plasma processing by the plasma processing gas.

  At this time, an electric field is also formed between the side surface of the first electrode and the third electrode, and the process existing between the side surface of the first electrode and the third electrode is caused by this electric field. The gas is turned into plasma. That is, the space between the side surface of the first electrode and the third electrode becomes a preliminary discharge region, and the plasma generated in the preliminary discharge region is between the plasma processing space and the first electrode. When reaching this region, electrons and excited species are directly supplied to the plasma processing space by the plasma. Here, this phenomenon is called creeping discharge.

  In this way, by generating plasma in the preliminary discharge region, electrons and excited species are directly supplied to the plasma processing space. Therefore, when plasma is not generated in the plasma processing space, The discharge start can be assisted, and the discharge can be stabilized when the discharge is being performed in the plasma processing space.

  According to the present invention, the following effects (I) to (VI) can be expected by utilizing the creeping discharge.

  (I) The control range of the work distance between the first electrode and the second electrode can be expanded.

  (II) Since the processing gas is decomposed in the preliminary discharge region in addition to the plasma processing space, the utilization efficiency of the processing gas is increased.

  (III) Compared with the conventional plasma generator, the plasma can be maintained even if the electric field in the plasma processing space is weakened. As a result, damage to the object to be processed can be reduced.

  (IV) The equipment becomes compact and flat flow treatment becomes easy.

  (V) By arranging the gas supply unit on the back side of the first electrode and supplying a processing gas to a preliminary discharge region between the side surface of the first electrode and the third electrode, Since the gas outlet of the gas supply section can be separated from the plasma processing space, processing unevenness due to the opening pattern of the gas outlet is less likely to occur.

  (VI) It becomes easy to adjust the distance between the first electrode and the second electrode.

  Therefore, according to the present invention, it is possible to generate a stable plasma with a wide work distance control range under atmospheric pressure, and to realize a plasma processing apparatus that can achieve both low running cost and high speed processing.

The plasma processing apparatus according to an embodiment includes a first dielectric portion that covers the facing surface and the side surface of the first electrode,
A second dielectric portion covering the side surface of the third electrode facing the side surface of the first electrode,
The first dielectric part and the second dielectric part are opposed to each other with a predetermined gap.

  In this embodiment, the first electrode is provided with the first dielectric portion that covers the opposing surface and the side surface of the first electrode, and the second dielectric portion that covers the side surface of the third electrode. And the third electrode can be prevented from being damaged by discharge.

In the plasma processing apparatus of one embodiment, the third electrode is grounded,
A second power supply unit that supplies the second power to the second electrode;
The first power supplied from the first power supply unit to the first electrode and the second power supplied from the second power supply unit to the second electrode are at least in phase or amplitude. One is different,
The first power and the second power are:
It is high frequency power, pulse wave power, power obtained by switching high frequency power and pulse wave power, or power obtained by superimposing high frequency power and pulse wave power.

  In this embodiment, in consideration of various conditions required for plasma processing, types of processing gas, required processing capacity, and electromagnetic interference with peripheral devices and safety with respect to the human body, the first and second powers are used. Is selected from high-frequency power, pulse-wave power, power obtained by switching high-frequency power and pulse-wave power, or power obtained by superimposing high-frequency power and pulse-wave power. . Here, the high frequency power refers to power having a frequency of 1 kHz or more and 100 MHz or less. The pulse power means that the repetition frequency is 1 MHz or less, the waveform rise time is 100 μs, and the pulse application time is 1 millisecond or less.

  In one embodiment, the processing gas supplied by the gas supply section passes through the gap between the side surface of the first electrode and the third electrode, and then the first gas The structure passes through the plasma processing space between the electrode and the second electrode.

  In this embodiment, the gas supply unit is disposed on the back side of the first electrode, and the process gas is supplied to the preliminary discharge region between the side surface of the first electrode and the third electrode. The gas outlet of the supply unit can be separated from the plasma processing space. Therefore, the process nonuniformity resulting from the opening pattern of the gas ejection port is less likely to occur.

  In the plasma processing apparatus of one embodiment, the gas supply unit includes a gas jet for supplying the processing gas to the gap between the first electrode and the third electrode, and the gas jet An opening control unit that changes at least one of the opening area or the opening shape is provided.

  In this embodiment, the gas supply unit can control the gas flow rate and the gas flow rate by changing at least one of the opening area or the opening shape of the gas ejection port with the opening control unit. As a result, the flow rate and flow rate of the processing gas supplied to the plasma processing space can be controlled.

  In one embodiment, the plasma processing apparatus includes a dielectric film formed on the opposing surface and the side surface of the first electrode, and the first dielectric portion covers the dielectric film. Yes.

  In this embodiment, since the dielectric film is formed on the facing surface and the side surface of the first electrode, the first dielectric portion is made as an independent component separate from the first electrode. Even when the first dielectric portion is covered with the dielectric coating, a gap (space) generated between the first electrode and the first dielectric portion can be minimized. Therefore, it is possible to suppress a decrease in electric field strength in the plasma processing space and the preliminary discharge region, and it is possible to suppress the discharge in the gap and suppress the occurrence of power loss and electrode damage.

  In one embodiment, the gap between the first electrode and the first dielectric portion is 500 μm or less.

  In this embodiment, since the gap between the first electrode and the first dielectric portion is set to 500 μm or less, the effect of suppressing a decrease in electric field strength and the effect of suppressing a discharge in the gap are exhibited. it can. When the gap exceeds 500 μm, the effect of the suppression becomes insufficient. The gap between the first electrode and the first dielectric part is more preferably 100 μm or less.

  According to this invention, in addition to the plasma processing space between the first electrode and the second electrode, an electric field can be formed between the side surface of the first electrode and the third electrode. The processing gas existing between the side surface of the first electrode and the third electrode can be converted into plasma. Therefore, according to the present invention, the space between the side surface of the first electrode and the third electrode is used as a preliminary discharge region, and electrons and excited species generated by the plasma generated in the preliminary discharge region are directly input to the plasma processing space. Can supply.

  Therefore, plasma is easily generated in the plasma processing space and plasma discharge can be stabilized, so that stable plasma with a wide work distance control range can be generated under atmospheric pressure, with low running cost and high speed processing. Can be realized.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

(First embodiment)
FIG. 1 shows a first embodiment of the plasma processing apparatus of the present invention. FIG. 1 is a side cross-sectional view showing a cross section of the plasma processing apparatus cut along a plane that is perpendicular to the plate-like workpiece 14 and includes a line segment extending in the direction in which the workpiece 14 is conveyed. . FIG. 2 is an enlarged view of FIG. 1 showing the main part of the plasma processing apparatus. The workpiece 14 is a semiconductor substrate as an example.

  As shown in FIGS. 1 and 2, the plasma processing apparatus includes a chamber upper portion 1, a chamber lower portion 2, an upper electrode unit 3, and a lower electrode unit 4. The chamber upper portion 1 and the chamber lower portion 2 constitute a chamber C. The chamber C has entrances 17a and 17b for the workpiece 14 between the chamber upper portion 1 and the chamber lower portion 2 at both ends in the transport direction.

  The upper electrode unit 3 is fitted into an opening formed in the approximate center of the chamber upper portion 1 and is covered with an upper electrode cover 12. The upper electrode cover 12 has a gas supply port 21-1 communicating with the upper electrode unit 3.

  In addition, the lower electrode unit 4 is disposed at substantially the center of the lower chamber portion 2 and faces the upper electrode unit 3 with a predetermined interval. On both sides of the lower electrode unit 4, a conveying roller 13 supported by a roller shaft 23 is disposed. Further, a conveying roller 13 is also disposed outside the side walls 2a and 2b of the chamber lower portion 2. The workpiece 14 can be transported in the transport direction on a predetermined plane by the transport roller 13. The chamber lower part 2 has a gas supply port 21-2 communicating with the lower electrode unit 4. The lower chamber portion 2 has two exhaust ports 22 penetrating on both sides of the lower electrode unit 4.

  As shown in FIG. 3, the upper electrode unit 3 includes a main electrode 5 as a first electrode disposed at the center, and a side surface 6B-1 facing the side surfaces 5B-1 and 5B-2 of the main electrode 5. , 6B-2 and the side electrode 6 as a third electrode. The main electrode 5 and the side electrode 6 are made of metal.

  The main electrode 5 is covered with a first dielectric part 7-1 made of a solid dielectric, and the first dielectric part 7-1 is composed of an opposing surface 5C and a side surface 5B-1 of the main electrode 5. , 5B-2 and the back surface 5D. In the side electrode 6, the end 6C including the side surfaces 6B-1 and 6B-2 is covered with a second dielectric part 8-1 made of a solid dielectric. The first dielectric part 7-1 and the second dielectric part 8-1 are opposed to each other with a predetermined gap, and this gap serves as a preliminary discharge region 16-1.

  As shown in FIG. 3, the preliminary discharge region 16-1 communicates with a gas flow channel 26-1 formed in the base portion 6 </ b> D of the side electrode 6. The first dielectric portion 7-1 is fixed to a portion 6E adjacent to the gas flow path 26-1 in the base portion 6D of the side electrode 6. As shown in FIG. 2, the side electrode 6 has a gas reservoir 9-1 formed of a concave portion opened upward, and the gas reservoir 9-1 is connected to the gas flow path 26-1 and the gas supply port 21-1. Communicate. The gas reservoir 9-1, the gas flow path 26-1, and the gas supply port 21-1 constitute a gas supply unit G1. Further, the gas flow path 26-1 forms a gas outlet 11-1 for supplying a processing gas to the preliminary discharge region 16-1.

  As shown in FIG. 3, flow rate adjusting plates 35-1 and 35-1 serving as opening control units are slidably arranged in the left-right direction at a portion 6 E of the base 6 D of the side electrode 6. The flow rate adjusting plates 35-1 and 35-1 are slid to the left and right to change the opening area and the opening shape on the inflow side of the gas flow path 26-1.

  Further, the side electrode 6 is formed with a through hole 6A, and the side electrode 6 is cooled by circulating the coolant 10 through the through hole 6A. The main electrode 5 is also provided with a through hole 5A, and the main electrode 5 is cooled by circulating the coolant 10 through the through hole 5A.

  The main electrode 5 that is the first electrode is connected to a high-frequency power source 18 that is a first power supply unit through a power transmission path 27, and the high-frequency power source 18 is connected to the ground. Further, the side electrode 6 is grounded by an electric circuit 28.

  On the other hand, as shown in FIG. 3, the lower electrode unit 4 has substantially the same structure as the upper electrode unit 3, and a main electrode 31 as a second electrode disposed at the center, and a side surface of the main electrode 31. A side electrode 32 is provided as a third electrode having side surfaces 32B-1 and 32B-2 opposite to 31B-1 and 31B-2. The main electrode 31 and the side electrode 32 are made of metal.

  The main electrode 31 is covered with a first dielectric part 7-2 made of a solid dielectric, and the first dielectric part 7-2 is composed of an opposing surface 31 </ b> C and a side surface 31 </ b> B- 1 of the main electrode 31. , 31B-2 and the back surface 31D. In the side electrode 32, the end portion 32C including the side surfaces 32B-1 and 32B-2 is covered with a second dielectric portion 8-2 made of a solid dielectric. The first dielectric part 7-2 and the second dielectric part 8-2 are opposed to each other with a predetermined interval, and this gap serves as a preliminary discharge region 16-2.

  The preliminary discharge region 16-2 communicates with a gas flow path 26-2 formed in the base portion 32D of the side electrode 32. Further, the first dielectric portion 7-2 is fixed to a portion 32E adjacent to the gas flow path 26-2 in the base portion 32D of the side electrode 32. This side electrode 32 has a gas reservoir 9-2 formed of a recess opening downward, and this gas reservoir 9-2 communicates with the gas flow path 26-2 and the gas supply port 21-2. The gas reservoir 9-2, the gas flow path 26-2, and the gas supply port 21-2 constitute a gas supply unit G2. Further, the gas flow path 26-2 forms a gas outlet 11-2 for supplying a processing gas to the preliminary discharge region 16-2.

  As shown in FIG. 3, flow rate adjustment plates 35-2 and 35-2 serving as opening control portions are slidably arranged in the left-right direction at a portion 32 E of the base portion 32 D of the side electrode 32. The flow rate adjusting plates 35-2 and 35-2 are slid to the left and right to change the opening area and the opening shape on the inflow side of the gas flow path 26-2.

  Further, the side electrode 32 has a through hole 32A, and the side electrode 32 is cooled by circulating the coolant 10 through the through hole 32A. The main electrode 31 also has a through hole 31A, and the side electrode 31 is cooled by circulating the coolant 10 through the through hole 31A.

  As shown in FIG. 1, the main electrode 31 is connected to a high frequency power source 33 through a power transmission path 29, and the high frequency power source 33 is connected to the ground. Further, the side electrode 32 is grounded by the electric circuit 30.

  The distance between the main electrode 5 and the main electrode 31 is the magnitude and frequency of power supplied from the high-frequency power sources 18 and 33, the type and flow rate of the processing gas, and the solid that forms the dielectric parts 7-1 and 7-2. It is set based on the electrical characteristics, secondary electron emission coefficient and thickness of the dielectric, the temperature of each part, and the like.

  FIG. 12 is a perspective view of the plasma processing apparatus according to the first embodiment. As shown in FIG. 12, chamber side members 25 are attached to the side end surfaces of the chamber upper portion 1 and the chamber lower portion 2. A plurality of transfer rollers 13 are also arranged outside the chamber lower part 2 so that the plate-like object 14 can be transferred on a predetermined plane passing through the plasma processing space 15.

  In the plasma processing apparatus having the above-described configuration, high-frequency power is supplied to the main electrode 5 that is the first electrode as the first power output from the high-frequency power source 18 that is the first power supply unit via the power transmission path 27. Supplied. Further, high frequency power is supplied to the main electrode 31 that is the second electrode from the high frequency power supply 33 that is the second power supply unit as the second power via the power transmission path 29. Thus, an electric field is formed between the main electrode 5 and the main electrode 31, thereby forming the electric field in the plasma processing space 15. In this embodiment, the high-frequency power output from the high-frequency power source 18 and the high-frequency power output from the high-frequency power source 33 have the same frequency but different phases.

  On the other hand, the gas supply port 21-1 of the gas supply part G1 of the upper electrode unit 3 is supplied with a processing gas in which a plurality of gas types are mixed by a mass flow and a mixer (not shown) from a gas supply cylinder or a gas supply tank (not shown). The As shown in FIG. 2, the processing gas is supplied from the gas supply port 21-1 to the gas reservoir 9-1 and spreads in the depth direction of the paper surface in the gas reservoir 9-1, and is sufficiently larger than the gas reservoir 9-1. It reaches a slit-shaped (or shower-hole-shaped) gas flow path 26-1 having a narrow sectional area. When the processing gas passes through the gas flow path 26-1, the flow velocity is increased, and the processing gas is ejected toward the workpiece 14 through the gas outlet 11-1 and the preliminary discharge region 16-1, and the plasma processing space. 15 is supplied. Similarly, a processing gas is supplied from the gas supply port 21-2 of the gas supply part G2 of the lower electrode unit 4, and this processing gas is a gas reservoir 9-2, a gas flow path 26-2, a gas jet port 11-2, It is supplied to the plasma processing space 15 via the preliminary discharge region 16-2.

  In this way, the processing gas introduced into the plasma processing space 15 from the upper electrode unit 3 and the lower electrode unit 4 is turned into plasma under atmospheric pressure by the electric field formed in the plasma processing space 15. The processing object 14 transported and arranged in the plasma processing space 15 is subjected to plasma processing by the plasma processing gas. Here, as an example, the atmospheric pressure refers to a pressure range of 0.1 atm or more and 2 atm or less. As the processing gas employed in this embodiment, for example, helium, argon, oxygen, air, or the like is employed when surface modification of the workpiece 14 is performed. It is necessary to select an optimal combination and mixing ratio as appropriate.

  Then, the processing gas that has passed through the plasma processing space 15 temporarily accumulates in the exhaust-side gas reservoir 20 shown in FIG. 1, passes through the exhaust port 22, and is rendered harmless by an unillustrated exhaust pump or blower, and in some cases, an abatement device. After that, it is discharged out of the system.

  In this embodiment, an electric field is also formed between the side surfaces 5B-1 and 5B-2 of the main electrode 5 and the side surfaces 6B-1 and 6B-2 of the side electrode 6 in the upper electrode unit 3. By this electric field, the first dielectric part 7-1 covering the side surfaces 5B-1 and 5B-2 of the main electrode 5 and the second dielectric part 8-1 covering the side electrode 6 (that is, the preliminary discharge region). The processing gas existing in 16-1) is turned into plasma. Similarly, in the lower electrode unit 4, an electric field is also formed between the side surfaces 31B-1 and 31B-2 of the main electrode 31 and the side surfaces 32B-1 and 32B-2 of the side electrode 32. This electric field causes a gap between the first dielectric part 2-2 covering the side surfaces 31B-1 and 31B-2 of the main electrode 31 and the second dielectric part 2-2 covering the side electrode 32 (that is, a preliminary discharge region). The processing gas existing in 16-2) is turned into plasma.

  Here, the plasma formation in the preliminary discharge regions 16-1 and 16-2 occurs between the first dielectric parts 7-1 and 7-2 and the second dielectric parts 8-1 and 8-1. This is achieved by selecting an appropriate distance. This distance includes the power and frequency applied to the main electrodes 5 and 31 by the high-frequency power sources 18 and 33, the type and flow rate of the processing gas, and the first and second dielectric parts 7-1, 7-2, 8-1, 8 It is determined by -2 electrical characteristics, secondary electron emission coefficient, thickness and temperature. In this embodiment, the electric field strength formed in the preliminary discharge regions 16-1 and 16-2 is set to be stronger than the electric field formed in the plasma processing space 15.

  In this embodiment, the plasma generated in the preliminary discharge regions 16-1 and 16-2 reaches the creeping discharge portion 24 of the first dielectric portions 7-1 and 7-2, and the plasma processing space 15 Directly, electrons and excited species are supplied (creeping discharge). The creeping discharge portion 24 exists between the main electrodes 5 and 31 and the plasma processing space 15.

  Thus, by generating plasma in the preliminary discharge regions 16-1 and 16-2, electrons and excited species can be directly supplied to the plasma processing space 15. Thereby, when plasma is not generated in the plasma processing space 15, the start of discharge in the plasma processing space 15 can be assisted, and when discharging is in the plasma processing space 15, the discharge can be stabilized. This effect can be further enhanced by eliminating the edge of the creeping discharge portion 24 and making it smooth. As an example, when the corner portion of the creeping discharge portion 24 is curved, it is desirable that the radius of curvature is 0.5 mm or more.

  By utilizing the creeping discharge, the following effects (I) to (VI) can be expected.

  (I) The control range of the work distance between the main electrode 5 and the main electrode 31 can be expanded.

  (II) Since the processing gas is decomposed in the preliminary discharge regions 16-1 and 16-2 in addition to the plasma processing space 15, the utilization efficiency of the processing gas is increased.

  (III) Plasma can be maintained even if the electric field in the plasma processing space 15 is weakened as compared with the conventional plasma generator, and as a result, damage to the workpiece 14 can be reduced.

  (IV) The equipment becomes compact and flat flow treatment becomes easy.

  (V) The gas supply parts G1 and G2 are arranged on the back surfaces 5D and 31D side of the main electrodes 5 and 31, and the preliminary discharge regions 16-1 and 16- between the main electrodes 5 and 31 and the side electrodes 6 and 32 are arranged. 2, the gas jets 11-1 and 11-2 of the gas supply units G <b> 1 and G <b> 2 are separated from the plasma processing space 15. Therefore, the process nonuniformity resulting from the opening pattern of the gas ejection ports 11-1 and 11-2 is less likely to occur.

  (VI) It becomes easy to adjust the distance between the main electrode 5 and the main electrode 31.

  Thus, in this embodiment, when the plasma is generated in both the plasma processing space 15 and the preliminary discharge regions 16-1 and 16-2, the transfer roller 13 is rotated to transfer the object 14 to be processed. Then, plasma is brought into contact with the surface of the workpiece 14. As a result, plasma treatment such as surface modification, cleaning, processing, film formation, etc. progresses due to the reaction promoting effect by active species and the physical etching effect by ions, so that a desired treatment can be performed on the workpiece 14. it can.

  Therefore, according to this embodiment, it is possible to generate a stable plasma having a wide work distance control range under atmospheric pressure, and to realize a plasma processing apparatus that can achieve both low running cost and high-speed processing.

  In this embodiment, the transport roller 13 is used for transporting the workpiece 14. However, this is an example, and a transport holder may be used for transport. Further, local plasma processing may be performed on an object to be processed without performing conveyance during the plasma processing. Further, pulse power sources 19 and 34 may be employed instead of the high frequency power sources 18 and 33.

  Further, according to this embodiment, the first dielectric portion 7-1 covering the opposing surface 5C and the side surfaces 5B-1 and 5B-2 of the main electrode 5, and the side surfaces 6B-1, 6B- of the side electrode 6 are provided. Since the second dielectric portion 8-1 covering the end portion 6C including 2 is provided, the main electrode 5 and the side electrode 6 can be prevented from being damaged by the discharge. Similarly, a first dielectric portion 7-2 covering the opposing surface 31C and the side surfaces 31B-1, 31B-2 of the main electrode 31, and an end portion 32C including the side surfaces 32B-1, 32B-2 of the side electrode 32. Since the second dielectric portion 8-2 is covered, the main electrode 31 and the side electrode 32 can be prevented from being damaged by discharge.

  Further, in this embodiment, the gas supply units G1 and G2 have the flow area adjustment plates 35-1 and 35-2 forming the opening control unit so that the opening area and the opening shape of the gas outlets 11-1 and 11-2 are the same. The gas flow rate and gas flow rate can be controlled. Accordingly, the flow rate and flow rate of the processing gas supplied to the plasma processing space 15 can be controlled.

  In this embodiment, in the upper electrode unit 3 and the lower electrode unit 4, the main electrodes 5 and 31 are covered with the first dielectric parts 7-1 and 7-2, and the side electrodes 6 and 32 are covered with the second dielectric part. Covered with 8-1 and 8-2. The first and second dielectric parts 7-1, 7-2, 8-1 and 8-1 are subjected to thermal spraying or anodic oxidation on the main electrodes 5 and 31 and the side electrodes 6 and 32, so that You may form directly on the surface of the electrodes 5 and 31 and the side electrodes 6 and 32. FIG. However, from the viewpoint of labor and cost during maintenance, the first dielectric parts 7-1 and 7-2 and the second dielectric parts 8-1 and 8-2 are connected to the main electrodes 5 and 31 and the side electrodes 6 and 32. However, it is preferable that the parts can be replaced as independent parts. Note that the thicknesses of the first dielectric parts 7-1 and 7-2 and the second dielectric parts 8-1 and 8-1 are the repetition frequency of the high-frequency power supplies 18 and 33 (or the pulse power supplies 19 and 34), and the processing. This value is determined in close relation to the type of gas and the material properties of the dielectric itself. Therefore, it is difficult to determine the above values in general, but as a general example, the first dielectric parts 7-1 and 7-2 and the second dielectric parts 8-1 and 8-1 are independent parts. The thicknesses of the first dielectric parts 7-1 and 7-2 and the second dielectric parts 8-1 and 8-1 are preferably usually 5 mm or less. In particular, when the power supply frequency is 1 MHz or more, it is more preferably 2 mm or less.

  Further, as the thickness of the first and second dielectric portions 7-1, 7-2, 8-1, 8-1 is reduced, the plasma processing space 15 and the preliminary discharge regions 16-1, 16-2 are reduced. While the electric field strength can be increased, it is weak in strength and easily damaged. For this reason, it is preferable that the said thickness is the range of 0.5 mm or more and 5 mm or less practically. However, when the first and second dielectric parts 7-1, 7-2, 8-1, and 8-1 are not separate parts, the thickness may be made thinner than the above range.

  Moreover, the said embodiment has the same length as the to-be-processed object 14 or more in the paper surface depth direction of FIG. In practice, the above embodiment desirably has a structure that is at least about 20% longer than the length of the workpiece 14 in the depth direction of FIG.

  Moreover, in the said embodiment, the refrigerant | coolant 10 is supplied from the refrigerant | coolant supply apparatus or refrigerant | coolant supply facility which is not illustrated, passes through each part, such as the main electrode 5 and the side electrode 6, and is discharged | emitted. This refrigerant 10 can be used not only for the purpose of cooling the electrodes, but also for maintaining the temperature of each part of the apparatus constant.

  Moreover, in the said embodiment, the chamber upper part 1 and the chamber lower part 2 support the upper electrode unit 3 and the lower electrode unit 4, and are able to set the interelectrode gap between the main electrode 5 and the main electrode 31 so that it can be set. A gap adjusting and holding mechanism (not shown) including a meter head and the like is included. In addition, the chamber upper portion 1 and the chamber lower portion 2 play a role of storing the processing gas until the used processing gas is discharged from the exhaust port 22 so as not to leak outside.

  That is, the chamber C has an airtight structure in which gas does not leak except at locations where the workpiece 14 enters and exits through the entrances 17a and 17b and the exhaust port 22. Further, depending on the processing process and the type of processing gas to be used, the entrance / exit 17a, 17b of the workpiece 14 may have a curtain mechanism or a shutter mechanism for the inert gas.

  In the above-described series of plasma processing steps, it is important to stably generate plasma and increase the utilization efficiency of the processing gas in order to reduce the processing capacity and running cost of the process. In order to achieve this, it is necessary not only to effectively supply the gas to the plasma processing space 15 but also to adjust the gas exhaust and appropriately control the flow rate and flow rate of the processing gas.

  For this purpose, in addition to a mechanism for adjusting the conductance (ease of gas flow) on the supply side, such as the flow rate adjustment plates 35-1 and 35-2 as shown in FIG. In consideration of the conductance of the upper chamber portion 1 and the lower chamber portion 2, it is necessary to balance supply and exhaust.

  In this case, it is simple and practical to determine the dimensions of each part based on the following concept.

That is, the effective sectional area of the gas flow path is S (m ² ), and the length (distance) of the gas flow path is L (m). Since the gas flow under atmospheric pressure is a viscous flow, these parameters and the conductance U, which is an index of the ease of gas flow, have the following relationship (1) when the depth direction is infinite. .

U = a · S ² / L (1)
a: Constant determined by gas type viscosity coefficient and pressure For power supply, in addition to the high-frequency power source 18, a pulse power source 19, or switching between the two, or a method of superimposing both, can be considered. In addition, it is desirable to determine from the viewpoints of various conditions required for the process, restriction of gas used, required processing capacity, and occurrence of damage.

  The high-frequency power source here refers to one having a frequency of 1 KHz to 100 MHz, for example, and the pulse power source has a repetition frequency of 1 MHz or less, a waveform rise time of 100 μsec or less, and a pulse application time of 1 msec or less. Refers to things.

  The flow rate adjusting plates 35-1 and 35-2 shown in FIG. 3 show the case where the gas outlets 11-1 and 11-2 are slit-shaped, but they may be shower-hole shaped. Here, the case where the gas outlets 11-1 and 11-2 have the same opening pattern in the upper and lower electrode units 3 and 4 is shown. However, the present invention is not limited to this combination. Needless to say, all combinations of apertures are possible.

  In place of the flow rate adjusting plates 35-1, 35-2 as the opening control portion shown in FIG. 3, as shown in FIG. 4, the flow rate adjusting cams 43-1 and 42-2 having an elliptical cross section. May be provided in the opening on the inflow side of the gas flow path 26-1. By rotating these cams 43-1 and 42-2 by a predetermined angle around the central axis, the cross-sectional area of the inflow side opening of the gas passage 26-1 can be continuously changed.

  Next, in FIG. 5, the high frequency voltage waveform 36 given to the main electrode 5 by the high frequency power source 18 is shown by a solid line, and the high frequency voltage waveform 37 given by the high frequency power source 33 to the main electrode 31 is shown by a broken line. In the example shown in FIG. 5, the phases of the high-frequency voltage waveforms 36 and 37 are shifted by π. In this case, the potential difference generated between the main electrode 5 and the main electrode 31 is the sum (V1 + V2) of the amplitude V1 of the high-frequency voltage waveform 36 and the amplitude V2 of the high-frequency voltage waveform 37. Further, the potential difference generated between the main electrode 5 and the side electrode 6 is V1.

  FIG. 6 shows an example of a pulse waveform given to the main electrode 5 by the pulse power source 19 in the case where pulse power sources 19 and 34 are provided instead of the high frequency power sources 18 and 33, and is indicated by a solid line denoted by reference numeral 38. An example of a pulse waveform that the power source 34 gives to the main electrode 31 is indicated by a broken line denoted by reference numeral 39. In the example shown in FIG. 6, the phases of the pulse waveforms 38 and 39 are shifted by π.

  FIG. 7 shows an example of a waveform when the pulse power source 19 gives a DC pulse waveform to the main electrode 5 by a solid line indicated by reference numeral 40, and a waveform when the pulse power source 34 gives a DC pulse waveform to the main electrode 31. An example is shown by a broken line denoted by reference numeral 41.

  In the example shown in FIGS. 5 to 7, an example is shown in which the phase difference between the voltage waveform applied to the main electrode 5 and the voltage waveform applied to the main electrode 31 is π, but this phase difference is other than π. Also good. Each voltage waveform applied to the main electrodes 5 and 31 may be a waveform formed by switching between a high frequency waveform and a pulse waveform, or may be a waveform in which a high frequency waveform and a pulse waveform are superimposed.

  Moreover, in the said embodiment, in the upper electrode unit 3 and the lower electrode unit 4, the main electrodes 5 and 31 are arrange | positioned in the center, and the side electrodes 6 and 32 are arrange | positioned on both sides, However, It is not limited to this arrangement | positioning. Instead, the side electrode that is the ground electrode may be disposed only on one side of the main electrode, or a plurality of side electrodes may be disposed on one side of the main electrode. Further, a plurality of side electrodes may be arranged on both sides of the main electrode.

( Reference example )
Next, FIG. 8 shows a reference example of the plasma processing apparatus of the present invention. This reference example differs from the first embodiment in that a lower electrode unit 50 is provided instead of the lower electrode unit 4. The lower electrode unit 50 is connected to the ground by the electric circuit 30.

  The lower electrode unit 50 has a main electrode 51, and a tip 51 </ b> A of the main electrode 51 is covered with a dielectric part 53. The front end portion 51 </ b> A has a facing surface 51 </ b> C facing the facing surface 5 </ b> C of the main electrode 5.

FIG. 9 shows an example of a high-frequency voltage waveform applied to the main electrode 5 by the high-frequency power source 18 by reference numeral 42. The basic operation of the second embodiment is the same as that of the first embodiment except that the lower electrode unit 50 is grounded. This reference example is suitable when there is no need to process the back surface 14A of the object 14 to be processed, and has the advantage that the amount of gas used is small and the control of the power supply is simplified.

(Second Embodiment)
Next, FIG. 10 shows a second embodiment of the plasma processing apparatus of the present invention. The second embodiment is different from the first embodiment in that a dielectric sprayed film 61 is formed on the surface of the main electrode 5 and a dielectric sprayed film 62 is formed on the surface of the main electrode 31. The first dielectric part 7-1 covers the dielectric sprayed film 61, and the first dielectric part 7-2 covers the dielectric sprayed film 62.

In the second embodiment, since the dielectric film 61 is formed on the opposing surface 5C and the side surfaces 5B-1 and 5B-2 of the main electrode 5, the first dielectric portion 7-1 is different from the main electrode 5. Even when the first dielectric part 7-1 is covered with the dielectric coating 61 as a separate and independent part, a gap (space) generated between the main electrode 5 and the first dielectric part 7-1. Can be minimized. Further, since the dielectric film 62 formed on the opposing surface 31C and the side surfaces 31B-1 and 31B-2 of the main electrode 31 is provided, the first dielectric portion 7-2 is separated from the main electrode 31 independently. Even when the first dielectric part 7-2 is covered with the dielectric film 62 as a component, the gap (space) generated between the main electrode 31 and the first dielectric part 7-2 is minimized. It becomes possible.

  Therefore, according to this embodiment, it is possible to suppress a decrease in electric field strength in the plasma processing space 15 and the preliminary discharge regions 16-1 and 16-2, and it is possible to suppress discharge in the gap and cause power loss and electrode damage. This can be suppressed. In addition, it is preferable that the said clearance gap is 500 micrometers or less, More preferably, it is 100 micrometers or less.

( Third embodiment)
Next, FIG. 11 shows a third embodiment of the plasma processing apparatus of the present invention. The third embodiment includes a chamber D composed of a chamber upper portion 71 and a chamber lower portion 72 instead of the chamber C composed of the chamber upper portion 1 and the chamber lower portion 2, and the chamber D includes two upper electrode units 3 and two The point provided with the lower electrode unit 4 differs from the first embodiment described above. The main electrodes 6 and 6 of the two upper electrode units 3 and 3 are connected to the high-frequency power source 18 through power transmission paths 27-1 and 27-2, respectively, and the side electrodes 6 and 6 are connected to the electrical paths 28-1 and 28-2, respectively. Connected to ground. The main electrodes 31, 31 of the two lower electrode units 4, 4 are connected to a high frequency power source 33 through a power transmission path 29. Further, the side electrodes 32, 32 are connected to the ground by an electric circuit 30.

In the third embodiment, since a plurality of sets of the upper electrode unit 3 and the lower electrode unit 4 are provided, the processing capability can be improved when the same plasma processing is performed in each set of plasma processing spaces. In addition, when different plasma processing is performed in each set of plasma processing spaces, continuous processing by a flat flow method is possible.

1 is a side sectional view showing a configuration of a first embodiment of a plasma processing apparatus of the present invention. It is an expanded sectional side view which shows the structure of the principal part of the plasma processing apparatus of the said 1st Embodiment. It is a sectional side view which shows the structure of the electrode part of the plasma processing apparatus of 1st Embodiment. It is a schematic cross section which shows another example of the opening control part which adjusts the flow volume and flow velocity of the gas of the plasma processing apparatus of 1st Embodiment. It is a wave form diagram which shows an example of the voltage waveform applied to the main electrode of the plasma processing apparatus of 1st Embodiment. It is a wave form diagram which shows another example of the voltage waveform applied to the main electrode of the plasma processing apparatus of 1st Embodiment. It is a wave form diagram which shows another example of the voltage waveform applied to the plasma processing apparatus of 1st Embodiment. It is a sectional side view which shows the structure of the plasma processing apparatus of the reference example of this invention. It is a wave form diagram which shows an example of the voltage waveform applied to the plasma processing apparatus of the said reference example . It is a sectional side view which shows the structure of the plasma processing apparatus of 2nd Embodiment of this invention. It is a sectional side view which shows the structure of the plasma processing apparatus of 3rd Embodiment of this invention. It is a perspective view of the plasma processing apparatus in the first embodiment. It is sectional drawing of the conventional plasma processing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chamber upper part 2 Chamber lower part 3 Upper electrode unit 4 Lower electrode unit 5 Main electrode 6 Side electrode 7 1st dielectric part 8 2nd dielectric part 9-1, 9-2 Gas reservoir 10 Refrigerant 11-1, 11 -2 Gas ejection port 12 Upper electrode cover 13 Roll for conveying object 14 Object to be treated 15 Plasma treatment space 16-1, 16-2 Predischarge area 17a, 17b Material inlet / outlet port 18, 33 High frequency power supply 19, 34 pulse Power supply 20 Gas reservoir (exhaust side)
21-1, 21-2 Gas supply port 22 Exhaust port 23 Roller shaft 24 Creeping discharge part 25 Chamber side member 26-1, 26-2 Gas flow path 27 Power transmission path (upper part, hot)
28 Electric circuit (upper part, ground)
29 Power transmission line (bottom, hot)
30 Electric circuit (bottom, ground)
31 Main electrode (bottom)
32 side electrode (lower part)
35-1, 35-2 Flow rate adjusting plate 36 High frequency voltage applied to the main electrode 5 37 High frequency voltage applied to the main electrode 31 38 Pulse voltage applied to the main electrode 5 39 Pulse voltage applied to the main electrode 31 40 DC applied to the main electrode 5 Pulse voltage 41 DC pulse voltage applied to the main electrode 31 42 High-frequency voltage applied to the main electrode 5 43-1 and 43-2 Flow adjustment cam

Claims (6)

A gas supply unit for supplying a predetermined processing gas to the plasma processing space in which the workpiece is disposed;
A first electrode facing the plasma processing space and generating an electric field in the plasma processing space;
An electric field is formed in the plasma processing space by facing the plasma processing space, facing the first electrode across the plasma processing space, and forming an electric field with the first electrode. A second electrode for converting the processing gas into plasma,
The processing gas is opposed to the side surface of the first electrode adjacent to the facing surface of the first electrode facing the plasma processing space with a predetermined gap and an electric field is formed in the predetermined gap. A third electrode for converting to plasma;
A first power supply unit for supplying first power to the first electrode,
The opposing surface and the side surface of the first electrode are connected by a convex curved surface ,
The facing surface of the first electrode is a flat surface facing the plasma processing space, and the second electrode has a flat surface facing the flat surface of the first electrode,
After the processing gas supplied by the gas supply unit passes through the gap between the side surface of the first electrode and the third electrode, the processing gas between the first electrode and the second electrode is used. A structure that passes through the plasma processing space,
Furthermore, the third electrode is grounded,
The plasma processing apparatus, wherein the first power supplied to the first electrode and the second power supplied to the second electrode have different phases or amplitudes . The plasma processing apparatus according to claim 1,
A first dielectric portion covering the opposing surface and the side surface of the first electrode;
A second dielectric portion covering the side surface of the third electrode facing the side surface of the first electrode,
The plasma processing apparatus, wherein the first dielectric part and the second dielectric part are opposed to each other with a predetermined gap. The plasma processing apparatus according to claim 1,
The third electrode is grounded;
A second power supply unit that supplies the second power to the second electrode;
The first power supplied from the first power supply unit to the first electrode and the second power supplied from the second power supply unit to the second electrode are at least in phase or amplitude. One is different,
The first power and the second power are:
A plasma processing apparatus, which is high-frequency power, pulse-wave power, power obtained by switching high-frequency power and pulse-wave power, or power obtained by superimposing high-frequency power and pulse-wave power. The plasma processing apparatus according to claim 1,
The gas supply unit
A gas jet for supplying the processing gas to the gap between the first electrode and the third electrode;
A plasma processing apparatus, comprising: an opening control unit that changes at least one of an opening area or an opening shape of the gas ejection port. The plasma processing apparatus according to claim 2, wherein
A dielectric coating formed on the opposing surface and the side surface of the first electrode;
The plasma processing apparatus, wherein the first dielectric portion covers the dielectric film. The plasma processing apparatus according to claim 5 , wherein
A plasma processing apparatus, wherein a gap between the first electrode and the first dielectric portion is 500 μm or less.

Images