JP2006351678A - Plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce uneven treatment by suppressing the drop of voltage in a lift pin mechanism 10. <P>SOLUTION: The plasma processing apparatus S is provided with an electrode stage 2 to suck and hold a substrate 4 to be processed by a suction surface 6, a lift pin mechanism 10 to release the substrate 4 to be processed from the suction surface 6 by allowing a pin 12 to be projected from the suction surface 6, and a counterelectrode 3 enabling electric discharging between the electrode stage 2 and itself. The apparatus generates a plasma between the counterelectrode 3 and the electrode stage 2 in an atmosphere. The lift pin mechanism 10 is provided with a gap 13 that is formed between the pin 12 and the substrate 4 sucked to the suction surface 6 while pin 12 is being embedded in the electrode stage 2 and a voltage drop prevention means 20 to suppress the drop of voltage in the gap 13 during plasma processing of the substrate 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus, and more particularly to an apparatus that performs plasma processing in a pressure environment near atmospheric pressure.

  For example, it is widely known that surface treatment is performed on a substrate such as glass or plastic by low-pressure glow discharge plasma of about 0.1 to 10 Torr, and it is also applied industrially. When the processing environment is set to such a low pressure of a vacuum level, the transition from discharge to arc discharge can be prevented, so that surface treatment can be performed even if the substrate is a plastic having low heat resistance.

  However, when performing surface treatment with low-pressure glow discharge plasma, an expensive vacuum chamber or vacuum exhaust device is required as a processing container. In addition, there is a field in which the size of a substrate is being increased as represented by an increase in the screen size of a so-called liquid crystal television or the like. In this case, a larger vacuum chamber or a vacuum exhaust device is required. As a result, it is inevitable that the device cost increases and the footprint of the device increases. In addition, when a surface treatment is performed on a substrate having a high water absorption rate, it takes a long time to evacuate the inside of the vacuum chamber, resulting in a problem that the processing cost itself is increased.

  Therefore, in order to overcome the above-mentioned various problems, an apparatus has been proposed in which glow discharge plasma is generated under atmospheric pressure to perform substrate surface treatment (see, for example, Patent Document 1).

  As shown in FIG. 8, such a plasma processing apparatus includes an electrode stage 103 that holds a substrate 107 to be processed, and a counter electrode 102 that is disposed to face the electrode stage 103. A plurality of gas supply holes (not shown) through which the processing gas flows are formed in the counter electrode 102, and a power source 101 for applying a voltage is connected. On the other hand, the electrode stage 103 includes a lift pin mechanism 105 that pushes up and supports the substrate 107 to be processed and an adsorption groove 104 that adsorbs the substrate 107 to be processed to the surface of the electrode stage 103 and is grounded.

  The suction groove 104 has a gap portion 108 between the substrate 107 to be processed and the electrode stage 103, but plasma is easily generated in the gap portion 108 because the inside has a low pressure. Therefore, the voltage drop in the suction groove 104 is relatively small.

As shown in FIG. 9, which is an equivalent circuit, a circuit configuration in which a resistor 111, a capacitor 112, and a resistor 113 are connected in series between the power supply 101 and the ground unit 115 in the vicinity of the suction groove 104 is considered. be able to. The resistor 111 indicates a voltage drop between the counter electrode 102 and the substrate 107 to be processed. The capacitor 112 is an electric capacity in the substrate 107 to be processed. The resistor 113 indicates a voltage drop in the suction groove 104. Although the voltage drop in the capacitor 112 is relatively large, the voltage drop in the resistors 111 and 113 is relatively small. As described above, since the voltage drop in the gap 108 of the suction groove 104 is small, the processing unevenness on the substrate 107 to be processed does not substantially occur.
Japanese Patent Laid-Open No. 7-118857

  Incidentally, as shown in FIG. 8, since the mechanical accuracy of the lift pin mechanism 105 is limited, not only a gap is generated between the lift pin mechanism 105 and the electrode stage 103, but the lift pin mechanism 105 and the substrate 107 to be processed A gap 109 is also formed between them. However, since the pressure in the gap 109 is atmospheric pressure, no plasma is generated even when a voltage is applied. As a result, the voltage drop in the gap 109 becomes large.

  That is, as shown in FIG. 10, which is an equivalent circuit, in the vicinity of the lift pin mechanism 105, a circuit configuration in which a resistor 111, a capacitor 112, and a capacitor 114 are connected in series between a power source 101 and a grounding portion 115. Can think. The capacitor 114 has an electric capacity in the gap portion 109 of the lift pin mechanism 105. Thus, since no plasma is generated in the gap 109 of the lift pin mechanism 105, it is inevitable that the voltage drop becomes relatively large. As a result, processing unevenness or so-called processing omission occurs on the substrate 107 to be processed.

  The present invention has been made in view of such various points, and an object thereof is to reduce processing unevenness in a gap portion of a lift pin mechanism.

  In order to achieve the above object, in the present invention, a voltage drop suppressing means for suppressing a voltage drop in the gap portion of the lift pin mechanism during plasma processing is provided.

  Specifically, a plasma processing apparatus according to the present invention includes an electrode stage that holds a substrate to be processed by suction and holds a pin, and a pin that is provided on the electrode stage and that can be projected and retracted from the suction surface of the electrode stage. A lift pin mechanism that separates the substrate to be processed from the suction surface by a pin protruding; and a counter electrode that is disposed opposite to the electrode stage and is capable of discharging between the electrode stage and having an atmospheric pressure. A plasma processing apparatus that plasma-processes the substrate to be processed by generating plasma between the electrode stage and the counter electrode in an atmosphere, wherein the lift pin mechanism is configured so that the pin and the pin are immersed in the electrode stage. A gap formed between the substrate to be processed adsorbed on the adsorption surface and the gap during plasma processing of the substrate to be processed And a suppressing voltage drop suppression means the voltage drop across.

  The voltage drop suppressing means is preferably plasma generating means for generating plasma in the gap during plasma processing of the substrate to be processed.

  The plasma generating means may have a sealing structure that seals the gap in a low pressure state.

  The sealing structure includes a cylinder portion that is opened in the suction surface of the electrode stage and provided with the pin, and is fitted into the pin, and a part of the cylinder portion including the gap portion is processed. It is preferable to have a sealing member for sealing with the substrate.

-Action-
Next, the operation of the present invention will be described.

  The substrate to be processed is sucked and held on the suction surface of the electrode stage in a state where the pins of the lift pin mechanism are immersed in the electrode stage. By performing discharge between the electrode stage and the counter electrode, plasma is generated between the electrode stage and the counter electrode in an atmosphere of atmospheric pressure. As a result, the substrate to be processed is subjected to plasma processing. The plasma-treated substrate is detached from the electrode stage when the pins of the lift pin mechanism protrude from the suction surface of the electrode stage.

  In the lift pin mechanism, a gap is formed between the substrate to be processed and the pin in a state where the substrate to be processed is sucked and held on the electrode stage. Since the voltage drop suppression means is provided in the gap, the voltage drop in the gap is suppressed during the plasma processing of the substrate to be processed. As a result, the local voltage drop in the substrate to be processed is suppressed, so that the processing unevenness of the plasma processing on the substrate to be processed is reduced.

  The voltage drop suppression means can be constituted by plasma generation means. The plasma generating means generates plasma in the gap during plasma processing of the substrate to be processed. That is, since plasma is generated between the substrate to be processed and the pins, the voltage drop in the gap is suppressed.

  Furthermore, the plasma generating means can be configured by a sealing structure that seals the gap in a low pressure state. If the gap is in a low pressure state, plasma is also generated in the gap due to the voltage applied between the electrode stage and the counter electrode during plasma processing of the substrate to be processed. As a result, the voltage drop in the gap is suppressed and processing unevenness is reduced.

  According to the present invention, since the voltage suppressing means for suppressing the voltage drop in the gap portion of the lift pin mechanism during the plasma processing is provided, plasma can be generated uniformly between the counter electrode and the electrode stage. As a result, the processing unevenness of the plasma processing can be reduced with respect to the substrate to be processed that is subjected to the plasma processing in an atmospheric pressure atmosphere.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment.

Embodiment 1 of the Invention
1 to 5 show Embodiment 1 of the present invention. As shown in FIG. 1 which is a cross-sectional view, the plasma processing apparatus S of the present embodiment includes an electrode stage 2 accommodated in the processing container 1 and a counter electrode 3. The substrate 4 to be processed such as a glass substrate held on the electrode stage 2 is subjected to plasma processing in an atmospheric pressure atmosphere.

  An exhaust pipe 5 for exhausting exhaust gas inside the processing container 1 is connected to the bottom of the processing container 1. One end of the exhaust pipe 5 is open to the atmosphere.

  The electrode stage 2 is composed of a plate-like conductive member, and has a suction surface 6 that sucks and holds the substrate 4 to be processed. As shown in FIG. 2 which is a plan view, a plurality of suction grooves 7 as suction portions are formed in a rectangular ring shape on the suction surface 6 in a plan view and are arranged concentrically. Each adsorption groove 7 is formed in a groove having a rectangular cross section, and as shown in FIG. 3, which is a cross-sectional view taken along the line III-III in FIG. 1, via an exhaust passage 8 formed at the bottom of the adsorption groove 7. They are connected by a vacuum pump (not shown) as decompression means. Then, by driving the vacuum pump while the substrate 4 to be processed is placed on the suction surface 6, a vacuum force is generated inside the suction groove 7 to suck and hold the substrate 4 to be processed. ing. The electrode stage 2 is electrically grounded.

  The electrode stage 2 is provided with a lift pin mechanism 10 for detaching the substrate 4 to be processed from the suction surface 6. The lift pin mechanism 10 includes a cylinder part 11 formed on the electrode stage 2 and a pin 12 provided on the cylinder part 11.

  As shown in FIG. 4 which is an enlarged cross-sectional view, the cylinder portion 11 is configured by, for example, a cylindrical hole portion opened in the suction surface 6 of the electrode stage 2. The inner wall surface of the cylinder portion 11 is formed in a stepped shape in which the inner diameter of the electrode stage 2 on the suction surface 6 side (upper side in FIG. 4) is larger than the rear side of the electrode stage 2 (lower side in FIG. 4). That is, the cylinder part 11 is comprised by the 1st part 11a with a comparatively large internal diameter by the side of adsorption | suction surface 6, and the 2nd part 11b with a comparatively small internal diameter by the back side.

  The pin 12 is formed in a columnar shape and is configured to be movable in the length direction (that is, the vertical direction) of the cylinder portion 11. The upper end of the pin 12 is disposed below the suction surface 6 in a state where the pin 12 is moved to the lower storage position. In other words, the lift pin mechanism 10 has a gap portion 13 formed between the pin 12 and the substrate 4 to be processed adsorbed on the adsorption surface 6 with the pin 12 immersed in the electrode stage 2. On the other hand, the upper end of the pin 12 is disposed so as to protrude above the suction surface 6 in a state where the pin 12 has moved to the upper protruding position. That is, the pin 12 is configured to be able to protrude and retract from the suction surface 6 of the electrode stage 2.

  In this way, the pin 12 protrudes from the suction surface 6 and moves to the protruding position, thereby pushing up the substrate 4 to be detached from the suction surface 6.

  The counter electrode 3 is made of a conductive member, and is disposed to face the electrode stage 2. The counter electrode 3 is installed at an upper position inside the processing container 1, and the inside is formed in a hollow plate shape. One end of a gas introduction pipe 14 for introducing a processing gas into the counter electrode 3 is connected to the upper portion of the counter electrode 3. The other end side of the gas introduction pipe 14 extends to the outside of the processing container 1. And the power supply part 15 is connected to the counter electrode 3 through the gas introduction pipe | tube. Thus, the counter electrode 3 can be discharged between the electrode stage 2.

  The counter electrode 3 has a counter surface 16 that faces the suction surface 6 of the electrode stage 2. As shown in FIG. 4, a plurality of gas introduction holes 17 are formed in the opposing surface 16, and the processing gas supplied from the gas introduction pipe 14 to the inside of the opposing electrode 3 is processed through each gas introduction hole 17. It supplies to the board | substrate 4 side.

  In this way, the plasma processing apparatus S is, for example, 1 to several tens kV between the counter electrode 3 and the electrode stage 2 from the power supply unit 15 in a state where the processing gas is supplied between the counter electrode 3 and the electrode stage 2. By applying a voltage, plasma is generated between the counter electrode 3 and the electrode stage 2. The substrate to be processed 4 is plasma-processed by this plasma.

For example, when etching a thin film (thin film having chemical, mechanical, optical, or electrical properties) formed on the substrate 4 to be processed, CF ₄ and He or Ar are used as processing gases. It is preferable to apply a mixed gas. Further, in the case of performing a treatment that imparts water repellency to the surface of the substrate 4 to be treated, it is possible to apply a fluorine-containing gas such as CF ₄ , C ₂ F ₆ , and SF ₆ as the treatment gas. is there. Further, when a thin film of a metal oxide film such as SiO ₂ , TiO ₂ or SnO ₂ is formed on the surface of the substrate to be processed 4 to impart hydrophilicity to the substrate to be processed 4, a metal hydride gas or halogenated gas is used. It is possible to apply a metal gas and a gas of a metal organic compound such as a metal alcoholate or water vapor.

  As a feature of the present invention, the lift pin mechanism 10 includes voltage drop suppression means 20 that suppresses a voltage drop in the gap portion 13 during plasma processing of the substrate 4 to be processed. The voltage drop suppression means 20 is configured to enable energization between the substrate to be processed 4 and the pin 12 when plasma is generated between the counter electrode 3 and the electrode stage 2, thereby enabling The voltage drop is suppressed.

  For example, the voltage drop suppression unit 20 can be a plasma generation unit 20 that generates plasma in the gap portion 13 during plasma processing of the substrate 4 to be processed. Preferably, the plasma generating means 20 is constituted by a sealing structure 20 that seals the gap 13 in a low pressure state.

  The sealing structure 20 includes the cylinder portion 11 and a seal member 21 that is provided by being inserted into the pin 12 and seals a part of the cylinder portion 11 including the gap portion 13 with the substrate 4 to be processed. is doing. As shown in FIG. 4, a seal member 21 such as an O-ring is fixedly provided at a step portion between the first portion 11 a and the second portion 11 b of the cylinder portion 11. By this seal member 21, the first portion 11a and the second portion 11b are separated in an airtight manner.

  Further, the inside of the first portion 11 a of the cylinder portion 11 communicates with the inside of the suction groove 7 through a communication path 23 formed in the electrode stage 2. As a result, when the inside of the suction groove 7 is depressurized by the vacuum pump while the substrate to be processed 4 is attracted to the suction surface 6, the inside of the first portion 11 a is also decompressed via the communication path 23. It has become.

-Plasma treatment method-
Next, a plasma processing method for the substrate 4 to be processed by the plasma processing apparatus S will be described.

  First, in the substrate suction step, the substrate 4 to be processed is placed on the suction surface 6 of the electrode stage 2 with the pins 12 of the lift pin mechanism 10 moved to the storage position. Subsequently, the vacuum pump is driven to decompress the inside of the suction groove 7. At this time, the inside of the first portion 11a of the cylinder part 11 is also depressurized to be in a vacuum state. In this way, the substrate 4 to be processed is sucked and held on the suction surface 6 by the vacuum force generated in the suction groove 7 and the first portion 11a (gap portion 13).

  Next, in the plasma generation step, a processing gas is introduced into the counter electrode 3, and the processing gas is uniformly introduced into the space between the counter electrode 3 and the electrode stage 2 from each gas introduction hole 17 of the counter electrode 3. To supply. In this state, a predetermined voltage is applied from the power supply unit 15 to the counter electrode 3 to generate plasma between the counter electrode 3 and the substrate to be processed 4 on the electrode stage 2 in an atmosphere of atmospheric pressure. A plasma treatment such as etching is performed on the substrate 4 by this plasma. The exhaust gas inside the processing container 1 is naturally exhausted to the outside through the exhaust pipe 5.

  Next, in the substrate removal step, the substrate 4 to be processed that has been subjected to the plasma treatment is detached from the suction surface 6. That is, the driving of the vacuum pump is stopped and the supply of the processing gas is stopped. Subsequently, each pin 12 of the lift pin mechanism 10 is lifted from the storage position and moved to the protruding position. As a result, the substrate 4 to be processed is detached from the suction surface 6 of the electrode stage 2 and carried out.

  The plasma processing of the substrate 4 to be processed by the plasma processing apparatus S is performed through the above series of steps.

-Effect of Embodiment 1-
Therefore, according to the first embodiment, plasma processing can be performed in an atmosphere of atmospheric pressure, so that an expensive vacuum vessel is not required, and the apparatus cost can be reduced. In addition, since the lift pin mechanism 10 is provided with the sealing structure 20 that seals the gap portion 13 of the cylinder portion 11, the gap portion 13 (that is, between the substrate 4 to be processed and the pin 12). It is possible to generate plasma. As a result, the substrate 4 and the pin 12 can be energized by plasma, so that a voltage drop in the gap 13 can be suppressed.

  FIG. 5 shows an equivalent circuit of the plasma processing apparatus S. Since plasma is generated between the counter electrode 3 and the substrate 4 to be processed, it can be considered that a resistor 31 is provided. Further, it can be considered that the substrate 32 is provided with the capacitor 32. It can be considered that a resistor 33 is provided in the gap 13 because plasma is generated. That is, the gap portion 13 can be configured to correspond to the resistor 33 having a small voltage drop, not a capacitor having a large voltage drop.

  Thus, in this embodiment, since the local voltage drop in the space | gap part 13 can be suppressed, a plasma can be generated in the uniform state between the counter electrode 3 and the electrode stage 2. FIG. As a result, since uniform plasma processing can be performed over the entire surface of the substrate to be processed 4, it is possible to reduce plasma processing unevenness and so-called processing loss in an atmosphere of atmospheric pressure.

  In recent years, as represented by a liquid crystal display device, there is a field in which the substrate to be processed 4 is increased in size. However, according to the plasma processing apparatus S of this embodiment, the substrate to be processed 4 is increased in size. However, it is possible to reduce processing unevenness while suppressing an increase in the footprint of the apparatus.

<< Embodiment 2 of the Invention >>
6 to 7 show Embodiment 2 of the present invention. In the following embodiments, the same portions as those in FIGS. 1 to 5 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the present embodiment, the suction portion of the electrode stage 2 is configured by a plurality of suction ports 27 instead of the suction grooves 7. The suction ports 27 are equally arranged on the suction surface 6 of the electrode stage 2 in the form of a matrix, and are formed by vertical holes having a circular cross section that opens to the suction surface 6. The electrode stage 2 has a plurality of chamber portions 28 formed on the back side. Each chamber part 28 is connected to a vacuum pump (not shown) while communicating with a plurality of suction ports 27. Thus, by driving the vacuum pump, the inside of each chamber 28 is decompressed, and a vacuum force is generated at each suction port 27. Further, the lift pin mechanism 10 similar to that of the first embodiment is disposed between the suction ports 27.

  Even if the electrode stage 2 has such a configuration, the same effects as those of the first embodiment can be obtained. In addition, it is preferable in that the substrate to be processed 4 can be uniformly adsorbed and held throughout.

<< Other Embodiments >>
Although the sealing structure 20 has been described as an example of the voltage drop suppressing unit 20, the present invention is not limited to this, and other configurations in which a current is applied between the substrate 4 to be processed and the pins 12 may be employed.

  In addition to supplying the processing gas from the inside of the counter electrode 3, a supply pipe for supplying the processing gas to the side of the space between the counter electrode 3 and the electrode stage 2 is provided separately. You may do it. Even if the processing gas is supplied in this manner, it is possible to appropriately generate plasma between the counter electrode 3 and the electrode stage 2.

  As described above, the present invention is useful for a plasma processing apparatus that performs plasma processing under a pressure environment near atmospheric pressure, and particularly, when voltage drop in a lift pin mechanism is suppressed to reduce processing unevenness. Is suitable.

It is sectional drawing which shows schematic structure of the plasma processing apparatus of Embodiment 1. FIG. It is a top view which shows the external appearance of an electrode stage. It is the III-III sectional view taken on the line in FIG. It is the IV-IV sectional view taken on the line in FIG. It is a circuit diagram which shows the equivalent circuit of a plasma processing apparatus. 5 is a plan view showing an electrode stage 2 of Embodiment 2. FIG. It is the VI-VI sectional view taken on the line in FIG. It is sectional drawing which expands and shows the conventional plasma processing apparatus. It is a circuit diagram which shows the equivalent circuit in the conventional adsorption | suction groove | channel. It is a circuit diagram which shows the equivalent circuit in the conventional space | gap part.

Explanation of symbols

DESCRIPTION OF SYMBOLS S Plasma processing apparatus 2 Electrode stage 3 Counter electrode 4 Substrate 6 Substrate 6 Suction surface 10 Lift pin mechanism 11 Cylinder part 11a 1st part 11b 2nd part 12 Pin 13 Air gap part 20 Voltage drop suppression means (plasma generation means, sealing structure)
21 Seal member

Claims (4)

An electrode stage that holds and holds the substrate to be processed on the suction surface;
A lift pin mechanism that is provided on the electrode stage and has a pin that can be projected and retracted from the suction surface of the electrode stage, and causes the substrate to be detached from the suction surface when the pin protrudes;
A counter electrode disposed opposite to the electrode stage and capable of discharging between the electrode stage and generating a plasma between the electrode stage and the counter electrode in an atmosphere of atmospheric pressure; A plasma processing apparatus for plasma processing,
The lift pin mechanism includes a gap formed between the pin and the substrate to be processed adsorbed on the adsorption surface in a state where the pin is immersed in the electrode stage, and the gap when the substrate to be processed is subjected to plasma processing. And a voltage drop suppressing means for suppressing a voltage drop in the section. In claim 1,
The plasma processing apparatus, wherein the voltage drop suppressing means is a plasma generating means for generating plasma in the gap during plasma processing of the substrate to be processed. In claim 2,
The plasma processing apparatus, wherein the plasma generating means has a sealing structure that seals the gap in a low pressure state. In claim 3,
The sealing structure includes a cylinder portion that is opened in the suction surface of the electrode stage and provided with the pin, and is fitted into the pin, and a part of the cylinder portion including the gap portion is processed. A plasma processing apparatus, comprising: a sealing member that seals between the substrate and the substrate.

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