JP2008204650A - Plasma treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treatment device to suppress temperature elevation of an electrode surface, suppress discharge of thermoelectrons, and prevent transition to an arc discharge. <P>SOLUTION: Since a voltage is applied between electrodes 2a, 2b from a high frequency power supply 1, plasma 5 is formed between a dielectric 4a and a dielectric 4b. A treated base material 6 is conveyed in a conveyance passage 9 which is formed by a barrier rib 8, has a cross sectional area necessary enough for conveyance, and has air tightness at least in the upper part direction, a gas supplying part 10a to supply a first process gas between the electrodes 2a, 2b is formed in the upstream of the conveyance passage 9, and a gas exhaust part 11a to exhaust the first process gas is installed in the downstream. Furthermore, in contact with the dielectric 4a, the gas supplying part 10b to supply a second process gas between the electrodes is installed at the upstream side of the conveyance passage 9 and the gas exhaust part 11b to exhaust a second process gas 12b is installed at the downstream side. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus, and more particularly 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 the like. The present invention relates to a plasma processing apparatus used in apparatuses for manufacturing flat panel displays such as EL (electroluminescence) panels and PDP (plasma display panels), solar cells and the like.

  In recent years, in the manufacturing process of semiconductors, flat panel displays, solar cells, etc., atmospheric pressure plasma technology that does not require large-scale equipment such as vacuum chambers and exhaust devices for substrates to be processed such as glass substrates and semiconductor wafers. Increasing attention is being paid to the processes such as modification, cleaning, processing, and film formation, which have been put into practical use in some processes such as surface modification, cleaning, and dry etching.

  However, when a long-time discharge is performed, the temperature of the electrode surface rises due to collision between particles in the plasma and the electrode or radiation heat, so that thermionic electrons are likely to be emitted. As a result, the spatial density of the thermoelectrons is increased, and the electrons are biased in the glow discharge space, so that the transition from the glow discharge to the arc discharge is facilitated. When it shifts to arc discharge, plasma becomes high temperature, and there arises a problem that the electrode itself melts in addition to thermal damage to the substrate to be treated.

For this reason, there has been known one that ensures the thermal stability of the electrode surface by constantly changing the electrode surface in contact with plasma by using a rotating electrode (see, for example, Patent Document 1).
Japanese Patent No. 30069271

  However, when a rotating electrode is used, a mechanism system and a power source for rotating the electrode portion are necessary, and the apparatus becomes large, and because of variations due to electrode vibration and eccentricity, spatially and processically. Need to take a lot of redundancy. In particular, when the plate-like substrate to be processed is transported in one direction, passed through the plasma space, and subjected to the plasma treatment, it is sufficiently foreseen that the variation in the processing amount will increase.

  The present invention relates to a pair of counter electrodes, at least one of which is coated with a dielectric material to generate plasma between electrodes, a carry-in path for carrying a substrate to be treated between the electrodes, and a substrate to be treated from between the electrodes The first process gas is supplied between the electrodes from the upstream of the carry-in path, the substrate transport member that carries the substrate to be treated between the electrodes through the carry-in path and the carry-out path, and the unloaded substrate. A first gas supply unit that discharges the first process gas from the downstream of the carry-out path, and a first gas supply unit that is closer to the counter electrode than the first gas supply unit and between the electrodes from the upstream of the carry-in path. (2) A plasma processing apparatus comprising: a second gas supply unit that supplies process gas; and a second gas exhaust unit that exhausts the second process gas from the downstream of the carry-out path closer to the counter electrode than the first gas exhaust unit. It is to provide.

According to the present invention, the first process gas is supplied to the surface of the substrate to be processed that directly contributes to the treatment, and the second process gas is supplied to the electrode surface so as to suppress the temperature rise of the electrode surface.
Therefore, the thermal stability of the electrode surface is effectively ensured.

  The plasma processing apparatus according to the present invention includes a pair of counter electrodes, at least one of which is coated with a dielectric to generate plasma between the electrodes, a loading path for loading a substrate to be processed between the electrodes, and between the electrodes A carry-out path for carrying out the substrate to be treated, a substrate conveying member carrying in and carrying out the substrate to be treated between the electrodes through the carry-in path and the carry-out path, and a first electrode between the upstream from the carry-in path. A first gas supply unit that supplies process gas, a first gas exhaust unit that exhausts the first process gas from the downstream of the carry-out path, and an upstream side of the carry-in path that is closer to the counter electrode than the first gas supply unit. A second gas supply unit configured to supply a second process gas between the electrodes; and a second gas exhaust unit configured to exhaust the second process gas from the downstream of the carry-out path closer to the counter electrode than the first gas exhaust unit. It is characterized by that.

The second gas supply unit and the second gas exhaust unit are disposed adjacent to or integrally with the counter electrode, and the second gas supply unit and the second gas exhaust unit are orthogonal to the moving direction of the substrate to be processed. A gas supply port and a gas discharge port that are slit-shaped in the direction and along the electrode surface may be provided.
It is preferable that the first process gas and the second process gas are substantially laminar between the electrodes, and the flow rate of the second process gas between the electrodes is faster than the flow rate of the first process gas.

The specific heat capacity of the second process gas may be larger than the specific heat capacity of the first process gas.
The second process gas may include helium and hydrogen.
The supply temperature of the second process gas may be lower than room temperature.
The second process gas may contain water.
As described above, the second gas supply unit and the second gas exhaust unit are disposed adjacent to or integrally with the counter electrode, and the second gas supply unit and the second gas exhaust unit are formed of the substrate to be processed. By providing a gas supply port and a gas discharge port that are slit-shaped in a direction perpendicular to the moving direction and that follow the electrode surface, the second process gas can easily flow on the electrode surface due to the Coanda effect. Therefore, it becomes easy for the first process gas and the second process gas to form a laminar flow in the plasma.

Furthermore, if the first process gas flow is not directly sprayed on the electrode surface, the influence on the second process gas flow can be reduced.
Further, by increasing the flow rate of the second process gas between the electrodes, that is, in the plasma processing space, a large amount of heat on the surface of the electrodes can be taken and the temperature rise can be suppressed.

In addition, the discharge state that has been ordered by increasing the flow rate of the process gas, that is, the discharge that becomes non-uniform treatment on the surface of the substrate to be processed, shifts to a uniform discharge that is not ordered. However, in order to increase the flow velocity in a certain discharge space, it is necessary to increase the supply amount of the process gas, which increases the consumption of the process gas, which is uneconomical. Only the flow rate of the process gas needs to be increased, and the consumption of the entire process gas can be suppressed.
Further, even when the second process gas is a gas having a large specific heat capacity, a large amount of heat on the electrode surface can be taken away, and an increase in temperature on the electrode surface can be suppressed.
The second process gas has a small influence that the gas itself contributes to the processing of the substrate to be processed. Therefore, if the second process gas contains helium or hydrogen having a large specific heat capacity more than the first process gas, the temperature of the electrode surface is further increased. Can be suppressed.
Alternatively, the temperature rise of the electrode surface can be suppressed by lowering the temperature of the second process gas itself.

  Alternatively, water is contained in the gas by a method such as bubbling before introducing the second process gas, so that the water in the second process gas is vaporized by the plasma in the vicinity of the electrode surface, and the surrounding heat is taken away. The increase in electrode temperature can be suppressed.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
Embodiment 1
FIG. 1 shows a first embodiment of a plasma processing apparatus according to the present invention. Cooling water 3 flows inside a metal electrode 2a to which the high frequency power source 1 is connected. The outside of the electrode 2a is covered with a dielectric 4a made of ceramic. The electrode 2b is installed at a position facing the electrode 2a. Like the electrode 2a, the cooling water 3 flows inside the electrode 2b, and the outside is covered with the dielectric 4b. When a voltage is applied between the high frequency power source 1 and the electrodes 2a and 2b, a plasma 5 is formed between the dielectric 4a and the dielectric 4b. The substrate 5 to be treated is transported to the plasma 5 in the direction indicated by the white arrow by the transport member 7 and subjected to a desired plasma treatment. The to-be-processed base material 6 is conveyed in the conveyance path 9 which is formed with the partition wall 8 and has a cross-sectional area necessary and sufficient for conveyance, and has airtightness in at least the upper direction, and is upstream of the conveyance path 9. A gas supply unit 10a for supplying the first process gas 12a between the electrodes 2a and 2b is installed, and a gas exhaust unit 11a for exhausting the first process gas 12a is installed downstream. Further, in contact with the dielectric 4a, a gas supply unit 10b that supplies the second process gas 12b between the electrodes on the upstream side of the transport path 9, and a gas exhaust unit 11b that exhausts the second process gas 12b on the downstream side. is set up. The second process gas can supply a gas having a larger specific heat capacity than the first process gas. Although not shown in the figure, the gas supply unit 10b supplies H ₂ , He, and N ₂ as gas supplies. From the unit 10a, H ₂ , He, O ₂ , N ₂ , Ar, and CF ₄ are selected and supplied according to the application. Since the second process gas itself has little influence on the treatment of the substrate to be treated, it is more preferable to supply it with a high ratio of helium or hydrogen having a large specific heat capacity. Note that the flow rates of the gases 12a and 12b are set so that they are almost laminar between the electrodes 2a and 3b, and the gas 12b has a faster laminar flow than the gas 12a.

  FIG. 2 is an enlarged view of an electrode portion in this plasma processing apparatus. As described above, the gas supply unit 10b and the gas exhaust unit 11b are arranged so as to sandwich the dielectric 4a. The gas 12b is supplied from the gas supply unit 10b so as to flow on the surface of the dielectric 4a, and the gas exhaust unit 11b. From this, the gas 12b is exhausted. The gas supply unit 10b and the gas exhaust unit 11b have a gas supply port and a gas discharge port that are slit-shaped in a direction orthogonal to the moving direction of the substrate 6 and along the surface of the dielectric 4a, respectively. Prepare.

Embodiment 2
In this embodiment, as shown in FIG. 3, the gas supply part 10b and a part of the gas exhaust part 11b are formed using the dielectric 4a. Other configurations conform to the first embodiment. Since the dielectric 4a is made of ceramic and can improve the smoothness of the surface, the gas 12b easily flows along the surface.

Embodiment 3
In this embodiment, as shown in FIG. 4, a part of the gas supply unit 10 b protrudes to the center side of the transport path 9. Other configurations conform to the first embodiment. For this reason, the gas 12a supplied from the gas supply unit 10a flows (deflects) toward the center of the transport path 9, and does not disturb the flow of the gas 12b.

Embodiment 4
In this embodiment, as shown in FIG. 5, the pure water 14 is passed through before the gas 12b is supplied to the gas supply unit 10b. Other configurations conform to the first embodiment. Thereby, moisture is contained in the gas 12b, and the surface of the dielectric 4a is easily cooled by the heat of vaporization of moisture in the gas 12b. Furthermore, by keeping the temperature of the pure water 14 at about 5 to 20 ° C. below room temperature, the temperature of the second process gas can be lowered below room temperature, and the temperature rise on the electrode surface can be suppressed. In the case of water repellency treatment using CF ₄ gas or the like, this method is not suitable because there is generation of HF due to the reaction of F in gas 12a and H in 12b, and O ₂ gas. It is applied to an ashing process using a material such as a hydrophilization process.

Embodiment 5
In this embodiment, as shown in FIG. 6, the gas supply part 10c and the gas exhaust part 11c are arrange | positioned so that the dielectric material 4b may be pinched | interposed, and another structure is based on Embodiment 1. FIG. As a result, the surface of the dielectric 4b is easily cooled. This suppresses uneven discharge on the dielectric 4b side.
In this case, since the transport member 7 is provided on the lower side of the substrate 6 to be processed, the dielectric 4b, the gas supply unit 10c, and the gas exhaust unit 11c are arranged in the gap of the transport member 7. Needs to be put together in a compact. Therefore, in such a case, it is preferable to form part of the gas supply units 10b and 10c and the gas exhaust units 11b and 11c as shown in the second embodiment by using the dielectrics 4a and 4b.

  According to the present invention, while suppressing the consumption of process gas and suppressing the temperature rise on the electrode surface, the discharge of thermionic electrons from the electrode surface is suppressed to maintain the glow discharge. It is possible to generate a plasma with good uniformity in which seeds exist, and to realize a plasma processing apparatus that can achieve both low running cost and high speed processing.

It is a sectional side view which shows the structure of Embodiment 1 of the plasma processing apparatus of this invention. It is an expanded side sectional view which shows the structure of the principal part of the plasma processing apparatus of Embodiment 1. It is an expanded sectional side view which shows the structure of the principal part of the plasma processing apparatus of Embodiment 2 of the plasma processing apparatus of this invention. It is an expanded sectional side view which shows the structure of the principal part of the plasma processing apparatus of Embodiment 3 of the plasma processing apparatus of this invention. It is an expanded sectional side view which shows the structure of the principal part of the plasma processing apparatus of Embodiment 4 of the plasma processing apparatus of this invention. It is a sectional side view which shows the structure of Embodiment 5 of the plasma processing apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High frequency power supply 2a, 2b Electrode 3 Cooling water 4a, 4b Dielectric 5 Plasma 6 Substrate to be processed 7 Conveyance member 8 Bulkhead 9 Conveyance path 10a, 10b, 10c Gas supply part 11a, 11b, 11c Gas exhaust part 12a, 12b Gas

Claims (8)

  A pair of counter electrodes, at least one of which is coated with a dielectric material to generate plasma between the electrodes, a carry-in path for carrying a substrate to be treated between the electrodes, and a carry-out carrying the substrate to be treated from between the electrodes A substrate, a substrate transport member that loads and unloads the substrate to be processed between the electrodes through the loading path and the unloading path, and a first gas that supplies a first process gas between the electrodes from upstream of the loading path A supply unit, a first gas exhaust unit for exhausting the first process gas from the downstream of the carry-out path, and a second process gas between the electrodes from the upstream of the carry-in path closer to the counter electrode than the first gas supply unit. A plasma processing apparatus comprising: a second gas supply unit for supplying; and a second gas exhaust unit for exhausting a second process gas from the downstream of the carry-out path closer to the counter electrode than the first gas exhaust unit.   The second gas supply unit and the second gas exhaust unit are disposed adjacent to or integrated with the counter electrode, and the second gas supply unit and the second gas exhaust unit are orthogonal to the moving direction of the substrate to be processed. The plasma processing apparatus according to claim 1, further comprising a gas supply port and a gas discharge port each having a slit shape and a shape extending along the electrode surface.   The plasma processing apparatus according to claim 2, wherein the carry-in path includes a protrusion that deflects the flow of the first process gas toward the center of the carry-in path upstream of the second gas supply unit.   The plasma processing apparatus according to claim 1, wherein the first process gas and the second process gas are substantially laminar between the electrodes, and the flow rate of the second process gas between the electrodes is faster than the flow rate of the first process gas.   The plasma processing apparatus of claim 1, wherein the specific heat capacity of the second process gas is larger than the specific heat capacity of the first process gas.   The plasma processing apparatus according to claim 5, wherein the second process gas contains helium and hydrogen.   The plasma processing apparatus according to claim 1, wherein the supply temperature of the second process gas is lower than room temperature.   The plasma processing apparatus according to claim 1, wherein the second process gas contains water.

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