JP2013093265A - Plasma processing apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing apparatus and a method capable of entirely processing a desired area to be processed of a base material in a short period of time when uniformly performing high temperature heat treatment on a base material adjacent to the surface thereof for an extremely short period of time, or when performing low temperature plasma processing on a base material by irradiating plasma of a reaction gas or by simultaneously irradiating a base material with plasma and a reaction gas flow.SOLUTION: An inductively coupled plasma torch unit T includes: a spiral coil 3 disposed within a coolant flow path enclosed by a first quartz plate 4, a second quartz plate 5 and a coolant case 16; and a plasma injection port 8 formed in the bottom. The second quartz plate 5 and the coolant case 16 are secured by bolts 19 each screwed into a tap 18 respectively. While supplying a gas into a space 7 inside a long chamber enclosed by the second quartz plate 5 and a third quartz plate 6, a high-frequency power is supplied to the spiral coil 3 to generate a plasma in the space 7 inside the long chamber to thereby irradiate a base material 2 with the plasma.

Description

  The present invention includes a thermal plasma process for treating a substrate by irradiating the substrate with thermal plasma, a low-temperature plasma process for treating a substrate by simultaneously irradiating the substrate with plasma by a reactive gas or plasma and a reactive gas flow The present invention relates to a plasma processing apparatus and method.

  Conventionally, semiconductor thin films such as polycrystalline silicon (poly-Si) are widely used for thin film transistors (TFTs) and solar cells. In particular, the poly-Si TFT has a high carrier mobility and can be manufactured on a transparent insulating substrate such as a glass substrate. For example, a pixel circuit such as a liquid crystal display device, a liquid crystal projector, or an organic EL display device can be used. It is widely used as a switching element constituting the circuit or as a circuit element of a liquid crystal driving driver.

  As a method for manufacturing a high-performance TFT on a glass substrate, there is a manufacturing method generally called “high temperature process”. Among TFT manufacturing processes, a process using a high temperature with a maximum temperature of about 1000 ° C. is generally called a “high temperature process”. Features of the high-temperature process are that a relatively good quality polycrystalline silicon can be formed by solid phase growth of silicon, a good quality gate insulating layer can be obtained by thermal oxidation of silicon, and a clean polycrystalline. This is the point that an interface between silicon and the gate insulating layer can be formed. Due to these characteristics, a high-performance TFT having high mobility and high reliability can be stably manufactured in a high-temperature process.

  On the other hand, since the high temperature process is a process of crystallizing a silicon film by solid phase growth, a long-time heat treatment of about 48 hours is required at a temperature of about 600 ° C. This is a very long process, and in order to increase the process throughput, a large number of heat treatment furnaces are inevitably required, and it is difficult to reduce the cost. In addition, quartz glass has to be used as an insulating substrate with high heat resistance, so the cost of the substrate is high and it is said that it is not suitable for large area.

  On the other hand, a technique for lowering the maximum temperature in the process and manufacturing a poly-Si TFT on an inexpensive large-area glass substrate is a technique called “low temperature process”. Among TFT manufacturing processes, a process for manufacturing poly-Si TFTs on a heat-resistant glass substrate that is relatively inexpensive in a temperature environment where the maximum temperature is approximately 600 ° C. or lower is generally called a “low-temperature process”. In a low temperature process, a laser crystallization technique for crystallizing a silicon film using a pulse laser having an extremely short oscillation time is widely used. Laser crystallization is a technique that utilizes the property of crystallizing in the process of solidifying instantaneously by irradiating a silicon thin film on a substrate with high-power pulsed laser light.

  However, this laser crystallization technique has some major problems. One is a large amount of trap levels localized inside the polysilicon film formed by the laser crystallization technique. Due to the presence of the trap level, carriers that are supposed to move in the active layer by the application of voltage are trapped and cannot contribute to electrical conduction, which has adverse effects such as a decrease in TFT mobility and an increase in threshold voltage. Further, there is a problem that the size of the glass substrate is limited due to the limitation of the laser output. In order to improve the throughput of the laser crystallization process, it is necessary to increase the area that can be crystallized at one time. However, since the current laser output is limited, when this crystallization technique is adopted for a large substrate such as the seventh generation (1800 mm × 2100 mm), it takes a long time to crystallize one substrate.

  Laser crystallization technology generally uses a laser shaped in a line, and crystallization is performed by scanning this laser. This line beam is shorter than the width of the substrate because of limited laser output, and it is necessary to scan the laser several times in order to crystallize the entire surface of the substrate. As a result, a line beam seam area is generated in the substrate, and an area that is scanned twice is formed. This region is significantly different in crystallinity from the region crystallized by one scan. For this reason, the element characteristics of the two are greatly different, which causes a large variation in devices. Finally, since the laser crystallization apparatus has a complicated apparatus configuration and a high cost of consumable parts, there are problems that the apparatus cost and running cost are high. As a result, a TFT using a polysilicon film crystallized by a laser crystallization apparatus becomes an element with a high manufacturing cost.

  In order to overcome the problems such as the limitation of the substrate size and the high apparatus cost, a crystallization technique called “thermal plasma jet crystallization method” has been studied (for example, see Non-Patent Document 1). The technology is briefly described below. When a tungsten (W) cathode and a water-cooled copper (Cu) anode are opposed to each other and a DC voltage is applied, an arc discharge occurs between the two electrodes. By flowing argon gas between these electrodes under atmospheric pressure, thermal plasma is ejected from the ejection holes vacated in the copper anode. Thermal plasma is thermal equilibrium plasma, which is an ultra-high temperature heat source having substantially the same temperature of ions, electrons, neutral atoms, etc., and the temperature of which is about 10,000K. Therefore, the thermal plasma can easily heat the object to be heated to a high temperature, and the substrate on which the a-Si film is deposited scans the front surface of the ultra-high temperature thermal plasma at a high speed, thereby crystallizing the a-Si film. Can be

  Thus, since the apparatus configuration is very simple and the crystallization process is performed under atmospheric pressure, it is not necessary to cover the apparatus with an expensive member such as a sealed chamber, and the apparatus cost can be expected to be extremely low. The utilities required for crystallization are argon gas, electric power, and cooling water, which is a crystallization technique with low running costs.

  FIG. 6 is a schematic diagram for explaining a semiconductor film crystallization method using this thermal plasma.

  In FIG. 1, a thermal plasma generator 31 includes a cathode 32 and an anode 33 that is disposed to face the cathode 32 with a predetermined distance therebetween. The cathode 32 is made of a conductor such as tungsten. The anode 33 is made of a conductor such as copper, for example. Further, the anode 33 is formed in a hollow shape, and is configured to be cooled through water through the hollow portion. The anode 33 is provided with an ejection hole (nozzle) 34. When a direct current (DC) voltage is applied between the cathode 32 and the anode 33, an arc discharge is generated between the two electrodes. In this state, by flowing a gas such as argon gas between the cathode 32 and the anode 33 under atmospheric pressure, the thermal plasma 35 can be ejected from the ejection hole 34. Here, the “thermal plasma” is a thermal equilibrium plasma, which is an ultra-high temperature heat source having substantially the same temperature of ions, electrons, neutral atoms, etc., and having a temperature of about 10,000K.

  Such thermal plasma can be used for heat treatment for crystallization of a semiconductor film. Specifically, a semiconductor film 37 (for example, an amorphous silicon film) is formed on the substrate 36, and thermal plasma (thermal plasma jet) 35 is applied to the semiconductor film 37. At this time, the thermal plasma 35 is applied to the semiconductor film 37 while relatively moving along a first axis (left and right direction in the illustrated example) parallel to the surface of the semiconductor film 37. That is, the thermal plasma 35 is applied to the semiconductor film 37 while scanning in the first axis direction. Here, “relatively move” refers to relatively moving the semiconductor film 37 (and the substrate 36 supporting the semiconductor film 37) and the thermal plasma 35, and moving only one or both of them. Any of the cases are included. By such scanning of the thermal plasma 35, the semiconductor film 37 is heated by the high temperature of the thermal plasma 35 to obtain a crystallized semiconductor film 38 (polysilicon film in this example) (for example, see Patent Document 1). ).

  FIG. 7 is a conceptual diagram showing the relationship between the depth from the outermost surface and the temperature. As shown in the figure, by moving the thermal plasma 35 at a high speed, only the vicinity of the surface can be processed at a high temperature. After the thermal plasma 35 passes, the heated region is quickly cooled, so that the vicinity of the surface becomes high temperature for a very short time.

  Such a thermal plasma is generally generated in a dotted region. The thermal plasma is maintained by thermionic emission from the cathode 32, and thermionic emission becomes more active at a position where the plasma density is high. Therefore, positive feedback is applied, and the plasma density becomes higher. That is, arc discharge is concentrated on one point of the cathode, and thermal plasma is generated in a dotted region.

  If you want to process a flat substrate uniformly, such as when crystallizing a semiconductor film, it is necessary to scan a dotted thermal plasma over the entire substrate. In order to construct a process that can be processed, it is effective to widen the thermal plasma irradiation area. For this reason, techniques for generating thermal plasma over a large area have been studied for a long time.

  For example, a method for widening a plasma jet by simultaneously jetting a widening gas for widening the plasma jet from two locations in a direction intersecting the central axis of the outer nozzle onto a plasma jet ejected from the outer nozzle of the plasma torch Is disclosed (for example, see Patent Document 2). Alternatively, a plasma nozzle characterized in that the mouth portion of the nozzle passage is inclined at a predetermined angle with respect to the axis of the nozzle passage, and a casing constituting the nozzle passage, or a part of the casing, A method is disclosed in which a plasma nozzle is passed and moved along a workpiece by rotating it around the longitudinal axis at high speed (see, for example, Patent Document 3). Further, there is disclosed one provided with a rotating head having at least one eccentrically arranged plasma nozzle (see, for example, Patent Document 4).

  It is not intended to process a large area in a short time, but as a welding method using thermal plasma, a strip electrode is used and the width direction is arranged to be the weld line direction and welding is performed. A high-speed gas shielded arc welding method is disclosed (see, for example, Patent Document 5).

  In addition, an inductively coupled plasma torch having a linear elongated shape using a flat rectangular parallelepiped insulator material is disclosed (for example, see Patent Document 6).

  In addition, a method of generating a long and narrow linear plasma using a long electrode has been disclosed (for example, see Patent Document 7). Although described as generating heat plasma, it generates low-temperature plasma and is not suitable for heat treatment. If thermal plasma is generated, it is assumed that it is difficult to generate uniform thermal plasma in the longitudinal direction because arc discharge is concentrated in one place because of the capacitive coupling type using electrodes. On the other hand, the low temperature plasma processing apparatus is an apparatus capable of performing plasma processing such as etching and film formation by converting an etching gas or a gas for CVD (Chemical Vapor Deposition) into plasma.

  Further, a method for generating a long plasma using a microstrip line is disclosed (for example, see Patent Document 8). In this configuration, it is considered that the chamber wall surface in contact with the plasma cannot be completely cooled (not surrounded by the water-cooled flow path), and therefore cannot operate as a thermal plasma source.

  Moreover, what forms a linear elongate plasma torch by arranging a plurality of discharge electrodes in a line is disclosed (see, for example, Patent Document 9).

  An apparatus for performing etching or CVD that uses a planar spiral coil is disclosed (see, for example, Patent Document 10), which generates a large area plasma in a vacuum and forms a base material. Are related to a technical field different from the technical field of the present invention.

JP 2008-53634 A Japanese Patent Laid-Open No. 08-118027 JP 2001-68298 A Special Table 2002-500818 Japanese Patent Laid-Open No. 04-284974 Special table 2009-545165 gazette JP 2007-287454 A Special table 2010-539336 JP 2009-158251 A JP-A-3-79025

S. Higashi, H .; Kaku, T .; Okada, H .; Murakami and S.M. Miyazaki, Jpn. J. et al. Appl. Phys. 45, 5B (2006) pp. 4313-4320

  However, conventional techniques for generating a large area of thermal plasma have not been effective for applications in which the vicinity of the surface of a substrate is treated at a high temperature for a very short time, such as crystallization of a semiconductor.

  In the technology for generating thermal plasma in a large area described in Patent Document 2 shown in the conventional example, although the width is widened, the temperature distribution in the widened region is 100 ° C. or more and is uniform. Realization of heat treatment is impossible.

  Further, in the techniques described in Patent Documents 3 and 4 shown in the conventional example, the thermal plasma is generated in a large area, and the heat plasma is essentially oscillated. Since the time is shorter than when scanning without rotating, the time for processing a large area is not particularly shortened. Further, for uniform processing, it is necessary to make the rotation speed sufficiently higher than the scanning speed, and it is inevitable that the nozzle configuration becomes complicated.

  Moreover, the technique described in Patent Document 5 shown in the conventional example is a welding technique and is not a configuration for uniformly processing a large area. Even if this is applied to a large area processing application, in this configuration, since a point-like arc vibrates along the strip electrode, plasma is generated uniformly when time averaged, but instantaneously non-uniform plasma is generated. Has occurred. Therefore, it cannot be applied to large area uniform processing.

  Further, the technique described in Patent Document 6 shown in the conventional example is an inductively coupled high-frequency plasma torch, unlike the technique using DC arc discharge disclosed in Non-Patent Document 1 and Patent Document 1. It is a feature. Since it is an electrodeless discharge, it has the advantages of excellent thermal plasma stability (small time change) and less contamination (contamination) of electrode material into the substrate.

  In an inductively coupled plasma torch, in order to protect the insulator material from high-temperature plasma, a method is generally adopted in which the insulator material is made into a double tube configuration and a coolant is passed therebetween. However, in the technique described in Patent Document 6 shown in the conventional example, since the insulator material has a flat rectangular parallelepiped shape, a refrigerant having a sufficient flow rate can be obtained simply by adopting a double tube configuration. Can't flow. This is because the insulator material is generally inferior in mechanical strength to metal, and if the insulator material is too long in the longitudinal direction, the internal pressure of the double pipe cannot be increased. For this reason, there is a limit to uniformly processing a large area.

  Even in the case of dot-like thermal plasma, if the diameter is large, the number of scans during large area processing can be reduced, so that it can be processed in a short time depending on the application. However, if the diameter of the thermal plasma is large, the time for the thermal plasma to pass over the substrate during scanning becomes substantially longer, so that only the vicinity of the surface of the substrate cannot be treated at a high temperature for a very short time. Even a considerably deep region of the material becomes high temperature, which may cause defects such as cracking of the glass substrate and peeling of the film.

  Further, the technique described in Patent Document 9 shown in the conventional example is inferior in thermal plasma stability (large time change) as compared to the inductively coupled high-frequency plasma torch described above, and is based on the electrode material. There is a disadvantage that there is a lot of contamination (contamination) in the material.

  The present invention has been made in view of such a problem. When the high-temperature heat treatment is performed uniformly in the vicinity of the surface of the base material for a very short time, or the base material is irradiated with plasma by the reactive gas or plasma and the reactive gas flow at the same time. Therefore, it is an object of the present invention to provide a plasma processing apparatus and method capable of processing the entire desired region of the base material in a short time when the base material is subjected to low temperature plasma processing.

The plasma processing apparatus of the first invention of the present application has a long and linear opening, a long shape in a direction parallel to the longitudinal direction of the opening, and communicates with the opening. A long chamber surrounded by a dielectric member, a gas supply pipe for introducing gas into the chamber, a coil having a long shape in a direction parallel to the longitudinal direction of the opening, and the coil An apparatus including a connected high-frequency power source, a substrate mounting table, and a moving mechanism that can move the chamber and the substrate mounting table relatively in a direction perpendicular to the longitudinal direction of the opening. In
A space surrounded by the dielectric member and a cover disposed outside the dielectric member constitutes a refrigerant flow path, and the dielectric member and the cover are connected by a column. It is characterized by.

  With such a configuration, when the high temperature heat treatment is performed uniformly in the vicinity of the surface of the base material for a very short time, or the base material is subjected to low temperature plasma treatment by irradiating the base material with plasma or plasma and a reactive gas flow at the same time. In this case, the entire desired region to be treated of the substrate can be processed in a short time.

  In the plasma processing apparatus of the first invention of the present application, it is preferable that the coil preferably has one spiral shape as a whole.

  With such a configuration, a plasma processing apparatus can be realized with a simple configuration.

  In this case, it is preferable that the spiral coil is planar.

  With such a configuration, a plasma processing apparatus can be realized with a simpler configuration.

  Preferably, the inner wall surface of the chamber close to the spiral coil is a plane parallel to the plane formed by the spiral coil.

  With such a configuration, a plasma processing apparatus with high plasma generation efficiency can be realized.

  Preferably, the chamber is configured as a space sandwiched between two dielectric plates having at least one groove.

  With such a configuration, a plasma processing apparatus can be realized with a simple configuration.

  Preferably, the outer shape of the chamber is larger than the outer shape of the spiral coil.

  With such a configuration, a plasma processing apparatus with high plasma generation efficiency can be realized.

  Preferably, when defining “depth of the chamber” = “length of the chamber in the direction from the spiral coil to the chamber”, the depth of the chamber is 0.5 mm or more and 7 mm or less. It is desirable to be. More preferably, the depth of the chamber is 1 mm or more and 5 mm or less.

  With such a configuration, a plasma processing apparatus with high plasma generation efficiency can be realized.

  The opening may be provided on the opposite side of the spiral coil in the chamber, and the direction from the opening to the chamber and the direction from the spiral coil to the chamber are mutually different. It may be vertical.

  Alternatively, the coil may be disposed so as to surround the chamber, and may have a single solenoid shape as a whole.

  With such a configuration, a plasma processing apparatus can be realized with a simple configuration.

In the plasma processing method of the second invention of the present application, the gas is ejected from the slit-shaped opening formed in the chamber toward the substrate while supplying the gas into the long chamber surrounded by the dielectric member. A plasma processing method for generating a high-frequency electromagnetic field in the chamber by supplying high-frequency power to a coil having an elongated shape in a direction parallel to the longitudinal direction of the chamber,
While allowing the coolant to flow in a space surrounded by the dielectric member and the cover disposed outside the dielectric member, which are connected to each other by struts,
The surface of the base material is treated while relatively moving the chamber and the base material in a direction perpendicular to the longitudinal direction of the opening.

  With such a configuration, when the high temperature heat treatment is performed uniformly in the vicinity of the surface of the base material for a very short time, or the base material is subjected to low temperature plasma treatment by irradiating the base material with plasma or plasma and a reactive gas flow at the same time. In this case, the entire desired region to be treated of the substrate can be processed in a short time.

  According to the present invention, when a high temperature heat treatment is performed uniformly in the vicinity of the surface of the base material for a very short time, or the base material is subjected to low temperature plasma treatment by simultaneously irradiating the base material with plasma or plasma and a reactive gas flow. In this case, the entire desired region to be treated of the substrate can be processed in a short time.

Sectional drawing which shows the structure of the plasma processing apparatus in Embodiment 1 of this invention The perspective view which shows the structure of the plasma processing apparatus in Embodiment 1 of this invention. Sectional drawing which shows the structure of the plasma processing apparatus in Embodiment 2 of this invention. The perspective view which shows the structure of the plasma processing apparatus in Embodiment 2 of this invention. The perspective view which shows the structure of the plasma processing apparatus in Embodiment 3 of this invention. Sectional drawing which shows the structure of the plasma processing apparatus in a prior art example Conceptual diagram showing the relationship between the depth from the outermost surface and the temperature in the conventional example

  Hereinafter, a plasma processing apparatus according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIG. 1 and FIG.

  FIG. 1A shows the configuration of the plasma processing apparatus according to Embodiment 1 of the present invention, and is a cross-sectional view taken along a plane perpendicular to the longitudinal direction of an inductively coupled plasma torch unit. FIG. 1B is a cross-sectional view of the inductively coupled plasma torch unit cut along a plane parallel to the longitudinal direction and perpendicular to the substrate. 1B is a cross-sectional view taken along the broken line in FIG. 1A, and FIG. 1A is a cross-sectional view taken along the broken line in FIG.

  FIG. 2 is an assembly configuration diagram of the inductively coupled plasma torch unit shown in FIG. 1, in which perspective views of parts (parts) are arranged.

  1 and 2, the base material 2 is placed on the base material placing table 1. In the inductively coupled plasma torch unit T, a planar spiral coil 3 made of a conductor is disposed in the vicinity of the first quartz plate 4 and the second quartz plate 5. The long chamber made of dielectric is defined by a space (space 7 inside the long chamber) surrounded by the second quartz plate 5 and the third quartz plate 6. The inner wall surface of the long chamber near the spiral coil 3 is a plane parallel to the plane formed by the spiral coil 3. In such a configuration, since the distance from the spiral coil 3 to the long chamber is equal at any part of the spiral coil 3, inductively coupled plasma can be generated with small high-frequency power, and efficient plasma generation is possible. realizable.

  Further, the outer shape of the long chamber is configured to be larger than the outer shape of the spiral coil 3. Such a configuration also leads to an equal distance from the spiral coil 3 to the long chamber at an arbitrary portion of the spiral coil 3, so that a plasma processing apparatus with high plasma generation efficiency can be realized.

  The inductively coupled plasma torch unit T is entirely surrounded by a shield member (not shown) made of a grounded conductor, which can effectively prevent high-frequency leakage (noise) and effectively prevent undesirable abnormal discharge. Can be prevented.

  The space 7 inside the long chamber is surrounded by a flat surface forming one side of the second quartz plate 5 and a recess (groove) provided in the third quartz plate 6. That is, the entire long chamber is surrounded by a dielectric. The plasma generated in the space 7 inside the long chamber is ejected toward the base material 2 from the plasma ejection port 8 as a slit-like opening in the long chamber. Further, the longitudinal direction of the long chamber and the longitudinal direction of the plasma jet outlet 8 are arranged in parallel. Further, the plasma jet port 8 is provided on the opposite side to the spiral coil 3 in the long chamber.

  A plasma gas manifold 9 surrounded by a recess (groove) provided in the second quartz plate 5 and a flat surface (a surface facing the long chamber) forming one side of the first quartz plate 4 is provided. The gas supplied from the plasma gas supply pipe 10 to the plasma gas manifold 9 passes through a plasma gas supply hole 11 (through hole) as a long gas introduction portion provided in the second quartz plate 5, and the long chamber. It is introduced into the internal space 7. With such a configuration, a uniform gas flow in the longitudinal direction can be easily realized. The flow rate of the gas introduced into the plasma gas supply pipe 10 is controlled by providing a flow rate control device such as a mass flow controller upstream thereof.

  The plasma gas supply hole 11 is a long slit, but a plurality of round holes may be provided in the longitudinal direction.

  The central axis of the spiral coil 3 is arranged in parallel with the longitudinal direction of the long chamber and the longitudinal direction of the plasma jet port 8.

  Further, a straight line (dotted line A in FIG. 2) parallel to the longitudinal direction of the spiral coil 3 and passing through the center of the long chamber parallel to the longitudinal direction of the long chamber (dotted line in FIG. 2). B), a straight line parallel to the longitudinal direction of the plasma gas supply hole 11 and passing through the center of the plasma gas supply hole 11 (dotted line C in FIG. 2), and parallel to the longitudinal direction of the plasma outlet 8 and the center of the plasma outlet 8 The straight lines passing through (dotted line D in FIG. 2) are arranged in parallel and on the same plane. With such a configuration, the volume of the portion that generates plasma can be minimized while obtaining uniform plasma, so that a plasma processing apparatus with high plasma generation efficiency can be realized.

  Further, a shield gas nozzle 13 as a shield gas supply port is disposed in a portion close to the substrate mounting table 1, and a shield gas manifold 14 is provided therein. In this way, two systems of gas introduction are prepared, and a shielding gas is supplied in addition to the plasma gas suitable for plasma generation, such as oxygen and carbon dioxide in the atmosphere, which are unnecessary or have an adverse effect on the processing. It is possible to reduce contamination of the plasma irradiation surface. The shield gas supply port may be a slit having a shape that is long in a direction parallel to the long direction of the plasma outlet 8, or may be in a direction parallel to the long direction of the plasma outlet 8. It may be a number of holes arranged side by side.

  The spiral coil 3 is provided in the refrigerant flow path 15, and the refrigerant flow path 15 includes a space surrounded by the refrigerant case 16, the first quartz plate 4, and the second quartz plate 5. A space surrounded by the refrigerant case 17 and the third quartz plate 6 is also a refrigerant flow path 15. A plurality of taps 18 are joined to the surfaces of the second quartz plate 5 and the third quartz plate 6 forming the inner wall surface of the refrigerant flow path 15. The tap 18 is made of a dielectric and is selected from quartz, ceramics, resin, and the like. Joining can be performed by using various adhesives in addition to the welding method. Dielectric bolts 19 are screwed into the taps 18 through through holes provided in the refrigerant cases 16 and 17. An O-ring is provided between the head of the bolt 19 and the refrigerant cases 16 and 17. That is, the space surrounded by the second quartz plate 5 and the third quartz plate 6 as dielectric members and the refrigerant case 16 as a cover arranged outside these constitutes a refrigerant flow path, and The second quartz plate 5 and the third quartz plate 6 and the refrigerant case 16 are connected by a tap 18 and a bolt 19 as a support column.

  Two taps 20 are provided on the high-frequency power supply unit and the grounding unit of the spiral coil 3. The tap 20 is made of a conductor and is selected from copper, brass and the like. A conductor-made bolt 21 is screwed into the tap 20 through a through hole provided in the refrigerant case 16. An O-ring is provided between the head of the bolt 21 and the refrigerant case 16. A copper plate (not shown) or the like is sandwiched between the bolt 21 and the refrigerant case 16, and high-frequency wiring is made. A refrigerant, such as cooling water, is introduced into the refrigerant flow path 15 and discharged through the refrigerant pipe 23 provided in the refrigerant cases 16 and 17.

  Note that O-rings (not shown) are also provided on the contact surfaces of the refrigerant case 16 and the second quartz plate 5 and the refrigerant case 17 and the third quartz plate 6.

  As described above, the cooling water as the coolant flows around the spiral coil 3 and around the second quartz plate 5 and the third quartz plate 6 which are members constituting the long chamber. Cooling of the quartz plate 5 and the third quartz plate 6 is realized.

  Further, the structure in which the bolt 19 is screwed into the tap 18 allows the second quartz plate 5 and the third quartz plate 6 even when a large amount of refrigerant flows and the internal pressure (water pressure) in the refrigerant flow path 15 increases. The deformation of is difficult to occur. In other words, in the present embodiment, a much larger amount of refrigerant can be allowed to flow than in the case of water-cooling as a double-pipe structure in the technique described in Patent Document 6 shown in the conventional example, and effective cooling is achieved. Is possible. In order to further increase the rigidity, it is possible to devise the material and thickness of the refrigerant cases 16 and 17.

  A rectangular slit-shaped plasma ejection port 8 is provided, and the substrate mounting table 1 (or the substrate 2 on the substrate mounting table 1) is disposed to face the plasma ejection port 8. In this state, high-frequency power is supplied to the spiral coil 3 from a high-frequency power source (not shown) while gas is being jetted from the plasma nozzle 8 toward the substrate 2 while gas is being supplied into the long chamber. The thin film 22 on the substrate 2 can be plasma-treated by generating plasma in the space 7 inside the long chamber and irradiating the substrate 2 with the plasma from the plasma outlet 8. The base material 2 is processed by relatively moving the long chamber and the base material mounting table 1 in a direction perpendicular to the longitudinal direction of the plasma ejection port 8. That is, the inductively coupled plasma torch unit T or the substrate mounting table 1 is moved in the left-right direction in FIG. 1A and in the direction perpendicular to the paper surface in FIG.

  Various gases can be used as the gas supplied into the long chamber. However, considering the stability of the plasma, the ignitability, the life of the member exposed to the plasma, etc., it is desirable that the main gas is an inert gas. Among these, Ar gas is typically used. When plasma is generated only by Ar, the plasma becomes considerably high temperature (10,000 K or more).

  In this configuration, since the length in the longitudinal direction of the plasma outlet 8 is equal to or larger than the width of the base material 2, a single scan (the inductively coupled plasma torch unit T and the base material mounting table 1 is performed). The entire thin film 22 in the vicinity of the surface of the substrate 2 can be processed by relatively moving).

In such a plasma processing apparatus, a high-frequency power source (not shown) is supplied while Ar or Ar + H ₂ gas is supplied from a gas outlet into a long chamber and gas is jetted from the plasma outlet 8 toward the substrate 2. Further, by supplying high frequency power of 13.56 MHz to the spiral coil 3, plasma is generated by generating a high frequency electromagnetic field in the space 7 inside the long chamber, and the plasma is supplied from the plasma outlet 8 to the substrate 2. By performing irradiation and scanning, heat treatment such as crystallization of a semiconductor film can be performed.

As conditions for plasma generation, the distance between the plasma jet port 8 and the substrate 2 = 3 to 50 mm, the scanning speed = 50 to 3000 mm / s, the total plasma gas flow rate = 1 to 100 SLM, the H ₂ concentration in Ar + H ₂ gas = 0-10%, shielding gas (N ₂₎ flow rate = 1～100SLM, a value of about RF power = 0.5～10KW appropriate. However, among these quantities, the gas flow rate and power are values per 100 mm of the length of the plasma jet port 8. This is because it is considered appropriate to input parameters proportional to the length of the plasma jet port 8 for parameters such as gas flow rate and electric power.

  As described above, the long chamber and the substrate mounting table 1 are arranged in a direction perpendicular to the longitudinal direction of the plasma nozzle 8 while the longitudinal direction of the plasma nozzle 8 and the substrate mounting table 1 are arranged in parallel. Therefore, the length of the plasma to be generated and the processing length of the substrate 2 can be configured to be substantially equal. In addition, the width of the cross section obtained by cutting the long chamber along a plane perpendicular to the central axis (the width of the space 7 inside the long chamber in FIG. 1A) is the width of the plasma ejection port 8 (FIG. 1A It may be a little larger than the width of the gap). That is, the volume of plasma to be generated can be made extremely small compared to the conventional one. As a result, power efficiency is dramatically increased.

  If the “depth of the space 7 inside the long chamber” is defined as “the length of the long chamber in the direction from the spiral coil 3 to the long chamber”, the depth of the space 7 inside the long chamber is defined. This corresponds to d in FIG. When the experiment was conducted at atmospheric pressure with the length (length in the longitudinal direction) of the space 7 inside the long chamber being 95 mm and changing the depth d, when the depth d was 1 mm or more and 5 mm or less, the high frequency power was 10 kW. In the following, thermal plasma was successfully generated by Ar gas. If the high frequency power is further increased, it is considered that thermal plasma is generated even when the depth d is 0.5 mm or more and 7 mm or less, but if it is out of this range, inductively coupled plasma processing at atmospheric pressure is difficult.

  From this experimental result, it can be said that the depth d is preferably 0.5 mm or more and 7 mm or less, and more preferably, the depth d is 1 mm or more and 5 mm or less. This also indicates that the volume of the space 7 inside the long chamber may be small, and it is considered that high power efficiency can be obtained as compared with the conventional example.

(Embodiment 2)
The second embodiment of the present invention will be described below with reference to FIGS.

  FIG. 3A shows the configuration of the plasma processing apparatus according to the second embodiment of the present invention, and is a cross-sectional view taken along a plane perpendicular to the longitudinal direction of the inductively coupled plasma torch unit. FIG. 3B is a cross-sectional view taken along a plane parallel to the longitudinal direction of the inductively coupled plasma torch unit and perpendicular to the substrate. 3B is a cross-sectional view taken along the broken line in FIG. 3A, and FIG. 3A is a cross-sectional view taken along the broken line in FIG. FIG. 4 is an assembly configuration diagram of the inductively coupled plasma torch unit shown in FIG. 3, in which perspective views of parts (parts) are arranged.

  3 and 4, the base material 2 is placed on the base material placing table 1. In the inductively coupled plasma torch unit T, the dielectric long chamber has a quartz plate 25 provided below the lid 24, a cylindrical quartz tube 28, and a cylindrical one with a narrow opening. The space surrounded by the quartz nozzle 29 (space 7 inside the long chamber) is defined. The lower surface of the quartz tube 28 and the upper surface of the quartz nozzle 29 are joined in an annular shape without a gap. A helical solenoid coil 27 made of a conductor is disposed around the quartz tube 28 so as to surround the long chamber. The inner wall surface of the long chamber on the side close to the solenoid coil 27 forms a surface parallel to the cylindrical shape of the solenoid coil 27 as a whole. In such a configuration, since the distance from the solenoid coil 27 to the long chamber becomes equal at any part of the solenoid coil 27, inductively coupled plasma can be generated with a small high-frequency power, and efficient plasma generation can be achieved. realizable.

  The inductively coupled plasma torch unit T is entirely surrounded by a shield member (not shown) made of a grounded conductor, which can effectively prevent high-frequency leakage (noise) and effectively prevent undesirable abnormal discharge. Can be prevented.

  The space 7 inside the long chamber is surrounded by a quartz plate 25, a quartz tube 28, and a quartz nozzle 29. That is, the entire long chamber is surrounded by a dielectric. The plasma generated in the space 7 inside the long chamber is a base material from the plasma outlet 8 as a slit-like opening (a narrow opening provided below the quartz nozzle 29) in the long chamber. It spouts toward 2. Further, the longitudinal direction of the long chamber and the longitudinal direction of the plasma jet outlet 8 are arranged in parallel.

  A plasma gas manifold 9 is provided that is surrounded by a recess (groove) provided in the lid 24 and a flat surface (surface opposite to the long chamber) that forms one surface of the quartz plate 25. The gas supplied from the plasma gas supply pipe 10 to the plasma gas manifold 9 passes through a plasma gas supply hole 11 (through hole) as a long gas introduction portion provided in the quartz plate 25 and is provided inside the long chamber. It is introduced into the space 7. With such a configuration, a uniform gas flow in the longitudinal direction can be easily realized. The flow rate of the gas introduced into the plasma gas supply pipe 10 is controlled by providing a flow rate control device such as a mass flow controller upstream thereof.

  The plasma gas supply hole 11 is a long slit, but a plurality of round holes may be provided in the longitudinal direction.

  The central axis of the solenoid coil 27 is arranged so as to coincide with the central axis of the long chamber and the central axis of the plasma ejection port 8. This central axis is a broken line shown in FIGS. 3 (a) and 3 (b).

  Further, a shield gas nozzle 13 as a shield gas supply port is disposed in a portion close to the substrate mounting table 1, and a shield gas manifold 14 is provided therein. In this way, two systems of gas introduction are prepared, and a shielding gas is supplied in addition to the plasma gas suitable for plasma generation, such as oxygen and carbon dioxide in the atmosphere, which are unnecessary or have an adverse effect on the processing. It is possible to reduce contamination of the plasma irradiation surface. The shield gas supply port may be a slit having a shape that is long in a direction parallel to the long direction of the plasma outlet 8, or may be in a direction parallel to the long direction of the plasma outlet 8. It may be a number of holes arranged side by side.

  The solenoid coil 27 is provided in the refrigerant flow path 15, and the refrigerant flow path 15 includes a space surrounded by the refrigerant case 16, the refrigerant flow path lid 26, and the quartz tube 28. A plurality of taps 18 are joined to the surface forming the inner wall surface of the refrigerant flow path 15 of the quartz tube 28. The tap 18 is made of a dielectric and is selected from quartz, ceramics, resin, and the like. Joining can be performed by using various adhesives in addition to the welding method. A dielectric bolt 19 is screwed into the tap 18 through a through hole provided in the refrigerant case 16. An O-ring is provided between the head of the bolt 19 and the refrigerant case 16. That is, a space surrounded by the quartz tube 28 as a dielectric member and the refrigerant case 16 as a cover arranged outside of these forms a refrigerant flow path, and the quartz tube 28 and the refrigerant case 16 However, it is the structure connected by the tap 18 and the volt | bolt 19 as a support | pillar.

  Further, two taps 20 are provided on the high-frequency power supply unit and the grounding unit of the solenoid coil 27. The tap 20 is made of a conductor and is selected from copper, brass and the like. A conductor-made bolt 21 is screwed into the tap 20 through a through hole provided in the refrigerant case 16. An O-ring is provided between the head of the bolt 21 and the refrigerant case 16. A copper plate (not shown) or the like is sandwiched between the bolt 21 and the refrigerant case 16, and high-frequency wiring is made. A refrigerant, such as cooling water, is introduced into the refrigerant flow path 15 and discharged through a refrigerant pipe (not shown) provided in the refrigerant case 16.

  Note that O-rings are also provided on the contact surfaces of the coolant case 16, the coolant channel lid 26 and the quartz nozzle 29, and the contact surfaces of the coolant channel lid 26 and the quartz tube 28.

  Thus, the cooling water as the coolant flows around the solenoid coil 27 and around the quartz tube 28 and the quartz nozzle 29 which are members constituting the long chamber, and the solenoid coil 27, the quartz tube 28, and the quartz nozzle. 29 cooling is realized.

  Further, by adopting a structure in which the bolt 19 is screwed into the tap 18, the quartz tube 28 and the quartz nozzle 29 are deformed even when a large amount of refrigerant flows and the internal pressure (water pressure) in the refrigerant flow path 15 increases. Hateful. In other words, in the present embodiment, a much larger amount of refrigerant can be allowed to flow than in the case of water-cooling as a double-pipe structure in the technique described in Patent Document 6 shown in the conventional example, and effective cooling is achieved. Is possible. In order to further increase the rigidity, the material and thickness of the refrigerant case 16 can be devised.

  A rectangular slit-shaped plasma ejection port 8 is provided, and the substrate mounting table 1 (or the substrate 2 on the substrate mounting table 1) is disposed to face the plasma ejection port 8. In this state, high-frequency power is supplied to the solenoid coil 27 from a high-frequency power source (not shown) while gas is being injected from the plasma outlet 8 toward the base material 2 while supplying gas into the long chamber. The thin film 22 on the substrate 2 can be plasma-treated by generating plasma in the space 7 inside the long chamber and irradiating the substrate 2 with the plasma from the plasma outlet 8. The base material 2 is processed by relatively moving the long chamber and the base material mounting table 1 in a direction perpendicular to the longitudinal direction of the plasma ejection port 8. That is, the inductively coupled plasma torch unit T or the substrate mounting table 1 is moved in the left-right direction in FIG. 3A and in the direction perpendicular to the paper surface in FIG.

  Various gases can be used as the gas supplied into the long chamber. However, considering the stability of the plasma, the ignitability, the life of the member exposed to the plasma, etc., it is desirable that the main gas is an inert gas. Among these, Ar gas is typically used. When plasma is generated only by Ar, the plasma becomes considerably high temperature (10,000 K or more).

  In this configuration, since the length in the longitudinal direction of the plasma outlet 8 is equal to or larger than the width of the base material 2, a single scan (the inductively coupled plasma torch unit T and the base material mounting table 1 is performed). The entire thin film 22 in the vicinity of the surface of the substrate 2 can be processed by relatively moving).

In such a plasma processing apparatus, a high-frequency power source (not shown) is supplied while Ar or Ar + H ₂ gas is supplied from a gas outlet into a long chamber and gas is jetted from the plasma outlet 8 toward the substrate 2. Further, by supplying high frequency power of 13.56 MHz to the solenoid coil 27, plasma is generated by generating a high frequency electromagnetic field in the space 7 inside the long chamber, and the plasma is supplied from the plasma outlet 8 to the substrate 2. By performing irradiation and scanning, heat treatment such as crystallization of a semiconductor film can be performed.

As conditions for plasma generation, the distance between the plasma jet port 8 and the substrate 2 = 3 to 50 mm, the scanning speed = 50 to 3000 mm / s, the total plasma gas flow rate = 1 to 100 SLM, the H ₂ concentration in Ar + H ₂ gas = 0-10%, shielding gas (N ₂₎ flow rate = 1～100SLM, a value of about RF power = 0.5～10KW appropriate. However, among these quantities, the gas flow rate and power are values per 100 mm of the length of the plasma jet port 8. This is because it is considered appropriate to input parameters proportional to the length of the plasma jet port 8 for parameters such as gas flow rate and electric power.

  As described above, the long chamber and the substrate mounting table 1 are arranged in a direction perpendicular to the longitudinal direction of the plasma nozzle 8 while the longitudinal direction of the plasma nozzle 8 and the substrate mounting table 1 are arranged in parallel. Therefore, the length of the plasma to be generated and the processing length of the substrate 2 can be configured to be substantially equal. The width of the cross section obtained by cutting the long chamber along a plane perpendicular to the central axis thereof (the width of the space 7 inside the long chamber in FIG. 3A) is the width of the plasma outlet 8 (FIG. 3A It may be a little larger than the width of the gap). That is, the volume of plasma to be generated can be made extremely small compared to the conventional one. As a result, power efficiency is dramatically increased.

(Embodiment 3)
Hereinafter, a third embodiment of the present invention will be described with reference to FIG.

  FIG. 5 shows the configuration of the plasma processing apparatus according to the third embodiment of the present invention, which is an assembly configuration diagram of the inductively coupled plasma torch unit, in which perspective views of parts (part) are arranged.

  In the second embodiment, the cylindrical member is joined to the surface forming the inner wall surface of the refrigerant flow path 15 of the quartz tube 28, and the tap 18 is provided on the cylindrical member. However, in the third embodiment, FIG. As shown, a columnar member 30 is joined to the surface of the quartz tube 28 that forms the inner wall surface of the coolant channel 15, and a plurality of taps 18 are provided on one columnar member 30.

  With such a configuration, the rigidity of the quartz tube 28 in the longitudinal direction is increased, so that a larger amount of refrigerant can be flowed and effective cooling can be realized.

  The plasma processing apparatus and method described above merely exemplify typical examples of the scope of application of the present invention.

  For example, the inductively coupled plasma torch unit T may be scanned with respect to the fixed substrate mounting table 1, but the substrate mounting table 1 is scanned with respect to the fixed inductively coupled plasma torch unit T. May be.

  Moreover, although the case where the spiral coil 3 was planar was illustrated, the spiral coil 3 does not necessarily need to be a plane. For example, a configuration using a so-called bell-shaped spiral coil in which the distance between the spiral coil 3 and the first quartz plate 4 gradually increases toward the center of the vortex.

  Moreover, although the case where the plasma jet port 8 is provided on the opposite side to the spiral coil 3 in the long chamber is illustrated, the direction from the plasma jet port 8 to the long chamber and the long length from the spiral coil 3 are illustrated. The configuration may be such that the directions to the chambers are perpendicular to each other.

  In addition, the various configurations of the present invention enable high-temperature treatment of the vicinity of the surface of the base material 2, but for crystallization of a TFT semiconductor film and modification of a solar cell semiconductor film described in detail in the conventional example. Of course, it can be applied to cleaning and reducing degassing of the protective layer of plasma display panels, flattening and reducing degassing of dielectric layers composed of aggregates of silica particles, reflow of various electronic devices, solid impurities It can be applied to various surface treatments such as plasma doping using a source. Moreover, as a manufacturing method of a solar cell, it can apply also to the method of apply | coating the powder obtained by grind | pulverizing a silicon ingot on a base material, and irradiating this with a plasma and fuse | melting it, and obtaining a polycrystalline silicon film.

  It is also possible to use an ignition source in order to facilitate plasma ignition. As an ignition source, an ignition spark device used for a gas water heater or the like can be used.

  In the description, the term “thermal plasma” is used for simplicity. However, it is difficult to distinguish between thermal plasma and low temperature plasma. For example, Tanaka Yasunori “Non-equilibrium in thermal plasma” plasma nucleus Journal of Fusion Society, Vol. 82, no. 8 (2006) p. As described in 479-483, it is also difficult to classify plasma types based on thermal equilibrium alone. The present invention has an object of heat-treating a substrate, and can be applied to a technique for irradiating high-temperature plasma without being bound by terms such as thermal plasma, thermal equilibrium plasma, and high-temperature plasma.

In addition, the case where high-temperature heat treatment is performed in the vicinity of the surface of the base material uniformly for a very short time is illustrated in detail. The present invention can also be applied. By mixing the reaction gas with the plasma gas, the plasma by the reaction gas is irradiated onto the substrate, and etching and CVD can be realized. Alternatively, the plasma and the reactive gas flow are simultaneously irradiated onto the substrate by supplying a gas containing a reactive gas as a shielding gas while using a rare gas or a gas obtained by adding a small amount of H ₂ gas to the rare gas as the plasma gas. In addition, plasma processing such as etching, CVD, and doping can be realized.

When a gas containing argon as a main component is used as the plasma gas, thermal plasma is generated as exemplified in detail in the embodiment. On the other hand, when a gas containing helium as a main component is used as the plasma gas, a relatively low temperature plasma can be generated. By such a method, processing such as etching and film formation can be performed without heating the substrate too much. Examples of the reactive gas used for etching include a halogen-containing gas such as C _x F _y (x and y are natural numbers), SF _{6, and the} like, and silicon and silicon compounds can be etched.

If O ₂ is used as the reaction gas, it is possible to remove organic substances, resist ashing, and the like. The reactive gas used for CVD includes monosilane, disilane, and the like, and silicon or silicon compound can be formed. Alternatively, a silicon oxide film can be formed by using a mixed gas of O ₂ and an organic gas containing silicon typified by TEOS (Tetraethoxysilane). In addition, various low-temperature plasma treatments such as surface treatment for modifying water repellency and hydrophilicity are possible. Compared to the prior art (for example, described in Patent Document 7), since it is an inductive coupling type, even if a high power density per unit volume is applied, it is difficult to shift to arc discharge, so a higher density plasma is generated. As a result, a high reaction rate can be obtained, and the entire desired region to be treated of the substrate can be processed in a short time.

  As described above, the present invention can be applied to crystallization of a TFT semiconductor film and modification of a solar cell semiconductor film. Of course, cleaning of the protective layer of the plasma display panel and reduction of degassing, surface flattening and reduction of degassing of the dielectric layer consisting of aggregates of silica fine particles, reflow of various electronic devices, plasma doping using a solid impurity source In various surface treatments and the like, the present invention is useful in treating the entire desired region of the substrate in a short time when the vicinity of the surface of the substrate is uniformly subjected to high temperature heat treatment for a very short time.

  In addition, it is a useful invention for processing a desired whole region of a substrate in a short time in low temperature plasma processing such as etching, film formation, doping, and surface modification in manufacturing various electronic devices. .

DESCRIPTION OF SYMBOLS 1 Substrate mounting base 2 Substrate T Inductively coupled plasma torch unit 3 Spiral coil 4 First quartz plate 5 Second quartz plate 6 Third quartz plate 7 Space inside long chamber 8 Plasma outlet 9 Plasma gas manifold 11 Plasma Gas supply hole 13 Shield gas nozzle 14 Shield gas manifold 15 Refrigerant flow path 16 Refrigerant case 17 Refrigerant case 18 Tap 19 Bolt 20 Tap 21 Bolt 22 Thin film

Claims (12)

A long and linear opening; and a long chamber having a long shape in a direction parallel to the longitudinal direction of the opening, the long chamber communicating with the opening, and surrounded by a dielectric member; A gas supply pipe for introducing gas into the long chamber, a coil having a long shape in a direction parallel to the longitudinal direction of the opening, a high-frequency power source connected to the coil, and a base material In the apparatus provided with a moving mechanism that enables the mounting table and the chamber and the base material mounting table to move relative to each other in a direction perpendicular to the longitudinal direction of the opening,
A space surrounded by the dielectric member and a cover disposed outside the dielectric member constitutes a refrigerant flow path, and the dielectric member and the cover are connected by a column. ,
A plasma processing apparatus. The plasma processing apparatus according to claim 1, wherein the coil forms a spiral coil having one spiral shape as a whole. The plasma processing apparatus according to claim 2, wherein the spiral coil is planar. The plasma processing apparatus according to claim 3, wherein an inner wall surface of the chamber close to the spiral coil is a plane parallel to a plane formed by the spiral coil. The plasma processing apparatus according to claim 2, wherein the chamber is configured as a space sandwiched between two dielectric plates each having a groove. The plasma processing apparatus according to claim 2, wherein an outer shape of the chamber is larger than an outer shape of the spiral coil. The depth of the chamber is 0.5 mm or more and 7 mm or less when defined as “depth of the chamber” = “length of the chamber in the direction from the spiral coil to the chamber”. Plasma processing equipment. The plasma according to claim 2, wherein the depth of the chamber is 1 mm or more and 5 mm or less when defining "depth of the chamber" = "length of the chamber in the direction from the spiral coil to the chamber". Processing equipment. The plasma processing apparatus according to claim 2, wherein the opening is provided in the chamber on a side opposite to the spiral coil. The plasma processing apparatus according to claim 2, wherein a direction from the opening to the chamber and a direction from the spiral coil to the chamber are perpendicular to each other. The plasma processing apparatus according to claim 1, wherein the coil is disposed so as to surround the chamber and has a single solenoid shape as a whole. While supplying gas into the long chamber surrounded by the dielectric member, the gas is ejected from the slit-shaped opening formed in the chamber toward the base material, and the direction parallel to the longitudinal direction of the chamber A plasma processing method for generating a high-frequency electromagnetic field in the chamber by supplying high-frequency power to a coil having a long shape,
While allowing the coolant to flow in a space surrounded by the dielectric member and the cover disposed outside the dielectric member, which are connected to each other by struts,
Treating the surface of the substrate while relatively moving the chamber and the substrate in a direction perpendicular to the longitudinal direction of the opening;
A plasma processing method characterized by the above.

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