JP2006019067A - Plasma treatment device and plasma treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treatment device in which substitution of gas can be carried out within a very short period of time. <P>SOLUTION: This plasma treatment device is equipped with a gas supplying means to supply desired gas to a plasma generating space 16 that is under a pressure near the atmospheric pressure, three or more electrodes 5a, 5b, 5c in order to generate the plasma 8 in the plasma generating space 16, a power source 6 for impressing voltages on one or more voltage impressing target electrodes selected from the three or more electrodes in order to generate the plasma 8 in the plasma generating space 16, and a switching circuit 7 as a switching means of voltage impressing state in order to switch selection of the voltage impressing target electrode so that a first generating region and a second generating region will be switched wherein regions in which the plasma 8 is generated in the plasma generating space 16 are different from each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a plasma processing apparatus and a plasma processing method that can be applied to the manufacture of, for example, semiconductor devices, liquid crystal display devices, and solid-state imaging devices. Examples of the plasma processing apparatus include a plasma CVD apparatus and a plasma etching apparatus. These plasma processing apparatuses may be applied to processes such as forming a thin film on a substrate that is an object to be processed and etching a substrate or a thin film formed on the substrate.

  Conventionally, in a plasma processing apparatus, as a result of using a chemical reaction by plasma, there is a problem that a polymer film of a reaction product or a reaction gas adheres to the surface of an apparatus component around the plasma generation region. In order to eliminate the performance deterioration due to the deposits, in the plasma processing apparatus, an operation of removing the reaction product or the polymer film using the active species generated by the plasma discharge, that is, an operation called “dry cleaning” is performed. .

  For example, Japanese Patent Laid-Open No. 6-53176 (Patent Document 1) shows an apparatus capable of performing dry cleaning. Japanese Patent Application Laid-Open No. H10-228688 discloses switching of an electrode to which a voltage is applied between a step of performing dry etching, which is a plasma treatment, and a step of performing dry cleaning.

  Hereinafter, the configuration and operation of the conventional apparatus disclosed in Patent Document 1 will be described with reference to FIGS. 14 and 15. The reaction chamber space 112 defined by the reaction chamber wall 111 is kept in a vacuum by an external exhaust pump. Inside the reaction chamber space 112, there are a wafer holding electrode 113 that serves both as holding of the wafer 116 and a discharge electrode, a counter electrode 114, and an inner wall electrode 115 that is in close contact with the reaction chamber wall 111. The reaction chamber wall 111 is electrically grounded. Wafer holding electrode 113, counter electrode 114, inner wall electrode 115, and reaction chamber wall 111 are electrically insulated from each other. Wafer holding electrode 113, counter electrode 114, and inner wall electrode 115 are each connected to selection switch 117 by a coaxial cable. The selection switch 117 is used to connect the wafer holding electrode 113, the counter electrode 114, and the inner wall electrode 115 independently to the high frequency power source 119 via the high frequency matching unit 118 or to a ground circuit.

  In the above-described configuration, first, in the dry etching process, an etching reactive species generation gas is introduced into the reaction chamber space 112. Then, after the pressure is reduced to a predetermined level by an external exhaust pump, as shown in FIG. 14, the wafer holding electrode 113 is connected to the high frequency power source via the high frequency matching unit 118 by the selection switch 117 and the counter electrode 114 and the inner wall electrode 115 are grounded. Connect to the circuit.

  In the dry cleaning step, a dry cleaning gas is introduced into the reaction chamber space 112. Then, after reducing the pressure to a predetermined level by an external exhaust pump, the wafer holding electrode 113 and the counter electrode 114 are set to the ground circuit by the selection switch 117 and the inner wall electrode 115 is set to the high frequency via the high frequency matching unit 118 as shown in FIG. Connect to power supply 119.

  By switching the electrodes in this way, plasma discharge regions can be formed in the corners of the reaction chamber wall 111 and the outer edge portions of the wafer holding electrode 113 and the counter electrode 114 in the dry cleaning process. For this reason, it becomes possible to remove the reaction product and polymer adhering to the said location in the dry etching process by the dry cleaning process.

Note that Patent Document 1 describes the use of dry etching, but effective dry cleaning by changing the discharge region in this way is the same in a film forming method such as a plasma CVD method. is there.
JP-A-6-53176

  When performing the cleaning process using the apparatus disclosed in Patent Document 1, there are the following problems.

That is, in the apparatus disclosed in Patent Document 1, normally, a sufficient time is secured as a processing time for the dry cleaning process, and the dry cleaning process is performed after the dry etching process is completed. In order to perform the dry cleaning process, it is necessary to replace the gas atmosphere. This work is detailed
a) Stop supply of gas for generating reactive species of etching,
b) The reaction chamber space is evacuated to vacuum by an exhaust pump.
c) start supplying dry cleaning gas,
d) controlling the gas supply / exhaust to a predetermined gas pressure;
It is divided into the steps. In particular, since the vacuum evacuation step of b) is necessary for a long time, if the dry cleaning process is frequently performed, the operating rate of the apparatus is lowered, which becomes a problem related to productivity.

  However, on the other hand, if the plasma treatment is continuously performed, the amount of the reaction product and polymerized film already described increases, which causes problems such as generation of particles and deterioration of reproducibility of the plasma treatment. . Therefore, it is desirable to frequently perform dry cleaning in order to maintain good plasma processing characteristics.

  In view of these problems, the present invention provides an apparatus that can perform gas replacement in an extremely short time, and also provides a method that allows frequent dry cleaning without reducing the operating rate of the apparatus. The purpose is to do.

  In order to achieve the above object, a plasma processing apparatus according to the present invention comprises a gas supply means for supplying a desired gas to a plasma generation space under a pressure near atmospheric pressure, and a plasma in the plasma generation space. For applying a voltage to three or more electrodes for generating a voltage and one or more electrodes selected from among the three or more electrodes for generating plasma in the plasma generation space. And a voltage for switching the selection of the voltage application target electrode so that the plasma generation region in the plasma generation space is switched between the first generation region and the second generation region which are different from each other. Application state switching means.

  Preferably, in the above invention, when an electrode to which the highest voltage is applied among the electrodes belonging to the three or more electrodes in a state where a voltage is applied to the voltage application target electrode by the power source is referred to as a highest potential electrode, The voltage application state switching means has a choice of voltage application patterns that can set any of the three or more electrodes as the highest potential electrodes.

  Preferably, in the above invention, gas supply path switching means for switching a path through which the gas is supplied to the plasma generation space in accordance with switching of a region where the plasma is generated in the plasma generation space is provided.

  Preferably, in the above invention, two or more of the three or more electrodes each have a facing surface that faces a passage path of the object to be processed, and the first generation region is mutually connected among the three or more electrodes. It is a gap between adjacent electrodes, and the second generation region is in the vicinity of the facing surface.

  Preferably, in the above invention, the three or more electrodes each have a facing surface facing the passage of the object to be processed, and the three or more electrodes include two electrodes arranged with one or more electrodes interposed therebetween. The voltage application state switching means can set the selection of the voltage application target electrode so as to generate plasma in the vicinity of the facing surface by forming an electric field between the two electrodes.

  Preferably, in the above invention, two or more of the three or more electrodes each have a facing surface that faces the passage path of the workpiece, and faces the facing surface across the passage path of the workpiece. And the voltage application state switching means generates the plasma in the vicinity of the facing surface by forming an electric field between the electrode having the facing surface and the auxiliary electrode. Selection of the voltage application target electrode can be set.

  Preferably, in the above invention, the minimum interval in the thickness direction of the plasma generation space is large enough to cause the gas to behave as a viscous flow, and the first gas is retained in the plasma generation space. By flowing the second gas into the plasma generation space, the first gas occupied in the plasma generation space is swept away with the second gas and replaced.

  In the present invention, preferably, the minimum distance d in the thickness direction in the plasma generation space satisfies the relationship of λ <0.0002d with respect to the mean free path λ of the gas molecules.

  Preferably, in the above invention, an object supply means for supplying the object to be processed is provided so that the object to be processed passes through a space where plasma processing is performed.

  Preferably, in the above invention, the voltage application state switching means changes the selection of the voltage application target electrode in accordance with the timing at which the workpiece is supplied.

  Preferably, in the above invention, the gas supply means changes the type of gas supplied to the plasma generation space in accordance with the timing at which the workpiece is supplied.

  In order to achieve the above object, in one aspect of the plasma processing method according to the present invention, the object to be processed is passed while the object to be processed passes through the plasma generation space using any one of the above plasma processing apparatuses. A plasma treatment step for performing a desired plasma treatment on an object, and a portion of the electrode facing the plasma generation space before the object to be processed enters the plasma generation space or after it exits the plasma generation space. And a cleaning process for performing cleaning.

In order to achieve the above object, in another aspect of the plasma processing method according to the present invention, the object to be processed is passed through the plasma generation space using any one of the above plasma processing apparatuses. A plasma treatment process for performing a desired plasma treatment on an object;
Cleaning for cleaning a portion of the electrode facing the plasma generation space between the time when the first object to be processed leaves the plasma generation space and the time when the second object to be processed enters the plasma generation space. Process.

  According to the present invention, it is possible to perform gas replacement in a very short time. As a result, since dry cleaning can be performed using the existing dead time, it is possible to frequently perform dry cleaning without reducing the operating rate of the apparatus.

(Embodiment 1)
(Constitution)
With reference to FIG. 1 and FIG. 2, the plasma processing apparatus in Embodiment 1 based on this invention is demonstrated. The plasma processing apparatus includes a reaction vessel 1 and a gas cylinder 2 which is a gas supply source for supplying a desired gas to a plasma generation space 16 defined inside the reaction vessel 1. The reaction vessel 1 and the gas cylinder 2 are connected by a gas pipe 21. A gas flow meter 3 for monitoring the flow rate of the gas to be supplied and controlling it as necessary is disposed in the middle of the gas pipe 21. And an opening / closing valve 4 for opening and closing. In this plasma processing apparatus, a part of the reaction vessel 1 is constituted by an insulator 1a. Three rectangular bar-shaped electrodes having a substantially triangular cross section, that is, a first electrode 5a, a second electrode 5b, and a third electrode 5c are arranged substantially in parallel so as to be fixed to the insulator 1a. ing. Of these three electrodes, only the second electrode 5b is arranged upside down as shown in FIG. Although the number of these electrodes should just be three or more, it demonstrates on the assumption that the number of electrodes is three here.

  When the plasma generation space 16 defined by being surrounded by the first electrode 5a, the second electrode 5b, the third electrode 5c, the insulator 1a, and the inner wall of the reaction vessel 1 facing them constitutes a gas flow path. At the same time, it is a passage for the workpiece. The first electrode 5a and the third electrode 5c have opposing surfaces 17a and 17c, respectively, that are opposed to the passage path.

  In this embodiment, since the operation is performed under atmospheric pressure, that is, a pressure of approximately 1 atm, the mean free path of gas molecules is about 0.1 μm. Therefore, the minimum dimension in the thickness direction of the cross section of the gas flow path (hereinafter referred to as “minimum thickness of the gas flow path”) is 0.5 mm so that the introduced gas becomes a sufficiently viscous flow under this operating pressure. That's it. The minimum thickness of the gas flow path is the first electrode 5a, the second electrode 5b, the third electrode 5c, and the insulator 1a constituting the upper wall of the gas flow path, and the lower wall facing these. The dimension of the smallest part of the space between the inner wall 22 of the reaction vessel 1 that constitutes the above.

  Dashman has proposed a method for determining that the gas flow becomes a viscous flow under the condition of λ << 0.01d for the mean free path λ of gas molecules and the minimum thickness d of the gas flow path. In the present invention, not only the gas flow becomes a viscous flow, but also it is intended to quickly purge the gas to replace the gas in the plasma generation space 16, and in order to quickly sweep the gas, λ It is necessary that the condition of <0.0002d is satisfied. An experiment was performed to determine whether or not the substitution was completed by the change in the emission spectrum of the plasma 8. As long as the condition of λ <0.0002d was satisfied, the substitution of the gas in the plasma generation space 16 was completed in a few seconds. Was possible. In the determination experiment performed here, the gas flow rate introduced into the gas flow path is divided by the gas flow path minimum thickness d to calculate the gas flow rate, and the gas flow rate is set to 1 cm / second. It was done. A higher gas flow rate is essential for good plasma processing. Naturally, the gas replacement can be completed at a higher speed by setting a gas flow rate higher than this.

  In the plasma processing apparatus according to the present embodiment, since the substrate 10 needs to be transported, it is desirable to set the minimum gas flow path thickness d to approximately 1 mm or more. Further, considering that the substrate 10 slightly vibrates up and down along with the conveyance, it is desirable to set the minimum gas flow path thickness d to about 3 mm to 5 mm.

  The first electrode 5a, the second electrode 5b, and the third electrode 5c are metal electrodes coated with a dielectric, and are connected to a switching circuit 7 as voltage application state switching means. Each of the electrodes is selected by the switching circuit 7 to be connected to a power source 6 capable of generating a high voltage, grounded, or floated. The power source 6 is for applying a voltage to a voltage application target electrode that is one or more electrodes selected from the above three or more electrodes.

  Further, the plasma processing apparatus includes a substrate transfer device for transferring the substrate 10 that is an object to be processed. However, FIG. 1 shows only the substrate transfer roller 9 which is a component of the substrate transfer apparatus. The substrate 10 is linearly loaded into the reaction vessel 1 from the opening at the right end in the figure, subjected to plasma treatment when passing through the central plasma generation space 16, and then unloaded from the opening at the left end in the figure. The

  2 is a cross-sectional view taken along the line II-II in FIG. In FIG. 2, components related to the gas piping 21 and the electric circuit outside the reaction vessel 1 are not shown.

  As shown in FIG. 2, the reaction vessel 1 is closed with side walls 23 on the left and right sides in the direction of travel of the substrate 10. The reaction vessel 1 has a configuration in which only an opening for carrying in and carrying the substrate 10 is opened to the atmosphere.

  The reaction vessel 1 may be made of a material having corrosion resistance against a desired plasma treatment. Examples of such a material include an aluminum alloy and a stainless alloy. Furthermore, when an aluminum alloy is employed, it is desirable to perform an inner surface treatment such as an alumite treatment on the inner surface of the reaction vessel 1. Alternatively, the alumina coating may be formed by a thermal spraying method or the like. However, the portion for fixing the electrode needs to be composed of the insulator 1a, and it is desirable to use a ceramic material such as alumina or aluminum nitride for this portion.

  The first electrode 5a, the second electrode 5b, and the third electrode 5c are made of metal. The material of these electrodes may be an aluminum alloy or a stainless alloy. If necessary, a cooling water channel may be provided in each electrode in order to suppress a temperature rise when the plasma 8 is generated, and a function of cooling the electrode with cooling water may be provided. The surface of these electrodes is preferably coated with a dielectric, and a dielectric coating such as alumina is formed by thermal spraying, or a ceramic sintered body such as alumina is formed to cover the electrode surface. It may be integrated with.

  In addition, although each electrode shown in FIG. 1 has shown the example whose cross section is a substantially triangular shape, this invention is not limited to this, For example, a cross section has a substantially pentagonal shape etc. May be.

  The power source 6 only needs to have a function capable of applying a high voltage of about 1 kV or higher. However, in order to stably discharge the plasma 8, a power source 6 having a frequency of about 1 kHz to 300 MHz is adopted. Is desirable. If the frequency is 1 kHz or less, it is difficult to maintain a stable discharge, and if it exceeds 300 MHz, it is difficult to design an electric circuit system. Further, as the frequency increases, the gap necessary to maintain a stable glow discharge becomes narrower. When the frequency exceeds 300 MHz, a stable glow discharge can be formed only with a narrow gap of about 200 μm, and it becomes difficult to configure the reaction vessel 1 while maintaining a uniform gap in the longitudinal direction of the electrode.

(Plasma treatment process)
First, in the plasma processing apparatus according to the present embodiment, a step of performing a desired plasma process on the object to be processed while the object to be processed passes through the plasma generation space, that is, an operation, action, and effect of the plasma processing process will be described. . In the plasma processing apparatus according to the present embodiment, for example, when a CVD film is formed on the substrate 10 or when etching is performed, such as when etching is performed, the gas pipe 21 and the gas supply path 18 are connected from the gas cylinder 2. Then, a plasma processing gas is introduced into the plasma generation space 16. It is desirable that the plasma processing gas contains at least a reactive gas for plasma processing, and is further mixed with a rare gas that can easily maintain stable plasma discharge. Of course, as long as stable discharge can be maintained with only the reactive gas, the above rare gas may not be mixed, and oxygen, water, and other gases may be added thereto, and an appropriate gas may be selected as appropriate. Good.

  As described above, the reaction vessel 1 is a system opened to the atmosphere through an opening. In such a system, the atmosphere, that is, a gas mainly composed of oxygen and nitrogen is mixed into the reaction vessel 1, but the area of the opening is made as small as possible and a sufficient amount of plasma processing gas is supplied. Therefore, it is possible to suppress the influence of air contamination.

  By performing the above-described operation, a desired gas atmosphere is formed at least in a region intended for plasma discharge in the reaction vessel 1, and the first electrode 5a and the third electrode 5c are switched by the switching circuit 7 as shown in FIG. Is connected to ground, and the second electrode 5 b is connected to the power source 6. A high voltage is applied to the second electrode 5b by the power source 6. As a result, in the plasma generation space 16, the region in the vicinity of the insulator 1a, and between the first electrode 5a and the second electrode 5b and between the second electrode 5b and the third electrode 5c. Plasma 8 is generated in the area between. At this time, a region where the plasma 8 is generated is assumed to be a “first generation region”. In such a state where the plasma discharge is maintained, the substrate 10 is moved by the substrate transfer device as shown in FIG. 1 and passed through the region where the plasma 8 is generated, so that the desired region or the entire surface of the substrate 10 is applied. Then, it becomes possible to perform the desired plasma processing by sequentially reacting the reactive species in the plasma 8.

  In FIG. 1, the direction of substrate conveyance is leftward in the figure, but this is only an example, and the substrate may be conveyed rightward in the figure. In the structure of FIG. 1, when the substrate is transported to the right in the drawing, the gas flow flows in a direction opposite to the substrate transport direction, so that the amount of outside air accompanying the substrate accompanying the substrate transport is suppressed. There is. On the other hand, when the substrate is transported leftward in the figure, the gas flow is the same as the direction of substrate transport, and there is an effect of suppressing the turbulence of the gas flow at the substrate edge portion accompanying the substrate loading.

(Cleaning process)
Next, in the plasma processing apparatus according to the present embodiment, a step of cleaning a portion of the electrode facing the plasma generation space before the processing object enters the plasma generation space or after exiting from the plasma generation space, That is, the operation, action, and effect of the cleaning process will be described. When the substrate 10 finishes passing through the plasma generation space 16 and the plasma processing is completed, as shown in FIG. 3, the switching circuit 7 is switched, the first electrode 5a is connected to the power source 6, and the second electrode 5b is not connected, and the third electrode 5c is grounded. At the same time as the supply of the plasma processing gas is stopped, the supply of the cleaning gas is started without going through a gas exhaust step using an exhaust pump or the like. The cleaning gas is also supplied from the gas cylinder 2 through the gas pipe 21 and the gas supply path 18.

  In this state, by applying a high voltage to the first electrode 5a, plasma 8 is generated in the vicinity of the lower surface from the first electrode 5a to the third electrode 5c. At this time, a region where the plasma 8 is generated is assumed to be a “second generation region”. The second generation region is a region different from the first generation region. Switching of these plasma generation regions is performed by switching the selection of the voltage application target electrode by the switching circuit 7 as voltage application state switching means. As a result, it is possible to clean the portion in contact with the plasma 8 generation region and the vicinity thereof on the lower surface of the first electrode 5a, the second electrode 5b, the third electrode 5c, and the insulator 1a.

(Process switching)
The timing of substrate loading can be easily grasped by detecting the substrate position using, for example, an optical sensor. Therefore, a system is provided that detects the time immediately before or after the substrate 10 is carried in by some detection means, sends an electrode switching command to the switching circuit 7, and sends a change command of the type of gas to be introduced to the gas flow meter 3. Thus, it is possible to automatically switch between the plasma processing process and the cleaning process.

  According to the plasma processing apparatus in the present embodiment, the gas flow path is formed so as to include the plasma generation space 16, and the gas flow path is designed so that the gas becomes a sufficiently viscous flow. The previously used plasma processing gas is pushed out by the cleaning gas. As a result, the rate at which the plasma processing gas remains in at least the region intended for plasma discharge for dry cleaning in the reaction vessel 1 is drastically reduced and can be quickly replaced with a cleaning gas atmosphere. Become. Therefore, dry cleaning can be performed promptly after the plasma processing on the substrate 10 is completed and the substrate 10 is unloaded. Further, after the dry cleaning is completed, the gas to be introduced is changed from the cleaning gas to the plasma processing gas, and when the electrodes are switched, preparation for performing the desired plasma processing is quickly made again.

  In general, in a so-called “single-wafer type” plasma processing apparatus that is supplied by being transported so that the substrate to be processed sequentially passes through the space for plasma processing, a transport path including the substrate transport apparatus is constructed. In this case, a dead time of about 30 seconds or more occurs after the first substrate is transferred and before the next second substrate is transferred. FIG. 4 shows the relationship between the time during which plasma processing is actually performed and the dead time. Thus, a dead time always exists between one plasma process and the next plasma process. Further, considering that the time required for each plasma treatment is approximately 60 seconds or less, the dead time of each time is about 30 seconds or more, which is the time occupied by the dead time compared to the time spent for the plasma treatment. It can be seen that the ratio of is relatively large. In addition, the plasma processing apparatus of the prior art cannot perform any plasma processing during this dead time, and cannot perform work related to production.

  On the other hand, in the plasma processing apparatus according to the present invention, the replacement of the plasma processing gas with the cleaning gas or the replacement of the cleaning gas with the plasma processing gas is completed in about 5 seconds. It is possible to perform dry cleaning for about 20 seconds within a dead time range given for 2 seconds. Further, since the dead time can be surely performed between the plasma treatments as described above, the apparatus can be operated with the plasma treatment and the dry cleaning immediately after the plasma treatment as a set. Therefore, dry cleaning can be performed effectively. As a result of cleaning being performed each time the plasma treatment is performed, deposits do not accumulate in the reaction vessel, and it is possible to perform a plasma treatment with excellent reproducibility.

(Example of a configuration in which the reaction vessel is sealed)
By the way, although the structure shown in FIGS. 1-3 is the structure by which the reaction container 1 was open | released by air | atmosphere, the reaction container 1 may be sealed space. FIG. 5 shows an apparatus configuration example in which the opening on the side wall of the reaction vessel 1 is eliminated. In this apparatus, the substrate 10 is placed on a substrate holder 14. In this apparatus, the substrate holder 14 on which the substrate 10 is placed moves instead of the substrate 10 being transported alone by the substrate transporting roller 9. Further, the side wall of the reaction vessel 1 does not have an opening that is always open, but a gate valve 15 is arranged instead. The gate valve 15 can be opened and closed at an arbitrary timing. Further, this configuration includes an exhaust pump 11, a flow rate adjusting valve 12 for adjusting the exhaust amount, and a pressure gauge 13. With these configurations, the inside of the reaction vessel 1 can be set to a desired pressure. Although not shown, if the flow meter 3 is arranged in the middle of the gas pipe 21 at a position closest to the reaction vessel 1, the gas replacement can be completed in a shorter time.

  Of course, even in the configuration in which the reaction vessel 1 is opened to the atmosphere as shown in FIGS. 1 to 3, the gas exhaust function as described above may be provided. It can be done quickly.

(Embodiment 2)
(Constitution)
With reference to FIG. 6, the plasma processing apparatus in Embodiment 2 based on this invention is demonstrated. The description of the same parts as those in the first embodiment will not be repeated. In the present embodiment, a gas supply path 19 is formed in the insulator 1a. There is a gap communicating between the electrodes from the gas supply path 19. Gas introduced from the gas supply path 19 passes through the space 16ab between the first electrode 5a and the second electrode 5b and the space 16bc between the second electrode 5b and the third electrode 5c. It becomes a gas flow path. In the present embodiment, the spaces 16ab and 16bc are also part of the plasma generation space 16. The widths of the spaces 16ab and 16bc are gradually narrowed toward the exit.

  A gas supply path 18 is also formed on the side of the first to third electrodes 5a, 5b, 5c, and it is determined whether the gas is introduced from either of the gas supply paths 18, 19 by operating the opening / closing valve 4. You can choose by. That is, the opening / closing valve 4 is provided as a gas supply path switching means for switching a path through which a gas is supplied to the plasma generation space 16 in accordance with switching of a region where the plasma 8 is generated in the plasma generation space 16.

(Operation)
The operation of the plasma processing apparatus in the present embodiment will be described with reference to FIGS. As shown in FIG. 6, the plasma processing gas is introduced through the gas supply path 19 so that the spaces 16ab and 16bc between the electrodes serve as gas flow paths, and the first electrode 5a and the third electrode 5c. Is connected to ground, and the second electrode 5 b is connected to the power source 6. Then, by applying a high voltage to the second electrode 5b, the plasma 8 is generated particularly in a region sandwiched between the electrodes in the spaces 16ab and 16bc. In this state, the reactive species in the plasma 8 are transferred to the substrate 10 by the gas flow formed by introducing the plasma processing gas, and a desired plasma processing is performed.

  However, during this desired plasma treatment, deposits such as reaction products and polymers are formed around the lower surface regions of the first electrode 5a, the second electrode 5b, and the third electrode 5c. Therefore, as shown in FIG. 7, after the plasma processing on the substrate 10 is completed and the substrate 10 is unloaded from the plasma generation region, the cleaning processing is performed.

  First, supply of the plasma processing gas is stopped by the opening / closing valve 4, and at the same time, supply of the cleaning gas is started. Further, the cleaning gas is supplied from the gas supply path 18 formed on the side of the first to third electrodes 5a, 5b, 5c by the operation of the opening / closing valve 4. Next, for example, the first electrode 5a is connected to the power source 6, the second electrode 5b is electrically floated, and the third electrode 5c is grounded. Then, by applying a high voltage to the first electrode 5a, plasma 8 is generated in a region near the lower surface from the first electrode 5a to the third electrode 5c. Thus, since the plasma 8 for the purpose of dry cleaning is generated around the region where the deposit is formed, dry cleaning can be performed effectively.

  In the present embodiment, not only the plasma generation region is changed by switching the switching circuit 7, but also the gas supply path is changed. Therefore, the gas flow path of the cleaning processing gas is intended for dry cleaning. The plasma generation region can be formed so as to cover a wider area. Therefore, at least in the region covered by the gas flow path, the replacement of the plasma processing gas with the cleaning processing gas can be performed quickly.

(Embodiment 3)
(Constitution)
With reference to FIG. 8, the plasma processing apparatus in Embodiment 2 based on this invention is demonstrated. The description that overlaps with the first and second embodiments will not be repeated. In the present embodiment, the cross-sectional shapes of the first to third electrodes 5a, 5b, 5c are substantially square. And the 4th electrode 5d is arrange | positioned as an auxiliary electrode so as to oppose each opposing surface 17a, 17b, 17c of the 1st-3rd electrodes 5a, 5b, 5c arrange | positioned substantially parallel. The fourth electrode 5d has a flat upper surface 20.

(Operation)
In the plasma processing step shown in FIG. 8, the fourth electrode 5d does not contribute to plasma generation. In contrast, in the dry cleaning process shown in FIG. 9, a high potential is applied to the first to third electrodes 5a, 5b, and 5c, and as a result, plasma is generated between these electrodes and the fourth electrode 5d. 8 occurs. As a result, the opposing surfaces 17a, 17b, and 17c of the first to third electrodes 5a, 5b, and 5c, the upper surface 20 of the fourth electrode 5d, and deposits on the periphery thereof can be effectively removed. .

(Action / Effect)
In the present embodiment, the first to third electrodes 5a, 5b, 5c have a substantially quadrangular cross-sectional shape, so that each electrode can be manufactured relatively easily. In the present embodiment, the fourth electrode 5d that is not originally required for the plasma treatment that is originally desired needs to be separately arranged as an auxiliary electrode. However, in the cleaning process, there is an advantage that the plasma 8 can be generated particularly in a wide range. is there. Further, since the fourth electrode 5d is specified only for dry cleaning, there is an advantage that the arrangement and shape of the fourth electrode 5d are not limited for the originally desired plasma processing and can be designed relatively freely.

(Embodiment 4)
(Constitution)
With reference to FIG. 10, the plasma processing apparatus in Embodiment 4 based on this invention is demonstrated. The description overlapping with the first to third embodiments will not be repeated. The present embodiment is similar to the third embodiment, but there is no fourth electrode.

(Operation)
In the present embodiment, when the originally desired plasma processing, that is, the plasma processing step is performed, the first electrode 5a and the third electrode 5c are grounded, for example, as shown in FIG. A high voltage is applied to the electrode 5b to generate plasma 8. Next, after the plasma treatment is completed, a cleaning gas is introduced into the reaction vessel 1, and the second electrode 5b is grounded as shown in FIG. 11, and a high voltage is applied to the first electrode 5a and the third electrode 5c. Is applied to generate plasma for the purpose of dry cleaning. That is, a cleaning process is performed.

  Here, when the state in the plasma processing step and the state in the dry cleaning step are compared, each electrode is only switched between grounding and high potential application. However, when plasma is generated in the vicinity of the atmospheric pressure, creeping glow discharge spreads particularly around the electrode to which a high potential is applied. Therefore, even if the switching circuit 7 is merely switched in this way, the plasma generation region is reduced. It is possible to change.

  In the form of voltage application as shown in FIG. 10, the plasma 8 does not spread on the left side of the opposing surface 17a of the first electrode 5a and the right side of the opposing surface 17c of the third electrode 5c. In this area, deposits are generated. On the other hand, in the case of the voltage application mode as shown in FIG. 11, the opposing surfaces 17a and 17c of the first electrode 5a and the third electrode 5c are covered with the plasma 8 over the entire area, and the adhering matter is removed. It can be effectively removed. Therefore, if a function of applying a high voltage is provided to each electrode to be used, it is possible to change the plasma generation region in consideration of the expansion of the plasma region due to the creeping glow discharge.

  As a similar example of the embodiment shown in FIG. 11, as shown in FIG. 12, first, a high voltage is applied only to the third electrode 5c, and the periphery of the third electrode 5c is cleaned, as shown in FIG. In addition, it is possible to apply a high voltage only to the first electrode 5a to clean the periphery of the first electrode 5a. What is necessary is just to have a function of applying a high voltage to each electrode. In other words, when the electrode to which the highest voltage is applied among the electrodes belonging to three or more electrodes in a state where the voltage is applied to the voltage application target electrode by the power source 6 is referred to as the highest potential electrode, the voltage application state switching means The switching circuit 7 preferably has a choice of voltage application patterns that can set each of the three or more electrodes to the highest potential electrode. This is because a high voltage can be applied to each of the electrodes to be used, and the plasma generation region can be freely changed so as to cover the lower surface of the desired electrode.

  In addition, the said embodiment disclosed this time is an illustration in all the points, Comprising: It is not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and includes all modifications within the scope and meaning equivalent to the terms of the claims.

It is explanatory drawing of the plasma processing process of the plasma processing apparatus in Embodiment 1 based on this invention. It is arrow sectional drawing regarding the II-II line | wire in FIG. It is explanatory drawing of the cleaning process of the plasma processing apparatus in Embodiment 1 based on this invention. It is explanatory drawing which shows the relationship between the time when plasma processing is actually performed, and the dead time in the conventional plasma processing apparatus. It is sectional drawing of the modification of the plasma processing apparatus in Embodiment 1 based on this invention. It is explanatory drawing of the plasma processing process of the plasma processing apparatus in Embodiment 2 based on this invention. It is explanatory drawing of the cleaning process of the plasma processing apparatus in Embodiment 2 based on this invention. It is explanatory drawing of the plasma processing process of the plasma processing apparatus in Embodiment 3 based on this invention. It is explanatory drawing of the cleaning process of the plasma processing apparatus in Embodiment 3 based on this invention. It is explanatory drawing of the plasma processing process of the plasma processing apparatus in Embodiment 4 based on this invention. It is explanatory drawing of the cleaning process of the plasma processing apparatus in Embodiment 4 based on this invention. It is explanatory drawing which shows the 1st example of the other voltage application form of the plasma processing apparatus in Embodiment 4 based on this invention. It is explanatory drawing which shows the 2nd example of the other voltage application form of the plasma processing apparatus in Embodiment 4 based on this invention. It is 1st explanatory drawing of operation | movement of the plasma processing apparatus based on a prior art. It is 2nd explanatory drawing of operation | movement of the plasma processing apparatus based on a prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Reaction container, 1a insulator, 2 gas cylinder, 3 gas flowmeter, 4 on-off valve, 5a 1st electrode, 5b 2nd electrode, 5c 3rd electrode, 5d 4th electrode, 6 power supply, 7 switching circuit , 8 Plasma, 9 Roller for substrate transfer, 10 Substrate, 11 Exhaust pump, 12 Flow rate adjustment valve, 13 Pressure gauge, 14 Substrate holder, 15 Gate valve, 16 Plasma generation space, 16ab, 16bc (between electrodes) , 17a, 17c Opposing surface, 18, 19 Gas supply path, 20 (Auxiliary electrode) upper surface, 21 Gas piping, 22 Inner wall, 23 Side wall, 111 Reaction chamber wall, 112 Reaction chamber space, 113 Wafer holding electrode, 114 Counter electrode , 115 inner wall electrode, 116 wafer, 117 selection switch, 118 high frequency matching unit, 119 high frequency power source.

Claims (13)

A gas supply means for supplying a desired gas to a plasma generation space under a pressure near atmospheric pressure;
Three or more electrodes for generating plasma in the plasma generation space;
A power supply for applying a voltage to a voltage application target electrode that is one or more electrodes selected from the three or more electrodes to generate plasma in the plasma generation space;
Voltage application state switching means for switching the selection of the voltage application target electrode so that the plasma generation region in the plasma generation space is switched between a first generation region and a second generation region different from each other. A plasma processing apparatus comprising: When an electrode to which the highest voltage is applied among the electrodes belonging to the three or more electrodes in a state where a voltage is applied to the voltage application target electrode by the power source is referred to as a highest potential electrode,
2. The plasma processing apparatus according to claim 1, wherein the voltage application state switching unit has choices of voltage application patterns that can set any of the three or more electrodes to the highest potential electrode.   3. The plasma processing according to claim 1, further comprising gas supply path switching means for switching a path through which the gas is supplied to the plasma generation space in accordance with switching of a region where the plasma is generated in the plasma generation space. apparatus. Of the three or more electrodes, two or more electrodes each have a facing surface facing the passage of the object to be processed.
The first generation region is a gap between adjacent electrodes among the three or more electrodes,
The plasma processing apparatus according to claim 1, wherein the second generation region is in the vicinity of the facing surface.   The three or more electrodes each have a facing surface facing the passage of the object to be processed, and the three or more electrodes include two electrodes arranged with one or more electrodes interposed therebetween, and the voltage application state The switching means can set the selection of the voltage application target electrode so as to generate plasma in the vicinity of the facing surface by forming an electric field between the two electrodes. The plasma processing apparatus as described. Of the three or more electrodes, two or more electrodes each have a facing surface facing the passage of the object to be processed.
An auxiliary electrode arranged to face the facing surface across the passage of the object to be processed;
The voltage application state switching means sets the selection of the voltage application target electrode so as to generate plasma in the vicinity of the opposing surface by forming an electric field between the electrode having the opposing surface and the auxiliary electrode. The plasma processing apparatus according to any one of claims 1 to 5, wherein: The minimum interval in the thickness direction of the plasma generation space is large enough that the gas behaves as a viscous flow,
When the first gas stays in the plasma generation space, the second gas flows into the plasma generation space to cause the first gas occupied in the plasma generation space to flow into the second gas. The plasma processing apparatus according to any one of claims 1 to 6, wherein the plasma processing apparatus is displaced by being washed away. The minimum interval d in the thickness direction of the plasma generation space is relative to the mean free path λ of the gas molecules.
λ <0.0002d
The plasma processing apparatus according to claim 7, satisfying the relationship:   The plasma processing apparatus according to claim 7, further comprising a processing object supply unit configured to supply the processing object so that the processing object passes through a space where plasma processing is performed.   The plasma processing apparatus according to claim 9, wherein the voltage application state switching unit changes the selection of the voltage application target electrode in accordance with a timing at which the workpiece is supplied.   The plasma processing apparatus according to claim 9, wherein the gas supply unit changes a type of gas supplied to the plasma generation space in accordance with a timing at which the workpiece is supplied. A plasma processing step of performing a desired plasma processing on the object to be processed while the object to be processed passes through the plasma generation space using the plasma processing apparatus according to claim 9;
And a cleaning step of cleaning a portion of the electrode facing the plasma generation space before entering the plasma generation space or after exiting the plasma generation space. A plasma processing step of performing a desired plasma processing on the object to be processed while the object to be processed passes through the plasma generation space using the plasma processing apparatus according to claim 9;
Cleaning for cleaning a portion of the electrode facing the plasma generation space between the time when the first object to be processed leaves the plasma generation space and the time when the second object to be processed enters the plasma generation space. And a plasma processing method.

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