Patent Application
20140008326
1. Field of the Invention
The present invention relates to a plasma generation device that generates plasma utilizing a microwave as well as a plasma processing apparatus utilizing the plasma generation device and a plasma processing method.
2. Description of Background Art
As a microwave plasma processing apparatus that introduces a microwave into a processing container to generate plasma of a processing gas, there are a reduced pressure plasma system of reducing pressure in a processing container to generate plasma, and an atmospheric pressure plasma system of generating plasma at atmospheric pressure.
For example, in a reduced pressure plasma system of JP-A No. 2009-224269, there is provided a plasma processing device in which the arrangement and number of multiple slots formed in a longitudinal direction of a waveguide tube are defined by the relationship between a free space wavelength λ and an intratubular wavelength λg and, at the same time, an impedance in the waveguide tube seen from a microwave electric source side is set to be approximately equal to an impedance in the waveguide tube when an electric source side is seen in a reverse direction. In JP-A No. 2009-224269 adopting a reduced pressure plasma system, in order to retain reduced pressure in a processing container, a dielectric plate intervenes between the waveguide tube and the processing container.
As the reduced pressure plasma system, in JP-A No. 2004-200390, there is proposed a plasma processing device in which a waveguide tube that transmits a microwave is inserted into a vacuum container. In JP-A No. 2004-200390, it is stated that, by providing a waveguide tube in the vacuum container, a dielectric member for retaining vacuum can be downsized and thinned, and a workpiece having a large area can be uniformly treated. The device of JP-A No. 2004-200390 has a double structure in which the waveguide tube is arranged in the vacuum container that requires air tightness.
And, in JP-A No. 2004-200390, a dielectric plate is not provided, but a gas introduction site is provided on a side wall of the processing container remote from the waveguide tube.
As yet another example of the reduced pressure plasma system, a plasma generation device that generates large-scale microwave line plasma is described in “Large-Scaled Line Plasma Production by Microwave in Narrowed Rectangular Waveguide,” 27th Plasma Processing Research Society (SPP-27) Proceedings Article P1-04 (Yasuhito Kimura et al.). In this plasma generation device, to reflect a microwave, a plunger whose position is adjustable is disposed on an end of a rectangular waveguide tube having a bottom on which one long slot is formed. This plasma generation device generates Ar plasma under a reduced pressure condition of around 667 Pa (5 Torr) in a stainless steel chamber which is vacuum-sealed with a glass plate.
On the other hand, as the atmospheric pressure plasma system, JP-A No. 2001-93871 proposes a plasma processing device having the following in the interior of a plasma generation portion: a slot antenna; a uniformity line connected to a slot forming surface of this slot antenna at a right angle to make a microwave uniform; and a slit provided on a tip side of this uniformity line to radiate a microwave. The plasma processing device of JP-A No. 2001-93871 is structured to treat a workpiece by plasma under atmospheric pressure by continuously supplying a process gas into a gap between the workpiece, which is formed on an outer side of the slit to generate plasma. This atmospheric pressure plasma processing device requires a slit of a waveguide tube and a slit of a uniformity line, and has a structure in which two each of waveguides and slots are provided.
Prior to this application, the present inventors have provided a plasma generation device in which a microwave is supplied into a long waveguide tube, multiple slot holes are formed on a wall of the waveguide tube corresponding to a position of an antinode of a standing wave of a microwave formed in a longitudinal direction in the waveguide tube, and high density atmospheric pressure plasma is generated in the interior of the slot holes (Japanese Patent Application No. 2010-207774).
The entire contents of these publications are incorporated herein by reference.
According to one aspect of the present invention, a plasma generation device has a microwave generation device which generates a microwave, a waveguide tube having a hollow interior space and connected to the microwave generation device such that the waveguide tube has a longitudinal direction in a transmission direction of the microwave and a rectangular cross section in a direction orthogonal to the transmission direction, a phase-shifting device which cyclically shifts a phase of a standing wave generated in the interior space of the waveguide tube by the microwave, and a gas supply device which is connected to the waveguide tube and supplies a processing gas into the interior space of the waveguide tube. The waveguide tube has an antenna portion having one or more slot holes which release plasma generated by the microwave to the outside of the waveguide tube, the slot hole is formed on a wall forming a short side or a long side of the antenna portion, and the waveguide tube plasmatizes the processing gas in the atmospheric pressure state supplied into the interior space of the waveguide tube by the microwave in the slot hole and releases the plasma to the outside from the slot hole.
According to another aspect of the present invention, a plasma processing apparatus has a support device which supports a workpiece, and a plasma generation device which generates plasma and releases the plasma toward the workpiece supported by the support device. The plasma generation device has a microwave generation device which generates a microwave, a waveguide tube having a hollow interior space and connected to the microwave generation device such that waveguide tube has a longitudinal direction in a transmission direction of the microwave and has a rectangular cross section in a direction orthogonal to the transmission direction, a phase-shifting device which cyclically shifts a phase of a standing wave generated in the interior space of the waveguide tube by the microwave, and a gas supply device which is connected to the waveguide tube and supplies a processing gas into the interior space of the waveguide tube, the waveguide tube has an antenna portion having one or more slot holes which release plasma generated by the microwave to the outside of the waveguide tube, the slot hole is formed on a wall forming a short side or a long side of the antenna portion, and the waveguide tube plasmatizes the processing gas in the atmospheric pressure state supplied into the interior space of the waveguide tube by the microwave in the slot hole and releases the plasma to the outside from the slot hole such that the plasma applies processing on the workpiece.
According to yet another aspect of the present invention, a plasma processing method includes generating plasma using a plasma generation device, and releasing the plasma generated by the plasma generation device from the plasma generation device such that the plasma applies processing on a workpiece. The plasma generation device has a microwave generation device which generates a microwave, a waveguide tube having a hollow interior space and connected to the microwave generation device such that waveguide tube has a longitudinal direction in a transmission direction of the microwave and has a rectangular cross section in a direction orthogonal to the transmission direction, a phase-shifting device which cyclically shifts a phase of a standing wave generated in the interior space of the waveguide tube by the microwave, and a gas supply device which is connected to the waveguide tube and supplies a processing gas into the interior space of the waveguide tube, the waveguide tube has an antenna portion having one or more slot holes which release plasma generated by the microwave to the outside of the waveguide tube, the slot hole is formed on a wall forming a short side or a long side of the antenna portion, and the waveguide tube plasmatizes the processing gas in the atmospheric pressure state supplied into the interior space of the waveguide tube by the microwave in the slot hole and releases the plasma to the outside from the slot hole such that the plasma applies processing on the workpiece.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
The embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings.
A processing container 10 is used for compartmenting a plasma processing space, and can be formed of, for example, a metal such as aluminum, stainless steel or the like. It is preferable that the interior of the processing container 10 has been subjected to, for example, surface processing that enhances resistance to plasma erosion, such as alumite processing. In the processing container 10, an opening is provided for loading/unloading the workpiece (S) (not shown). In addition, since the plasma processing apparatus 100 of the present embodiment is of an atmospheric pressure plasma system, it is not always necessary to provide the processing container 10, but is optional.
A plasma generation device 20 includes a microwave generation device 21 that generates a microwave; a rectangular waveguide tube 22 that is connected to the microwave generation device 21 and includes an antenna portion 40 as a part thereof; a gas supply device 23 that is connected to the rectangular waveguide tube 22 and supplies a processing gas into the interior thereof; an air exhausting device 24 for exhausting a gas in the antenna portion 40 and, optionally, the air in a processing container 10; a phase shifting device (25A) as a means of phase shifting, which cyclically shifts a phase of a standing wave in the rectangular waveguide tube 22 (particularly, in the antenna portion 40); and a partition 26 made of a dielectric such as quartz for blocking passage of a processing gas in the interior of the rectangular waveguide tube 22. Also, a slot hole 41 is formed on one wall surface of the rectangular waveguide tube 22. The region in which the slot hole 41 is formed works as an antenna portion 40 that releases plasma generated in the slot hole 41 toward a workpiece (S) on the outside.
A microwave generation device 21 generates a microwave of a frequency of, for example, 2.45 GHz to 100 GHz, preferably 2.45 GHz to 10 GHz. The microwave generation device 21 of the present embodiment has a pulse oscillation function and can generate a pulse-type microwave. An example of the structure of the microwave generation device 21 is shown in
This pulse control portion 37 receives commands from a controller 61 (described later) of a control portion 60, and outputs a control signal toward the pulse switch portion 36. And, by inputting a control signal into the pulse switch portion 36 while high voltage is supplied from electric source portion 31, a rectangular wave of predetermined voltage is supplied to the magnetron (or klystron) 33 of the oscillation portion 32, and a microwave pulse is output. A pulse of this microwave can be controlled at a pulse-on-time of 10 to 50 μsec, a pulse-off-time of 200 to 500 μsec, and a duty ratio of 5 to 70%, preferably 10 to 50%. In addition, in the present embodiment, the pulse oscillation function is provided to prevent heat accumulation at the antenna portion 40 that may cause a transition from low-temperature non-equilibrium discharge to arc discharge when continuously discharged. Therefore, when a cooling mechanism of the antenna portion 40 is separately provided, it is an option to provide such a pulse oscillation function.
Although omitted from showing in the drawings, a microwave generated in the microwave generation device 21 is transmitted to the antenna portion 40 set to be a part of the rectangular waveguide tube 22 via an isolator that controls the direction of a microwave and a matching device that performs impedance matching of a waveguide tube.
A rectangular waveguide tube 22 is long in a transmission direction of a microwave and, at the same time, is hollow in such a way that a cross section in a direction orthogonal to a transmission direction of a microwave is rectangular. The rectangular waveguide tube 22 is formed of, for example, a metal such as copper, aluminum, iron, stainless steel or the like, or an alloy thereof.
The rectangular waveguide tube 22 includes an antenna portion 40 as a part thereof. In the present embodiment, the antenna portion 40 has one slot hole 41 on a wall set to be a short side or on a wall set to be a long side in a cross section thereof. Namely, a region that is part of the rectangular waveguide tube 22 and in which the slot hole 41 is formed corresponds to the antenna portion 40. In
A gas supply device (GAS) 23 is connected to a gas introduction portion (22b) provided in a branch tube 22a that branches from the rectangular waveguide tube 22 between the antenna portion 40 and an end portion (22E) of the rectangular waveguide tube 22. The gas supply device 23 includes a gas supply source, a valve, a flow rate controlling device and the like, which are not shown. The gas supply source is provided for each type of processing gas. Examples of the processing gas include hydrogen, nitrogen, oxygen, a water steam, a flon (CF4) gas and the like. In the case of the flon (CF4) gas, it is necessary to provide an air exhausting device 24 as well. Also, for example, a supply source of an inactive gas such as argon, helium, a nitrogen gas or the like can be also provided. A processing gas supplied into the rectangular waveguide tube 22 from the gas supply device 23 is plasmatized by generation of discharge by a microwave in the slot hole 41.
An air exhausting device 24 includes a valve, a turbo-molecular pump, a dry pump and the like, which are not shown. The air exhausting device 24 is connected to a branch tube (22a) of the rectangular waveguide tube 22 and an exhaust port (10a) of a processing container 10, in order to exhaust the air in the rectangular waveguide tube 22 and the processing container 10. For example, when the process is ended, a processing gas remaining in the rectangular waveguide tube 22 is rapidly removed from the rectangular waveguide tube 22 by actuating the air exhausting device 24. Also, when discharge is initiated, the air exhausting device 24 is used to have a processing gas replaced effectively with a gas in the atmosphere of the rectangular waveguide tube 22 and processing container 10. In addition, in the plasma processing apparatus 100 of the present embodiment, which is an atmospheric pressure plasma processing apparatus, it is an option for the air exhausting device 24 to be provided. However, when a processing gas, particularly, a CF4 gas, which is stable at a normal temperature, produces a fluorine radical (F) or a fluorocarbon radical (CxFy) which is highly reactive when plasmatized, it is preferable for the air exhausting device 24 to be provided.
A phase shifting device (25A) of the present embodiment has a wall member that makes a linear motion, advancing into and retracting from the rectangular waveguide tube 22, in a direction crossing (preferably, a direction orthogonal to) a longitudinal direction of the rectangular waveguide tube 22. The phase shifting device (25A) causes the wall member to shuttle cyclically in a linear motion. Specifically, as shown in
As a material of the block 111, for example, a dielectric such as quartz, alumina and the like, or a metal such as aluminum, stainless steel and the like can be used. When the dielectric is used, it is preferable to use a dielectric material having a large specific dielectric constant ∈r and a small dielectric tangent (tan δ). In addition, a specific dielectric constant ∈r may be non-uniform in the block 111, and the block 111 can be formed of two or more dielectrics having different specific dielectric constants ∈r. The shape of the block 111 can be like that of a plate, or a prism or square tube, as shown in
When a block 111 is a dielectric, transmission, absorption and reflection of a microwave that propagates through the rectangular waveguide tube 22 are generated in the block 111. To what degree the transmission, absorption and reflection of a microwave are generated differs depending on the specific dielectric constant ∈r and loss coefficient (∈r×tan δ) of the material making up the block 111.
When the block 111 is made of a material having a small loss coefficient (e.g. quartz or high purity alumina), most of a microwave is transmitted through the block 111, and absorption and reflection are reduced relatively. In this case, since a wall surface (111a) of the block 111 is smaller than a cross section of the rectangular waveguide tube 22, a part of a microwave irradiated to the block 111 is propagated by transmitting through the block 111, and the remaining microwave is propagated by diffracting around the block 111. Also, a wavelength λd of a microwave transmitted in a dielectric becomes smaller than an intratubular wavelength λg [λd=λg/sqrt(∈r); herein, sqrt means a square root].
Due to such a difference in wavelengths, an associated wave after it has passed through the block 111 is refracted to a side of the block 111 that is a dielectric. By this refraction, a phase of a standing wave is shifted, and positions of an antinode and a node of a standing wave generated in the rectangular waveguide tube 22 are moved. And, in order to make a wavelength λd smaller than an intratubular wavelength λg, it is desirable to use a material having a large specific dielectric constant ∈r in the block 111.
When the block 111 is made of a material having a great loss coefficient, the amount of a microwave that is absorbed in the block 111 is increased, a dielectric becomes easily heated, and the power loss of a microwave that was output and supplied from the microwave generation device 21 increases. As a result, since the amount of a microwave that can be used for plasma discharge is reduced, this is not desirable. Therefore, as a material of the block 111, it is desirable to use a dielectric material having a large specific dielectric constant ∈r and a small loss coefficient (∈r×tan δ). Since a loss coefficient is a product of a specific dielectric constant ∈r and a dielectric tangent tan δ, for both a large specific dielectric constant ∈r and a small loss coefficient to be realized, the dielectric tangent tan δ needs to be small. That is, as a material of the block 111, it is desirable to use a dielectric material having a large specific dielectric constant ∈r and a small dielectric tangent tan δ.
When a block 111 is a metal, substantially the entire microwave that propagates through the rectangular waveguide tube 22 is reflected by a wall surface (111a) of the block 111. For this reason, as shown in
By contrast, when the block 111 has been extracted from a rectangular waveguide tube 22 (when the block 111 has been pulled up to an upper position as shown in
As described above, by shuttling the block 111 cyclically into and out of the rectangular waveguide tube 22, positions of an antinode and a node of a standing wave are moved on a predetermined cycle. Accordingly, line plasma is generated to be uniform by time average in a slot hole 41 in a longitudinal direction of an antenna portion 40. Therefore, the process on a workpiece is conducted homogeneously in a longitudinal direction of the antenna portion 40.
The block 111 has a wall surface (111a) that faces a microwave propagating through the rectangular waveguide tube 22. When an area of this wall surface (111a) is too small, transmission or reflection is hard to achieve, and when the area is too great, the material cost of the block 111 rises.
In order to prevent a microwave from leaking from an insertion opening (22c) to the outside, it is preferable for the phase shifting device (25A) to be covered with a cover member 84, as shown in
A position at which the phase shifting device (25A) is disposed is not particularly limited but is preferred to be a position in the vicinity of an end portion (22E) of the rectangular waveguide tube 22. Particularly, by setting a position of the wall surface (111a) of the block 111 of the phase shifting device (25A) at the position of an antinode of a standing wave that was originally generated in the rectangular waveguide tube 22, positions of an antinode and a node of a standing wave are easier to move. Herein, a node of a standing wave originally generated in the rectangular waveguide tube 22 corresponds to an inner wall surface of the end portion (22E) of the rectangular waveguide tube 22 that is a fixed end. Therefore, as shown in
When the amount of insertion of the block 111 inserted into the rectangular waveguide tube 22 (see symbol (d) of
A period of a shuttling motion, with a cycle being an action of the block 111 advancing into and retracting from the rectangular waveguide tube 22, is preferably 1/1000 to ½ of a plasma processing process time, from the viewpoint of the uniformity of a plasma processing process, throughput and simplification of a driving mechanism.
The phase shifting device (25A) is not limited to an aspect in which the block 111 is inserted from above the rectangular waveguide tube 22, but may be structured so that the block 111 is moved into and out of the rectangular waveguide tube 22 from the left or right of, or from below the rectangular waveguide tube 22. Namely, the phase shifting device (25A) can be arranged on any of the upper, lower, left and right outer wall surfaces of the rectangular waveguide tube 22.
In the present embodiment, the plasma generation device 20 includes a partition 26 that blocks passage of a processing gas in the rectangular waveguide tube 22 between the microwave generation device 21 and the antenna portion 40. The partition 26 is made of a dielectric, for example, quartz or polytetrafluoroethylene such as Teflon (registered trademark), and prevents a processing gas in the rectangular waveguide tube 22 from flowing toward the microwave generation device 21, while passing a microwave.
A stage 50 supports a workpiece (S) positioned horizontal in a processing container 10. The stage 50 is provided to be supported by a supporting portion 51 disposed on a bottom of the processing container 10. Materials for the stage 50 and the supporting portion 51 are, for example, ceramics such as quartz, AlN, Al2O3 and BN, and metals such as Al and stainless steel. If necessary, a heater (not shown) may be embedded so that the workpiece (S) can be heated to around 250° C. In addition, in the plasma processing apparatus 100 of the present embodiment, the stage 50 is not limited specifically, and is selected based on the type of workpiece (S).
The plasma processing apparatus 100 can be applied on a workpiece (S) such as, for example, an FPD (flat panel display) substrate, a type of which is a glass substrate for LCD (liquid crystal indication display); a film member such as a polycrystalline silicon film; and a polyimide film adhered to the FPD substrate. Also, the plasma processing apparatus 100 can be used on a workpiece (S) such as, for example, a film member such as a polyethylene naphthalate (PEN) film, or a polyethylene terephthalate (PET) film, to perform surface cleaning processing or surface processing thereof so that an active element and a passive element such as an organic semiconductor are formed. Further, the plasma processing apparatus 100 can be used to perform, for example, modification processing of a thin film provided on an FPD substrate as the workpiece (S), or surface processing, cleaning processing and modification processing on the film member used as the workpiece (S) to improve adhesiveness to an FPD substrate. In the plasma processing apparatus 100 having the phase shifting device (25A), since high density line plasma is uniformly formed over the entire region of a long antenna portion 40, processing on the workpiece (S) having a relatively large area is performed effectively and homogeneously.
Each portion of the plasma processing apparatus 100 is structured to be controlled by being connected to a control portion 60. As shown in
Next, the arrangement and shape of a slot hole 41 in an antenna portion 40 are described using specific examples, referring to
When the length of a short side of a cross section of the antenna portion 40 is set as (L1) and the length of a long side as (L2) (that is, L1<L2), the slot hole 41 may be formed on any portion of the wall (40a) forming a short side, and the wall (40b) forming a long side, in a cross section of the antenna portion 40, but it is preferable for the slot hole 41 to be disposed on the wall (40a) forming a short side and having the length of (L1), as shown in
As shown in
In
The slot holes 41 may be disposed in one row or in multiple rows. An example in which multiple slot holes 41 are disposed in two rows is shown in
To obtain strong plasma, it is preferred for the rectangular slot hole 41 to be provided at a portion of an antinode of a standing wave generated in the rectangular waveguide tube 22 when the slot hole 41 is formed on the wall (40b) as a long side of the rectangular waveguide tube 22. In such a case, the electromagnetic field reaches its maximum value at a portion of an antinode of a standing wave, a surface current flowing on the wall (40b) that forms a long side flows in a direction from a portion of an antinode of a standing wave toward the wall (40a) that forms a short side of the rectangular waveguide tube 22, and the surface current increases as it comes closer to the wall 40a. Therefore, when the rectangular slot hole 41 is formed to be shifted toward a portion near the wall 40a that forms a short side of the rectangular waveguide tube 22 (side near a corner) rather than near the center of a wall surface of the wall (40b) that forms a long side, strong plasma is formed in the slot hole 41. For example, in
When two or more rows of slot holes 41 are disposed next to each other as shown in
In examples of
In each construction example of the above slot hole 41, it is preferable for an edge face 40c of an opening of the slot hole 41 to be provided obliquely so that an opening is widened from an inner side to an outer side of the rectangular waveguide tube 22 in a direction of the thickness of the wall (40a) (or wall 40b), as shown by enlargement in
A specific shape and an arrangement example of the slot hole 41 are not limited to the above examples. When a waveguide antenna is used, since a standing wave of a microwave formed in the rectangular waveguide tube 22 is utilized upon introduction of a microwave into the rectangular waveguide tube 22, it is advantageous for generating strong plasma if the slot hole 41 is provided at a portion of an antinode of a standing wave. If the slot hole 41 is provided at a portion of a node of a standing wave, the electromagnetic field is weak and plasma is not effectively generated in the slot hole 41. This is because plasma is not produced, or only weak plasma is produced, at a portion of a node of a standing wave formed in the rectangular waveguide tube 22. Therefore, in the plasma generation device 100 of the present embodiment, the phase shifting device (25A) is provided, a phase of a standing wave is made to be shifted, and positions of an antinode and a node of a standing wave are caused to be cyclically moved relative to the slot hole 41, in a longitudinal direction of the rectangular waveguide tube 22. From such a viewpoint, the slot hole 41 is preferred to be shaped so that, even when a position of an antinode of a standing wave is moved, the slot hole 41 is always present at a position of an antinode. It is most preferable for a long single slot hole 41 to be formed over the entire length of the antenna portion 40 as shown in
In the plasma generation device 100, as shown in
Next, the operation of the plasma processing apparatus 100 is described. First, a workpiece (S) is loaded into a processing container 10 and is placed on a stage 50. Then, a processing gas is introduced into the rectangular waveguide tube 22 from a gas supply device 23 at a predetermined flow rate via a gas introduction portion 22b and a branch tube 22a. By introducing the processing gas into the rectangular waveguide tube 22, pressure in the rectangular waveguide tube 22 becomes greater relative to the outside atmospheric pressure.
Then, the power of the microwave generation device 21 is turned on to generate a microwave. Thereupon, a pulse-type microwave may be generated. A microwave is introduced into the rectangular waveguide tube 22 via a matching circuit, which is not shown. By the introduced microwave, an electromagnetic field is formed in the rectangular waveguide tube 22, and the processing gas supplied into the rectangular waveguide tube 22 is plasmatized in the slot hole 41 of the antenna portion 40. This plasma is radiated through the slot hole 41 toward a workpiece (S) on the outside from the interior of the antenna portion 40 of the rectangular waveguide tube 22, which has relatively high pressure. While a microwave is supplied into the rectangular waveguide tube 22, a driving portion 112 of the phase shifting device (25A) is driven to move a block 111 back and forth, repeatedly advancing into and retracting from the rectangular waveguide tube 22. Thus, a phase of a standing wave in the antenna portion 40 is changed, positions of an antinode and a node are changed cyclically, and line plasma is formed to be uniform by time average in a longitudinal direction of the antenna portion 40.
As described, since the plasma generation device 20 and the plasma processing apparatus 100 provided therewith of the present embodiment have the phase shifting device (25A), positions of an antinode and a node of a standing wave are changed cyclically so that line plasma is generated to be uniform by time average in a longitudinal direction of the antenna portion 40. Accordingly, the process on a workpiece is conducted homogeneously in a longitudinal direction of the antenna portion 40.
Since the plasma processing apparatus 100 is an atmospheric pressure plasma device requiring no vacuum container, a dielectric plate does not need to be provided between the rectangular waveguide tube 22 and the workpiece (S), and loss due to absorption of a microwave with the dielectric plate is prevented. And, since the plasma processing apparatus 100 is an atmospheric pressure plasma device, a pressure-resistant vacuum container and a sealing mechanism are unnecessary, and the device may have simple construction. Further, in the plasma generation device 20 and the plasma processing apparatus 100 provided therewith of the present embodiment, since a processing gas supplied into the rectangular waveguide tube 22 is plasmatized by a microwave in the slot hole 41 and is released to the outside from the slot hole 41, special gas introduction equipment such as a shower head is not necessary, and the size of the device can be reduced. That is, since the rectangular waveguide tube 22 plays the role of shower head, gas introduction equipment such as the shower head and a shower ring does not need to be separately provided, and device structure is simplified.
Next, a plasma processing apparatus of a second embodiment of the present invention is described, referring to
The plasma processing apparatus 101 of the present embodiment (
The phase shifting device (25B) of the present embodiment has a wall member that performs rotational motions around an axis set in a direction corresponding to a longitudinal direction of the rectangular waveguide tube 22. Specifically, as shown in
The rotor 121 has a wall surface 121a that faces a microwave propagating through the rectangular waveguide tube 22. The shape of the rotor 121 is shown in
The rotor 121 can have a shape that is non-uniform in a rotational direction and, for example, as shown in
Concerning the rotor 121, it is thought that, when an accumulated area of insertion into the rectangular waveguide tube 22 (herein, a time-integrated area of a wall surface 121a, first and second wall surfaces 121A and 121B which are inserted into the rectangular waveguide tube 22) is too small, transmission and reflection become difficult to achieve, and when the area is too great, in the case where the actual insertion amount deviates from a set insertion amount and increases, the rotor 121 is damaged by being contacted and rubbed by the inner surface of the rectangular waveguide tube 22.
It is preferable for a period of rotational motion, one cycle being an action of rotating the rotor 121 one time, to be 1/1000 to ½ of a plasma processing process time, from the viewpoint of uniformity of a plasma processing process, throughput and simplification of a driving mechanism.
As described, the phase shifting device (25B) operates the driving portion 122 to rotate the rotor 121 around an axis set in a direction corresponding to a longitudinal direction of the rectangular waveguide tube 22, and cyclically inserts and retracts one or multiple portions of rotor 121 into and out of the rectangular waveguide tube 22. By so doing, the phase shifting device (25B) cyclically shifts a phase of a standing wave in a longitudinal direction of the rectangular waveguide tube 22. Namely, when the rotor 121 has a shape that is non-uniform in a rotational direction as shown in
In
In the present modified example, as the rotor 121, a rotor 121 whose thickness is non-uniform in a rotational axis direction as shown in
As a result, a phase of a standing wave generated in the rectangular waveguide tube 22 is cyclically changed.
In the phase shifting device (25C) of the present modified example, as shown in
In the second embodiment, the rotor 121 is not limited to those shown in
In the present embodiment, a material of the rotor 121 and positions on which the phase shifting devices 25B and 25C are disposed may be the same as those of the first embodiment. Also, in order to prevent a microwave from leaking to the outside through an insertion opening (22c), it is preferable to cover the phase shifting devices (25B, 25C) with a cover member 84, as in the first embodiment. The rest of the structure and its effect according to the present embodiment are the same as those of the first embodiment.
Next, a plasma processing apparatus of a third embodiment of the present invention will be explained, referring to
The plasma processing apparatus 102 of the present embodiment (
The phase shifting device (25D) of the present embodiment has a wall member that performs rotational motions around an axis set in a direction crossing (preferably, a direction orthogonal to) a longitudinal direction of the rectangular waveguide tube 22. Specifically, as shown in
The rotor 131 has a wall surface (131a) that cyclically faces a microwave propagating through the rectangular waveguide tube 22. In addition, both sides of a plate-like rotor 131 may be utilized as the wall surface (131a) that cyclically faces a microwave. The shape of the rotor 131 is not particularly limited, but for example, as shown in
That is, since at such an angle that the wall surface (131a) of the rotor 131 is orthogonal to a longitudinal direction of the rectangular waveguide tube 22 (i.e. progression direction of microwave), transmission and/or reflection of a microwave are generated by the rotor 131, a phase of a standing wave generated in the rectangular waveguide tube 22 is shifted, and positions of an antinode and a node are moved. On the other hand, since at such an angle that the wall surface (131a) of the rotor 131 becomes parallel to a longitudinal direction of the rectangular waveguide tube 22, the thickness of the rotor 131 is small, transmission and reflection of a microwave are reduced to an approximately negligible level, a phase of a standing wave is returned to its original state where a reflected wave is generated at an end portion (22E) of the rectangular waveguide tube 22, and positions of an antinode and a node are also recovered. Therefore, by rotating the rotor 131 in the rectangular waveguide tube 22, a phase of a standing wave is cyclically shifted, positions of an antinode and a node are cyclically moved, and line plasma is generated to be uniform by time average in a longitudinal direction of the antenna portion 40. As a result, the process on a workpiece is conducted homogeneously in a longitudinal direction of the antenna portion 40.
In the present embodiment, the shape of the rotor 131 is not limited to those shown in
When an area of the wall surface (131a) that faces a microwave propagating through the rectangular waveguide tube 22 is too small, transmission and reflection are difficult to achieve, and when the area is too large, problems such as displacement or damage may arise.
It is preferable for a period of rotational movement, one cycle being the action of a 360° rotation of a rotor 131 in the rectangular waveguide tube 22, to be 1/1000 to ½ of a plasma processing process time, from the viewpoint of the uniformity of a plasma processing process, throughput, and simplification of a driving mechanism.
In the present embodiment, a material of the rotor 131 and the disposition position of the phase shifting device (25D) can be the same as those of the first embodiment. Since the rotational axis of the rotor 131 may be positioned in any direction as long as it crosses a longitudinal direction of the rectangular waveguide tube 22, for example, a rotational axis of the rotor 131 may be provided in a direction vertical or horizontal to the rectangular waveguide tube 22 that is set long in a horizontal direction. Also, in order to prevent a microwave from leaking to the outside through an insertion opening (22c), it is preferable for the phase shifting device (25D) to be covered with a cover member 84, as in the first embodiment. The rest of the structure and its effect according to the present embodiment are the same as those of the first embodiment.
Next, a plasma processing apparatus of a fourth embodiment of the present invention will be explained, referring to
The plasma processing apparatus 103 of the present embodiment (
A phase shifting device (25E) of the present embodiment has a wall member that faces a microwave propagating through the rectangular waveguide tube 22. This wall member is provided at an end portion of the rectangular waveguide tube 22 and moves back and forth, advancing into and retracting from the rectangular waveguide tube 22 in a longitudinal direction. Specifically, as shown in an enlarged view in
The driving portion 142 cyclically shuttles the movable body 141 back and forth in a linear line in a longitudinal direction of the rectangular waveguide tube 22. The driving portion 142 causes the shaft 143 and the movable body 141 to advance into and retract from the rectangular waveguide tube 22 along a predetermined distance L5, via an insertion opening 22d provided at an end portion (22E) of the rectangular waveguide tube 22. When retracted, a most of the movable body 141 is moved to the outside of the rectangular waveguide tube 22 through the insertion opening 22d, and retracts until the wall surface (141a) reflecting a microwave aligns with an inner wall surface of the end portion (22E) of the rectangular waveguide tube 22. The driving portion 142 may be formed with, for example, an air cylinder, an oil hydraulic cylinder or the like, or may be formed by combining a driving source such as a motor or the like with a crank mechanism, a Scotch yoke mechanism, a rack and pinion mechanism or the like. In this way, the phase shifting device (25E) shuttles the movable body 141 back and forth in a linear line in a longitudinal direction of the rectangular waveguide tube 22 by actuating the driving portion 142 so that the wall surface (141a) to reflect a microwave is moved. Thus, a phase of a standing wave generated in the rectangular waveguide tube 22 is shifted cyclically.
Namely, when the movable body 141 has advanced into the rectangular waveguide tube 22, since a microwave is reflected by the wall surface (141a) of the movable body 141 which has advanced a distance L5, the waveguide length of the rectangular waveguide tube 22 is substantially shortened. Accordingly, positions of an antinode and a node of a standing wave generated in the rectangular waveguide tube 22 are moved. On the other hand, in a state where the wall surface (141a) of the movable body 141 has retracted to the original end portion (22E) of the rectangular waveguide tube 22, the waveguide length becomes the original length, and positions of an antinode and a node of a standing wave are recovered as before. Therefore, by repeating an action of advancing and retracting the movable body 141 into and out of the rectangular waveguide tube 22, positions of an antinode and a node of a standing wave are moved cyclically, and line plasma is generated to be uniform by time average in a longitudinal direction of the antenna portion 40. As a result, the process on a workpiece is conducted homogeneously in a longitudinal direction of the antenna portion 40.
The above non-patent publication describes a plasma generation device in which a movable plunger is provided at an end portion of a rectangular waveguide tube. However, since the device of Non-Patent Reference 1 is not an atmospheric pressure plasma device, it is greatly different technically from the present invention. Also, in order to study a waveguide length that can generate stable plasma, the plunger of Non-Patent Reference 1 was devised merely to simplify changing a position of a fixed end of a rectangular waveguide tube. Therefore, unlike the plasma processing apparatus 103 of the present embodiment, the device described in Non-Patent Reference 1 does not have the function of moving a reflection position of a microwave cyclically while plasma is generated so as to change a phase of a standing wave and to generate line plasma to be uniform by time average.
In the present embodiment, the movable body 141 is not limited to the shape shown in
A distance (L5) by which the movable body 141 of the phase shifting device (25E) advances is not limited specifically. However, by setting a position of the wall surface (141a) at a position of an antinode of a standing wave originally generated in a rectangular waveguide tube 22 when the movable body 141 has been advanced, it is easier to move positions of an antinode and a node of a standing wave. Here, since a node of the original standing wave generated in the rectangular waveguide tube 22 corresponds to an inner wall surface of an end portion (22E) of the rectangular waveguide tube 22 that is a fixed end, it is preferable for the length (L5) by which the movable body 141 is advanced to be set to be n×λg/4 relative to the intratubular wavelength λg of a standing wave (here, “n” means a positive odd integer, preferably 1), between an end portion (40E) of the antenna portion 40 and an end portion (22E) of the rectangular waveguide tube 22.
When one cycle is set for advancing and retracting the movable body 141 into and out of the rectangular waveguide tube 22, it is preferable for a period of shuttling movable body 141 back and forth in a linear line to be 1/1000 to ½ of a plasma processing processing time, in view of the uniformity of a plasma processing process, throughput, and simplification of a driving mechanism.
To prevent a microwave from leaking to the outside through an insertion opening (22d), it is also preferable in the present embodiment to cover the phase shifting device (25E) with a cover member 84. The rest of the structure and its effect according to the present embodiment are the same as those of the first embodiment.
In the following, a plasma processing apparatus of a fifth embodiment of the present invention is described by referring to
The plasma processing apparatus 104 of the present embodiment (
In the present embodiment, one pair of phase shifters (151A, 151B), which are a phase shifting means, sandwich the antenna portion 40 therebetween and are provided on both sides thereof. Namely, the phase shifter (151A) is disposed farther on an end portion (22E) side of the rectangular waveguide tube 22 than the antenna portion 40, and the phase shifter (151B) is disposed farther on a microwave generation device 21 side of the rectangular waveguide tube 22 than the antenna portion 40. Phase shifters (151A, 151B) are respectively connected to the rectangular waveguide tube 22 and form a part of the waveguide.
Both of the phase shifters (151A, 151B) have the same structure. An example of the structure of the phase shifter (151A) is schematically shown in
Math 1
As described above, by using the phase shifter (151A), electric power transmission from the port 1 to the port 4 is conducted without loss. Alternatively, when a connecting portion between the rectangular waveguide tube 22 on an end portion (22E) side of the rectangular waveguide tube 22 is set as an incoming port, and a connecting portion between the rectangular waveguide tube 22 on a microwave generation device 21 side is set as an exiting port, electric power transmission is also conducted without loss. In addition, this is also true of the phase shifter (151B).
Two variable short-circuiting bars (155, 155) are structured to advance into or retract from the waveguide synchronously by a driving portion such as a motor or the like, which is not shown. By advancing and retracting the variable short-circuiting bar 155, a phase of a microwave can be regulated variably. By repeatedly advancing and retracting two each variable short-circuiting bars (155, 155) in the phase shifter (151A) or (151B), positions of an antinode and a node of a standing wave are moved cyclically, and line plasma is generated to be uniform by time average in a longitudinal direction of the antenna portion 40. As a result, the process on a workpiece is conducted homogeneously in a longitudinal direction of the antenna portion 40. Also, in the plasma processing apparatus 104 of the present embodiment, phase shifters (151A, 151B) are actuated in a reverse phase. Herein, “actuated in a reverse phase” means that phase shifters (151A, 151B) are actuated so that a shift in a phase generated by the phase shifter (151A) is canceled by the phase shifter (151B).
In the present embodiment, driving the variable short-circuiting bar 155 of the phase shifter (151A) and driving the variable short-circuiting bar 155 of the phase shifter (151B) are controlled simultaneously so that they are actuated in a reverse phase, and a shift in a phase generated by the phase shifter (151A) is canceled by the phase shifter (151B). Namely, while positions of an antinode and a node of a standing wave in the antenna portion 40 are moved cyclically by the phase shifter (151A), a shift in a phase of a reflected wave that propagates toward the microwave generation device 21 side is corrected by the phase shifter (151B). When a phase of a standing wave in the rectangular waveguide tube 22 is changed only by the phase shifter (151A), complex impedance matching needs to be conducted on the microwave generation device 21 side, due to a reflected wave having a changed phase. However, if the phase shifter (151B) is provided in addition to the phase shifter (151A) and these two are actuated in a reverse phase, the phase shifters (151A, 151B) appear as if they were not present when seen from the microwave generation device 21 side. Thus, impedance matching is simplified. As described, in the present embodiment, two phase shifters (151A) and (151B) are actuated in a reverse phase, while positions of an antinode and a node of a standing wave are moved cyclically, thus reducing the load on an electric source portion 31 (see
The rest of the structure and its effect according to the present embodiment are the same as those of the first embodiment.
In plasma processing apparatus (100, 101, 102, 103 and 104) of the first to fifth embodiments, a temperature regulating device can be provided in the rectangular waveguide tube 22 in plasma generation devices (20, 20A, 20B, 20C and 20D) respectively. Specific examples in which the temperature regulating device is provided in the rectangular waveguide tube 22 are shown in
In the present embodiment, the temperature regulating device 161 may be structured in such a way that a heat medium for cooling or heating, for example, is supplied to circulate in the interior, or may be structured with a heater by resistance heating or the like. Since the temperature of the rectangular waveguide tube 22 including the antenna portion 40 can be regulated by the temperature regulating device 161, relative to changes in the temperature of the rectangular waveguide tube 22 (particularly, antenna portion 40) caused by plasma discharge, safety and reproducibility of plasma discharge can be enhanced.
The rest of the structure and its effect according to the present embodiment are the same as those of the first to fifth embodiments.
Using plasma generation devices (20, 20A, 20B, 20C and 20D) of the first to fifth embodiments, it is an option to form a plasma processing apparatus 105 in which multiple (3 in
As shown in
The rest of the structure and its effect according to the present embodiment are the same as those of the first to sixth embodiments.
Next, the test results confirming the effect of the present invention are described. Using a plasma processing apparatus having the same structure as that shown in
As shown in
Only the insertion depth (d) of the block 111 was changed by the following setting of parameters, and the shift amount [mm] of a phase was calculated.
Regarding the rectangular waveguide tube 22, Ly: 800 mm, Lx: 108 mm, Lz: 56 mm, r: 690 mm, intratubular wavelength λg: 148 mm.
Regarding the block 111, specific dielectric constant ∈r 10, ly: 36 mm, lx: 36 mm, and the insertion depth (d) of the block 111 was set to be: 0 mm (no insertion), 5 mm, 10 mm, 20 mm, 25 mm, 28 mm, 30 mm, 40 mm, 45 mm, 48 mm or 50 mm.
The results of the simulation are shown in
Next, the influence of the width of the block 111 (length of a side parallel to a width direction of the rectangular waveguide tube 22) (lx) on a shift of a phase of a standing wave was simulated. Herein, a simulation was conducted under the same conditions as those described above, except that the insertion depth (d) of the block 111 was set to be 28 mm, the distance (r) from an initiation point of a waveguide to an insertion position of the block 111 was set to be 20 mm, and the (lx) was changed as follows.
lx: 0 mm (no insertion), 5 mm, 10 mm, 20 mm, 30 mm, 36 mm, 40 mm, 50 mm, 72 mm, or 108 mm
The results of the simulation are shown in
From the results of the simulation, it was confirmed that, by inserting the block 111 into the rectangular waveguide tube 22, a phase of a standing wave in the rectangular waveguide tube 22 is changed. In addition, it was also confirmed that the amount of change of a phase can be regulated by the width (lx) and the insertion depth (d) of the block 111 to be inserted into the rectangular waveguide tube 22.
So far, embodiments of the present invention have been described in detail to show the modes to carry out the present invention. However, the present invention is not limited to the embodiments above. A person skilled in the art can conduct many modifications without deviating from the concept and the scope of the present invention, and those are also included in the scope of the present invention. For example, in the above embodiments, as the workpiece (S), an FPD substrate and a film to be applied to the substrate were shown, but a processing subject was not specifically limited; for example, the present invention can be also applied to a substrate of a semiconductor wafer or the like.
The plasma generation device of one embodiment of the present invention is a plasma generation device of an atmospheric pressure system that generates uniform line plasma using a long waveguide tube and performs uniform processing on the workpiece.
By providing a means that can change a phase of a standing wave generated in a long waveguide tube, high density line plasma is generated uniformly in a longitudinal direction of the waveguide tube.
A plasma generation device according to an embodiment of the present invention includes a microwave generation device that generates a microwave; a hollow waveguide tube that is connected to the microwave generation device and is shaped long in a transmission direction of the microwave while a cross section in a direction orthogonal to the transmission direction is shaped rectangular; a gas supply device that is connected to the waveguide tube and supplies a processing gas into the interior thereof; an antenna portion that is a part of the waveguide tube and releases plasma generated by the microwave to the outside; one or multiple slot holes formed on a wall that forms a short side or a long side of the antenna portion; and a phase shifting means that cyclically shifts a phase of a standing wave by the microwave generated inside the waveguide tube. The plasma generation device plasmatizes the processing gas supplied into the waveguide tube in the atmospheric pressure state by the microwave in the slot hole, and releases the plasma to the outside from the slot hole. Also, the plasma generation device may be such that the phase shifting means has a wall member that transmits and/or reflects a microwave propagating through the waveguide tube, and cyclically changes positions of an antinode and a node of the standing wave by the wall member.
The wall member may move back and forth in a linear line, advancing into or retracting from the waveguide tube in a direction that crosses a longitudinal direction of the waveguide tube.
The wall member may perform rotational movements around an axis set in a direction corresponding to a longitudinal direction of the waveguide tube. In this case, rotational movements of the wall member may be eccentric rotations, the wall member may have a shape that is non-uniform in a rotational direction, or the wave member may have a non-uniform thickness in a longitudinal direction of the waveguide tube.
The wall member may perform rotational movements around an axis set in a direction that crosses a longitudinal direction of the waveguide tube.
The wall member may be provided at an end portion of the waveguide tube, and may move back and forth in a linear line, advancing into or retracting from the waveguide tube in a longitudinal direction of the waveguide tube.
The material of the wall member may be made of a dielectric or a metal.
The plasma generation device may further include a cover member that covers the phase shifting means.
The phase shifting means may be one pair of phase shifters that are structured to sandwich the antenna portion therebetween and are connected to the rectangular waveguide tube on both sides thereof, and the one pair of phase shifters may be actuated in a reverse phase from each other.
The slot hole may be shaped to be rectangular, and may be provided so that its longitudinal direction corresponds to a longitudinal direction of the antenna portion. In this case, only one long slot hole may be provided in the antenna portion, multiple slot holes may be disposed in one row in the antenna portion, or multiple slot holes may be arranged parallel in multiple rows in the antenna portion.
The plasma generation device may include a partition that blocks passage of the processing gas in the waveguide tube between the microwave generation device and the antenna portion.
An edge face of the slot hole may be provided obliquely so that the opening width varies in a direction of the thickness of the wall.
Furthermore, the plasma generation device may include a pulse generator, and may generate plasma by generating a pulse-type microwave.
A plasma processing apparatus according to another embodiment of the present invention includes the plasma generation device and performs predetermined processing on a workpiece using generated plasma. While cyclically shifting a phase of the standing wave by the phase shifting means, the plasma processing apparatus plasmatizes the processing gas supplied into the waveguide tube in an atmospheric pressure state by the microwave in the slot hole, and releases the plasma to the outside from the slot hole to treat a workpiece. In this case, the antenna portion may be arranged so that the slot hole faces the workpiece. Alternatively, the antenna portion may be arranged on both upper and lower surfaces of the workpiece. Moreover, the workpiece may be film-like, and may be conveyed by a roll-to-roll system.
A plasma treating method according to a further embodiment of the present invention is a method of treating a workpiece using the plasma treating device. This plasma treating method plasmatizes the processing gas supplied into the waveguide tube in an atmospheric pressure state by the microwave through the slot hole, while cyclically shifting a phase of the standing wave by the phase shifting means, and releases the plasma to the outside from the slot hole to treat the workpiece.
Since the plasma generation device and the plasma processing apparatus include a phase shifting means that cyclically shifts a phase of a standing wave generated in the waveguide tube, positions of an antinode and a node of a standing wave can be moved during a certain time period. As a result, although those devices are of an atmospheric pressure plasma system by which it is hard to generate uniform plasma, line plasma is generated to be uniform by time average in a longitudinal direction of the waveguide tube. Therefore, homogeneous processing can be performed on a large workpiece in a longitudinal direction of the waveguide tube.
Since the plasma generation device and the plasma treating device are an atmospheric pressure plasma device requiring no vacuum container, it is not necessary to provide a dielectric plate between a waveguide tube and a workpiece, and loss due to absorption of a microwave by the dielectric plate is prevented. Also, since a processing gas supplied into the waveguide tube is plasmatized with a microwave and is released to the outside from a slot hole, high-density plasma is generated effectively. In addiiton, dedicated gas introduction equipment is not required, and the size of the device can be reduced. Therefore, by performing plasma processing on a workpiece using the plasma generation device and the plasma treating device, homogeneous processing is performed with high-density plasma while energy loss is suppressed as much as possible.
Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-052941 | Mar 2011 | JP | national |
| 2012-028187 | Feb 2012 | JP | national |
The present application is a continuation of PCT/JP2012/055331, filed Mar. 2, 2012, which is based upon and claims the benefit of priority to Japanese Application Nos. 2011-052941, filed Mar. 10, 2011, and 2012-028187, filed Feb. 13, 2012. The entire contents of these applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2012/055331 | Mar 2012 | US |
| Child | 14023006 | US |
