Patent Application
20150206778
This application claims the benefit of Japanese Patent Application No. 2014-007408, filed on Jan. 20, 2014, in the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference.
The present disclosure relates to a microwave processing apparatus and method for heating a substrate by introducing microwaves into a processing container.
Microwaves can be used to anneal a substrate such as a semiconductor wafer. Annealing using microwaves has a significant process advantage in that it allows for internal heating, local heating, and selective heating, compared with annealing devices using lamp heating or resistance heating. In order to uniformly heat a substrate using microwaves, it is important to effectively introduce microwaves into a processing container and evenly irradiate the microwaves to the substrate. For example, one type of microwave heat treatment device includes a concave lens for dispersing microwave output from a wave guide. The concave lens is aligned with a central line perpendicular to a main surface of a wafer.
When using a microwave processing apparatus for heat treatment, it is required to maintain a uniform heating temperature within a surface of a substrate. In order to increase uniformity of a heating temperature within a surface of a substrate, it is effective to finely adjust distribution of introduced microwaves within a processing container.
Some embodiments of the present disclosure provide a microwave processing apparatus capable of finely adjusting distribution of microwave within a processing container of the microwave processing apparatus.
According to an aspect of the present disclosure, there is provided a microwave processing apparatus for processing a substrate by irradiating a microwave to the substrate, including: a processing container configured to accommodate a substrate; and a microwave introducing device configured to have a microwave source that generates a microwave and introduce the microwave into a microwave radiation space within the processing container. The microwave introducing device includes: a waveguide configured to form a transmission path to guide the microwave into the processing container; a first microwave transmission window interposed between the transmission path and the microwave radiation space; and a second microwave transmission window installed to be closer to the microwave source than the first microwave transmission window, and configured to change a traveling direction of the microwave.
According to another aspect of the present disclosure, there is provided a microwave processing method for processing a substrate using the aforementioned microwave processing apparatus.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.
Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, systems, and components have not been described in detail so as not to unnecessarily obscure aspects of the various embodiments.
First, a microwave processing apparatus according to a first embodiment of the present disclosure will be described with reference to
The microwave processing apparatus 1 includes a processing container 2 for accommodating the wafer W to be processed, a microwave introducing device 3 for introducing microwaves into the processing container 2, a support device 4 for supporting the wafer W within the processing container 2, a gas supply mechanism 5 for supplying a gas into the processing container 2, an exhaust device 6 for vacuum-exhausting the interior of the processing container 2, and a controller 8 for controlling each component of the microwave processing apparatus 1.
The processing container 2 is formed of metal. As a material used to form the processing container 2, for example, aluminum, an aluminum alloy, stainless steel, or the like is used. The microwave introducing device 3 is installed above the processing container 2 and serves as a microwave introducing means for introducing microwaves into the processing container 2. A configuration of the microwave introducing device 3 will be described further down below in detail.
The processing container 2 includes a ceiling part 11 having a plate shape as an upper wall, a bottom part 13 as a lower wall, and four side wall parts 12 as side walls that connect the ceiling part 11 and the bottom part 13. Also, the processing container 2 has a plurality of microwave introducing ports 10 formed to penetrate through the ceiling part 11 vertically, a loading/unloading port 12a formed in one of the side wall parts 12, and an exhaust port 13a formed in the bottom part 13. Here, the four side wall parts 12 form a rectangular cylinder whose horizontal cross-section has right-angled connections. Thus, the processing container 2 has a hollow cubic shape. Also, inner surfaces of all the side wall parts 12 are flat and serve as reflective surfaces for reflecting microwaves. The loading/unloading port 12a serves to allow the wafer W to be loaded from and unloaded to a transfer chamber (not shown) adjacent to the processing container 2 therethrough. A gate valve GV is installed between the processing chamber 2 and the transfer chamber (not shown). The gate valve GV serves to open and close the loading/unloading port 12a. The gate valve GV airtightly seals the processing container 2 in a closed state, and allows for transfer of the wafer W between the processing container 2 and the transfer chamber (not shown) in an open state.
The support device 4 includes a tubular shaft 14 penetrating through a substantially central portion of the bottom part 13 of the processing container 2 and extending to the outside of the processing container 2, a plurality of (e.g., three) arm units 15 installed in a substantially horizontal direction from the vicinity of an upper end of the shaft 14, a plurality of support pins 16 detachably installed in each of the arm units 15, a rotary driving unit 17 that rotates the shaft 14, a lift driving unit 18 that moves the shaft 14 up and down, and a movable connecting unit 19 supporting the shaft 14 while connecting the rotary driving unit 17 and the lift driving unit 18. The rotary driving unit 17, the lift driving unit 18, and the movable connecting unit 19 are installed outside of the processing container 2. When the interior of the processing container 2 is made to be in a vacuum, a seal mechanism 20 such as a bellows may be also installed around the portion where the shaft 14 penetrates through the bottom part 13.
In the support device 4, the shaft 14, the arm units 15, the rotary driving unit 17, and the movable connecting unit 19 form a rotary mechanism for horizontally rotating the wafer W supported by the support pin 16. Also, in the support device 4, the shaft 14, the arm units 15, the lift driving unit 18, and the movable connecting unit 19 form a level position adjusting mechanism for adjusting a level position of the wafer W supported by the support pins 16. The plurality of support pins 16 makes contact with a rear surface of the wafer W within the processing container 2 to support the wafer W. The plurality of support pins 16 is installed such that upper end portions thereof are arranged along a circumferential direction of the wafer W. By driving the rotary driving unit 17, the plurality of arm units 15 rotates about the shaft 14, which makes the respective support pins 16 revolve in the horizontal direction. Also, the plurality of support pins 16 and the arm units 15 are configured to be moved in the vertical direction together with the shaft 14 by driving the lift driving unit 18.
The plurality of support pins 16 and the arm units 15 are formed of a dielectric material. As a material used to form the plurality of support pins 16 and the arm units 15, for example, quartz, ceramics, or the like may be used.
The rotary driving unit 17 is not particularly limited as long as it can rotate the shaft 14. For example, the rotary driving unit 17 may have a motor (not shown), or the like. The lift driving unit 18 is not particularly limited as long as it can move up and down the shaft 14 and the movable connecting unit 19. For example, the lift driving unit 18 may have a ball screw (not shown), or the like. The rotary driving unit 17 and the lift driving unit 18 may be an integrated mechanism, or may have a configuration without the movable connecting unit 19. Also, the rotary mechanism for rotating the wafer W in the horizontal direction and the level position adjusting mechanism for adjusting the level position of the wafer W may have any other configuration as long as they can realize respective purposes thereof.
The exhaust device 6 includes, for example, a vacuum pump such as a dry pump. The microwave processing apparatus 1 further includes an exhaust pipe 21 connecting the exhaust port 13a and the exhaust device 6 and a pressure adjusting valve 22 installed in the middle of the exhaust pipe 21. The internal space of the processing container 2 is vacuum-exhausted by operating the vacuum pump of the exhaust device 6. Further, the microwave processing apparatus 1 may also perform a processing under atmospheric pressure, and in this case, the vacuum pump is not necessary. Instead of using the vacuum pump such as a dry pump as the exhaust device 6, exhaust equipment installed in facilities where the microwave processing apparatus 1 is installed may also be used.
The microwave processing apparatus 1 further includes the gas supply mechanism 5 that supplies a gas into the processing container 2. The gas supply mechanism 5 includes a gas supply device 5a having a gas supply source (not shown) and a plurality of pipes 23 (only two pipes are illustrated in
The gas supply device 5a is configured to supply a gas, for example, N2, Ar, He, Ne, O2, or H2, as a processing gas, into the processing container 2 through the plurality of pipes 23 according to a side flow manner. For the purpose of gas supply into the processing container 2, a gas supply means may be installed, for example, in a position (e.g., the ceiling part 11) facing the wafer W. Alternatively, instead of using the gas supply device 5a, an external gas supply device, which is not included in the configuration of the microwave processing apparatus 1, may be used. Although not shown, the microwave processing apparatus 1 further includes mass flow controllers and opening/closing valves installed in the middle of the pipes 23. Types and flow rates of gases supplied into the processing container 2 are controlled by the mass flow controllers and the shutoff valves.
The microwave processing apparatus 1 further includes a frame-shaped baffle plate 24 disposed between the side wall parts 12 and the circumference of the plurality of support pins 16 within the processing container 2. The baffle plate 24 has a plurality of baffle holes 24a formed to penetrate through the baffle plate 24 vertically. The baffle plate 24, while rectifying air in the region within the processing container 2 where the wafer W is to be located, serves to allow the air to flow toward the exhaust port 13a. The baffle plate 24 is formed of metal such as aluminum, an aluminum alloy, or stainless steel, for example. Also, the baffle plate 24 is not essential in the microwave processing apparatus 1 and may not be provided therein.
The microwave processing apparatus 1 further includes a plurality of radiation thermometers 26 for measuring a surface temperature of the wafer W and a temperature measuring unit 27 connected to the plurality of radiation thermometers 26. In
In the microwave processing apparatus 1 according to this embodiment, a microwave radiation space S is located within the processing container 2 defined by the ceiling part 11, the four side wall parts 12 and the baffle plate 24. Microwave is radiated to the microwave radiation space S from the plurality of microwave introducing ports 10, which are through holes formed in the ceiling part 11. Since the ceiling part 11, the four side wall parts 12 and the baffle plate 24 of the processing container 2 are all formed of metal, microwaves are reflected by these components and scattered within the microwave radiation space S. If the baffle plate 24 is not installed, a space within the processing container 2 defined by the ceiling part 11, the four side wall parts 12 and the bottom part 13 forms the microwave radiation space S.
Next, a configuration of the microwave introducing device 3 will be described with reference to
In this embodiment, the plurality of microwave units 30 has the same configuration. Each of the microwave units 30 includes a magnetron 31 that generates microwaves to process the wafer W, a waveguide 32 that acts as a transmission path to transmit microwaves generated by the magnetron 31 to the processing container 2, a transmission window 33A as a first microwave transmission window fixed to the ceiling part 11 so as to close the microwave introducing ports 10, and a rotary transmission window 33B as a second microwave transmission window installed to be closer to the magnetron 31 than the transmission window 33A. The magnetron 31 corresponds to a microwave source in the present disclosure.
As illustrated in
The magnetron 31 includes an anode (not shown) and a cathode (not shown) to which a high voltage supplied by the high voltage power supply unit 40 is applied. Also, a magnetron capable of oscillating microwaves of several frequencies may be used as the magnetron 31. As for microwaves generated by the magnetron 31, an optimal frequency may be selected for each treatment of an object to be processed. For example, in an annealing treatment, microwaves having a high frequency of 2.45 GHz, 5.8 GHz, or the like may be used. In particular, microwaves having a frequency of 5.8 GHz may be used in an annealing treatment.
The waveguide 32 has a square column shape with a rectangular cross-section and extends upward from the upper surface of the ceiling part 11 of the processing container 2. The magnetron 31 is connected to the vicinity of an upper end portion of the waveguide 32. A lower end portion of the waveguide 32 is in proximity to the upper surface of the rotary transmission window 33B. Microwaves generated by the magnetron 31 are introduced into the processing container 2 through the waveguide 32, the rotary transmission window 33B, and the transmission window 33A.
The transmission window 33A is formed of a dielectric material. As a material of the transmission window 33A, for example, quartz, ceramics, or the like may be used. A gap between the transmission window 33A and the ceiling part 11 is airtightly sealed by a seal member (not shown).
The rotary transmission window 33B includes, for example, two sheets of dielectric plates 51 and 52. The rotary transmission window 33B has a structure in which the relatively rotatable two sheets of dielectric plates 51 and 52 are vertically stacked. The lower dielectric plate 51 and the upper dielectric plate 52 may be brought into close contact with each other or may be spaced apart from each other. Each of the dielectric plates 51 and 52 is rotatably installed. More specifically, the dielectric plates 51 and 52 are independently rotatable in a plane perpendicular to the stacking direction thereof by a rotary driving unit 53. In this case, a direction of the rotational axis is identical to a traveling direction of the microwave transmitted through the waveguide 32. A driving mechanism of the rotary driving unit 53 may be, for example, a rack and pinion mechanism or the like. Configuration of the dielectric plates 51 and 52 will be described further down below in detail.
The microwave unit 30 further includes a circulator 34, a detector 35, and a tuner 36 installed in the middle of the waveguide 32, and a dummy load 37 connected to the circulator 34. The circulator 34, the detector 35, and the tuner 36 are installed in this order from the upper end portion side of the waveguide 32. The circulator 34 and the dummy load 37 form an isolator capable of separating a reflected wave from the processing container 2. More specifically, the circulator 34 guides a reflected wave from the processing container 2 to the dummy load 37, and the dummy load 37 converts the reflected wave guided by the circulator 34 into heat.
The detector 35 serves to detect a reflected wave from the processing container 2 in the waveguide 32. The detector 35 is configured as, for example, an impedance monitor, specifically, a standing wave monitor for detecting an electric field of a standing wave in the waveguide 32. The standing wave monitor may be formed by, for example, three pins protruding to an internal space of the waveguide 32. By detecting a location, phase and strength of an electric field of a standing wave by the standing wave monitor, a reflected wave from the processing container 2 may be detected. The detector 35 may be configured by a directional coupler capable of detecting a progressive wave and a reflected wave.
The tuner 36 serves to perform impedance matching (hereinafter, referred to simply as “matching”) between the magnetron 31 and the processing container 2. Matching by the tuner 36 is performed based on a detection result of the reflected wave in the detector 35. The tuner 36 may be configured by a conductive plate (not shown) installed to move into and out of the internal space of the waveguide 32. In this case, by controlling a protruding amount of the conductive plate to the internal space of the waveguide 32, an amount of electric power of the reflected wave may be adjusted to thereby adjust impedance between the magnetron 31 and the processing container 2.
The high voltage power supply unit 40 supplies a high voltage that generates microwaves for the magnetron 31. As illustrated in
The AC-DC conversion circuit 41 is a circuit for rectifying an alternating current (AC), e.g., 3-phase 200 V AC, from the commercial power source and converting the same into a direct current (DC) having a predetermined waveform. The switching circuit 42 is a circuit for controlling ON/OFF of the DC converted by the AC-DC conversion circuit 41. The switching circuit 42 performs phase-shifting pulse width modulation (PWM) control or pulse amplitude modulation (PAM) control, under the control of the switching controller 43, to generate a pulse-type voltage waveform. The boosting transformer 44 boosts the voltage waveform output from the switching circuit 42 to a predetermined size. The rectifying circuit 45 is a circuit for rectifying a voltage boosted by the boosting transformer 44 and supplying the rectified voltage to the magnetron 31.
The respective components of the microwave processing apparatus 1 are connected to the controller 8 and controlled by the controller 8. The controller 8 is typically a computer.
In the controller 8, the CPU 111 uses the RAM 112 as a working area and executes a program stored in the ROM 113 or the memory device 105 to thereby execute a heat treatment on the wafer W in the microwave processing apparatus 1 according to this embodiment. Specifically, the controller 8 controls the components of the microwave processing apparatus 1 (e.g., the microwave introducing device 3, the support device 4, the gas supply device 5a, the exhaust device 6, etc.) related to process conditions such as a temperature of the wafer W, a pressure within the processing container 2, a gas flow rate, microwave output, and a rotating speed of the wafer W.
Next, configuration examples of the rotary transmission window 33B used in this embodiment will be described with reference to
Further, as illustrated in
On the contrary, in
As illustrated in
On the contrary, in
On the contrary, in
Also, by using a metamaterial, the dielectric plates 51 and 52 may be configured such that permittivity thereof is gradually changed in the direction perpendicular to the stacking direction, respectively, like the cases of
Here, a relationship between a thickness of a dielectric plate and a phase of microwave will be described with reference to
Further, in some embodiments, if it is difficult to set the total thickness Tt of the transmission window 33A and the rotary transmission window 33B to 0.25λ/εr or smaller, a thickness t of each sheet of dielectric forming the transmission window 33A and the rotary transmission window 33B may be set to (n−0.125)λ/εr≦t≦(n+0.125)λ/εr (where λ and εr denote the same as mentioned above and n is a positive integer) such that plasma is not generated in the stacking boundaries.
Further, the present disclosure is not limited to the case of stacking two sheets of dielectric plates. That is, only one dielectric plate may be provided, or three or more dielectric plates may be stacked. In addition, a rotational angle of the dielectric plates may be arbitrarily determined within a range from 0 to 360 degrees, without being limited to 180 degrees as illustrated above.
As described above, in the microwave processing apparatus 1, the rotary transmission window 33B includes the dielectric plates 51 and 52 having permittivity which is not uniform in the direction perpendicular to the traveling direction of the microwave transmitted through the waveguide 32. Also, in the microwave processing apparatus 1, by rotating any one or both of the dielectric plates 51 and 52 by a certain angle in a plane perpendicular to the stacking direction, the traveling direction of microwave that transmits through the rotary transmission window 33B may be changed to thereby adjust an electric field strength distribution in the microwave radiation space S within the processing container 2. Thus, in the microwave processing apparatus 1, unevenness of heating temperatures within the plane of the wafer W can be suppressed by the rotary transmission window 33B, thus performing a uniform annealing treatment within the plane of the wafer W.
Next, a microwave processing method performed in the microwave processing apparatus 1 will be described. First, a command is input from the input device 102 of the controller 8 to perform an annealing treatment in the microwave processing apparatus 1. Thereafter, upon receipt of the command, the main controller 101 reads a recipe stored in the memory device 105 or the computer-readable recording medium 115. Subsequently, a control signal is transmitted from the main controller 101 to each of the end devices (for example, the microwave introducing device 3, the support device 4, the gas supply device 5a, the exhaust device 6, etc.) of the microwave processing apparatus 1, so that the annealing treatment may be executed under conditions based on the recipe.
Thereafter, the gate valve GV is opened, and the wafer W is loaded into the processing container 2 through the gate valve GV and the loading/unloading port 12a by a transfer device (not shown) and placed on the plurality of support pins 16. And then, the plurality of support pins 16 for supporting the wafer W is moved vertically by the lift driving unit 18 of the support device 4 so as to be set to a predetermined level position.
Thereafter, the gate valve GV is closed, and if necessary, the interior of the processing container 2 is vacuum-evacuated by the exhaust device 6. If necessary, a processing gas is introduced into the processing container 2 by the gas supply device 5a. The internal space of the processing container 2 is adjusted to be a predetermined pressure by adjusting an air exhaust amount and a supply amount of the processing gas. If necessary, the wafer W is rotated at a predetermined speed in the horizontal direction by driving the rotary driving unit 17 under the control of the controller 8. Also, the rotation of the wafer W may be discontinuous, rather than being continuous.
Thereafter, a voltage is applied from the high voltage power supply unit 40 to the magnetron 31 to generate microwaves. Microwaves generated by the magnetron 31 propagate through the waveguide 32, are transmitted through the rotary transmission window 33B and the transmission window 33A, and are introduced to a space above the wafer W within the processing container 2. In this embodiment, a plurality of magnetrons 31 sequentially generates microwaves, and the microwaves are alternately introduced into the processing container 2 from each of microwave introducing ports 10. In this embodiment, before microwaves are introduced or while microwaves are being introduced, the dielectric plate 51 and/or 52 of the rotary transmission window 33B is rotated to change a deflection angle of the microwaves, whereby a distribution of microwaves may be finely controlled in the microwave radiation space S. Further, in a case in which the wafer W is processed by rotating the dielectric plate 51 and/or 52 of the rotary transmission window 33B while microwaves are being introduced, the dielectric plate 51 and/or 52 may be intermittently rotated at certain intervals or continuously rotated. By rotating the dielectric plate 51 and/or 52 of the rotary transmission window 33B in this manner, positions of nodes and anti-nodes of a standing wave of the microwaves can be changed in the microwave radiation space S, whereby the wafer W may be uniformly processed within the plane. Also, the plurality of magnetron 31 may simultaneously generate a plurality of microwaves and the microwaves may be simultaneously introduced from the respective microwave introducing ports 10 into the processing container 2.
The microwaves introduced into the processing container 2 are irradiated to the wafer W, and the wafer W is rapidly heated by electromagnetic wave heating such as joule-heating, magnetic heating, or induction heating. As a result, an annealing treatment is performed on the wafer W.
During the annealing treatment, the wafer W may be rotated to reduce deflection of microwaves irradiated to the wafer W, thus making a heating temperature within the plane of the wafer W uniform.
When a control signal for terminating the annealing treatment is transmitted from the main controller 101 to each of the end devices of the microwave processing apparatus 1, generation of microwaves is stopped, rotation of the wafer W is stopped, supply of the treatment gas is stopped, and thus the annealing treatment on the wafer W is terminated.
After the annealing treatment for a predetermined period of time or a cooling treatment after the annealing treatment is terminated, the gate valve GV is opened, a level position of the wafer W is adjusted by the support device 4, and the wafer W is then unloaded by the transfer device (not shown).
In the process of manufacturing a semiconductor device, for example, the microwave processing apparatus 1 may be desirably used for the purpose of an annealing treatment for activating doping atoms implanted in a diffusion layer, or the like.
As described above, in the microwave processing apparatus 1 according to this embodiment, a distribution of microwaves in the processing container 2 can be finely adjusted, and thus the wafer W can be uniformly heated within the plane thereof.
Next, a microwave processing apparatus according to a second embodiment of the present disclosure will be described with reference to
As illustrated in
The dielectric members 54 and 55 have a configuration in which thicknesses thereof are changed in a traveling direction of a microwave 200 transmitted through the waveguide 32. Specifically, the dielectric member 54 has a sloped surface 54a and has a wedge-shaped cross-section, and the dielectric member 55 has a sloped surface 55a and has a wedge-shaped cross-section. The rotary transmission window 33B has a structure in which the two dielectric members 54 and 55 vertically overlap such that the sloped surfaces 54a and 55a thereof face each other. The lower dielectric member 54 and the upper dielectric member 55 may be brought into close contact with each other or may be spaced apart from one another.
Each of the dielectric members 54 and 55 is rotatably installed. That is, the dielectric members 54 and 55 are configured to be rotated about independent and different rotational shafts, respectively, by the rotary driving unit 53 (see
When only the upper dielectric member 55 is rotated, for example, by about 180 degrees from the state of
In this embodiment, in
On the contrary, in the state of
As described above, in the microwave processing apparatus according to this embodiment, the rotary transmission window 33B includes the dielectric members 54 and 55 having a configuration in which thicknesses thereof are changed, and thus, by rotating any one or both of the dielectric members 54 and 55 by a predetermined angle, a certain incident angle, rather than a right angle, may be formed with respect to the microwave 200 transmitted in the waveguide 32. By doing so, a distribution of electric field strength in the microwave radiation space S within the processing container 2 may be adjusted by changing a traveling direction of the microwave 200 that transmits through the rotary transmission window 33B. Thus, in the microwave processing apparatus of this embodiment, unevenness in heating temperatures within the plane of the wafer W can be suppressed by the rotary transmission window 33B, thus performing a uniform annealing treatment within the plane of the wafer W.
Other configurations and effects of this embodiment are identical to those of the first embodiment.
Further, the present disclosure is not limited to the foregoing embodiments and may be variously modified. For example, the microwave processing apparatus according to the present disclosure is not limited to the case in which a semiconductor wafer is used as a substrate, and may also be applied to, for example, a microwave processing apparatus in which a substrate of a solar battery panel or a substrate for a flat panel display is used as a substrate.
Also, in the microwave processing apparatus, the number of microwave units 30 (the number of magnetrons 31) or the number of microwave introducing ports 10 are not limited to the number mentioned in the foregoing embodiments.
According to the present disclosure in some embodiments, since the microwave processing apparatus includes the second microwave transmission windows for changing a traveling direction of microwaves, it is possible to finely adjust a distribution of electric field strength in a microwave radiation space within the processing container. Thus, according to the microwave processing apparatus of the present disclosure, the wafer W can be uniformly heated within the plane thereof.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosures. Indeed, the embodiments described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosures. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosures.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-007408 | Jan 2014 | JP | national |
