JP2007227201A - Plasma generating device and workpiece treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To output plasma with a plume of uniformed size from each plasma generating nozzle for a long time. <P>SOLUTION: A power meter 100 adjusts the value of bias current Ib to be supplied to a microwave generator 20 and controls the microwave generator 20 so that the power efficiency of the microwave outputted from the microwave generator 20 keeps a target value. As the target value, a value such that plasma with a uniform size of plume is released from each plasma generating nozzle 31 is adapted. Consequently, plasma with a plume of uniformed size can be generated from each plasma generating nozzle 31. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plasma generator capable of purifying or modifying the surface of a workpiece by irradiating plasma on a workpiece to be processed such as a substrate, and a workpiece processing apparatus using the plasma generator.

2. Description of the Related Art In recent years, a technique is known in which a workpiece to be processed such as a semiconductor substrate is irradiated with plasma to remove organic contaminants on the surface, surface modification, etching, thin film formation, or thin film removal. Patent Document 1 discloses a technique for controlling the discharge state of plasma or reaction gas to be constant based on the radiation spectrum of plasma or reaction gas in a low-temperature plasma processing apparatus that activates reaction gas with plasma. ing.
JP 62-228482 A

  However, in Patent Document 1, there is no description regarding that the plume emits uniform plasma from each of the plurality of plasma generation nozzles, and there is room for improvement in this regard. In particular, when irradiating a workpiece with plasma from a plurality of plasma generating nozzles, it is possible to efficiently remove organic matter from the workpiece or to remove the surface unless a uniform plume plasma is stably irradiated from each plasma generating nozzle for a long time. Cannot be modified.

  An object of the present invention is to provide a plasma generating apparatus and a work processing apparatus capable of stably outputting a plasma with a uniform plume from each plasma generating nozzle for a long time.

  A microwave generator according to the present invention includes a microwave generator that generates a microwave, a waveguide that propagates the microwave generated by the microwave generator, and a gas supply that supplies a gas to be converted into plasma And a plurality of plasma generating nozzles that are arranged in the waveguide and receive the microwaves and turn the gas supplied from the gas supply unit into plasma based on the received microwave energy. The plasma generation unit, the microwave measurement unit that measures the power of the microwave output from the microwave generation unit, and the plasma generated plume from each plasma generation nozzle are emitted in a substantially uniform size. A target value storage unit for storing a target value of a predetermined microwave power and a microwave measured by the microwave measurement unit. As the power of the filtered keep the target value, characterized in that it comprises a microwave controller for adjusting the microwave power output from the microwave generation part.

  According to this configuration, the microwave power generated by the microwave generation unit is measured by the microwave measurement unit, and the microwave generation unit is controlled so that the measured microwave power becomes the target value. . Here, the target value is a value that can generate a plume of uniform size from each plasma generating nozzle. That is, the microwave generation unit is feedback-controlled so that plasma having a uniform plume size is generated from each plasma generation nozzle. Therefore, each plasma generating nozzle constituting the plasma generating unit can stably generate plasma with a uniform plume size for a long time.

  Further, according to the above configuration, the microwave control unit adjusts a bias current supplied to the microwave generation unit in order to generate the microwave in the microwave generation unit. Is preferably controlled.

  According to this configuration, since the microwave generator is controlled by adjusting the bias current supplied to the microwave generator, the microwave power can be more accurately maintained at a constant magnitude.

  In the above configuration, it is preferable to further include a gas supply control unit that controls the gas supply unit so that a gas flow rate supplied by the gas supply unit maintains a constant value.

  According to this configuration, since the gas supply unit is controlled so that the gas flow rate is maintained at a constant value, the gas flow rate supplied to each plasma generation nozzle is constant, and each plasma generation nozzle has a larger plume. A uniform plasma can be generated.

  A workpiece processing apparatus according to the present invention includes the plasma generator according to any one of claims 1 to 3, and irradiates the workpiece with plasma emitted by the plasma generator.

  According to this configuration, each plasma generation nozzle constituting the plasma generation unit can generate plasma with a uniform plume size, and has a surface modification effect and an organic matter removal effect on the workpiece irradiated with plasma. Can be increased.

  According to the present invention, feedback control is performed so that the power of the microwave output from the microwave generator is constant, so that stable plume plasma can be generated for a long time.

  FIG. 1 is a perspective view showing an overall configuration of a work processing apparatus S according to an embodiment of the present invention. The workpiece processing apparatus S includes a plasma generation unit PU (plasma generation apparatus) that generates plasma and irradiates the workpiece W, which is an object to be processed, with the plasma, and a predetermined route that passes the workpiece W through the plasma irradiation region. It is comprised from the conveyance means C which conveys. 2 is a perspective view of the plasma generation unit PU in which the line-of-sight direction is different from that in FIG. 1, and FIG. 3 is a partially transparent side view. 1 to 3, the XX direction is the front-rear direction, the Y-Y direction is the left-right direction, the ZZ direction is the up-down direction, the -X direction is the front direction, the + X direction is the rear direction,- Y will be described as a left direction, + Y direction as a right direction, -Z direction as a downward direction, and + Z direction as an upward direction.

  The plasma generation unit PU is a unit capable of generating plasma at normal temperature and pressure using microwaves. In general, the waveguide 10 propagates microwaves, and one end side of the waveguide 10 ( Microwave generator 20 arranged on the left side to generate microwaves of a predetermined wavelength, plasma generator 30 provided on waveguide 10, and arranged on the other end side (right side) of waveguide 10 to reflect microwaves The sliding short 40 to be performed, the circulator 50 for separating the reflected microwaves from the microwaves emitted to the waveguide 10 so as not to return to the microwave generator 20, and the dummy load 60 for absorbing the reflected microwaves separated by the circulator 50. The stub tuner 70 that performs impedance matching and the power meter 100 are provided. The conveying means C includes a conveying roller 80 that is rotationally driven by a driving means (not shown). In the present embodiment, an example in which a flat workpiece W is conveyed by the conveying means C is shown.

  The waveguide 10 is made of a nonmagnetic metal such as aluminum, has a long tubular shape with a rectangular cross section, and propagates the microwave generated by the microwave generator 20 toward the plasma generator 30 in the longitudinal direction thereof. Is. The waveguide 10 is composed of a connected body in which a plurality of divided waveguide pieces are connected to each other by flange portions, and the first conductor on which the microwave generator 20 is mounted in order from one end side. The wave guide piece 11, the fourth wave guide piece 14 to which the power meter 100 is assembled, the second wave guide piece 12 to which the stub tuner 70 is assembled, and the third wave guide piece provided with the plasma generator 30. 13 is connected. A circulator 50 is interposed between the first waveguide piece 11 and the fourth waveguide piece 14, and a sliding short 40 is connected to the other end side of the third waveguide piece 13.

  Each of the waveguide pieces 11 to 14 is assembled in a rectangular tube shape using an upper plate, a lower plate, and two side plates made of a metal flat plate, and flange plates are attached to both ends thereof. Yes. In addition, you may make it use the rectangular waveguide piece formed by extrusion molding, the bending process of a plate-shaped member, etc., or a non-dividing type | mold waveguide irrespective of the assembly of such a flat plate. In addition, the waveguide is not limited to a rectangular cross section, and for example, a waveguide having an elliptical cross section can be used. Furthermore, not only a nonmagnetic metal but a waveguide can be comprised with the various members which have a waveguide effect | action.

  The microwave generator 20 includes, for example, an apparatus main body portion 21 including a microwave generation source such as a magnetron that generates a microwave of 2.45 GHz, and the microwave generated by the apparatus main body portion 21 inside the waveguide 10. And a microwave transmission antenna 22 that emits light to the outside. In the plasma generation unit PU according to the present embodiment, for example, a continuously variable microwave generator 20 that can output microwave energy of 1 W to 3 kW is preferably used.

  As shown in FIG. 3, the microwave generation device 20 has a configuration in which a microwave transmission antenna 22 protrudes from the device main body 21, and is fixed in a mode of being placed on the first waveguide piece 11. Has been. Specifically, the apparatus main body 21 is placed on the upper surface plate 11U of the first waveguide piece 11, and the microwave transmitting antenna 22 is inside the first waveguide piece 11 through the through hole 111 formed in the upper surface plate 11U. The waveguide space 110 is fixed so as to protrude. With this configuration, the microwave of 2.45 GHz, for example, emitted from the microwave transmission antenna 22 is directed from one end side (left side) to the other end side (right side) by the waveguide 10. Propagated.

The plasma generation unit 30 includes eight plasma generation nozzles 31 that are arranged in a row in the left-right direction on the lower surface plate 13B of the third waveguide piece 13 (the surface facing the workpiece to be processed). Configured. The width of the plasma generation unit 30, that is, the arrangement width in the left-right direction of the eight plasma generation nozzles 31 is a width that substantially matches the size t in the width direction orthogonal to the conveying direction of the flat workpiece W. Thereby, the plasma processing can be performed on the entire surface of the workpiece W (the surface facing the lower surface plate 13B) while the workpiece W is being conveyed by the conveying roller 80. The arrangement interval of the eight plasma generating nozzles 31 is preferably determined according to the wavelength lambda _G of the microwave propagating through the waveguide 10. For example, it is desirable to arrange the plasma generating nozzles 31 at a ½ pitch and a ¼ pitch of the wavelength λ _{G. When} a microwave of 2.45 GHz is used, since λ _G = 230 mm, 115 mm (λ _G / 2) The plasma generating nozzles 31 may be arranged at a pitch or 57.5 mm (λ _G / 4) pitch.

  4 is an enlarged side view showing two plasma generation nozzles 31 (one plasma generation nozzle 31 is drawn as an exploded view), and FIG. 5 is a cross-sectional view taken along line AA in FIG. The plasma generating nozzle 31 includes a central conductor 32 (internal conductor), a nozzle body 33 (external conductor), a nozzle holder 34, a seal member 35, and a protective tube 36.

  The center conductor 32 is made of a highly conductive metal such as copper, aluminum, or brass, and is made of a rod-like member having a diameter of about 1 to 5 mm. The upper end 321 side of the center conductor 32 is a lower plate 13B of the third waveguide piece 13. While vertically penetrating and projecting into the waveguide space 130 by a predetermined length (this projecting portion is referred to as a receiving antenna unit 320), the lower end 322 is substantially flush with the lower end edge 331 of the nozzle body 33. Is arranged. Microwave energy (microwave power) is applied to the central conductor 32 when the receiving antenna unit 320 receives the microwave propagating through the waveguide 10. The central conductor 32 is held by a seal member 35 at a substantially intermediate portion in the length direction.

  The nozzle body 33 is a cylindrical body made of a highly conductive metal and having a cylindrical space 332 that houses the central conductor 32. The nozzle holder 34 is also made of a highly conductive metal, and has a relatively large-diameter lower holding space 341 that holds the nozzle body 33 and a relatively small-diameter upper holding space 342 that holds the seal member 35. It is a state. On the other hand, the seal member 35 is made of a heat-resistant resin material such as Teflon (registered trademark) or an insulating member such as ceramic, and has a holding hole 351 for holding the central conductor 32 fixedly on its central axis. It consists of a body

  The nozzle body 33 is provided in an annularly projecting manner from the upper side, an upper body part 33U fitted in the lower holding space 341 of the nozzle holder 34, an annular recess 33S for holding a gas seal ring 37 described later. A flange portion 33F and a lower body portion 33B protruding from the nozzle holder 34 are provided. In addition, a communication hole 333 for supplying a predetermined processing gas to the cylindrical space 332 is formed in the upper body portion 33U.

  The nozzle body 33 functions as an external conductor disposed around the central conductor 32. The central conductor 32 is a cylindrical space with a predetermined annular space H (insulation interval) secured around it. It is inserted on the central axis of 332. The nozzle body 33 has a nozzle holder such that the outer peripheral portion of the upper body portion 33U is in contact with the inner peripheral wall of the lower holding space 341 of the nozzle holder 34 and the upper end surface of the flange portion 33F is in contact with the lower end edge 343 of the nozzle holder 34. 34 is fitted. The nozzle body 33 is preferably attached to the nozzle holder 34 with a detachable fixing structure using, for example, a plunger or a set screw.

  The nozzle holder 34 includes an upper body portion 34U (corresponding approximately to the position of the upper holding space 342) and a lower surface plate 13B that are closely fitted in a through hole 131 formed in the lower surface plate 13B of the third waveguide piece 13. And a lower body portion 34B (substantially corresponding to the position of the lower holding space 341). A gas supply hole 344 for supplying a processing gas to the annular space H is formed in the outer periphery of the lower body portion 34B. Although not shown, a pipe joint or the like for connecting a terminal portion of a gas supply pipe for supplying a predetermined processing gas is attached to the gas supply hole 344. The gas supply hole 344 and the communication hole 333 of the nozzle body 33 are set so that they are in communication with each other when the nozzle body 33 is fitted into the nozzle holder 34 at a fixed position. A gas seal ring 37 is interposed between the nozzle body 33 and the nozzle holder 34 in order to suppress gas leakage from the abutting portion between the gas supply hole 344 and the communication hole 333.

  A plurality of the gas supply holes 344 and the communication holes 333 may be perforated at equal intervals in the circumferential direction, and are not perforated in the radial direction toward the center. The gas may be perforated in the tangential direction of the outer peripheral surface of the cylindrical space 332 so as to swirl the gas. Further, the gas supply hole 344 and the communication hole 333 are not perpendicular to the central conductor 32, and may be formed obliquely from the upper end 321 side to the lower end 322 side in order to improve the flow of the processing gas. Good.

  The seal member 35 has a lower end edge 352 in contact with an upper end edge 334 of the nozzle body 33 and an upper end edge 353 in contact with an upper end locking portion 345 of the nozzle holder 34 in the upper holding space 342 of the nozzle holder 34. Is retained. That is, the upper holding space 342 is assembled so that the seal member 35 supporting the central conductor 32 is fitted and the lower end edge 352 of the nozzle body 33 is pressed by the upper end edge 334. is there.

  The protective tube 36 (not shown in FIG. 5) is made of a quartz glass pipe or the like having a predetermined length, and has an outer diameter substantially equal to the inner diameter of the cylindrical space 332 of the nozzle body 33. In order to improve the corrosion resistance of the lower end edge 331 of the nozzle body 33, the protective tube 36 is inserted into the cylindrical space 332 so that a part thereof protrudes from the lower end edge 331 of the nozzle body 33. Note that the entire protective tube 36 may be accommodated in the cylindrical space 332 so that the tip end thereof coincides with the lower end edge 331 or enters the inner side of the lower end edge 331.

  As a result of the plasma generation nozzle 31 being configured as described above, the nozzle body 33, the nozzle holder 34, and the third waveguide piece 13 (waveguide 10) are in a conductive state (the same potential), Since the central conductor 32 is supported by the insulating seal member 35, it is electrically insulated from these members. Therefore, as shown in FIG. 6, when the microwave is received by the receiving antenna unit 320 of the central conductor 32 and the microwave power is supplied to the central conductor 32 in a state where the waveguide 10 is at the ground potential. An electric field concentration portion is formed in the vicinity of the lower end portion 322 and the lower end edge 331 of the nozzle body 33. In the present embodiment, the length of each central conductor 32 is set so that the plume of each plume from each plasma generating nozzle 31 is received when a microwave whose power is adjusted so that the central conductor 32 becomes a target value described later is received. A value is adopted such that a plasma having a uniform size is emitted.

  In this state, when an oxygen-based processing gas such as oxygen gas or air is supplied from the gas supply hole 344 to the annular space H, the processing gas is excited by the microwave power and the lower end of the central conductor 32 is excited. Plasma (ionized gas) is generated near the portion 322. Although this plasma has an electron temperature of tens of thousands of degrees, the gas temperature is a reactive plasma that is close to the outside temperature (a plasma in which the electron temperature indicated by electrons is extremely high compared to the gas temperature indicated by neutral molecules). It is a plasma generated under normal pressure.

  The processing gas thus converted into plasma is radiated from the lower edge 331 of the nozzle body 33 as a plume P by the gas flow provided from the gas supply hole 344. This plume P contains radicals. For example, when an oxygen-based gas is used as the processing gas, oxygen radicals are generated, and the plume P having an organic substance decomposition / removal action, a resist removal action, and the like can be obtained. In the plasma generation unit PU according to the present embodiment, since a plurality of plasma generation nozzles 31 are arranged, it is possible to generate a line-shaped plume P extending in the left-right direction.

  Incidentally, when an inert gas such as argon gas or nitrogen gas is used as the processing gas, the surface cleaning and surface modification of various substrates can be performed. Further, if a compound gas containing fluorine is used, the substrate surface can be modified to a water-repellent surface, and using a compound gas containing a hydrophilic group can modify the substrate surface to a hydrophilic surface. Furthermore, if a compound gas containing a metal element is used, a metal thin film layer can be formed on the substrate.

  The sliding short 40 is provided for optimizing the coupling state between the central conductor 32 provided in each plasma generation nozzle 31 and the microwave propagated inside the waveguide 10. The third wave guide piece 13 is connected to the right end of the third waveguide piece 13 so that the standing wave pattern can be adjusted by changing the microwave reflection position.

  FIG. 7 is a perspective view showing the internal structure of the sliding short 40. As shown in FIG. 7, the sliding short 40 includes a housing structure having a rectangular cross section similar to that of the waveguide 10, and a housing portion 41 having a hollow space 410 made of the same material as the waveguide 10. And a reflection block 42 housed in the hollow space 410, a rectangular block 43 that is integrally attached to the base end of the reflection block 42, and slides in the left-right direction in the hollow space 410 having a rectangular cross section, A nut 44 assembled to the rectangular block 43; a ball screw 45 that is screwed into the nut 44 to slide the rectangular block 43 and the reflecting block 42; and a stepping motor 46 that rotationally drives the ball screw 45; And a joint 47 that directly connects the output shaft 461 of the stepping motor 46 and the one end 451 of the ball screw 45.

  The reflection block 42 is formed by attaching an end plate 421 serving as a microwave reflection surface to one end of a cylindrical tubular portion 422 so as to face the waveguide space 130 of the third waveguide piece 13. The other end of the shape portion 422 is fixed to the rectangular block 43, and the other end portion 452 side of the ball screw 45 can be accommodated therein. The tubular portion 422 of the reflection block 42 may have a rectangular tubular shape similar to that of the rectangular block 43. A nut 44 is fitted in a hole 431 formed in the center of the rectangular block 43, and when the ball screw 45 screwed into the inner screw of the nut 44 rotates, the rectangular block 43 and the reflective block are rotated. 42 slides in the left-right direction. The standing wave pattern is optimized by adjusting the position of the end plate 421 by the movement of the reflection block 42. One end 451 of the ball screw 45 and the output shaft 461 of the stepping motor 46 are fixed to the joint 47 by screws 48 and rotate in conjunction with each other.

  The circulator 50 is composed of, for example, a waveguide-type three-port circulator with a built-in ferrite column. Of the microwaves once propagated toward the plasma generator 30, the plasma generator 30 returns without being consumed. The incoming reflected microwave is directed to the dummy load 60 without returning to the microwave generator 20. By arranging such a circulator 50, the microwave generator 20 is prevented from being overheated by the reflected microwave.

  FIG. 8 is a top view of the plasma generation unit PU for explaining the operation of the circulator 50. As shown, the first port 51 of the circulator 50 has a first waveguide piece 11, the second port 52 has a second waveguide piece 12, and the third port 53 has a dummy load 60. It is connected. Then, the microwave generated from the microwave transmission antenna 22 of the microwave generator 20 travels from the first port 51 to the second waveguide piece 12 via the second port 52 as indicated by an arrow a. On the other hand, the reflected microwave incident from the second waveguide piece 12 side is deflected from the second port 52 toward the third port 53 and incident on the dummy load 60 as indicated by the arrow b. .

  The dummy load 60 is a water-cooled (or air-cooled) radio wave absorber that absorbs the reflected microwave and converts it into heat. The dummy load 60 is provided with a cooling water circulation port 61 for circulating cooling water therein so that heat generated by heat conversion of the reflected microwaves is exchanged with the cooling water. It has become.

  The stub tuner 70 is for impedance matching between the waveguide 10 and the plasma generation nozzle 31, and has three stub tuners arranged in series on the upper surface plate 12 U of the second waveguide piece 12 at a predetermined interval. Units 70A to 70C are provided. FIG. 9 is a perspective side view showing an installation state of the stub tuner 70. As shown in the figure, the three stub tuner units 70A to 70C have the same structure, and the stub 71 protruding into the waveguide space 120 of the second waveguide piece 12 and one end 721 are directly connected to the stub 71. The cylindrical body 72, the nut 73 fixed to the other end 722 of the cylindrical body 72, and the nut 73 are screwed together, and the nut 73 and the cylindrical body 72 and the stub 71 connected thereto are inserted into the waveguide space 120. A ball screw 75 that moves in and out, a stepping motor 76 that rotationally drives the ball screw 75, a joint 77 that directly connects the output shaft 761 of the stepping motor 76 and one end portion 751 of the ball screw 75, and an outer jacket 74 that will be described later It is fixed to the inner peripheral surface and is formed in a cylindrical shape to accommodate the cylindrical body 72 and the stub 71, and has an elongated hole 791 formed in the axial direction. The pin 723 erected on the cylindrical body 72 slides in the elongated hole 791 to displace the cylindrical body 72 rotated by the ball screw 75 in the axial direction and guide the stub 71. The guide cylinder 79 is made to appear and disappear in the space 120, and the outer sleeve 74 holds these mechanisms. The output shaft 761 of the stepping motor 76 and the one end 751 of the ball screw 75 are fixed to the joint 77 by screws 78 and rotate in conjunction with each other.

  As shown in FIG. 3, the power meter 100 includes two power meters 100 </ b> A and 100 </ b> B arranged in series at a predetermined interval on the upper surface plate 14 </ b> U of the fourth waveguide piece 14. The two power meter units 100A and 100B have the same structure, and have a detection unit 101 that projects into the waveguide space 140 of the fourth waveguide piece 14 and detects the power of the propagated microwave. The power meter unit 100A on the microwave generator 20 side detects the power of the input wave to the plasma generator 30, and the power meter unit 100B on the plasma generator 30 side detects the power of the reflected wave from the plasma generator 30. To do.

  The conveyance means C includes a plurality of conveyance rollers 80 arranged along a predetermined conveyance path, and the conveyance roller 80 is driven by a driving means (not shown), so that the workpiece W to be processed is generated by the plasma generation. It is conveyed via the section 30. Here, examples of the workpiece W to be processed include a flat substrate such as a plasma display panel and a semiconductor substrate, a circuit substrate on which electronic components are mounted, and the like. Also, parts or assembled parts that are not flat-shaped can be processed, and in this case, a belt conveyor or the like may be employed instead of the conveying roller.

  Next, an electrical configuration of the work processing apparatus S according to the present embodiment will be described. FIG. 10 is a block diagram showing a control system of the work processing apparatus S. The control system includes an overall control unit 90, a microwave output control unit 91 including an output interface and a drive circuit, a gas flow rate control unit 92, a transfer control unit 93, a stub tuner drive unit 98, and a sliding short drive unit 99. An operation unit 95 that includes a display means, an operation panel, and the like, and gives a predetermined operation signal to the overall control unit 90; sensor input units 94 and 97 that include an input interface, an analog / digital converter, and the like; 971, a drive motor 931, and a flow rate control valve 923.

  The microwave output control unit 91 performs ON / OFF control and output intensity control of the microwave output from the microwave generator 20. The microwave output controller 91 generates the 2.45 GHz pulse signal and The operation control of the microwave generation by the apparatus main body 21 is performed.

  The gas flow rate control unit 92 controls the flow rate of the processing gas supplied to each plasma generation nozzle 31 of the plasma generation unit 30. Specifically, the opening degree of the flow rate control valve 923 provided in the gas supply pipe 922 connecting the processing gas supply source 921 such as a gas cylinder and each plasma generating nozzle 31 is adjusted. In the present embodiment, the gas flow control unit 92 adjusts the opening of each flow control valve 923 so that the opening of each flow control valve 923 has the same magnitude.

  The conveyance control unit 93 controls the operation of the drive motor 931 that rotationally drives the conveyance roller 80, and controls the start / stop of conveyance of the workpiece W, the conveyance speed, and the like.

  The overall control unit 90 includes a CPU, a ROM, a RAM, and the like, and controls the overall operation of the work processing apparatus S. The overall control unit 90 is input from the sensor input unit 97 according to an operation signal given from the operation unit 95. The measurement result of the conveyance speed of the workpiece W by the speed sensor 971 is monitored and the conveyance speed of the workpiece W is made constant.

  Specifically, the overall control unit 90 starts conveying the workpiece W based on a control program stored in advance in the ROM, guides the workpiece W to the plasma generation unit 30, and supplies a processing gas having a predetermined flow rate to each plasma. Plasma (plume P) is generated by supplying microwave power while supplying the generating nozzle 31, and the plume P is radiated on the surface of the workpiece W while it is conveyed. Thereby, a plurality of works W are processed continuously.

  The overall control unit 90 has functions of a bias current adjustment unit 901 and a target value storage unit 902. The bias current adjustment unit 901 monitors the measurement results of the power meter units 100A and 100B of the power meter 100 input from the sensor input unit 94 in response to the operation of the operator from the operation unit 95, and the measurement result. (A value obtained by subtracting the power of the reflected wave from the plasma generation unit 30 measured by the power meter unit 100B from the power of the input wave to the plasma generation unit 30 measured by the power meter unit 100A). Therefore, the value of the bias current Ib is adjusted so that the received microwave power and the power transmission efficiency at each plasma generation nozzle 31 are maintained at constant values. Specifically, when the difference between the measurement results is larger than the target value, the bias current adjusting unit 901 decreases the value of the bias current Ib bit by bit until the target value is reached, and the difference in the measurement result is the target value. If it is smaller than that, the value of the bias current Ib is increased bit by bit until the target value is reached. Thereby, the power of the microwave output from the microwave generator 20 is maintained at a constant value.

  The target value storage unit 902 stores a target value of the microwave power output from the microwave generator 20. As this target value, an experimentally obtained value is adopted so that the size of the plume P emitted from each plasma generating nozzle 31 becomes uniform. Therefore, by controlling the microwave generator 20 so that the difference between the measurement results captured by the sensor input unit 94 becomes a target value, plasma having a uniform plume size can be generated from each plasma generating nozzle 31. Can do.

  The D / A converter 903 has a resolution of a predetermined bit, for example, 10 bits, and an output terminal is connected to the anode electrode of the magnetron constituting the microwave generator 20, and is a digital output output from the bias current adjustment unit 901. The bias current Ib is converted into an analog bias current Ib and output to the microwave generator 20.

  FIG. 11 is a flowchart showing processing by the overall control unit 90. First, in step S1, when a power switch (not shown) is turned on by the user, the overall control unit 90 starts supplying power from a commercial power source to each circuit constituting the apparatus.

  In step S <b> 2, the overall control unit 90 outputs an open signal for adjusting the opening of the gas flow rate valve 923 to the gas flow rate control unit 92, opens all the flow rate control valves 923, and starts from the processing gas supply source 921. Is supplied to the plasma generating nozzle 31. Here, the gas flow rate control unit 92 adjusts the opening degree of each flow rate control valve 923 so that the opening degree of each flow rate control valve 923 becomes the same.

  In step S <b> 3, the microwave output control unit 91 outputs a microwave generation signal to the microwave output control unit 91, and the bias current adjustment unit 901 generates the microwave via the D / A converter 903. By outputting to the device 20, the microwave is generated from the microwave generator 20. Thereby, the microwave generator 20 outputs a microwave having a power corresponding to the bias current Ib. The eight plasma generating nozzles 31 irradiate the workpiece W conveyed by the conveying means C with plasma.

  In step S4, the bias current adjustment unit 901 determines whether or not a predetermined time has elapsed (for example, 3 seconds) after the processing of step S3, S7, or S9 is completed. The sensor input unit 94 takes in the measurement result by the power meter 100 and outputs it to the bias current adjustment unit 901 (S5). That is, the sensor input unit 94 captures the measurement results obtained by the power meter 100 at predetermined time intervals.

  In step S6, when the difference between the measurement results captured in step S5 is larger than the target value (YES in S6), the bias current adjustment unit 901 decreases the value of the bias current Ib by 1 bit (step S8). On the other hand, when the difference between the measurement results captured in step S5 is smaller than the target value (NO in S6, YES in S7), the bias current adjustment unit 901 increases the value of the bias current Ib by 1 bit (S9).

  As described above, according to the present microwave generator PU, the microwave generator 20 is feedback-controlled so that the difference between the measurement results from the power meter 100 output from the microwave generator 20 maintains the target value. Yes. Here, the target value is such a value that plasma having a uniform plume size is generated from each plasma generating nozzle 31. Therefore, each plasma generating nozzle 31 can generate a uniform plasma stably for a long time.

  The present invention may adopt the following aspects.

(1) In the above embodiment, an example in which a plurality of plasma generating nozzles 31 are arranged in a line has been shown. However, the nozzle arrangement may be appropriately determined according to the shape of the workpiece W, the power of the microwave power, and the like. For example, a plurality of rows of plasma generating nozzles 31 may be arranged in a matrix or in a staggered arrangement in the conveyance direction of the workpiece W.
(2) In the above-described embodiment, a mode in which a flat plate-like workpiece is placed on the upper surface of the conveyance roller 80 and conveyed as the conveyance means C is illustrated. However, for example, the workpiece is nipped between the upper and lower conveyance rollers. A mode in which the workpiece is stored in a predetermined basket or the like without using a conveyance roller and the basket or the like is conveyed by a line conveyor or the like, or a shape in which the workpiece is gripped by a robot hand or the like and conveyed to the plasma generating unit 30 It may be.
(3) In the above embodiment, a magnetron that generates a microwave of 2.45 GHz is illustrated as a microwave generation source. However, various high-frequency power sources other than the magnetron can be used, and a wavelength different from 2.45 GHz. Microwaves may be used.
(4) In the above embodiment, the fourth waveguide piece 14 to which the power meter 100 is assembled is provided between the circulator 50 and the second waveguide piece 12. However, the present invention is not limited to this, and the sliding short 40 and It may be provided between the third waveguide pieces 13.

  A workpiece processing apparatus and a plasma generation apparatus according to the present invention include an etching processing apparatus and a film forming apparatus for a semiconductor substrate such as a semiconductor wafer, a glass substrate such as a plasma display panel and a cleaning processing apparatus for a printed board, and a sterilization process for medical equipment The present invention can be suitably applied to an apparatus, a protein decomposition apparatus, and the like.

It is a perspective view which shows the whole structure of the workpiece processing apparatus which concerns on this invention. FIG. 2 is a perspective view of a plasma generation unit with a different line-of-sight direction from FIG. 1. It is a partial see-through | perspective side view of a workpiece | work processing apparatus. It is a side view which expands and shows two plasma generation nozzles (one plasma generation nozzle is drawn as an exploded view). It is the sectional view on the AA line side of FIG. It is a see-through | perspective side view for demonstrating the generation state of the plasma in a plasma generation nozzle. It is a see-through | perspective perspective view which shows the internal structure of a sliding short. It is a top view of the plasma generation unit for demonstrating the effect | action of a circulator. It is a see-through | perspective side view which shows the installation condition of a stub tuner. It is a block diagram which shows the control system of a workpiece processing apparatus. It is a flowchart which shows the process of a workpiece | work processing apparatus.

Explanation of symbols

10 Waveguide 20 Microwave generator (microwave generator)
30 Plasma generator 31 Plasma generator nozzle 32 Central conductor (internal conductor)
33 Nozzle body (external conductor)
34 Nozzle holder 344 Gas supply hole (gas supply part)
36 Protection tube 40 Sliding short 50 Circulator 60 Dummy load 70 Stub tuner 80 Conveying roller 90 Overall control unit 901 Bias current adjustment unit 902 Target value storage unit 903 D / A converter 91 Microwave output control unit 92 Gas flow rate control unit 921 Processing Gas supply source 922 Gas supply pipe 923 Flow rate control valve 93 Conveyance control unit 931 Drive motor 95 Operation unit 94, 97 Sensor input unit S Work processing device PU Plasma generator C Conveying means W Workpiece

Claims (4)

A microwave generator for generating microwaves;
A waveguide for propagating microwaves generated by the microwave generator;
A gas supply unit for supplying a gas to be converted into plasma;
Plasma in which a plurality of plasma generating nozzles that receive the microwaves and turn the gas supplied from the gas supply unit into plasma based on the received microwave energy are arranged and attached to the waveguide. Generating part,
A microwave measurement unit for measuring the power of the microwave output from the microwave generation unit;
A target value storage unit that stores a target value of a predetermined microwave power so that a plume of plasmaized gas is emitted from each plasma generation nozzle in a substantially uniform size;
A microwave control unit that adjusts the power of the microwave output from the microwave generation unit so that the microwave power measured by the microwave measurement unit maintains the target value. Plasma generator. The microwave generator adjusts the power of the microwave output by the bias current output from the microwave controller,
The plasma generation apparatus according to claim 1, wherein the microwave control unit adjusts the bias current to set a microwave power measured by the microwave measurement unit to a target value.   The plasma generating apparatus according to claim 1, further comprising a gas supply control unit that controls the gas supply unit so that a gas flow rate supplied by the gas supply unit maintains a constant value.   A workpiece processing apparatus comprising the plasma generation device according to claim 1, wherein the workpiece is irradiated with plasma emitted from the plasma generation device.

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