Microwave control method

A microwave control method is used in a microwave plasma processing apparatus including a microwave generation unit, a waveguide for guiding a microwave generated by the microwave generation unit, a tuner for controlling a position of a movable short-circuiting plate, and a stub provided between the tuner and an antenna in the waveguide and insertable into an inner space of the waveguide. The method includes detecting the position of the movable short-circuiting plate controlled by the tuner for the microwave outputted by the microwave generation unit, determining whether or not a difference between a reference position and the detected position of the movable short-circuiting plate is within a tolerable range, and controlling an insertion length of the stub into the inner space of the waveguide when it is determined that the difference between the position of the movable short-circuiting plate and the reference position is not within the tolerable range.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2016-137460 filed on Jul. 12, 2016, the entire contents of which is incorporated herein by reference.

FIELD OF THE INVENTION

The disclosure relates to a microwave control method.

BACKGROUND OF THE INVENTION

A plasma processing apparatus is used in manufacturing electronic devices such as semiconductor devices and the like. A plasma processing apparatus disclosed in Japanese Patent Application Publication No. 2015-022940 is configured to excite a gas by using a microwave. This apparatus includes a microwave generation unit, an antenna, and a4E tuner disposed in a waveguide between the microwave generation unit and the antenna. The4E tuner has four movable short-circuiting plates. By operating the movable short-circuiting plates, impedance matching is automatically performed. Positions of the movable short-circuiting plates after the matching are referred to as tuner positions.

In the case of a plasma processing apparatus using a microwave such as the plasma processing apparatus disclosed in Japanese Patent Application Publication No. 2015-022940, a ceiling plate is consumed by use. In that case, an unstable plasma may be generated. The following is description of estimated mechanism of the generation of the unstable plasma. A resonance frequency exists between the tuner and the plasma. When the ceiling plate is consumed by use, the tuner position is moved. The resonance frequency is changed by the movement of the tuner position. When the changed resonance frequency coincides with a power frequency of a plasma, an unstable plasma is generated. When the unstable plasma is generated, a maintenance operation such as exchange of the ceiling plate or the like is required. Therefore, in this technical field, a microwave control method capable of improving availability of the plasma processing apparatus is required.

SUMMARY OF THE INVENTION

In accordance with an aspect, there is provided a microwave control method used in a microwave plasma processing apparatus including a microwave generation unit configured to generate a microwave having a power corresponding to a set power, a waveguide configured to guide the microwave generated by the microwave generation unit to an antenna of a chamber main body, a tuner provided in the waveguide and configured to control a position of a movable short-circuiting plate such that an impedance of the microwave generation unit side is matched with an impedance of the antenna side, and a stub provided between the tuner and the antenna in the waveguide and insertable into an inner space of the waveguide.

The microwave control method includes: a detection step of detecting the position of the movable short-circuiting plate which is controlled by the tuner for the microwave outputted by the microwave generation unit; a determination step of determining whether or not a difference between a reference position and the detected position of the movable short-circuiting plate is within a tolerable range; and a control step of controlling an insertion length of the stub into the inner space of the waveguide when it is determined that the difference between the position of the movable short-circuiting plate and the reference position is not within the tolerable range.

In this microwave control method, when the difference between the position of the movable short-circuiting plate and the reference position is not within the tolerable range, the insertion length of the stub provided between the tuner and the antenna (length of the stub inserted into the inner space of the waveguide) is controlled. In other words, when the tuner position is deviated from the tolerable range by the consumption of the ceiling plate, the insertion length of the stub is controlled. Accordingly, the resonance frequency between the tuner and the plasma can be changed, which makes it possible to avoid the generation of an unstable plasma. As a result, the availability of the plasma processing apparatus can be improved.

In the control step, the stub may be inserted into the inner space of the waveguide by a predetermined length, and the control step, the detection step, and the determination step are repeatedly executed until it is determined that the difference between the position of the movable short-circuiting position and the reference position is within the tolerable range in the determination step.

With this configuration, the tuner position can be within the tolerable range while checking the validity of the change.

The microwave generation unit may be configured to change a frequency of the microwave, and the microwave control method may further include: a change step of changing the insertion length of the stub to a threshold and changing the frequency of the microwave generated by the microwave generation unit when it is determined that the difference between the position of the movable short-circuiting plate and the reference position is not within the tolerable range and when the controlled insertion length of the stub which is not smaller than the threshold. Since the stub is inserted into the inner space of the waveguide, the reflection wave power may be increased by excessive insertion of the stub. In other words, when the insertion length of the stub exceeds the threshold value, the control using the stub has limitation. Therefore, in that case, the frequency of the microwave is changed by setting the insertion length of the stub to the threshold value. As such, when the control using the stub has limitation, it is possible to control the tuner position to be within the tolerable range by employing another approach in which the frequency of the microwave is changed.

The microwave control method may further include: a step of stopping the repeated execution of the control step, the detection step and the determination step and outputting alarm when it is determined that the difference between the position of the movable short-circuiting plate and the reference position is not within the tolerable range in the determination step and when the controlled insertion length of the stub is not smaller than the threshold. As such, when the control using the stub has limitation, the maintenance can be promoted by outputting alarm.

In accordance with another aspect, there is provided a microwave control method used in a microwave plasma processing apparatus including a microwave generation unit configured to generate a microwave having a power corresponding to a set power, a waveguide configured to guide the microwave generated by the microwave generation unit to an antenna of a chamber main body, a tuner provided in the waveguide and configured to control a position of a movable short-circuiting plate such that an impedance of the microwave generation unit side is matched with an impedance of the antenna side, and a stub provided between the tuner and the antenna in the waveguide and insertable into an inner space of the waveguide

The microwave control method includes: a detection step of detecting a reflection wave power of the microwave outputted by the microwave generation unit; a determination step of determining whether or not a difference between a reference reflection wave power and the detected reflection wave power is within a tolerable range; and a control step of controlling an insertion length of the stub into the inner space of the waveguide when it is determined that the difference between the reference reflection wave power and the detected reflection wave power is not within the tolerable range.

In this microwave control method, when the difference between the reflection wave power and the reference reflection wave power is not within the tolerable range, the insertion length of the stub provided between the tuner and the antenna (length of insertion of the stub into the inner space of the waveguide) is controlled. In other words, when the reflection wave power is deviated from the tolerable range by the consumption of the ceiling plate, the insertion length of the stub is controlled. Accordingly, the resonance frequency between the tuner and the plasma can be changed, which makes it possible to avoid the generation of an unstable plasma. As a result, the availability of the plasma processing apparatus can be improved.

In the control step, the stub may be inserted into the inner space of the waveguide by a predetermined length and the control step, the detection step and the determination step may be repeatedly executed until it is determined that the difference between the reflection wave power and the reference reflection wave power is within the tolerable range in the determination step. With such configuration, the reflection wave power can be within the tolerable range while checking the validity of the change.

The microwave generation unit may be configured to change a frequency of the microwave, and the microwave control method may further include: a change step of changing the insertion length of the stub to a threshold and changing the frequency of the microwave generated by the microwave generation unit when it is determined that the difference between the position of the movable short-circuiting plate and the reference position is not within the tolerable range in the determination step and when the controlled insertion length of the stub is not smaller than the threshold.

Since the stub is inserted into the inner space of the waveguide, the reflection wave power may be increased by excessive insertion of the stub. In other words, when the insertion length of the stub exceeds the threshold, the control using the stub has limitation. Therefore, in that case, the frequency of the microwave is changed by setting the stub to the threshold. As such, when the control using the stub has limitation, it is possible to control the reflection wave power to be within the tolerable range by employing another approach in which the frequency of the microwave is changed.

The microwave control method may further include: a step of stopping the repeated execution of the control step, the detection step and the determination step and outputting alarm when it is determined that the difference between the position of the movable short-circuiting plate and the reference position is not within the tolerable range in the determination step and when the controlled insertion length of the stub is not smaller than the threshold. As such, when the control using the stub is limited, the maintenance can be promoted by outputting alarm.

As described above, the availability of the plasma processing apparatus can be improved.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, various embodiments will be described with reference to the accompanying drawings. Like reference numerals will be used for like or corresponding parts throughout the drawings.

First Embodiment

FIG. 1shows a plasma processing apparatus (microwave plasma processing apparatus)1to which a microwave control method according to a first embodiment is applied. The plasma processing apparatus1shown inFIG. 1includes a chamber main body12and a microwave output device16. The plasma processing apparatus1may further include a stage14, an antenna18and a dielectric window20.

The chamber main body12has therein a processing space S. The chamber main body12has a sidewall12aand a bottom portion12b. The sidewall12ahas a substantially cylindrical shape. A central axis of the sidewall12asubstantially coincides with an axis Z extending in a vertical direction. The bottom portion12bis provided at a lower end side of the sidewall12a. A gas exhaust opening12his provided at the bottom portion12b. An upper end portion of the sidewall12ais opened.

A dielectric window20is provided at the upper end portion of the sidewall12a. The dielectric window20has a bottom surface20afacing the processing space S. The dielectric window20blocks the opening formed at the upper end portion of the sidewall12a. An O-ring19is provided between the dielectric window20and the upper end portion of the sidewall12a. The chamber main body12is reliably sealed by the O-ring19.

The stage14is accommodated in the processing space S. The stage14is disposed to face the dielectric window20in the vertical direction. The processing space S is provided between the dielectric window20and the stage14. The stage14is configured to support a target object WP (e.g., wafer) mounted thereon.

In one embodiment, the stage14includes a base14aand an electrostatic chuck14c. The base14ahas a substantially disc shape and is made of a conductive material such as aluminum. A central axis of the base14asubstantially coincides with the axis Z. The base14ais supported by a cylindrical support48. The cylindrical support48is made of an insulating material and extends vertically upward from the bottom portion12b. A conductive cylindrical supporting portion50is provided at an outer periphery of the cylindrical support48. The cylindrical supporting portion50extends vertically upward from the bottom portion12bof the chamber main body12along the outer periphery of the cylindrical support48. An annular gas exhaust path51is formed between the cylindrical supporting portion50and the sidewall12a.

A baffle plate52is provided at an upper portion of the gas exhaust path51. The baffle plate52has an annular shape. The baffle plate52has a plurality of through-holes penetrating therethrough in a plate thickness direction. The above-described gas exhaust opening12his provided below the baffle plate52. A gas exhaust unit56is connected to the gas exhaust opening12hthrough a gas exhaust line54. The gas exhaust unit56includes an APC (Automatic Pressure Control) valve and a vacuum pump such as a turbo molecular pump. A pressure in the processing space S can be reduced to a desired vacuum level by the gas exhaust unit56.

The base14aserves as a high frequency electrode. A high frequency power supply58for RF bias is electrically connected to the base14athrough a power feed rod62and a matching unit60. The high frequency power supply58outputs a high frequency power having a frequency suitable for controlling energy of ions attracted to the target object WP, e.g., a high frequency of 13.65 MHz (hereinafter, referred to as “high frequency for bias”) at a preset power level. The matching unit60has therein a matcher for matching an impedance of the high frequency power supply58and an impedance of a load side, mainly an electrode, a plasma and the chamber main body12. The matcher includes a blocking capacitor for self-bias generation.

The electrostatic chuck14cis provided on a top surface of the base14a. The target object WP is attracted and held on the electrostatic chuck14cby an electrostatic attractive force. The electrostatic chuck14cincludes an electrode14dand insulating films14eand14f. Further, the electrostatic chuck14chas a substantially disc shape. The central axis of the electrostatic chuck14csubstantially coincides with the axis Z. The electrode14dof the electrostatic chuck14cis formed of a conductive film and provided between the insulating films14eand14f. A DC power supply64is electrically connected to the electrode14dthrough a switch66and a coated wire68. The electrostatic chuck14ccan attract and hold the target object WP by a Coulomb force generated by a DC voltage applied from the DC power supply64. A focus ring14bis provided on the base14a. The focus ring14bis disposed to surround the target object WP and the electrostatic chuck14c.

A coolant channel14gis provided in the base14a. The coolant channel14gextends about, e.g., the axis Z. A coolant from a chiller unit is supplied into the coolant channel14gthrough a line70. The coolant supplied into the coolant channel14greturns to the chiller unit through a line72. By controlling a temperature of the coolant by the chiller unit, a temperature of the electrostatic chuck14cand hence a temperature of the target object WP are controlled.

A gas supply line74is formed in the stage14. The gas supply line74is provided to supply a heat transfer gas, e.g., He gas, to a gap between a top surface of the electrostatic chuck14cand a backside of the target object WP.

The microwave output device16generates a microwave having a power corresponding to a set power. The microwave output device16outputs a microwave of a single frequency, i.e., a single peak SP, for exciting a processing gas supplied into the chamber main body12. The microwave output device16is configured to variably control the frequency and the power of the microwave. In one example, the microwave output device16can control the power of the microwave within a range from 0 W to 5000 W and the frequency of the microwave within a range from 2400 MHz to 2500 MHz.

The plasma processing apparatus1further includes a waveguide21, a tuner26, a resonance frequency control unit29, a mode transducer27and a coaxial waveguide28. The waveguide21and the coaxial waveguide28guide the microwave generated by the microwave output device16to the antenna18of the chamber main body12which will be described later. An output unit of the microwave output device16is connected to one end of the waveguide21. The other end of the waveguide21is connected to the mode transducer27. The waveguide21is, e.g., a rectangular waveguide. The waveguide21is provided with the tuner26. The tuner26has movable short-circuiting plates S1to S4. Each of the movable short-circuiting plates S1to S4is configured to control a protruding amount thereof into the inner space of the waveguide21. The tuner26controls protruding positions of the movable short-circuiting plates S1to S4with respect to a predetermined position as a reference position, thereby matching the impedance of the microwave output device16and the impedance of the load, e.g., the chamber main body12.

The resonance frequency control unit29is provided between the tuner26in the waveguide (the waveguide21and the coaxial waveguide28) and the antenna18to be described later. The resonance frequency control unit29has a stub that can be inserted into the inner space of the waveguide. The configuration of the resonance frequency control unit29will be described in detail later.

The mode transducer27converts a mode of the microwave from the waveguide21and supplies the microwave after the mode conversion to the coaxial waveguide28. The coaxial waveguide28includes an outer conductor28aand an inner conductor28b. The outer conductor28ahas a substantially cylindrical shape and a central axis thereof substantially coincides with the axis Z. The inner conductor28bhas a substantially cylindrical shape and extends inside the outer conductor28a. The central axis of the inner conductor28bsubstantially coincides with the axis Z. The coaxial waveguide28transmits the microwave from the mode transducer27to the antenna18.

The antenna18is provided on a surface20bopposite to the bottom surface20aof the dielectric window20. The antenna18includes a slot plate30, a dielectric plate32and a cooling jacket34.

The slot plate30is provided on the surface20bof the dielectric plate20. The slot plate30is made of a conductive metal and has a substantially disc shape. A central axis of the slot plate30substantially coincides with the axis Z. The slot plate30has a plurality of slot openings30a. In one example, the slot openings30aform a plurality of slot pairs. Each of the slot pairs has two elongated slot openings30aextending in directions intersecting each other. The slot pairs are arranged along one or more concentric circles about the axis Z. A through-hole30dthrough which a conduit36to be described later can penetrate is formed at a central portion of the slot plate30.

The dielectric plate32is provided on the slot plate30. The dielectric plate32is made of a dielectric material such as quartz and has a substantially disc shape. A central axis of the dielectric plate32substantially coincides with the axis Z. The cooling jacket34is provided on the dielectric plate32. The dielectric plate32is provided between the cooling jacket34and the slot plate30.

The cooling jacket34has a conductive surface. A flow path34ais formed in the cooling jacket34. The coolant is supplied to the flow path34a. The lower end of the outer conductor28ais electrically connected to an upper surface of the cooling jacket34. The lower end of the inner conductor28bis electrically connected to the slot plate30through openings formed in a central portion of the cooling jacket34and the dielectric plate32.

The microwave from the coaxial waveguide28propagates through the dielectric plate32and is supplied to the dielectric window20through the slot openings30a. The microwave supplied to the dielectric window20is introduced into the processing space S.

The conduit36penetrates through the bore of the inner conductor28bof the coaxial waveguide28. As described above, the through-hole30dthrough which the conduit36can penetrate is formed in the central portion of the slot plate30. The conduit36extends through the bore of the inner conductor28band is connected to a gas supply system38.

The gas supply system38supplies a processing gas for processing the target object WP to the conduit36. The gas supply system38may include a gas source38a, a valve38band a flow rate controller38c. The gas source38ais a source of the processing gas. The valve38bswitches start and stop of the supply of the processing gas from the gas source38a. The flow rate controller38cis, e.g., a mass flow controller, and controls a flow rate of the processing gas supplied from the gas source38a.

The plasma processing apparatus1may further include an ejector41. The ejector41supplies a gas from the conduit36to a through-hole20hformed in the dielectric window20. The gas supplied to the through-hole20hof the dielectric window20is supplied to the processing space S. The processing gas is excited by the microwave introduced into the processing space S through the dielectric window20. Accordingly, a plasma is generated in the processing space S and the target object WP is processed by active species such as ions and/or radicals from the plasma.

The plasma processing apparatus1further includes a controller100. The controller100integrally controls the respective components of the plasma processing apparatus1. The controller100may include a processor such as a CPU, a user interface, and a storage unit.

The processor executes a process recipe and a program stored in the storage unit to integrally control the respective components such as the microwave output device16, the stage14, the gas supply system38, the gas exhaust unit56and the like. Further, the processor stores various measurement values and the like in the storage unit.

The user interface includes a keyboard or a touch panel through which a process manager inputs a command to manage the plasma processing apparatus1, a display for visualizing and displaying an operation state of the plasma processing apparatus1, and the like.

The storage unit stores a control program (software) for realizing various processes performed in the plasma processing apparatus1under the control of the processor, a process recipe including processing condition data and the like. The processor retrieves various control programs from the storage unit, if necessary, in response to an instruction from the user interface or the like, and executes the retrieved programs. A desired process is performed in the plasma processing apparatus1under the control of the processor. The storage unit may store a monitoring result in association with the executed process recipe (process condition). The monitoring result includes the tuner position and measurement values (to be described later) measured by the microwave output device16, and the like.

Hereinafter, the microwave output device16, the tuner and the resonance frequency control unit29will be described in detail.FIG. 2shows the microwave output device16, the tuner26and the resonance frequency control unit29. The microwave output device16includes a microwave generation unit16a, a waveguide16b, a circulator16c, waveguides16dand16e, a first directional coupler16f, a first measurement unit16g, a second directional coupler16h, a second measurement unit16i, and a dummy load16j.

The microwave generation unit16aincludes a waveform generation unit161, a power control unit162, an attenuator163, amplifiers164and165, and a mode transducer166. The waveform generation unit161generates a microwave. The waveform generation unit161is connected to the controller100and the power control unit162. The waveform generation unit161generates a single peak microwave having a frequency corresponding to a set frequency specified by the controller100. The waveform generation unit161has, e.g., a PLL (Phase Locked Loop) oscillator for generating a single peak microwave having a frequency corresponding to the set frequency.

The output of the waveform generation unit161is connected to the attenuator163. The power control unit162is connected to the attenuator163. The power control unit162may be, e.g., a processor. The power control unit162controls an attenuation rate of the microwave in the attenuator163such that the microwave having a power corresponding to a set power specified by the controller100is outputted from the microwave output device16. The output of the attenuator163is connected to the mode transducer166through the amplifiers164and165. The amplifiers164and165are configured to amplify the microwave at respective amplification factors. The mode transducer166is configured to convert a mode of the microwave outputted from the amplifier165. The microwave generated by the mode conversion in the mode transducer166is outputted as an output microwave of the microwave generation unit16a.

The output of the microwave generation unit16ais connected to one end of the waveguide16b. The other end of the waveguide16bis connected to a first port261of the circulator16c. The circulator16cincludes the first port261, a second port262and a third port263. The circulator16cis configured to output a microwave inputted into the first port261from the second port262and output a microwave inputted into the second port262from the third port263. One end of the waveguide16dis connected to the second port262of the circulator16c. The other end of the waveguide16dserves as an output unit16tof the microwave output device16.

One end of the waveguide16eis connected to the third port263of the circulator16c. The other end of the waveguide16eis connected to the dummy load16j. The dummy load16jis configured to receive and absorb a microwave propagating through the waveguide16e. The dummy load16jconverts the microwave into heat, for example.

The first and the second directional coupler16fand16hare provided between one end and the other end of the waveguide16d. The first directional coupler16fis configured to branch a part of the microwave (i.e., traveling wave) outputted from the microwave generation unit16aand propagating to the output unit16tand output the part of the traveling wave. The first measurement unit16gdetermines a first measurement value indicating a power of the traveling wave in the output unit16tbased on the part of the traveling wave outputted from the first directional coupler16f.

The second directional coupler16his configured to branch a part of the microwave (i.e., reflection wave) returning to the output unit16tand output the part of the reflection wave. The second measurement unit16idetermines a second measurement value indicating a power of the reflection wave (reflection wave power) in the output unit16tbased on the part of the reflection wave outputted from the second directional coupler16h.

The first and the second measurement unit16gand16iare connected to the power control unit162. The first measurement unit16goutputs the first measurement value to the power control unit162. The second measurement unit16ioutputs the second measurement value to the power control unit162. The power control unit162controls the attenuator163such that a difference between the first measurement value and the second measurement value, i.e., a load power, coincides with the set power specified by the controller100. If necessary, the power control unit162controls the waveform generation unit161.

The tuner26controls the protruding positions of the movable short-circuiting plates S1to S4based on a signal of the controller100to match an impedance of the microwave output device16side and an impedance of the antenna18side. The tuner26operates the movable short-circuiting plates S1to S4by an actuator and a driver circuit (both not shown). The protruding positions of the movable short-circuiting plates after the matching are referred to as tuner positions.

The resonance frequency control unit29includes a stub29a, a motor29band a motor driver29c. The stub29ais a member that can be inserted into the inner space of the waveguide. The stub29ais, e.g., a cylindrical rod-shaped member. The stub29amay be made of the same material as that of the waveguide or a metal. Such a material may be, e.g., bulk aluminum or bulk copper, or a metal alloy of brass or the like. The stub29amay have a surface coated with a metal such as copper, gold or the like. An insertion direction of the stub29amay be perpendicular to a traveling direction of the microwave. A protruding length of the stub29ainto the inner space of the waveguide is referred to as a stub insertion length. In other words, when one end of the stub29adoes not protrude into the inner space of the waveguide, the stub insertion length is zero. A motor29bis provided at the other end of the stub29a. The motor29bis driven by a motor driver29cand moves the stub29ainto the inner space of the waveguide. The motor driver29coperates based on a signal of the controller100.

FIGS. 3A and 3Bshow positions of the resonance frequency control unit29. The resonance frequency control unit29is provided between the antenna18and the tuner26in the waveguide. The resonance frequency control unit29may be provided in the waveguide21as can be seen fromFIG. 3Aor may be provided in the waveguide where the mode transducer27is disposed as can be seen fromFIG. 3B. Or, the resonance frequency control unit29may be provided in the coaxial waveguide28. The resonance frequency control unit29may be provided anywhere between the tuner26and the antenna18.

Next, characteristics of the resonance frequency control unit29of the plasma processing apparatus1were examined by simulation. The simulation was performed under the following condition: the resonance frequency control unit29was arranged to a position shown inFIG. 3A(13 mm from a concentric center of the coaxial waveguide28); a diameter of the stub was set to 20 mm; and a height of the inner space of the waveguide21was set to 27 mm. The relation between the resonance frequency and the reflection wave power was simulated on a stub insertion length basis. The relation between the resonance frequency and the reflection wave power was simulated while the stub insertion length was varied to 0 mm, 8 mm, 12 mm, 15 mm, 18 mm and 21 mm and an electron density ne was varied to 8.0×1010(1/cm3), 9.0×1010(1/cm3), 10×1010(1/cm3) and 20×1010(1/cm3).

FIG. 4Ashows a result of simulating the relation between the resonance frequency and the reflection wave power on a stub insertion basis at the electron density ne of 8.0×1010(1/cm3). The vertical axis indicates the reflection wave power [W] and the horizontal axis indicates the resonance frequency [Hz]. As can be seen fromFIG. 4A, as the stub insertion length is increased, the resonance frequency at which the reflection wave power becomes minimum is shifted to the left side.

FIG. 4Bshows a result of simulating the relation between the resonance frequency and the reflection wave power on a stub insertion basis at the electron density ne of 9.0×1010(1/cm3). The vertical axis indicates the reflection wave power [W] and the horizontal axis indicates the resonance frequency [Hz]. As can be seen fromFIG. 4B, as the stub insertion length is increased, the resonance frequency at which the reflection wave power becomes minimum is shifted to the left side.

FIG. 5Ashows a result of simulating the relation between the resonance frequency and the reflection wave power on a stub insertion basis at the electron density ne of 10×1010(1/cm3). The vertical axis indicates the reflection wave power [W] and the horizontal axis indicates the resonance frequency [Hz]. As can be seen fromFIG. 5A, as the stub insertion length is increased, the resonance frequency at which the reflection wave power becomes minimum is shifted to a right side.

FIG. 5Bshows a result of simulating the relation between the resonance frequency and the reflection wave power on a stub insertion basis at the electron density ne of 20×1010(1/cm3). The vertical axis indicates the reflection wave power [W] and the horizontal axis indicates the resonance frequency [Hz]. As can be seen fromFIG. 5B, as the stub insertion length is increased, the resonance frequency at which the reflection wave power becomes minimum is shifted to the right side.

FIG. 6Ais a graph in which the simulation result ofFIG. 4Ais expressed as the relation between the stub insertion length and the resonance frequency at which the reflection wave power becomes minimum. The vertical axis inFIG. 6Aindicates a resonance frequency [Hz] at which a reflection wave power becomes minimum with respect to a reference frequency at which a reflection wave power becomes minimum in the case of setting the stub insertion length to zero. In other words, the vertical axis indicates variation of the resonance frequency at which the reflection wave power becomes minimum in the case of setting the stub insertion length to zero. The horizontal axis inFIG. 6Aindicates the stub insertion length [mm]. As can be seen fromFIG. 6A, as the stub insertion length is increased within a range from 0 mm to 12 mm (indicated by a dotted line), the resonance frequency at which the reflection wave power becomes minimum is decreased (monotonous decrease).

FIG. 6Bis a graph in which the simulation result ofFIG. 4Bis expressed as the relation between the stub insertion length and the resonance frequency at which the reflection wave power becomes minimum. The vertical axis inFIG. 6Bindicates a resonance frequency [Hz] at which a reflection wave power becomes minimum with respect to a reference frequency at which a reflection wave power becomes minimum in the case of setting the stub insertion length to zero. In other words, the vertical axis indicates variation of the resonance frequency at which the reflection wave power becomes minimum in the case of setting the stub insertion length to zero. The horizontal axis inFIG. 6Bindicates the stub insertion length [mm]. As can be seen fromFIG. 6B, as the stub insertion length is increased within a range from 0 mm to 12 mm (indicated by a dotted line), the resonance frequency at which the reflection wave power becomes minimum is decreased (monotonous decrease).

FIG. 7Ais a graph in which the simulation result ofFIG. 5Ais expressed as the relation between the stub insertion length and the resonance frequency at which the reflection wave power becomes minimum. The vertical axis inFIG. 7Aindicates a resonance frequency [Hz] at which a reflection wave power becomes minimum with respect to a reference frequency at which a reflection wave power becomes minimum in the case of setting the stub insertion length to zero. In other words, the vertical axis indicates the variation of the resonance frequency at which the reflection wave power becomes minimum in the case of setting the stub insertion length to zero. The horizontal axis inFIG. 7Aindicates the stub insertion length [mm]. As can be seen fromFIG. 7A, as the stub insertion length is increased within a range from 0 mm to 12 mm (indicated by a dotted line), the resonance frequency at which the reflection wave power becomes minimum is increased (monotonous increase).

FIG. 7Bis a graph in which the simulation result ofFIG. 5Bis expressed as the relation between the stub insertion length and the resonance frequency at which the reflection wave power becomes minimum. The vertical axis inFIG. 7Bindicates a resonance frequency [Hz] at which a reflection wave power becomes minimum with respect to a reference frequency at which a reflection wave power becomes minimum in the case of setting the stub insertion length to zero. In other words, the vertical axis indicates the variation of the resonance frequency at which the reflection wave power becomes minimum in the case of setting the stub insertion length to zero. The horizontal axis inFIG. 7Bindicates the stub insertion length [mm]. As can be seen fromFIG. 7B, as the stub insertion length is increased within a range from 0 mm to 12 mm (indicated by a dotted line), the resonance frequency at which the reflection wave power becomes minimum is increased (monotonous increase).

As can be seen fromFIGS. 6A and 6B, at a low electron density (ne=8.0×1010(1/cm3) to 9.0×1010(1/cm3)), the resonance frequency at which the reflection wave power becomes minimum tends to be decreased as the stub insertion length is increased within a range from 0 mm to 12 mm. As can be seen fromFIGS. 7A and 7B, at a high electron density (ne=10×1010(1/cm3) to 20×1010(1/cm3)), the resonance frequency at which the reflection wave power becomes minimum tends to be increased as the stub insertion length is increased within a range from 0 mm to 12 mm.

Next, the relation between the reflection wave power and the stub insertion length was simulated. InFIG. 8showing the result of the simulation, the vertical axis indicates the reflection wave power [W] and the horizontal axis indicates the stub insertion length [mm]. The average of the reflection wave powers at the electron density ne of 8.0×1010(1/cm3), 9.0×1010(1/cm3), 10×1010(1/cm3) and 20×1010(1/cm3) was plotted. When the stub insertion length was within the range (0 mm to 12 mm) at which the monotonous decrease and the monotonous increase were monitored, the reflection wave power was about 10 W at most and within the tolerable range.

Next, a microwave control method using the characteristics of the resonance frequency control unit29which have been examined by the above-described simulations will be explained. In the microwave control method, an apparatus state at the time of initial introduction of the apparatus or at the time of completion of the maintenance such as exchange of the ceiling plate or the like is set to a reference apparatus state and compared with a current apparatus state. The resonance frequency control unit29operates when a change is detected as a result of comparison.

In the microwave control method, first, information of an apparatus as a reference is obtained.FIG. 9is a flowchart showing a process of obtaining an initial tuner position. The process of the flowchart shown inFIG. 9may be executed at the time of the initial introduction of the plasma processing apparatus1or at the time of completion of the maintenance of the apparatus1. The process of the flowchart is executed by the controller100.

As shown inFIG. 9, first, the controller100sets a stub insertion length and a frequency of a microwave in an initial setting process S10. For example, the controller100sets the stub insertion length to 0 [mm] and the frequency of the microwave to 2450 [MHz]. If a stub insertion length at the time of completion of a previous maintenance is stored in the storage unit, the controller100may use the stub insertion length stored in the storage unit. The frequency of the microwave has a fixed value.

Next, the controller100obtains a process condition in a process condition obtaining process S12. For example, the controller100obtains a process condition by reading out a process recipe stored in the storage unit.

Next, the controller100starts output of the microwave in a microwave output start process S14. For example, the controller100output the microwave based on the process condition obtained by the process condition obtaining process S12. At this time, the tuner26operates the movable short-circuiting plates S1to S4to perform impedance matching automatically. The controller100determines whether or not the impedance matching is completed in a determination process S16. For example, the controller100determines whether or not the positions of the movable short-circuiting plates are stable. The determination is repeated until the positions of the movable short-circuiting plates become stable. The stable positions of the movable short-circuiting plates indicate that the detected positions of the movable short-circuiting plates are within a range of ±0.1 mm for three seconds consecutively (sampling interval of, e.g., 0.1 sec). The process of the flowchart shown inFIG. 9may be completed by providing a threshold of timeout in consideration of the case in which the determination process S16is looped.

Upon completion of the impedance matching, in a storing process S18, the controller100stores, in the storage unit, the process condition obtained in the process condition obtaining process S12in association with the position (tuner position) of the movable short-circuiting plate after the impedance matching. For example, the controller100may manage ID of the process condition and the tuner position in the form of a table. In the storing process S18, the apparatus state at the time of completion of the maintenance (tuner position with respect to a predetermined process condition) is stored. The stored tuner position is an initial tuner position and serves as a reference for determining whether or not the resonance frequency control unit29needs to be operated. When the storing process S18is completed, the process of the flowchart shown inFIG. 9is completed.

The controller100performs the process of the flowchart shown inFIG. 9under the process conditions to be executed and stores the initial (reference) tuner position with respect to the respective process conditions.

Next, the controller100performs the process of the flowchart shown inFIG. 10as a microwave control method. The process of the flowchart shown inFIG. 10may be executed at predetermined timing after the execution of the process of the flowchart shown inFIG. 9.

As shown inFIG. 10, first, the controller100obtains a process condition in a process condition obtaining process S20. For example, the controller100obtains the process condition by reading out the process recipe stored in the storage unit. The controller100sets a frequency of a microwave based on the process condition.

Next, the controller100obtains an initial tuner position in a tuner position obtaining process S22. The controller100obtains the initial tuner position corresponding to the process condition obtained in the process condition obtaining process S20by referring to the storage unit.

Next, the controller100obtains a stub insertion length and a frequency of a microwave in a previous value obtaining process S24. As will be described later, the storage unit stores, as a history, the process condition in association with the stub insertion length and the frequency of the microwave used in the process condition. The controller100obtains the frequency of the microwave and the previous stub insertion length corresponding to the process condition obtained in the process condition obtaining process S20by referring to the storage unit. In case of the first execution, the previous stub insertion length and the frequency of the microwave do not exist as the history. Therefore, initial set values (e.g., a stub insertion length of 0 [mm], a frequency of 2450 [MHz]) are employed.

Next, in a microwave output start process S26, the controller100controls the stub29ato have the stub insertion length obtained in the previous value obtaining process S24and outputs the microwave at the frequency obtained in the previous value obtaining process S24. At this time, the tuner26operates the movable short-circuiting plates S1to S4to perform impedance matching automatically. The controller100determines whether or not the impedance matching is completed in a determination process S28. For example, the controller100determines whether or not the positions of the movable short-circuiting plates are stable. The determination is repeated until the positions of the movable short-circuiting plates become stable. The stable positions of the movable short-circuiting plates indicate that the detected positions of the movable short-circuiting plates are within a range of ±0.1 mm for three seconds consecutively (sampling interval of, e.g., 0.1 sec). The process of the flowchart shown inFIG. 10may be completed by providing a threshold of timeout in consideration of the case in which the determination process S28is looped.

Next, the controller100determines whether or not the stub insertion length is smaller than a threshold in a stub insertion length determination process S30. The threshold is used for determining a limit of the stub insertion length. For example, it is possible to employ a maximum value of 12 [mm] within a range of the stub insertion length (0 mm to 12 mm) which has been examined by the simulation.

When it is determined that the stub insertion length is smaller than the threshold, the controller100detects a current tuner position in a tuner position detection process S32(detection step). In other words, the controller100detects positions (tuner positions) of the movable short-circuiting plates S1to S4which have been controlled by the tuner26for the microwave outputted by the microwave output device16.

Next, the controller100determines a deviation of the tuner position from the reference position in a determination process S34(determination step). For example, the controller100calculates a difference between the current tuner position and the initial tuner position obtained in the tuner position obtaining process S22and determines whether or not the difference is within a tolerable range. For example, on the assumption that a tuner position of the movable short-circuiting plate S1is set to T1; an initial tuner position is set to TINI1; and a tolerable value is set to ΔX (e.g., ±1 mm), when a condition T1>TINI1+ΔX is satisfied, the controller100determines that the difference is not within the tolerable range. For example, on the assumption that a tuner position of the movable short-circuiting plate S3is set to T3; an initial tuner position is set to TINI3and a tolerable value is set to ΔY (e.g., ±1 mm), when a condition T3>TINI3+ΔY is satisfied, the controller100determines that the difference is not within the tolerable range. The controller100may determine either of the tuner position T1or T3. Alternatively, only when both of the tuner positions T1and T3are determined to be within the tolerable range, it may be determined that the tuner positions are within the tolerable range.

When it is determined that the current tuner position is within the tolerable range, in a storing process S36, the controller100stores in the storage unit the process condition obtained in the process condition obtaining process S20in association with a current stub insertion length and a frequency of the microwave. For example, the controller100may manage ID of the process condition and the current stub insertion length and the frequency of the microwave in the form of a table. In the storing process S36, a current apparatus state is stored. The stored tuner position is utilized as a previous value in a next process. When the storing process S36is completed, the process of the flowchart shown inFIG. 10is completed.

On the other hand, when it is determined in the determination process S34that the current tuner position is not within the tolerable range, the controller100controls the stub insertion length of the stub29ain a stub insertion process S38(control step). For example, the controller100inserts the stub29ain the inner space of the waveguide21by a predetermined length. For example, the controller100inserts the stub29ainto the inner space of the waveguide21by 0.1 mm. Since the stub29ais inserted, the resonance frequency needs to be increased. Therefore, in the process of the flowchart, a high electron density (ne=10×1010(1/cm3) to 20×1010(1/cm3)) is required as examined in the simulation. Thereafter, the determination process S28, the stub insertion length determination process S30, the tuner position detection process S32and the determination process S34are executed in that order. The controller100repeatedly executes the determination process S28, the stub insertion length determination process S30, the tuner position detection process S32and the determination process S34until it is determined in the determination process S24that the difference between the reference position and the position of the movable short-circuiting plate is within the tolerable range. By controlling the stub insertion length as described above, the resonance frequency can be changed and the tuner position can be within the tolerable range.

When it is determined in the stub insertion length determination process S30that the stub insertion length is not smaller than the threshold, the controller100changes the stub insertion length to a threshold in a stub insertion length fixing process S40. This threshold is the same as the threshold used in the stub insertion length determination process S30. Here, the threshold is 12 mm.

Next, the controller100changes the frequency of the microwave generated by the microwave output device16in a frequency change process S42(change step). Then, the above-described determination process S28is performed. As such, when the control using the stub29ahas limitation, it is possible to control the reflection wave power to be within the tolerable range by employing another approach for changing the frequency of the microwave.

In the microwave control method of the present embodiment, when the difference between the reference position and the positions of the movable short-circuiting plates S1to S4is not within the tolerable range, the insertion length of the stub29aprovided between the tuner26and the antenna18(length of insertion into the inner space of the waveguide) is controlled. In other words, when the tuner position is deviated from the tolerable range due to the consumption of the ceiling plate, the insertion length of the stub is controlled. Accordingly, the resonance frequency between the tuner26and the plasma may be deviated, which makes it possible to avoid generation of an unstable plasma. Therefore, even when a temporal change such as the consumption of the ceiling plate or the like occurs, the availability of the plasma processing apparatus1can be improved.

Second Embodiment

A microwave control method according to a second embodiment is the same as the microwave control method according to the first embodiment except that the difference between the current reflection wave power and the initial reflection wave power is determined instead of the difference between the current tuner position and the initial tuner position and also in that the resonance frequency control unit29is driven when a change is detected. Therefore, description of the same features will be omitted.

A plasma processing apparatus to which the microwave control method according to the second embodiment is applied is the same as the plasma processing apparatus1.

In the microwave control method according to the second embodiment, as in the microwave control method according to the first embodiment, an apparatus state at the time of initial introduction of an apparatus or at the time of completion of the maintenance such as exchange of the ceiling plate or the like is set to a reference apparatus state and compared with a current apparatus state. The resonance frequency control unit29operates when a change is detected as a result of comparison.

FIG. 11is a flowchart showing a process of obtaining an initial reflection wave power. The process of the flowchart shown inFIG. 11may be executed at the time of the initial introduction of the plasma processing apparatus1or at the time of completion of the maintenance for the apparatus1, as in the case of the process of the flowchart shown inFIG. 9. The process of the flowchart is executed by the controller100.

An initial setting process S50, a process condition obtaining process S52and a microwave output start process S54shown inFIG. 11are the same as the initial setting process S10, the process condition obtaining process S12and the microwave output start process S14shown inFIG. 9.

The controller100determines whether or not the impedance matching is completed in a determination process S56. For example, the controller100determines whether or not the reflection wave power is stable. The determination is repeated until the reflection wave power becomes stable. The stable reflection wave power indicates that the detected reflection wave power is within a range of ±1 W for three seconds consecutively (sampling interval of, e.g., 0.1 sec). The process of the flowchart shown inFIG. 11may be completed by providing a threshold of timeout in consideration of the case in which the determination process S16is looped.

Upon completion of the impedance matching, in a storing process S58, the controller100stores, in the storage unit, the process condition obtained in the process condition obtaining process S52in association with the reflection wave power after the impedance matching. For example, the controller100may manage ID of the process condition and the reflection wave power in the form of a table. In the storing process S58, the apparatus state at the time of completion of the maintenance (reflection wave power with respect to a predetermined process condition) is stored. The stored reflection wave power is an initial reflection wave power and serves as a reference (reference reflection wave power) for determining whether or not the resonance frequency control unit29operates. When the storing process S58is completed, the process of the flowchart shown inFIG. 11is completed.

The controller100executes the process of the flowchart shown inFIG. 11under process conditions to be executed and stores the initial (reference) reflection wave power with respect to the respective process conditions.

Next, the controller100performs the process of the flowchart shown inFIG. 12as a microwave control method. The process of the flowchart shown inFIG. 12may be executed at predetermined timing after the execution of the process of the flowchart shown inFIG. 11.

First, the controller100performs a process condition obtaining process S60. The process condition obtaining process S60is the same as the process condition obtaining process S20shown inFIG. 10.

Next, the controller100obtains an initial reflection wave power in a reflection wave power obtaining process S62. The controller100obtains an initial reflection wave power corresponding to the process condition obtained in the process condition obtaining process S60while referring to the storage unit.

Then, the controller100performs a previous value obtaining process S64and a microwave output start process S66. The previous value obtaining process S64and the microwave output start process S66are the same as the previous value obtaining process S24and the microwave output start process S26shown inFIG. 10.

Thereafter, the controller100determines whether or not the impedance matching is completed in a determination process S68. For example, the controller100determines whether or not the reflection wave power is stable. The determination is repeated until the reflection wave power becomes stable. The process of the flowchart shown inFIG. 12may be completed by providing a threshold of timeout in consideration of the case in which the determination process S68is looped.

Next, the controller100executes a stub insertion length determination process S70. The stub insertion length determination process S70is the same as the stub insertion length determination process S30shown inFIG. 10.

When it is determined that the stub insertion length is smaller than a threshold, the controller100detects a current reflection wave power in a reflection wave power detection process S72(detection step). In other words, the controller100detects a reflection wave power for the microwave outputted by the microwave output device16.

Next, the controller100determines a deviation from a reference reflection wave power in a determination process S74(determination step). For example, the controller100calculates a difference between the current reflection wave power and the initial reflection wave power obtained in the reflection wave power obtaining process S62and determines whether or not the difference is within a tolerable range. For example, on the assumption that a reflection wave power is set to Pr; an initial reflection wave power is set to PINI1; and a tolerable value is set to ΔPr (e.g., +10 W), when a condition Pr>PINI1+ΔPr is satisfied, the controller100determines that the difference is not within the tolerable range.

When it is determined that the current reflection wave power is within the tolerable range, in a storing process S76, the controller100stores in the storage unit the process condition obtained in the process condition obtaining process S20in association with a current stub insertion length and a frequency of the microwave. For example, the controller100may manage ID of the process condition and the current stub insertion length and the frequency of the microwave in the form of a table. In the storing process S76, a current apparatus state is stored. The stored tuner position is utilized as a previous value in a next process. When the storing process S76is completed, the process of the flowchart shown inFIG. 12is completed.

On the other hand, when it is determined in the determination process S74that the current reflection wave power is not within the tolerable range, the controller100controls the stub insertion length of the stub29ain a stub insertion process S78(control step). The stub insertion process S78is the same as the stub insertion process S38shown inFIG. 10. Thereafter, the determination process S68, the stub insertion length determination process S70, the reflection wave power detection process S72and the determination process S74are executed in that order. The controller100repeatedly executes the determination process S68, the stub insertion length determination process S70, the reflection wave power detection process S72and the determination process S74until it is determined in the determination process S74that the difference between the reference reflection wave power and the current reflection wave power is within the tolerable range. By controlling the stub insertion length as described above, the resonance frequency can be changed and the reflection wave power can be within the tolerable range.

When it is determined in the stub insertion length determination process S70that the stub insertion length is not smaller than the threshold, the controller100changes the stub insertion length to a threshold in a stub insertion length fixing process S80. This threshold is the same as the threshold used in the stub insertion length determination process S70. In this case, the threshold is 12 mm.

Next, the controller100changes the frequency of the microwave generated by the microwave output device16in a frequency change process S82(change step). Then, the above-described determination process S68is performed. When the control using the stub29ahas limitation, it is possible to control the reflection wave power to be within the tolerable range by employing another approach for changing the frequency of the microwave.

In the microwave control method of the present embodiment, when the difference between the reference reflection wave power and the current reflection wave power is not within the tolerable range, the insertion length of the stub29aprovided between the tuner26and the antenna18(length of insertion into the inner space of the waveguide) is controlled. In other words, when the reflection wave power is deviated from the tolerable range due to the consumption of the ceiling plate, the insertion length of the stub is controlled. Accordingly, the resonance frequency between the tuner26and the plasma may be deviated, which makes it possible to avoid generation of an unstable plasma. Therefore, the availability of the plasma processing apparatus1can be improved.

Third Embodiment

A microwave control method according to a third embodiment is the same as the microwave control method according to the first embodiment except that an alarm process is performed instead of the frequency change process S42. Therefore, the same features as those of the microwave control method according to the first embodiment will be omitted.

The frequency change process S42is not performed when there is an operational demand and when there is a mechanical restriction. The operational demand includes a case in which the frequency of the microwave is fixed in consideration of an effect of reproducibility or the like. In that case, it is not appropriate to perform the frequency changing process S42described in the first embodiment. The mechanical restriction includes a case in which a magnetron is employed as the microwave output device16. In that case, the frequency of the microwave is resultantly determined and, thus, the frequency changing process S42cannot be performed.FIG. 13shows the microwave output device16A, the tuner26and the resonance frequency control unit29to which the microwave control method according to the third embodiment is applied. As shown inFIG. 13, the microwave output device16A includes a magnetron16xand a controller110xfor controlling the magnetron16x. A plasma processing apparatus to which the microwave control method according to the third embodiment is applied is the same as the plasma processing apparatus1except in the configuration of the microwave output device in case that there is a structural restriction. In view of an operational demand, the configuration of the apparatus is not different.

In the microwave control method according to the third embodiment, as in the microwave control method according to the first embodiment, an apparatus state at the time of initial introduction of the apparatus or at the time of completion of the maintenance such as exchange of ceiling plate or the like is set to a reference apparatus state and compared with a current apparatus state. The resonance frequency control unit29operates when a change is detected as a result of comparison.

In the microwave control method, first, information on an apparatus as a reference is obtained.FIG. 14is a flowchart showing a process of for obtaining an initial tuner position. The process of the flowchart shown inFIG. 14may be executed at the time of the initial introduction of the plasma processing apparatus1or at the time of completion of the maintenance for the apparatus1. The process of the flowchart is executed by a controller100x.

As shown inFIG. 14, first, the controller100xsets a stub insertion length in an initial setting process S110. The initial setting process S110is the same as the initial setting process S10shown inFIG. 9except that the frequency of the microwave is not set.

The process condition obtaining process S112, the microwave output start process S114, the determination process S116and the storing process S118shown inFIG. 14are the same as the process condition obtaining process S12, the microwave output start process S14, the determination process S16and the storing process S18shown inFIG. 9. In this manner, the process of the flowchart shown inFIG. 14is completed.

The controller100xperforms the process of the flowchart shown inFIG. 14under the process conditions to be executed and stores an initial (reference) tuner position with respect to the respective process conditions.

Next, the controller100xperforms the process of the flowchart shown inFIG. 15as a microwave control method. The process of the flowchart shown inFIG. 15may be executed at predetermined timing after the execution of the process of the flowchart shown inFIG. 14.

A process condition obtaining process S120and a tuner position obtaining process S122shown inFIG. 15are the same as the process condition obtaining process S20and the tuner position obtaining process S22shown inFIG. 10.

Then, the controller100xobtains a stub insertion length in a previous value obtaining process S124. The previous value obtaining process S124is the same as the previous value obtaining process S24shown inFIG. 10except that the frequency of the microwave is not set.

A microwave output start process S126, a determination process S128, a stub length insertion length determination process S130, a tuner position detection process S132(detection step), a determination process S134(determination step) and a stub insertion process S138(control step) are the same as the microwave output start process S26, the determination process S28, the stub insertion length determination process S30, the tuner position detection process S32(detection step), the determination process S34(determination step) and the stub insertion process S38(control step) shown inFIG. 10.

When it is determined that the current tuner position is within the tolerable range, in a storing process S136, the controller100xstores, in the storage unit, a current stub insertion length in association with the process condition obtained in the process condition obtaining process S120. The storing process S139is the same as the storing process S36shown inFIG. 10except that the frequency of the microwave is not set.

When it is determined in the stub insertion length determination process S130that the stub insertion length is not smaller than a threshold, the controller100xdisplays alarm information on the user interface or outputs the alarm information as sound in an alarm process S144. When the control using the stub has limitation, the maintenance operation can be promoted by outputting the alarm. Upon completion of the alarm process, the process of the flowchart shown inFIG. 15is completed.

Fourth Embodiment

A microwave control method according to a fourth embodiment is the same as the microwave control method according to the second embodiment except that the alarm process is performed instead of the frequency change process S82. Therefore, description of the same features as those of the microwave control method according to the second embodiment will be omitted. The frequency change process S82is not executed for the same reason as that described in the third embodiment. In other words, the configuration of the apparatus is the same as that described in the third embodiment.

In the microwave control method according to the fourth embodiment, as in the microwave control method according to the second embodiment, an apparatus state at the time of initial introduction of an apparatus or at the time of completion of the maintenance such as exchange of the ceiling plate or the like is set to a reference apparatus state and compared with a current apparatus state. The resonance frequency control unit29operates when a change is detected as a result of comparison.

FIG. 16is a flowchart showing a process of obtaining an initial reflection wave power. As in the case of the process of the flowchart shown inFIG. 11, the process of the flowchart shown inFIG. 16may be executed at the time of the initial introduction of the plasma processing apparatus1or at the time of completion of the maintenance for the apparatus1. The process of the flowchart is executed by the controller100x.

As shown inFIG. 16, first, the controller100xsets a stub insertion length in an initial setting process S150. The initial setting process S50is the same as the initial setting process S50shown inFIG. 11except that the frequency of the microwave is not set.

A process condition obtaining process S152, a microwave output start process S154, a determination process S156and a storing process S158shown inFIG. 16are the same as the process condition obtaining process S52, the microwave output start process S54, the determination process S56and the storing process S58shown inFIG. 11. In this manner, the process of the flowchart shown inFIG. 16is completed.

The controller100xexecutes the process of the flowchart shown inFIG. 16under process conditions to be executed and stores the initial (reference) reflection wave power with respect to the respective process conditions.

Next, the controller100performs the process of the flowchart shown inFIG. 17as a microwave control method. The process of the flowchart shown inFIG. 17may be executed at predetermined timing after the execution of the process of the flowchart shown inFIG. 16.

A process condition obtaining process S160and a reflection wave power obtaining process S162shown inFIG. 17are the same as the process condition obtaining process S20and the reflection wave power obtaining process S62shown inFIG. 12.

Next, the controller100xobtains a stub insertion length in a previous value obtaining process S164. The previous value obtaining process S164is the same as the previous value obtaining process S64shown inFIG. 12except that the frequency of the microwave is not set.

A microwave output start process S166, a determination process S168, a stub insertion length determination process S170, a reflection wave power detection process S172(detection step), a determination process S174(determination step) and a stub insertion process S178(control step) are the same as the microwave output start process S66, the determination process S68, the stub insertion length determination process S70, the reflection wave power detection process S72(detection step), the determination process S74(determination step) and the stub insertion process S78(control step) shown inFIG. 12.

When it is determined that the current reflection wave power is within the tolerable range, in the storing process S176, the controller100xstores, in the storage unit, a current stub insertion length in association with the process condition obtained in the process condition obtaining process S160. The storing process S176is the same as the storing process S76shown inFIG. 12except that the frequency of the microwave is not set.

On the other hand, when it is determined in the stub insertion length determination process S170that the stub insertion length is not smaller than a threshold value, the controller100xdisplays alarm information on the user interface or outputs the alarm information as sound in an alarm process S184. As such, when the control using the stub has limitation, the maintenance operation can be promoted by outputting the alarm. Upon completion of the alarm process, the process of the flowchart shown inFIG. 15is completed.

While various embodiments have been described, the present disclosure may be variously modified without being limited to the above-described embodiments. For example, the respective embodiments may be combined. For example, although the case in which the insertion length is controlled to a positive side has been described in the above embodiments, the insertion length may be controlled to a negative side. Such control may be appropriately changed based on the characteristics (monotonous decrease and monotonous increase) examined by the simulation. The stub may be replaced with the movable short-circuiting plate. The movable short-circuiting plate may be replaced with the stub.

While the disclosure has been shown and described with respect to the embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the disclosure as defined in the following claims.