Patent Publication Number: US-2022230856-A1

Title: Plasma processing system and plasma processing method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2021-007413, filed on Jan. 20, 2021, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a plasma processing system and a plasma processing method. 
     BACKGROUND 
     A plasma processing apparatus for performing plasma processing by placing a substrate on a stage provided inside a processing chamber is known. In a plasma processing apparatus, a consumable member that is gradually consumed by repeating plasma processing is present (for example, refer to Japanese Patent Application Publication No. 2018-10992). Examples of the consumable member include a focus ring (edge ring) provided around the substrate on an upper surface of the stage. Since the edge ring is reduced due to exposure to plasma, it is necessary to periodically replace the edge ring. 
     SUMMARY 
     The present disclosure provides a technique capable of detecting a state of a consumable member.  
     According to an aspect of the present disclosure, there is provided a plasma processing system for performing plasma processing on a substrate, the plasma processing system including: a chamber to which a consumable member is attached inside; a vacuum transfer chamber connected to the chamber; a transfer device provided in the vacuum transfer chamber and configured to transfer the consumable member between the chamber and the transfer device; a measuring instrument, provided outside the chamber in the plasma processing system and configured to detect a state of the consumable member; and a controller configured to control each element of the plasma processing system. 
     According to the present disclosure, it is possible to detect the state of the consumable member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view illustrating an example of a plasma processing system of a first embodiment. 
         FIG. 2  is a diagram illustrating an example of a hardware configuration of the plasma processing system of the first embodiment. 
         FIG. 3  is a view illustrating an example of a thickness detection sensor. 
         FIG. 4  is a vertical sectional view illustrating an example of a plasma processing apparatus of an embodiment. 
         FIG. 5  is a view for describing a raising/lowering pin  for raising or lowering an edge ring. 
         FIG. 6  is a view for describing a heat transfer gas supplied to a rear surface of the edge ring. 
         FIG. 7  is a view for describing a direct-current (DC) power source for applying a DC voltage to the edge ring. 
         FIG. 8  is a view for describing a multi-zone heater. 
         FIG. 9  is a flowchart illustrating an example of a transfer method of a first embodiment. 
         FIG. 10  is a flowchart illustrating another example of the transfer method of the first embodiment. 
         FIG. 11  is a view illustrating an example of a plasma processing system of a second embodiment. 
         FIG. 12  is a view illustrating an example of a plasma processing system of a third embodiment. 
         FIG. 13  is a view illustrating an example of a plasma processing system of a fourth embodiment. 
         FIG. 14  is a view illustrating an example of a plasma processing system of a fifth embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, non-limiting exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. In the drawings, the same or corresponding members or components are denoted by the same or corresponding reference symbols, and overlapping descriptions thereof will be omitted.  
     First Embodiment 
     Plasma Processing System 
     An example of a plasma processing system of a first embodiment will be described with reference to  FIGS. 1 to 3 . A plasma processing system PS 1  of the first embodiment is a system capable of performing various types of processing such as plasma processing on a substrate. 
     The plasma processing system PS 1  includes a vacuum transfer chamber TM, process modules PM 1  to PM 4 , load-lock chambers LL 1  and LL 2 , an atmospheric transfer chamber LM, a controller CU, and the like. 
     The vacuum transfer chamber TM has a substantially pentagonal shape in a plan view. In the vacuum transfer chamber TM, the process modules PM 1  to PM 4  are connected to two opposite side surfaces. The load-lock chambers LL 1  and LL 2  are connected to one side surface of the other two opposite side surfaces of the vacuum transfer chamber TM, and the thickness detection sensor S 11  and a position detection sensor S 12  are provided in the vicinity of the other side surface. The vacuum transfer chamber TM has a vacuum, chamber, and a transfer robot TR is disposed inside the chamber. 
     The transfer robot TR is configured to be rotatable, extensible, and movable vertically. The transfer robot TR places a transfer target object on a fork FK disposed at a distal end and transfers the transfer target object between the load-lock chambers LL 1  and LL 2  and the process modules  PM 1  to PM 4 . The transfer target object includes a substrate and a consumable member. The substrate may be, for example, a semiconductor wafer. The consumable member is a member that is attached in the process nodules PM 1  to FM 4  in a replaceable manner, and is consumed when various types of processing such as plasma processing are performed in the process modules PM 1  to PM 4 . The consumable member includes, for example, an edge ring FR, a cover ring, and a top plate of an upper electrode. The edge ring FR is an annular member disposed around the substrate in the process modules PM 1  to PM 4 . The cover ring is an annular member placed on an outer periphery of the edge ring FR and formed of quartz or the like. The top plate of the upper electrode is a plate-shaped member in which a plurality of gas introduction ports (not illustrated) are formed. 
     For example, as illustrated in  FIG. 3 , the thickness detection sensor S 11  detects a signal (for example, reflected light) from the edge ring FR when light L is projected onto the edge ring FR. Further, the thickness detection sensor S 11  transmits a detection signal to a thickness controller CT 11 . The thickness detection sensor S 11  may be provided inside the vacuum transfer chamber TM or may be provided outside the vacuum transfer chamber TM. The thickness detection sensor S 11  is a non-contact sensor, and may be, for example, a spectral interference type thickness sensor or a displacement sensor. Examples of the spectral interference type thickness  sensor include a wavelength sweep type interferometer and a multichannel spectral interferometer. Examples of the displacement sensor include a triangulation type (PSD type, CMOS type, CCD type) sensor, a coaxial confocal type sensor, a white coaxial confocal type sensor, and a photo-cutting type sensor. In the example of  FIG. 3 , a case where the thickness detection sensor S 11  detects the thickness of the edge ring FR from above the edge ring FR has been described. However, the present disclosure is not limited thereto. For example, the thickness detection sensor S 11  may be configured to detect the thickness of the edge ring FR from below the edge ring FR. Further, for example, the thickness detection sensor S 11  may be configured to detect the thickness of the edge ring FR from both sides (upper and lower) of the edge ring FR. The detection of the thickness of the edge ring FR from both sides of the edge ring FR may increase accuracy of the detected thickness of the edge ring FR. 
     The thickness controller CT 11  calculates the thickness of the edge ring FR based on the detection signal from the thickness detection sensor S 11 . The thickness controller CT 11  outputs the calculated thickness of the edge ring FR to the controller CU. 
     The position detection sensor S 12  detects the position of the transfer target object held by the fork FK, and transmits a detection signal to the position controller CT 12 . The position detection sensor S 12  detects the position of the  substrate held by the fork FK, for example, by detecting a plurality of locations on an outer peripheral portion of the substrate. Further, for example, the position detection sensor S 12  detects the positions of the edge ring FR held by the fork FK by detecting a plurality of positions of an inner peripheral portion of the edge ring FR. 
     The position controller CT 12  calculates a misalignment amount of the transfer target, object from a reference position based on the position of the transfer target object detected by the position detection sensor S 12  and a predetermined reference position, and transmits the calculated misalignment amount to the controller CU. The controller CU controls the transfer robot TR so that the transfer target object is placed on a stage of a transfer destination (for example, the process modules PM 1  to PM 4 ) to correct the calculated misalignment amount. 
     The process modules PM 1  to FM 4  each have a processing chamber and have a stage disposed inside the chamber. After the substrate is placed on the stage, the process modules PM 1  to PM 4  each are decompressed interiorly to introduce a processing gas thereinto, an RF power is applied to generate plasma, and plasma processing is performed on the substrate by the generated plasma. Examples of the plasma processing include an etching process. The vacuum transfer chamber TM and the process modules PM 1  to PM 4  are separated by openable/closable gate valves G 1 .  
     The load-lock chambers LL 1  and LL 2  are disposed between the vacuum transfer chamber TM and the atmospheric transfer chamber LM. Each of the load-lock chambers LL 1  and LL 2  has an internal pressure variable chamber of which the inside can be switched between vacuum and atmospheric pressure. Here, the vacuum refers to a low-pressure state in which the pressure is reduced below the atmospheric pressure. The load-lock chambers LL 1  and LL 2  each have a stage disposed inside. When the substrate is loaded from the atmospheric transfer chamber LM into the vacuum transfer chamber TM, the load-lock chambers LL 1  and LL 2  each receive the substrate from the atmospheric transfer chamber LM while maintaining the inside at the atmospheric pressure, switch the inside to vacuum, and load the substrate into the vacuum transfer chamber TM. When the substrate is unloaded from the vacuum transfer chamber TM into the atmospheric transfer chamber LM, the load-lock chambers LL 1  and LL 2  each receive the substrate from the vacuum transfer chamber TM while maintaining the vacuum in the inside thereof, and load the substrate into the atmospheric transfer chamber LM while raising the internal pressure to the atmospheric pressure. The load-lock chambers LL 1  and LL 2  and the vacuum transfer chamber TM are separated by openable/closable gate valves G 2 . The load-lock chambers LL 1  and LL 2  and the atmospheric transfer chamber LM are separated by openable/closable gate valves G 3 . 
     The atmospheric transfer chamber LM is disposed to face  the vacuum transfer chamber TM. The atmospheric transfer chamber LM may be, for example, an equipment front end module (EFEM). The atmospheric transfer chamber LM has a rectangular parallelepiped shape and includes an FFU (Fan Filter Unit), and is an atmospheric transfer chamber maintained at an atmospheric pressure. Two load-lock chambers LL 1  and LL 2  are connected to one side surface of the atmospheric transfer chamber LM in a longitudinal direction. Load ports LP 1  to LP 3  are connected to the other side surfaces of the atmospheric transfer chamber LM in the Longitudinal direction. Containers for accommodating transfer target objects are placed in the load ports LP 1  to LP 3 . The container includes, for example, a container that accommodates one or more substrates and a container that accommodates one or more consumable members. The container accommodating the substrate may be, for example, a front-opening unified pod (FOUP). The container that accommodates the consumable member includes, for example, a container that accommodates the edge ring FR, a container that accommodates the cover ring, and a container that accommodates the top plate of the upper electrode. A transfer robot (not illustrated) is disposed in the atmospheric transfer chamber LM. The transfer robot transfers a transfer target object between the containers placed at the load ports LP 1  to LP 3  and the internal pressure variable chambers of the load-lock chambers LL 1  and LL 2 . The example of  FIG. 1  illustrates a case that the container accommodating the edge ring FR is placed  at the load port LP 3 . 
     The controller CU controls each part of the plasma processing system PS 1 , for example, the transfer robot TR provided in the vacuum transfer chamber TM, the transfer robot provided in the atmospheric transfer chamber LM, and the gate valves G 1  to G 3 . Further, the controller CU controls each part of the plasma processing system PS 1  to execute a measurement method of an embodiment to be described later. The controller CU includes a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), an auxiliary storage device, and the like. The CPU operates based on a program stored in the ROM or the auxiliary storage device, and controls each part of the plasma processing system PS 1 . 
     Plasma Processing Apparatus 
     An example of a plasma processing apparatus used as the process modules PM 1  to PM 4  provided in the plasma processing system PS 1  of  FIG. 1  will be described with reference to  FIG. 4 . 
     A plasma processing apparatus  1  includes a plasma processing chamber  10 , a gas supply  20 , a power source  30 , and an exhaust system  40 . Further, the plasma processing apparatus  1  includes a substrate support  11  and a gas introduction unit. The gas introduction unit is configured to introduce at least one processing gas into the plasma processing chamber  10 . The gas introduction unit includes a shower head  13 . The substrate support  11  is disposed in the  plasma processing chamber  10 . The shower head  13  is disposed above the substrate support  11 . In one embodiment, the shower head  13  constitutes at least a portion of a ceiling of the plasma processing chamber  10 . The plasma processing chamber  10  has a plasma processing space  10   s  defined by the shower head  13 , a sidewall  10   a  of the plasma processing chamber  10 , and the substrate support  11 . The plasma processing chamber  10  has at least one gas supply port for supplying at least one processing gas into the plasma processing space  10   s,  arid at least one gas exhaust port for exhausting the gas from the plasma processing space. The sidewall  10   a  is grounded. The shower head  13  and the substrate support  11  are electrically insulated from a housing of the plasma processing chamber  10 . 
     The substrate support  11  includes a main body  111  and a ring assembly  112 . The main body  111  has a central region (substrate support surface)  111   a  for supporting the substrate (wafer) W, and an annular region (ring support surface)  111   b  for supporting the ring assembly  112 . The annular region  111   b  of the main body  111  surrounds the central region  111   a  of the main body  111  in a plan view. The substrate W is disposed on the central region  111   a  of the main body,  111  and the ring assembly  112  is disposed on the annular region  111   b  of the main body  111  to surround the substrate W on the central region  111   a  of the main body  111 . In one embodiment, the main body  111  includes a base and an electrostatic chuck. The base includes a conductive member. The conductive member of the  base functions as a lower electrode. The electrostatic chuck is disposed on the base. The upper surface of the electrostatic chuck has a substrate support surface  111   a.  The electrostatic chuck has, for example, a configuration in which an adsorption electrode  111   c  is interposed between insulators The ring assembly  112  includes one or more annular members. At least one of the one or more annular members is the edge ring FR. Although not illustrated, the substrate support  11  may include a temperature control module configured to adjust at least one of the electrostatic chuck, the ring assembly  112 , and the substrate to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path, or a combination thereof. A heat transfer fluid such as a coolant or a gas flows through the flow path. Further, the substrate support  11  may include a heat transfer gas supply configured to supply a heat transfer gas between the rear surface of the substrate W and the substrate support surface  111   a.    
     The shower head  13  is configured to introduce at least one processing gas from the gas supply  20  into the plasma processing space  10   s.  The shower head  13  has at least one gas supply port  13   a,  at least one gas diffusion chamber  13   b,  and a plurality of gas introduction ports  13   c.  The processing gas supplied to the gas supply port  13   a  passes through the gas diffusion chamber  13   b  and is introduced into the plasma processing space  10   s  from the plurality of gas introduction  ports  13   c.  Further, the shower head  13  includes a conductive member. The conductive member of the shower head  13  functions as an upper electrode. The gas introduction unit may include, in addition to the shower head  13 , one or more side gas injectors (SGI) that are attached to one or more openings formed in the sidewall  10   a.    
     The gas supply  20  may include at least one gas source  21  and at least one flow rate controller  22 . In one embodiment, the gas supply  20  is configured to supply at least one processing gas from the respective corresponding gas sources  21  to the shower head  13  via the respective corresponding flow rate controllers  22 . Each flow rate controller  22  may include, for example, a mass flow controller or a pressure-controlled flow rate controller. Further, the gas supply  20  may include one or more flow rate modulation devices that modulate or pulse flow rates of at least one processing gas. 
     The power source  30  includes an RF power source  31  coupled to plasma processing chamber  10  via at least one impedance matching circuit. The RF power source  31  is configured to supply at least one RF signal (RF power), such as the source RF signal and the bias RF signal, to the conductive member of the substrate support  11  and/or the conductive member of the shower head  13 . As a result, plasma is formed from at least one processing gas supplied into the plasma processing space  10   s.  Accordingly, the RF power source  31  may function as at least a portion of a plasma generator  configured to generate plasma from one or more processing gases in the plasma processing chamber  10 . Further, supplying of the bias RF signal to the conductive member of the substrate support  11  can generate a bias potential in the substrate W to draw an ion component in the formed plasma to the substrate W. 
     In one embodiment, the RF power source  31  includes a first RF generator  31   a  and a second RF generator  31   b.  The first RF generator  31   a  is coupled to the conductive member of the substrate support  11  and/or the conductive member of the shower head  13  via at least one impedance matching circuit, and configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 13 MHz to 150 MHz. In one embodiment, the first RF generator  31   a  may be configured to generate a plurality of source RF signals having different frequencies. The generated one or more source RF signals are supplied to the conductive member of the substrate support  11  and/or the conductive member of the shower head  13 . The second RF generator  31   b  is coupled to the conductive member of the substrate support  11  via at least one impedance matching circuit, and configured to generate a bias RF signal (bias RF power). In one embodiment, the bias RF signal has a lower frequency than the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 400 kHz to 13.56 MHz. In one embodiment, the second RF generator  31   b  may  be configured to generate a plurality of bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to the conductive member of the substrate support  11 . Further, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed. 
     Further, the power source  30  may include a DC power source  32  coupled to the plasma processing chamber  10 . The DC power source  32  includes a first DC generator  32   a  and a second DC generator  32   b.  In one embodiment, the first DC generator  32   a  is connected to the conductive member of the substrate support  11  and configured to generate a first DC signal. The generated first bias DC signal is applied to the conductive member of the substrate support  11 . In one embodiment, the first DC signal may be applied to another electrode, such as an electrode in an electrostatic chuck. In one embodiment, the second DC generator  32   b  is connected to the conductive member of the shower head  13  and configured to generate a second DC signal. The generated second DC signal is applied to the conductive member of the shower head  13 . In various embodiments, at least one of the first, and second DC signals may be pulsed. The first and second DC generators  32   a  and  32   b  may be provided in addition to the RF power source  31 , and the first DC generator  32   a  may be provided instead of the second RF generator  31   b.    
     The exhaust system  40  may be connected to, for example,  a gas exhaust port  10   e  disposed at a bottom portion of the plasma processing chamber  10 . The exhaust system  40  may include a pressure adjusting valve and a vacuum pump. The pressure in the plasma processing space  10   s  is adjusted by the pressure adjusting valve. The vacuum pump may include a turbo molecular pump, a dry pump, or a combination thereof. 
     Lifter 
     An example of a lifter for raising or lowering the edge ring FR in the plasma processing apparatus  1  will be described with reference to  FIG. 5 . 
     A lifter  50  raises or lowers the edge ring FR. The lifter  50  includes a raising/lowering pin  51 , an actuator  52 , and a sealing member  53 . 
     The raising/lowering pin  51  is inserted into a through-hole  111   h  extending through the main body  111  in the vertical direction immediately below the edge ring FR. A distal end (first end) of the raising/lowering pin  51  abuts on the bottom surface of the edge ring FR. A base end (second end) of the raising/lowering pin  51  is supported by an actuator  52  disposed outside the plasma processing chamber  10 . 
     The actuator  52  moves the raising/lowering pin  51  up and down to adjust a height position of the edge ring FR. 
     The sealing member  53  is provided between an inner wall of the through-hole  111   h  and the raising/lowering pin  51 . The sealing member  53  seals a space between the inner wall of the through-hole  111   h  and the raising/lowering pin  51  in an  airtight manner. The sealing member  53  may be, for example, an O-ring. 
     When the edge ring FR is unloaded, first, the raising/lowering pin  51  is moved up and down by the actuator  52  to adjust the height position of the edge ring FR. Subsequently, the gate valve G 1  is opened, and the fork FK enters below the edge ring FR in the plasma processing chamber  10 . Subsequently, the raising/lowering pin  51  is lowered no place the edge ring FR on the fork FK. 
     When the edge ring FR is loaded, first, the gate valve G 1  is opened, and the fork FK holding the edge ring FR enters the plasma processing chamber  10 . Subsequently, the edge ring FR on the fork FK is delivered onto the raising/lowering pin  51  by raising the raising/lowering pin  51  by the actuator  52 . 
     Adsorption Mechanism and Heat Transfer Gas Supply Mechanism 
     With reference to  FIG. 6 , an adsorption mechanism that adsorbs the edge ring FR in the plasma processing apparatus  1  and a heat transfer gas supply mechanism that supplies a heat transfer gas to the rear surface of the edge ring FR will be described by way of example. 
     The adsorption mechanism  60  includes direct-current (DC) power sources  61   a  and  61   b,  switches  62   a  and  62   b,  and electrode plates  63   a  and  63   b.  The adsorption mechanism  60  generates an electrostatic force such as a Coulomb force by the voltages applied from the DC power sources  61   a  and  61   b  to the electrode  plates  63   a  and  63   b,  and adsorbs the edge ring FR on the main body  111  by the electrostatic force.  FIG. 6  illustrates an example in which the electrode plate is a bipolar electrode. However, the electrode plate may be a unipolar electrode. 
     The heat transfer gas supply mechanism  70  includes a heat transfer gas supply source  71  and a gas supply line  72 . The heat transfer gas supply source  71  supplies the heat transfer gas to the gas supply line  72 . As the heat transfer gas, a gas having thermal conductivity, for example, helium (He) gas or the like is preferably used. One end of the gas supply line  72  is connected to the heat transfer gas supply source  71 , and the other end thereof communicates between the upper surface of the main body  111  and the bottom surface of the edge ring FR. The heat transfer gas supply mechanism  70  supplies a heat transfer gas from the heat transfer gas supply source  71  to a space between the upper surface of the main body  111  and the bottom surface of the edge ring FR through the gas supply line  72 . 
     Bias Power Source 
     Referring to  FIG. 7 , an example of a bias power source that applies a bias voltage to the edge ring FR in the plasma processing apparatus  1  will be described. 
     The bias power source  80  is connected to the edge ring FR. The bias power source  80  is configured to apply a DC voltage of, for example, 10 to 500 V to the edge ring FR. During the plasma processing, the bias power source  80  can  adjust a thickness of a plasma sheath above the edge ring FR by applying a predetermined voltage to the edge ring FR to correct distortion of the plasma sheath at an end portion of the substrate W. As a result, it is possible to improve the uniformity of an etching shape in the surface of the substrate W. Further, during the plasma processing, the bias power source  80  changes the bias voltage to be applied to the edge ring FR based on the thickness of the edge ring FP. detected in a transfer method to be described later. Accordingly, even when the thickness of the edge ring FR is changed due to the wear of the edge ring FR, the distortion of the plasma sheath at the end portion of the substrate W may be corrected. Therefore, it is possible to suppress the change of the etching shape in the surface of the substrate W due to the wear of the edge ring FR. As the bias power source  80 , in addition to the DC power source, a radio-frequency power source of 400 kHz to 100 MHz may be used. 
     Heating Mechanism 
     An example of a heating mechanism for heating the substrate W in the plasma processing apparatus  1  will be described with reference to  FIG. 8 . 
     The heating mechanism (heater)  90  is embedded in the main body  111 . The heating mechanism  90  includes a plurality of heaters  91   a  to  91   c,  power feed lines  92   a  to  92   c,  and an alternating-current (AC) power source  93 . For example, the heaters  91   a  to  91   c  are provided in a central region, an  intermediate region, and a peripheral region of the main body  111 , respectively, respective ends of the power feed lines  92   a  to  92   c  are connected to the heaters  91   a  to  91   c,  and the other ends of the power feed lines  92   a  to  92   c  are connected to the AC power source  93 . The AC power source  93  supplies a predetermined current to the heaters  91   a  to  91   c  through the power feed lines  92   a  to  92   c.  As a result, the temperature of the main body  111  can be raised for each region. 
     The above-described adsorption mechanism  60 , the heat transfer gas supply mechanism  70 , the bias supply (the application of the bias voltage to the edge ring FR by the bias power source  80 ), and the heating mechanism  90  may be combined appropriately. 
     Transfer Method 
     An example of a transfer method of one embodiment will be described with reference to  FIG. 9 . Hereinafter, in the plasma processing system PS 1  illustrated in  FIG. 1 , a case where the edge ring FR is installed in the stage in the process module PM 1  where the edge ring FR is not installed will be described by way of example. 
     In Step ST 101 , the controller CU selects an attachment target chamber of the edge ring FR. For example, the controller CU selects the process module PM 1  as the attachment target chamber of the edge ring FR. 
     In Step ST 102 , the controller CU selects the edge ring FR, and starts the transfer of the selected edge ring FR. In  one embodiment, first, the controller CU controls the transfer robot, (not illustrated) in the atmospheric transfer chamber LM to unload the edge ring FR accommodated in, for example, the container placed at the load port LP 3 . Subsequently, the controller CU controls the gate valve G 3  between the atmospheric transfer chamber LM and the load-lock chamber LL 1  to be opened. Subsequently, the controller CU controls the transfer robot to place the edge ring FR on the stage in the load-lock chamber LL 1 . Subsequently, the controller CU executes control of closing the gate valve G 3 , reducing the pressure in the load-lock chamber LL 1 , and switching the state of the load-lock chamber LL 1  to a vacuum state. Subsequently, the controller CU executes control of opening the gate valve G 2  between the load-lock chamber LL 1  and the vacuum transfer chamber TM. Subsequently, the controller CU executes control so that the fork FK of the transfer robot TR disposed in the vacuum transfer chamber TM receives the edge ring FR placed on the stage in the load-lock chamber LL 1 . 
     In Step ST 103 , the controller CU detects the position of the edge ring FR during the transfer. In one embodiment, the controller CU controls the transfer robot TR to move the fork FK holding the edge ring FR to a detection region of the position detection sensor S 12  provided in the vacuum transfer chamber TM. Subsequently, the position controller CT 12  detects the position of the edge ring FR by the position detection sensor S 12 . Further, the position controller CT 12   may store (save) the detected position of the edge ring FR. 
     In Step ST 104 , the controller CU determines whether or not there is misalignment of the edge ring FR based on the position of the edge ring FR detected in Step ST 103 . In one embodiment, the position controller CT 12  calculates a misalignment, amount of the edge ring FR from the reference position based on the position of the edge ring FR detected by the position detection sensor S 12  and a predetermined reference position, and transmits the calculated misalignment amount to the controller CU. The controller CU determines whether or not there is the misalignment of the edge ring FR based on the misalignment amount. When it is determined in Step ST 104  that the edge ring FR is misaligned, the controller CU advances the processing to Step ST 105 . When it is determined in Step ST 104  that the edge ring FR is not misaligned, the controller CU advances the processing to Step ST 107 . 
     In Step ST 105 , the controller CU determines whether the misalignment calculated in Step ST 104  is correctable or not. When it is determined in Step ST 105  that the misalignment is correctable, the controller CU advances the processing to Step ST 106 . Meanwhile, when it is determined in Step ST 105  that the misalignment is not correctable, the controller CU advances the processing to Step ST 110 . 
     In step S 106 , the controller CU corrects the misalignment amount of the edge ring FR or calculates a  correction value based on the misalignment amount calculated in Step ST 104 . 
     In Step ST 107 , the controller CU detects the thickness of the edge ring FR. In one embodiment, the controller CU controls the transfer robot IR to move the fork FK holding the edge ring FR to the detection region of the thickness detection sensor S 11  provided in the vacuum transfer chamber TM in consideration of the correction value. The detection region of the thickness detection sensor S 11  may be located at the same position as the detection region of the position detection sensor S 12 , or may be located at a different position. When the detection region of the thickness detection sensor S 11  is located at the same position as the detection region of the position detection sensor S 12 , the thickness of the edge ring FR can foe detected without moving the fork FK after the position of the edge ring FR is detected. 
     In Step ST 108 , the controller CU determines whether the thickness of the edge ring FR is within an allowable range or not. In one embodiment, the controller CU determines whether the thickness of the edge ring FR is within the allowable range or not, based on the thickness of the edge ring FR detected in Step ST 107 . When it is determined in Step ST 108  that the thickness of the edge ring FR is within the allowable range, the controller CU advances the processing to Step ST 109 . When it is determined in Step ST 108  that the thickness of the edge ring FR is outside the allowable range, the controller  CU advances the processing to Step ST 110 . 
     In Step ST 109 , the controller CU transfers the edge ring FR to the process module PM 1 . In one embodiment, first, the controller CU executes control of opening the gate valve G 1  between the vacuum transfer chamber TM and the process module PM 1 . Subsequently, the controller CU controls the transfer robot TR to place the edge ring FR on the stage of the process module PM 1  so as to correct the misalignment amount calculated by the position controller CT 12 . Thereafter, the controller CU ends the processing. 
     Further, when plasma processing is performed on the substrate W after the new edge ring FR is placed on the stage of the process module PM 1 , the controller CU may apply the plasma processing under conditions set based on the thickness of the edge ring FR calculated by the thickness controller CT 11 . This enables to improve the uniformity of the plasma processing. 
     The condition for the plasma processing may be, for example, a magnitude of the bias voltage that is supplied to the edge ring FR by the bias power source  80 . Further, the condition for the plasma processing may be, for example, a lifting amount of the edge ring FR by the raising/lowering pin  51 . Further, the condition for the plasma processing may be, for example, the supply pressure or the supply flow rate of the heat transfer gas supplied between the upper surface of the main body  111  and the bottom surface of the edge ring  FR by the heat transfer gas supply mechanism  70 . Further, the condition for the plasma processing may be, for example, a set temperature of the heater  91   c  that heats a peripheral region of the main body  111 . 
     In Step ST 110 , the controller CU issues an alarm and stops the transfer of the edge ring FR by the transfer robot TR. 
     In Step ST 111 , the controller CU transfers the edge ring FR to any of the load ports LP 1  to LP 3 . In one embodiment, first, the controller CU executes control of reducing the pressure in the load-lock chamber LL 2  to switch the state of the load-lock chamber LL 2  to a vacuum state. Subsequently, the controller CU executes control of opening the gate valve G 2  between the load-lock chamber LL 2  and the vacuum transfer chamber TM. Subsequently, the controller CU executes control so that the edge ring FR held by the fork FK of the transfer robot TR is placed on the stage in the load-lock chamber LL 2 . Subsequently, the controller CU executes control of closing the gate valve G 2  and switching the inside of the load-lock chamber LL 2  to the atmosphere. Subsequently, the controller CU executes control of opening the gate valve G 3  between the atmospheric transfer chamber LM and the load-lock chamber LL 2  to be opened. Subsequently, the controller CU executes control such that the transfer robot (not illustrated) in the atmospheric transfer chamber LM receives the edge ring FR placed on the stage in the load-lock chamber LL 2 ; for example,  the edge ring FR is accommodated in a container placed in the load port LP 3 . Further, the controller CU executes control of closing the gate valve G 3 . 
     In Step ST 112 , the controller CU shifts the state of the plasma processing system PS 1  to an operator-instruction waiting state. 
     In Step ST 113 , the controller CU determines whether “retry” or “not to retry” has been selected by the operator. When it is determined in Step ST 113  that the “retry” has been selected, the controller CU advances the processing to Step ST 114 . When it is determined in Step ST 113  that “not to retry” has been selected, the controller CU ends the processing. 
     In Step ST 114 , the controller CU determines whether or not there is another edge ring FR that can be used. When it is determined in Step ST 114  that there is another edge ring FR that can be used, the controller CU returns the processing to Step ST 102 . Meanwhile, when it is determined in Step ST 114  that there is no other edge ring FR that can be used, the controller CU ends the processing. 
     Another example of the transfer method of the embodiment will be described with reference to  FIG. 10 . Hereinafter, a case where the plasma processing system PS 1  illustrated in  FIG. 1  performs periodic inspection and replacement of the edge ring FR installed in the stage in the process module PM 1  will be described as an example. 
     In Step ST 201 , the controller CU selects an inspection  target chamber for the edge ring FR. For example, the controller CU selects the process module PM 1  as the inspection target chamber for the edge ring FR. 
     In Step ST 202 , the controller CU executes cleaning processing in the chamber selected in Step ST 201 . For example, the controller CU executes control so that the adsorption of the edge ring FR on the main body  111  is released by turning off the voltages applied from the DC power sources  61   a  and  61   b  of the adsorption mechanism  60  to the electrode plates  63   a  and  63   b . Subsequently, preferably, the controller CU executes control of cleaning processing in a state where the edge ring FR placed on the stage in the process module PM 1  is lifted by the raising/lowering pin  51  and separated from a stage placement surface. As a result, reaction products deposited on the rear surface of the edge ring FR through plasma processing can be removed. Alternatively, the controller CU may execute control of the cleaning processing without separating the edge ring FR from the stage placement surface. The cleaning processing refers to processing of removing deposits in the process module PM 1  generated by the plasma processing by plasma or the like of a processing gas to stabilize the inside of the process module PM 1  in a clean state. Application of the cleaning processing can suppress deposits in the process module PM 1  from being stirred up when the edge ring FR is unloaded from the inside of the process module PM 1 . As the processing gas, for example, an oxygen (O 2 )  gas, a fluorocarbon (CF)-based gas, a nitrogen (N 2 ) gas, an argon (Ar) gas, a He gas, or a mixed gas of two or more of these can be used. Further, when the cleaning processing of the process module PM 1  is performed, in order to protect the electrostatic chuck of the stage, the cleaning processing may be performed in a state where the substrate W such as a dummy wafer is placed on the upper surface of the electrostatic chuck, depending on the processing conditions. When there is no deposit in the process module PM 1  or when there is no influence on the transfer of the edge ring, the cleaning processing may be omitted. That is, Step ST 202  may be omitted. 
     In Step ST 203 , the controller CU executes control so that the edge ring FR is taken out from the inside of the process module PM 1 . In one embodiment, first, the controller CU executes control of opening the gate valve G 1  between the vacuum transfer chamber TM and the process module PM 1 . Subsequently, the controller CU executes control so that the fork FK of the transfer robot TR disposed in the vacuum transfer chamber TM receives the edge ring FR placed on the stage in the process module PM 1 . More specifically, first, the edge ring FR is lifted at the distal end of the raising/lowering pin  51  by raising the raising/lowering pin  51  by the actuator  52 . Subsequently, the fork FK enters below the edge ring FR in the process module PM 1 . Subsequently, the raising/lowering pin  51  is lowered to place the edge ring FR on the fork FK. Subsequently, the controller CU executes  control of transferring the edge ring FR to the vacuum transfer chamber TM and closing the gate valve G 1 . 
     Steps ST 204  to ST 215  may be the same as steps ST 103  to ST 114  described above. Further, Step ST 216  may be the same as Step ST 102  described above. 
     According to the first embodiment described above, the thickness detection sensor S 11  for detecting the thickness of the edge ring FR is provided in the vacuum transfer chamber TM outside the process modules PM 1  to PM 4  of the plasma processing system PS 1 . Accordingly, it is possible to detect the amount of consumption of the edge ring FR in an environment where the edge ring FR is not exposed to plasma. As a result, the thickness of the edge ring FR can be detected with high accuracy. 
     In contrast, in a case where the thickness detection sensors are provided in the process modules PM 1  to PM 4 , for example, a view port through which light is transmitted is provided in the top plate or the sidewall of the process module PM 1 , and the edge ring FR is exposed to light through the view port so as to detect the thickness of the edge ring FR. In this case, since the view port can be etched by plasma, the view port becomes a new consumable member. Then, maintenance for periodically replacing the view port newly occurs; thus, productivity decreases, and the cost increases. Further, when a surface of the view port is consumed or an etching product adheres to the surface of the view port, the  signal-to-noise ratio of the detection value is reduced, which deteriorates the detection accuracy. 
     Further, according to the first embodiment, the thickness of the edge ring FR is detected before the edge ring FR is placed on the stage of the process module PM 1 . When the detected thickness of the edge ring FR is within the allowable range, the edge ring FR is placed on the stage of the process module PM 1 . Meanwhile, when the detected thickness of the edge ring FR is outside the allowable range, the edge ring FR is retrieved and replaced. As a result, it is possible to prevent an error in attaching of the edge ring FR. 
     Second Embodiment 
     An example of a plasma processing system of a second embodiment will be described with reference to  FIG. 11 . A plasma processing system PS 2  of the second embodiment is different from the plasma processing system PS 1  of the first embodiment in that a thickness detection sensor S 11  and a position detection sensor S 12  are provided in the vicinity of a gate valve G 1 . Other aspects may be the same as those of the plasma processing system PS 1  of the first embodiment. 
     The thickness detection sensor S 11  is provided in the vicinity of the gate valve G 1  between the vacuum transfer chamber TM and each of the process modules PM 1  to PM 4 . The thickness detection sensor S 11  detects the thickness of the edge ring FR in a transfer path through which the fork FK of the transfer robot TR transfers the edge ring FR between the  vacuum transfer chamber TM and each of the process modules PM 1  to PM 4 . 
     The position detection sensor S 12  is provided in the vicinity of the gate valve G 1  between the vacuum transfer chamber TM and each of the process modules PM 1  to PM 4 . The position detection sensor S 12  detects the position of the edge ring FR in a transfer path through which the fork FK of the transfer robot TR transfers the edge ring FR between the vacuum transfer chamber TM and each of the process modules PM 1  to PM 4 . 
     According to the second embodiment, the thickness detection sensor S 11  for detecting the thickness of the edge ring FR is provided in the vacuum transfer chamber TM outside the process modules PM 1  to PM 4  of the plasma processing system PS 2 . Accordingly, it is possible to detect the amount of consumption of the edge ring FR in an environment where the edge ring FR is not exposed to plasma. As a result, the thickness of the edge ring FR can be detected with high accuracy. 
     Further, according to the second embodiment, the thickness of the edge ring FR is detected before the edge ring FR is placed on the stage of the process module PM 1 . When the detected thickness of the edge ring FR is within the allowable range, the edge ring FR is placed on the stage of the process module PM 1 . Meanwhile, when the detected thickness of the edge ring FR is outside the allowable range, the edge ring FR is  retrieved and replaced. As a result, it is possible to prevent an error in attaching of the edge ring FR. 
     Further, according to the second embodiment, the thickness detection sensor  311  and the position detection sensor S 12  are provided in the vicinity of the gate valve G 1  between the vacuum transfer chamber TM and each of the process modules PM 1  to PM 4 . Therefore, the transfer robot TR can calculate the thickness and misalignment of the edge ring FR while transferring the edge ring FP from the vacuum transfer chamber TM to the process modules PM 1  to PM 4 . Therefore, throughput of the edge ring transfer is improved compared with the plasma processing system PS 1 . 
     Third Embodiment 
     An example of a plasma processing system of a third embodiment will be described with reference to  FIG. 12 . A plasma processing system PS 3  of the third embodiment is different from the plasma processing system PS 2  of the second embodiment in that a function of a thickness detection sensor S 11  is integrated with a position detection sensor S 12 . Other aspects may be the same as those of the plasma processing system PS 2  of the second embodiment. 
     The plasma processing system PS 3  includes a position detection sensor S 12  and a combined detection sensor S 13  provided in the vicinity of a gate valve G 1  between a vacuum transfer chamber TM and each of process modules PM 1  to PM 4 . 
     The combined detection sensor S 13  has a function of  detecting a position of an edge ring FR and a function of detecting a thickness of an edge ring FR. 
     According to the third embodiment, the thickness detection sensor S 11  for detecting the thickness of the edge ring FR is provided in the vacuum transfer chamber TM outside the process modules PM 1  to PM 4  of the plasma processing system PS 3 . Accordingly, it is possible to detect the amount of consumption of the edge ring FP in an environment where the edge ring FR is not exposed to plasma. As a result, the thickness of the edge ring FR can be detected with high accuracy. 
     Further, according to the third embodiment, the thickness of the edge ring FR is detected before the edge ring FR is placed on the stage of the process module PM 1 . When the detected thickness of the edge ring FR is within the allowable range, the edge ring FR is placed on the stage of the process module PM 1 . Meanwhile, when the detected thickness of the edge ring FR is outside the allowable range, the edge ring FR is retrieved and replaced. As a result, it is possible to prevent an error in attaching of the edge ring FR. 
     Further, according to the third embodiment, the position detection sensor S 12  and the combined detection sensor S 13  are provided in the vicinity of the gate valve G 1  between the vacuum transfer chamber TM and each of the process modules PM 1  to PM 4 . Therefore, the transfer robot TR can calculate the thickness and misalignment of the edge ring FR while  transferring the edge ring FR from the vacuum transfer chamber TM to the process modules PM 1  to PM 4 . Therefore, throughput of the edge ring transfer is improved compared with the plasma processing system PS 1 . 
     Further, according to the third embodiment, the function of the thickness detection sensor S 11  is integrated with the position detection sensor S 12 . As a result, the number of sensors can be reduced. 
     Fourth Embodiment 
     An example of a plasma processing system of a fourth embodiment will be described with reference to  FIG. 13 . A plasma processing system PS 4  of the fourth embodiment is different from the plasma processing system PS 1  of the first embodiment in that a buffer BF for storing an edge ring FR is provided in an atmospheric transfer chamber LM. 
     The buffer BF is provided in the atmospheric transfer chamber LM. The buffer BF accommodates a plurality of edge rings FR in multiple stages thereinside. The buffer BF is located at a position accessible by a transfer robot (not illustrated) in the atmospheric transfer chamber LM. The transfer robot transfers an edge ring FR between the buffer BF and each of load-lock chambers LL 1  and LL 2 . 
     In this way, the other components may be identical to the plasma processing systems PS 1  to PS 3 , except that the edge ring FR is accommodated in the buffer BF. 
     According to the fourth embodiment, the thickness  detection sensor S 1   1  for detecting the thickness of the edge ring FR is provided in the vacuum transfer chamber TM outside the process modules PM 1  to PM 4  of the plasma processing system PS 4 . Accordingly, it is possible to detect the amount of consumption of the edge ring FR in an environment where the edge ring FR is not exposed to plasma. As a result, the thickness of the edge ring FR can be detected with high accuracy. 
     Further, according to the fourth embodiment, the thickness of the edge ring FR is detected before the edge ring FR is placed on the stage of the process module PM 1 . When the detected thickness of the edge ring FR is within the allowable range, the edge ring FR is placed on the stage of the process module PM 1 . Meanwhile, when the detected thickness of the edge ring FR is outside the allowable range, the edge ring FR is retrieved and replaced. As a result, it is possible to prevent an error in attaching of the edge ring FR. 
     Fifth Embodiment 
     An example of a plasma processing system of a fifth embodiment will be described with reference to  FIG. 14 . A plasma processing system PS 5  of the fifth exemplary embodiment is different from the plasma processing system PS 1  of the first exemplary embodiment in that a storage chamber SC for storing an edge ring FR is connected to a vacuum transfer chamber TM. 
     The storage chamber SC is connected to the vacuum  transfer chamber TM through a gate valve G 4 . The storage chamber SC accommodates a plurality of edge rings FR in multiple stages thereinside. The storage chamber SC is located at a position accessible by the transfer robot TR. The transfer robot TR transfers the edge ring FR between the storage chamber SC and process modules PM 1 , PM 2 , and PM 4 . 
     In this way, the other components of the plasma processing systems PS 1  to PS 3  may be used, except that the edge ring FR is accommodated in the storage chamber SC. 
     According to the fifth embodiment, the thickness detection sensor S 11  for detecting the thickness of the edge ring FR is provided in the vacuum transfer chamber TM outside the process modules PM 1 , PM 2 , and PM 4  of the plasma processing system PS 5 . Accordingly, it is possible to detect the amount of consumption of the edge ring FR in an environment where the edge ring FR is not exposed to plasma. As a result, the thickness of the edge ring FR can be detected with high accuracy. 
     Further, according to the fifth embodiment, the thickness of the edge ring FR is detected before the edge ring FR is placed on the stage of the process module PM 1 . When the detected thickness of the edge ring FR is within the allowable range, the edge ring FR is placed on the stage of the process module PM 1 . Meanwhile, when the detected thickness of the edge ring FR is outside the allowable range, the edge ring FR is retrieved and replaced. As a result, it is possible to prevent  an error in attaching of the edge ring FR. 
     It shall be understood that the embodiments disclosed herein are illustrative and are not restrictive in all aspects. The embodiments described above may be omitted, replaced, or modified in various forms without departing from the scope and spirit of the appended claims. 
     In the embodiments described above, the case of detecting the thickness of the edge ring FR has been described. However, the present disclosure is not limited thereto. For example, the present disclosure may be similarly applied to a case where, instead of the edge ring FR, the thickness of another consumable member (for example, a cover ring, a top plate of an upper electrode, or the like) attached in the process module PM is detected. 
     In the embodiments described above, the thickness detection sensor S 11  that detects the thickness of the consumable member is disposed outside the chamber in the plasma processing systems PS 1  to PS 5 . However, the present disclosure is not limited thereto. For example, instead of the thickness detection sensor S 11 , a state detection sensor that detects the state of the consumable member, such as the surface state of the consumable member, may be disposed. 
     Further, when the state of the consumable member is detected by the state detection sensor, detecting the state of the consumable member in an area (straight line or surface) instead of a spot (one point) enables to detect a shape  (inclination, irregularity, distortion, deflection, warp, or the like) of the consumable member. As an example, the state of the edge ring FR at a plurality of points (or lines) can be detected by rotating the edge ring FR. Further, by using a sensor such as a line sensor, the state of the edge ring FR at a plurality of points (or lines) can be detected. Further, these materials may be combined. As a result, it is possible to detect shapes such as inclination, irregularities, distortion, deflection, and warpage over the entire periphery of the edge ring FR.