Patent Publication Number: US-2022236202-A1

Title: Holder temperature detection method, holder monitoring method and substrate processing apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Japanese Patent Application No. 2021-008971 filed on Jan. 22, 2021, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a holder temperature detection method, a holder monitoring method, and a substrate processing apparatus. 
     BACKGROUND 
     A substrate processing apparatus having a rotatable holder for holding a substrate is known. Japanese Laid-open Patent Publication No. 2018-178163 discloses a movable body structure which includes a processing container configured to enable processing in a vacuum environment, a fixed part disposed in the processing container, a movable part provided to be movable with respect to the fixed part, a transmission and reception module provided in the fixed part and having an airtight seal structure, and a sensor module provided in the movable part and having an airtight seal structure, wherein the transmission and reception module and the sensor module transmit or receive a signal in a non-contact manner. 
     SUMMARY 
     However, in the substrate processing apparatus, it is required to detect a temperature of a rotatable holder. 
     For the above problem, in one aspect, one object of the present disclosure is to provide a holder temperature detection method for detecting a temperature of a rotatable holder, a holder monitoring method, and a substrate processing apparatus. 
     As one example of the present disclosure, a holder temperature detection method which measures a temperature of a rotatable holder that holds a substrate is provided. The method comprises: a step of irradiating a fluorescent body thermally mounted on the holder with a light pulse having a first wavelength; a step of detecting fluorescence having a second wavelength emitted from the fluorescent body due to the light pulse; and a step of estimating the temperature of the holder based on the detected fluorescence. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a longitudinal cross-sectional view illustrating an example of a substrate processing apparatus according to an embodiment. 
         FIG. 2  is a longitudinal cross-sectional view illustrating the example of the substrate processing apparatus according to the present embodiment. 
         FIG. 3  is an example of a flowchart describing a holder monitoring method. 
         FIG. 4  is an example of a graph illustrating a change in temperature when a thermal conductivity between a holder and a substrate is a reference value. 
         FIG. 5  is an example of a graph illustrating the change in temperature when the thermal conductivity between the holder and the substrate is 50% of a reference value. 
         FIG. 6  is an example of a graph illustrating a change in temperature of the substrate. 
         FIG. 7  is an example of a graph illustrating an estimated time required to cool the substrate. 
         FIG. 8  is an example of a graph illustrating an increase in an integral value. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an embodiment for implementing the present disclosure will be described with reference to the accompanying drawings. In the specification and drawings, substantially the same constituents are designated by the same reference numerals to omit duplicate explanations. 
     &lt;Substrate Processing Apparatus&gt; 
     A substrate processing apparatus  100  according to the present embodiment will be described with reference to  FIGS. 1 and 2 .  FIGS. 1 and 2  are longitudinal cross-sectional views illustrating an example of the substrate processing apparatus  100  according to the present embodiment. Further,  FIG. 1  illustrates a state in which a contact plate  37  of a refrigerating device  30  is separated from a holder  21 .  FIG. 2  illustrates a state in which the contact plate  37  of the refrigerating device  30  is in contact with the holder  21 . 
     The substrate processing apparatus  100  illustrated in  FIG. 1  is, for example, a physical vaper deposition (PVD) apparatus that forms a film on a substrate W such as a semiconductor wafer to be processed inside a processing container  10  in which an ultra-high vacuum and extremely low temperature atmosphere is formed and the substrate is processed with a processing gas. Here, the ultra-high vacuum means a pressure atmosphere of, for example, 10 −5  Pa or less, and the extremely low temperature means a temperature atmosphere of −30° C. or lower, for example, about −200° C. 
     The substrate processing apparatus  100  includes the processing container  10 , the holder  21  that holds the substrate W inside the processing container  10 , the refrigerating device  30 , a rotary support  40  that rotatably supports the holder  21 , a first elevating device  50  that moves the holder  21  up and down, and a second elevating device  60  that moves the refrigerating device  30  up and down. The substrate processing apparatus  100  illustrated in  FIGS. 1 and 2  has been described as including two elevating devices which are the first elevating device  50  that moves the holder  21  up and down and the second elevating device  60  that moves the refrigerating device  30  up and down, but may have a structure in which the holder  21  and the refrigerating device  30  are moved up and down by a common elevating device. 
     In the inside of the processing container  10 , the holder  21  is disposed at the lower side. Further, above the holder  21 , a plurality of target holders  12  are fixed in a state in which the plurality of target holders  12  have a predetermined inclination angle θ with respect to a horizontal plane. A target T is mounted on a lower surface of each of the target holders  12 . In  FIGS. 1 and 2 , the number of target holders  12  may be one or three or more. Further, a material of the target may differ or be the same for each of the target holders  12 . 
     The processing container  10  is configured so that the inside thereof is depressurized to an ultra-high vacuum by operating an exhaust device (not illustrated) such as a vacuum pump. Further, a processing gas (for example, a rare gas such as argon (Ar), krypton (Kr), neon (Ne), or a nitrogen (N 2 ) gas) required for sputter film formation is supplied to the processing container  10  via a gas supply pipe (none of which is illustrated) that communicates with a processing gas supply device. 
     An alternating current (AC) voltage or a direct current (DC) voltage is applied from a plasma generation power supply (not illustrated) to the target holder  12 . When an AC voltage is applied from the plasma generation power supply to the target holder  12  and the target T, plasma is generated inside the processing container  10 , the rare gas or the like inside the processing container  10  is ionized, and the target T is sputtered by the ionized rare gas element or the like. Atoms or molecules of the sputtered target T are deposited on a surface of the substrate W that is held in the holder  21  to face the target T. 
     Due to the target T being inclined with respect to the substrate W, an incident angle at which sputtered particles sputtered from the target T are incident on the substrate W can be adjusted, and in-plane uniformity of a film thickness of a film formed on the substrate W can be enhanced. Further, in the inside of the processing container  10 , even when each of the target holders  12  is installed at the same inclination angle θ, the incident angle of the sputtered particles on the substrate W can be changed by moving the holder  21  up and down to change a distance between the target T and the substrate W. Therefore, for each of the applied targets T, the holder  21  is controlled to move up and down and to have a suitable distance with respect to each of the targets T. 
     The holder  21  is made of a material (for example, Cu) having a high thermal conductivity and is formed to have a disk shape. 
     An electrostatic chuck (ESC) plate  22  is provided on the side of an upper surface of the holder  21 . The ESC plate  22  has a chuck electrode embedded in a dielectric. The chuck electrode is configured to have a predetermined potential via wiring. With such a configuration, the substrate W can be adsorbed by an ESC, and the substrate W can be fixed to the upper surface of the electrostatic chuck plate  22 . 
     A cylindrical stand  23  is provided on the side of a lower surface of the holder  21 . The cylindrical stand  23  is made of a material (for example, austenitic stainless steel, ferritic stainless steel, or the like) having a low thermal conductivity and is formed to have a cylindrical shape. The cylindrical stand  23  supports the holder  21 . Further, the cylindrical stand  23  partitions a space  15   a  inside the cylindrical stand  23  and a space  15   b  outside the cylindrical stand  23 . Further, the holder  21 , the ESC plate  22 , and the cylindrical stand  23  constitute a rotating body  20  that rotates on a rotating axis CL. The cylindrical stand  23  may have a space that is a lightening hole formed in a cylindrical shape. Thus, it is possible to further reduce the thermal conductivity of the cylindrical stand  23 . 
     The refrigerating device  30  includes a cold head  31 , a cold link  32 , and a heat transfer plate assembly  33 . 
     The cold head  31  is supported by a support member  38 . Further, the cold head  31  is cooled by a refrigerator (not illustrated). From the viewpoint of cooling capacity, the refrigerator preferably uses a Gifford-McMahon (GM) cycle. 
     The cold link  32  is formed to extend from the cold head  31  toward the holder  21 . The cold link  32  is made of a material (for example, Cu) having a high thermal conductivity and thermally connects the cold head  31  to the heat transfer plate assembly  33 . 
     The heat transfer plate assembly  33  has a plate  34 , concentric bellows  35   a  and  35   b , a plate  36 , and a contact plate  37 . The plate  34  is thermally connected to the cold link  32 . The concentric bellows  35   a  and  35   b  thermally connect the plate  34  to the plate  36 . The thermally connected contact plate  37  is provided on an upper surface of the plate  36 . 
     With such a configuration, the cold head  31  cools the contact plate  37  of the heat transfer plate assembly  33  to an extremely low temperature via the cold link  32  and the heat transfer plate assembly  33 . Further, the contact plate  37  can be brought into contact with a bottom surface of the holder  21  by moving the support member  38  up or moving the holder  21  down. Further, the holder  21  and the contact plate  37  can be separated from each other by moving the support member  38  down or moving the holder  21  up. 
     The rotary support  40  includes an inner ring member  41 , a bearing  42 , a bearing  43 , and an outer ring member  44 . The bearing  42  is disposed between the inner ring member  41  and the cylindrical stand  23 . Further, the bearing  43  is disposed between the outer ring member  44  and the cylindrical stand  23 . With such a configuration, the cylindrical stand  23  is supported rotatably. 
     Further, the bellows  45   a  is provided between the inner ring member  41  and the support member  38 . The bellows  45   b  is provided between the outer ring member  44  and a bottom surface  11 . The bearings  42  and  43  rotatably support the cylindrical stand  23  and seal the cylindrical stand  23  with a magnetic fluid. Thus, the space  15   a  in which the refrigerating device  30  is disposed is made airtight by the bearing  42  and the bellows  45   a . Further, the space  15   b  is made airtight by the bearing  43  and the bellows  45   b.    
     Further, the substrate processing apparatus  100  includes a rotary motor (not illustrated) that rotates the cylindrical stand  23 . Thus, the rotary motor can rotate the cylindrical stand  23  to rotate the holder  21 . 
     The first elevating device  50  moves the holder  21  up and down by moving the cylindrical stand  23 , the inner ring member  41 , and the outer ring member  44  up and down. 
     The second elevating device  60  moves the contact plate  37  up and down by moving the support member  38  up and down. 
     The vacuum pump  70  exhausts internal air of the space  15   a  through an opening (not illustrated) provided in the support member  38 . 
     Further, the substrate processing apparatus  100  includes a temperature detection part that detects the temperature of the rotating holder  21 . The temperature detection part includes fluorescent bodies  80   a  and  80   b , a detection part (one end of an optical waveguide)  81 , an optical fiber (an optical waveguide)  82 , and a processing unit  83 . 
     The fluorescent bodies  80   a  and  80   b  are provided on the surface of the holder  21 . For example, the fluorescent bodies  80   a  and  80   b  are disposed on the side of the bottom surface in the vicinity of an end portion of the rotating holder  21  to be thermally connected thereto. Like the fluorescent body  80   a , the fluorescent bodies  80   a  may be disposed on the back surface of the holder  21 . Further, like the fluorescent body  80   b , a recessed portion may be formed in the back surface of the holder  21 , and the fluorescent bodies  80   b  may be disposed inside the recessed portion. Further, the fluorescent bodies  80   a  and  80   b  may be formed on metal pellets having a high thermal conductivity such as Cu and Al, and the metal pellets having the fluorescent bodies may be mounted on the holder  21 . Further, a plurality of fluorescent bodies  80   a  and  80   b  may be disposed in a circumferential direction of the holder  21 . 
     The fluorescent bodies  80   a  and  80   b  are excited when irradiated with light of a first wavelength, emit light (fluorescence) having a second wavelength different from the first wavelength and transition to the ground state. As the fluorescent bodies  80   a  and  80   b , for example, YAG or the like can be used. 
     The processing unit  83  includes a light source (not illustrated) that is provided outside the processing container  10  to irradiate pulsed light of the first wavelength, and a detector (not illustrated) that detects light of the second wavelength. One end of the optical fiber (optical waveguide)  82  is connected to the detection part  81  in the processing container  10 , and the other end is connected to the processing unit  83  (a light source, a detector) via a fitting  82   a  passing through the bottom surface  11  of the processing container  10 . With such a configuration, the light source of the processing unit  83  irradiates light  86   a  from the detection part  81  via the optical fiber  82 . Further, the light  86   b  incident on the detection part  81  is guided to the detector of the processing unit  83  via the optical fiber  82 . 
     Further, the temperature detection part includes a position adjusting part that adjusts the position of the detection part  81 . In the example illustrated in  FIGS. 1 and 2 , the position adjusting part includes a support member  84  and a contact member  85 . The support member  84  stands from the outer ring member  44  and supports the detection part  81  to be movable in a vertical direction. Specifically, the detection part  81  is inserted into a hole  84   a  provided in the support member  84 , and the detection part  81  is supported to be movable in the vertical direction. The contact member  85  stands from the bottom surface  11  of the processing container  10 . Thus, in a state illustrated in  FIG. 1 , an enlarged diameter portion of the detection part  81  is engaged with an edge of the hole  84   a , and thus a distance  87  from the fluorescent body  80   a  to the detection part  81  is maintained. On the other hand, in a state illustrated in  FIG. 2 , a bottom portion of the detection part  81  is engaged with the contact member  85 , thus the detection part  81  is pushed up from the hole  84   a , and the distance  87  from the fluorescent body  80   b  to the detection part  81  is maintained. In this way, the position adjusting part can constantly maintain the distance  87  from the fluorescent bodies  80   a  and  80   b  to the detection part  81  by adjusting a position of the detection part  81 . The distance  87  is preferably 1 mm or more and 50 mm or less, and more preferably 5 mm or more and 20 mm or less. 
     Further, the substrate processing apparatus  100  includes a controller  90  that controls the entire substrate processing apparatus  100 . A temperature of the holder  21  detected by the temperature detection part (the processing unit  83 ) is input to the controller  90 . Further, the controller  90  controls a rotary motor (not illustrated) that rotates the cylindrical stand  23 , the first elevating device  50 , the second elevating device  60 , and the like. 
     &lt;Holder Temperature Detection Method&gt; 
     First, the temperature detection of the holder  21  when the holder  21  is rotating will be described with reference to  FIG. 1 . In a deposition process in which sputtered particles are deposited on the substrate W, as illustrated in  FIG. 1 , the holder  21  is separated from the contact plate  37 , and the holder  21  rotates. As the holder  21  rotates, the fluorescent body  80   a  also rotates. 
     At the timing when the rotating holder  21  reaches a predetermined angle and the fluorescent body  80   a  and the detection part  81  are aligned (in other words, the timing when the fluorescent body  80   a  reaches a radiation direction and a detection direction of the detection part  81 ), the processing unit  83  irradiates the fluorescent body  80   a  with the pulsed light having the first wavelength. Then, the processing unit  83  detects the fluorescence having the second wavelength from the fluorescent body  80   a . Then, the processing unit  83  estimates the temperature of the holder  21  based on the detected fluorescence. 
     Here, the fluorescent body  80   a  to which the pulsed light of the first wavelength is irradiated emits the fluorescence having the second wavelength while attenuating the intensity thereof. The intensity attenuation of the fluorescence emitted by the fluorescent body  80   a  depends on the temperature of the fluorescent body  80   a  (in other words, the temperature of the holder  21 ). The processing unit  83  calculates an attenuation time constant based on the intensity attenuation of the detected fluorescence. Further, the processing unit  83  stores, in advance, a table in which the attenuation time constant and the temperature of the holder  21  are associated with each other. The processing unit  83  estimates (detects) the temperature of the holder  21  based on the table and the calculated attenuation time constant. 
     As the fluorescent body  80   a , it is preferable to use a material in which the intensity of the fluorescence is attenuated in a short time (for example, 1 to 10 ms) at an extremely low temperature. As a result, a detection time can be shortened. Further, it is possible to suppress a change in a length of an optical path from the fluorescent body  80   a  to the detection part  81  due to movement of the fluorescent body  80   a  (rotation of the holder  21 ). The intensity of the detected fluorescence may be corrected based on a relationship between the position and the angle of the fluorescent body  80   a  and the detection part  81 . 
     Further, the temperature of the holder  21  can be periodically detected according to a rotation speed of the holder  21  and the number of the fluorescent bodies  80   a  by providing a plurality of fluorescent bodies  80   a  in the circumferential direction. 
     Further, a plurality of detection parts  81  may be provided in an arc shape centered on the rotation axis CL. Thus, even in a configuration in which the rotation speed of the holder  21  is high or a configuration in which a fluorescent body  80   a  having a long attenuation time of the intensity of the fluorescence is used, the temperature of the holder  21  can be suitably detected. 
     Further, the example in which the processing unit  83  estimates the temperature based on the temperature dependence of the fluorescence intensity attenuation has been described, but the present disclosure is not limited thereto. The temperature of the holder  21  may be estimated based on temperature dependence of other optical characteristics of the fluorescence (for example, a band edge of Si and the like). 
     Next, the temperature detection of the holder  21  at the time of cooling the holder  21  will be described with reference to  FIG. 2 . In a cooling process, the holder  21  descends by a distance L 1  so that a rotation angle of the holder  21  is an angle at which the fluorescent body  80   b  and the detection part  81  are aligned with each other. Thus, as illustrated in  FIG. 2 , the holder  21  comes into contact with the contact plate  37  and is cooled. 
     The processing unit  83  irradiates the fluorescent body  80   b  with the pulsed light having the first wavelength. Then, the processing unit  83  detects the fluorescence having the second wavelength from the fluorescent body  80   b . Then, the processing unit  83  estimates the temperature of the holder  21  based on the detected fluorescence. 
     Here, the fluorescent body  80   b  is disposed in the recessed portion of the holder  21 . As a result, the temperature of the holder  21  can be measured at a position closer to the substrate W. Therefore, when the temperature of the substrate W is estimated based on the detected temperature of the holder  21 , the estimation accuracy can be enhanced. 
     Further, the distance  87  from the fluorescent body  80   b  illustrated in  FIG. 2  to the detection part  81  is maintained at the distance  87  from the fluorescent body  80   a  illustrated in  FIG. 1  to the detection part  81  by the position adjusting part (the support member  84  and the contact member  85 ). Thus, an effect of the intensity attenuation according to the length of the optical path from the fluorescent bodies  80   a  and  80   b  to the detection part  81  can be made uniform. Therefore, even in the state of  FIG. 2 , the temperature of the holder  21  can be detected in the same manner as in the state of  FIG. 1 . 
     As described above, according to the substrate processing apparatus  100  of the present embodiment, the temperature of the holder  21  can be detected using the temperature detection part (the fluorescent bodies  80   a  and  80   b , the detection part  81 , the optical fiber  82 , and the processing unit  83 ). 
     Incidentally, as a method of measuring a temperature of a rotating body, a configuration in which an element for measuring the temperature is provided in the rotating body, and the temperature is measured from the outside through a conductive ring and a slip ring having a sliding contact point is known. However, in the substrate processing apparatus  100  according to the present embodiment, it is difficult to apply the slip ring because a diameter of the rotating body  20  is large. Further, since the holder  21  is cooled to an extremely low temperature, it is difficult to measure the temperature of the holder  21  using a pyrometer. 
     On the other hand, the temperature detection part of the present embodiment can detect the temperature of the holder  21  by maintaining the fluorescent bodies  80   a  and  80   b  provided on the rotating holder  21  and the detection part  81  in a non-contact manner. Further, the temperature detection part of the present embodiment can detect the temperature of the holder  21  which is cooled to an extremely low temperature. 
     &lt;Holder Monitoring&gt; 
     Next, monitoring of the holder  21  will be described with reference to  FIG. 3 .  FIG. 3  is an example of a flowchart illustrating a method of monitoring the holder  21 . Here, a case in which the controller  90  monitors a heat transfer state between the holder  21  and the substrate W and performs a film forming process will be described as an example. 
     In Step S 101 , the holder  21  is rotated to a rotation angle of φ 0 . Here, the substrate processing apparatus  100  has an encoder (not illustrated) that detects the rotation angle of the holder  21 . A detection angle obtained by the encoder is input to the controller  90 . The controller  90  controls a rotary motor (not illustrated) to rotate the holder  21  to the rotation angle of φ 0 . The rotation angle of φ 0  is the rotation angle of the holder  21  at which the fluorescent body  80   b  is aligned with the detection part  81 . 
     In Step S 102 , the contact plate  37  is brought into contact with the holder  21 . Here, the controller  90  controls the first elevating device  50  to move the holder  21  down. As a result, the state of the substrate processing apparatus  100  becomes the state illustrated in  FIG. 2 . 
     In Step S 103 , the temperature of the holder  21  is lowered to a predetermined temperature T 0  by cooling. The cooling of the holder  21  is started by thermally connecting the cold head  31  and the holder  21  to each other via the cold link  32  and the heat transfer plate assembly  33 . Here, the processing unit  83  irradiates the fluorescent body  80   b  with pulsed light and measures (estimates) the temperature of the holder  21  based on the detected fluorescence of the fluorescent body  80   b . When the temperature of the holder  21  becomes lower than or equal to the predetermined temperature T 0 , the process of the controller  90  proceeds to Step S 104 . 
     In Step S 104 , the substrate W is placed, and a heat transfer gas is supplied. A high-temperature substrate W is placed on a mounting surface of the holder  21  by a transport device (not illustrated). The controller  90  controls a power supply (not illustrated) that applies electric power to the electrode of the ESC plate  22  to cause the ESC plate  22  to adsorb/attract the substrate W. Further, the controller  90  controls a heat transfer gas supply (not illustrated) to supply the heat transfer gas (for example, He gas) between a back surface of the substrate W and an upper surface of the ESC plate  22 . The upper surface of the ESC plate  22  has a concave portion and a convex portion that comes in contact with a bottom surface of the concave portion, and the upper surface of the convex portion is in contact with the back surface of the substrate W. The heat transfer gas is supplied to a space formed by the back surface of the substrate W and the concave portion. 
     In Step S 105 , an integral value E of the temperature change of the holder  21  from the placement of the substrate W to a predetermined time is calculated. Here, the processing unit  83  irradiates the fluorescent body  80   b  with pulsed light and detects the temperature of the holder  21  based on the detected fluorescence of the fluorescent body  80   b . Further, the processing unit  83  acquires a time change T (t) of the temperature of the holder  21  by repeating the temperature measurement in a predetermined cycle. The controller  90  calculates the integral value E (=(T(t)−T0)Δt) based on the time change T(t) of the temperature of the holder  21 , the initial temperature T 0 , and a duration Δt. The integral value E is a value that depends on a heat transfer state between the holder  21  and the substrate W. When the heat transfer state between the holder  21  and the substrate W is degraded, the integral value E becomes smaller. 
     In Step S 106 , the controller  90  determines whether or not the integral value E is greater than or equal to a threshold value E 0 . When the integral value E is greater than or equal to the threshold value E 0  (S 106 : Yes), the process of the controller  90  proceeds to Step S 107 . When the integral value E is not greater than or equal to the threshold value E 0  (S 106 : No), the process of the controller  90  proceeds to Step S 111 . 
     In Step S 107 , the controller  90  performs the film forming process. The controller  90  controls the first elevating device  50  to move the holder  21  up. Then, the controller  90  controls the rotary motor (not illustrated) to rotate the holder  21 . As a result, the state of the substrate processing apparatus  100  becomes the state illustrated in  FIG. 1 . Then, the sputtered particles are emitted from the target T to form a film on the substrate W. The processing unit  83  irradiates the pulsed light at the timing when the fluorescent body  80   a  rotating together with the holder  21  is disposed on the detection part  81 , and measures (estimates) the temperature of the holder  21  based on the detected fluorescence of the fluorescent body  80   a.    
     In Step S 108 , the holder  21  is rotated to the rotation angle of φ 0 . Here, the substrate processing apparatus  100  has an encoder (not illustrated) that detects the rotation angle of the holder  21 . The detection angle of the encoder is input to the controller  90 . The controller  90  controls the rotary motor (not illustrated) to rotate the holder  21  to the rotation angle of φ 0 . The rotation angle of φ 0  is the rotation angle of the holder  21  at which the fluorescent body  80   b  is aligned with the detection part  81 . 
     In Step S 109 , the contact plate  37  is brought into contact with the holder  21 . Here, the controller  90  controls the first elevating device  50  to move the holder  21  down. As a result, the state of the substrate processing apparatus  100  becomes the state illustrated in  FIG. 2 . 
     In Step S 110 , the substrate W is carried out. The controller  90  controls a power supply (not illustrated) that applies electric power to the electrode of the ESC plate  22  to release the adsorption of the substrate W by the ESC plate  22 . Then, the substrate W is carried out of the mounting surface of the holder  21  by a transport device (not illustrated). 
     When a subsequent substrate W is carried into the substrate processing apparatus  100 , the processing of the controller  90  repeats Steps S 104  to S 110 . 
     Further, in Step S 106 , when the integral value E is not greater than or equal to the threshold value E0 (S 106 : No), the process of the controller  90  proceeds to Step S 111 . In Step S 111 , the controller  90  issues a warning. 
     Here, a simulation of the temperature change when the high-temperature substrate W is placed on the holder  21  will be described with reference to  FIGS. 4 to 8 . 
       FIG. 4  is an example of a graph illustrating the temperature change when the thermal conductivity between the holder  21  and the substrate W is a reference value.  FIG. 5  is an example of a graph illustrating the temperature change when the thermal conductivity between the holder  21  and the substrate W is 50% of the reference value. 
     In  FIGS. 4 and 5 , a vertical axis represents a temperature (K), and a horizontal axis represents a time. Further, in the time on the horizontal axis, the time when the substrate W is brought into contact with the holder  21  is set to zero. A broken line indicates the temperature of the cold head  31 . An alternate long and short dash line indicates the temperature of the substrate W. Temperature curves T 1  to T 12  illustrated by solid lines indicate a temperature of each slice in which the holder  21  is sliced at predetermined intervals in a plate thickness direction. T 1  is the temperature curve in the slice on the front surface side, and T 12  is the temperature curve in the slice on the back surface side. Further, the temperature T 0  of the holder  21  and the cold head  31  before the substrate W is mounted is set to 100 K. Further, in the reference value of the thermal conductivity in  FIG. 4 , a pressure of the heat transfer gas (He gas) filling a space between the ESC plate  22  and the substrate W is set to 6 Torr. 
     When the high-temperature substrate W is placed on the holder  21 , the temperature curve T 1  of the slice closer to the substrate W shows the highest temperature increase than the temperature of the other slices. Further, the temperature curve T 12  of the slice in contact with the contact plate  37  is cooled to 100 K or less according to a heat load of the substrate W. 
       FIG. 6  is an example of a graph illustrating the temperature change of the substrate W. 
     In  FIG. 6 , a vertical axis represents a temperature (K) and a horizontal axis represents a time. Further, in the time on the horizontal axis, the time when the substrate W is brought into contact with the holder  21  is set to zero. A temperature drop of the substrate W before being in contact with the holder  21  is due to heat dissipation caused by radiant heat. Further, the pressure of the heat transfer gas (the He gas) filling the space between the ESC plate  22  and the substrate W is 2 Torr, 3 Torr, 4 Torr, or 6 Torr. 
     As illustrated in  FIG. 6 , the cooling efficiency of the substrate W is improved according to the pressure of the heat transfer gas. Further, the time required for cooling the substrate W becomes shorter as the pressure of the heat transfer gas increases. 
       FIG. 7  is an example of a graph illustrating the estimated time required to cool the substrate W. 
     In  FIG. 7 , a vertical axis represents the estimated time required to cool the substrate W from 498 K to 101 K, and a horizontal axis represents the thermal conductivity between the holder  21  and the substrate W. The horizontal axis is normalized with the thermal conductivity at the reference value as 1. 
     The thermal conductivity between the holder  21  and the substrate W depends on the pressure of the heat transfer gas (refer to  FIG. 6 ) and contact conditions between the convex portion of the ESC plate  22  and the back surface of the substrate W. For example, when a mounting position of the substrate W is displaced or particles are present between the ESC plate  22  and the substrate W, the cooling efficiency is affected. In this case, in the film forming process (Step S 107 ), the sputtered particles may be deposited at a temperature higher than a design temperature. 
     Here, it is difficult to directly measure the temperature of the substrate W. The controller  90  detects the temperature of the holder  21  and estimates the thermal conductivity between the holder  21  and the substrate W. Then, it is possible to confirm whether the substrate W is appropriately positioned and whether the substrate W and the holder  21  are appropriately in thermal contact with each other by estimating the thermal conductivity. 
     Here, as illustrated in comparison with  FIGS. 4 and 5 , the temperature of the slice of the holder  21  close to a contact surface with the substrate W rises at a different rate according to a gas conductance and a conductance between the substrate W and the holder  21 . 
     Further, the sum of products of the temperature rise of the holder  21  and the time (the integral value E in Step S 105 ) is proportional to energy required to cool the substrate W. This corresponds to an area surrounded by the temperature curve and the temperature T 0 . As an example, in  FIGS. 4 and 5 , the integral value E of the temperature change up to a predetermined time (for example, 20 seconds) on the temperature curve T 3  is shaded. Then, the temperature of each of the slices of the holder finally converges to 100 K by the refrigerating device  30 . 
       FIG. 8  is an example of a graph illustrating an increase in the integral value E. In  FIG. 8 , a vertical axis represents ΔT×Δt(=the integral value E), and a horizontal axis represents a time. Further, a case in which the thermal conductivity is the reference value (Ref), or 85%, 65%, and 50% with respect to the reference value is illustrated. 
     A curve converges around 60 seconds, but a difference in the thermal conductivity can be distinguished in a shorter time. That is, the temperature of the holder  21  is recorded over time, and the integral value E is evaluated in a short time (for example, 20 seconds) (refer to Step S 106 ). Thus, the thermal conductivity between the substrate W and the holder  21  can be evaluated without directly measuring the temperature of the substrate W. 
     Further, due to the fluorescent body  80   b  being provided in the recessed portion (in the examples of  FIGS. 4 and 5 , for example, in the slice of the temperature curve T 3 ), the temperature detection position can be brought closer to the mounting surface of the holder  21 , which is preferable. Thus, the temperature rise after the high-temperature substrate W is placed on the holder  21  can be increased, and a change in the integral value E due to the change in the thermal conductivity also becomes large. As a result, it is possible to enhance evaluation accuracy of the thermal conductivity between the substrate W and the holder  21 . 
     Further, when the integral value E calculated in Step S 105  is not higher than or equal to the threshold value E 0  (S 106 : No), an alarm can be issued assuming that the thermal conductivity between the substrate W and the holder  21  is poor (refer to Step S 111 ). Thus, in the film forming process (Step S 107 ), it is possible to prevent the sputtered particles from being deposited at a temperature higher than the design temperature. 
     Although the substrate processing apparatus has been described above according to the embodiment, the substrate processing apparatus according to the present disclosure is not limited to the above embodiment, and various modifications and improvements can be made within the scope of the present disclosure. The matters described in the above-described plurality of embodiments can be combined within a consistent range.