Patent Publication Number: US-2022212312-A1

Title: Temperature regulating apparatus and polishing apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a temperature regulating apparatus for regulating a temperature of a polishing surface of a polishing pad used for polishing a substrate, such as a wafer. The present invention further relates to a polishing apparatus including such a temperature regulating apparatus. 
     BACKGROUND ART 
     CMP (Chemical Mechanical Polishing) apparatus is used in a process of polishing a surface of a wafer in manufacturing of semiconductor devices. The CMP apparatus is configured to polish the surface of the wafer by pressing the wafer against a polishing pad on a polishing table by a polishing head while rotating the polishing table. During polishing, slurry is supplied onto the polishing pad. The surface of the wafer is planarized by a chemical action of the slurry and a mechanical action of abrasive grains contained in the slurry. 
     A polishing rate of the wafer depends not only on a polishing load on the wafer pressed against the polishing pad but also on a temperature of the polishing surface of the polishing pad. This is because the chemical action of the slurry on the wafer depends on the temperature. Therefore, in manufacturing of semiconductor devices, it is important to keep the temperature of the polishing surface of the polishing pad at an optimum value during polishing of the wafer in order to increase the polishing rate of the wafer and keep the polishing rate constant. 
     Therefore, a temperature regulating apparatus has been conventionally used to regulate the temperature of the polishing surface of the polishing pad. The temperature regulating apparatus includes a heat exchanger located above the polishing pad. During polishing of the wafer, the heat exchanger exchanges heat between the polishing pad and a fluid flowing in the heat exchanger in a state where the slurry exists between the polishing pad and the heat exchanger, thereby regulating the temperature of the polishing surface. 
     CITATION LIST 
     Patent Literature 
     Patent document 1: Japanese laid-open patent publication No. 2015-44245 
     SUMMARY OF INVENTION 
     Technical Problem 
       FIG. 12  is a schematic view showing a conventional temperature regulating apparatus, and  FIG. 13  is a cross-sectional view taken along line A-A of  FIG. 12 . As shown in  FIGS. 12 and 13 , a temperature regulating apparatus  105  includes a heat exchanger  111  having a fluid passage (not shown) formed therein, and a holder  190  arranged over the heat exchanger  111 . The heat exchanger  111  is held by the holder  190 . The heat exchanger  111  is located over a polishing surface  103   a  of a polishing pad  103 , so that a bottom surface of the heat exchanger  111  faces the polishing surface  103   a  of the polishing pad  103 . During polishing of the wafer, slurry  200  exits between the heat exchanger  111  and the polishing surface  103   a.    
     A plurality of sockets  173  (only one socket  173  is depicted in  FIG. 13 ) are fixed to an upper surface of the heat exchanger  111 . The heat exchanger  111  is fixed to the holder  190  by screwing bolts  183  into the sockets  173 , respectively, through a plurality of through-holes  190   a  of the holder  190  (only one through-hole  190   a  is depicted in  FIG. 13 ). 
     However, in the above-described fixing configuration, it is necessary to screw the plurality of bolts  183  into the plurality of sockets  173 , respectively. This results in low workability of fixing and removing the heat exchanger  111 . Moreover, it takes a long time to fix and remove the heat exchanger  111 . In addition, due to a difference in coefficient of thermal expansion between the heat exchanger  111  and the holder  190 , excessive stress may be generated in the socket  173  during polishing of the wafer, and as a result, the socket  173  may be damaged. Such excessive stress generated in the socket  173  can be a cause of low reliability of the temperature regulating apparatus  105 . 
       FIG. 14  is a schematic view showing a state in which the heat exchanger  111  is removed from the holder  190 . Each socket  173  includes a female thread  175  and an outer cylindrical body  174  into which the female thread  175  is inserted. The female thread  175  is fixed to an inner circumferential surface of the outer cylindrical body  174 , and the outer cylindrical body  174  is fixed to the upper surface of the heat exchanger  111 . 
     Since the fluid having a high temperature (for example, 60° C. to 80° C.) flows through the heat exchanger  111  during polishing of the wafer, the heat exchanger  111 , the holder  190 , the bolts  183 , and the sockets  173  thermally expand during polishing of the wafer. Typically, the holder  190 , the bolts  183 , and the female threads  175  are made of metal (e.g., stainless steel). On the other hand, the heat exchanger  111  and the outer cylindrical body  174  are formed of a material having excellent wear resistance and high thermal conductivity (e.g., ceramic, such as SiC). Due to difference in coefficient of thermal expansion between these materials, rates of change in volume of the holder  190 , the bolts  183 , and the female threads  175  during polishing of wafer are greater than rates of change in volume of the heat exchanger  111  and the outer cylindrical body  174 . As a result, during polishing of the wafer, a load is applied to the outer cylindrical body  174  from the bolts  183  and the female threads  175 , and the outer cylindrical body  174  may be damaged. 
     Therefore, an object of the present invention is to provide a temperature regulating apparatus which improves workability in fixing and removing a heat exchanger and has excellent reliability. Another object of the present invention is to provide a polishing apparatus including such a temperature regulating apparatus. 
     Solution to Problem 
     In an embodiment, there is provided a temperature regulating apparatus for regulating a temperature of a polishing surface of a polishing pad, comprising: a heat exchanger having a heating flow passage and a cooling flow passage formed therein; a holder arranged over the heat exchanger; a coupling mechanism configured to detachably fix the heat exchanger to the holder, the coupling mechanism including: a first hook fixed to an upper surface of the heat exchanger; and a second hook held by the holder, the second hook being configured to be able to be engaged with and disengaged from the first hook. 
     In an embodiment, the first hook includes: a first base fixed to the upper surface of the heat exchanger; and a first protrusion protruding laterally from the first base, the second hook includes: a second base extending through the holder; and a second protrusion protruding laterally from the second base, the second protrusion being configured to be able to contact a lower surface of the first protrusion. 
     In an embodiment, the second hook is rotatable about its own axis. 
     In an embodiment, the coupling mechanism further includes: a screw arranged in the first hook; and a spiral structure embedded in the heat exchanger, the screw being screwed into the spiral structure through a through-hole formed in the first hook. 
     In an embodiment, the coupling mechanism further includes a coil spring into which the second base is inserted, the coil spring being arranged on an upper surface of the holder. 
     In an embodiment, the holder has a housing chamber in which the first hook and the second hook are arranged. 
     In an embodiment, the second hook is arranged outwardly of the first hook in a radial direction of the heat exchanger. 
     In an embodiment, the second hook comprises two second hooks, the two second hooks being arranged on both sides of the first hook in a circumferential direction of the heat exchanger. 
     In an embodiment, the coupling mechanism comprises a plurality of coupling mechanisms arranged in a circumferential direction of the heat exchanger. 
     In an embodiment, the heat exchanger has a side surface composed of a water-repellent coating layer. 
     In an embodiment, there is provided a polishing apparatus comprising: a polishing table configured to support a polishing pad; a polishing head configured to press a substrate against a polishing surface of the polishing pad; and the temperature regulating apparatus configured to regulate a temperature of the polishing surface by exchanging heat with the polishing pad. 
     Advantageous Effects of Invention 
     According to the present invention, the heat exchanger is fixed to the holder by the engagement between the first hook fixed to the upper surface of the heat exchanger and the second hook held by the holder. Further, the heat exchanger can be removed from the holder by disengaging the second hook from the first hook. As a result, the workability in fixing and removing the heat exchanger can be improved. 
     Further, according to the above-described configuration, the engagement between the first hook and the second hook can allow mutual displacement of these hooks to some degree, as compared with the conventional engagement between the bolt and the female thread. Specifically, the second hook can be displaced relative to the first hook while maintaining engagement with the first hook. Therefore, the combination of the first hook and the second hook can relieve a stress that may be generated in the first hook during polishing of the substrate. As a result, the reliability of the temperature regulating apparatus can be improved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic view showing an embodiment of a polishing apparatus including a temperature regulating apparatus; 
         FIG. 2  is a horizontal cross-sectional view showing a heat exchanger; 
         FIG. 3  is a plan view showing a positional relationship between the heat exchanger and a polishing head on a polishing pad; 
         FIG. 4  is a schematic view showing an embodiment of a method of fixing the heat exchanger to a holder; 
         FIG. 5  is a cross-sectional view taken along line B-B of  FIG. 4 ; 
         FIG. 6  is a schematic view showing a state in which the heat exchanger is removed from the holder; 
         FIG. 7  is a schematic view showing an embodiment of a method of fixing a first hook; 
         FIG. 8  is a schematic view showing a state in which the first hook of  FIG. 7  is removed from the heat exchanger; 
         FIG. 9  is a schematic view showing another embodiment of a coupling mechanism; 
         FIG. 10  is a schematic view showing another embodiment of a method of fixing the heat exchanger; 
         FIG. 11  is a cross-sectional view taken along line C-C of  FIG. 10 ; 
         FIG. 12  is a schematic diagram showing a conventional temperature regulating apparatus; 
         FIG. 13  is a cross-sectional view taken along line A-A of  FIG. 12 ; and 
         FIG. 14  is a schematic view showing a state in which a heat exchanger is removed from a holder. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. 
       FIG. 1  is a schematic view showing an embodiment of a polishing apparatus including a temperature regulating apparatus. As shown in  FIG. 1 , a polishing apparatus  10  includes a polishing head  1  configured to hold and rotate a wafer W (which is an example of a substrate), a polishing table  2  for supporting a polishing pad  3 , a slurry supply nozzle  4  configured to supply slurry onto a surface of the polishing pad  3 , and a temperature regulating apparatus  5  configured to regulate a temperature of a polishing surface  3   a  of the polishing pad  3 . The surface (upper surface) of the polishing pad  3  constitutes the polishing surface  3   a  for polishing the wafer W. 
     The polishing head  1  is movable in a vertical direction and is rotatable about an axis thereof in a direction indicated by arrow. The wafer W is held on a lower surface of the polishing head  1  by vacuum suction or the like. A table motor  6  is coupled to the polishing table  2 , so that the polishing table  2  can rotate in a direction indicated by arrow. As shown in  FIG. 1 , the polishing head  1  and the polishing table  2  rotate in the same direction. The polishing pad  3  is attached to an upper surface of the polishing table  2 . 
     The polishing apparatus  10  includes an operation controller  40  configured to control operations of the polishing head  1 , the table motor  6 , the slurry supply nozzle  4 , and the temperature regulating apparatus  5 . The operation controller  40  is composed of at least one computer. The operation controller  40  includes a memory  40   a  and an arithmetic device  40   b.  The arithmetic device  40   b  includes a CPU (central processing unit) or a GPU (graphic processing unit) configured to perform arithmetic operations according to instructions included in programs stored in the memory  40   a.  The memory  40   a  includes a main memory (for example, a random-access memory) to which the arithmetic device  40   b  is accessible, and an auxiliary memory (for example, a hard disk drive or a solid state drive) for storing data and programs. 
     Polishing of the wafer W is performed as follows. The wafer W to be polished is held by the polishing head  1  and rotated by the polishing head  1 . The polishing table  2  is rotated by the table motor  6  together with the polishing pad  3 . In this state, the slurry is supplied from the slurry supply nozzle  4  onto the polishing surface  3   a  of the polishing pad  3 , and the surface of the wafer W is pressed against the polishing surface  3   a  of the polishing pad  3  by the polishing head  1 . The surface of the wafer W is polished by sliding contact with the polishing pad  3  in the presence of the slurry. The surface of the wafer W is planarized by the chemical action of the slurry and the mechanical action of the abrasive grains contained in the slurry. 
     The temperature regulating apparatus  5  includes a heat exchanger  11  configured to regulate the temperature of the polishing surface  3   a  by exchanging heat with the polishing pad  3 , a holder  90  arranged over the heat exchanger  11 , a fluid supply system  30  configured to supply a heating fluid and a cooling fluid, each having a controlled temperature, to the heat exchanger  11 , and an elevating mechanism  20  coupled to the heat exchanger  11 . The heat exchanger  11  is located over the polishing surface  3   a  of the polishing table  2  and the polishing pad  3 . 
     The heat exchanger  11  has a bottom surface facing the polishing surface  3   a  of the polishing pad  3 , and the heat exchanger  11  is held by the holder  90 . The heat exchanger  11  and holder  90  as a whole have a cylindrical shape. The bottom surface of the heat exchanger  11  is flat and circular. In this embodiment, the heat exchanger  11  and the holder  90  are made of different materials. More specifically, the holder  90  is made of metal (for example, stainless steel), while the heat exchanger  11  is made of a material having excellent wear resistance and high thermal conductivity (for example, ceramic, such as SiC). 
     The holder  90  has a circular upper surface. The holder  90  is fixed to an arm  22  and is coupled to the elevating mechanism  20  via the arm  22 . The elevating mechanism  20  is configured to raise and lower the heat exchanger  11  and the holder  90 . More specifically, the elevating mechanism  20  is configured to move the bottom surface of the heat exchanger  11  in a direction closer to the polishing surface  3   a  of the polishing pad  3  and in a direction away from the polishing surface  3   a  of the polishing pad  3 . The elevating mechanism  20  includes an actuator (not shown), such as a motor or an air cylinder. The operation of the elevating mechanism  20  is controlled by the operation controller  40 . 
     The fluid supply system  30  includes a heating-fluid supply tank  31  as a heating-fluid supply source for storing the temperature-controlled heating fluid, and a heating-fluid supply pipe  32  and a heating-fluid return pipe  33  coupling the heating-fluid supply tank  31  to the heat exchanger  11 . Ends of the heating-fluid supply pipe  32  and the heating-fluid return pipe  33  are coupled to the heating-fluid supply tank  31 , and the other ends are coupled to the heat exchanger  11 . 
     The heating fluid having a controlled temperature is supplied from the heating-fluid supply tank  31  to the heat exchanger  11  through the heating-fluid supply pipe  32 , flows through the heat exchanger  11 , and is returned to the heating-fluid supply tank  31  from the heat exchanger  11  through the heating-fluid return pipe  33 . In this way, the heating fluid circulates between the heating-fluid supply tank  31  and the heat exchanger  11 . The heating-fluid supply tank  31  has a heater (not shown), so that the heating fluid is heated to a predetermined temperature by the heater. 
     The fluid supply system  30  further includes a first on-off valve  41  and a first flow-rate control valve  42  attached to the heating-fluid supply pipe  32 . The first flow-rate control valve  42  is arranged between the heat exchanger  11  and the first on-off valve  41 . The first on-off valve  41  is a valve that does not have a flow rate regulating function, while the first flow-rate control valve  42  is a valve that has a flow rate regulating function. 
     The fluid supply system  30  further includes a cooling-fluid supply pipe  51  and a cooling-fluid discharge pipe  52 , both of which are coupled to the heat exchanger  11 . The cooling-fluid supply pipe  51  is coupled to a cooling-fluid supply source (for example, a cold-water supply source) provided in a factory where the polishing apparatus  10  is installed. The cooling fluid is supplied to the heat exchanger  11  through the cooling-fluid supply pipe  51 , flows through the heat exchanger  11 , and is discharged from the heat exchanger  11  through the cooling-fluid discharge pipe  52 . In one embodiment, the cooling fluid that has flowed through the heat exchanger  11  may be returned to the cooling-fluid supply source through the cooling-fluid discharge pipe  52 . 
     The fluid supply system  30  further includes a second on-off valve  55  and a second flow-rate control valve  56  attached to the cooling-fluid supply pipe  51 . The second flow-rate control valve  56  is arranged between the heat exchanger  11  and the second on-off valve  55 . The second on-off valve  55  is a valve that does not have a flow rate regulating function, while the second flow-rate control valve  56  is a valve that has a flow rate regulating function. 
     The first on-off valve  41 , the first flow-rate control valve  42 , the second on-off valve  55 , and the second flow-rate control valve  56  are coupled to the operation controller  40 , so that the operations of the first on-off valve  41 , the first flow-rate control valve  42 , the second on-off valve  55 , and the second flow-rate control valve  56  are controlled by the operation controller  40 . 
     The temperature regulating apparatus  5  further includes a pad temperature measuring device  39  for measuring the temperature of the polishing surface  3   a  of the polishing pad  3  (which may be referred to as pad surface temperature). The pad temperature measuring device  39  is coupled to the operation controller  40 . The operation controller  40  is configured to operate the first flow-rate control valve  42  and the second flow-rate control valve  56  based on the pad surface temperature measured by the pad temperature measuring device  39 . The first on-off valve  41  and the second on-off valve  55  are normally open. The pad temperature measuring device  39  may be a radiation thermometer capable of measuring the temperature of the polishing surface  3   a  of the polishing pad  3  in a non-contact manner. The pad temperature measuring device  39  is arranged above the polishing surface  3   a.    
     The pad temperature measuring device  39  measures the pad surface temperature in a non-contact manner and sends a measured value of the pad surface temperature to the operation controller  40 . The operation controller  40  operates the first flow-rate control valve  42  and the second flow-rate control valve  56  to control the flow rates of the heating fluid and the cooling fluid based on the measured pad surface temperature so that the pad surface temperature is maintained at a preset target temperature. The first flow-rate control valve  42  and the second flow-rate control valve  56  operate according to control signals from the operation controller  40  to regulate the flow rate of the heating fluid and the flow rate of the cooling fluid to be supplied to the heat exchanger  11 . The heat exchange is performed between the heating and cooling fluids flowing through the heat exchanger  11  and the polishing pad  3 . As a result, the pad surface temperature changes. 
     By such feedback control, the temperature of the polishing surface  3   a  of the polishing pad  3  (i.e., the pad surface temperature) is maintained at a predetermined target temperature. PID control can be used as the feedback control. The target temperature of the polishing pad  3  is determined based on a type of film constituting the surface of the wafer W or a polishing process. The determined target temperature is input in advance to the operation controller  40  and stored in the memory  40   a.    
     The heating fluid to be supplied to the heat exchanger  11  may be a heating liquid, such as hot water. The heating fluid is heated to, for example, about 80° C. by the heater (not shown) of the heating-fluid supply tank  31 . In order to raise the surface temperature of the polishing pad  3  more quickly, silicone oil may be used as the heating fluid. When the silicone oil is used as the heating fluid, the silicone oil is heated to 100° C. or higher (for example, about 120° C.) by the heater of the heating-fluid supply tank  31 . The cooling fluid to be supplied to the heat exchanger  11  may be a cooling liquid, such as cold water or silicone oil. When silicone oil is used as the cooling fluid, a chiller as the cooling-fluid supply source may be coupled to the cooling-fluid supply pipe  51 , and the silicone oil may be cooled to 0° C. or lower by the chiller, so that the polishing pad  3  can be quickly cooled. Pure water can be used as the cold water. In order to cool the pure water to produce the cold water, a chiller may be used as the cooling-fluid supply source. In this case, the cold water that has flown through the heat exchanger  11  may be returned to the chiller through the cooling-fluid discharge pipe  52 . 
     The heating-fluid supply pipe  32  and the cooling-fluid supply pipe  51  are completely independent pipes. Therefore, the heating fluid and the cooling fluid are simultaneously supplied to the heat exchanger  11  without being mixed. The heating-fluid return pipe  33  and the cooling-fluid discharge pipe  52  are also completely independent pipes. Therefore, the heating fluid is returned to the heating-fluid supply tank  31  without being mixed with the cooling fluid, and the cooling fluid is discharged or returned to the cooling-fluid supply source without being mixed with the heating fluid. 
     The temperature regulating apparatus  5  further includes a plurality of cleaning nozzles  60  for cleaning the heat exchanger  11  by spraying pure water onto the side surface of the heat exchanger  11 . These cleaning nozzles  60  are oriented toward the side surface of the heat exchanger  11 . In the present embodiment, two cleaning nozzles  60  are provided, but three or more cleaning nozzles  60  may be provided. Each cleaning nozzle  60  emits a jet of pure water to remove the slurry that has been used in polishing of the wafer W from the side surface of the heat exchanger  11 . 
     Next, the heat exchanger  11  will be described with reference to  FIG. 2 .  FIG. 2  is a horizontal cross-sectional view showing the heat exchanger  11 . As shown in  FIG. 2 , the heat exchanger  11  includes a flow-passage structure  70 . A heating flow passage  61  and a cooling flow passage  62  are formed in the flow-passage structure  70 . The heating flow passage  61  and the cooling flow passage  62  extend adjacent to each other (i.e., side by side) and extend spirally. Further, the heating flow passage  61  and the cooling flow passage  62  have a point-symmetrical shape and have the same length. Each of the heating flow passage  61  and the cooling flow passage  62  is basically composed of a plurality of arc flow passages  64  having a constant curvature and a plurality of inclined flow passages  65  coupling the arc flow passages  64 . Two adjacent arc flow passages  64  are coupled by each inclined flow passage  65 . 
     According to such configurations, outermost peripheral portions of the heating flow passage  61  and the cooling flow passage  62  can be arranged at the outermost peripheral portion of the heat exchanger  11 . Specifically, the entire bottom surface of the heat exchanger  11  is located below the heating flow passage  61  and the cooling flow passage  62 , so that the heating fluid and the cooling fluid can quickly heat and cool the polishing surface  3   a  of the polishing pad  3 . The heat exchange between the heating and cooling fluids and the polishing pad  3  is performed in the presence of the slurry (not shown) between the polishing surface  3   a  of the polishing pad  3  and the bottom surface of the flow-passage structure  70  (i.e., the bottom surface of the heat exchanger  11 ). 
     The heating-fluid supply pipe  32  (see  FIG. 1 ) is coupled to an inlet  61   a  of the heating flow passage  61 , and the heating-fluid return pipe  33  (see  FIG. 1 ) is coupled to an outlet  61   b  of the heating flow passage  61 . The cooling-fluid supply pipe  51  (see  FIG. 1 ) is coupled to an inlet  62   a  of the cooling flow passage  62 , and the cooling-fluid discharge pipe  52  (see  FIG. 1 ) is coupled to an outlet  62   b  of the cooling flow passage  62 . The heating-fluid supply pipe  32 , the heating-fluid return pipe  33 , the cooling-fluid supply pipe  51 , and the cooling-fluid discharge pipe  52  are coupled to the inlet  61   a,  the outlet  61   b,  the inlet  62   a,  and the outlet  62   b,  respectively, via the holder  90  (see  FIG. 1 ). 
     The inlets  61   a  and  62   a  of the heating flow passage  61  and the cooling flow passage  62  are located at the peripheral portion of the heat exchanger  11 , and the outlets  61   b  and  62   b  of the heating flow passage  61  and the cooling flow passage  62  are located at the central portion of the heat exchanger  11 . Therefore, the heating fluid and the cooling fluid spirally flow from the peripheral portion to the central portion of the heat exchanger  11 . The heating flow passage  61  and the cooling flow passage  62  are completely separated, and the heating fluid and the cooling fluid are not mixed in the heat exchanger  11 . 
       FIG. 3  is a plan view showing a positional relationship between the heat exchanger  11  and the polishing head  1  on the polishing pad  3 . In  FIG. 3 , the holder  90  is not shown. The heat exchanger  11  is circular when viewed from above, and the diameter of the heat exchanger  11  is smaller than the diameter of the polishing head  1 . A distance from a rotation center O of the polishing pad  3  to a center P of the heat exchanger  11  is the same as a distance from the rotation center O of the polishing pad  3  to a center Q of the polishing head  1 . Since the heating flow passage  61  and the cooling flow passage  62  are adjacent to each other, the heating flow passage  61  and the cooling flow passage  62  are arranged not only along the radial direction of the polishing pad  3  but also along the circumferential direction of the polishing pad  3 . Therefore, while the polishing table  2  and the polishing pad  3  are rotating, the polishing pad  3  exchanges heat with both the heating fluid and the cooling fluid. The two cleaning nozzles  60  are arranged at both sides of the heat exchanger  11 . 
       FIG. 4  is a schematic view showing an embodiment of a method of fixing the heat exchanger  11  to the holder  90 , and  FIG. 5  is a cross-sectional view taken along line B-B of  FIG. 4 .  FIG. 5  shows a state when the holder  90  holds the heat exchanger  11 . In  FIG. 5 , the heating flow passage  61  and the cooling flow passage  62  are not shown. As shown in  FIGS. 4 and 5 , the temperature regulating apparatus  5  further includes a plurality of coupling mechanisms  80  configured to detachably fix the heat exchanger  11  to the holder  90 . As shown in  FIG. 4 , the plurality of coupling mechanisms  80  are arranged along the circumferential direction of the heat exchanger  11  over the entire circumference of the heat exchanger  11 . In one embodiment, the plurality of coupling mechanisms  80  may be arranged at equal intervals in the circumferential direction of the heat exchanger  11 . 
     As shown in  FIG. 5 , each coupling mechanism  80  has a first hook  73  fixed to the upper surface of the heat exchanger  11  (i.e., the upper surface of the flow-passage structure  70 ) and a second hook  83  held by the holder  90 . The second hook  83  is configured to be engageable with and detachable from the first hook  73 . The holder  90  has a housing chamber  85  in which the first hook  73  and the second hook  83  are arranged. When the holder  90  holds the heat exchanger  11 , the entire first hook  73  and a part of the second hook  83  are located in the housing chamber  85 . 
     More specifically, the first hook  73  includes a first base  73   a  fixed to the upper surface of the heat exchanger  11  and a first protrusion  73   b  protruding laterally from the first base  73   a.  The second hook  83  includes a second base  83   a  extending through the holder  90 , and a second protrusion  83   b  protruding laterally from the second base  83   a.  The second base  83   a  extends through a through-hole  90   a  of the holder  90 . The second protrusion  83   b  is configured to be able to contact a lower surface of the first protrusion  73   b.  When the holder  90  holds the heat exchanger  11  (i.e., when the first hook  73  and the second hook  83  are in engagement), an upper surface of the second protrusion  83   b  is in contact with the lower surface of the first protrusion  73   b.    
       FIG. 6  is a schematic view showing a state in which the heat exchanger  11  is removed from the holder  90 . The second hook  83  is configured to be rotatable about an axis R extending in parallel with the second base  83   a.  By rotating the second hook  83  about the axis R, the second hook  83  can be disengaged from the first hook  73 . When all the second hooks  83  are disengaged from the first hooks  73 , the heat exchanger  11  can be removed from the holder  90 . 
     Similarly, by rotating the second hook  83  about the axis R until the upper surface of the second protrusion  83   b  contacts the lower surface of the first protrusion  73   b,  with the upper surface of the heat exchanger  11  pressed against the lower surface of the holder  90 , the second hook  83  and the first hook  73  can be engaged with each other, so that the heat exchanger  11  can be fixed to the holder  90 . By engaging all the second hooks  83  with all the first hooks  73 , respectively, the heat exchanger  11  is securely fixed to the holder  90 . 
     As described above, in the present embodiment, the heat exchanger  11  is fixed to the holder  90  by the engagement between the first hooks  73 , which are fixed to the upper surface of the heat exchanger  11 , and the second hooks  83  held by the holder  90 . Further, the heat exchanger  11  can be removed from the holder  90  by disengaging the second hooks  83  from the first hooks  73 . In this manner, the heat exchanger  11  can be fixed and removed with simple operations, which improve the workability in fixing and removing the heat exchanger  11 . Further, since a variation in work by an operator can be suppressed, the heat exchanger  11  can be stably fixed and removed. 
     During polishing of the wafer W, the fluid with a high temperature (for example, 60° C. to 80° C.) flows through the heat exchanger  11 . As a result, the flow-passage structure  70 , the holder  90 , and the coupling mechanisms  80  thermally expand. As described above, in the present embodiment, the holder  90  is made of metal (for example, stainless steel), and the flow-passage structure  70  is made of material having excellent wear resistance and high thermal conductivity (for example, ceramic, such as SiC). 
     The first hooks  73  are made of metal (for example, stainless steel). The second hooks  83  are made of resin material. In one embodiment, the first hooks  73  may be made of ceramic, such as SiC, and the second hook  83  may be made of metal, such as stainless steel. 
     According to the configurations of the present embodiment, the engagement of the first hooks  73  and the second hooks  83  allows mutual displacement to some degree as compared with the engagement of the conventional bolts and female threads. Specifically, the second hooks  83  can be displaced relative to the first hooks  73  while maintaining the engagement with the first hooks  73 . Therefore, the combination of the first hooks  73  and the second hooks  83  can relieve stress that may be generated in the first hooks  73  during polishing of the wafer W. As a result, the reliability of the temperature regulating apparatus  5  can be improved. 
     As shown in  FIGS. 5 and 6 , the heat exchanger  11  further includes a water-repellent coating layer  91  provided on the side surface of the flow-passage structure  70 . The side surface of the heat exchanger  11  is composed of the water-repellent coating layer  91 . As shown in  FIG. 5 , the slurry  7  is present between the heat exchanger  11  and the polishing surface  3   a  during polishing of the wafer W, and the slurry  7  may be attached to a surface of the coating layer  91  during polishing of the wafer W. According to this embodiment, the slurry  7  attached to the surface of the coating layer  91  gathers during polishing of the wafer W, and the volume thereof increases. As a result, the slurry  7  is less likely to dry, and the slurry  7  is prevented from sticking to the side surface of the heat exchanger  11  during polishing of the wafer W. 
     Examples of the coating layer  91  include a film made of polytetrafluoroethylene. Polytetrafluoroethylene is known as Teflon (registered trademark). Forming of the coating layer  91  is performed in a high temperature environment (for example, 100° C. to 400° C.) before the heat exchanger  11  is attached to the holder  90 . If the coating layer  91  is peeled off as the heat exchanger  11  is used, it is necessary to form the coating layer  91  again. 
     In the conventional configurations shown in  FIG. 14 , the socket  173  includes the female thread  175  and the outer cylindrical body  174  composed of different materials. Therefore, when the coating layer is peeled off and the heat exchanger  111  is exposed to a high temperature in the step of forming the coating layer again, the female thread  175  may thermally expand more larger than the outer cylindrical body  174 , thus causing damage to the outer cylindrical body  174 . In contrast, the first hook  73  is made of a single material, and therefore, excessive stress is not generated in the first hook  73  even when the first hook  73  thermally expands. Therefore, if the coating layer  91  is peeled off, the heat exchanger  11  is removed from the holder  90 , and the coating layer  91  can be formed again. As a result, the flow-passage structure  70  and the first hooks  73  can be reused, and the manufacturing cost of the temperature regulating apparatus  5  can be reduced. In one embodiment, the coating layer  91  may be provided on the bottom surface of the flow-passage structure  70 . 
     As shown in  FIGS. 4 and 5 , the second hooks  83  are arranged outwardly of the first hooks  73  in the radial directions of the heat exchanger  11 . In the present embodiment, due to a difference in coefficient of thermal expansion between materials, a rate of change in the volume of the holder  90  holding the second hooks  83  is larger than a rate of change in the volume of the flow-passage structure  70  to which the first hooks  73  are fixed during polishing of the wafer W. Therefore, the second hooks  83  are displaced in the direction away from the first hooks  73  during polishing of the wafer W. 
     The above-described arrangement of the second hooks  83  with respect to the first hooks  73  can prevent lateral loads from being applied from the second hooks  83  to the first hooks  73  when the temperatures of the flow-passage structure  70  and the holder  90  rise. As a result, the reliability of the temperature regulating apparatus  5  can be further improved. 
       FIG. 7  is a schematic view showing an embodiment of a method of fixing the first hook  73  to the heat exchanger  11 , and  FIG. 8  is a schematic view showing a state in which the first hook  73  of  FIG. 7  is removed from the heat exchanger  11 . In  FIGS. 7 and 8 , the second hook  83 , the holder  90 , the heating flow passage  61 , and the cooling flow passage  62  are not shown. As shown in  FIGS. 7 and 8 , the coupling mechanism  80  further includes a screw  75  arranged in the first hook  73 , and a spiral structure  77  embedded in the heat exchanger  11  (i.e., in the flow-passage structure  70 ). The screw  75  is screwed into the spiral structure  77  through a through-hole  73   c  formed in the first hook  73 . 
     The screw  75  and the spiral structure  77  are made of metal (e.g., stainless steel). The spiral structure  77  comprises a spiral coil. The spiral structure  77  is available on the market as helicoid insert or helical insert. According to such configurations, since the spiral structure  77  has a small amount of change in thermal expansion, excessive load is not applied from the spiral structure  77  to the heat exchanger  11  even when the temperature of the heat exchanger  11  rises during polishing of the wafer W and re-forming of the coating layer  91 . As a result, generation of excessive stress in the heat exchanger  11  is prevented. 
       FIG. 9  is a schematic view showing another embodiment of the coupling mechanism  80 . The details of the present embodiment, which are not particularly described, are the same as those of the embodiments described with reference to  FIGS. 1 to 6 , and thus the duplicate descriptions thereof will be omitted. The coupling mechanism  80  of the present embodiment further includes a coil spring  87  into which the second base  83   a  is inserted. The coil spring  87  is arranged on the upper surface of the holder  90 . When the second hook  83  and the first hook  73  are in engagement, an upward force indicated by an arrow in  FIG. 9  is applied from the coil spring  87  to a head portion  83   c  of the second hook  83 . Specifically, the second hook  83  is pushed upward by the coil spring  87 , so that an upward force is applied from the second protrusion  83   b  of the second hook  83  to the first protrusion  73   b  of the first hook  73 . As a result, the heat exchanger  11  is more securely fixed to the holder  90 . The embodiment described with reference to  FIGS. 7 and 8  may be applied to the present embodiment described with reference to  FIG. 9 . 
       FIG. 10  is a schematic view showing another embodiment of a method of fixing the heat exchanger  11 , and  FIG. 11  is a cross-sectional view taken along line C-C of  FIG. 10 . The details of the present embodiment, which are not particularly described, are the same as those of the embodiments described with reference to  FIGS. 1 to 6 , and thus the duplicate descriptions thereof will be omitted. As shown in  FIGS. 10 and 11 , each coupling mechanism  80  of the present embodiment includes two second hooks  83 . The two second hooks  83  are arranged on both sides of the first hook  73  in the circumferential direction of the heat exchanger  11 . 
     In this embodiment, since the two second hooks  83  can be engaged with one first hook  73 , the heat exchanger  11  can be more reliably fixed to the holder  90 . Further, since the two second hooks  83  are arranged on both sides of the first hook  73  in the circumferential direction of the heat exchanger  11 , a lateral load is not applied from the second hooks  83  to the first hook  73  even when the temperatures of the flow-passage structure  70  and the holder  90  rise during polishing of the wafer W. As a result, the reliability of the temperature regulating apparatus  5  can be further improved. The embodiment described with reference to  FIGS. 7 to 9  may be applied to the present embodiment described with reference to  FIGS. 10 and 11 . 
     The previous description of embodiments is provided to enable a person skilled in the art to make and use the present invention. Moreover, various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles and specific examples defined herein may be applied to other embodiments. Therefore, the present invention is not intended to be limited to the embodiments described herein but is to be accorded the widest scope as defined by limitation of the claims. 
     INDUSTRIAL APPLICABILITY 
     The present invention is applicable to a temperature regulating apparatus for regulating a temperature of a polishing surface of a polishing pad used for polishing a substrate, such as a wafer. Further, the present invention is applicable to a polishing apparatus including such a temperature regulating apparatus. 
     REFERENCE SIGNS LIST 
     
         
           1  polishing head 
           2  polishing table 
           3  polishing pad 
           4  slurry supply nozzle 
           5  temperature regulating apparatus 
           6  table motor 
           7  slurry 
           10  polishing apparatus 
           11  heat exchanger 
           20  elevating mechanism 
           22  arm 
           30  fluid supply system 
           31  heating-fluid supply tank 
           32  heating-fluid supply pipe 
           33  heating-fluid return pipe 
           39  pad temperature measuring device 
           40  operation controller 
           41  first on-off valve 
           42  first flow-rate control valve 
           51  cooling-fluid supply pipe 
           52  cooling-fluid discharge pipe 
           55  second on-off valve 
           56  second flow-rate control valve 
           60  cleaning nozzle 
           61  heating flow passage 
           62  cooling flow passage 
           64  arc flow passage 
           65  inclined flow passage 
           70  flow-passage structure 
           73  first hook 
           73   a  first base 
           73   b  first protrusion 
           75  screw 
           77  spiral structure 
           80  coupling mechanism 
           83  second hook 
           83   a  second base 
           83   b  second protrusion 
           83   c  head portion 
           85  housing chamber 
           87  coil spring 
           90  holder 
           90   a  through-hole 
           91  coating layer 
           103  polishing pad 
           105  temperature regulating apparatus 
           111  heat exchanger 
           173  socket 
           174  outer cylindrical body 
           175  female thread 
           183  bolt 
           190  holder 
           200  slurry