Patent Publication Number: US-2020294775-A1

Title: Plasma processing apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2019-046237, filed on Mar. 13, 2019, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     Various aspects and embodiments of the present disclosure relate to a plasma processing apparatus. 
     BACKGROUND 
     In a film formation process using plasma, a plasma generation space in which plasma is generated and a processing space in which a workpiece is processed may be separated for the purpose of reducing ion damage to the workpiece and improving step coverage. The plasma generation space and the processing space are separated using, for example, a plate having a plurality of through holes. Therefore, the ions contained in the plasma generated in the plasma generation space are hindered from infiltrating into the processing space by the plate, and thus damage to the workpiece by the ions is reduced. In addition, since the active species contained in the plasma are supplied to the workpiece through the holes in the plate, it is possible to perform film formation mainly using the active species, and thus improve step coverage. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Japanese Laid-Open Patent Publication No. H11-168094 
     SUMMARY 
     According to embodiments of the present disclosure, there is provided a plasma processing apparatus including a gas supply configured to supply a gas into a plasma generation chamber; a first power supply configured to convert the gas supplied into the plasma generation chamber into plasma by supplying a first high-frequency power into the plasma generation chamber; a separation plate configured to separate the plasma generation chamber and a processing chamber below the plasma generation chamber, the separation plate having a plurality of through holes so as to guide active species contained in the plasma generated in the plasma generation chamber to the processing chamber; and a temperature controller having a flow path through which a fluid flows in a temperature-controlled manner, the temperature controller being configured to control a temperature of the separation plate through heat exchange with the fluid. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure. 
         FIG. 1  is a schematic cross-sectional view illustrating an exemplary plasma processing apparatus in a first embodiment of the present disclosure. 
         FIG. 2  is a plan view illustrating an exemplary cooling plate in a first embodiment of the present disclosure. 
         FIG. 3  is a cross-sectional view illustrating the exemplary cooling plate in the first embodiment of the present disclosure, taken along line A-A. 
         FIG. 4  is a cross-sectional view illustrating the exemplary cooling plate in the first embodiment of the present disclosure, taken along line B-B. 
         FIG. 5  is a cross-sectional view illustrating an exemplary cooling plate in a second embodiment of the present disclosure, taken along line A-A. 
         FIG. 6  is a cross-sectional view illustrating the exemplary cooling plate in the embodiment of the present disclosure, taken along line B-B. 
         FIG. 7  is a cross-sectional view illustrating an exemplary cooling plate in a third embodiment of the present disclosure. 
         FIG. 8  is a plan view illustrating an exemplary cooling plate in a fourth embodiment of the present disclosure. 
         FIG. 9  is a cross-sectional view illustrating the exemplary cooling plate in the fourth embodiment of the present disclosure, taken along line A 1 -A 1 . 
         FIG. 10  is a cross-sectional view illustrating the exemplary cooling plate in the fourth embodiment of the present disclosure, taken along line A 2 -A 2 . 
         FIG. 11  is a cross-sectional view illustrating the exemplary cooling plate in the fourth embodiment of the present disclosure, taken along line B-B. 
         FIG. 12  is a cross-sectional view illustrating an exemplary cooling plate in a fifth embodiment of the present disclosure. 
         FIG. 13  is a schematic cross-sectional view illustrating an exemplary cooling plate in a sixth embodiment of the present disclosure. 
         FIG. 14  is a schematic cross-sectional view illustrating an exemplary cooling plate in a seventh embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, systems, and components have not been described in detail so as not to unnecessarily obscure aspects of the various embodiments. 
     A separation plate, which separates a plasma generation space and a processing space is heated by the plasma generated in the plasma generation space. When the separation plate is excessively heated, the separation plate may be deformed or broken by the stress generated by a thermal gradient. Therefore, it is necessary to suppress the temperature rise of the separation plate. 
     Therefore, the present disclosure provides a technology capable of suppressing a rise in the temperature of the separation plate. 
     First Embodiment 
     [Configuration of Plasma Processing Apparatus  1 ] 
       FIG. 1  is a schematic cross-sectional view illustrating an exemplary plasma processing apparatus  1  in a first embodiment of the present disclosure. The plasma processing apparatus  1  is, for example, a parallel-plate capacitively coupled plasma atomic layer deposition (ALD) apparatus. The plasma processing apparatus  1  includes an apparatus body  2  and a control device  3 . The apparatus body  2  includes a processing container  10  formed of, for example, aluminum having an anodized surface, and having a substantially cylindrical space formed therein. The processing container  10  may be formed of pure aluminum or aluminum sprayed with ceramics or the like. The processing container  10  is grounded. 
     A stage  13  on which a wafer W is placed is provided in the processing container  10 . The stage  13  is formed of, for example, ceramics, aluminum, or a combination thereof, and is supported by a support member  14 . An electrode  130  is provided in the stage  13 . A DC power supply  132  is connected to the electrode  130  via a switch  131 . The wafer W is placed on the upper surface of the stage  13 , and is attracted and held on the upper surface of the stage  13  by an electrostatic force generated on the surface of the stage  13  by a DC voltage supplied from the DC power supply  132  to the electrode  130  via the switch  131 . Within the stage  13 , a temperature control mechanism including a heater (not illustrated) and a flow path through which a coolant flows, is provided. 
     An edge ring  133  formed of, for example, ceramics is provided on the upper surface of the stage  13 . The edge ring  133  is sometimes called a focus ring. The edge ring  133  improves the uniformity of plasma processing on the surface of the wafer W. Instead of the edge ring  133 , the upper surface portion of the stage  13  on which the wafer W is placed may have a pocket shape engraved along the shape of the wafer W. 
     An opening  15  is provided in the side wall of the processing container  10 , and the opening  15  is opened/closed by a gate valve G. An exhaust port  40  is provided in the bottom portion of the processing container  10 . An exhaust device  42  is connected to the exhaust port  40  via a pressure adjustment valve  41 . By driving the exhaust device  42 , the gas in the processing container  10  is exhausted through the exhaust port  40 , and by adjusting the degree of opening of the pressure adjustment valve  41 , the pressure in the processing container  10  is adjusted. 
     A substantially disk-shaped electrode  30  is provided above the stage  13 . The electrode  30  is supported on the upper portion of the processing container  10  via an insulating member  16  such as ceramics. The electrode  30  is formed of a conductive metal such as aluminum (Al) or nickel (Ni). 
     A gas supply pipe  54   a  is connected to the electrode  30 , and the gas supplied through the gas supply pipe  54   a  diffuses in the plasma generation chamber  11  below the electrode  30 . A gas supply  50   a  is connected to the gas supply pipe  54   a . The gas supply  50   a  includes gas supply sources  51   a  to  51   b , mass flow controllers (MFCs)  52   a  to  52   b , and valves  53   a  to  53   b . The gas supply  50   a  is an example of a gas supply part. 
     The gas supply source  51   a , which is a supply source of a purge gas, is connected to the valve  53   a  via the MFC  52   a . In the present embodiment, the purge gas is, for example, an inert gas such as He gas, Ar gas, or N 2  gas. The MFC  52   a  controls the flow rate of the purge gas supplied from the gas supply source  51   a , and supplies the purge gas, of which the flow rate is controlled, into the plasma generation chamber  11  through the valve  53   a  and the gas supply pipe  54   a.    
     The gas supply source  51   b , which is a supply source of a reaction gas, is connected to the valve  53   b  via the MFC  52   b . In the present embodiment, the reaction gas is, for example, O 2  gas, H 2 O gas, NH 3  gas, N 2  gas. H 2  gas, or the like. The MFC  52   b  controls the flow rate of the reaction gas supplied from the gas supply source  51   b , and supplies the reaction gas, of which the flow rate is controlled, into the plasma generation chamber  11  through the valve  53   b  and the gas supply pipe  54   a . The gas is supplied into the plasma generation chamber  11  in the form of a shower. 
     A high-frequency power supply  32  is electrically connected to the upper electrode  30  via a matcher  31 . The high-frequency power supply  32  supplies a first high-frequency power for generating plasma, for example, a first high-frequency power having a frequency of 300 kHz to 2.45 GHz to the electrode  30  via the matcher  31 . The high-frequency power supply  32  is an example of a first power supply. The matcher  31  matches the internal impedance of the high-frequency power supply  32  with a load impedance. The first high-frequency power supplied to the electrode  30  is radiated from the lower surface of the electrode  30  into the plasma generation chamber  11 . The reaction gas supplied into the plasma generation chamber  11  is converted into plasma by the first high-frequency power radiated into the plasma generation chamber  11 . 
     Between the electrode  30  and the stage  13 , there is provided a separation unit  20  configured to separate the space within the processing container  10  into a plasma generation chamber  11  and a processing chamber  12 . The separation unit  20  has a separation plate (e.g. an electrode plate  200 ), an insulating plate  210 , a temperature controller (e.g. a cooling plate  220 ), and a gas supply plate  230 . 
     The electrode plate  200  is formed of, for example, a metal such as aluminum having an anodized surface. The electrode plate  200  is provided with a plurality of through holes  201  penetrating the electrode plate  200  in the thickness direction. The electrode plate  200  is supported by the insulating member  16  and the insulating plate  210  so as to be parallel to the electrode  30 . The electrode plate  200  is an example of a separation plate. 
     A high-frequency power supply  203  is electrically connected to the upper electrode plate  200  via a matcher  202 . The high-frequency power supply  203  is a second high-frequency power for controlling the distribution of plasma in the plasma generation chamber  11 , the density of plasma in the plasma generation chamber  11 , the amount of active species passing through the through holes  201  in the electrode plate  200 , and the like. The high-frequency power supply  203  supplies the second high-frequency power having a frequency different from that of the first high-frequency power to the electrode plate  200  via the matcher  202 . The frequency of the second high-frequency power is, for example, 300 kHz to 300 MHz. The high-frequency power supply  203  is an example of a second power supply. The matcher  202  matches the internal impedance of the high-frequency power supply  203  with a load impedance. 
     The insulating plate  210  is formed of, for example, an insulator such as ceramics or quartz, and is provided between the electrode plate  200  and the cooling plate  220 . The insulating plate  210  is provided with a plurality of through holes  211  which penetrates the insulating plate  210  in the thickness direction. The electrode plate  200  and the cooling plate  220  are electrically insulated by the insulating plate  210 . 
     The cooling plate  220  is formed of a metal such as aluminum having an anodized surface. The cooling plate  220  is provided with a plurality of through holes  221  that penetrates the cooling plate  220  in the thickness direction. The cooling plate  220  is supported by the side wall of the processing container  10  so as to be parallel to the electrode  30 . The cooling plate  220  is in contact with the surface of the electrode plate  200  near the processing chamber  12  via the insulating plate  210 . The cooling plate  220  is grounded via the side wall of the processing container  10 . 
     The gas supply plate  230  is formed of a metal such as aluminum having an anodized surface. The gas supply plate  230  is provided with a plurality of through holes  231  that penetrates the gas supply plate  230  in the thickness direction. The gas supply plate  230  is disposed in the processing chamber  12 , and is supported by the side wall of the processing container  10 . The gas supply plate  230  is grounded via the side wall of the processing container  10 . 
     A flow path  232  is formed in the gas supply plate  230 , and gas ejection ports  233  are provided in the flow path  232 . A gas supply  50   b  is connected to the flow path  232 . The gas supply  50   b  includes a gas supply source  51   c , an MFC  52   c , and a valve  53   c . A gas supply source  51   c , which is a supply source of a precursor gas, is connected to the valve  53   c  via the MFC  52   c.    
     In the present embodiment, the precursor gas is, for example, bis(diethylamino)silane (H 2 Si[N(C 2 H 5 ) 2 ] 2 ) gas, dichlorosilane (SiH 2 Cl 2 ) gas, or the like. The MFC  52   c  controls the flow rate of the precursor gas supplied from the gas supply source  51   c , and supplies the precursor gas, of which the flow rate is controlled, into the flow path  232  in the gas supply plate  230  through the valve  53   c . The precursor gas supplied into the flow path  232  diffuses in the flow path  232  and is supplied from the gas ejection ports  233  into the processing chamber  12  in a shower shape. The space in the plasma generation chamber  11  and the space in the processing chamber  12  are connected to each other through the through holes in the separation unit  20 , that is, the through holes  201  in the electrode plate  200 , the through holes  211  in the insulating plate  210 , the through holes  221  in the cooling plate  220 , and the through holes  231  in the gas supply plate  230 . 
     Descriptions will be continued with reference to  FIGS. 2 to 4 .  FIG. 2  is a plan view illustrating an exemplary cooling plate  220  in a first embodiment of the present disclosure, and  FIG. 3  is a cross-sectional view illustrating the exemplary cooling plate  220  in the first embodiment of the present disclosure, taken along line A-A.  FIG. 4  is a cross-sectional view illustrating the exemplary cooling plate  220  in the first embodiment of the present disclosure, taken along line B-B. The A-A cross section of the cooling plate  220  exemplified in  FIG. 2  corresponds to  FIG. 3 , and the B-B cross section of the cooling plate  220  exemplified in  FIG. 3  corresponds to  FIG. 4 . The number of through holes  221  provided in the cooling plate  220  exemplified in  FIGS. 1 to 4  is smaller than the actual number for convenience of description. 
     In the cooling plate  220 , a flow path  222  through which a temperature-controlled fluid circulates is formed. The fluid flowing in the flow path  222  is supplied from a temperature control device such as a chiller (not illustrated) through a pipe  223   a . Then, for example, the fluid flowing in the flow path  222  as indicated by the arrows in  FIG. 4  is returned to the temperature control device through the pipe  223   b . The fluid flowing in the flow path  222  is, for example, a liquid such as Galden (registered trademark). The fluid flowing in the flow path  222  may be another liquid such as water, or a gas. 
     The electrode plate  200  is heated by the plasma generated in the plasma generation chamber  11 , and the heat of the electrode plate  200  is transferred to the cooling plate  220  via the insulating plate  210 . The heat of the cooling plate  220  is transferred to the fluid by heat exchange with the fluid flowing in the flow path  222 . By controlling the temperature of the fluid flowing in the flow path  222 , it is possible to cool the electrode plate  200 , the insulating plate  210 , and the cooling plate  220 . This suppresses the temperature rise of the separation unit  20 , and thus suppresses deformation and breakage of the separation unit  20 . The cooling plate  220  is an example of a temperature controller. 
     Returning to  FIG. 1 , descriptions will be continued. The control device  3  has a memory, a processor, and an input/output interface. The processor controls the respective parts of the apparatus body  2  via an input/output interface by reading and executing a program or a recipe stored in the memory. In the present embodiment, the control device  3  controls each part of the apparatus body  2  such that a silicon oxide film or the like is formed on the wafer W placed on the stage  13  through, for example, plasma-enhanced ALD (PEALD) method. 
     For example, the gate valve G is opened, and a wafer W is carried into the processing container  10  by a transport mechanism, such as a robot arm (not shown), and is placed on the stage  13 . Then, after the gate valve G is closed, the control device  3  drives the exhaust device  42  and adjusts the opening degree of the pressure adjustment valve  41  so as to adjust the pressure in the processing container  10 . Then, the control device  3  executes a plurality of ALD cycles including an adsorption step, a first purge step, a reaction step, and a second purge step, thereby forming a predetermined film on the wafer W placed on the stage  13 . 
     In the adsorption step, the valve  53   c  is opened, and the precursor gas, of which the flow rate is controlled by the MFC  52   c , is supplied into the flow path  232  in the gas supply plate  230  through the gas supply pipe  54   b . The precursor gas supplied into the flow path  232  diffuses in the flow path  232  and is supplied from the gas ejection ports  233  into the plasma generation chamber  11  in a shower shape. The molecules of the precursor gas supplied into the processing chamber  12  are adsorbed on the surface of the wafer W on the stage  13 . Then, the valve  53   c  is closed. 
     In the first purge step, the valve  53   a  is opened, and the purge gas, of which the flow rate is controlled by the MFC  52   a , is supplied into the plasma generation chamber  11  through the gas supply pipe  54   a . The purge gas supplied into the plasma generation chamber  11  diffuses in the plasma generation chamber  11 , and is supplied into the processing chamber  12  through the through holes in the separation unit  20  in a shower shape. The purge gas supplied into the processing chamber  12  purges the molecules of the precursor excessively adsorbed on the surface of the wafer W. Then, the valve  53   a  is closed. 
     In the reaction step, the valve  53   b  is opened, and the reaction gas, of which the flow rate is controlled by the MFC  52   b , is supplied into the plasma generation chamber  11  through the gas supply pipe  54   a . The reaction gas supplied into the plasma generation chamber  11  diffuses in the plasma generation chamber  11 . Then, the first high-frequency power from the high-frequency power supply  32  is supplied into the plasma generation chamber  11  via the matcher  31  and the electrode  30 , and the reaction gas in the plasma generation chamber  11  is converted into plasma. In addition, the second high-frequency power from the high-frequency power supply  203  is supplied into the plasma generation chamber  11  via the matcher  202  and the electrode plate  200 , and the distribution of the plasma in the plasma generation chamber  11  is controlled. 
     The active species contained in the plasma are supplied into the processing chamber  12  through the through holes in the separation unit  20 . The active species supplied into the processing chamber  12  react with the molecules of the precursor gas adsorbed on the wafer W. and forms a predetermined film so as to be laminated on the wafer W. Then, the valve  53   b  is closed. The ions contained in the plasma are absorbed by the electrode plate  200 , the cooling plate  220 , or the gas supply plate  230 , and are hardly supplied to the processing chamber  12 . This reduces ion damage to the wafer W. 
     In the second purge step, the valve  53   a  is opened, and the purge gas, of which the flow rate is controlled by the MFC  52   a , is supplied into the plasma generation chamber  11  through the gas supply pipe  54   a . The purge gas supplied into the plasma generation chamber  11  diffuses in the plasma generation chamber  11 , and is supplied into the processing chamber  12  through the through holes in the separation unit  20  in a shower shape. The purge gas supplied into the processing chamber  12  purges reaction by-products and the like formed on the surface of the wafer W. Then, the valve  53   a  is closed. 
     The first embodiment has been described. As described above, the plasma processing apparatus  1  of the present embodiment includes a gas supply  50   a , a high-frequency power supply  32 , an electrode plate  200 , and a cooling plate  220 . The gas supply  50   a  supplies gas into the plasma generation chamber  11 . The high-frequency power supply  32  converts the gas supplied into the plasma generation chamber  11  into plasma by supplying the first high-frequency power into the plasma generation chamber  11 . The electrode plate  200  is a plate-shaped electrode plate  20 X), which separates the plasma generation chamber  11  from the processing chamber  12  below the plasma generation chamber  11 , and has a plurality of through holes  201  for guiding active species, contained in the plasma generated in the plasma generation chamber  11 , to the processing chamber  12 . The cooling plate  220  has the flow path  222  through which a fluid, of which the temperature is controlled, flows, and controls the temperature of the electrode plate  200  by heat exchange with the fluid. Thus, it is possible to suppress the temperature rise of the separation plate. 
     In the above-described embodiment, the electrode plate  200  is formed of a metal. In addition, the plasma processing apparatus  1  further includes a high-frequency power supply  203  configured to supply the second high-frequency power having a frequency different from that of the first high-frequency power to the electrode plate  200 . The cooling plate  220  is in contact with the surface of the separation plate near the processing chamber  12  via the insulating plate  210 . Thus, it is possible to suppress the temperature rise of the separation plate while insulating the electrode plate  200  and the cooling plate  220 . 
     Second Embodiment 
     In the first embodiment, the inside of the flow path  222  of the cooling plate  220  is a cavity. In contrast, the cooling plate  220  of the present embodiment differs from that in the first embodiment in that the flow path  222  is filled with a porous metal. The other parts of the plasma processing apparatus  1  other than the cooling plate  220  are the same as those of the plasma processing apparatus  1  according to the first embodiment, and detailed descriptions thereof will be omitted. 
       FIG. 5  is a cross-sectional view illustrating an exemplary cooling plate  220  in the second embodiment of the present disclosure.  FIG. 6  is a cross-sectional view illustrating the exemplary cooling plate  220  in the second embodiment of the present disclosure, taken along line B-B in  FIG. 5 . The plan view of the cooling plate  220  in the present embodiment is the same as that in  FIG. 2 . A-A cross section of the cooling plate  220  of the present embodiment, which is identical to that in  FIG. 2 , corresponds to  FIG. 5 , and the B-B cross section of the cooling plate  220  exemplified in  FIG. 5  corresponds to  FIG. 6 . 
     For example, as illustrated in  FIGS. 5 and 6 , a porous metal  224  having a large number of cavities  225  is arranged in the flow path  222 . Each cavity  225  has an elongated shape extending in the direction from the pipe  223   a  to the pipe  223   b . Each cavity  225  is connected to one or more other cavities  225 . For that reason, the fluid that has flowed into the flow path  222  through the pipe  223   a  flows through the cavities  225  in the porous metal  224 , and is returned to the temperature control device, such as a chiller, through the pipe  223   b . When the fluid flows in the cavities  225 , heat is exchanged between the fluid and the porous metal  224 , and the heat of the porous metal  224  is transferred to the cooling plate  220 . Thus, heat exchange between the fluid and the cooling plate  220  can be performed more efficiently. 
     The second embodiment has been described. As described above, in the plasma processing apparatus  1  of the present embodiment, the porous metal  224  is arranged in the flow path  222  in the cooling plate  220 . Thus, heat exchange between the fluid and the cooling plate  220  can be performed more efficiently. 
     Third Embodiment 
     In the first embodiment, since the flow of the fluid in the flow path  222  in the cooling plate  220  is delayed in a region far from the pipe  223   a  and the pipe  223   b , the heat dissipation efficiency by the fluid may be reduced. In contrast, the present embodiment differs from the first embodiment in that a guide wall is provided in the flow path  222  in the cooling plate  220  such that the fluid flows through the entire flow path  222 . The other parts of the plasma processing apparatus  1  other than the cooling plate  220  are the same as those of the plasma processing apparatus  1  according to the first embodiment, and detailed descriptions thereof will be omitted. 
       FIG. 7  is a cross-sectional view illustrating an exemplary cooling plate  220  in a third embodiment of the present disclosure. For example, as illustrated in  FIG. 7 , a guide wall  226  is provided in the flow path  222 . The guide wall  226  regulates the flow path of the fluid flowing in the flow path  222  so as to flow through the entire flow path  222 . This allows the fluid to flow through the entire flow path  222 , for example, as indicated by the arrows in  FIG. 7 . This makes it possible to suppress a decrease in the heat dissipation efficiency by the fluid, and thus efficiently cool the separation unit  20 . 
     Fourth Embodiment 
     In the third embodiment, by providing the guide wall  226  in the flow path  222 , the fluid flows in a direction intersecting the direction from the pipe  223   a  to the pipe  223   b . In contrast, the present embodiment differs from the third embodiment in that a plurality of flow passages is formed in the flow path  222  in the direction from the pipe  223   a  to the pipe  223   b . The other parts of the plasma processing apparatus  1  other than the cooling plate  220  are the same as those of the plasma processing apparatus  1  according to the third embodiment, and detailed descriptions thereof will be omitted. 
       FIG. 8  is a plan view illustrating an exemplary cooling plate  220  in a fourth embodiment of the present disclosure.  FIG. 9  is a cross-sectional view illustrating the exemplary cooling plate  220  in the fourth embodiment of the present disclosure, taken along line A 1 -A 1 .  FIG. 10  is a cross-sectional view illustrating the exemplary cooling plate  220  in the fourth embodiment of the present disclosure, taken along line A 2 -A 2 .  FIG. 11  is a cross-sectional view illustrating the exemplar) cooling plate  220  in the fourth embodiment of the present disclosure, taken along line B-B. The A 1 -A 1  cross section of the cooling plate  220  exemplified in  FIG. 8  corresponds to  FIG. 9 , the A 2 -A 2  cross section of the cooling plate  220  exemplified in  FIG. 8  corresponds to  FIG. 10 , and the B-B cross section of the cooling plate  220  exemplified in  FIGS. 9 and 10  corresponds to  FIG. 11 . 
     For example, as illustrated in  FIG. 11 , a plurality of flow paths  222  are formed in the cooling plate  220  in a direction from the pipe  223   a  to the pipe  223   b . The fluid supplied from the pipe  223   a  flows into each flow path  222  through a branch portion  227   a . Then, the fluid that has flowed through each flow path  222  flows to the pipe  223   b  through a collecting portion  227   b , and is returned to a temperature control device such as a chiller. Each flow path  222  in the present embodiment is formed in a direction from the pipe  223   a  to the pipe  223   b . For that reason, it is possible to reduce the pressure loss of the fluid when flowing in the flow path  222 , and thus reduce the load on the pump of the temperature control device such as a chiller. 
     Fifth Embodiment 
     In the fourth embodiment, each flow path  222  in the cooling plate  220  is a cavity. In contrast, the cooling plate  220  of the present embodiment differs from that in the fourth embodiment in that the flow path  222  is filled with a porous metal. The other parts of the plasma processing apparatus  1  other than the cooling plate  220  are the same as those of the plasma processing apparatus  1  according to the fourth embodiment, and detailed descriptions thereof will be omitted. 
       FIG. 12  is a cross-sectional view illustrating an exemplary cooling plate  220  in a fifth embodiment of the present disclosure. For example, as illustrated in  FIG. 12 , a porous metal  224  having a large number of cavities  225  are arranged in each flow path  222 . Each cavity  225  has an elongated shape extending in the direction from the pipe  223   a  to the pipe  223   b . Each cavity  225  is connected to one or more other cavities  225 . For that reason, the fluid supplied through the pipe  223   a  flows through the cavities  225  in the porous metal  224  disposed in each of the flow paths  222  via a branch portion  227   a , and is returned to a temperature control device such as a chiller through the collecting portion  227   b  and the pipe  223   b . By arranging the porous metal  224  in each of the flow paths  222 , heat exchange between the fluid and the cooling plate  220  can be performed more efficiently. 
     Sixth Embodiment 
     The separation unit  20  in the first embodiment includes an electrode plate  200 , an insulating plate  210 , a cooling plate  220 , and a gas supply plate  230 . In contrast, the separation unit  20  of the present embodiment differs from that in the first embodiment in that it includes the cooling plate  220  but does not include the electrode plate  200 , the insulating plate  210 , and the gas supply plate  230 . The following description focuses on the differences from the first embodiment. 
       FIG. 13  is a schematic cross-sectional view illustrating an exemplary plasma processing apparatus  1  in a sixth embodiment of the present disclosure. In the present embodiment, the separation unit  20  has a cooling plate  220 . The cooling plate  220  is grounded via the processing container  10  and functions as a lower electrode with respect to the electrode  30 . The space in the plasma generation chamber  11  and the space in the processing chamber  12  are connected via through holes  221  in the cooling plate  220 . 
     A gas supply  50  is connected to the electrode  30  via a gas supply pipe  54 . The gas supply  50  includes gas supply sources  51   a  to  51   c , MFCs  52   a  to  52   c , and valves  53   a  to  53   c . The flow rate of a precursor gas supplied from the gas supply source  51   c  is controlled by the MFC  52   c , and is supplied into the plasma generation chamber  11  through the valve  53   c  and the gas supply pipe  54 . The precursor gas supplied into the plasma generation chamber  11  diffuses in the plasma generation chamber  11  and is supplied to the processing chamber  12  through the through holes  221  in the cooling plate  220  in a shower shape. 
     Ions contained in the plasma generated in the plasma generation chamber  11  are absorbed by the cooling plate  220  and are hardly supplied to the processing chamber  12 . For that reason, the present embodiment also reduces ion damage to a wafer W. 
     In the present embodiment, the cooling plate  220  has both the function of a separation plate for separating the plasma generation chamber  11  and the processing chamber  12  and the function of a temperature controller for controlling the temperature of the separation plate through heat exchange with a fluid since the cooling plate  220  has therein a flow path through which the fluid flows in a temperature-controlled manner. That is, in the present embodiment, the temperature controller and the separation plate are integrally configured as the cooling plate  220 . 
     Seventh Embodiment 
     The cooling plate  220  in the sixth embodiment is grounded via the processing container  10 . In contrast, the present embodiment differs from the sixth embodiment in that high-frequency power is supplied to the cooling plate  220 . The following description focuses on the differences from the sixth embodiment. 
       FIG. 14  is a schematic cross-sectional view illustrating an exemplary plasma processing apparatus  1  in a seventh embodiment of the present disclosure. In the present embodiment, the separation unit  20  has a cooling plate  220 . The space in the plasma generation chamber  11  and the space in the processing chamber  12  are connected via through holes  221  in the cooling plate  220 . The cooling plate  220  is supported by the processing container  10  via an insulating member  16   a . A high-frequency power supply  203  is electrically connected to the cooling plate  220  via a matcher  202 . The high-frequency power supply  203  supplies the second high-frequency power to the cooling plate  220  via the matcher  202 . This makes it possible to control the distribution of plasma in the plasma generation chamber  11 , the density of plasma in the plasma generation chamber  11 , the amount of active species passing through the through holes  221  in the cooling plate  220 , and the like, while reducing ion damage to the wafer W. 
     In the first embodiment, the cooling plate  220  may also be supported by the processing container  10  via the insulating member  16   a , and the high-frequency power supply  203  may be connected to the cooling plate  220  via the matcher  202 . In this case, the electrode plate  200  is not provided. The insulating plate  210  is disposed preferably between the cooling plate  220  and the gas supply plate  230 . 
     [Others] 
     The technology disclosed herein is not limited to the embodiments described above, and various modifications are possible within the scope of the gist of the present disclosure. 
     For example, in the first to fifth embodiments described above, the insulating plate  210  is interposed between the electrode plate  200  and the cooling plate  220 , but the disclosed technology is not limited thereto. Alternatively, the electrode plate  200  and the cooling plate  220  may be in direct contact, and the insulating plate  210  may be interposed between the cooling plate  220  and the gas supply plate  230 . In this case, the lower surface of the electrode plate  200  and the upper surface of the cooling plate  220  are preferably joined through welding or the like. This makes it possible to perform heat exchange between the electrode plate  200  and the cooling plate  220  more efficiently. 
     In addition, in each of the above embodiments, the plasma processing apparatus  1  for forming a predetermined film on a wafer W through PEALD method has been described as an example, but the technology disclosed herein is not limited thereto. The technology disclosed herein is applicable to an apparatus that performs film formation by plasma chemical vapor deposition (CVD) method as long as the apparatus performs film formation using plasma. In addition, the technology disclosed herein is applicable to an etching apparatus, a cleaning apparatus, and the like as long as the apparatus performs processing using plasma. 
     In each of the embodiments described above, capacitively coupled plasma (CCP) is used as an example of a plasma source, but the technology disclosed herein is not limited thereto. As the plasma source, for example, inductively coupled plasma (ICP), microwave-excited surface wave plasma (SWP), electron cyclotron resonance plasma (ECP), or helicon wave-excited plasma (HWP) may be used. 
     According to various aspects and embodiments of the present disclosure, it is possible to suppress temperature rise of the separation plate. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosures. Indeed, the embodiments described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosures. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosures.