Abstract:
Provided is a method of manufacturing a support unit that supports a substrate. The method includes: providing a support plate formed of a non-conductive material and supporting a substrate; providing a base plate disposed below the support plate and formed of a material including a conductive material; and depositing a metallic layer at a bottom of the support plate and coupling the metallic layer and the base plate through brazing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This U.S. non-provisional patent application claims priority under 35 U.S.C. §119 of Korean Patent Application Nos. 10-2013-0131350, filed on Oct. 31, 2013, and 10-2014-0009050, filed on Jan. 24, 2014, the entire contents of which are hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention disclosed herein relates to a substrate treating device, and more particularly, to a substrate treating device using plasma. 
         [0003]    In order to manufacture a semiconductor device, various processes such as photolithography, etching, ashing, ion implantation, thin film deposition, and cleaning are performed on a substrate to form a desired pattern thereon. Among processes, an etching process is a process for removing a selected area from a layer formed on a substrate through wet etching or dry etching. 
         [0004]    For the dry etching, an etching device using plasma is used. In general, in order to form plasma, an electromagnetic field is formed in an inner space of a chamber and excites a process gas provided to the chamber to a plasma state. 
         [0005]    The plasma refers to an ionized gas state formed of ions or electrons and radicals. The plasma is generated by very high temperatures, strong electric fields, or RF electromagnetic fields. A semiconductor device manufacturing process performs an etching process by using plasma. An etching process is performed as ion particles contained in plasma collide with a substrate. 
         [0006]    Typically, an electrostatic chuck includes a support plate and a metallic body. The support plate and the body adhere to each other by an organic bonder such as silicon or acrylic. However, silicon has excellent heat resistance but low thermal resistance. Accordingly, silicon is not damaged by a heat occurring during a substrate treating process but does not effectively block heat transfer between the body and the support plate. Acrylic has excellent thermal resistance but low heat resistance. Acrylic prevents heat loss between the support plate and the body but is damaged by heat occurring during a substrate treating process. 
         [0007]    In such a way, in relation to a currently used organic bonder, the life span is reduced and the process temperature rise is limited due to the non-uniform temperature occurrence in an electrostatic chuck resulting from thermal durability deterioration. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides a method of manufacturing a support unit having excellent thermal durability in an electrostatic chuck used during a substrate treating process and a substrate treating device including the support unit. 
         [0009]    Embodiments of the present invention provide methods of manufacturing a support unit that supports a substrate. The methods include: providing a support plate formed of a non-conductive material and supporting a substrate; providing a base plate disposed below the support plate and formed of a material including a conductive material; and depositing a metallic layer at a bottom of the support plate and coupling the metallic layer and the base plate through brazing. 
         [0010]    In some embodiments, the methods may further include providing a filler of a metallic material between the support plate and the base plate to couple the support plate and the base plate by using the filler as a medium. 
         [0011]    In other embodiments, the base plate may be formed of a conductive composite material obtained by mixing the conductive material and an added material to minimize a heat stress due to a thermal expansion rate difference between the base plate and the support plate. 
         [0012]    In still other embodiments, the conductive material may include Ti or Al and the added material may include one of SiC, Al 2 O 3 , Si, graphite, and glass fiber. 
         [0013]    In even other embodiments, the added material may have a thermal expansion rate less than a thermal expansion rate difference between the conductive material and a material of the support plate. 
         [0014]    In yet other embodiments, the conductive composite material may include the added material of 10% to 70%. 
         [0015]    In further embodiments, the metallic layer may be deposited to the bottom of the support plate through vacuum deposition or plating. 
         [0016]    In still further embodiments, an uneven part may be provided to minimize a stress due to a thermal expansion of a bottom of the metallic layer or a top surface form of the base plate. 
         [0017]    In even further embodiments, the metallic layer may include one of Ti, Ni, and Ag. 
         [0018]    In yet further embodiments, the filler may include Al. 
         [0019]    In yet further embodiments, a metallic mesh buffering a thermal expansion at high temperature may be provided in the filler. 
         [0020]    In yet further embodiments, the metallic mesh may have a porosity of 20% to 80%. 
         [0021]    In other embodiments of the present invention, substrate support units include: a support plate including an electrode that adsorbs a substrate by electrostatic force and having a bottom where a metallic layer is deposited; and a base plate disposed below the support plate, connected to a high frequency power, and coupled to the metallic layer through brazing. 
         [0022]    In some embodiments, an even part may be provided to minimize a stress due to a thermal expansion of a bottom of the metallic layer, a top surface of the base plate, or a form of a metallic deposition layer and the uneven part may be provided in a mesh form or an embossing form. 
         [0023]    In other embodiments, the base plate may include a conductive composite material obtained by adding one of SiC, Al 2 O 3 , Si, graphite, and glass fiber to a conductive material to minimize a heat stress due to a thermal expansion rate difference between the base plate and the support plate. 
         [0024]    In still other embodiments, the substrate support units may further include a bonding part disposed between the metallic layer and the base plate and fixing the metallic layer and the base plate by using a filler as a medium. 
         [0025]    In even other embodiments, the bonding part may further include a metallic mesh therein. 
         [0026]    In still other embodiments of the present invention, substrate treating devices include: a chamber having a treating space therein; a support unit disposed in the chamber and supporting a substrate; a gas supply unit supplying a process gas to the treating space; and a plasma source generating plasma from the process gas, wherein the support unit includes: a support plate including an electrode that adsorbs a substrate by electrostatic force and having a bottom where a metallic layer is deposited; and a base plate provided below the support plate and connected to a high frequency power; and a metallic filler disposed between the support plate and the base plate and bonding the support plate and the base plate by brazing. 
         [0027]    In some embodiments, the base plate may include a conductive composite material obtained by adding one of Sic, Al 2 O 3 , Si, graphite, and glass fiber to a conductive material to minimize a heat stress due to a thermal expansion rate difference between the base plate and the support plate. 
         [0028]    In other embodiments, the filler may further include a metallic mesh therein. 
         [0029]    In still other embodiments, the filler may be provided in a metallic mesh form. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    The accompanying drawings are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present invention and, together with the description, serve to explain principles of the present invention. In the drawings: 
           [0031]      FIG. 1  is a sectional view illustrating a substrate treating device according to an embodiment of the present invention; 
           [0032]      FIG. 2  is a plan view illustrating a support plate of a support unit of  FIG. 1  according to an embodiment of the present invention; 
           [0033]      FIG. 3  is a sectional view illustrating a support plate of a support unit, taken along a line X-X′ of  FIG. 2 ; 
           [0034]      FIG. 4  is a schematic separation diagram illustrating components of a support unit of  FIG. 1 ; 
           [0035]      FIG. 5  is a flowchart illustrating a method of manufacturing a support unit; 
           [0036]      FIG. 6  is a view illustrating a modified embodiment of an electrostatic chuck; 
           [0037]      FIG. 7  is a view illustrating another modified embodiment of an electrostatic chuck; and 
           [0038]      FIG. 8  is a view illustrating another modified embodiment of an electrostatic chuck. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0039]    Preferred embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be constructed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. 
         [0040]      FIG. 1  is a sectional view illustrating a substrate treating device according to an embodiment of the present invention. 
         [0041]    Referring to  FIG. 1 , the substrate treating device  10  treats a substrate W by using plasma. For example, the substrate treating device  10  may perform a process such as etching, cleaning, and ashing on the substrate W by using plasma. The substrate treating device  10  includes a chamber  100 , a support unit  200 , a plasma source  300 , a gas supply unit  400 , and a baffle unit  500 . 
         [0042]    The chamber  100  provides a treatment space therein where a substrate treating process is performed. The chamber  100  has a treatment space in a closed shape therein. The chamber  100  is provided with a metallic material. The chamber  100  may be provided with an aluminum material. The chamber  100  may be grounded. A discharge hole  102  is formed in the bottom surface of the chamber  100 . The discharge hole  102  is connected to a discharge line  151 . Reaction by-products occurring during a manufacturing process and gas staying in an inner space of a chamber may be discharged to the outside through the discharge line  151 . The inside of the chamber  100  is reduced to a predetermined pressure by a discharge process. 
         [0043]    According to an embodiment of the present invention, a liner  130  may be provided to the inside of the chamber  100 . The liner  130  has a cylindrical form with the top and bottom surfaces open. The chamber  100  may be provided to contact the inner surface of the chamber  100 . The liner  130  protects the inner wall of the chamber  100  as so to prevent it from being damaged by arc discharge. Additionally, the liner  130  also prevents impurities occurring during a substrate treating process from being deposited on the inner wall of the chamber  100 . Selectively, the liner  130  may not be provided. 
         [0044]    The support unit  200  is disposed inside the chamber  100 . The support unit  200  supports the substrate W. The support unit  200  may include an electrostatic chuck  210  adsorbing the substrate W by using an electrostatic force. Unlike this, the support unit  200  may support the substrate W through various methods such as mechanical clamping. Hereinafter, the support unit  200  including the electrostatic chuck  210  will be described. 
         [0045]    The support unit  200  includes the electrostatic chuck  210 , a lower cover  250 , and a plate  270 . The support unit  200  may be disposed spaced from the bottom surface of the chamber  100  to the top in the chamber  100 . 
         [0046]    The electrostatic chuck  210  includes a support plate  220  and a base plate  230 . 
         [0047]    The support plate  220  is provided to the top end part of the electrostatic chuck  210 . 
         [0048]    The support plate  220  is formed of a non-conductive material. A metallic layer  226  is deposited at the bottom surface of the support plate  220 . Unlike this, the support plate  220  may be provided with a mixed material of a conductive material included in the material of the base plate  230  and an added material. According to an embodiment of the present invention, the support plate  220  may include a disc-shaped dielectric substance. The substrate W is disposed at the top surface of the support plate  220 . The top surface of the support plate  220  has a smaller radius than the substrate W. Due to this, the edge heating area of the substrate W is disposed at the outer side of the support plate  220 . A first supply passage  221  shown in  FIG. 2  is formed at the top surface of the support plate  220 . A plurality of first supply passages  221  are formed spaced from each other and are provided as a path through which a heat transfer medium is supplied to the bottom surface of the substrate W. 
         [0049]      FIG. 2  is a plan view of a support plate according to an embodiment of the present invention.  FIG. 3  is a sectional view illustrating a support plate of a support unit, taken along a line X-X′ of  FIG. 2 . 
         [0050]    Referring to  FIGS. 2 and 3 , the support plate  220  includes an inner groove  221 , an external groove  222 , a protrusion  224 , a projection part  226 , and a second supply passage  233 . The inner groove  221  may be disposed at the top center part of the support plate  220 . As seen from the top, the inner groove  221  may be provided in a circular form. The inner groove  221  may be provided to have a first depth dl. 
         [0051]    Additionally, the inner groove  221  may be provided to have a first area A1, as seen from the top. The inner groove  221  may be provided with a first volume V1. At this point, the first volume V1 means a volume where a heat transfer gas is disposed in the inner groove  221 . Accordingly, the first volume V1 means a volume obtained by excluding the volume of the protrusion part  226  in the inner groove  221  from the volume of the inner groove  221 . 
         [0052]    As seen from the top, the outer groove  222  may be provided in an annular ring form. The outer groove  222  may be provided in a form surrounding the inner groove  221 . The outer groove  222  may be provided to have a second depth d2. At this point, the second depth d2 of the outer groove  222  may be different from the first depth d1 of the inner groove  221 . Unlike this, the second depth d2 of the outer groove  222  may be identical to the first depth d1 of the inner groove  221 . 
         [0053]    As seen from the top, the outer groove  222  may be provided to have a second area A2. The second area A2 of the external groove  222  may be broader than the first area A1 of the inner groove  221 . Unlike this, the second area A2 of the external groove  222  may be identical to the first area A1 of the inner groove  221 . The outer groove  222  may be provided with a second volume V2. At this point, the second volume V2 means a volume where a heat transfer gas is disposed in the outer groove  222 . Accordingly, the second volume V2 means a volume obtained by excluding the volume of the protrusion part  226  in the outer groove  222  from the volume of the outer groove  222 . According to an embodiment of the present invention, the second volume V2 of the external groove  222  may be greater than the first volume V1 of the inner groove  221 . Unlike this, the second volume V2 of the external groove  222  may be identical to the first volume V1 of the inner groove  221 . 
         [0054]    The protrusion  224  may be provided between the inner groove  221  and the outer groove  222 . The protrusion  224  may be provided as a boundary for distinguishing the inner groove  221  from the outer groove  222 . The top end height of the protrusion  224  may be identical to the top end height of the protrusion part  226 . 
         [0055]    The protrusion part  226  is provided in the inner groove  221  and the outer groove  222 . The protrusion part  226  may be provided in plurality. The protrusion part  226  may include a first protrusion part  226   a  and a second protrusion part  226   b . The first protrusion part  226   a  may be disposed in the inner groove  221 . The first protrusion part  226   a  may be provided in plurality. The plurality of first protrusion parts  226   a  may be disposed at regular intervals. The first protrusion part  226   a  may have a depth identical to the first depth d1 of the inner groove  221 . The top end height of the first protrusion part  226   a  may be identical to the top end height of the protrusion  224 . 
         [0056]    The second protrusion part  226   b  may be disposed in the outer groove  222 . The second protrusion part  226   b  may be provided in plurality. The plurality of second protrusion parts  226   b  may be disposed at regular intervals. The second protrusion part  226   b  may have a depth identical to the second depth d2 of the outer groove  222 . The top end height of the second protrusion part  226   b  may be identical to the top end height of the protrusion  224 . 
         [0057]    The second supply passage  233  supplies a heat transfer gas to the bottom of the substrate W. The second supply passage  233  may supply a heat transfer gas to each of the inner groove  221  and the outer groove  222 . The second supply passage  233  may be connected to each of the inner groove  221  and the outer groove  222 . For example, the second supply passage  233  may include an inner second supply passage  233   a  and an outer second supply passage  233   b . The inner second supply passage  233   a  is connected to the inner groove  221  to deliver a heat transfer gas to the inner groove  221 . The outer second supply passage  233   b  is connected to the outer groove  222  to deliver a heat transfer gas to the outer groove  222 . 
         [0058]    The heat transfer gas serves as a heat transfer medium between the substrate W and the support unit  200 . The heat transfer gas provides a fluid having great thermal conductivity so that heat is transferred easily between the substrate W and the support unit  200 . Accordingly, the temperature of the substrate W may be adjusted by adjusting the amount of a heat transfer gas provided at the top surface of the support unit  200 . As mentioned above, a plurality of grooves having different depths, widths, and volumes are provided at the top surface of the support unit  200 , so that the amount of a heat transfer gas disposed between the substrate W and the support unit  200  may be adjusted. Thus, the temperature may be easily adjusted according to an area of the substrate W. For example, the heat transfer gas may include helium (He). 
         [0059]    Referring to  FIG. 1  again, the support plate  220  further includes a first electrode  223  and a heater  225 , embedded in the support plate  220 . 
         [0060]    The first electrode  223  is electrically connected to a first power  223   a . The power  223   a  includes DC power. A switch  223   b  is installed between the first electrode  223  and the first power  223   a . The first electrode  223  may be electrically connected to a first power  223   a  by ON/OFF of the switch  223   b . When the switch  223   b  is ON, DC current is applied to the first electrode  223 . Electrostatic acts between the first electrode  223  and the substrate W by the current applied to the first electrode  223  and the substrate W is adsorbed to the support plate  220  by the electrostatic. 
         [0061]    The heater  225  is disposed below the first electrode  223 . The heater  225  is electrically connected to a second power  225   a . The heater  225  generates heat by resisting the current applied from the second power  225   a . The generated heat is transferred to the substrate W through the support plate  220 . The substrate W is maintained at a predetermined temperature by the heat generated by the heater  225 . The heater  225  includes a spiral coil. 
         [0062]    The base plate  230  is disposed below the support plate  220 . The bottom surface of the support plate  220  and the top surface of the base plate  230  may adhere to each other through a brazing process using a filler  235  as a medium. The base plate  230  may include a conductive material. For example, the base plate  230  may be provided with an aluminum material. The base plate  230  may include an electrode. The top surface of the base plate  230  may be stepped to allow a center heating area to be disposed higher than an edge heating area. The top surface center heating area of the base plate  230  has an area corresponding to the bottom of the substrate  220  and adheres to the bottom of the support plate  220 . A circulation passage  231 , a cooling member  232 , and a second supply passage  233  are formed at the base plate  230 . 
         [0063]    The circulation passage  231  is provided as a path through which a heat transfer medium circulates. The circulation passage  231  may be formed with a spiral form in the base plate  230 . Or, the circulation passage  231  may be disposed to allow passages having ring forms of different radii to have the same center. The circulation passages  231  may communicate with each other. The circulation passages  231  are formed at the same height. 
         [0064]    The cooling member  232  cools the body. The cooling member  232  is provided as a path through which a cooling fluid circulates. The cooling member  232  may be formed with a spiral form in the base plate  230 . Additionally, the cooling member  232  may be disposed to allow passages having ring forms of different radii to have the same center. The cooling members  232  may communicate with each other. The cooling member  232  may have a greater section area than the circulation passage  231 . The cooling members  232  are formed at the same height. The cooling member  232  may be disposed below the circulation passage  231 . 
         [0065]    The second supply passage  233  extends from the first circulation passage  231  to the top and is provided at the top surface of the base plate  230 . The second supply passage  233  is provided in correspondence to the number of the first supply passages  221  and connects the first circulation passage  231  and the first supply passage  221 . 
         [0066]    The circulation passage  231  is connected to a heat transfer medium storage unit  231   a  through a heat transfer medium supply line  231   b . The heat transfer medium storage unit  231   a  stores a heat transfer medium. The heat transfer medium includes inert gas. According to an embodiment of the present invention, the heat transfer medium includes He gas. The He gas is supplied to the circulation passage  231  through the supply line  231   b , sequentially passes through the second supply passage  233  and the first supply passage  221 , and is supplied to the bottom of the substrate W. The He gas serves as a medium by which a heat transferred from plasma to the substrate W is transferred to the electrostatic chuck  210 . 
         [0067]    The cooling member  232  is connected to the cooling fluid storage unit  232   a  through the cooling fluid supply line  232   c . The cooling fluid storage unit  232   a  stores a cooling fluid. A cooler  232   b  may be provided in the cooling fluid storage unit  232   a . The cooler  232   b  cools a cooling fluid to a predetermined temperature. Unlike this, the cooler  232   b  may be installed on the cooling fluid supply line  232   c . The cooling fluid supplied to the cooling member  232  through the cooling fluid supply line  232   c  cools the base plate  230  as circulating along the cooling member  232 . As the base plate  230  is cooled and thus cools the support plate  220  and the substrate W together, the substrate W is maintained at a predetermined temperature. 
         [0068]    The base plate  230  may include a metallic plate. For example, the entire base plate  230  may be provided with a metallic plate. The base plate  230  may be electrically connected to a third power  235   a . The third power  235   a  may be provided as a high-frequency power generating high-frequency power. The high-frequency power may be provided as RF power. The base plate  230  receives a high-frequency power from the third power  235   a . Due to this, the base plate  230  may function as an electrode. 
         [0069]    A focus ring  240  is disposed at an edge area of the electrostatic chuck  210 . The focus ring  240  has a ring form and is disposed along the circumference of the support plate  220 . The top surface of the focus ring  240  may be stepped to allow the outer part  240   a  to be higher than the inner part  240   b . The top surface inner part  240   b  of the focus ring  240  and the top surface of the support plate  220  may be positioned at the same height. The top surface inner part  240   b  of the focus ring  240  supports an edge area of the substrate W disposed at the outer side of the support plate  220 . The outer part  240   a  of the focus ring  240  is provided to surround the edge area of the substrate W. The focus ring  240  controls an electromagnetic field thereby uniformly distributing the density of plasma in an entire area of the substrate W. Due to this, plasma is uniformly formed over an entire area of the substrate W, so that each area of the substrate W may be etched uniformly. 
         [0070]    The lower cover  250  is disposed at the bottom end part of the support unit  200 . The lower cover  250  is disposed spaced from the bottom surface of the chamber  100  to the top. A space having the top surface open is formed in the lower cover  250 . The external radius of the lower cover  250  may have the same length as the external radius of the base plate  230 . A lift pin module (not shown) moving the transferred substrate W from the external conveying member to the electrostatic chuck  210  may be disposed in an inner space of the lower cover  250 . The bottom surface of the lower cover  250  may be provided with a metallic material. 
         [0071]    The lower cover  250  has a connection member  253 . The connection member  253  connects the outer surface of the lower cover  250  and the inner wall of the chamber  100 . A plurality of connection members  253  are provided at the outer surface of the lower cover  250  at regular intervals. The connection member  253  supports the support unit  200  in the chamber  100 . Additionally, as the connection member  253  is connected to the inner wall of the chamber  253 , the lower cover  250  is electrically grounded. A first power line  223   c  connected to the first power  223   a , a second power line  225   c  connected to the second power  225   a , a third power line  235   c  connected to the third power  235   a , a heat transfer medium supply line  231   b  connected to the heat transfer medium storage unit  231   a , and a cooling fluid supply line  232   c  connected to the cooling fluid storage unit  232   a  extend into the lower cover  250  through an inner space of the connection member  253 . 
         [0072]    The plate  270  is disposed between the electrostatic chuck  210  and the lower cover  250 . The plate  270  covers the top surface of the lower cover  250 . The plate  270  is provided as a section area corresponding to the base plate  230 . The plate  270  may include an insulator. The plate  270  electrically insulates the base plate  230  from the lower cover  250 . 
         [0073]    A plasma source generates plasma from a process gas. The plasma source may provide capacitively coupled plasma (CCP) or inductively coupled plasma (ICP). 
         [0074]    Hereinafter, the case that a plasma source is provided as capacitively coupled plasma (CCP) in the substrate treating device  10  is described. Thus, the plasma source includes a shower head  300 . Unlike this, the plasma source may be provided as inductively coupled plasma (ICP). 
         [0075]    The shower head  300  is disposed above the support unit  200  in the chamber  100 . The shower head  300  is disposed to face the support unit  200 . 
         [0076]    The shower head  300  includes a gas distribution plate  310  and a support part  330 . The gas distribution plate  310  is spaced a predetermined distance from the top surface of the chamber  100  to the bottom. A predetermined space is formed between the gas distribution plate  310  and the top surface of the chamber  100 . The gas distribution plate  310  may be provided in a plate form with a uniform thickness. The bottom surface of the gas distribution plate  310  may be polarized so as to prevent arc generation by plasma. The section of the gas distribution plate  310  may be provided to have the same form and section area as the support unit  200 . The gas distribution plate  310  includes a plurality of injection holes  311 . The injection hole  311  vertically penetrates the top and bottom surfaces of the gas distribution plate  310 . The gas distribution plate  310  includes a metallic material. The gas distribution plate  310  may be electrically connected to the fourth power  351 . The fourth power  351  may be provided as high-frequency power. Unlike this, the gas distribution plate  310  may be electrically grounded. The gas distribution plate  310  may be electrically connected to the fourth power  351  or grounded, thereby functioning as an electrode. 
         [0077]    The support part  330  supports a side part of the gas distribution plate  310 . The support part  330  has a top end connected to the top surface of the chamber  100  and a bottom end connected to a side part of the gas distribution plate  310 . The support part  330  may include a non-metallic material. 
         [0078]    The shower head  300  serves as an electrode as power is provided. The shower head  300  and the base plate  230  of the support unit  200  may serve as an upper electrode and a lower electrode, respectively. The upper electrode and the lower electrode may be disposed vertically parallel to each other in the chamber  100 . One of the upper electrode and the lower electrode may apply high-frequency power and the other one may be grounded electrically. An electromagnetic field may be formed in a space between the both electrodes and a process gas supplied to this space may be excited to a plasma state. By using this plasma, a substrate treating process is performed. 
         [0079]    For example, high-frequency power may be applied to the lower electrode and the upper electrode may be grounded electrically. Unlike this, high-frequency power may be applied to the both the upper electrode and the lower electrode. Due to this, an electromagnetic field occurs between the upper electrode and the lower electrode. The generated electromagnetic field excites a process gas provided to the inside of the chamber  100  to a plasma state. 
         [0080]    The gas supply unit  400  supplies a process gas to the inside of the chamber  100 . The gas supply unit  400  includes a gas supply nozzle  410  a gas supply line  420 , and a gas storage unit  430 . The gas supply nozzle  410  is installed at the top surface center part of the chamber  100 . An injector is formed at the bottom of the gas supply nozzle  410 . The injector supplies a process gas into the chamber  100 . The gas supply line  420  connects the gas supply nozzle  410  and the gas storage unit  430 . The gas supply line  420  supplies a process gas stored in the gas storage unit  430  to the gas supply nozzle  410 . A valve  421  is installed at the gas supply line  420 . The valve  421  opens/closes the gas supply line  420  and adjusts the flow rate of a process as supplied through the gas supply line  420 . 
         [0081]    A baffle unit  500  is disposed between the inner wall of the chamber  100  and the support unit  200 . A baffle  510  is provided in an annular ring form. A plurality of through holes  511  are formed in the baffle  510 . A process gas provided into the chamber  100  passes through the through holes  511  of the baffle  510  and is discharged to the discharge hole  102 . The flow of a process gas may be controlled according to the form of the baffle  510  and the forms of the through holes  511 . 
         [0082]    Hereinafter, a method of manufacturing the support unit of  FIG. 1  will be described.  FIG. 4  is a schematic separation diagram illustrating components of the support unit of  FIG. 1 .  FIG. 5  is a flowchart illustrating a method of manufacturing a support unit. For convenience of drawing, grooves, protrusions, projection parts, and supply passages at the top of the support plate  220  are omitted. 
         [0083]    The electrostatic chuck  210  of a support unit includes a support plate  220 , a base plate  230 , and a bonding part. Herein, the bonding part is a bonding layer bonded through a brazing process using the filler  235  as a medium. 
         [0084]    First, a metallic layer  226  is deposited at the bottom surface of the support plate  220  formed of a non-conductive material in operation S10. The metallic layer  226  may be deposited at the bottom surface of the support plate  220  through vacuum deposition or plating. The metallic layer  226  may be one of Ti, Ni, and Ag. 
         [0085]    A filler  235  is provided between the support plate  220  and the base plate  230  formed of a conductive material in operation S20. The filler  235  may be provided with a metallic material. For example, the filler  235  may include AL. A brazing process is performed by using the filler  235  as a medium in operation S30. To briefly explain the brazing process, after the filler  235  is inserted between the support plate  220  and the base plate  230  to be bonded and then is heated to a temperature sufficient for melting a metal, as the melted filler  235  is cooled, a storing bonding part is formed. The support plate  220  and the base plate  230  are coupled to each other through the brazing. By this, as the support plate  220  and the base plate  230  are coupled to each other, the electrostatic chuck  210  has a great heat resistance during a high temperature process. 
         [0086]    For reference, the filler  235  may be provided with a metal having a lower melting point than the metallic layer  226  and the base plate  230  at the bottom of the support plate  220 . 
         [0087]    Moreover, in order to minimize a heat stress by a thermal expansion rate difference between a base plate and a support plate, the base plate may be provided with a conductive composite material obtained by mixing a conductive material and an added material. The added material may be a material that expands less in consideration of a thermal expansion rate difference between a conductive material and a material of a support plate. For example, the conductive material may include Ti or Al and the added material may include one of SiC, Al 2 O 3 , Si, graphite, and glass fiber. The conductive composite material may include the added material of 10% to 70%. 
         [0088]    As mentioned above, as a base plate is manufactured with a conductive composite material, when the support plate  220  and the base plate  230  are coupled by brazing, a heat stress by a thermal expansion rate difference between the support plate  220  and the base plate  230  may be reduced. By reducing the heat stress due to a thermal expansion rate difference, a crack phenomenon and a bending phenomenon in the support plate  220  due to a thermal expansion difference may be prevented. 
         [0089]    In the above embodiment, the case that the support plate  220  and the base plate  230  are coupled to each other through brazing is described. Unlike this, the support plate  220  and the base plate  230  are coupled to each other through different various methods. For example, an adhesive layer may be provided between the support plate  220  and the base plate  230 . 
         [0090]      FIG. 6  is a view illustrating a modified embodiment of an electrostatic chuck. 
         [0091]    An electrostatic chuck  210   a  shown in  FIG. 6  includes a support plate  220 , a base plate  230 , and a bonding part. Herein, the bonding part is an adhesive layer adhered through a brazing process using the filler  235  as a medium. The difference from the above electrostatic chuck is that a metal mesh  236  is inserted into the filler  235  so as to reduce the degree of expansion resulting from a thermal expansion rate difference. For example, the metal mesh  236  may have a porosity of 20% to 80%. 
         [0092]    Although a bonding part may be provided with the metal mesh  236  inserted into the filler  235  in this embodiment, as another example, the filler  235  itself may be provided in a mesh form. 
         [0093]      FIGS. 7 and 8  are views illustrating a modified embodiment of an electrostatic chuck. 
         [0094]    Electrostatic chucks  210   b  and  210   c  shown in  FIGS. 7 and 8 , without a filler as a medium, a metallic layer  226  and a base plate  230  at the bottom of a support plate  220  may be coupled by brazing. Uneven parts  239  and  229  may be provided to the metallic layer  226  and the base plate  230  so as to minimize a stress due to thermal expansion. The uneven parts  239  and  229  may be formed at the top surface of the base plate  230  or the bottom of the metallic layer  226  as shown in  FIGS. 7 and 8 . For example, the uneven parts  239 , 229  may be provided in a mesh form or an embossing form. 
         [0095]    According to an embodiment of the present invention, a support unit having a strong thermal durability may be provided. 
         [0096]    According to an embodiment of the present invention, by minimizing a heat stress due to a thermal expansion rate difference between a support plate and a base plate, a crack phenomenon and a bending phenomenon in the support plate may be prevented. 
         [0097]    The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true spirit and scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.