Patent Publication Number: US-2005133157-A1

Title: Temperature controller system for controlling temperature of an object and an apparatus including same

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      This application claims priority under 35 USC § 119 to Korean Patent Application No. 2003-94360, filed on Dec. 22, 2003, the contents of which are herein incorporated by reference in its entirety for all purposes.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a temperature controller system for controlling temperature of an object, and an apparatus including the temperature controller system. More particularly, the present invention relates to a temperature controller system for controlling the temperature of an area in which a wafer is disposed, and an etching apparatus for uniformly etching a surface of the wafer using the temperature controller system.  
      2. Description of the Related Arts  
      Generally, a semiconductor device may be manufactured by stacking a semiconductor material, a conductive material and a non-conducting material on a semiconductor substrate and then by patterning the stacked layers. A process for forming a pattern may include a photolithography process for forming a photoresist pattern which is produced by exposing and developing a photosensitive photoresist film formed on an underlying layer on the semiconductor substrate using a mask. Then, an etching process is provided for etching the underlying layer using the photoresist pattern as an etching mask. The etching process may be carried out for manufacturing the semiconductor device. To form a pattern by selectively removing an object material in the etching process, various etching techniques have been developed and diverse etching equipments have been used.  
      The etching techniques may be classified into isotropic etching techniques and anisotropic etching techniques. The isotropic etching technique is one in which a layer is etched in a specific direction. Basically, it is an etching technique using a chemical reaction to implement the isotropic etching technique. A wet etching technique and a plasma etching technique can be employed to implement the isotropic etching technique. The anisotropic etching technique can use a reactive ion etching (RIE) technique. In the RIE process, reaction gases are ionized in a processing chamber. The ionized gases are electrically accelerated so that a specified layer is generally etched in the direction of a specified electric field. Plasma for activating the reaction gases is used in a dry etching technique. A high-frequency electric field is applied to the reaction gases to form the plasma.  
      In particular, a voltage is applied between upper and lower electrodes disposed in a plasma chamber to form an electric field therein. A reaction gas is supplied to a space between the upper and lower electrodes under a low pressure. The voltage may be generated using an alternating current, such as a high-frequency alternating current, or a direct current. When the direct current is used, the flow of the direct current may be cut off so that an insulation material for covering the electrodes is not used. When an alternating current is used, it is not necessary that both ends of the electrodes include a conductive material. Sufficient energy is provided to electrons between the upper and lower electrodes by vibration of the electric field so that the electrons collide against neutral atoms to create charged particles. The electrons generated in the space between the upper and lower electrodes collide against the neutral atoms to generate decomposition and luminescence, thereby creating more ions and electrons. Positive ions are accelerated by the electric field to collide against the electrodes, thereby creating additional electrons.  
      Meanwhile, when the charged particles are increased, the charged particles having different polarities collide with each other so that the total number of charged particles is decreased. When numbers of the charged particles generated in the etching process are balanced with numbers of the charged particles converted into the neutral particles, the plasma has a stable state. The stable plasma comprises partially ionized particles and neutral particles under a low pressure.  
       FIG. 1  is a cross sectional view illustrating a conventional plasma etching apparatus. Referring to  FIG. 1 , a conventional plasma etching apparatus includes an etching chamber  1  into which a reaction gas is introduced. An electrostatic chuck (ESC)  2  on which a wafer is disposed is mounted on a bottom face of the etching chamber  1 . A lower electrode (not shown) is disposed under the ESC  2 .  
      An upper electrode  3  for applying a high-frequency voltage to the reaction gas to form plasma is disposed at an upper portion of the etching chamber  1 . A cooling plate  8  for cooling the upper electrode  3  is mounted on the upper electrode  3 . A gas-diffusing ring  7  for providing the reaction gas into the etching chamber  1  is disposed beneath an edge of the upper electrode  3 .  
      A matcher  6  for applying a radio frequency (RF) power to the upper electrode  3  is disposed over the etching chamber  1 . The matcher  6  is disposed over the upper electrode  3 . A vacuum pump  5  for providing vacuum into the etching chamber  1  is connected to a lower face of the etching chamber  1 . A vacuum sensor  4  is attached to a sidewall of the etching chamber  1 .  
      Since the wafer is heated at a high temperature in the etching process, controlling the temperature of the wafer by cooling is required. Thus, a temperature controller is provided to the ESC  2 .  
       FIG. 2  is a perspective view illustrating a conventional temperature controller. Referring to  FIG. 2 , the conventional temperature controller includes a cooling line  10  formed in the ESC  2 . The cooling line  10  has a spiral single line that extends from an edge portion of the ESC  2  to a central portion of the ESC  2  through the middle portion of the ESC  2 . An edge portion of the cooling line  10 , positioned at the edge portion of the ESC  2 , corresponds to an inlet in which a refrigerant enters. A central portion of the cooling line  10 , positioned at the central portion of the ESC  2 , corresponds to an outlet from which the refrigerant exits.  
      A refrigerant bath  11  in which the refrigerant is contained is connected to the inlet of the cooling line  10 . A valve  12  for controlling flux of the refrigerant is mounted on the inlet of the cooling line  10 . A temperature sensor  13  for detecting a temperature of the refrigerant is mounted on the outlet of the cooling line  10 .  
      The conventional temperature controller cools the wafer disposed on the ESC  2  using the refrigerant that flows through the single cooling line  10 . Since the cooling line  10  is a single line, the conventional temperature controller may not separately control the central portion, the middle portion and the edge portion of the ESC  2 . Particularly, the edge portion of the ESC  2 , adjacent to the inlet of the cooling line  10 , is cooled more rapid than the central portion of the ESC  2 . As a result, the edge portion of the ESC  2  has a temperature below that of the central portion of the ESC  2 . An etching rate is inversely proportional to the temperature so that the edge portion of the wafer has an etching rate greater than that of the central portion of the wafer. Accordingly, the wafer may not be etched uniformly.  
      To overcome the above problem, a conventional temperature controller illustrated in  FIG. 3  is disclosed in Japan Laid Open publication No. 1993-243191.  
      Referring to  FIG. 3 , a conventional temperature controller includes first, second and third refrigerant baths  21 ,  22  and  23 . A first cooling line  31  is connected between the first refrigerant bath  21  and an edge portion of an ESC  50 . A second cooling line  32  is connected between the second refrigerant bath  22  and a middle portion of the ESC  50 . A third cooling line  33  is connected between the third refrigerant bath  23  and a central portion of the ESC  50 . First, second and third valves  41 ,  42  and  43  are mounted on inlets of the first, second and third cooling lines  31 ,  32  and  33 , respectively. Also, first, second and third temperature sensors  61 ,  62  and  63  are installed at the first, second and third cooling lines  31 ,  32  and  33 , respectively. First, second and third controllers  71 ,  72  and  73  control opening angles of the first, second and third valves  41 ,  42  and  43  in accordance with temperatures detected by the first, second and third temperature sensors  61 ,  62  and  63 .  
      The conventional temperature controller separately provides different refrigerants from the first, second and third refrigerant baths  21 ,  22  and  23  to the edge portion, the middle portion and the central portion of the ESC  50  through the first, second and third cooling lines  31 ,  32  and  33 , respectively. Thus, the conventional temperature controller may separately control the edge portion, the middle portion and the central portion of the ESC  50 .  
      However, although the conventional temperature controller controls the temperature of the ESC by regions, one to one correspondence of the baths to the regions is required. When the numbers of the baths are increased, the temperature controller has complex structure and thus, high manufacturing cost of the temperature controller is resulted.  
      Also, the flux of the different refrigerants from the separate baths may not be readily controlled. Further, the separate baths may be independently managed.  
     SUMMARY OF THE INVENTION  
      The present invention provides a temperature controller capable of controlling temperatures of a stage by regions using one bath.  
      The present invention also provides an etching apparatus having the above-mentioned temperature controller.  
      A temperature controller system for controlling the temperature of an object in accordance with one aspect of the present invention includes a bath for containing a refrigerant. One cooling line has a first end connected to the bath and a second end opposite to the first end. The second end branches off into a plurality of diverged lines, e.g., first, second and third diverged lines. The first diverged line is connected to an edge portion of the object. The second diverged line is connected to a middle portion of the object. The third diverged line is connected to a central portion of the object. A plurality of valves for controlling a flux of the refrigerants are mounted on inlets of the plurality of diverged lines, respectively, through which the refrigerant flows to the object. A plurality of temperature sensors, e.g., first, second and third temperature sensors for detecting temperatures of the refrigerant are mounted on outlets of, e.g., the first, second and third diverged lines, respectively, through which the refrigerant flows from the object. A controller controls opening angles of the plurality of valves in accordance with the temperatures of the refrigerant detected by the first, second and third temperature sensors.  
      An apparatus in accordance with another aspect of the present invention includes an etching chamber into which a reaction gas for forming a plasma is introduced. An electrostatic chuck (ESC) on which a wafer is disposed is installed on a bottom face of the etching chamber. An upper electrode for applying a voltage to the reaction gas to form the plasma is disposed at an upper portion of the etching chamber. A cooling plate is mounted on the upper electrode. A temperature controller is connected to the ESC. The temperature controller includes a bath for containing a refrigerant. One cooling line has a first end connected to the bath and a second end opposite to the first end. The second end branches off into first, second and third diverged lines. The first diverged line is connected to an edge portion of the ESC. The second diverged line is connected to a middle portion of the ESC. The third diverged line is connected to a central portion of the ESC. First, second and third valves for controlling flux of the refrigerant are mounted on inlets of the first, second and third diverged lines, respectively, through which the refrigerant flows to the ESC. First, second and third temperature sensors for detecting temperatures of the refrigerant are mounted on outlets of the first, second and third diverged lines, respectively, through which the refrigerant flows from the ESC. A controller controls opening angles of the first, second and third valves in accordance with the temperatures of the refrigerant detected by the first, second and third temperature sensors.  
      An apparatus in accordance with still another aspect of the present invention includes an etching chamber into which a reaction gas for forming a plasma is introduced. An ESC on which a wafer is disposed is installed on a bottom face of the etching chamber. An upper electrode for applying a voltage to the reaction gas to form the plasma is disposed at an upper portion of the etching chamber. A cooling plate is mounted on the upper electrode. A temperature controller is connected to the cooling plate. The temperature controller includes a bath for containing a refrigerant. One cooling line has a first end connected to the bath and a second end opposite to the first end. The second end branches off into first, second and third diverged lines. The first diverged line is connected to an edge portion of the cooling plate. The second diverged line is connected to a middle portion of the cooling plate. The third diverged line is connected to a central portion of the cooling plate. First, second and third valves for controlling flux of the refrigerants are mounted on inlets of the first, second and third diverged lines, respectively, through which the refrigerant flows to the cooling plate. First, second and third temperature sensors for detecting temperatures of the refrigerants are mounted on outlets of the first, second and third diverged lines, respectively, through which the refrigerant flows from the cooling plate. A controller controls opening angles of the first, second and third valves in accordance with the temperatures of the refrigerant detected by the first, second and third temperature sensors.  
      An apparatus in accordance with still another aspect of the present invention includes an etching chamber into which a reaction gas for forming a plasma is introduced. An ESC on which a wafer is disposed is installed on a bottom face of the etching chamber. A first temperature controller is connected to the ESC. An upper electrode for applying a voltage to the reaction gas to form a plasma is disposed at an upper portion of the etching chamber. A cooling plate is mounted on the upper electrode. A second temperature controller is connected to the cooling plate. Each of the first and second temperature controllers includes a bath in which a refrigerant is contained. One cooling line has a first end connected to the bath and a second end opposite to the first end. The second end branches off into each of first, second and third diverged lines. Each of the first diverged lines is connected to an edge portion of the ESC and the cooling plate. Each of the second diverged lines is connected to a middle portion of the ESC and the cooling plate. Each of the third diverged lines is connected to a central portion of the ESC and the cooling plate. First, second and third valves for controlling flux of the refrigerant are mounted on inlets of the first, second and third diverged lines, respectively, through which the refrigerant flows to the ESC or the cooling plate. First, second and third temperature sensors for detecting temperatures of the refrigerants are mounted on outlets of the first, second and third diverged lines, respectively, through which the refrigerant flows from the ESC or the cooling plate. A controller controls opening angles of the first, second and third valves in accordance with the temperatures of the refrigerant detected by the first, second and third temperature sensors.  
      According to embodiments of the present invention, the temperatures of the object by regions may be readily controlled using one bath. Thus, the temperature controller has simple structure, and manufacturing cost of the temperature controller is decreased. Also, the flux of the refrigerants from one bath may be readily controlled. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above objects and advantages of the present invention will become more apparent by describing preferred embodiments in detail with reference to the attached drawings in which:  
       FIG. 1  is a cross sectional view illustrating a conventional etching apparatus;  
       FIG. 2  is a perspective view illustrating a conventional temperature controller;  
       FIG. 3  is a partially cross sectional view illustrating an etching apparatus having a conventional temperature controller;  
       FIG. 4  is a cross sectional view illustrating a temperature controller in accordance with a first embodiment of the present invention;  
       FIG. 5  is a cross sectional view illustrating an ESC in which the temperature controller in  FIG. 4  is employed;  
       FIG. 6  is a cross sectional view illustrating an etching apparatus in accordance with a second embodiment of the present invention;  
       FIG. 7  is a cross sectional view illustrating an etching apparatus in accordance with a third embodiment of the present invention; and  
       FIG. 8  is a cross sectional view illustrating an etching apparatus in accordance with a fourth embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown.  
     Embodiment 1  
      Referring to  FIG. 4 , a temperature controller system  100  in accordance with the present embodiment of the present invention includes only one refrigerant bath  110  for containing a refrigerant. One cooling line  120  has a first end and a second end. The first end of the cooling line  120  is connected to the refrigerant bath  110 . The second end of the cooling line  120  branches off into first, second and third diverged lines  131 ,  132  and  133 .  
      The first diverged line  131  is connected to an edge portion of an object  240 , for example an electrostatic chuck on which a wafer is disposed. The second diverged line  132  is connected to a middle portion of the object  240 . The third diverged line  133  is connected to a central portion of the object  240 .  
      Referring to  FIG. 5 , the first, second and third diverged lines  131 ,  132  and  133  are arrayed in concentric circles on the object  240 . In particular, the first diverged line  131  formed on the edge portion of the object  240  has a circular shape having a first diameter. The second diverged line  132  formed on the middle portion of the object  240  has a circular shape having a second diameter less than the first diameter. The third diverged line  133  formed on the central portion of the object  240  has a circular shape having a third diameter less than the second diameter. Alternatively, the first, second and third diverged lines  131 ,  132  and  133  may be arrayed in spiral shapes. Also, the first, second and third diverged lines  131 ,  131  and  133  may have rectangular or triangular shapes.  
      Referring again to  FIG. 4 , first, second and third valves  141 ,  142  and  143  are mounted on inlets of the first, second and third diverged lines  131 ,  132  and  133 , respectively, through which the refrigerant flows to the object  240 . Particularly, the first valve  141  is mounted on the inlet of the first diverged line  131 . The second valve  142  is mounted on the inlet of the second diverged line  132 . The third valve is mounted on the inlet of the third diverged line  133 .  
      According to the present embodiment, although the temperature controller system  100  has one refrigerant bath  110 , the first, second and third valves  141 ,  142  and  143  separately control flux of the refrigerants flowing through the respective first, second and third diverged lines  131 ,  132  and  133 .  
      The first, second and third diverged lines  131 ,  132  and  133  have outlets, respectively, through which the refrigerants flow from the object  240 . First, second and third temperature sensors  151 ,  152  and  153  are installed on the outlets of the first, second and third diverged lines  131 ,  132  and  133 , respectively.  
      A controller  160  controls the opening angles of the first, second and third valves  141 ,  142  and  143  in accordance with the temperatures of the refrigerants detected by the first, second and third temperature sensors  151 ,  152  and  153 .  
      The refrigerants flow from the refrigerant bath  110  into the first, second and third diverged lines  131 ,  132  and  133  through the cooling line  120 . Here, the first, second and the third valves  141 ,  142  and  143  separately control the flux of the refrigerants flowing through the first, second and third diverged lines  131 ,  132  and  133 , respectively. Also, the first, second and third temperature sensors  151 ,  152  and  153  detect the temperatures of the refrigerants that exit from the respective first, second and third diverged lines  131 ,  132  and  133 .  
      The temperatures of the refrigerants are transmitted to the controller  160 . The controller  160  properly adjusts the opening angles of the first, second and third valves  141 ,  142  and  143  to uniformly cool the object  240 .  
      For example, when a central temperature of the object  240  is higher than an edge temperature of the object  240 , the controller  160  controls the third valve  143  to open wider than the first valve  141 , thereby increasing the flux of the refrigerant flowing through the third diverged line  133  so that it is greater than that of the refrigerant flowing through the first diverged line  131 . As a result, the object  240  can be substantially uniformly cooled.  
     Embodiment 2  
      Referring to  FIG. 6 , an etching apparatus  200  in accordance with the present embodiment of the present invention includes the temperature controller system  100  which is disposed in accordance with the first embodiment. Accordingly, identical reference numerals refer to substantially identical elements and a further illustration of the temperature controller system  100  is omitted.  
      The etching apparatus  200  includes an etching chamber  210  into which a reaction gas for forming a plasma is introduced. An electrostatic chuck  240  on which a wafer W is disposed is mounted on a bottom face of the etching chamber  210 . A lower electrode (not shown) is disposed under the electrostatic chuck  240 . The temperature controller system  100  is connected to the electrostatic chuck  240 .  
      An upper electrode  220  for applying a high voltage to the reaction gas to form the plasma is disposed at an upper portion of the etching chamber  210 . A cooling plate  230  for cooling the upper electrode  220  is mounted on the upper electrode  220 . A gas-diffusing ring  270  for uniformly diffusing the reaction gas into the etching chamber  210  is disposed beneath an edge of the upper electrode  220 .  
      An RF matcher  260  for applying an RF power to the upper electrode  220  is disposed over the upper electrode  210 . A vacuum pump  250  for providing vacuum into the etching chamber  210  is connected to a lower portion of the etching chamber  210 . A vacuum sensor  280  is attached to a sidewall of the etching chamber  210 .  
     Embodiment 3  
      Referring to  FIG. 7 , an etching apparatus  200  in accordance with the present embodiment of the present invention includes the temperature controller system  100  designed in accordance with the first embodiment. Accordingly, identical reference numerals refer to substantially identical elements and a further illustration of the temperature controller system  100  is omitted.  
      The etching apparatus  300  includes an etching chamber  310  into which a reaction gas for forming a plasma is introduced. An electrostatic chuck  340  on which a wafer W is disposed is mounted is disposed on the bottom face of the etching chamber  310 . A lower electrode (not shown) is disposed under the electrostatic chuck  340 .  
      An upper electrode  320  for applying a high voltage to the reaction gas to form the plasma is disposed at an upper portion of the etching chamber  310 . A cooling plate  330  for cooling the upper electrode  320  is mounted on the upper electrode  320 . The temperature controller system  100  is connected to the cooling plate  330 .  
      A gas-diffusing ring  370  for uniformly diffusing the reaction gas into the etching chamber  310  is disposed beneath an edge of the upper electrode  320 . An RF matcher  360  for applying an RF power to the upper electrode  320  is disposed over the upper electrode  310 . A vacuum pump  350  for providing vacuum into the etching chamber  310  is connected to a lower portion of the etching chamber  310 . A vacuum sensor  380  is attached to a sidewall of the etching chamber  310 .  
     Embodiment 4  
      Referring to  FIG. 8 , an etching apparatus  400  in accordance with the present embodiment of the present invention includes an etching chamber  410  into which a reaction gas for forming a plasma is introduced. An electrostatic chuck  440  on which a wafer W is disposed is mounted on a bottom face of the etching chamber  410 . A lower electrode (not shown) is disposed under the electrostatic chuck  440 . A first temperature controller system  100   a  is connected to the electrostatic chuck  440 . Here, the first temperature controller system  100   a  has elements substantially identical to those of the temperature controller system  100  in accordance with the first embodiment. Thus, an illustration of the first temperature controller system  100   a  is omitted.  
      An upper electrode  420  for applying a high voltage to the reaction gas to form the plasma is disposed at an upper portion of the etching chamber  410 . A cooling plate  430  for cooling the upper electrode  420  is mounted on the upper electrode  420 . A second temperature controller system  100   b  is connected to the cooling plate  430 . Here, the second temperature controller system  100   b  also has elements substantially identical to those of the temperature controller system  100  in accordance with the first embodiment. Thus, an illustration of the second temperature controller system  100   b  is omitted.  
      A gas-diffusing ring  470  for uniformly diffusing the reaction gas into the etching chamber  410  is disposed beneath an edge of the upper electrode  420 . An RF matcher  460  for applying an RF power to the upper electrode  420  is disposed over the upper electrode  410 . A vacuum pump  450  for providing vacuum into the etching chamber  410  is connected to a lower portion of the etching chamber  410 . A vacuum sensor  480  is attached to a sidewall of the etching chamber  410 .  
      According to the present invention, the valves may be mounted on the diverged lines from one refrigerant bath so that the temperatures of the object by regions may be readily controlled using the temperature controller system that has only one bath as previously described. Thus, the temperature controller system has simple structure, and the manufacturing cost of the temperature controller system can be decreased.  
      Also, the etching apparatus having the temperature controller system may etch the wafer by a uniform thickness.  
      Having described the preferred embodiments of the present invention, it is noted that modifications and variations can be made by persons skilled in the art in light of the above teachings. It is therefore to be understood that changes may be made in the particular embodiment of the present invention disclosed which is within the scope and the spirit of the invention outlined by the appended claims.