Abstract:
A plasma processing apparatus for generating plasma in a chamber maintained in a vacuum state and processing a substrate using the plasma. The plasma processing apparatus includes a refrigerant channel for circulating a refrigerant formed in a shower head, thereby easily controlling the temperature of the shower head and improving the reproducibility of plasma treatment.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to Korean Patent Application No. 10-2004-0110832 filed on Dec. 23, 2004, Korean Patent Application No. 10-2004-0110937 filed on Dec. 23, 2004, and Korean Patent Application No. 10-2004-0111019 filed on Dec. 23, 2004, all of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a plasma processing apparatus, which generates plasma in a chamber maintained in a vacuum state and processes a substrate using the plasma. 
     2. Description of the Related Art 
     Plasma processing apparatuses, which process the surface of a substrate using plasma, have been widely used in a process for manufacturing a semiconductor device and a liquid crystal display device. The plasma processing apparatuses include a plasma etching apparatus for performing etching of a substrate and a plasma Chemical Vapor Deposition (CVD) apparatus for performing CVD of a substrate. 
     As shown in  FIG. 1 , a plasma processing apparatus  1  comprises two flat plate-type electrodes  10  and  20  located in parallel such that they face each other. A substrate S is mounted on the lower electrode  20 . Accordingly, the lower electrode  20  may be referred to as “a substrate mount”. 
     Further, internal elevating pins  30  and external elevating bars (not shown) for assisting the carrying of the substrate S into and out of the plasma processing apparatus  1  are provided in the plasma processing apparatus  1 , as shown in  FIG. 1 . The internal elevating pins  30  are located in through holes  22  formed through edges of the lower electrode  20 , and move vertically in the through holes  22 . 
     The external elevating bars are provided at the outside of the lower electrode  20 . That is, the external elevating bars are located in spaces formed between side walls of the lower electrodes  20  and the side walls of the plasma processing apparatus  1 , and move vertically. 
     An exhaust unit  40  for exhausting inner gas to the outside is formed through the plasma processing apparatus  1 . The exhaust unit  40  removes gas in the plasma processing apparatus  1  by suction and maintains a vacuum state of the plasma processing apparatus  1  using a pump (not shown) provided at the outside of the plasma processing apparatus  1 . 
     The upper electrode  10  is located at a position facing the lower electrode  20 . The upper electrode  10  serves as a process gas supply unit for supplying process gas to a space between the upper and lower electrodes  10  and  20  as well as an electrode. Accordingly, as shown in  FIG. 1 , a shower head  12  is connected to the lower portion of the upper electrode  10 . The shower head  12  has a plurality of process gas diffusing holes  14  having a fine diameter. The shower head  12  uniformly supplies the process gas to the space between the upper and lower electrodes  10  and  20 . The process gas supplied to the space between the upper and lower electrodes  10  and  20  is converted into plasma by high-frequency power applied to the upper and lower electrodes  10  and  20 , and the plasma processes the surface of the substrate S. 
     A refrigerant channel  16  for circulating a refrigerant therethrough is formed in the upper electrode  10 . The refrigerant channel  16  passes through the upper electrode  10  in the horizontal direction, and is uniformly disposed throughout all regions of the upper electrode  10 . One end of the refrigerant channel  16  is connected to a refrigerant supply pipe  17  communicating with the outside, and the other end of the refrigerant channel  16  is connected to a refrigerant collection pipe  18 . Accordingly, the refrigerant channel  16  receives a new refrigerant from the refrigerant supply pipe  17  and returns the waste refrigerant to the refrigerant collection pipe  18 , thereby circulating the refrigerant. The refrigerant channel  16  serves to prevent a process performed by the plasma processing apparatus  1  from being affected by the increase in the temperature of the shower head  12  due to the generation of plasma. 
     Since the conventional plasma processing apparatus  1  has the refrigerant channel  16 , which is not formed directly in the shower head  12  but is formed in the upper electrode  10 , so that the shower head  12  is indirectly cooled, it is not easy to control the temperature of the shower head  12 . When the temperature of the shower head  12  is increased due to the difficulty in controlling the temperature of the shower head  12 , high-frequency power transmission efficiency is decreased and affects etch rate or uniformity in etching, thereby deteriorating the reproducibility of plasma treatment. 
     SUMMARY OF THE INVENTION 
     Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a plasma processing device, in which the temperature of a shower head is directly adjusted, thereby improving the reproducibility of plasma treatment. 
     It is another object of the present invention to provide a plasma processing device, which comprises a heat transmission unit installed between a shower head and an upper electrode, thereby easily adjusting the temperature of the shower head. 
     In accordance with one aspect of the present invention, the above and other objects can be accomplished by the provision of a plasma processing apparatus for generating plasma in a chamber maintained in a vacuum state and processing a substrate using the plasma, comprising: upper and lower electrodes respectively provided in upper and lower portions of the chamber for applying high-frequency power into the chamber; a shower head connected to the lower portion of the upper electrode for diffusing a process gas into the chamber; a refrigerant channel passing through the shower head in the horizontal direction for providing a passage for passing a refrigerant; and a refrigerant circulating unit connected to both ends of the refrigerant channel for supplying the refrigerant to one end of the refrigerant channel and collecting the refrigerant from the other end of the refrigerant channel to circulate the refrigerant. 
     In accordance with another aspect of the present invention, there is provided a plasma processing apparatus for generating plasma in a chamber maintained in a vacuum state and processing a substrate using the plasma, comprising: upper and lower electrodes respectively provided in upper and lower portions of the chamber for applying high-frequency power into the chamber; a shower head connected to an edge portion protruded downwardly from the lower surface of the upper electrode for diffusing a process gas into the chamber; a refrigerant channel passing through the upper electrode in the horizontal direction for providing a passage for passing a refrigerant supplied from the outside; a heat transmission unit contacting the upper surface of the shower head and the lower surface of the upper electrode for transmitting the heat of the shower head to the upper electrode; and a refrigerant circulating unit connected to both ends of the refrigerant channel for supplying the refrigerant to one end of the refrigerant channel and collecting the refrigerant from the other end of the refrigerant channel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a sectional view of a conventional plasma processing apparatus; 
         FIG. 2  is a sectional view of a plasma processing apparatus in accordance with a first embodiment of the present invention; 
         FIG. 3  is a perspective view of a shower head of the plasma processing apparatus in accordance with the first embodiment of the present invention; 
         FIG. 4  is a sectional view of a plasma processing apparatus in accordance with a second embodiment of the present invention; 
         FIG. 5  is a perspective view of a heat transmission unit of the plasma processing apparatus in accordance with the second embodiment of the present invention; 
         FIG. 6  is a perspective view of another heat transmission unit of the plasma processing apparatus in accordance with the second embodiment of the present invention; and 
         FIG. 7  is a perspective view of yet another heat transmission unit of the plasma processing apparatus in accordance with the second embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now, preferred embodiments of the present invention will be described in detail with reference to the annexed drawings. 
     First Embodiment 
     As shown in  FIG. 2 , a plasma processing apparatus  100  in accordance with a first embodiment of the present invention comprises an upper electrode  110 , a lower electrode  120 , a shower head  150 , internal elevating pins  130 , external elevating bars  140 , a process gas supply unit (not shown), and an exhaust unit (not shown), which are installed in a chamber maintained in a vacuum state. Here, the structures and functions of the lower electrode  120 , the internal elevating pins  130 , the external elevating bars  140 , the process gas supply unit, and the exhaust unit of the plasma processing apparatus  100  of this embodiment are substantially the same as those of a conventional plasma processing apparatus, and a detailed description thereof will thus be omitted because it is considered to be unnecessary. 
     The structure and functions of the upper electrode  110  and the shower head  150  of the plasma processing apparatus  100  of this embodiment are different from those of the conventional plasma processing apparatus, and a detailed description thereof will be made in detail, as below. 
     Differing from the upper electrode  10  of the conventional plasma processing apparatus  1 , the upper electrode  110  of the plasma processing apparatus  100  of this embodiment does not have a refrigerant channel formed therethrough. Accordingly, the upper electrode  110  has a simple structure and is easily manufactured. 
     The shower head  150  is connected to the lower portion of the upper electrode  110 , and serves to uniformly diffuse a process gas supplied from the outside into the chamber. In this embodiment, a refrigerant channel  152  is uniformly formed in the horizontal direction throughout all regions of the shower head  150 . Since the shower head  150  of the plasma processing apparatus  100  of this embodiment is directly cooled through the refrigerant channel  152 , it is easy to control the temperature of the shower head  150 . In order to form the refrigerant channel  152  directly through the shower head  150 , the shower head  150  has a thickness of approximately 17 mm, while the shower head  12  of the conventional plasma processing apparatus  1  has a thickness of approximately 10 mm. 
     Both ends of the refrigerant channel  152  are connected to a refrigerant circulating unit  160  so that the refrigerant circulating unit  160  supplies a refrigerant to the refrigerant channel  152  and then collects the refrigerant from the refrigerant channel  152  to circulate the refrigerant. In this embodiment, the refrigerant circulating unit  160  comprises a refrigerant supply pipe  162 , a refrigerant collection pipe  164 , and a refrigerant circulating pump  166 . 
     The refrigerant supply pipe  162  passes through the chamber, and is connected one end of the refrigerant channel  152 . The refrigerant supply pipe  162  serves to supply a new refrigerant from the outside to the refrigerant channel  152 . 
     Identically with the refrigerant supply pipe  162 , the refrigerant collection pipe  164  passes through the chamber, and is connected the other end of the refrigerant channel  152 . The refrigerant collection pipe  164  serves to collect the waste refrigerant, having been discharged from the refrigerant channel  152  to the outside. 
     The refrigerant circulating pump  166  is connected to the refrigerant supply pipe  162  and the refrigerant collection pipe  164 , and serves to forcibly circulate the refrigerant. A refrigerant storage tank for storing a designated amount of the refrigerant may be installed in the refrigerant circulating pump  166 . 
     In this embodiment, end caps  168  are used to interconnect the refrigerant circulating pump  166  and the refrigerant supply and recovery pipes  162  and  164 . The end caps  168  facilitate the connection and disconnection of the refrigerant circulating pump  166 , which is prepared separately from the chamber, to and from the refrigerant supply pipe  162  and the refrigerant collection pipe  164 , which are fixed to the chamber. In order to maintain and repair the plasma processing apparatus  100 , the upper wall of the chamber of the plasma processing apparatus  100  is opened. When the upper wall of the chamber is opened, it is necessary to first separate the refrigerant circulating pump  166  from the refrigerant supply pipe  162  and the refrigerant collection pipe  164 . Accordingly, since the refrigerant circulating pump  166  is easily connected to and disconnected from the refrigerant supply pipe  162  and the refrigerant collection pipe  164 , the plasma processing apparatus  100  of this embodiment is advantageous in that its maintenance and repair is easy. 
     In this embodiment, as shown in  FIG. 2 , the refrigerant supply pipe  162  and the refrigerant collection pipe  164  are protruded to the outside through the upper wall of the chamber. This structure also facilitates the maintenance and repair of the plasma processing apparatus  100 . That is, when the refrigerant supply pipe  162  and the refrigerant collection pipe  164  are protruded to the outside through side walls of the chamber, a space occupied by the plasma processing apparatus  100  is enlarged and the refrigerant supply pipe  162  and the refrigerant collection pipe  164  may hinder the maintenance and repair of the plasma processing apparatus  100 . 
     As described above, the shower head  150  of the plasma processing apparatus  100  of this embodiment has a larger thickness than that of the shower head of the conventional plasma processing apparatus. Thereby, the shower head  150  has an increased weight. In order to reduce the weight of the shower head  150 , grooves  154  are formed in the upper surface of the shower head  150 . That is, as shown in  FIG. 3 , the grooves  154 , which are longitudinally extended, are carved in the upper surface of the shower head  150  at positions away from the refrigerant channel  152 . Process gas diffusion holes  156  for diffusing the process gas are formed along the grooves  154  through the shower head  150  in the thickness direction. When the grooves  154  are formed in the shower head  150 , the shower head  150  has a reduced weight, thereby reducing a load applied to the plasma processing apparatus  100 . Further, the process gas diffused through the process gas diffusion holes  156  flows smoothly, thereby being uniformly diffused. 
     Second Embodiment 
     As shown in  FIG. 4 , a plasma processing apparatus  200  in accordance with a second embodiment of the present invention comprises an upper electrode  210 , a lower electrode  220 , a shower head  250 , a heat transmission unit  260 , a refrigerant circuiting unit  270 , internal elevating pins  230 , external elevating bars (not shown), a process gas supply unit (not shown), and an exhaust unit  240 , which are installed in a chamber maintained in a vacuum state. Here, the structures and functions of the upper electrode  210 , the lower electrode  220 , the internal elevating pins  230 , the external elevating bars, the process gas supply unit, and the exhaust unit  240  of the plasma processing apparatus  200  of this embodiment are substantially the same as those of the conventional plasma processing apparatus, and a detailed description thereof will thus be omitted because it is considered to be unnecessary. 
     The structure and functions of the shower head  250 , the heat transmission unit  260 , and the refrigerant circulating unit  270  of the plasma processing apparatus  200  of this embodiment are different from those of the conventional plasma processing apparatus, and a detailed description thereof will be made in detail, as below. 
     The heat transmission unit  260  is provided on the upper surface of the shower head  250  of the plasma processing apparatus  200  of this embodiment. The heat transmission unit  260  serves to transmit the heat of the shower head  250  to the upper electrode  210 . In this embodiment, the heat transmission unit  260  is disposed in a space formed between the upper surface of the shower head  250  and the lower surface of the upper electrode  210  such that the heat transmission unit  260  contacts both the upper surface of the shower head  250  and the lower surface of the upper electrode  210 . Thereby, the heat transmission unit  260  transmits the heat of the shower head  250  to the upper electrode  210 . On the other hand, although a space having a designated height exists between the shower head and the upper electrode in the conventional plasma processing apparatus, the conventional plasma processing apparatus does not comprise a direct contact unit between the shower head and the upper electrode, thus causing a difficulty in directly cooling the shower head. The plasma processing apparatus  200  of this embodiment solves the above problem of the conventional plasma processing apparatus. That is, the upper electrode  210 , which is cooled directly by the refrigerant, contacts the shower head  250  at several portions so that the heat of the shower head  250  is easily transmitted to the upper electrode  210 . 
     Preferably, the heat transmission unit  260  of the plasma processing apparatus  200  of this embodiment is made of a metal having an excellent thermal conductivity. 
     As shown in  FIG. 5 , the heat transmission unit  260  may comprise a plurality of heat transmission pins  262  separated from each other by a designated interval. The heat transmission pins  262  are uniformly disposed throughout all regions of the shower head  250 . 
     Further, as shown in  FIGS. 6 and 7 , the heat transmission unit  260  may comprise a plurality of heat transmission plates  264  or a heat transmission lattice  266 . Preferably, the heat transmission plates  264  or the heat transmission lattice  266  are uniformly disposed throughout all regions of the shower head  250  so as to uniformly adjust the temperature of all regions of the shower head  250 . 
     When the heat transmission unit  260  comprises the heat transmission plates  264  or the heat transmission lattice  266 , holes  268  for passing a process gas are preferably formed through the heat transmission plates  264  or the heat transmission lattice  266 , thereby allowing the process gas to smoothly flow. As shown in  FIGS. 6 and 7 , a plurality of the holes  268  pass through the heat transmission plates  264  or the heat transmission lattice  266  in the thickness direction. 
     A refrigerant channel  212  is formed in the upper electrode  210 . The refrigerant channel  212  passes through the upper electrode  210  in the horizontal direction such that the refrigerant channel  212  is disposed throughout all regions of the upper electrode  210 . 
     Both ends of the refrigerant channel  212  are connected to the refrigerant circulating unit  270  so that the refrigerant circulating unit  270  supplies a refrigerant to the refrigerant channel  212  and then collects the refrigerant from the refrigerant channel  212  to circulate the refrigerant. In this embodiment, the refrigerant circulating unit  270  comprises a refrigerant supply pipe  272 , a refrigerant collection pipe  274 , and a refrigerant circulating pump  276 . 
     The refrigerant supply pipe  272  passes through the wall of the chamber, and is connected to one end of the refrigerant channel  212 . The refrigerant supply pipe  272  serves to supply a new refrigerant from the outside to the refrigerant channel  212 . 
     Identically with the refrigerant supply pipe  272 , the refrigerant collection pipe  274  passes through the wall of the chamber, and is connected the other end of the refrigerant channel  212 . The refrigerant collection pipe  274  serves to collect the waste refrigerant, having being discharged from the refrigerant channel  212  to the outside. 
     The refrigerant circulating pump  276  is connected to the refrigerant supply pipe  272  and the refrigerant collection pipe  274 , and serves to forcibly circulate the refrigerant. A refrigerant storage tank for storing a designated amount of the refrigerant may be installed in the refrigerant circulating pump  276 . 
     In this embodiment, end caps  278  are used to interconnect the refrigerant circulating pump  276  and the refrigerant supply and recovery pipes  272  and  274 . The end caps  278  facilitate the connection and disconnection of the refrigerant circulating pump  276 , which is prepared separately from the chamber, to and from the refrigerant supply pipe  272  and the refrigerant collection pipe  274 , which are fixed to the chamber. In order to maintain and repair the plasma processing apparatus  200 , the upper wall of the chamber of the plasma processing apparatus  200  is opened. When the upper wall of the chamber is opened, it is necessary to first separate the refrigerant circulating pump  276  from the refrigerant supply pipe  272  and the refrigerant collection pipe  274 . Accordingly, since the refrigerant circulating pump  276  is easily connected to and disconnected from the refrigerant supply pipe  272  and the refrigerant collection pipe  274 , the plasma processing apparatus  200  of this embodiment is advantageous in that its maintenance and repair is easy. 
     In this embodiment, as shown in  FIG. 4 , the refrigerant supply pipe  272  and the refrigerant collection pipe  274  are protruded to the outside through the upper wall of the chamber. This structure also facilitates the maintenance and repair of the plasma processing apparatus  200 . That is, when the refrigerant supply pipe  272  and the refrigerant collection pipe  274  are protruded to the outside through side walls of the chamber, a space occupied by the plasma processing apparatus  200  is enlarged and the refrigerant supply pipe  272  and the refrigerant collection pipe  274  may hinder the maintenance and repair of the plasma processing apparatus  200 . 
     As apparent from the above description, the present invention provides a plasma processing apparatus, which has several effects, as below. 
     First, since the plasma processing apparatus of the present invention comprises a refrigerant channel formed in a shower head so that the shower head can be cooled, it is easy to adjust the temperature of the shower head, thereby improving the reproducibility of plasma treatment. 
     Second, the plasma processing apparatus of the present invention comprises a plurality of grooves formed in the upper surface of the shower head, thereby decreasing a burden caused by the increase in the thickness and weight of the shower head due to the formation of the refrigerant channel in the shower head, facilitating the smooth flow of a process gas to increase cooling efficiency, and allowing the distribution of the temperature to be uniformed. 
     Third, the plasma processing apparatus of the present invention further comprises a heat transmission unit formed between the shower head and an upper electrode so that the upper electrode cooled by a refrigerant contacts the shower head, thereby causing the heat of the shower head to be easily transmitted to the upper electrode and easily adjusting the temperature of the shower head. 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.