Patent Publication Number: US-2012031339-A1

Title: Deposition head and film forming apparatus

Description:
TECHNICAL FIELD 
     The present disclosure relates to a deposition head for depositing an organic film, for example, in manufacturing an organic EL device, and relates to a deposition apparatus including the deposition head. 
     BACKGROUND ART 
     Recently, an organic EL device utilizing electroluminescence (EL) has been developed. Since the organic EL device consumes lower power compared with a cathode-ray tube or the like and is self-luminescent, there are some advantages such as a view angle wider than that of a liquid crystal display (LCD). 
     The most basic structure of this organic EL device includes an anode (positive electrode) layer, a light-emitting layer, and a cathode (negative electrode) layer stacked sequentially on a glass substrate to form a sandwiched shape. In order to transmit light from the light-emitting layer, a transparent electrode made of ITO (Indium Tin Oxide) is used for the anode layer on the glass substrate. Such organic EL device is generally manufactured by forming the light-emitting layer and the cathode layer in sequence on the glass substrate having thereon the ITO layer (anode layer) and by additionally forming a sealing film. 
     The organic EL device as described above is generally manufactured by a processing system including various film forming apparatuses or etching apparatuses configured to form a light emitting layer, a cathode layer, a sealing layer, and the like. 
     By way of example, as a general method of forming a light emitting layer, there has been known a method in which a material gas is supplied to a deposition head from a material gas supply source and the material gas is discharged from the deposition head toward a glass substrate so as to be deposited thereon. 
     Patent Document 1 describes a deposition head  20  including a single dispersion plate  41  having multiple through-holes  40  as depicted in  FIG. 2 , and a deposition head  20  including multiple branch flow lines  44  branched from a gas flow line communicating with a material gas inlet port  43  as depicted in  FIG. 3 .
     Patent Document 1: Japanese Patent Laid-open Publication No. 2004-079904   

     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, if an organic film is formed by using a deposition head including a dispersion plate depicted in FIG.  2 , the amount of the material gas passing through through-holes of the dispersion plate may vary depending on a distance from a supply port through which the material gas is supplied into the deposition head. Further, since an equi-thermal property of the material gas is not considered, there is a problem that a temperature of the material gas is not uniformized and a film is not formed on a substrate in a sufficiently uniform manner. 
     A deposition head including branch flow lines therein as depicted in  FIG. 3  is used for a small-sized target substrate corresponding to a small-sized display of about 20 inches. If a film is formed on a large-sized glass substrate used for a large-sized display, of which production has recently been demanded, having a size, for example, about 4.6 times than a conventional one, a deposition head needs to become larger accordingly. When branch flow lines are formed within a large-sized deposition head, the number of the branch flow lines may be increased. Thus, it takes a long time to manufacture the deposition head and manufacturing costs may be increased. Further, if the number of the branch flow lines is increased, a temperature distribution of a material gas passing through the branch flow lines may not become uniformized. Thus, a material gas cooled down to a low temperature can be solidified within the branch flow lines. 
     Accordingly, the present disclosure provides a deposition head capable of discharging a material gas having a uniform flow rate and equi-thermal property from each component in a large-sized substrate as well as a conventional small-sized one and capable of forming a uniform thin film and also provides a deposition apparatus including the deposition head. 
     Means for Solving the Problems 
     In accordance with an aspect of the present disclosure, there is provided a deposition head provided within a deposition apparatus for forming a thin film on a substrate and configured to discharge a material gas toward the substrate. The deposition head may include an outer casing, and an inner casing provided within the outer casing and into which the material gas is introduced. In the inner casing, an opening configured to discharge the material gas toward the substrate may be formed, and a heater configured to heat the material gas may be provided at an outer surface of the outer casing or in a space between the outer casing and the inner casing. 
     Further, the heater may be fixed to a plate member provided between the outer casing and the inner casing, and the heater may be provided along a periphery of a side surface of the outer casing or the inner casing. The heater may include a sheath heater or a cartridge heater, and a spacer member configured to bring an inner surface of the outer casing into partial contact with an outer surface of the inner casing may be provided on at least one of the outer casing and the inner casing. Moreover, a sealed space may be formed between the outer casing and the inner casing. The heater may be provided within the sealed space, and a volatile liquid may be provided in the sealed space. 
     Further, thermal conductivity of the outer casing may be equal to or higher than thermal conductivity of the inner casing. In this deposition head, since the thermal conductivity of the outer casing is high, heat from the heater is rapidly transferred throughout the whole outer casing, and the whole outer casing is uniformly heated. Further, heat is transferred from the outer casing to the inner casing via a spacer member that brings the inner surface of the outer casing into partial contact with the outer surface of the inner casing. As a result, the inner casing is heated. In this case, the spacer member that brings the inner surface of the outer casing into contact with the outer surface of the inner casing may be provided over the whole outer casing or the whole inner casing. Therefore, the heat may be transferred substantially uniformly to the whole inner casing, and the whole inner casing may be uniformly heated. Thus, the material gas introduced into the inner casing may be heated under the substantially same conditions and the material gas may have a uniform temperature within the inner casing. Thus, the material gas with the uniform temperature distribution may be discharged through the opening toward the substrate and a uniform film may be formed. 
     The spacer member may be provided on either or both of the outer casing and the inner casing, and a spacer member provided on the outer casing may be made of a material different from a material of a spacer member provided on the inner casing. The spacer member may include multiple protrusions formed by press molding or a filling material. 
     The press molding may include an emboss processing or a welding processing. A material of the outer casing may include stainless steel or copper. A material of the inner casing may include stainless steel. A thickness of at least a part of the inner casing may be about 3 mm or less. A gas dispersion plate may be provided within the inner casing. The gas dispersion plate may include a mesh-shaped baffle plate or a punching metal plate. 
     A thermal conductive film may be formed on either or both of the inner casing and the outer casing. The thermal conductive film may be formed on at least an outer surface of the inner casing. A discharge plate configured to uniformly discharge the material gas may be provided in the opening. The discharge plate may include a slit configured to discharge the material gas or the discharge plate may include multiple discharge holes configured to discharge the material gas. The discharge plate may be formed of a stainless steel plate, a stainless block, a cooper plate, or a copper block. 
     In accordance with another aspect of the present disclosure, there is provided a deposition apparatus for forming an organic thin film on a substrate. The deposition apparatus may include a processing chamber configured to accommodate therein a substrate; and a deposition head including an opening configured to discharge a material gas toward the substrate within the processing chamber. The deposition head may include a carrier gas supply unit configured to supply a carrier gas that transports the material gas. An inside of the processing chamber may be depressurized. 
     Effect of the Invention 
     In accordance with the present disclosure, there is provided a deposition head capable of discharging a material gas at a uniform flow rate and temperature from each component toward a large-sized substrate as well as a conventional small-sized one while securing equi-thermal property and capable of forming a uniform thin film, and a deposition apparatus including the deposition head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a film forming apparatus  1  performing deposition. 
         FIG. 2  is an explanatory diagram of a deposition head that includes a single dispersion plate  41  having multiple through-holes  40 . 
         FIG. 3  is an explanatory diagram of a deposition head  20  that includes multiple branch flow lines  44  branched from a gas flow line communicating with a material gas inlet port  43 . 
         FIGS. 4A to 4D  are explanatory diagrams of a manufacturing process of an organic EL device (A). 
         FIG. 5  is a schematic explanatory diagram of a deposition apparatus  60 . 
         FIG. 6A  is a perspective view of a deposition head  66  when viewed from a diagonally lower side, and  FIG. 6B  is a bottom view of the deposition head  66 . 
         FIG. 7  is a perspective view of an outer casing  70 . 
         FIG. 8  is a perspective view of an inner casing  71 . 
         FIGS. 9A and 9B  are explanatory diagrams showing that a heater  77  is provided. 
         FIG. 10  is a schematic cross-sectional view of a deposition head  66   a  in which a heater  77  is provided in accordance with another embodiment of the present disclosure. 
         FIGS. 11A and 11B  are side views of a deposition head  66  to show a shape of a heater  77  provided therein. 
         FIG. 12  is a schematic cross-sectional view of a deposition head  66   b  in which a heater  77  is provided in accordance with a second another embodiment of the present disclosure. 
         FIG. 13A  is a schematic view of a deposition head  66  including a discharge plate  95   a  having a slit  96 .  FIG. 13B  is a schematic view of the deposition head  66  including the discharge plate  95   a  having discharge holes  97 . 
         FIG. 14A  is a schematic front view of a deposition head  66  having a sealed space.  FIG. 14B  is a schematic side view of the deposition head  66  having the sealed space. 
         FIGS. 15A and 15B  show a result of an experimental example. 
         FIGS. 16A to 16C  are graphs showing a result of an experimental example 2. 
     
    
    
     EXPLANATION OF CODES 
       1 : Film forming apparatus
       10 : Chamber     11 : Substrate holding room     12 ,  54 : Holding tables     13 : Vacuum pump     14 : Exhaust port     20 ,  66 ,  66   a,    66   b:  Deposition heads     30 : Material supply unit     40 : Through-holes     41 : Dispersion plate     43 : Material gas inlet port     44 : Branch flow line     50 : Anode layer     51 : Light emitting layer     52 : Cathode layer     53 : Sealing film layer     60 : Deposition apparatus     61 : Processing chamber     62 : Gate valve     63 : Exhaust line     65 : Rail     67 : Material supply source     68 : Material supply line     70 : Outer casing (first casing)     71 : Inner casing (second casing)     72 ,  73 : Opening surfaces     77 ,  78 : Heaters     80 : Groove     81 : Heater bloc     82 : Material gas inlet port     83 : Baffle plate     85 : Protrusion     90 : Plate member     95 : Discharge plate     96 : Slit     97 : Discharge holes     100 : Sealed space   G: Substrate   L: Liquid   
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the specification and the drawings, elements having substantially the same function are assigned same reference numerals and redundant description thereof may be omitted. 
       FIG. 1  is a schematic view of a film forming apparatus  1  performing deposition. As depicted in  FIG. 1 , the film forming apparatus  1  may include a chamber  10 , a substrate holding chamber  11  provided under the chamber  10 , and a deposition head  20  extended over the chamber  10  and the substrate holding chamber  11 . The deposition head  20  may be positioned such that its opening  21  configured to discharge a material gas within the substrate holding chamber  11  faces downwards. Further, a holding table  12  configured to horizontally hold a substrate G may be provided within the substrate holding chamber  11 , and the substrate G is mounted on the holding table  12  such that the substrate G&#39;s upper surface on which a film is formed faces upwards (face-up state). Thus, the opening  21  of the deposition head  20  may be positioned so as to face the upper surface of the substrate G. 
     The chamber  10  may include an exhaust port  14  through which exhaustion is performed by a vacuum pump  13 . During a film formation, the insides of the chamber  10  and the substrate holding chamber  11  may be in a vacuum state. The deposition head  20  may communicate, via a material supply line  31 , with a material supply unit  30  provided outside the chamber  10 . Further, a valve  32  configured to control a supply of a material gas may be provided in the material gas supply line  31 . The material supply line  31  may be connected to a gas retreat line  33  communicating with the vacuum pump  13  and retreating a gas when the valve  32  is closed. Further, a valve  34  may be provided in the gas retreat line  33 . The deposition head  20  may be connected to a gas outlet line  35  communicating with the vacuum pump  13  and collecting a remaining material gas within the deposition head  20  after the film formation. Further, a valve  36  may be provided in the gas outlet line  35 . 
     In the deposition head  20  provided within the film forming apparatus  1  configured as described above, in order to form a uniform thin film on the substrate G, it may be required to discharge the material gas supplied from the material supply unit  30  toward the substrate G through the opening  21  at a flow rate as uniform as possible and with a secured equi-thermal property. 
       FIGS. 4A to 4D  are explanatory diagrams of a manufacturing process of an organic EL device (A) manufactured by various film forming apparatuses including a deposition apparatus  60  using a deposition head  66  in accordance with an embodiment of the present embodiment. As depicted in FIG.  4 Aa, the substrate G on which an anode (positive) layer  50  is formed may be provided. The substrate G may be made of a transparent material such as glass. The anode layer  50  may be made of a transparent conductive material such as ITO (Indium Tin Oxide). Further, the anode layer  50  may be formed on an upper surface of the substrate G by means of, for example, sputtering. 
     Above all, as depicted in  FIG. 4A , a light emitting layer (organic layer)  51  may be formed on the anode layer  50  by means of deposition. The light emitting layer  51  may be configured as a multi-layered structure in which, for example, a hole transport layer, a non-light-emitting layer (electron blocking layer), a blue light emitting layer, a red light emitting layer, a green light emitting layer, and an electron transport layer are layered. 
     Then, as depicted in  FIG. 4B , a cathode (negative) layer  52  made of, for example, Ag and Al may be formed on the light emitting layer  51  by means of, for example, sputtering using a mask. 
     Subsequently, as depicted in  FIG. 4C , for example, the light emitting layer  51  may be dry-etched by using the cathode layer  52  as a mask, so that the light emitting layer  51  may be patterned. 
     Thereafter, as depicted in  FIG. 4D , a sealing film layer  53  made of an insulating material such as silicon nitride (SiN) may be formed so as to cover the light emitting layer  51 , the cathode layer  52 , and an exposed region of the anode layer  50 . The sealing film layer  53  may be formed by means of, for example, microwave plasma CVD. 
     In the organic EL device A manufactured as described above, the light emitting layer  51  may emit light by applying a voltage between the anode layer  50  and the cathode layer  52 . This organic EL device A can be used for a display device or a surface light emitting device (illumination/light source) and can be used for other electronic devices. 
     Then, the deposition apparatus  60  for forming the light emitting layer  51  depicted in  FIG. 4A  will be explained with reference to the drawings. Further, since film forming processes such as sputtering, etching and plasma CVD other than the film forming process depicted in  FIG. 4A  may be performed by typical apparatuses and methods, detailed explanation thereof will be omitted. 
       FIG. 5  is a schematic explanatory diagram of a deposition apparatus  60  in accordance with an embodiment of the present disclosure. The deposition apparatus  60  depicted in  FIG. 5  may form an organic film including the light emitting layer  51  depicted in  FIG. 4A  by means of deposition. 
     The deposition apparatus  60  may include a sealed processing chamber  61 . The sealed processing chamber  61  may have a rectangular shape of which a longitudinal direction corresponds to a transfer direction of the substrate G. Front and rear surfaces of the processing chamber  61  may be connected to another film forming apparatus or the like via gate valves  62 . 
     A bottom surface of the processing chamber  61  may be connected to an exhaust line  63  including a vacuum pump (not illustrated), so that the inside of the processing chamber  61  may be depressurized. Further, the processing chamber  61  may include therein a holding table  64  configured to horizontally hold the substrate G. The substrate G may be mounted on the holding table  64  in a face-up state in which the substrate G&#39;s upper surface on which the anode layer  50  is formed faces upwards. The holding table  64  may be configured to move on a rail  65  provided along the transfer direction of the substrate G so as to transfer the substrate G. 
     On a ceiling surface of the processing chamber  61 , multiple deposition heads  66  (for example, six in  FIG. 5 ) may be provided along the transfer direction of the substrate G. Each of the deposition heads  66  may be connected, via each of material supply lines  68 , to each of multiple material supply sources  67 , respectively. Each of the material supply lines  68  may be configured to supply vapor (material gas) of a film forming material for forming the light emitting layer  51 . While the vapor of the film forming material supplied from the material supply sources  67  are discharged through each of the deposition heads  66 , the substrate G held on the holding table  64  may be transferred. Thus, a hole transport layer, a non-light-emitting layer, a blue light emitting layer, a red light emitting layer, a green light emitting layer, and an electron transport layer may be stacked in sequence on the upper surface of the substrate G, and the light emitting layer  51  may be formed on the upper surface of the substrate G. 
       FIGS. 6A and 6B  are schematic explanatory diagrams of the deposition head  66 .  FIG. 6A  is a perspective view of the deposition head  66  when viewed from a diagonally lower side, and  FIG. 6B  is a bottom view of the deposition head  66 .  FIG. 7  is a perspective view of an outer casing  70 , and  FIG. 8  is a perspective view of an inner casing  71 . Although the multiple deposition heads  66  are depicted in  FIG. 5 , each deposition head  66  may have the same configuration. Further, as described above in detail, within the processing chamber  61 , a lower surface of the deposition head  66  may face the upper surface of the substrate G horizontally held on the holding table  64  in the face-up state. Hereinafter, in the present specification, the outer casing  70  will be referred to as a first casing  70  and the inner casing  71  will be referred to as a second casing  71 . 
     The first casing  70  and the second casing  71  may have a rectangular shape. The first casing  70  may be slightly larger than the second casing  71 . Further, the deposition head  66  may be configured to include the first casing  70  inserting the second casing  71  therein. Openings  72  and  73  may be formed on a lower surface of the first casing  70  and a lower surface of the second casing  71 , respectively. The second casing  71  may be inserted into the lower opening  72  of the first casing  70 , so that both openings  72  and  73  may be overlapped with each other. 
     The first casing  70  may be made of a material having higher thermal conductivity than the second casing  71 . For example, copper may used for the first casing  70 . An upper surface (a surface facing the opening  72 ) of the first casing  70  may be connected to the material supply line  68  communicating with the material supply source  67  depicted in  FIG. 5 . 
     Between side surfaces  75  and  76  of the first casing  70 , the side surface  75  is larger than the side surface  76 . The side surface  75  may include a groove  80  in which a heater  77  is embedded. The heater  77  may be provided along a periphery of the square-shaped side surface  75 . Since the heater  77  is embedded in the groove  80 , a contact surface between the side surface  75  of the first casing  70  and the heater  77  may increase, resulting in an increase of thermal conductivity. 
     In the drawing, the groove  80  may extend to a side surface of the material supply line  68  connected to the upper surface of the first casing  70 , and the heater  77  may be embedded therein. 
     In order to embed the heater  77  in the groove  80 , as depicted in  FIG. 9A , the heater  77  may be just put in the groove  80 . Further, as depicted in  FIG. 9B , the heater  77  may be put in the groove  80 , and then, be pressed down from an upper direction of the groove  80 . As a result, the side surface  75  of the first casing  70  can be securely in contact with the heater  77  and a contact surface therebetween may increase, resulting in increasing thermal conductivity. 
     Between the side surfaces  75  and  76  of the first casing  70 , the side surface  76  is smaller than the side surface  75 . The side surface  76  may have thereon a heater block  81  including therein a heater  78 . The heater block  81  may be made of a material having high thermal conductivity such as copper. A surface of the heater block  81  may be contacted with the side surface  76  of the first casing  70 . Thus, heat transferred from the heater  78  to the heater block  81  may be rapidly transferred to the entire side surface  76  of the first casing  70 . 
     The inner casing  71  may be made of a material having less thermal conductivity than the first casing  70 . For example, stainless steel may be used for the inner casing  71 . In an upper surface (a surface facing the opening  73 ) of the inner casing  71 , a material gas inlet port  82  through which a material gas is introduced from the material supply line  68  may be formed. 
     As depicted in  FIGS. 6A and 6B , within the second casing  71 , a baffle plate  83  serving as a gas dispersion plate may be provided so as to partition the opening  73  from the material gas inlet port  82 . The baffle plate  83  may be spaced away from the opening  73  and arranged so as to be in parallel with the opening  73  within the second casing  71 . The baffle plate  83  may have, for example, a mesh shape, and multiple holes  84  may be formed in the entire surface of the baffle plate  83 . The baffle plate  83  provided within the second casing  71  may be one or more, and may be provided at a certain position within the second casing  71 . The number and the arrangement of the baffle plate  83  may be appropriately changed depending on a flow velocity or a flow rate of a material gas in order that the material gas can be diffused uniformly within the second casing  71 . The baffle plate  83  may have a shape suitable for diffusing the material gas and may have, for example, a punching metal shape other than the mesh shape. 
     As depicted in  FIG. 8 , multiple protrusions  85  serving as spacer members may be formed over the second casing  71 . These multiple protrusions  85  may be formed by means of press molding such as an emboss processing, and a height of each protrusion  85  may be substantially uniform. The multiple protrusions  85  may be provided uniformly in the entire outer surfaces of the second casing  71 . As described above, since the second casing  71  is inserted into the first casing  70 , the inner surfaces of the first casing  70  and the outer surfaces of the second casing  71  may be in partial contact with each other at positions of the multiple protrusions  85 . Further, in the deposition head  66  in accordance with the present embodiment, as depicted in  FIG. 8 , the protrusions  85  serving as the spacer members may be formed in the second casing  71 . However, if it is verified that thermal conduction from the first casing  70  to the second casing  71  is rapidly performed without providing the spacer members (protrusions  85 ), the spacer members (protrusions  85 ) need not be provided in the second casing  71 . 
     Within the processing chamber  61  of the deposition apparatus  60  including the deposition head  66  depicted in  FIG. 5  as described above, the substrate G having the anode layer formed on its upper surface, i.e., in the face-up state may be mounted on the holding table  64  as depicted in  FIG. 5 , and may be transferred along the rail  65 . A vapor of a film forming material (material gas) may be introduced into the second casing  71  from the material supply source  67  through the material supply line  68 . Then, the material gas introduced into the second casing  71  through the material gas inlet port  82  depicted in  FIG. 6  may be diffused while passing through the baffle plate  83 . Then, the material gas may be uniformly discharged from the lower surfaces (opening and  73 ) of the deposition head  66  toward the upper surface of the substrate G. 
     In the deposition head  66  depicted in  FIGS. 6A and 6B , the first casing  70  may be heated by the heaters  77  and  78  such as a sheath heater or a cartridge heater. In this case, since the first casing  70  may be made of a material having high thermal conductivity, heat may be rapidly transferred from the heaters  77  and  78  to the entire of the first casing  70 . Thus, the entire of the first casing  70  may be heated uniformly. Via the multiple protrusions  85  that bring the inner surfaces of the first casing  70  in partial contact with the outer surfaces of the second casing  71 , heat may be transferred from the first casing  70  to the second casing  71 , so that the second casing  71  may be heated. In this case, since the multiple protrusions  85  that bring the inner surfaces of the first casing  70  in contact with the outer surfaces of the second casing  71  may be provided in the whole second casing  71 , heat may be transferred substantially uniformly to the entire of the second casing  71 . Thus, the second casing  71  may be heated uniformly. Accordingly, the material gas introduced into the second casing  71  may be heated within the second casing  71  under the same conditions, and a temperature of the material gas within the second casing  71  may be uniformized. Thus, the material gas having the uniform temperature may be discharged from the lower surface (openings  72  and  73 ) of the deposition head  66  toward the upper surface of the substrate G as depicted in  FIG. 5 . 
     That is, in the deposition head  66  in accordance with the present embodiment, as depicted in  FIGS. 4A to 4D , the gas may be uniformly (equi-thermally) discharged toward the substrate G in consideration of both the flow rate and the temperature of the gas. As a result, an organic thin film (light emitting layer  51 ) having high uniformity may be formed on the substrate G. Further, as compared with the conventional deposition head including therein branch flow lines, in accordance with the deposition head  66  of the present embodiment, an equi-thermal property can be secured, and solidification of the material gas at a low temperature region can be prevented. 
     If the material gas is discharged to a large-sized substrate used for a large-sized display, which is recently in high demand, a metal plate structure formed by cutting steel may be provided. In this case, as compared with the conventional deposition head including therein branch flow lines, it may be possible to greatly reduce manufacturing costs for the deposition head  66  in accordance with the present embodiment. Conventionally, a sheet-shaped heater (mica heater) of high cost has been used for a deposition head that discharges a material gas onto a small-sized substrate for a small-sized display. However, if the sheet-shaped heater is used for a large-sized deposition head for a large-sized substrate costs may be increased due to the large size. Therefore, by using pipe-shaped heaters  77  and such as the sheath heater or the cartridge heater described in the present embodiment together with the sheet-shaped heater, it may be possible to reduce cost, and also possible to secure an equi-thermal property within the deposition head. 
     There has been described the embodiment of the present disclosure, but the present disclosure is not limited to the above-described embodiment. It would be understood by those skilled in the art that various changes and modifications may be made within the scope of the accompanying claims and it shall be understood that all changes and modifications are included in the scope of the present disclosure. 
     By way of example, in the above-described embodiment, the deposition apparatus  60  for manufacturing the organic EL device A has been explained. Further, the present disclosure can be also applied to a case where a film is formed by means of deposition such as Li deposition in processes of various electronic devices. Although it has been described that the substrate G as a target object is a glass substrate, the glass substrate may include a silicon substrate, a square substrate, a circular substrate or the like. Further, the present disclosure can be applied to a target object other than a substrate. 
     In the present embodiment, it has been described that the heaters  77  (groove  80 ) and  78  (heater block  81 ) are provided in both side surfaces  75  and  76  of the deposition head  66 . However, the present disclosure is not limited thereto, and the heaters  77  and  78  may be provided in only one of the side surfaces  75  and  76 . That is, one of the heaters  77  and  78  provided in the side surfaces  75  and  76  may be omitted. Desirably, a shape, the number, and an arrangement of the heaters  77  and  78  may be changed appropriately depending on a deposition head  66 &#39;s temperature measured while being heated. The arrangement thereof is not limited to an example shown in  FIG. 6 . 
     By way of example,  FIG. 10  is a schematic cross-sectional view of a deposition head  66   a  having a heater  77  in a different manner in accordance with another embodiment of the present disclosure. As depicted in  FIG. 10 , in the deposition head  66   a,  the heater  77  may be provided in a space between the first casing  70  and the second casing  71  with a plate member  90  therebetween. The first casing  70  and the second casing  71  may not be directly contacted with each other. Desirably, the heater  77  may not be fixed to the second casing  71 . Further, the heater  77  may be partially fixed to the first casing  70  such that heat leakage may become reduced. Further, the heater  77  may be fixed to another member replacing the above-described plate member  90 , and may be provided between the second casing  71  and the first casing  70 . Thus, an equi-thermal property within the deposition head  66  can be secured with more efficiency.  FIG. 10  shows that lower ends (peripheries of openings  72  and  73  in  FIG. 10 ) of the first casing  70  and the second casing  71  are not in contact with each other. However, the present disclosure is not limited thereto, and the first casing  70  and the second casing  71  may be in contact with each other at the peripheries of the openings  72  and  73 . Further, the heater  77  (plate member  90 ) may be provided airtightly between the first casing  70  and the second casing  71 . 
     In the deposition head  66  in accordance with the above-described embodiment, as depicted in  FIGS. 6A and 6B , the groove  80  may have a circular ring shape in the side surface  75 , and the heater  77  may be put in the groove  80 . However, a shape of the heater  77  is not limited to the circular ring shape.  FIGS. 11A and 11B  are side views of a deposition head  66  to show a shape of a heater  77  provided therein. A shape of the heater  77  can be changed appropriately. As depicted in  FIG. 11A , the heater  77  can be provided on the side surface  75  in a shape of heating both an outer periphery portion and a central portion of the side surface  75 . By providing the heater  77  in the central portion in addition to the periphery portion of the side surface  75  as shown in  FIG. 11A , a temperature at an outer periphery portion and a central portion of the deposition head  66  can be substantially uniformized and a temperature difference on a cross section within the deposition head  66  can be decreased. Therefore, an equi-thermal property of a material gas within the deposition head  66  can be secured with high accuracy. 
     If an equi-thermal property is sufficiently secured in the side surface  75 , even if arrangement density of the heater  77  is reduced, the equi-thermal property within the deposition head  66  can be sufficiently secured. Therefore, as depicted in  FIG. 11B , the arrangement density of the heater  77  can be reduced as compared with the example depicted in  FIG. 11A . The arrangement density of the heater  77  can be changed appropriately depending on a temperature difference on the cross section within the deposition head  66 . Since the inside of the deposition head  66  is in a vacuum state, heat transfer may hardly occur in its central portion as compared with its outer periphery portion. Therefore, it may be desirable to arrange a heater based on a heat transfer condition such that the outer periphery portion, rather than the central portion, can be further heated and thermally uniformized by the heater  77 . 
     The arrangement shape of the heater  77  depicted in  FIG. 11  may not limited to the example where the heater  77  is provided in the side surface  75  of the deposition head  66 , i.e. the outer surface of the outer casing  70 . By way of example, it can be applied to the heater  77  provided in the deposition head  66   a  in accordance with another embodiment of the present disclosure as depicted in  FIG. 10 . 
     In the deposition head  66  in accordance with the above-described embodiment, the first casing  70  may be made of copper; the second casing  71  may be made of stainless steel; and the heater  77  may be provided in the outer surface of the first casing  70 . However, the present disclosure is not limited thereto. The heater  77  does not need to be provided in the outer surface of the first casing  70  in order to secure the equi-thermal property within the deposition head  66 . Therefore, hereinafter, there will be explained, as a second another embodiment of the present disclosure, an example where an arrangement of the heater  77  and a material of each casing are different from the above-described embodiment. 
     By way of example, in the second another embodiment of the present disclosure, the first casing  70  and the second casing  71  may be made of stainless steel, and only the second casing  71  may be coated with a thermal conductive film such as a copper coating having a thickness of about 30 microns or more. In this case, desirably, the heater  77  may be provided between the first casing  70  and the second casing  71  differently from the above-described embodiment. Further, in addition to the second casing  71 , if required, the first casing  70  may be coated appropriately with the thermal conductive film in order to reduce non-uniformity in temperatures on a cross section within a deposition head  66 . That is, whether either or both of the first casing  70  and the second casing  71  is coated with the thermal conductive film may be determined appropriately depending on temperature differences on the cross section within the deposition head  66 . Further, it may be allowed to coat only one side of each casing with the thermal conductive film. However, typically, in case of a copper coating, for example, since a stainless steel plate is immersed in a copper coating tank, the copper coating may be generally performed on both sides of the stainless steel plate. 
       FIG. 12  is a schematic cross-sectional view of a deposition head  66   b  in which only the second casing  71  is coated with the thermal conductive film such as the cooper coating.  FIG. 12  does not show the thermal conductive film. In the deposition head  66   b  depicted in  FIG. 12 , the outer surface of the second casing  71  may be coated with the thermal conductive film. Further, the heater  77  may be provided on the outer surface of the second casing  71  in a space between the first casing  70  and the second casing  71 , which are not in contact with each other. Since the outer surface of the second casing  71  is coated with the thermal conductive film, even if the heater  77  is not provided in the entire outer surface of the second casing  71 , the deposition head  66   b  can be sufficiently heated and thermally uniformized. For this reason, in view of costs, the heater  77  provided on the outer surface of the second casing  71  can be arranged in a low density as depicted in  FIG. 11B . 
     As described above, since each casing (particularly, the second casing  71 ) made of stainless steel is coated with a thermal conductive film such as a copper coating, it may be possible to secure hardness of the casing against thermal deformation. Further, thermal conductivity may be increased, and, thus, it may be possible to suppress non-uniformity in temperature in each component within the deposition head  66 . Since thermal conductivity of each casing (particularly, the second casing  71 ) is increased, the number of the heaters  77  can be reduced as depicted in  FIG. 11B . Thus, the deposition head  66  may be cost effective. In this case, whether either or both of the first casing  70  and the second casing  71  is coated with a copper coating may be determined appropriately depending on a temperature distribution measured in the deposition head  66 . 
     That is, since the first casing  70  and the second casing  71  are made of stainless steel, costs can be greatly reduced, and hardness can be increased as compared with a case where a casing is made of copper. Further, since the stainless steel may be coated with the thermal conductive film, an equi-thermal property within the deposition head  66  can be secured. Further, it may be possible to avoid deformation caused by the copper heat, which may be generated in a case where a casing is made of a copper plate having high thermal conductivity. Herein, the copper coating has been described as the thermal conductive film for increasing thermal conductivity of the stainless steel. However, the thermal conductive film may not be limited to the copper coating. Instead, a film having a higher thermal conductivity than a basic material (material of a casing) can be employed. By way of example, it may be possible to conduct a coating capable of increasing thermal conductivity such as a gold coating and a silver coating. Further, a thermal conductive film may be formed by a junction process of the foil such as a gold/silver foil, or a blast process or a diffusion junction process. However, it may be desirable to conduct a copper coating in view of costs. 
     In the deposition head  66  in accordance with the above-described embodiment, the opening  72  ( 73 ) may be formed by opening one of the side surfaces of the rectangular casing. The material gas within the deposition head  66  may be dispersed by the gas dispersion plate (baffle plate  83 ) provided in the deposition head  66  and discharged to the substrate G through the opening  72  ( 73 ). However, the material gas within the deposition head  66  cannot be dispersed sufficiently by only the gas dispersion plate. Therefore, the material gas may not be discharged uniformly to the substrate G through the opening  72  ( 73 ), and a film may not be formed uniformly. In this case, desirably, an discharge plate formed of, for example, a copper plate and configured to allow the material gas to be discharged uniformly through the opening  72  ( 73 ) may be provide in the deposition head  66  described in the above-described embodiment. 
       FIGS. 13A and 13B  are schematic views of a deposition head  66  including a discharge plate  95  ( 95   a  and  95   b ).  FIG. 13A  is a schematic view of the deposition head  66  including the discharge plate  95   a  having a slit  96 , and  FIG. 13B  is a schematic view of the deposition head  66  including the discharge plate  95   b  having discharge holes  97 . An opening width of the slit  96  may be, for example, about 1 mm. In order to uniformly discharge the material gas from the deposition head  66 , it is desirable that a multiple number of discharge holes  97  may be provided. An arrangement or the number of the discharge holes  97  may be determined in a way that allows the material gas to be uniformly discharged. Since the discharge plate  95  ( 95   a  and  95   b ) depicted in  FIGS. 13A and 13B  is provided in the opening  72  ( 73 ) of the deposition head  66 , it may be possible to more uniformly discharge the material gas to the substrate G, so that a thin film of high uniformity can be formed. However, in the discharge plate  95   a  having the slit  96 , there is a concern that the width of the slit  96  may be changed due to heat generated by temperature increase, and a distribution of the material gas may not be uniformized. Particularly, when a material gas of high temperature is used, it may be desirable to use the discharge plate  95   b  having the discharge holes  97 . By way of example, a diameter of the discharge hole  97  may have a range of from about 1.5 mm to about 3.5 mm, and a pitch between the discharge holes  97  may be about 5 mm. Further, the discharge holes  97  are not limited to be arranged in a single line depicted in  FIG. 13B , and can be arranged in two or more lines. 
     In the above-described embodiment, as depicted in  FIG. 6 , it has been described that heaters such as the sheath heater and the cartridge heater serving as the heaters  77  and  78  may be put in the groove  80  formed in the outer surface of the first casing  70 . In its modification example (another embodiment), as depicted in  FIG. 10 , it has been described that the heater  77  may be provided in the space between the first casing  70  and the second casing  71  with the plate member  90  therebetween. However, a heater provided in the deposition head  66  is not limited to the above configuration. By way of example, a sealed space  100  may be formed between the first casing  70  and the second casing  71 . A volatile liquid L and the pipe-shaped heater  77  whose temperature can be controlled may be provided in the sealed space  100 . 
     Hereinafter, as a third another embodiment of the present disclosure, there will be explained a deposition head  66  having the sealed space  100 , with reference to the accompanying drawings.  FIGS. 14A and 14B  provide a schematic front view ( FIG. 14A ) and a schematic side view ( FIG. 14B ) of a deposition head  66  having the sealed space  100 . In order to explain the inside of the sealed space  100 , a cross section of a part of the sealed space  100  is illustrated. In the sealed space  100 , the heater  77  and the liquid L may be sealed. The liquid L may include, for example, water or naphthalene, which can be evaporated at a certain temperature. The heater  77  may include, for example, a cartridge heater and a sheath heater. 
     As depicted in  FIGS. 14A and 14B , the sealed space  100  may be formed in the entire surface (both side surfaces and  76  of the above-described embodiments) of a deposition head  66  except the opening  72  (lower surface of the deposition head  66  in  FIGS. 14A and 14B ). As depicted in  FIGS. 14A and 14B , on the side surface  75  (larger than the side surface  76 ), three sealed spaces  100  may be formed so as to respectively correspond to three divided portions of the side surface  75  in a longitudinal direction. On the side surface  76 , a single sealed space  100  may be formed so as to cover the entire surface thereof. Further, the sealed space  100  may be formed so as to cover the outer surface of the material supply line  68  configured to supply the material gas. 
     The inside of the sealed space  100  may be in a sealed state, and the liquid L and the heater  77  may be provided therein. The amount of the liquid L may not be sufficient enough to fill the entire inside of the sealed space  100 , but may be sufficient to exist at a bottom portion of the sealed space  100 . In the present embodiment, the heater  77  may be immersed in the liquid L existing within the sealed space  100 . Further, the heater  77  may have a sufficient size/length to heat the liquid L existing at a bottom portion of the sealed space  100 . The size/length thereof can be determined appropriately. 
     In the sealed space  100 , the liquid L existing within the sealed space  100  may be evaporated by being heated by the heater  77 . Evaporated steam may contact with the entire inner surface of the sealed space  100 , so that the sealed space  100  can be heated over all. That is, the sealed space  100  may have a configuration/operation similar to a so-called “heat pipe”. In this case, the liquid L&#39;s steam may be cooled by means of heat exchange with the inner surface after contacting with the inner surface of the sealed space  100 , and liquefied (liquid L) so as to exist within the sealed space  100 . That is, the liquid L may circulate within the sealed space  100  while repeating evaporation and liquefaction. Further, in the present embodiment, a shape of the inner surface of the sealed space  100  is not limited, and may be a typical plane. However, in order to reflux the liquefied liquid L upon contacting with the inner surface of the sealed space  100 , into the liquid L existing at the bottom portion of the sealed space  100  with more efficiency, desirably, the inner surface of the sealed space  100  may have a large surface area and a shape which may easily cause a capillary phenomenon. By way of example, the surface process may be performed on the inner surface of the sealed space  100  to have a mesh shape or a groove shape. 
     In the above-described deposition head  66  around which the sealed space  100  is formed, when a material gas is supplied, the liquid L within the sealed space  100  may be heated by the heater  77  so as to be vaporized. Therefore, the sealed space  100  may be filled with the vapor having an approximately constant temperature. Thus, the deposition head  66 &#39;s side surface entirely covered by the sealed spaces  100  may be uniformly heated by the respective sealed spaces at a certain temperature. Therefore, the material gas supplied from the material supply line  68  may be uniformly heated within the deposition head  66  at a certain temperature. Since the sealed spaces  100  are provided in the entire side surface of the deposition head  66 , the side surface can be uniformly heated with high accuracy. Further, the material gas within the deposition head  66  can be uniformly heated by radiant heat with high accuracy from the uniformly thermalized side surfaces of the deposition head  66 . 
     Since a temperature of the heater  77  provided in each sealed space  100  can be controlled, an internal temperature of each sealed space  100  can be controlled. The internal temperature of each sealed space  100  can be controlled appropriately based on a measured temperature distribution within the deposition head  66 , and the deposition head  66  can be uniformly heated to become a certain temperature with high accuracy. That is, even if a part of the deposition head  66  may have a temperature lower than other portions thereof, by appropriately controlling a temperature of each sealed space  100  corresponding to the low-temperature portion, the whole inside of the deposition head  66  can be quickly and uniformly heated. 
     It has been explained that in the present embodiment (third another embodiment), the side surface  75  of the deposition head  66  may be divided into three portions in a longitudinal direction, and the three sealed spaces  100  respectively corresponding thereto may be formed. The present disclosure is not limited to this embodiment. The number or positions of the sealed spaces  100  formed in the side surface of the deposition head  66  can be appropriately changed so as to efficiently and uniformly heat the inside of the deposition head  66 . 
     In the above-described embodiment, the deposition head  66  may include the first casing  70  and the second casing  71 . The deposition head  66  of the present disclosure is not limited thereto. In the present disclosure, the deposition head  66  need not have a casing. By way of example, a plate-shaped member in a casing shape may be provided. 
     In the above-described embodiment, the multiple protrusions  85  serving as the spacer members configured to bring the inner surface of the first casing  70  into partial contact with the outer surface of the second casing  71  may be formed in the entire outer surface of the second casing  71 . However, the present disclosure is not limited thereto. The protrusions  85  may be formed on the inner surface of the first casing  70 , or the protrusions  85  may be formed on the inner surface of the first casing  70  and the outer surface of the second casing  71 . Here, the material of the protrusions  85  formed on the inner surface of the first casing  70  is different from that on the outer surface of the second casing  71 . Further, as the spacer member, a filling material such as steel wool may be used. 
     EXPERIMENTAL EXAMPLE 
     As an experimental example 1 of the present disclosure, a deposition head having a configuration depicted in  FIG. 6  is actually provided in a deposition apparatus. An outer casing is made of copper; an inner casing is made of stainless steel; and an emboss processing is uniformly performed on the inner casing. Further, a pipe-shaped heater is actually provided at each position depicted in  FIG. 6 . Then, the deposition head is heated by each heater and a material gas is discharged from an opening. At this time, a surface temperature of the deposition head and temperature around the opening are analyzed (simulated). FIGS.  15 Aa and  15 B show a result of the analysis. To be specific,  FIG. 15A  shows the surface temperature of the deposition head, and  FIG. 15B  shows a result of the temperatures measured around the opening of the deposition head. 
     A temperature difference between a central portion of an outer wall and a periphery portion of the outer wall in  FIG. 15A , and a temperature difference between the center portion of the opening and an end portion of the opening in  FIG. 15B  are about 1° C. or less, respectively. As a result, it can be assumed that the surface temperature of the deposition head and the temperatures around the opening of the deposition head have an equi-thermal property secured with high accuracy. 
     As an experimental example 2 of the present disclosure, there is measured a temperature distribution on a cross section within a deposition head while varying an arrangement of a heater and changing presence/absence of a copper coating as a thermal conductive film.  FIGS. 16A to 16C  are graphs showing measurement positions and temperature distributions in this deposition head.  FIGS. 15A and 15B  show measurement data with a longitudinal axis thereof denoting a temperature (° C.) and a horizontal axis thereof denoting a distance (mm) from the center of the deposition head in a width direction. However, all the measurements shown in  FIGS. 16A to 16C  are carried out for a deposition head in which a heater is provided in an outer surface of an inner casing. 
       FIG. 16A  is a graph showing a result of a temperature difference measured on a cross section within a deposition head when a heater density is high as depicted in  FIG. 11A . Meanwhile,  FIG. 16B  is a graph showing a result of a temperature difference measured on a cross section within a deposition head when a heater density is low as depicted in  FIG. 11B .  FIG. 16C  is a graph showing a result of a temperature difference measured on a cross section within a deposition head in which an outer surface of an inner casing is covered with a copper coating when a heater density is low as depicted in  FIG. 11B . 
     As depicted in  FIG. 16A , when the heater density is high, the temperature difference on the cross section within the deposition head may be about ±35° C. at most with respect to a desired internal temperature of about 450° C. Further, as depicted in  FIG. 16B , when the heater density is low, the temperature difference on the cross section within the deposition head may be about ±20° C. at most with respect to a desired internal temperature of about 450° C. Meanwhile, as depicted in  FIG. 16C , if a surface having a heater is covered with the copper coating when the heater density is low, the temperature difference on the cross section within the deposition head may be about ±4.5° C. at most with respect to a desired internal temperature of about 450° C. 
     It can be seen from the result of the experimental example 2 that when the heater density is suppressed to be low and the surface having the heater is covered with the cooper coating (thermal conductive film), the temperature difference on the cross section within the deposition head can be reduced and a sufficient equi-thermal property can be secured. That is, by forming the thermal conductive film on the surface having the heater, the number of heaters can be reduced and the equi-thermal property can be secured, resulting in a cost reduction. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure can be applied to, for example, a deposition head used for depositing an organic film in manufacturing an organic EL device and a deposition apparatus including the deposition head.