Patent Publication Number: US-2012031338-A1

Title: Susceptor and apparatus for cvd with the susceptor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 10-2010-0076367, filed on Aug. 9, 2010, in the Korean Intellectual Property Office, the of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     Example embodiments of the following description relate to a susceptor and a chemical vapor deposition (CVD) apparatus with the susceptor. 
     2. Description of the Related Art 
     A light emitting diode (LED) is a semiconductor device that converts an electrical current into light. Manufacturing processes for the LED includes an epiwafer manufacturing process, a chip manufacturing process, a packaging process, and a modularizing process. 
     The epiwafer manufacturing process manufactures an epiwafer by growing a GaN-based crystal on a substrate using a metal organic chemical vapor deposition (MOCVD) apparatus. 
     Generally, the substrate is supported by a satellite disc mounted to a susceptor of the MOCVD apparatus. 
     When separated from the susceptor, the substrate may be lifted by a robot arm. However, when the robot arm directly lifts the substrate, the substrate may be damaged due to a sudden temperature change. Therefore, the substrate is usually transferred along with the satellite disc. 
     Afterwards, the satellite disc is separated from the substrate and returned to the susceptor. Here, the satellite disc in being returned to the susceptor needs to be seated in a correct position of the susceptor. 
     SUMMARY 
     According to example embodiments, there may be provided a susceptor for a chemical vapor deposition (CVD) apparatus capable of efficiently positioning a substrate supporting unit, such as a satellite disc, being returned to the susceptor. 
     According to example embodiments, there may be also be provided a susceptor for a CVD apparatus capable of positioning a substrate supporting unit being returned to the susceptor, without using a pin. 
     The foregoing and/or other aspects are achieved by providing a susceptor including a main body configured to include a mounting unit having an uneven plane; and a substrate supporting unit configured to be seated on the mounting unit, wherein a bottom surface of the substrate supporting unit has a shape corresponding to a shape of the mounting unit, and the mounting unit includes a gas discharge hole, to discharge gas from the substrate supporting unit. 
     The foregoing and/or other aspects are achieved by providing an apparatus for CVD, including a reaction chamber configured to be supplied with a reaction gas; and a susceptor configured to include a main body, rotatively mounted to the reaction chamber, and a substrate supporting unit, removably connected to the main body, wherein the main body is provided with a mounting unit including an inclined surface, and the substrate supporting unit is provided with an inclined surface corresponding to the inclined surface of the mounting unit. 
     Additional aspects, features, and/or advantages of example embodiments will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects and advantages will become apparent and more readily appreciated from the following description of the example embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  illustrates a plan view of a susceptor for a chemical vapor deposition (CVD) apparatus, according to example embodiments; 
         FIG. 2  illustrates a sectional view of the susceptor for the CVD apparatus; 
         FIG. 3  illustrates a sectional view of the susceptor shown in  FIG. 2 , where a substrate supporting unit is separated; 
         FIG. 4  illustrates a bottom perspective view of the substrate supporting unit; 
         FIG. 5  illustrates a sectional view of a susceptor for a CVD apparatus, according to other example embodiments; 
         FIG. 6  illustrates a sectional view of the susceptor shown in  FIG. 5 , where a substrate supporting unit is separated; and 
         FIG. 7  illustrates a bottom perspective view of the substrate supporting unit; 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to example embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. Example embodiments are described below to explain the present disclosure by referring to the figures. 
       FIG. 1  illustrates a plan view of a susceptor  20  for a chemical vapor deposition (CVD) apparatus  1 , according to example embodiments.  FIG. 2  illustrates a sectional view of the susceptor  20  for the CVD apparatus  1 .  FIG. 3  illustrates a sectional view of the susceptor  20  shown in  FIG. 2 , where a substrate supporting unit  22  is separated.  FIG. 4  illustrates a bottom perspective view of the substrate supporting unit  22 . 
     Referring to  FIGS. 1 through 4 , the CVD apparatus  1  may include a reaction chamber  10  to supply a space where a chemical reaction is performed, the susceptor  20  to mount at least one substrate (not shown), a heat source  30  to heat the susceptor  20 , and a transfer unit  40  to transfer the substrate supporting unit  22 . 
     The reaction chamber  10  includes an inlet  11  to allow passage of the substrate supporting unit  22 , a reaction gas supply unit  12  to supply a reaction gas, and an outlet  13  to discharge a waste gas remaining after the chemical reaction between the reaction gas and the substrate. 
     The reaction chamber  10  may be a cylindrical structure that supplies an inner space of a predetermined size. In addition, the reaction chamber  10  may be made of a metal which is highly abrasion-resistant and corrosion-resistant. An insulating material may be provided to an inner circumference of the reaction chamber  10  so that the reaction chamber  10  is resistant to a high temperature. 
     The reaction gas supply unit  12  may be disposed at an upper end of the reaction chamber  10 . The reaction gas supply unit  12  may extend downward from the upper end of the reaction chamber  10 . A lower end of the reaction gas supply unit  12  may extend up to a position near a center of a main body  21  of the susceptor  20 . 
     A pipe may be provided inside the reaction gas supply unit  12  to allow the reaction gas to flow. The reaction gas may include Mo, NH 3 , H 2 , N 2 , and the like. The reaction gas may flow in a vertical direction within the reaction gas supply unit  12  and bend to a horizontal direction at the lower end of the reaction gas supply unit  12 . Accordingly, the reaction gas may be discharged from the reaction gas supply unit  12  in the horizontal direction and then flow in the horizontal direction into an upper portion of the main body  21 . 
     As the reaction gas flowing in through the reaction gas supply unit  12  reacts with the substrate, an epitaxial layer may be vapor-deposited and grown on an upper surface of the substrate. 
     The susceptor  20  may include the main body  21 , and the substrate supporting unit  22 , removably connected to the main body  21 . 
     The main body  21  may be composed of graphite coated with carbon or silicon carbide (SiC). The main body  21  may have a disc shape to be easily rotated in the reaction chamber  10 . 
     An upper surface of the main body  21 , may include a mounting unit  23  on which the substrate supporting unit  22  is seated. A plurality of the mounting units  23  may be arranged co-planarly at uniform intervals in a circumferential direction with respect to a center of the main body  21 . 
     The mounting unit  23  may include an uneven surface to minimize escape of the substrate supporting unit  22  from the main body  21  during a return of the substrate supporting unit  22 . More specifically, the mounting unit  23  may protrude from the upper surface of the main body  21 . For example, the mounting unit  23  may have a conical shape. Accordingly, a pointed tip  231  may be formed in a center of the mounting unit  23 , while an inclined surface is formed around the pointed tip  231 . The inclined surface may be inclined downward in a direction from the pointed tip  231  to a periphery. 
     The mounting unit  23  may include a gas discharge hole  232  adapted to discharge gas. The gas discharge hole  232  may be disposed on the inclined surface of the mounting unit  23 . The gas discharge hole  232  may be at least three in number. Through the gas discharge hole  232 , gas may be discharged in an upward direction. Therefore, the gas may support the substrate supporting unit  22  vertically. The gas may be diverted by a bottom surface of the substrate supporting unit  22  and therefore discharged to a side of the substrate supporting unit  22 . Therefore, the substrate supporting unit  22  may be separated by a predetermined interval from the main body  21 . That is, a predetermined gap G is formed between the substrate supporting unit  22  and the main body  21 . The gap G may be constantly maintained because a weight of the substrate supporting unit  22  and a supporting force of the gas supporting the substrate supporting unit  22  are balanced. 
     Exemplarily, the gas discharged through the gas discharge hole  232  does not affect the crystal growth on the substrate. Considering this, the gas may be nitrogen or hydrogen. 
     A rotational shaft  210  may be connected to a lower surface of the main body  21 . A driving source such as a motor may be connected to the rotational shaft  210 . The main body  21  may be rotated integrally with the rotational shaft  210 . 
     The main body  21  may include a gas supply pipe  24  disposed therein to supply the gas being discharged through the gas discharge hole  232 . The gas supply pipe  24  may supply the gas from an external gas source (not shown) provided at the outside of the reaction chamber  10  to the gas discharge hole  232 . As shown in  FIG. 2 , the gas supply pipe  24  may be connected to the external gas source through the rotational shaft  210  to prevent twist of the gas supply pipe  24  caused by rotation of the main body  21 . 
     The substrate supporting unit  22  may be seated on the mounting unit  23 . In the same manner as the main body  21 , the substrate supporting unit  22  may be made of carbon coated with SiC. In addition, the substrate supporting unit  22  may have a disc shape to be easily rotated on the main body  21 . 
     The substrate may be seated on an upper surface  222  of the substrate supporting unit  22 . The upper surface  222  may be plane. Materials of the substrate are not specifically defined. Therefore, a dielectric substrate made of sapphire or spinel (MgAl 2 O 4 ), a semiconductor substrate made of SiC, Si, ZnO, GaAs, or GaN, and a conductive substrate may be used as the substrate. However, it is exemplary to use a sapphire substrate when manufacturing a horizontal semiconductor LED as in the present embodiments. According to a chemical reaction between the substrate and the reaction gas, a GaN-based crystal may grow on the substrate. 
     The substrate supporting unit  22  may be rotated on the main body  21  by viscosity of the gas flowing through the gap G. The gas discharge hole  232  may discharge the gas in an oblique direction to facilitate rotation of the substrate supporting unit  22 . 
     Accordingly, the substrate is rotated by rotation of the substrate supporting unit  22  and, simultaneously, revolved by rotation of the main body  21 . As a result, the crystal may grow more uniformly. Also, since the substrate supporting unit  22  rotates with the predetermined gap G from the main body  21 , frictional damage and deformation of those parts may be prevented, while achieving stable vapor-deposition. 
     The bottom surface of the substrate supporting unit  22  may be recessed in a shape corresponding to the mounting unit  23 . Therefore, the bottom surface of the substrate supporting unit  22  may be recessed in the conical shape corresponding to the mounting unit  23 . To be more specific, the bottom surface of the substrate supporting unit  22  may include a recessed portion  224  and a center point  225 . Also, an inclined surface may be formed around the center point  225 . Accordingly, the mounting unit  23  may be received in the substrate supporting unit  22 . 
     According to the above configuration, even though the substrate supporting unit  22  being returned to the mounting unit  23  is seated on a wrong position which is a little deviated from the center of the mounting unit  23 , the wrong position may be corrected. Also, since the substrate supporting unit  22  is separated from the mounting unit  23  by a predetermined interval by the gas discharged from the gas discharge hole  232 , the position correction of the substrate supporting unit  22  may be more conveniently achieved. In other words, since the substrate supporting unit  22  and the mounting unit  23  have corresponding shapes to each other and since the substrate supporting unit  22  is floated by the gas, positioning of the substrate supporting unit  22  being returned may be more easily performed, accordingly reducing an error rate during returning of the substrate supporting unit  22 . 
     The heat source  30  supplies heat to an inside of the reaction chamber  10 . Specifically, the heat source  30  is disposed near the susceptor  20  to supply the susceptor  20  with the heat for heating the substrate. Any of an electric heater, a high frequency induction heater, an infrared radiation heater, and a laser heater may be used as the heat source  30 . 
     The transfer unit  40  may include a grip portion  41  to grip the substrate supporting unit  22 , and an extension portion  42  extending from the grip portion  41 . The transfer unit  40  may be automatically controlled like a robot arm. The transfer unit  40  may transfer the substrate along with the substrate supporting unit  22  to the outside of the reaction chamber  10 , or return the substrate supporting unit  22  separated from the substrate to the reaction chamber  10 . 
     Hereinafter, an operation of the example embodiments will be described. 
     When the GaN-based epitaxial layer is grown and vapor-deposited on a surface of the substrate, an object of the vapor-deposition, that is, the substrate is placed on the substrate supporting unit  22 . 
     In this case, the main body  21  may be rotated in one direction by a driving force of the rotational shaft  210 . The substrate supporting unit  22  is rotated by the viscosity of the gas discharged through the gas discharge hole  232 . 
     In addition, the reaction gas supply unit  12  may supply the reaction gas mixedly containing a source gas such as trimethylgallium (TMGa) and a carrier gas such as ammonia. 
     The heat source  30  may supply heat to the reaction chamber  10 . 
     Accordingly, the reaction gas is brought into uniform contact with the surface of the substrate, thereby uniformly forming a thin film on which a nitride is grown, that is, the semiconductor epitaxial layer. 
     Next, the grip portion  41  of the transfer unit  40  may grip the substrate supporting unit  22  seated on the mounting unit  23  and transfer the substrate and the substrate supporting unit  22  together. Since the substrate supporting unit  22  is separated from the mounting unit  23  by the predetermined interval, the transfer unit  40  may transfer the substrate supporting unit  22  efficiently. 
     After the substrate supporting unit  22  is transferred to the outside of the reaction chamber  10 , the substrate is separated from the substrate supporting unit  22 . 
     Next, the substrate supporting unit  22  may be returned to the mounting unit  23 . The mounting unit  23  is protruded whereas the substrate supporting unit  22  is recessed in a shape corresponding to the shape of the mounting unit  23 . The substrate supporting unit  22  is floated by the gas discharged from the gas discharge hole  232 . Therefore, even when the substrate supporting unit  22  is returned to a wrong position deviated from the center of the mounting  23 , the wrong position of the substrate supporting unit  22  may be corrected. 
     Hereinafter, other example embodiments will be described. While configurations of only a substrate supporting unit and a mounting unit are distinctive, the other features of the present embodiments are the same as those of the previous embodiments and will not be repeatedly explained. 
       FIG. 5  illustrates a sectional view of a susceptor for a CVD apparatus, according to other example embodiments.  FIG. 6  illustrates a sectional view of the susceptor shown in  FIG. 5 , where a substrate supporting unit is separated.  FIG. 7  illustrates a bottom perspective view of the substrate supporting unit. 
     Referring to  FIGS. 5 to 7 , a mounting unit  26  of the present example embodiments may be recessed from an upper surface of the main body  21 . For example, the mounting unit  26  may be recessed in a funnel shape tapered to have a wide upper portion and a narrow lower portion. According to this, a lowermost point  261  may be formed in a center of the mounting unit  26 . An inclined surface may be formed around the lowermost point  261 . The inclined surface may be inclined upward from the lowermost point  261  toward a periphery. 
     A gas discharge hole  262  may be formed on the mounting unit  26  to discharge gas. More specifically, the gas discharge hole  262  may be formed on the inclined surface of the mounting unit  26 . 
     The substrate may be seated on an upper surface  282  of a substrate supporting unit  28  according to the present example embodiments. The upper surface  282  may be plane. 
     A bottom surface of the substrate supporting unit  28  may be protruded in a shape corresponding to the mounting unit  26 . That is, the bottom surface may be protruded in a conical shape to be received in the mounting unit  26 . More specifically, the bottom surface of the substrate supporting unit  28  may include a protruded portion  283  and a center point  285 . Also, an inclined surface may be formed around the center point  285 . According to this, the substrate supporting unit  28  may be received in the mounting unit  26 . 
     Thus, since the substrate supporting unit  28  and the mounting unit  26  have corresponding shapes to each other and since the substrate supporting unit  28  is floated by the gas, positioning of the substrate supporting unit  28  being returned may be more easily performed, accordingly reducing an error rate during returning of the substrate supporting unit  28 . 
     According to the example embodiments, when a substrate supporting unit is returned, accurate positioning of the substrate supporting unit may not be required. 
     In addition, the substrate supporting unit may be prevented from being deformed by friction with a pin. Therefore, vapor-deposition may be stably performed. 
     Although example embodiments have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these example embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined in the claims and their equivalents.