Abstract:
Disclosed is an apparatus for manufacturing semiconductors, to be used for various processes in semiconductor manufacture processing, such as the forming of layers on wafers. A tube has a processing space therein and a discharge hole at a side thereof. A boat can be loaded and unloaded through a lower opening of the tube. Susceptors are vertically separated from one another and supported within the boat, have a central hole defined in the respective centers of rotation thereof, and have a plurality of wafers stacked around a central perimeter on the respective top surfaces thereof. A supply tube is installed at the top of the boat and passes through each central hole of the susceptors, and defines discharge holes for discharging processing gas supplied from the outside onto each top surface of the susceptors.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of International Patent Application No. PCT/KR2010/004104, filed on Jun. 24, 2010, which claims the benefit of Korean Patent Application No. 10-2009-0064952, filed on Jul. 16, 2009, the entire disclosure of which are incorporated herein by reference for all purposes. 
     BACKGROUND 
     1. Field 
     The following description relates to an apparatus for manufacturing a semiconductor, which is used in the course of various semiconductor manufacturing procedures including forming a film on a wafer. 
     2. Description of the Related Art 
     Generally, a semiconductor manufacturing apparatus is used for various semiconductor manufacturing procedures including annealing, diffusion, oxidation, and chemical vapor deposition. Furnaces as semiconductor manufacturing apparatuses can be divided into two kinds in which vertical or horizontal furnaces are used. 
     As a low pressure chemical vapor deposition furnace, a vertical type furnace is more often employed than a horizontal type furnace because the vertical type furnace produces fewer fine impurities such as particles than the horizontal type furnace. In addition, the vertical type furnace has a process tube positioned vertically so that a bottom area occupied by a lower strut can be beneficially reduced. 
     A conventional vertical type furnace will be described with reference to  FIG. 1 . 
     Referring to  FIG. 1 , a vertical type furnace  10  includes a heating chamber  11  having a heater, an outer tube  12 , an inner tube  13 , a flange  14 , a boat  15 , and a nozzle  16 . The outer tube  12  is installed inside the heating chamber  11 , the inner tube  13  is installed inside the outer tube  12 , and the outer tube  12  and the inner tube  13  are mounted on the flange  14 . The boat  15  is mounted in the inner tube  13  and in the boat, wafers W are loaded. The nozzle  16  is installed on the flange  14  and a process gas is injected through the nozzle  16  from an external source. The process gas ejected from the nozzle  16  flows between the boat  15  and the inner tube  13  to form a film on each wafer. 
     In the example shown in  FIG. 1 , the wafers W are loaded vertically in the boat  15  one by one. Thus, to increase productivity by processing more wafers W at one time, a larger number of wafers W should be loaded. Then, a height of the loaded wafers W is increased and accordingly the time for the process gas to form a film on each wafer W can be increased. This may restrict the increase of the number of wafers W to be processed at one time. 
     Additionally, in the vertical type furnace  10  shown in  FIG. 1 , after the process gas is supplied from a lower portion forms a film on each wafer W while flowing between the boat  15  and the inner tube  13 , residual gas passes over a top of the inner tube  13  and is discharged externally through a space between the inner tube  13  and the outer tube  12 . In the above case, since the process gas is supplied to the wafers W while moving upwards, not all wafers have a uniform film formed thereon. 
     SUMMARY 
     In one general aspect, provided is an apparatus for manufacturing a semiconductor, the apparatus comprising: a tube configured to have a process space inside and a drain outlet at one end; a boat configured to be moved in and out of the tube through a open lower portion of the tube; a plurality of susceptors configured to be arranged apart from one another in a vertical direction, and each having a center hole on a rotation axis and having a top surface on which a plurality of wafers are loaded around a center; and a supply pipe configured to be installed to penetrate the center hole of each susceptor from a top of the boat and to have ejection nozzles, each ejecting a process gas provided from an external source to the top surface of each susceptor. 
     A plurality of wafers may be loaded on each of the susceptors arranged in a vertical direction, so that more wafers can be processed at one time compared to a conventional vertical furnace. Thus, the productivity can be increased. 
     In addition, the process gas may be ejected onto the top surface of each susceptor, and thus it is possible for the process gas to be provided to all wafers more evenly regardless of a location, compared to the conventional vertical furnace. Hence, a uniform film can be formed on each wafer. 
     Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of an example of a vertical type furnace according to the prior art. 
         FIG. 2  is a cross-sectional view of an apparatus for manufacturing a semiconductor according to an exemplary embodiment of the present invention. 
         FIG. 3  is a perspective view of a susceptor shown in  FIG. 2 . 
         FIG. 4  is a cross-sectional view showing an inclined top surface of the susceptor of  FIG. 2 . 
         FIG. 5  is a cross-sectional view showing an inclined ejection direction of an ejection nozzle of  FIG. 2 . 
         FIG. 6  is a plan view showing how the susceptor of  FIG. 2  rotates along with the boat with respect to the supply pipe. 
         FIGS. 7 and 8  are a horizontal cross-sectional view and a vertical cross-sectional view of another example of the supply pipe shown in  FIG. 2 . 
     
    
    
     Throughout the drawings and the detailed description, unless otherwise described, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. The relative size and depiction of these elements may be exaggerated for clarity, illustration, and convenience. 
     DETAILED DESCRIPTION 
     The following description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. Accordingly, is various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be suggested to those of ordinary skill in the art. Also, descriptions of well-known functions and constructions may be omitted for increased clarity and conciseness. 
       FIG. 2  illustrates an example of a cross-sectional view of an apparatus for manufacturing a semiconductor.  FIG. 3  illustrates an example of a perspective view of one of susceptors included in the apparatus of  FIG. 2 . 
     Referring to  FIGS. 2 and 3 , the apparatus  100  for manufacturing a semiconductor includes a tube  110 , a boat  120 , susceptors  130 , a supply pipe  140 , and a baffle  150 . 
     The tube  110  has a space for processing and a drain outlet  103  at one end. The process may include annealing, diffusion, oxidation, chemical vapor deposition, and the like. The tube  110  is supplied with process gas through the supply pipe  140 . The tube  110  may be configured to have an upper portion closed and a lower portion open. The boat  120  may be moved in and out of the tube  110  through the open lower portion of the tube  110 . The drain outlet  103  may be disposed on a lower end of the tube  110  to discharge the process gas out of the tube  110 . The boat  120  may be moved in and out of the tube  110  by an elevating device (not shown). When the boat  120  is placed in the tube  110 , the inner space of the tube  110  may be sealed by a sealing unit  102 . 
     The sealing unit  102  may be interposed between a flange  111  and a boat supporting stand  136 . The flange  111  extends outwards from a lower edge of the tube  110 , and the boat supporting stand  136  is formed to support the boat  120  at the bottom of the boat  120 . 
     The heating chamber  101  may be disposed to enclose around the tube  110 . The heating chamber  101  heats up the tube  110  and maintains a temperature inside the tube  110  to a set temperature. To this end, the heating chamber  101  may include a heater (not shown). 
     A plurality of susceptors  130  may be provided. The susceptors  130  are disposed in the boat  120  a predetermined distance from one another in a stacked manner. The susceptors  130  may be supported by projection portions which are formed in the boat  120  to be spaced a predetermined distance apart from one another in a vertical direction. 
     Each susceptor  130  may have a center hole  132  for the supply pipe  140  to be inserted and installed therein. Each susceptor  130  is configured to have a plurality of wafers W disposed on its top surface around the center hole  132 . 
     To this end, as shown in  FIG. 3 , each susceptor  130  may be in a circular form. Also, each susceptor  130  may have wafer receiving portions  131  to house the wafers W. Each of the wafer receiving portions  130  may be formed as a recess to receive the wafer W. 
     The supply pipe  140  may be installed to penetrate the center holes  132  of the susceptors  130  from the top of the boat  120 . The supply pipe  140  is installed detachably from the susceptors  130  by penetrating the center holes  132 . Therefore, while the supply pipe  140  is fixed to the tube  110 , the susceptors  130  supported by the boat  120  can be freely moved in and out through the open lower portion of the tube  110 . 
     The supply pipe  140  is provided with process gas from an external source and ejects the process gas to supply it to the wafers W. The supply pipe  140  may have an upper end which penetrates the tube  110  and the heating chamber  101  so that the supply pipe  140  can be connected with an external gas provider, and be provided with the process gas from the external gas provider. In another example, the supply pipe  140  may have an upper end connected with a gas supply channel disposed inside the tube  110  to be provided with the process gas. The gas supply channel may be connected with an external gas provider. 
     The supply pipe  140  has a plurality of ejection nozzles  140   a  to eject the process gas to a top surface of each susceptor  130 . The ejection nozzles  140   a  may be assigned to the susceptors  130  one by one or in groups. 
     Operations of the above apparatus  100  will now be described below. 
     First, while an empty boat  120  is moved out of the tube  110  by an elevating device, the susceptors  130  having wafers W loaded thereon are loaded into the boat  120 . Once the susceptors  130  are completely loaded in the boat  120 , the boat  120  is moved into the tube  110  by the elevating device. The heating chamber  101  heats up the tube  110  to maintain the inside of the tube  110  at a set temperature. Heating the tube  110  may precede moving the boat  120  inside the tube  110 . 
     While the boat  120  is placed inside the tube  110 , the process gas is ejected into the tube  110  through the supply pipe  140 . The process gas is ejected toward the top surface of each susceptor  130  through the ejection nozzles  140   a  of the supply pipe  140  to be provided to the wafers W. The process gas provided to the wafers W may form a film on each wafer W. Once the film is completely formed on each wafer W, the boat  120  is withdrawn from the tube  110  by the elevating device, and the susceptors  130  are unloaded from the boat  120 . 
     As described above, each of the susceptors  130  arranged in a stacked manner may have a plurality of wafers W loaded thereon. Accordingly, compared to a case where wafers W are loaded on the susceptors  130  one by one, the susceptors  130  in the examples shown in  FIGS. 2 and 3  can process more wafers W at a time under the assumption that the heights of the loaded wafers W are the same in both cases. Thus, productivity can be increased. 
     Furthermore, in the examples shown in  FIGS. 2 and 3 , the process gas may be ejected to the top surface of each susceptor  130 . Hence, compared to a case where process gas is supplied to the wafers W while being moved upwardly from a bottom to a top of the tube  110 , the process gas can be uniformly supplied to all wafers W regardless of their locations in the example shown in  FIG. 2 . Therefore, films can be uniformly formed on the individual wafers W. 
     Meanwhile, to form a uniform film on the wafer W, as shown in  FIG. 4 , the ejection nozzles  140   a  may be formed to eject the process gas horizontally. In addition, in each susceptor  130 , a surface on which the wafer W is loaded may be inclined upwardly from the center of the susceptor  130  to the side edge. Here, the inclination angle θ of each susceptor  130  may be set to form a uniform film on the wafer W. In this case, only the region on the surface of the susceptor  130  on which the wafer W is placed may be inclined, but the entire top surface of the susceptor  130  may be inclined as shown in  FIG. 3 . 
     Since the wafers W are arranged along the circumference of the supply pipe  140 , if the process gas ejected from the ejection nozzles  140   a  is applied in parallel to the top surfaces of the wafers W, a region of each wafer W distant from the ejection nozzles  140   a  may be provided with less process gas than a region close to the ejection nozzles  140   a . However, each wafer W is disposed to be inclined upwardly toward the outer edge, and thus the process gas is capable of staying longer on the region distant from the ejection nozzles  140   a . Thus, the process gas can be uniformly provided on the wafer W, so that a uniform film can be formed on the wafer W. 
     As another example, to form a uniform film on each wafer W, as shown in  FIG. 5 , the susceptors  130  may have horizontal surfaces on which the wafers W are loaded, and the ejection nozzles  140   a  may be formed to eject the process gas at a predetermined angle toward the susceptors  130 . Here, the inclination angle θ of the ejection nozzles  140   a  may be set to form the uniform film on each wafer W. The effect of the inclination is the same as described above. 
     As yet another example, although not illustrated, a region of each susceptor  130  on which the wafer W is loaded is inclined upwardly from the center to the edge of the susceptor  130 , and the ejection nozzles  140   a  may be formed to eject the process gas at a predetermined angle to each susceptor  130 . In this case, the inclination angle of the susceptor  130  and the inclination angle of the ejection nozzles  140   a  may also be set to form a uniform film on each wafer W. 
     The boat  110  may be rotated by a rotation device (not shown) as illustrated in  FIG. 6 . For example, the boat  110  may be coupled with the rotation device to rotate. Due to the rotation of the boat  110 , the susceptors  130  may be capable of being rotated with respect to the supply pipe  140 . Accordingly, the process gas ejected from the ejection nozzles  140   a  may be able to be evenly provided to the wafers W which are rotated while on the susceptors  130 . 
     When the susceptors  130  are rotated, the process gas ejected from the ejection nozzles  140   a  is likely to flow towards the outer edge of the susceptor  130  due to a rotational centrifugal force. In this case, because the centers of the respective wafers W are located off the rotation center of the susceptors  130 , the process gas may not be evenly provided to the wafers W. Thus, the thickness of the film formed on each wafer W may be differed according to whether a region of the film is close to or distant from the center of the susceptor  130 . That is, the film may not be formed with a uniform thickness on the wafers W. 
     To overcome the above problem, as shown in  FIG. 2 , a supplementary supply pipe  160  may be further included in the tube  110  to additionally provide the process gas. The supplementary supply pipe  160  supplements the process gas to the wafers W located at the outer edge of each susceptor  130 , so that the films can be formed with a uniform thickness on the wafers W. The supplementary supply pipe  160  includes ejection nozzles  160   a . The ejection nozzles  160   a  may be formed on the supplementary supply pipe  160  to eject the process gas onto the top surfaces of the susceptors  130 . 
     The baffle  150  may be interposed between the tube  110  and the boat  120  to guide the residual gas in the tube  110  to the drain outlet  103 . The baffle  150  guides the residual gas, which is left after forming the films on the wafers W, to the drain outlet  103 . 
     The baffle  150  may be formed in a cylinder shape with upper and lower open ends. The baffle  150  has the upper open end apart from the tube  110  and the lower open end fixed to the is flange  111  to form a space with an open top and a closed bottom between the baffle  150  and the tube  110 . The drain outlet  103  may be formed on the lower portion of the space between the baffle  150  and the tube  110  and be open to the outside of the tube  110 . Accordingly, residual gas is capable of being guided to the space between the baffle  150  and the tube  110 , and then discharged externally through the drain outlet  103 . 
     The baffle  150  may have a plurality of baffle holes  151  corresponding to the respective heights of the susceptors  130 . For example, the baffle holes  151  may be positioned at the same height as the top surfaces of the susceptors  1360 . Accordingly, the residual process gas left on the top surface of the susceptor  130  after forming the film on each susceptor  130  can be promptly discharged. 
     As shown in  FIGS. 7 and 8 , the supply pipe  240  may have a triple-pipe configuration, including a first supply channel  241 , a second supply channel  242 , and a third supply channel  243 . The first to third supply channels  241 ,  242 , and  243  may extend vertically, and be disposed concentrically. Here, the third supply channel  243  may be interposed between the first supply channel  241  and the second supply channel  242 . 
     The first supply channel  241  may be provided with first process gas from an external source. In this case, the first supply channel  241  may have a first ejection nozzle  241   a  to eject the first process gas. The second supply channel  242  may be provided with second process gas from the external source. The second supply channel  242  may have a second ejection nozzle  242   a  to eject the second process gas. 
     The third supply channel  243  may be provided with cooling medium from an external source. The cooling medium may be a gas, a liquid, or a solid state. The cooling medium provided to the third supply channel  243  may prevent the first and second process gases from being dissociated while the first and second process gases are respectively flowing through the first and second supply channels  241  and  242 . 
     When metal organic chemical vapor deposition (MOCVD) is performed in the tube  110  (see  FIG. 2 ) and a Gallium Nitride (GaN) film is formed on each wafer W, the first process gas may be one of Trimethylgallium and ammonia, and the second process gas may be the other. 
     In the case described above, if the cooling medium is provided to the first supply channel  241  or the second supply channel  242 , Trimethylgallium which requires to be refrigerated more than ammonia may be provided to the third supply channel  243  that is close to the cooling medium. 
     In implementations, the supplementary supply pipe may have a triple-pipe configuration, similar to the supply pipe which has a triple-pipe configuration as described above. Alternatively, the supply pipe and the supplementary supply pipe may have a single-pipe configuration or a double-pipe configuration. For example, if process gases are mixed outside the tube and then the mixture of the process gases is provided to the tube, the supply pipe and the supplementary supply pipe may have a single pipe configuration, and if process gases are provided through individual supply channels, the supply pipe and the supplementary pipe may have a double-pipe configuration. 
     A number of examples have been described above. Nevertheless, it will be understood that various modifications may be made. For example, suitable results may be achieved if the described techniques are performed in a different order and/or if components in a described system, architecture, device, or circuit are combined in a different manner and/or replaced or supplemented by other components or their equivalents. Accordingly, other implementations are within the scope of the following claims.