Patent Publication Number: US-2015079764-A1

Title: Vapor phase growth apparatus and vapor phase growth method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2013-191116, filed Sep. 13, 2013; the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a vapor phase growth apparatus and a vapor phase growth method. 
     BACKGROUND 
     A vapor phase growth apparatus used for the fabrication of semiconductor devices such as a light emitting device and a High Electron Mobility Transistor (HEMT) is one of important apparatuses when a high quality film is formed. Particularly, in an apparatus for performing metal organic chemical vapor deposition (MOCVD), a multitude of wafers may be processed at a time for the purpose of mass production. In a vapor phase growth apparatus, a plurality of substrate holding portions is provided on a susceptor on which a wafer is arranged. Film formation may be performed on a multitude of wafers at a time by arranging a wafer on each of a plurality of substrate holding portions. 
     The susceptor has a rotating mechanism in order to perform uniform film formation on a plurality of wafers on the susceptor. Further, each of the substrate holding portions on the susceptor also has a rotating mechanism. The substrate holding portion is rotatably supported on the susceptor through a bearing. In the vapor phase growth apparatus, when raw-material gas flows into the housing of the bearing, and deposit adheres to the surface of the bearing, the rotation of the substrate holding portion is affected. In the vapor phase growth apparatus, it is important to keep the function of the bearing for a long time. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  and  FIG. 1B  are schematic block diagrams illustrating a configuration of a vapor phase growth apparatus according to a first embodiment. 
         FIG. 2A  and  FIG. 2B  are schematic cross-sectional views illustrating a configuration of a substrate holding portion according to the first embodiment. 
         FIG. 3A  and  FIG. 3B  are schematic plane views illustrating a configuration of the substrate holding portion and a configuration of a tray portion, respectively, according to the first embodiment. 
         FIG. 4A  and  FIG. 4B  are schematic plane views illustrating a shape of a blade portion according to the first embodiment. 
         FIG. 5A  and  FIG. 5B  are schematic cross-sectional views illustrating a configuration of a vapor phase growth apparatus according to a second embodiment. 
         FIG. 6A  and  FIG. 6B  are schematic cross-sectional views illustrating each configuration of non-contact sealing members according to the second embodiment. 
         FIG. 7  is a flowchart illustrating a vapor phase growth method according to a third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     It is an object of an exemplary embodiment of the present disclosure to provide a vapor phase growth apparatus and a vapor phase growth method capable of maintaining function of a bearing that supports a substrate holding portion for a long time. 
     According to one embodiment, a vapor phase growth apparatus includes a susceptor in a chamber, the susceptor configured to rotate on an axis perpendicular to a surface of the susceptor, a plurality of substrate holding portions above the susceptor, each of the substrate holding portions configured to revolve around the axis by the rotation of the susceptor and configured to rotate circumferentially, a plurality of bearings arranged in a housing between the susceptor and the substrate holding portion, and a plurality of blade portions on the outer periphery of the substrate holding portion, each of the blade portions extending radially from the center of the substrate holding portion. 
     According to another embodiment, a vapor phase growth apparatus includes a susceptor in a chamber, the susceptor configured to rotate on an axis perpendicular to a surface of the susceptor, a plurality of substrate holding portions above the susceptor, each of the substrate holding portions configured to revolve around the axis by the rotation of the susceptor and configured to rotate circumferentially, a plurality of bearings arranged in a housing between the susceptor and the substrate holding portion, and a non-contact sealing portion including a part of susceptor, a part of the substrate holding portion, and a gap between the substrate holding portion and the susceptor and provided outside the housing. 
     Exemplary embodiments of the present disclosure will be described below with reference to the accompanying drawings. In the following description, the same symbols are assigned to the same elements and their description is not repeated as appropriate. 
     First Embodiment 
       FIG. 1A  and  FIG. 1B  are schematic block diagrams illustrating a configuration of a vapor phase growth apparatus according to a first embodiment.  FIG. 1A  shows a schematic cross-sectional view of a vapor phase growth apparatus  110  according to the present embodiment.  FIG. 1B  shows a schematic plan view of a susceptor  10  and a substrate holding portion  20 . 
     As shown in  FIG. 1A , the vapor phase growth apparatus  110  according to the present embodiment includes the susceptor  10 , the substrate holding portion  20 , a plurality of bearings  30  and a plurality of blade portions  40 . The vapor phase growth apparatus  110  is an MOCVD apparatus, for example. 
     The vapor phase growth apparatus  110  further includes a chamber  1  and a heater  50 . The susceptor  10  rotates around an axis c1 in the chamber  1 . As shown in  FIG. 1B , the susceptor  10  is disk-like, for example, and a rod-like support member  5  is attached to the center of the disk. The axis c1 represents the axial center of the support member  5 . The susceptor  10  is rotated around the axis c1 in a circumferential direction D1 by a driver, not shown. 
     The substrate holding portion  20  is provided on the susceptor  10 . In examples shown in  FIG. 1A  and  FIG. 1B , the plurality of substrate holding portions  20  are provided. A plurality of substrate holding portions  20  is arranged on the susceptor  10  on a circumference of centered on the axis c1 at regular intervals. The substrate holding portion  20  is disk-like, for example. Each of the plurality of the substrate holding portions  20  rotates in a circumferential direction D2 along a surface perpendicular to the axis c1 on the susceptor  10 . The rotation of the substrate holding portion  20  includes the revolution caused by the rotation of the susceptor  10  and the rotation of the substrate holding portion  20 . 
     A gear, not shown, is provided on the outer periphery of the disk-like substrate holding portion  20 . The gear of the substrate holding portion  20  engages with a gear provided inside a ring member, not shown, that is arranged so as to surround the outer periphery of the susceptor  10 . When the substrate holding portion  20  revolves caused by the rotation of the susceptor  10 , the gear of the substrate holding portion  20  engages with the gear of the ring member, thus the substrate holding portion  20  rotates on its axis. 
     The bearings  30  are arranged in a housing  35  provided between the susceptor  10  and the substrate holding portion  20 . The bearings  30  are arranged near the outer periphery of substrate holding portion  20  on the side of the susceptor  10 . The substrate holding portion  20  is put on the bearings  30 . In this manner, the substrate holding portion  20  rotates smoothly on the susceptor  10  by the rolling action of the bearings  30 . For example, a wafer W to be processed is provided on the surface of the substrate holding portion  20 . 
     The blade portions  40  are provided on the outer periphery of the substrate holding portion  20 . Each of the blades  40  includes a portion extending radially from the center of the substrate holding portion  20 . 
     In order to perform vapor phase growth using the vapor phase growth apparatus  110 , first, a wafer W is put on the substrate holding portion  20  on the susceptor  10 , and the susceptor  10  and the substrate holding portion  20  are rotated. Then, the wafer W is heated by the heater  50 . And then, a raw-material gas GS1 is introduced in the chamber  1 . In this manner, the raw-material gas GS1 reacts on the heated wafer W, and a film having prescribed composition is formed according to the component of the raw-material gas. 
       FIG. 2A  and  FIG. 2B  are schematic cross-sectional views illustrating a configuration of a substrate holding portion.  FIG. 2A  shows a schematic cross-sectional view of the entire substrate holding portion  20 , and  FIG. 2B  shows a schematic cross-sectional view of the enlarged outer periphery of the substrate holding portion  20 .  FIG. 3A  and  FIG. 3B  are schematic plane views illustrating a configuration of the substrate holding portion and a tray portion.  FIG. 3A  shows a schematic plane view of the substrate holding portion  20  viewed from a tray portion  12  side (bottom side).  FIG. 3B  shows a schematic plan view of the tray portion  12  viewed from the opposite side (bottom side) to the substrate holding portion  20 . 
     As shown in  FIG. 2A , the susceptor  10  includes a body portion  11  and the tray portion  12 . The tray portion  12  is provided on the bottom side of the substrate holding portion  20 . The tray portion  12  is inserted into a hole in the body portion  11 . The substrate holding portion  20  is arranged on the tray portion  12 . 
     A depressed portion  20   a  is provided in the center of the substrate holding portion  20 . On the other hand, a projecting portion  12   a  is provided in the center of the tray portion  12 . The depressed portion  20   a  in the substrate holding portion  20  is put on the projecting portion  12   a  in the tray portion  12 . The inner diameter of the depressed portion  20   a  is slightly larger than the contour of the projecting portion  12   a.    
     Further, a housing  35  of the bearing  30  is provided between the substrate holding portion  20  and the tray portion  12 . The housing  35  is provided on the tray portion  12  side on the outer periphery of the substrate holding portion  20 . The housing  35  surrounds the outside of the projecting portion  12   a  in the tray portion  12 . The predetermined number of the bearings  30  is arranged in the housing  35 . For example, the bearings  30  are arranged on the circumference through the center of the housing  35  by a ratio of approximately 60% to 80% of the circumference. 
     The diameter of each of the bearings  30  is slightly larger than a height of the projecting portion  12   a  in the tray portion  12 . Therefore, when the bearings  30  are arranged on the housing  35 , and the substrate holding portion  20  is put on the tray portion  12 , the substrate holding portion  20  is supported by the bearings  30 . When the substrate holding portion  20  is arranged on the tray portion  12  through the bearings  30 , a gap is provided between the inner surface of the depressed portion  20   a  and the outer surface of the projecting portion  12   a . This gap allows the substrate holding portion  20  to rotate smoothly on the tray portion  12  by the rolling action of the bearing  30 . 
     A step  21  is provided on the opposite side (surface side) to the tray portion  12  of the substrate holding portion  20 . A wafer W is put on the step  21 . 
     An introduction opening  12   h  for counter gas GS2 is provided in the tray portion  12 . Inert gas such as N 2  is used for the counter gas GS2. The counter gas GS2 inhibits the gas GS1 for growth introduced in the chamber  1  from flowing into the bottom of the susceptor  10 . 
     The introduction opening  12   h  is a through-hole that reaches the housing  35  of the bearing  30  from the outer peripheral surface (e.g., underside) of the tray portion  12 . As shown in  FIG. 3B , a plurality of introduction openings  12   h  are provided at predetermined intervals along the circumference slightly inside from the outer periphery of the tray portion  12 . It is desirable that the introduction opening  12   h  is arranged inside or outside to the center of the bearing  30  arranged in the housing  35 . This prevents the introduction opening  12   h  from being blocked by the bearings  30 . 
     As shown in  FIG. 3A , the blade portions  40  are provided on the outer periphery of the substrate holding portion  20 . Each of the blade portions  40  has a portion extending radially from the center c2 of the substrate holding portion  20 . The example shown in  FIG. 3A  represents each of the blade portions  40  radially extending on a straight line from the center c2 of the substrate holding portion  20 . 
     When such blade portions  40  are provided, and the substrate holding portion  20  rotates (on its axis), a pressure on the side of the housing  35  centered on the substrate holding portion  20  becomes higher than a pressure on the opposite side to the housing  35 . That is, the rotation of the blade portions  40  generates the pressure difference between the front side and the back side of the substrate holding portion  20 . 
     As shown in  FIG. 2B , the pressure difference generated by the rotation of the blade portions  40  causes the counter gas GS2 introduced from the introduction opening  12   h  to flow from the housing  35  to the front side of the substrate holding portion  20  through the gap between each of the blade portions  40  and the body portion  11  of the susceptor  10 . 
     When vapor phase growth is performed by the vapor phase growth apparatus  110 , the raw-material gas GS1 is sent into the front side of the substrate holding portion  20 . Here, assuming that the pressure generated by the raw-material gas GS1 flowing from the surface of the substrate holding portion  20  toward the housing  35  is set to be P1, and the pressure generated by the counter gas GS2 flowing from the housing  35  toward the surface of the substrate holding portion  20  is set to be P2 in the gap between the blade portion  40  and the body portion  11  of the susceptor  10 , the blade portions  40  are provided so that the pressure P2 becomes higher than the pressure P1. This inhibits the raw-material gas GS1 from flowing into the housing  35  of the bearing  30  during vapor phase growth processing. 
       FIG. 4A  and  FIG. 4B  are schematic plan views illustrating shapes of another blade portions.  FIG. 4A  shows a schematic plane view of a plurality of blade portions  40 A.  FIG. 4B  shows a schematic plane view of a plurality of blade portions  40 B. Each of the blades  40 A shown in  FIG. 4A  is curved. Each of the blade portions  40 B is tilted with respect to the radial direction. Each of blade portions  40 A and  40 B has a portion extending radially. Various types of blade portions  40  may be used, including a turbo type, a sirocco type and a radial type. The size, shape and the number of the blade portions  40  are suitably determined depending on the size and the rotational frequency of the substrate holding portion  20 , and the relation between the pressures P1 and P2. 
     The vapor phase growth apparatus  110  according to the present embodiment inhibits the raw-material gas GS1 from flowing into the housing  35  of the bearing  30  due to generation of pressure difference by the blade portions  40 , and inhibits deposit due to the raw-material gas GS1 from adhering to the surface of the bearing  30 . 
     Second Embodiment 
     Next, a vapor phase growth apparatus according to a second embodiment will be described.  FIG. 5A  and  FIG. 5B  are schematic cross-sectional views illustrating a configuration of a vapor phase growth apparatus according to the second embodiment.  FIG. 5A  shows a schematic cross-sectional view of the enlarged susceptor  10  and substrate holding portion  20  of a vapor phase growth apparatus  120  according to the second embodiment.  FIG. 5B  shows a schematic cross-sectional view of the enlarged outer periphery of the substrate holding portion  20 . The configurations of the substrate holding portion  20  and the tray portion  12  (susceptor  10 ) on the side of the outer periphery than the housing  35  in the vapor phase growth apparatus  120  according to the second embodiment are different from those in the vapor phase growth apparatus  110  according to the first embodiment. Since other configurations in the vapor phase growth apparatus  120  are similar to those in the vapor phase growth apparatus  110 , description thereof is omitted. 
     As shown in  FIG. 5A , the vapor phase growth apparatus  120  according to the present embodiment includes a non-contact sealing member  60 . The non-contact sealing member  60  is provided between the substrate holding portion  20  and the tray portion  12  and outside the housing  35  of the bearings  30 . 
     In the vapor phase growth apparatus  120 , the non-contact sealing member  60  inhibits raw-material gas GS1 from flowing into the housing  35  of the bearings  30  through the gap between the substrate holding portion  20  and the tray portion  12 . 
     As shown in  FIG. 5B , the non-contact sealing member  60  includes, for example, a labyrinth seal. The labyrinth seal produces a labyrinth effect by forming a gap between the substrate holding portion  20  and the tray portion  12  into a labyrinth configuration. 
     In the non-contact sealing member  60 , the gap between the substrate holding portion  20  and the tray portion  12  includes a first portion  61  and a second portion  62 . The first portion  61  extends from a position  601  in communication with the housing  35  toward the substrate holding portion  20  (upper side). The second portion  62  extends toward the tray portion  12  side than the closest position to the substrate holding portion  20  in the first portion  61 . That is, the first portion  61  rises up from the position  601  in communication with the housing  35 . The second portion  62  falls down from the uppermost position of the first portion  61 . There may be another portion (e.g., a portion where height does not change) between the first portion  61  and the second portion  62 . 
     In the example shown in  FIG. 5B , a plurality of first portions  61  and a plurality of second portions  62  are provided alternately. The more the number of the first portions  61  and the second portions  62  increases, the more the labyrinth effect increases. 
     In addition, it is desirable that, in the gap between the substrate holding portion  20  and the tray portion  12 , the outermost position  602  in the non-contact sealing member  60  is separated from the surface side (the side where a wafer W is put on) of the substrate holding portion  20 . When the position  602  is near to the surface of the substrate holding portion  20 , the raw-material gas GS1 is likely to enter from the front side of the substrate holding portion  20 . It is desirable that the position  602  is separated from the surface of the substrate holding portion  20  in order to enhance the sealing effect of the raw-material gas GS1. For example, the position  602  is provided on the side of the tray portion  12  than the position  601 . 
     When vapor phase growth is performed by the vapor phase growth apparatus  120 , the raw-material gas GS1 is sent into the front side of the substrate holding portion  20 . Then, a wafer W is put on the substrate holding portion  20 , and the susceptor  10  and the substrate holding portion  20  are rotated. The rotation of the substrate holding portion  20  generates a labyrinth effect in the non-contact sealing member  60 . The labyrinth effect inhibits the raw-material gas GS1 from flowing into the housing  35 . 
       FIG. 6A  and  FIG. 6B  are schematic cross-sectional views illustrating a configuration of other non-contact sealing members. In a non-contact sealing member  60 A shown in  FIG. 6A , the second portion  62  extends diagonally downward. That is, the first portion  61  extends upward from the position  601  of the housing  35 . The second portion  62  goes diagonally downward from the uppermost position of the first portion  61  and then extends linearly to the position  602 . 
     In a non-contact sealing member  60 B shown in  FIG. 6B , the position  601  in the gap in communication with the housing  35  is provided on the underside of the housing  35 . In the non-contact sealing member  60 , the first portion  61  goes upward from the position  601  on the underside of the housing  35  and extends to the upper position than the housing  35 . The second portion  62  extends downward from the uppermost position of the first portion  61 . 
     Note that the configuration of the non-contact sealing member  60  is not limited to the examples shown in  FIG. 5A  to  FIG. 6B . 
     In the vapor phase growth apparatus  120  according to the present embodiment, such a sealing effect by the non-contact sealing member  60  can inhibit the raw-material gas GS1 from flowing into the housing  35  of the bearing  30 , thus, inhibiting deposit due to the raw-material gas GS1 from adhering to the surface of the bearing  30 . 
     Third Embodiment 
     Next, a vapor phase growth method according to a third embodiment will be described.  FIG. 7  is a flowchart illustrating the vapor phase growth method according to the third embodiment. The vapor phase growth method according to the present embodiment performs vapor phase growth using the vapor phase growth apparatuses  110  and  120  described above. 
     As shown in  FIG. 7 , the vapor phase growth method according to the present embodiment includes holding a wafer (step S 101 ), rotating a susceptor and a substrate holding portion (step S 102 ), introducing raw-material gas (step S 103 ) and forming a film (step S 104 ). 
     In step S 101 , the wafer W is put on the substrate holding portion  20  on the susceptor  10 . As the wafer W, a GaN substrate, a sapphire substrate, a SiC substrate, a GaAs substrate and an Si substrate may be used. 
     Next, in step S 102 , the susceptor  10  is rotated and the substrate holding portion  20  is also rotated. The substrate holding portion  20  revolves caused by the rotation of the susceptor  10 , and rotates on its axis with respect to the susceptor  10 . The wafer W also revolves and rotates on the axis thereof caused by the revolution and rotation of the substrate holding portion  20 . Next, while the susceptor  10  and the substrate holding portion  20  are being rotated, the wafer W is heated by the heater  50 . The heating temperature is between 600 degrees Celsius and 1,300 degrees Celsius, for example. 
     Next, in step S 103 , raw-material gas GS1 is introduced in the chamber  1 . As gas GS1 for growth, for example, organic metal gas is used. As the raw-material gas GS1, trimethyl gallium (TMGa), trimethyl indium (TMI), aluminum trimethyl (TMA), silane (SiH 4 ), arsine (AsH 3 ), phosphine (PH 3 ), ammoniacal (NH 3 ) and the like are used. Note that N 2  and H 2  are used for carrier gas, for example. 
     For example, when semiconductor devices such as a Light Emitting Diode (LED), a Laser Diode (LD) and an HEMT are manufactured, TMI, TMG, TMA, SiH 4  and NH 3  are used to perform vapor phase growth of the GaN-based film, and TMI, TMG, TMA, SiH 4 , AsH 3  and PH 3  are used to perform vapor phase growth of the GaAs-based film. 
     Further, in step S 103 , the counter gas GS2 may be introduced in addition to the introduction of the gas GS1 for growth. Inert gas such as N 2  is used for the counter gas GS2. 
     Next, in step S 104 , a film is formed on the surface of the wafer W in the chamber  1 . That is, the raw-material gas GS1 introduced in the chamber  1  reacts on the surface of the wafer W to achieve the crystal growth of the film according to the material of the raw-material gas GS1 on the surface of the wafer W. 
     When the vapor phase growth apparatus  110  is used in the vapor phase growth method according to the present embodiment, by the rotation of the blade portions  40  caused by the rotation of the substrate holding portion  20 , the pressure on the side of the housing  35  centered on the substrate holding portion  20  becomes higher than the pressure on the opposite side to the housing  35 . This inhibits the raw-material gas GS1 from entering into the housing  35  during film formation, and also inhibits the counter-flow of the counter gas GS2. 
     When the vapor phase growth apparatus  120  is used in the vapor phase growth method according to the present embodiment, for example, pressure difference due to a labyrinth effect is generated between the inside of the housing  35  and the outside of the housing  35  by the rotation of the substrate holding portion  20 . This inhibits the raw-material gas GS1 from entering into the housing  35  during film formation. 
     Using such a vapor phase growth method, the semiconductor devices including a light emitting device such as an LED, an HEMT and a power transistor are manufactured. 
     The vapor phase growth method according to the present embodiment effectively inhibits the raw-material gas GS1 from entering into the housing  35  of the bearing  30 . This inhibits deposit due to the raw-material gas GS1 from adhering to the surface of the bearing  30 . That is, inhibiting deposit from adhering to the surface of the bearing  30  reduces the interruption and stopping of the operation of the apparatus caused by the trouble of the bearing  30 . Thus, semiconductor devices having high quality can be manufactured productively. 
     As described above, according to the vapor phase growth apparatus and the vapor phase growth method according to the embodiments, the function of the bearing  30  that supports the substrate holding portion  20  can be maintained for a long time. 
     Note that although the present embodiment and variations thereof have been described, the present disclosure is not limited to these exemplary embodiments. For example, an MOCVD is taken as an example for the vapor phase growth apparatuses  110  and  120 , but a CVD other than an MOCVD can be applicable. In addition, addition, deletion and change of a configuration may be suitably made by those skilled in the art on each embodiment and variation described above, and features of each embodiment may be suitably combined, which are encompassed in the present disclosure, without departing from the spirit of the disclosure. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.