JP2012248818A - Vapor phase growth apparatus and vapor phase growth method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vapor phase growth apparatus and a vapor phase growth method for depositing a film on a substrate with uniform thickness.SOLUTION: An MOCVD apparatus 10 comprises a susceptor 21 having a top face 21a placed in a processing chamber 12 and rotating at a speed of 800 rpm or higher, and a shower head 31 having a plurality of gas discharge ports 44, 49 at positions facing the top face 21a of the susceptor 21 and supplying a material gas to the processing chamber 12 through the plurality of gas discharge ports 44, 49. A recess 22 in which a substrate 90 is placed is formed in the top face 21a of the susceptor 21. The substrate is placed so that a clearance is formed between the substrate and the inner wall of the recess 22, and a vapor phase growth face of the substrate is located at a position higher than the top face 21a of the susceptor 21.

Description

  The present invention generally relates to a vapor phase growth apparatus and a vapor phase growth method, and more specifically, a vapor phase growth apparatus in which a base for installing a substrate rotates at high speed, and such an apparatus. The present invention relates to the vapor phase growth method used.

  Regarding a conventional vapor phase growth apparatus, for example, Japanese Patent Application Laid-Open No. 11-54437 discloses a method for forming a compound semiconductor film for the purpose of preventing a decrease in luminance intensity of a light emitting element formed in the vicinity of an edge of a substrate. (Patent Document 1). In the method for forming a compound semiconductor film disclosed in Patent Document 1, a recess for installing a substrate on a susceptor is formed. In the recess, a stepped portion is provided such that the side wall portion side of the recess becomes higher, or the bottom surface of the recess is formed in a mortar shape.

  Japanese Patent Application Laid-Open No. 2007-214344 discloses a method for forming a compound semiconductor film for the purpose of preventing local heating caused by a substrate being warped downward (Patent Document 2). In the compound semiconductor film forming method disclosed in Patent Document 2, a recess is formed on the upper surface of the susceptor. The concave portion is formed so that the center of the substrate is always in non-contact with the susceptor and the outer peripheral portion of the substrate is always in contact with the susceptor, corresponding to the downward warping of the substrate.

  Japanese Patent Application Laid-Open No. 2010-126696 discloses that a plurality of nitride-based compound semiconductor elements having a high proportion of non-defective products are produced from a single semiconductor substrate while suppressing variations in the oscillation wavelength of the nitride-based compound semiconductor elements to be manufactured. A vapor phase growth apparatus for this purpose is disclosed (Patent Document 3). The vapor phase growth apparatus disclosed in Patent Document 3 has a substrate holder for holding a semiconductor substrate. The surface of the substrate holder that faces the semiconductor substrate is formed in substantially the same shape as the warpage of the semiconductor substrate.

Japanese Patent Laid-Open No. 11-54437 JP 2007-214344 A JP 2010-1226796 A

An MOCVD (Metal Organic Chemical Vapor Deposition) method is used for manufacturing a light emitting diode or a semiconductor laser. In this MOCVD method, for example, an organometallic gas such as trimethylgallium (TMG) or trimethylaluminum (TMA) and a hydrogen compound gas such as ammonia (NH ₃ ), phosphine (PH ₃ ), or arsine (AsH ₃ ) are formed. A compound semiconductor crystal is grown on the substrate by introducing it into the growth chamber as a source gas that contributes to the film.

  Thus, the MOCVD method is a method in which a source semiconductor gas is introduced into a growth chamber together with an inert gas such as hydrogen or nitrogen and heated to cause a gas phase reaction on the substrate, thereby growing a compound semiconductor crystal on the substrate. is there. In the manufacture of a compound semiconductor crystal using the MOCVD method, it is simultaneously required to improve the quality of the compound semiconductor crystal to be grown, to suppress the cost, to increase the yield, and to increase the production capacity.

  Patent Documents 1 to 3 described above disclose a vapor phase growth apparatus for forming a film on a substrate using the MOCVD method. For example, the susceptor disclosed in Patent Document 1 has a recess for installing the substrate. When the source gas is supplied onto the susceptor while rotating the susceptor, the source gas flows from the inner peripheral side to the outer peripheral side of the susceptor. During this time, the source gas that has passed over the substrate contributes to the film formation, so that the compound semiconductor film is deposited on the vapor phase growth surface of the substrate.

  However, the concave portion is formed in a shape larger than the substrate in order to enable setting of the substrate, and a gap is generated between the inner wall of the concave portion and the substrate. While the raw material gas passes through the gap, the consumption of the raw material gas due to the film formation is reduced. Therefore, at the end of the substrate positioned upstream of the raw material gas flow (upstream end of the substrate) Concentration increases. As a result, the film thickness of the compound semiconductor film formed on the substrate locally increases at the upstream end, and there is a concern that the compound semiconductor film cannot be formed with a uniform film thickness on the substrate.

  In the film forming process using the MOCVD method, the susceptor may be rotated at a high speed of 800 rpm or more for the purpose of improving the utilization efficiency of the source gas or improving the uniformity of the film thickness. In this case, as compared with the case where the susceptor rotates at a low speed, the source gas is less likely to diffuse into the gap between the inner wall of the recess and the substrate, and the consumption of the source gas due to film formation is particularly small. For this reason, the said concern that the film thickness of a compound semiconductor film becomes large locally in an upstream edge part becomes remarkable especially.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a vapor phase growth apparatus and a vapor phase growth method for forming a film with a uniform film thickness on a substrate.

  A vapor phase growth apparatus according to the present invention is a vapor phase growth apparatus for forming a film on a vapor phase growth surface of a substrate by supplying a source gas to a processing chamber in which the substrate is installed. The vapor phase growth apparatus has a top surface disposed in a processing chamber, a base that rotates at a speed of 800 rpm or more, a plurality of gas discharge ports at positions facing the top surface of the base, and a plurality of gas A gas supply unit that supplies a source gas to the processing chamber through the discharge port. The base is formed with a recess that is recessed from the top surface and on which the substrate is placed. The substrate is disposed such that a gap is formed between the substrate and the inner wall of the recess, and the vapor phase growth surface of the substrate is disposed at a position higher than the top surface of the base.

  According to the vapor phase growth apparatus configured as described above, since the vapor phase growth surface of the substrate is arranged at a position higher than the top surface of the base, the base is supplied from the plurality of gas discharge ports to the processing chamber. The source gas flowing on the top surface of the substrate collides with the side portion of the substrate before passing through the gap between the substrate and the inner wall of the recess and reaching the vapor phase growth surface. Thereby, the phenomenon that the concentration of the source gas is increased at the upstream end of the substrate can be suppressed, and a film can be formed with a uniform film thickness on the substrate.

  Preferably, when the diameter of the recess is D and the diameter of the substrate is d, the recess is formed so as to satisfy the relationship d <D ≦ d + 10 mm.

  According to the vapor phase growth apparatus configured as described above, the gap between the substrate and the inner wall of the recess is set to a width satisfying the relationship of d <D ≦ d + 10 mm. The phenomenon that the concentration of the raw material gas rises when passing through the gap can be suppressed. Thereby, the density | concentration of the source gas in the upstream edge part of a board | substrate can be controlled appropriately.

  Preferably, the source gas supplied by the gas supply unit does not contain nitrogen as a carrier gas. According to the vapor phase growth apparatus configured as described above, it is possible to form a film with a more uniform film thickness on the substrate.

  The vapor phase growth method according to the present invention is a vapor phase growth method for forming a film on a vapor phase growth surface of a substrate by supplying a source gas to a processing chamber in which the substrate is installed. The vapor phase growth method includes a step of placing a substrate on a base having a top surface disposed in a processing chamber, and the base is rotated at a speed of 800 rpm or more, and a source gas is introduced into the processing chamber from a position facing the top surface. And a supplying step. The base is formed with a recess that is recessed from the top surface and on which the substrate is placed. In the step of installing the substrate, the substrate is installed on the base so that a gap is formed between the substrate and the inner wall of the recess, and the vapor phase growth surface of the substrate is positioned higher than the top surface. Process.

  According to the vapor phase growth method configured in this way, a plurality of gases are used to place the substrate on the base so that the vapor phase growth surface of the substrate is positioned higher than the top surface of the base. Before the source gas supplied to the processing chamber from the discharge port and flowing on the top surface of the base passes through the gap between the substrate and the inner wall of the recess and reaches the vapor phase growth surface, Consumed and consumed. Thereby, the phenomenon that the concentration of the source gas is increased at the upstream end of the substrate can be suppressed, and a film can be formed with a uniform film thickness on the substrate.

  As described above, according to the present invention, it is possible to provide a vapor phase growth apparatus and a vapor phase growth method for forming a film with a uniform thickness on a substrate.

It is sectional drawing which shows the MOCVD (Metal Organic Chemical Vapor Deposition) apparatus in embodiment of this invention. It is a bottom view which shows the plate which comprises the shower head in FIG. It is a top view which shows the susceptor in FIG. It is sectional drawing which shows the susceptor in FIG. It is a figure which shows the cross section of a susceptor in the MOCVD apparatus for a comparison. It is a figure which shows the cross section of the susceptor in which the board | substrate was mounted in the MOCVD apparatus for a comparison. It is another figure which shows the cross section of the susceptor in which the board | substrate was mounted in the MOCVD apparatus for a comparison. It is a figure which shows the cross section of the susceptor in which the board | substrate was mounted in the MOCVD apparatus in embodiment of this invention. FIG. 11 is still another view showing a cross section of a susceptor on which a substrate is placed in a comparative MOCVD apparatus. In 1st Example, it is a graph which shows the relationship between the distance X from the upstream edge part of a board | substrate, and the film thickness of a compound semiconductor film. In 2nd Example, it is a graph which shows the relationship between the distance X from the upstream edge part of a board | substrate, and the film thickness of a compound semiconductor film. In 2nd Example, it is a graph which shows the relationship between the magnitude | size of the clearance gap between a board | substrate and a recessed part, and the thickness of the compound semiconductor film in the upstream edge part of a board | substrate.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are denoted by the same reference numerals.

  FIG. 1 is a cross-sectional view showing a MOCVD (Metal Organic Chemical Vapor Deposition) apparatus according to an embodiment of the present invention.

  Referring to FIG. 1, an MOCVD apparatus 10 is an apparatus for forming a compound semiconductor film on a substrate using MOCVD. The MOCVD apparatus 10 includes a reaction furnace 11, a shower head 31, a group III-based gas supply source 41, a group V-based gas supply source 46, a mass flow controller 42 and a mass flow controller 47, and a cooling device 51.

  The reaction furnace 11 forms a processing chamber 12 for growing a compound semiconductor crystal on a vapor phase growth surface of a substrate as a processing target. The processing chamber 12 is formed by a hollow portion inside the reaction furnace 11.

  The shower head 31 is provided as a gas supply unit for supplying a source gas contributing to film formation to the processing chamber 12. The shower head 31 is connected to the reaction furnace 11. The shower head 31 is disposed on the ceiling of the reaction furnace 11. The shower head 31 includes a gas introduction part 32, a water cooling part 33 as a cooling part, and a plate 34 as a gas discharge port forming part.

  The group III-based gas supply source 41 is provided as a source of a group III-based gas containing a group III element, and the group V-based gas supply source 46 is provided as a source of a group V-based gas containing a group V element. Yes. The group III gas supply source 41 is connected to the gas introduction part 32 via a group III gas pipe 43, and the group V gas supply source 46 is connected to the gas introduction part 32 via a group V gas pipe 48. Has been.

  A mass flow controller serving as a group III gas introduction amount adjusting unit on the pipe line of the group III gas piping 43 that allows the amount of group III gas introduced from the group III gas supply source 41 to the gas introduction unit 32 to be adjusted. 42 is provided. A mass flow controller as a group V gas introduction amount adjusting unit that allows the amount of group V gas introduced from the group V gas supply source 46 to the gas introduction unit 32 to be adjusted on the pipe of the group V gas pipe 48. 47 is provided.

Examples of the group III element include Ga (gallium), Al (aluminum), and In (indium). Examples of the group III gas containing the group III element include trimethylgallium (TMG) and trimethylaluminum (TMA). One or more kinds of organometallic gases such as are used. Examples of the group V element include N (nitrogen), P (phosphorus), and As (arsenic), and examples of the group V gas containing the group V element include ammonia (NH ₃ ) and phosphine (PH ₃ ) or one or more hydrogen compound gases such as arsine (AsH ₃ ) are used.

  The cooling device 51 is connected to the water cooling unit 33 via a water cooling system pipe 52. Cooling water is supplied to the water cooling unit 33 from the cooling device 51 through the water cooling system pipe 52. The cooling water supplied to the water cooling unit 33 cools the raw material gas introduced into the gas introduction unit 32 and prevents the raw material gas from reaching a high temperature. Thereby, it is possible to prevent the raw material gas from reacting in the shower head 31 to generate a reaction product, and the reaction product to prevent a gas discharge port 44 and a gas discharge port 49 described later from being blocked.

  FIG. 2 is a bottom view showing a plate constituting the shower head in FIG. With reference to FIGS. 1 and 2, the plate 34 is disposed in the processing chamber 12. The plate 34 is provided at the bottom of the shower head 31.

  A plurality of gas discharge ports 44 and a plurality of gas discharge ports 49 are formed in the plate 34. The gas discharge port 44 and the gas discharge port 49 are open to the processing chamber 12.

  The group III gas introduced from the group III gas supply source 41 into the gas introduction unit 32 is supplied to the processing chamber 12 through the plurality of gas discharge ports 44 and introduced from the group V gas supply source 46 into the gas introduction unit 32. The group V gas thus supplied is supplied to the processing chamber 12 through a plurality of gas discharge ports 49. The plurality of gas discharge ports 44 and the plurality of gas discharge ports 49 are arranged in a plane on the bottom surface of the plate 34 so that the group III-based gas and the group V-based gas are uniformly supplied to the processing chamber 12. ing. The plurality of gas discharge ports 44 and the plurality of gas discharge ports 49 are opened at positions facing a top surface 21a of the susceptor 21 described later.

  In FIG. 2, the gas discharge port 44 is hatched in order to distinguish the gas discharge port 44 and the gas discharge port 49 from each other.

  FIG. 3 is a plan view showing the susceptor in FIG. 1 to 3, the MOCVD apparatus 10 further includes a susceptor 21, a rotating shaft 13, a heater 15, and a cover plate (heater cover) 58.

  The susceptor 21 is provided as a base for supporting the substrate 90 that is a processing target in the processing chamber 12. The susceptor 21 is disposed to face the plate 34. The susceptor 21 has a disk shape centered on the center line 101 shown as a virtual line in the drawing. The susceptor 21 is made of a conductive material such as carbon.

  The susceptor 21 has a top surface 21a. The top surface 21 a is disposed in the processing chamber 12. The top surface 21 a faces the plate 34. The top surface 21 a faces a plurality of gas discharge ports 44 and a plurality of gas discharge ports 49 that open in the plate 34. The top surface 21a extends in parallel with the bottom surface of the plate 34 in which the plurality of gas discharge ports 44 and the plurality of gas discharge ports 49 are opened. The top surface 21 a extends in a plane orthogonal to the direction in which the source gas is discharged from the gas discharge port 44 and the gas discharge port 49.

  The heater 15 is provided as a heating unit for heating the substrate supported by the susceptor 21. The susceptor 21 is installed on the heater 15. The heater 15 is disposed on the opposite side of the shower head 31 with respect to the susceptor 21.

  The rotating shaft 13 extends along the center line 101 and is connected to the susceptor 21. The rotating shaft 13 is rotatably provided by an actuator (not shown). As the rotary shaft 13 rotates, the susceptor 21 rotates about the center line 101 in the direction indicated by the arrow 110 in FIG. The susceptor 21 rotates while maintaining a posture in which the top surface 21 a faces the plate 34.

  In MOCVD apparatus 10 in the present embodiment, susceptor 21 rotates at a speed of 800 rpm or higher. By rotating the susceptor 21 at a high speed, the source gas is attracted to the substrate 90 by the shear flow generated during the high-speed rotation, so that the ratio of the source gas contributing to the film formation is improved. Further, since the uniformity of the thickness of the boundary layer generated on the film formation surface of the substrate 90 is increased, the uniformity of the film thickness that is inversely proportional to the thickness of the boundary layer is improved.

  The covering plate 58 is provided so as to surround the susceptor 21, the rotating shaft 13, and the heater 15 on the outer periphery centered on the center line 101.

  The MOCVD apparatus 10 further includes a gas exhaust unit 57 and a gas processing device 56. The gas exhaust part 57 is provided to exhaust the source gas inside the processing chamber 12 to the outside. The gas exhaust part 57 is connected to the reaction furnace 11. The gas exhaust part 57 communicates with the processing chamber 12 at a position on the outer peripheral side of the susceptor 21 and farther from the top surface 21a of the susceptor 21 when viewed from the shower head 31 side.

  The gas processing device 56 is connected to the gas exhaust unit 57 via the purge line 55. The gas processing device 56 performs a process for rendering the source gas sent from the gas exhaust part 57 through the purge line 55 harmless.

  FIG. 4 is a cross-sectional view showing the susceptor in FIG. With reference to FIGS. 1 to 4, a recess 22 is formed in the susceptor 21. In the present embodiment, a plurality of recesses 22 are formed in the susceptor 21.

  The concave portion 22 is formed in a concave shape that is recessed from the top surface 21a. The concave portion 22 is disposed so as to be shifted radially outward from the center line 101. The plurality of recesses 22 are arranged at intervals from each other in the circumferential direction around the center line 101. The plurality of recesses 22 are arranged at equal intervals in the circumferential direction around the center line 101. In the present embodiment, the four concave portions 22 are arranged at intervals of 90 °. The substrate 90 that is the object to be processed is placed in the recess 22.

  When the top surface 21 a is viewed from the front, the recess 22 has a circular shape corresponding to the substrate 90. The recess 22 has a shape larger than that of the substrate 90 so that the substrate 90 can be placed in the recess 22 (the diameter d of the substrate 90 <the diameter D of the recess 22). For example, the diameter of the recess 22 is set to 105 mm for the substrate 90 having a diameter of 100 mm. The substrate 90 is placed at a substantially central position of the recess 22. A gap 61 is formed between the inner wall of the recess 22 and the substrate 90 in a state where the substrate 90 is placed in the recess 22.

  The substrate 90 has a vapor phase growth surface 90 a on which a compound semiconductor crystal is grown in the processing chamber 12. The substrate 90 is placed in the recess 22 so that the vapor phase growth surface 90a and the plate 34 face each other. The vapor phase growth surface 90 a extends in parallel with the top surface 21 a of the susceptor 21. In the MOCVD apparatus 10 according to the present embodiment, the substrate 90 is installed in the recess 22 so that the vapor phase growth surface 90 a is disposed at a position higher than the top surface 21 a of the susceptor 21. That is, when the height of the substrate 90 is h and the depth of the recess 22 is H, the substrate 90 is disposed in the recess 22 so as to satisfy the relationship of h> H.

  As an example, the depth of the recess 22 is determined so that the vapor phase growth surface 90a is disposed at a position 0.2 mm higher than the top surface 21a of the susceptor 21. In the present embodiment, the difference in height between the vapor phase growth surface 90 a and the recess 22 is smaller than the depth of the recess 22.

  The vapor phase growth method for forming a film on the substrate 90 using the MOCVD apparatus 10 will be described. First, the substrate 90 is placed in the recess 22 of the susceptor 21. At this time, a gap 61 is formed between the substrate 90 and the inner wall of the recess 22, and the vapor phase growth surface 90 a of the substrate 90 is disposed at a position higher than the top surface 21 a of the susceptor 21. Is placed in the recess 22. Next, the heater 15 is heated to heat the substrate 90 to a predetermined temperature via the susceptor 21 and the susceptor 21 is rotated about the center line 101 at a speed of 800 rpm or more.

  Group III-based gas and Group V-based gas are supplied to the processing chamber 12 from a gas discharge port 44 and a gas discharge port 49, respectively. At this time, the introduction amounts of the group III-based gas and the group V-based gas are respectively controlled by the mass flow controller 42 and the mass flow controller 47 that receive signals from a control unit (not shown).

  The source gas supplied to the processing chamber 12 flows in a direction perpendicular to the top surface 21 a of the susceptor 21, and then centered on the center line 101 from a position on the top surface 21 a facing each gas discharge port 44, 49. To flow radially outward. While the source gas passes over the heated substrate 90, a group III-V compound semiconductor crystal grows on the vapor phase growth surface 90 a of the substrate 90.

  Next, the operation and effect exhibited by the MOCVD apparatus 10 and the vapor phase growth method using the MOCVD apparatus 10 in the present embodiment will be described.

  FIG. 5 is a view showing a cross section of a susceptor in an MOCVD apparatus for comparison. FIG. 6 is a view showing a cross section of a susceptor on which a substrate is placed in a comparative MOCVD apparatus. In the drawing, a graph showing changes in the concentration of the source gas and the film thickness of the compound semiconductor film corresponding to each cross-sectional position is shown.

  5 and 6, in this comparative example, the vapor phase growth surface 90a and the top surface 21a of the susceptor 21 are arranged at the same height.

  As shown in FIG. 5, while the source gas flows on the susceptor 21 outward in the radial direction centered on the center line 101, a part of the source gas contributes to the film formation, while each gas discharge port 44. , 49, a new source gas is added to the flow on the susceptor 21. For this reason, film formation is performed on the top surface 21a of the susceptor 21 with a constant film thickness while the concentration of the source gas is kept constant at each position on the susceptor 21.

  As shown in FIG. 6, a gap 61 is formed between the substrate 90 and the inner wall of the recess 22. While the raw material gas passes through the gap 61, the amount of the raw material gas consumed by the film formation is reduced, so that the concentration of the raw material gas is the end of the substrate 90 positioned upstream of the raw material gas flow (upstream of the substrate 90). It becomes higher at the side edge). In this case, a phenomenon occurs in which the film thickness locally increases at the upstream end of the substrate 90 formed by the high-concentration source gas.

  FIG. 7 is another view showing a cross section of a susceptor on which a substrate is placed in a comparative MOCVD apparatus. In the drawing, the change in the concentration of the source gas when the susceptor 21 rotates at a high speed is indicated by a line 126 corresponding to each cross-sectional position, and the change in the concentration of the source gas when the susceptor 21 rotates at a low speed is indicated by a line 127. Indicated by.

  Referring to FIG. 7, the susceptor 21 rotates at a high speed of 800 rpm or higher (curve 121 described in the gap 61), and the susceptor 21 rotates at a low speed (curve 122 described in the gap 61). Thus, the source gas diffuses only to a shallow range of the gap 61 while moving from the top surface 21a to the vapor phase growth surface 90a, and as a result, the amount of the source gas reaching the vapor phase growth surface 90a increases. . Since the concentration of the source gas and the film thickness are in a proportional relationship, the phenomenon that the film thickness increases locally at the upstream end of the substrate 90 is particularly noticeable when the susceptor 21 rotates at a high speed of 800 rpm or higher. Become.

  FIG. 8 is a view showing a cross section of the susceptor on which the substrate is placed in the MOCVD apparatus according to the embodiment of the present invention. In the drawing, a graph showing changes in the concentration of the source gas and the film thickness of the compound semiconductor film corresponding to each cross-sectional position is shown.

  Referring to FIG. 8, in contrast, in MOCVD apparatus 10 in the present embodiment, vapor phase growth surface 90 a of substrate 90 is arranged at a position higher than top surface 21 a of susceptor 21. According to such a configuration, the source gas flowing on the susceptor 21 is partially consumed by colliding with the side surface 90b of the substrate 90 before reaching the vapor phase growth surface 90a. Thereby, the concentration of the source gas reaching the vapor phase growth surface 90a can be appropriately controlled, and the phenomenon that the film thickness locally increases at the upstream end portion of the substrate 90 can be avoided.

  FIG. 9 is still another view showing a cross section of a susceptor on which a substrate is placed in a comparative MOCVD apparatus. In the drawing, the change in the concentration of the raw material gas when the width of the gap between the substrate and the recess is small is shown by a line 141 corresponding to each cross-sectional position, and the raw material when the width of the gap between the substrate and the recess is large The change in gas concentration is indicated by line 142.

  As shown in FIG. 9, when the width of the gap 61 between the inner wall of the concave portion 22 of the substrate 90 is large, the source gas concentration at the upstream end of the substrate 90 is smaller than when the width of the gap 61 is small. The rise of From the viewpoint of appropriately controlling the source gas concentration by collision between the source gas and the side surface 90b of the substrate 90 while suppressing an increase in the source gas concentration at the upstream end of the substrate 90, the inner walls of the substrate 90 and the recess 22 are used. Is preferably set to a width satisfying the relationship of d <D ≦ d + 10 mm (d: diameter of the substrate 90, D: diameter of the recess 22).

  The structure of the MOCVD apparatus 10 according to the embodiment of the present invention described above will be described together. The MOCVD apparatus 10 as the vapor phase growth apparatus according to the present embodiment has a raw material in the processing chamber 12 in which the substrate 90 is installed. By supplying a gas, a film is formed on the vapor phase growth surface 90 a of the substrate 90. The MOCVD apparatus 10 has a top surface 21 a disposed in the processing chamber 12, and a susceptor 21 as a base that rotates at a speed of 800 rpm or more, and a plurality of gas discharge ports 44 at positions facing the top surface 21 a of the susceptor 21. 49, and a shower head 31 as a gas supply unit for supplying the raw material gas to the processing chamber 12 through the plurality of gas discharge ports 44, 49. The susceptor 21 is formed with a recess 22 that is recessed from the top surface 21a and on which the substrate 90 is placed. The substrate 90 is disposed such that a gap 61 is formed between the substrate 90 and the inner wall of the recess 22, and the vapor phase growth surface 90 a of the substrate 90 is disposed at a position higher than the top surface 21 a of the susceptor 21. Is done.

  According to the MOCVD apparatus 10 according to the embodiment of the present invention configured as described above, the vapor phase growth surface 90a of the substrate 90 is disposed at a position higher than the top surface 21a of the susceptor 21, and therefore the upstream of the substrate 90. The phenomenon that the film thickness locally increases at the side end can be avoided. Thereby, the compound semiconductor film can be formed with a uniform film thickness on the substrate 90.

  Next, examples performed for confirming the above-described functions and effects achieved by the MOCVD apparatus 10 in the present embodiment will be described.

  FIG. 10 is a graph showing the relationship between the distance X from the upstream end of the substrate and the film thickness of the compound semiconductor film in the first embodiment.

  Referring to FIG. 10, in this example, a group III-V compound semiconductor crystal was grown on the vapor phase growth surface 90 a of the substrate 90 using the MOCVD apparatus 10. At this time, the diameter d of the substrate 90 was set to 100 mm, the diameter D of the recess 22 was set to 105 mm, and the vapor phase growth surface 90 a of the substrate 90 was set 0.2 mm higher than the top surface 21 a of the susceptor 21. Regarding the growth conditions of the compound semiconductor film, the substrate temperature was 1100 ° C., the growth pressure was 100 Torr, the total flow rate of the source gas was 20 L / min, and the rotation speed of the susceptor 21 was 800 rpm. Hydrogen gas was used as a carrier gas for the source gas.

  After the film forming step, the film thickness of the compound semiconductor film formed on the substrate 90 is measured for each distance X (see FIG. 4) from the upstream end of the substrate 90, and the result is shown in FIG. It was shown to. The center of the substrate 90 is when X = 50 mm. For comparison, the vapor phase growth surface 90a of the substrate 90 is set to the same height as the top surface 21a of the susceptor 21, and the vapor phase growth surface 90a of the substrate 90 is 0.2 mm lower than the top surface 21a of the susceptor 21. In the case of setting, the same film formation process and measurement process were performed, and the results are shown in FIG.

  As can be seen from the results shown in FIG. 10, in the example in which the vapor phase growth surface 90a of the substrate 90 is set 0.2 mm higher than the top surface 21a of the susceptor 21, the substrate 90 is compared with the other two comparative examples. The film thickness of the compound semiconductor film at the upstream end of the film could be kept small.

  Further, as an additional example, the above-described film forming process and measurement process were performed when nitrogen gas was used as the carrier gas of the source gas. As a result, when hydrogen gas is used as the carrier gas and when nitrogen gas is used, when hydrogen gas is used (when nitrogen gas is not included as the carrier gas), the upstream end of the substrate 90 It was confirmed that the thickness of the compound semiconductor film in the portion was smaller.

  FIG. 11 is a graph showing the relationship between the distance X from the upstream end of the substrate and the film thickness of the compound semiconductor film in the second embodiment.

  Referring to FIG. 11, also in this example, the film forming process was performed on substrate 90 under the same growth conditions as in the first example. At this time, the diameter d of the substrate 90 is set to 100 mm, the vapor phase growth surface 90 a of the substrate 90 is set 0.2 mm higher than the top surface 21 a of the susceptor 21, and the diameter D of the recess 22 is set to 105 mm (B = (D− d) = 5 mm), 107.5 mm (B = 7.5 mm), 110 mm (B = 10 mm), 111 mm (B = 11 mm), and 112 mm (B = 12 mm).

  FIG. 12 is a graph showing the relationship between the size of the gap between the substrate and the recess and the thickness of the compound semiconductor film at the upstream end of the substrate in the second embodiment. After the film forming step, the thickness of the compound semiconductor film formed on the substrate 90 was measured for each distance X from the upstream end of the substrate 90, and the result is shown in FIG. FIG. 12 shows the thickness of the compound semiconductor film at the upstream end of the substrate when the difference B between the diameters of the substrate and the recesses is 5 mm, 7.5 mm, 10 mm, 11 mm, and 12 mm.

  As can be seen from the results shown in FIGS. 11 and 12, when B ≦ 10 mm, that is, when the gap 61 between the substrate 90 and the inner wall of the recess 22 is set to a width satisfying the relationship of D ≦ d + 10 mm, The thickness of the compound semiconductor film at the upstream end of the substrate could be further reduced.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention is applied to, for example, a vertical showerhead type MOCVD (Metal Organic Chemical Vapor Deposition) apparatus.

  DESCRIPTION OF SYMBOLS 10 MOCVD apparatus, 11 Reaction furnace, 12 Processing chamber, 13 Rotating shaft, 15 Heater, 21 Susceptor, 21a Top surface, 22 Recessed part, 31 Shower head, 32 Gas introduction part, 33 Water cooling part, 34 Plate, 41 III group gas Supply source, 42, 47 mass flow controller, 43 Group III gas piping, 44, 49 Gas outlet, 46 Group V gas supply source, 48 Group V gas piping, 51 Cooling device, 52 Water cooling system piping, 55 Purge line , 56 Gas processing device, 57 Gas exhaust part, 58 Cover plate, 61 Crevice, 90 Substrate, 90a Vapor growth surface, 90b Side surface.

Claims (4)

A vapor phase growth apparatus for forming a film on a vapor phase growth surface of a substrate by supplying a source gas to a processing chamber in which the substrate is installed,
A base having a top surface disposed in the processing chamber and rotating at a speed of 800 rpm or more;
A plurality of gas discharge ports at a position facing the top surface, and a gas supply unit that supplies a source gas to the processing chamber through the plurality of gas discharge ports,
The base is recessed from the top surface, and a recess is formed on which the substrate is placed.
The substrate is disposed such that a gap is formed between the substrate and the inner wall of the recess, and the vapor phase growth surface of the substrate is disposed at a position higher than the top surface.   2. The vapor phase growth apparatus according to claim 1, wherein when the diameter of the recess is D and the diameter of the substrate is d, the recess is formed so as to satisfy a relationship of d <D ≦ d + 10 mm.   3. The vapor phase growth apparatus according to claim 1, wherein the source gas supplied by the gas supply unit does not contain nitrogen as a carrier gas. A vapor phase growth method for forming a film on a vapor phase growth surface of a substrate by supplying a source gas to a processing chamber in which the substrate is installed,
Installing the substrate on a base having a top surface disposed in the processing chamber;
A step of rotating the base at a speed of 800 rpm or more and supplying a source gas to a processing chamber from a position facing the top surface;
The base is recessed from the top surface, and a recess is formed on which the substrate is placed.
The step of installing the substrate is performed on the base so that a gap is formed between the substrate and the inner wall of the recess, and the vapor phase growth surface of the substrate is disposed at a position higher than the top surface. A vapor phase growth method including a step of installing a substrate.

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