JP2019196292A - Vapor phase growth apparatus - Google Patents

Abstract

To provide a technique related to a vapor phase growth apparatus for compound semiconductor.SOLUTION: The vapor phase growth apparatus is arranged within the reaction container, and comprises a substrate holder having a substrate holding surface for holding a substrate on a first surface. The vapor phase growth apparatus comprises a ring part having a hole part corresponding to the substrate held on the substrate holding surface. The vapor phase growth apparatus comprises a raw material gas supply pipe which supplies a first raw material gas and a second raw material gas reacting with the first raw material gas into the reaction container. The first raw material gas and second raw material gas are raw material gases growing a crystal of a compound semiconductor on a surface of the substrate. The vapor phase growth apparatus comprises an actuator which moves at least one of the substrate holder and ring part along an axis perpendicular to the substrate holding surface. The actuator keeps constant the distance between a surface of the crystal of the compound semiconductor grown on the substrate and a surface of the ring part.SELECTED DRAWING: Figure 1

Description

  The present specification discloses a technique related to a vapor phase growth apparatus for a compound semiconductor.

  Construction of a low-cost manufacturing method for GaN substrates is required. The current GaN substrate is a single-wafer type that grows one by one, which is a cause of high cost. A related technique is disclosed in Patent Document 1.

JP 2002-316892 A

  If long crystal growth of GaN becomes possible, a plurality of wafers can be generated from one long crystal, and the substrate manufacturing cost can be reduced. However, it is difficult to grow long crystals of GaN. One factor is that cracks are generated when a long crystal is grown. This is because the end surface of the outer peripheral portion of the grown crystal is not perpendicular to the surface of the seed substrate, but becomes a tapered surface. When the taper surface takes in oxygen, the lattice constant decreases and stress is generated, so that the grown crystal cracks.

  The present specification discloses a vapor phase growth apparatus. This vapor phase growth apparatus includes a reaction vessel. The vapor phase growth apparatus is disposed in a reaction vessel and includes a substrate holder having a substrate holding surface for holding a substrate on a first surface. The vapor phase growth apparatus includes a ring portion having a hole corresponding to the substrate held on the substrate holding surface. The vapor phase growth apparatus includes a source gas supply pipe that supplies a first source gas and a second source gas that reacts with the first source gas into the reaction vessel. The first source gas and the second source gas are source gases for growing compound semiconductor crystals on the surface of the substrate. The vapor phase growth apparatus includes an actuator that moves at least one of the substrate holder and the ring portion along an axis perpendicular to the substrate holding surface. The actuator maintains a constant distance between the surface of the compound semiconductor crystal grown on the substrate and the surface of the ring portion.

  In the vapor phase growth apparatus of the present specification, the distance between the surface of the compound semiconductor crystal grown on the substrate and the surface of the ring portion can be kept constant by the actuator. Thereby, even when the crystal grows and becomes thicker, the flow of the first and second source gases in the outer peripheral portion of the substrate can be maintained constant. This makes it possible to obtain a homogeneous crystal even when the crystal becomes thick. Furthermore, by supporting the outer peripheral portion of the crystal with the inner wall surface of the ring portion, the end surface of the outer peripheral portion of the grown crystal can be made a plane perpendicular to the surface of the substrate. It is possible to prevent the occurrence of cracks in the grown crystal.

  The actuator may move the substrate holder to the second surface side opposite to the first surface. The moving speed of the substrate holder may be equal to the growth speed of the compound semiconductor crystal in the thickness direction.

  The actuator may maintain a state in which the distance from the substrate holding surface to the surface of the ring portion is larger by a predetermined distance than the distance from the substrate holding surface to the surface of the compound semiconductor crystal grown on the substrate.

  The surface of the ring portion may be covered with a predetermined metal capable of decomposing the second source gas by a catalytic effect.

  The predetermined metal may be a metal containing tungsten.

  The gas supply port of the source gas supply pipe may be arranged at a position facing the substrate holding surface. The actuator may move the substrate holder so that the distance between the surface of the compound semiconductor crystal growing on the substrate and the gas supply port is kept constant.

The first source gas may be a gas containing GaCl. The second source gas may be a gas containing NH ₃ .

It is the schematic sectional drawing which looked at the vapor phase growth apparatus concerning Example 1 from the side. It is the elements on larger scale of sectional drawing of a substrate holder, a ring plate, and a shower head. It is the figure which looked at the sectional view in the III-III line from the perpendicular lower part. It is the figure which looked at the sectional view in the IV-IV line from the perpendicular upper part. It is the elements on larger scale of sectional drawing of a substrate holder, a ring plate, and a shower head. It is the elements on larger scale of sectional drawing of a substrate holder, a ring plate, and a shower head. It is the elements on larger scale of sectional drawing of a substrate holder, a ring plate, and a shower head in a comparative example. It is the elements on larger scale of sectional drawing of a substrate holder, a ring plate, and a shower head in a comparative example. It is the schematic sectional drawing which looked at the vapor phase growth apparatus concerning Example 2 from the side. It is the schematic sectional drawing which looked at the vapor phase growth apparatus concerning Example 3 from the side.

<Configuration of vapor phase growth apparatus>
FIG. 1 shows a schematic cross-sectional view of a vapor phase growth apparatus 1 according to the technique of this specification as viewed from the side. The vapor phase growth apparatus 1 is an example of an apparatus configuration for carrying out a HVPE (Halide Vapor Phase Epitaxy) method. The vapor phase growth apparatus 1 includes a reaction vessel 10. The reaction vessel 10 has a cylindrical shape. The reaction vessel 10 may be made of quartz. A source gas supply unit 20 and a substrate holder 11 are disposed inside the reaction vessel 10.

  In FIG. 2, the elements on larger scale of the sectional view of the substrate holder 11, the ring plate 12, and the shower head 50 are shown. The substrate holder 11 includes a holder main body 11b and a support portion 11c. A substrate holding surface 11 a is provided on the lower surface of the substrate holder 11. The support part 11c of the substrate holder 11 holds the substrate 13 so that the surface of the substrate 13 is substantially vertically downward. Note that “substantially vertically downward” is not limited to an aspect in which the normal line of the substrate coincides with the vertically downward direction. This is a concept including a normal of the substrate including an inclination of up to 45 degrees with respect to the vertical downward direction. The substrate 13 is a seed substrate for growing a GaN single crystal, and is a single crystal of GaN. The surface of the substrate 13 is a + c plane (also referred to as a (0001) plane).

The surface of the support portion 11 c is covered with a predetermined metal 17. The predetermined metal 17 is a metal that can decompose the second source gas G2 by a catalytic effect. In the present embodiment, a material containing tungsten is used as the predetermined metal 17. Thereby, the effect which suppresses precipitation of the GaN polycrystal on the surface of the support part 11c is acquired. This is because the active hydrogen generated when NH ₃ is decomposed by the catalytic effect suppresses the precipitation of GaN polycrystals.

  A ring plate 12 is disposed below the substrate holder 11. The surface of the ring plate 12 is covered with a predetermined metal 18. The predetermined metal 18 is a metal that can decompose the second source gas G2 by a catalytic effect. In the present embodiment, a material containing tungsten is used as the predetermined metal 18. Thereby, the effect which suppresses precipitation of the GaN polycrystal on the surface of the ring plate 12 is acquired.

  The lower surface 12a of the ring plate 12 is a surface corresponding to the substrate holding surface 11a. In this embodiment, the lower surface 12a is a plane parallel to the substrate holding surface 11a. The ring plate 12 includes a hole 12b corresponding to the substrate 13 held on the substrate holding surface 11a. Here, the central axis of the substrate holder 11 is A1. The position of the inner wall 11cw of the support portion 11c is defined as a position P1. The position of the inner wall 12w that forms the hole 12b of the ring plate 12 is defined as a position P2. The distance D2 from the central axis A1 to the position P2 may be greater than or equal to the distance D1 from the central axis A1 to the position P1.

  FIG. 3 shows a cross-sectional view taken along line III-III in FIG. As shown in FIG. 3, the ring plate 12 is a ring-shaped member. As described above, when the distance D2 is equal to or greater than the distance D1, the entire exposed surface of the substrate 13 is included in the range of the hole 12b of the ring plate 12.

  The lower end of the rotating shaft 14 is connected to the upper part of the substrate holder 11. The upper end part of the rotating shaft 14 protrudes outside the reaction vessel 10 (see FIG. 1). The upper end of the rotating shaft 14 is connected to the actuator 15. As a result, the substrate holder 11 moves upward (direction on the upper surface 11d side of the substrate holder 11) and downward (direction on the substrate holding surface 11a side of the substrate holder 11) along the central axis A1 perpendicular to the substrate holding surface 11a. ). In addition, the substrate holder 11 can be rotated by the actuator 15.

The structure of the source gas supply unit 20 will be described. The source gas supply unit 20 is a cylindrical member. The source gas supply unit 20 includes a cylindrical cover 24. A disc-shaped shower head 50 is disposed at the upper end of the cover 24. In the lower part of the source gas supply unit 20, an inlet of the HCl gas supply pipe 25 and an inlet of the second source gas supply pipe 22 are arranged. A first valve 61 is disposed at the inlet of the HCl gas supply pipe 25. The first valve 61 controls the supply of gas containing HCl. The outlet of the HCl gas supply pipe 25 is connected to the first source gas generation unit 41. The first source gas generation unit 41 stores metal gallium inside. The first source gas generation unit 41 is a part that generates a first source gas G1 containing GaCl. The first source gas supply pipe 21 is a pipe that supplies the first source gas G1. The inlet of the first source gas supply pipe 21 is connected to the first source gas generator 41. The outlet of the first source gas supply pipe 21 is connected to the shower head 50. A second valve 62 is disposed at the inlet of the second source gas supply pipe 22. The second valve 62 controls the supply of gas containing the second source gas G2. The second source gas G2 is a gas containing NH ₃ . The outlet of the second source gas supply pipe 22 is connected to the shower head 50.

  The first source gas supply pipe 21 and the second source gas supply pipe 22 are arranged to extend in the vertical direction (that is, the z-axis direction in FIG. 1). A partition wall 42 is disposed on the path of the first source gas supply pipe 21 and the second source gas supply pipe 22. The partition wall 42 is a quartz plate that extends horizontally in the cover 24. The space in the cover 24 is separated up and down by a partition wall 42. The partition wall 42 functions as a heat insulating material.

  The shower head 50 is a part for discharging the first source gas G1 and the second source gas G2 to the vicinity of the surface of the substrate 13. The shower head 50 is disposed at a position facing the substrate holding surface 11 a of the substrate holder 11. The first source gas G1 and the second source gas G2 discharged from the shower head 50 flow vertically upward in the reaction container 10 in the direction of the arrow Y1.

  The structure of the shower head 50 will be described with reference to FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 1 as viewed from above. On the surface of the shower head 50, a plurality of first gas supply ports 51 for discharging the first source gas G1 and a plurality of second gas supply ports 52 for discharging the second source gas G2 are arranged. By discharging the first source gas G1 and the second source gas G2 from a large number of gas supply ports, the amount of gas supplied to the surface of the substrate 13 can be made uniform in the plane. Therefore, in-plane variation of the grown GaN crystal film thickness can be suppressed. A region where the first gas supply port 51 and the second gas supply port 52 are not formed on the surface of the shower head 50 is covered with a predetermined metal 53. In this embodiment, a material containing tungsten is used as the predetermined metal.

  Around the source gas supply unit 20, a gas exhaust pipe 23 for exhausting the gas in the reaction vessel 10 is configured. This will be described with reference to FIG. A cylindrical source gas supply unit 20 is further arranged inside the cylindrical reaction vessel 10. As a result, an annular gap is formed between the inner wall of the reaction vessel 10 and the outer wall of the cover 24 of the source gas supply unit 20. This annular gap functions as the gas exhaust pipe 23.

  Further, the inlet 23 a (see FIG. 1) of the gas exhaust pipe 23 can be positioned on the side surface of the shower head 50. Therefore, as shown by an arrow Y2 in FIG. 1, the first source gas G1 and the second source gas G2 used for the GaN crystal growth on the surface of the substrate 13 are exhausted in the lateral direction of the shower head 50 and downward of the substrate 13. Can be made. An outlet 23 b of the gas exhaust pipe 23 is disposed at the lower end of the reaction vessel 10. The gas sucked from the inlet 23a of the gas exhaust pipe 23 is discharged from the outlet 23b to the vent line.

  A specific gas supply pipe 16 is provided at the top of the reaction vessel 10. A specific gas G3 is supplied to the inlet of the specific gas supply pipe 16. As shown by an arrow Y3 in FIG. 1, the specific gas G3 flows from above the substrate holder 11 vertically downward and is sucked into the inlet 23a of the gas exhaust pipe 23. Thereby, a downflow can be generated by the specific gas G3. The specific gas G3 is a gas that does not contain oxygen and does not react with the first source gas G1 and the second source gas G2. As a specific example, the specific gas G3 is a gas containing at least one of hydrogen, nitrogen, helium, neon, argon, and krypton.

  An upper heater 31 and a lower heater 32 are disposed outside the reaction vessel 10. A partition wall 42 is disposed in the vicinity of the boundary between the region H1 where the upper heater 31 is disposed and the region H2 where the lower heater 32 is disposed. The upper heater 31 can heat the substrate 13 to a temperature sufficient for GaN crystal growth (1050 ± 50 ° C.). In addition, the first source gas generation unit 41 can be heated to a temperature (750 ° C.) or higher necessary for stable generation of GaCl by the lower heater 32.

<Vapor phase growth method>
An example of the gas layer growth conditions by the HVPE method will be listed. The supply amount of GaCl in the first source gas G1 and NH ₃ in the second source gas G2 was set to a molar ratio of 1:20. The pressure in the reaction vessel 10 was 1000 hPa.

  While the upper heater 31 and the lower heater 32 are turned on, the supply of the first source gas G1 and the second source gas G2 is started. Thereby, vapor phase growth of the GaN crystal layer on the substrate 13 can be performed. The growth rate of the GaN crystal layer is about 50 to 1000 μm / hour. When the GaN crystal layer 19 grows from the state of FIG. 2 to the state of FIG. 5, the actuator 15 starts control to move the substrate holder 11 upward (in the direction of arrow Y10) along the central axis A1. The rising speed of the substrate holder 11 is equivalent to the growth speed of the GaN crystal layer 19. The growth rate may be predicted by calculation or may be calculated by actual measurement. In the state of FIG. 5, the distance D3 from the substrate holding surface 11a to the lower surface 12a of the ring plate 12 is larger than the distance D4 from the substrate holding surface 11a to the surface 19a of the GaN crystal layer 19 by a predetermined distance PD. is there. In other words, the state of FIG. 5 is a state in which the lower surface 12a of the ring plate 12 protrudes toward the shower head 50 by a predetermined distance PD with respect to the surface 19a of the GaN crystal layer 19. The predetermined distance PD can be determined to an arbitrary value by experiments or the like.

  FIG. 6 shows a state in which the GaN crystal layer 19 is further grown from the state of FIG. 5 by the thickness T1. Since the rising speed of the substrate holder 11 is equivalent to the growth speed of the GaN crystal layer 19, the substrate holder 11 is also raised by a distance equivalent to the thickness T1. As a result, the state where the distance D3 is larger than the distance D4 by the predetermined distance PD is maintained. Further, the distance D5 between the surface 19a of the GaN crystal layer 19 and the surface of the shower head 50 (gas supply port) is maintained constant in FIGS.

<Effect>
First, a comparative example will be described with reference to FIGS. The comparative example is an example when the ring plate 12 according to the present embodiment is not provided. When the GaN crystal layer 19 grows from the state shown in FIG. 7 to the state shown in FIG. 8, the substrate holder 11 is moved upward along the central axis A1 (in the direction of arrow Y10) as the thickness increases. ) Will be described. In this case, the distance D5 between the surface 19a of the GaN crystal layer 19 and the surface of the shower head 50 (gas supply port) is maintained constant. However, the distance D6 between the lower surface 11cs of the support portion 11c disposed on the outer periphery of the GaN crystal layer 19 and the surface of the shower head 50 is not constant, and increases as the substrate holder 11 rises. As a result, the flow of the first and second source gases in the outer peripheral portion of the substrate cannot be maintained constant. That is, the gas flow Y20a shown in FIG. 7 is different from the gas flow Y20b shown in FIG. Then, the flow path of the gas flow becomes unstable, and the supply of the raw material to the surface 19a of the GaN crystal layer 19 and the temperature distribution change from the initial stage of growth, which may deteriorate the crystal quality and distribution. In addition, the end face 19b of the outer peripheral portion of the GaN crystal layer 19 which has been grown thickly with the crystal end face opened is not perpendicular to the surface (c-plane) of the substrate 13 but becomes a tapered face (see FIG. 8). This is because the tapered surface is more stable than the vertical surface. Such a tapered surface is a surface more stable than the m-plane ({10-11} plane) or a plane more stable than the a-plane ({11-21} plane, {11-22} plane). And when these taper surfaces take in oxygen, a lattice constant will become small and a stress will generate | occur | produce, and the grown GaN crystal layer 19 will crack.

  On the other hand, the vapor phase growth apparatus 1 of the present embodiment includes a ring plate 12 as shown in FIGS. The position of the ring plate 12 is fixed with respect to the shower head 50. Therefore, even when the substrate holder 11 is moved upward as the thickness of the GaN crystal layer 19 increases, the distance D7 between the lower surface 12a of the ring plate 12 and the surface of the shower head 50 can be made constant. As a result, as a first effect of the ring plate 12, the present inventors can obtain a uniform crystal in the thickness direction even when the GaN crystal layer 19 is grown for a long time (that is, thick film growth). I found it. This is presumably because the flow of the first and second source gases on the outer periphery of the substrate can be kept constant by the ring plate 12 even when the substrate holder 11 is raised. That is, it is considered that the gas flow Y20 shown in FIGS. 5 and 6 can be made the same during the growth of the GaN crystal layer 19.

  Further, the present inventors have found that, as a second effect of the ring plate 12, the end face 19 b of the outer peripheral portion of the GaN crystal layer 19 can be made perpendicular to the surface of the substrate 13. This is considered to be because the lower surface 12a of the ring plate 12 can be protruded toward the shower head 50 by a predetermined distance PD with respect to the surface 19a of the GaN crystal layer 19 (FIGS. 5 and 6). reference). This will be specifically described. By projecting the lower surface 12 a of the ring plate 12, gas flow can be retained in the region R <b> 1 near the boundary between the ring plate 12 and the GaN crystal layer 19. A part of the staying gas contributes to the formation of a vertical crystal plane (for example, m plane ({1-100} plane) or a plane ({11-20} plane)) along the wall surface. Conceivable. Thereby, it is possible to prevent a situation in which oxygen atoms are taken into the grown GaN crystal layer end face 19b and the GaN crystal layer 19 is cracked. In addition, when a plurality of wafers are cut out from the GaN crystal layer 19, it becomes possible to cut out a wafer having a certain area.

  FIG. 9 is a schematic cross-sectional view of the vapor phase growth apparatus 201 according to the second embodiment as viewed from the side. The vapor phase growth apparatus 201 according to the second embodiment changes the supply direction of the first raw material gas G1 and the second raw material gas G2 from the upward direction to the horizontal direction with respect to the vapor phase growth apparatus 1 according to the first embodiment, and the substrate. It has a configuration in which the orientation of the surface is changed from downward to upward. Since the basic configuration of the vapor phase growth apparatus 201 according to the second embodiment is the same as that of the vapor phase growth apparatus 1 according to the first embodiment, detailed description thereof is omitted.

  The vapor phase growth apparatus 201 includes a reaction vessel 210, a substrate holder 211, a ring plate 212, a first source gas supply pipe 221, a second source gas supply pipe 222, and a gas exhaust pipe 271. The substrate holder 211 includes a holder main body 211b and a support portion 211c. A substrate holding surface 211 a is provided on the upper surface of the substrate holder 211. The substrate 213 is held on the substrate holding surface 211a.

  A ring plate 212 is arranged on the upper side of the substrate holder 211. An upper surface 212a of the ring plate 212 is a surface corresponding to the substrate holding surface 211a. In the present embodiment, the upper surface 212a is a plane parallel to the substrate holding surface 211a. The ring plate 212 includes a hole 212 b corresponding to the substrate 213.

  An actuator 215 is connected to the lower part of the substrate holder 211 via a rotation shaft 214. The substrate holder 211 can be moved in the vertical direction (z direction in FIG. 9) along the central axis A2 perpendicular to the substrate holding surface 211a.

  The reaction vessel 210 is connected to a first source gas supply pipe 221 that supplies a first source gas G1 and a second source gas supply pipe 222 that supplies a second source gas G2. A first source gas supply pipe 221 is disposed inside the second source gas supply pipe 222. A first source gas generation unit 241 is disposed on the path of the first source gas supply pipe 221. Metal gallium 243 is stored inside the first source gas generation unit 241. HCl gas is supplied to the inlet of the first source gas supply pipe 221, and the first source gas G1 is discharged from the gas supply port. The second source gas G2 is supplied to the inlet of the second source gas supply pipe 222, and the second source gas G2 is discharged from the gas supply port. A gas exhaust pipe 271 is connected to the reaction vessel 210. The source gas used for the vapor phase growth of GaN is discharged to the vent line via the gas exhaust pipe 271.

  A heater 231 is disposed on the outer periphery of the reaction vessel 210 so as to surround the substrate holder 211. The heater 231 is a device that heats the substrate 213 by a hot wall method. Thereby, the substrate 213 can be maintained at a temperature sufficient for GaN crystal growth (1050 ± 50 ° C.). Further, precipitation of by-products on the inner wall of the reaction vessel 210 can be suppressed. A heater 233 is disposed outside the second source gas supply pipe 222 so as to surround the first source gas generator 241. Thereby, in order to generate GaCl, the 1st source gas generating part 241 can be maintained at 750 ° C or more.

<Effect>
The vapor phase growth apparatus 201 according to the second embodiment includes a ring plate 212. The ring plate 212 is fixed in the reaction vessel 210. Therefore, the distance between the upper surface 212a of the ring plate 212 and the surface of the GaN crystal layer is made constant by setting the descending speed of the substrate holder 211 and the growth speed of the GaN crystal layer grown on the substrate 213 to be equal. be able to. As a result, even when the substrate holder 211 is lowered, the flow of the first and second source gases on the outer periphery of the substrate can be kept constant. A homogeneous GaN crystal layer 19 can be grown in the thickness direction. In addition, the stagnation of the gas flow can be generated in the region of the outer peripheral portion of the surface of the GaN crystal layer. As a result, the end face of the outer peripheral portion of the grown GaN crystal layer can be made perpendicular to the surface of the substrate 213. Therefore, it is possible to prevent a situation in which the grown GaN crystal layer is cracked.

  FIG. 10 is a schematic cross-sectional view of the vapor phase growth apparatus 301 according to the third embodiment viewed from the side. The vapor phase growth apparatus 301 according to the third embodiment is different from the vapor phase growth apparatus 201 according to the second embodiment in that the positions of the first source gas supply pipe 221 and the second source gas supply pipe 222 are positioned from the right side of the substrate to above the substrate. The structure moved to the side is provided. Further, the gas exhaust pipe 271 is moved from the left side of the substrate to the lower side of the substrate. Since the same reference numerals are given to the same components as those of the vapor phase growth apparatus 201 of the second embodiment, detailed description thereof is omitted.

  Also in the vapor phase growth apparatus 301 of the third embodiment, the lowering speed of the substrate holder 211 and the growth speed of the GaN crystal layer grown on the substrate 213 are set to be equal, so that the upper surface 212a of the ring plate 212 and the GaN crystal The distance from the surface of the layer can be constant. Since the flow of the first and second source gases on the outer periphery of the substrate can be maintained constant, a homogeneous GaN crystal layer can be grown in the thickness direction. Further, since the gas flow can be retained in the region of the outer peripheral portion of the surface of the GaN crystal layer, the end surface of the outer peripheral portion of the grown GaN crystal layer can be made perpendicular to the surface of the substrate 213. Become.

<Modification>
As mentioned above, although the Example of this invention was described in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

  The lower surface 12a of the ring plate 12 described in FIG. 2 is not limited to a plane. A curved surface may be sufficient and a part may be a plane. When the lower surface 12a includes a flat portion, the flat portion may have an inclination with respect to the substrate holding surface 11a. The same applies to the upper surface 212a of the ring plate 212 of FIGS.

  The shape of the substrate 13 is not limited to a circle. A substrate having a shape such as a square or a hexagon can also be used.

  The ring plates 12 and 212 are not limited to a circle, but may be a polygon or a rectangle. Further, the ring plates 12 and 212 may be substantially ring-shaped, and need not be completely closed. For example, it may be C-shaped.

  Although the case where the distance D2 is equal to or greater than the distance D1 has been described with reference to FIG. For example, the distance D2 may be smaller than the distance D1. Thereby, even when the crystal diameter is reduced in the initial period until the surface of the GaN crystal layer 19 reaches the upper surface of the ring plate 12 (that is, the period until the ring plate 12 starts to function), the crystal diameter after the reduction is reduced. It is possible to correspond to the inner diameter of the hole 12b of the ring plate 12.

  Although the case where the surface of the seed substrate is the + c plane has been described, the present invention is not limited to this form. Various surfaces can be used as the surface of the seed substrate.

  As an example of forming the end face perpendicular to the crystal surface, the case of the m-plane ({1-100} plane) or the a-plane ({11-20} plane) has been described, but the present invention is not limited to this form. Various crystal planes and intermediate surface forms can be used.

Although tungsten has been described as an example of a metal capable of decomposing NH ₃ by a catalytic effect, the material is not limited to this material. Tungsten oxide (WOx), tungsten carbide (WCx), tungsten nitride (WNx), and the like can also be used. Metals containing tungsten (tungsten alloys) and oxides, carbides, and nitrides thereof can also be used. Other metals such as ruthenium, iridium, platinum, molybdenum, palladium, rhodium, iron, nickel, rhenium, etc. can also be used. In addition, oxides, carbides, nitrides of these metals, alloys containing these metals, and the like can also be used.

  The temperature sufficient for GaN crystal growth was described as 1050 ± 50 ° C. Further, it has been described that the temperature necessary for the generation of GaCl is 750 ° C. or higher. However, these temperatures are exemplary. For example, the temperature sufficient for GaN crystal growth may be in the range of 1050 ° C. ± 100 ° C.

  The number and arrangement of the first source gas supply pipes and the second source gas supply pipes described in this specification are merely examples, and are not limited to this form.

The technique described in this specification can be applied not only to the HVPE method but also to various growth methods. For example, it can be applied to a MOVPE (Metal Organic Vapor Phase Epitaxy) method. In this case, trimethylgallium (Ga (CH ₃ ) ₃ )) or the like may be used as the first source gas G1.

The technique described in this specification is applicable not only to GaN but also to crystal growth of various compound semiconductors. For example, it can be applied to the growth of GaAs crystals. In this case, arsine (AsH ₅ ) may be used as the second source gas G2.

The first raw material gas G1, the second source gas G2, may be flowed together with a carrier gas such as _{H 2} or _{N 2.}

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

  The ring plate 12 is an example of a ring portion. The lower surface is an example of a first surface. The upper surface is an example of a second surface.

  1: Vapor growth apparatus 10: Reaction vessel 11: Substrate holder 12, 212: Ring plate 15: Actuator 17, 18, 53: Predetermined metal 21, 221: First source gas supply pipe 22, 222: Second source gas supply Tubes 41, 241: first source gas generator 50: shower head

Claims (7)

A reaction vessel;
A substrate holder disposed in the reaction vessel and having a substrate holding surface for holding the substrate on the first surface;
A ring portion having a hole corresponding to the substrate held on the substrate holding surface;
A source gas supply pipe for supplying a first source gas and a second source gas that reacts with the first source gas into the reaction vessel, wherein the first source gas and the second source gas are on the surface of the substrate. The source gas supply pipe, which is a source gas for growing a compound semiconductor crystal;
An actuator for moving at least one of the substrate holder and the ring portion along an axis perpendicular to the substrate holding surface, the surface of the compound semiconductor crystal growing on the substrate and the ring portion The actuator for maintaining a constant distance from the surface;
An apparatus for vapor phase growth of compound semiconductors. The actuator moves the substrate holder to the second surface side opposite to the first surface,
2. The vapor phase growth apparatus according to claim 1, wherein a movement speed of the substrate holder is equal to a growth speed in a thickness direction of the crystal of the compound semiconductor.   The actuator maintains a state in which the distance from the substrate holding surface to the surface of the ring portion is larger by a predetermined distance than the distance from the substrate holding surface to the surface of the compound semiconductor crystal grown on the substrate. The vapor phase growth apparatus according to claim 1 or 2.   4. The vapor phase growth apparatus according to claim 1, wherein a surface of the ring portion is covered with a predetermined metal capable of decomposing the second source gas by a catalytic effect.   5. The gas according to claim 4, wherein the predetermined metal includes tungsten or a metal containing tungsten, an oxide of tungsten or a metal containing tungsten, a carbide of tungsten or a metal containing tungsten, or a nitride of tungsten or a metal containing tungsten. Phase growth equipment. A gas supply port of the source gas supply pipe is disposed at a position facing the substrate holding surface;
The actuator moves the substrate holder so as to maintain a constant distance between the surface of the compound semiconductor crystal growing on the substrate and the gas supply port;
The vapor phase growth apparatus according to any one of claims 1 to 5. The first source gas is a gas containing GaCl;
The vapor phase growth apparatus according to claim 1, wherein the second source gas is a gas containing NH ₃ .

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