JP7002731B2 - Vapor deposition equipment - Google Patents

Description

This specification discloses a technique relating to a vapor phase growth apparatus for a compound semiconductor.

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

JP-A-2002-316892

If GaN long crystals can be grown, a plurality of wafers can be produced from one long crystal, so that the substrate manufacturing cost can be reduced. However, it is difficult to grow a long crystal of GaN. One of the factors is that the precipitation of GaN polycrystals at the supply port of the raw material gas causes clogging of the gas pipe and change of the gas flow, resulting in abnormal growth.

This specification discloses a vapor deposition apparatus. This vapor deposition apparatus comprises a reaction vessel. The vapor deposition apparatus comprises a wafer holder located within the reaction vessel. The vapor phase growth apparatus includes a first raw material gas supply pipe that supplies the first raw material gas into the reaction vessel. The vapor phase growth apparatus includes a second raw material gas supply pipe that supplies a second raw material gas that reacts with the first raw material gas into the reaction vessel. The vapor phase growth apparatus includes a first heating unit. The surface of the region near at least one gas supply port of the first raw material gas supply pipe and the second raw material gas supply pipe is covered with a predetermined metal. The predetermined metal is a metal capable of decomposing the second raw material gas by a catalytic effect. The first heating unit heats the surface of the predetermined metal to 800 ° C. or higher.

In the vapor phase growth apparatus of the present specification, the catalytic effect of the predetermined metal can be enhanced by heating the surface of the predetermined metal to 800 ° C. or higher. Therefore, the second raw material gas can be decomposed on the surface of the region near the gas supply port. This makes it possible to suppress the precipitation of GaN polycrystals in the region near the gas supply port.

A shower head in which a plurality of gas supply ports of the first raw material gas supply pipe and a plurality of gas supply ports of the second raw material gas supply pipe are arranged may be further provided. At least the surface of the shower head on the gas supply port side may be covered with a predetermined metal.

Gas supply ports may be arranged at the ends of the first raw material gas supply pipe and the second raw material gas supply pipe. The inner wall and the outer wall of the first raw material gas supply pipe may be covered with a predetermined metal in the region near the end of the first raw material gas supply pipe on the gas supply port side. The inner wall and the outer wall of the second raw material gas supply pipe may be covered with a predetermined metal in the region near the end of the second raw material gas supply pipe on the gas supply port side.

The inner diameter of the second raw material gas supply pipe may be larger than the outer diameter of the first raw material gas supply pipe. The first raw material gas supply pipe may be arranged inside the second raw material gas supply pipe.

The first raw material gas supply pipe and the second raw material gas supply pipe may form an integral common pipe. The first raw material gas and the second raw material gas may be supplied to the inlet located on the opposite side of the gas supply port of the common pipe. The inner wall of the common pipe may be covered with a predetermined metal over the entire length from the inlet to the gas supply port. A second heating unit that heats the common pipe to 800 ° C. or higher over the entire length from the inlet to the gas supply port may be further provided.

A third heating unit that heats the temperature of the region between the gas supply port of the first raw material gas supply pipe and the second raw material gas supply pipe and the wafer holder to 500 ° C. or higher may be provided.

A first supply unit for supplying the first raw material gas may be provided at an inlet located on the opposite side of the gas supply port of the first raw material gas supply pipe. A second supply unit for supplying the second raw material gas may be provided at an inlet located on the opposite side of the gas supply port of the second raw material gas supply pipe. The first supply unit and the second supply unit may supply the first raw material gas and the second raw material gas while the surface of the predetermined metal is 800 ° C. or higher.

The first supply unit and the second supply unit may start supplying the first raw material gas and the second raw material gas after the surface of the predetermined metal is heated to 800 ° C. or higher by the first heating unit. The first heating unit may end the heating of the surface of the predetermined metal after the supply of the first raw material gas and the second raw material gas is stopped by the first supply unit and the second supply unit.

The predetermined metal may include tungsten or a metal containing tungsten, an oxide of tungsten or a metal containing tungsten, a carbide of a metal containing tungsten or tungsten, or a nitride of a metal containing tungsten or tungsten.

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

It is schematic cross-sectional view of the vapor phase growth apparatus which concerns on Example 1 as seen from the side. It is the figure which looked at the sectional view in line II-II from the vertical upper side. It is schematic cross-sectional view of the vapor phase growth apparatus which concerns on Example 2 as seen from the side. It is the schematic sectional drawing which looked at the side view of the vapor phase growth apparatus which concerns on Example 3. FIG. It is the schematic sectional drawing which looked at the side view of the vapor phase growth apparatus which concerns on Example 4. FIG. It is a schematic sectional view of the shower head provided with a mixing chamber as seen from the side.

<Structure of vapor phase growth device>
FIG. 1 shows a schematic cross-sectional view of the vapor phase growth apparatus 1 according to the technique of the present specification as viewed from the side surface. The vapor phase growth apparatus 1 is an example of an apparatus configuration for carrying out the 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 raw material gas supply unit 20 and a wafer holder 11 are arranged inside the reaction vessel 10.

The structure of the raw material gas supply unit 20 will be described. The raw material gas supply unit 20 is a cylindrical member. The raw material gas supply unit 20 includes a cylindrical cover 24. A disk-shaped shower head 50 is arranged at the upper end of the cover 24. An inlet of the HCl gas supply pipe 25 and an inlet of the second raw material gas supply pipe 22 are arranged in the lower part of the raw material gas supply unit 20. A first valve 61 is arranged 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 raw material gas generation unit 41. The first raw material gas generation unit 41 stores metallic gallium inside. The first raw material gas generation unit 41 is a portion that generates the first raw material gas G1 containing GaCl. The first raw material gas supply pipe 21 is a pipe for supplying the first raw material gas G1. The inlet of the first raw material gas supply pipe 21 is connected to the first raw material gas generation unit 41. The outlet of the first raw material gas supply pipe 21 is connected to the shower head 50. A second valve 62 is arranged at the inlet of the second raw material gas supply pipe 22. The second valve 62 controls the supply of the gas including the second raw material gas G2. The second raw material gas G2 is a gas containing NH ₃ . The outlet of the second raw material gas supply pipe 22 is connected to the shower head 50.

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

The shower head 50 is a portion for discharging the first raw material gas G1 and the second raw material gas G2 to the vicinity of the surface of the wafer 13. The first raw material gas G1 and the second raw material gas G2 discharged from the shower head 50 flow vertically upward in the reaction vessel 10 in the direction of arrow Y1. The structure of the shower head 50 will be described with reference to FIG. FIG. 2 is a view of the cross-sectional view taken along the line II-II of FIG. 1 as viewed from above vertically. On the surface of the shower head 50, a plurality of first gas supply ports 51 for discharging the first raw material gas G1 and a plurality of second gas supply ports 52 for discharging the second raw material gas G2 are arranged. By discharging the first raw material gas G1 and the second raw material gas G2 from a large number of gas supply ports, the amount of gas supplied to the surface of the wafer 13 can be made uniform in the wafer surface. Therefore, it is possible to suppress in-plane variation of the grown GaN crystal thickness.

On the surface of the shower head 50, a region where the first gas supply port 51 and the second gas supply port 52 are not formed is covered with a predetermined metal 53. In other words, the surface of the region near the first gas supply port 51 and the second gas supply port 52 is covered with the predetermined metal 53. The predetermined metal 53 is a metal capable of decomposing NH ₃ contained in the second raw material gas by a catalytic effect. The predetermined metal 53 may be made of a metal plate having a thickness of several millimeters. The metal plate may be formed with a plurality of holes corresponding to the positions and hole diameters of the first gas supply port 51 and the second gas supply port 52. In this embodiment, tungsten is used as the predetermined metal.

A gas exhaust pipe 23 for exhausting the gas in the reaction vessel 10 is configured around the raw material gas supply unit 20. This will be described with reference to FIG. A cylindrical raw material 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 raw material gas supply unit 20. This annular gap functions as a gas exhaust pipe 23. That is, the gas exhaust pipe 23 is arranged so as to extend vertically downward (that is, in the −z axis direction in FIG. 1) along the outer wall of the raw material gas supply unit 20 and the inner wall of the reaction vessel 10. As a result, the gas exhaust pipe 23 can be arranged so as to surround the outer periphery of the shower head 50, the first raw material gas supply pipe 21, and the second raw material gas supply pipe 22.

Further, the inlet 23a (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 the arrow Y2 in FIG. 1, the first raw material gas G1 and the second raw material gas G2 used for GaN crystal growth on the surface of the wafer 13 are exhausted in the side surface direction of the shower head 50 and downward in the wafer 13. Can be made to. An outlet 23b of the gas exhaust pipe 23 is arranged at the lower end of the reaction vessel 10. The gas sucked from the inlet 23a of the gas exhaust pipe 23 is discharged to the vent line from the outlet 23b.

The wafer holder 11 is arranged in the reaction vessel 10. The wafer holder 11 is provided with a wafer holding portion 12 on the lower surface thereof. The wafer holding unit 12 holds the wafer 13 so that the surface of the wafer 13 faces substantially vertically downward. Note that "substantially vertically downward" is not limited to the mode in which the normal of the wafer coincides with the vertically downward direction. The concept is that the normal of the wafer includes an inclination of up to 45 degrees with respect to the vertical downward direction. In this embodiment, tungsten is arranged on the surface of the wafer holder 11. This has the effect of suppressing the precipitation of GaN polycrystals on the surface of the wafer holder 11.

The lower end of the rotating shaft 14 is connected to the upper part of the wafer holder 11. The upper end of the rotating shaft 14 projects to the outside of the reaction vessel 10. The upper end of the rotating shaft 14 is connected to the drive mechanism 15. As a result, the wafer holder 11 can be rotated and moved up and down in the reaction vessel 10.

A specific gas supply pipe 16 is provided in the upper part of the reaction vessel 10. The specific gas G3 is supplied to the inlet of the specific gas supply pipe 16. As shown by the arrow Y3 in FIG. 1, the specific gas G3 flows vertically downward from above the wafer holder 11 and is sucked into the inlet 23a of the gas exhaust pipe 23. Thereby, the 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 raw material gas G1 and the second raw material 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 arranged on the outside of the reaction vessel 10. A partition wall 42 is arranged near the boundary between the region H1 in which the upper heater 31 is arranged and the region H2 in which the lower heater 32 is arranged. The upper heater 31 is arranged so as to surround the periphery of the regions R1 to R3 shown in FIG. The region R1 is a region including the wafer 13. The region R1 is a region that needs to maintain a temperature (1050 ± 50 ° C.) sufficient for GaN crystal growth. The region R2 is a region between the gas supply port of the shower head 50 and the wafer holder 11. The region R2 is a region that needs to be maintained at 500 ° C. or higher so that GaCl in the raw material gas does not decompose. The region R3 is a region including a predetermined metal 53 that covers the surface of the shower head 50. The region R3 is a region that needs to be maintained at 800 ° C. or higher in order to suppress the precipitation of GaN polycrystals.

The lower heater 32 is arranged so as to surround the region R4. The region R4 is a region including the first raw material gas generation unit 41. The region R4 is a region that needs to be maintained at a temperature (750 ° C.) or higher required for stable generation of GaCl.

<Chemical vapor deposition method>
A method of performing vapor deposition of a GaN layer on a wafer 13 by the HVPE method will be described. An example of air layer growth conditions is listed. The molar ratio of GaCl in the first raw material gas G1 and _NH3 in the second raw material gas G2 was 1:20. The pressure in the reaction vessel 10 was 1000 hPa.

In the first step, the upper heater 31 is turned on. Region R1 (wafer 13), region R2 (region between the gas supply port and the wafer holder 11), and region R3 (predetermined metal 53) are heated to 1050 ± 50 ° C. As a result, the upper heater 31 can maintain all of the regions R1 to R3 above the required temperature. Further, by turning on the lower heater 32, the region R4 (first raw material gas generating unit 41) is heated to 750 ° C.

When the surface of the predetermined metal 53 reaches 800 ° C. or higher, the process proceeds to the second step. The transition timing to the second step may be determined by measuring the surface temperature of the predetermined metal 53 with various sensors. In the second step, the supply of the first raw material gas G1 and the second raw material gas G2 is started by opening the first valve 61 and the second valve 62. As a result, vapor phase growth of the GaN layer can be performed on the wafer 13. When the vapor phase growth is completed, the process proceeds to the third step, and the first valve 61 and the second valve 62 are closed. The supply of the first raw material gas G1 and the second raw material gas G2 is terminated. After that, the process proceeds to the fourth step, and the upper heater 31 and the lower heater 32 are turned off. As a result, the heating of the surface of the predetermined metal 53 is completed.

<Effect>
In the HVPE method, it is difficult to grow a long crystal (also referred to as a thick film crystal) on the c-plane of GaN. This is because it is difficult to suppress the occurrence of abnormal growth. As an example of the cause of the occurrence of abnormal growth, GaN polycrystals are deposited on the first gas supply port 51 and the second gas supply port 52 arranged on the surface of the shower head 50, resulting in gas pipe clogging or gas flow change. Can be mentioned. As a countermeasure, it is conceivable to cover the surface of the shower head 50 with a predetermined metal (eg, tungsten) capable of decomposing NH ₃ by a catalytic effect. However, the present inventors have stated that in order to prevent the precipitation of GaN polycrystals, it is not enough to cover the surface of the shower head 50 with a predetermined metal, and the surface temperature of the predetermined metal needs to be 800 ° C. or higher. I found it. This is because it is considered that the active hydrogen generated by decomposing NH ₃ by the catalytic effect suppresses the precipitation of GaN polycrystals. Further, it is considered that 800 ° C. or higher is required for the active hydrogen to react with the GaN polycrystal. Therefore, the vapor phase growth apparatus 1 of the first embodiment includes an upper heater 31 that surrounds the region R3 containing the predetermined metal 53. As a result, the surface of the predetermined metal can be heated to 800 ° C. or higher, so that precipitation of GaN polycrystals on the surface of the shower head 50 can be suppressed.

In the vapor phase growth method of Example 1, the supply of the first raw material gas G1 and the second raw material gas G2 is started when the surface of the predetermined metal 53 reaches 800 ° C. or higher (second step). Further, after closing the first valve 61 and the second valve 62 in the third step, the upper heater 31 is turned off in the fourth step. By the above flow, the first valve 61 and the second valve 62 are controlled so that "the surface of the predetermined metal 53 supplies the first raw material gas G1 and the second raw material gas G2 during the period of 800 ° C. or higher". Can be done. Therefore, it is possible to suppress the precipitation of GaN polycrystals on the surface of the shower head 50.

FIG. 3 shows a schematic cross-sectional view of the vapor phase growth apparatus 201 according to the second embodiment as viewed from the side surface. The vapor phase growth apparatus 201 is an example of an apparatus configuration for carrying out the HVPE method. The vapor phase growth apparatus 201 includes a reaction vessel 210, a susceptor 211, a first raw material gas supply pipe 221 and a second raw material gas supply pipe 222, and a gas exhaust pipe 271. The susceptor 211 is housed in the reaction vessel 210. The wafer 213 is held on the wafer holding surface of the susceptor 211.

A first raw material gas supply pipe 221 for supplying the first raw material gas G1 and a second raw material gas supply pipe 222 for supplying the second raw material gas G2 are connected to the reaction vessel 210. The inner diameter D1 of the second raw material gas supply pipe 222 is larger than the outer diameter D2 of the first raw material gas supply pipe 221. A first raw material gas supply pipe 221 is arranged inside the second raw material gas supply pipe 222. A gap is formed between the outer wall of the first raw material gas supply pipe 221 and the inner wall of the second raw material gas supply pipe 222, and the second raw material gas G2 flows through the gap. The end region E1 of the first raw material gas supply pipe 221 and the second raw material gas supply pipe 222 functions as a gas supply port. In the vicinity of the end region E1, the inner and outer walls of the first raw material gas supply pipe 221 and the second raw material gas supply pipe 222 are covered with a predetermined metal 253.

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

A heater 231 is arranged on the outer periphery of the reaction vessel 210 so as to surround the susceptor 211. The heater 231 is a device that heats the wafer 213 by a hot wall method. As a result, the wafer 213 can be maintained at a temperature sufficient for GaN crystal growth (1050 ± 50 ° C.). Further, it is possible to suppress the precipitation of by-products on the inner wall of the reaction vessel 210. A heater 232 is arranged on the outside of the reaction vessel 210 so as to surround the end region E1. Thereby, the predetermined metal 253 arranged in the end region E1 can be maintained at 800 ° C. or higher. A heater 233 is arranged on the outside of the second raw material gas supply pipe 222 so as to surround the first raw material gas generation unit 241. As a result, the first raw material gas generation unit 241 can be maintained at 750 ° C. or higher in order to generate GaCl.

<Effect>
The vapor phase growth apparatus 201 of the second embodiment includes a heater 232 that surrounds a predetermined metal 253 arranged in the vicinity of the gas supply port (end region E1). As a result, the surface of the predetermined metal 253 can be heated to 800 ° C. or higher, so that precipitation of GaN polycrystals at the gas supply port can be suppressed.

FIG. 4 shows a schematic cross-sectional view of the vapor phase growth apparatus 301 according to the third embodiment as viewed from the side surface. The vapor phase growth apparatus 301 according to the third embodiment positions the first raw material gas supply pipe 221 and the second raw material gas supply pipe 222 with respect to the vapor phase growth apparatus 201 according to the second embodiment from the right side of the wafer. It has a configuration that has been moved upward. Further, the gas exhaust pipe 271 is provided with a configuration in which the position of the gas exhaust pipe 271 is moved from the left side surface side of the wafer to the lower side side. Since the same components as those of the vapor phase growth apparatus 201 of the second embodiment are designated by the same reference numerals, detailed description thereof will be omitted.

Also in the vapor phase growth apparatus 301 of Example 3, the surface of the predetermined metal 253 can be heated to 800 ° C. or higher by the heater 232. Therefore, it is possible to suppress the precipitation of GaN polycrystals at the gas supply port.

FIG. 5 shows a schematic cross-sectional view of the vapor phase growth apparatus 401 according to the fourth embodiment as viewed from the side surface. The vapor phase growth apparatus 401 according to the fourth embodiment has a configuration provided with a common pipe 423 with respect to the vapor phase growth apparatus 201 according to the second embodiment. Since the same components as those of the vapor phase growth apparatus 201 of the second embodiment are designated by the same reference numerals, detailed description thereof will be omitted.

The first raw material gas supply pipe 421 and the second raw material gas supply pipe 422 are connected to the common pipe 423 at the connection portion J1. In other words, the first raw material gas supply pipe 421 and the second raw material gas supply pipe 422 form an integral common pipe 423. The end region E2 of the common pipe 423 functions as a gas supply port.

In the common pipe 423, the position of the inlet of the first raw material gas G1 and the second raw material gas G2 is defined as the position P1. Further, the position of the gas supply port is set to the position P2. The region extending over the entire length from the position P1 to the position P2 is referred to as a region R11. The inner wall of the common pipe 423 is covered with a predetermined metal 453 over the entire region including the region R11. Further, in the vicinity of the end region E2, the inner wall and the outer wall of the common pipe 423 are covered with the predetermined metal 453.

The first raw material gas G1 is supplied to the inlet of the first raw material gas supply pipe 421, and the second raw material gas G2 is supplied to the inlet of the second raw material gas supply pipe 422. The first raw material gas G1 and the second raw material gas G2 are mixed inside the common pipe 423, and the mixed gas is discharged from the gas supply port of the common pipe 423.

Heaters 432 and 433 are arranged so as to surround the common pipe 423 over the entire length of the region R11. Thereby, the predetermined metal 453 can be maintained at 800 ° C. or higher over the entire region including the region R11.

<Effect>
In the vapor phase growth apparatus 401 of the fourth embodiment, the first raw material gas G1 and the second raw material gas G2 can be mixed by using the region R11 from the position P1 to the position P2 of the common tube 423. Since sufficient distance and time can be taken to mix both gases, the two gases can be discharged in a sufficiently mixed state from the gas supply port of the common pipe 423. It is possible to grow a good GaN crystal at high speed, which is advantageous for cost reduction. Further, if a sufficient distance and time are taken to mix both gases, GaN polycrystals may precipitate on the inner wall of the common tube 423. Therefore, in the vapor phase growth apparatus 401 of the fourth embodiment, the surface of the predetermined metal 453 on the inner wall of the common tube 423 can be heated to 800 ° C. or higher by the heaters 432 and 433 over the entire length of the common tube 423. It is possible to suppress the precipitation of GaN polycrystals on the inner wall of the common tube 423.

<Modification example>
Although the examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples exemplified above.

Tungsten has been described as an example of a metal in which NH ₃ can be decomposed by a catalytic effect, but the material is not limited to this material. Tungsten oxide (WOx), tungsten carbide (WCx), tungsten nitride (WNx), and the like can also be used. Further, metals containing tungsten (tungsten alloy) and their oxides, carbides and nitrides can also be used. Other metals such as ruthenium, iridium, platinum, molybdenum, palladium, rhodium, iron, nickel and rhenium can also be used. Further, oxides, carbides and nitrides of these metals, alloys containing these metals and the like can also be used.

The structure of the shower head is not limited to the structure shown in the first embodiment. For example, the mixed gas in which the first raw material gas G1 and the second raw material gas G2 are mixed may be discharged from the shower head. FIG. 6 shows a schematic cross-sectional view of a shower head 50 provided with a mixing chamber 54 for generating a mixed gas, as viewed from the side surface. A first gas supply port 51 and a second gas supply port 52 of the shower head 50 are connected to the lower part of the mixing chamber 54. A plurality of gas supply ports 55 are arranged in the upper part of the mixing chamber 54. The inner wall and the outer wall of the mixing chamber 54 are covered with a predetermined metal 56. The first raw material gas G1 and the second raw material gas G2 are mixed inside the mixing chamber 54, and the mixed gas Gm is discharged from the gas supply port 55. Explain the effect. Since the mixed gas Gm can be discharged from the gas supply port 55 of the mixing chamber 54, the V / III ratio in the raw material gas supplied to the wafer can be made uniform. It is possible to grow a uniform GaN crystal. Moreover, since the V / III ratio can be increased, the growth rate of the GaN crystal can be increased. Further, when the mixing chamber 54 is not provided, it is necessary to secure a certain distance between the gas supply port and the wafer surface in order to sufficiently mix the first raw material gas G1 and the second raw material gas G2. However, in the structure of FIG. 6 including the mixing chamber 54, the gas supply port and the wafer surface can be brought closer to each other, so that the growth rate of the GaN crystal can be increased and the raw material efficiency can be increased to suppress the gas consumption. It becomes possible to do. Further, a heater 31 (see FIG. 1) is arranged so as to surround the mixing chamber 54. Thereby, the predetermined metal 56 can be maintained at 800 ° C. or higher over the entire mixing chamber 54. It is possible to suppress the precipitation of GaN polycrystals on the inner and outer walls of the mixing chamber 54.

In the first embodiment, it is assumed that the surface of the shower head 50 is covered with the predetermined metal 53, but the present invention is not limited to this form, and the side surface of the shower head 50 or the like may be covered with the predetermined metal 53. In Example 2-4, an embodiment in which the inner wall and the outer wall near the end of the gas supply pipe are covered with a predetermined metal has been described, but the present invention is not limited to this embodiment. The gas supply pipe itself may be formed of a material containing a predetermined metal.

In this embodiment, a mode in which the gas supply ports of both the first raw material gas supply pipe and the second raw material gas supply pipe are covered with a predetermined metal has been described, but the present invention is not limited to this mode. The surface of the region near the gas supply port of at least one gas supply pipe may be covered with a predetermined metal. For example, in the structure in which the first raw material gas supply pipe 221 is arranged inside the second raw material gas supply pipe 222 as in Example 2 (FIG. 3) and Example 3 (FIG. 4), the first raw material is used. GaN polycrystals are likely to precipitate in the region near the supply port of the gas supply pipe 221. Therefore, only the inner wall and the outer wall of the supply port of the first raw material gas supply pipe 221 may be covered with the predetermined metal 253. On the contrary, only the inner wall and the outer wall of the supply port of the second raw material gas supply pipe 222 may be covered with the predetermined metal 253.

In the first embodiment, the embodiment in which the regions R1 to R3 are surrounded by the upper heater 31 has been described, but the upper heater 31 may be divided into two or more. Thereby, the temperature of the regions R1 to R3 can be controlled individually.

The temperature sufficient for GaN crystal growth was described as 1050 ± 50 ° C. Further, it was explained that the temperature required for the generation of GaCl was 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.

Although the case where the first raw material gas G1 is a gas containing GaCl has been described, the present invention is not limited to this form. The first raw material gas G1 may be a gas having any chemical composition as long as it is a gas containing Ga. For example, the first raw material gas G1 may be a gas containing Ga trichloride (GaCl ₃ ). In this case, a growth temperature of about 1300 ° C. may be used. A GaN crystal may be grown on the N-plane (−c-plane). This makes it possible to expand the surface of the GaN crystal as it grows.

The number and arrangement of the first raw material gas supply pipe and the second raw material gas supply pipe described in the present specification are examples, and are not limited to this form.

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

The technique described in the present specification can be applied 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 raw material gas G2.

The first raw material gas G1 and the _second raw material gas G2 may be flown together with a carrier gas such as H2 or _N2 .

The technical elements described herein or in the drawings exhibit their 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 techniques exemplified in the present specification or the drawings can achieve a plurality of purposes at the same time, and achieving one of the purposes itself has technical usefulness.

The upper heater 31, the heater 232, and the heater 432 are examples of the first heating unit. The upper heater 31 is an example of the third heating unit. The first valve 61 is an example of the first supply unit. The second valve 62 is an example of the second supply unit.

1: Gas phase growth device 10: Reaction vessel 11: Wafer holder 21, 221 and 421: First raw material gas supply pipe 22, 222, 422: Second raw material gas supply pipe 23: Gas exhaust pipe 31: Upper heater 32: Lower heater 41: First raw material gas generator 50: Shower head 53, 253, 453: Predetermined metal 231, 232, 233, 432, 433: Heater

Claims (13)

With the reaction vessel,
The wafer holder arranged in the reaction vessel and
The first raw material gas supply pipe that supplies the first raw material gas into the reaction vessel,
A second raw material gas supply pipe that supplies the second raw material gas that reacts with the first raw material gas into the reaction vessel,
The first heating part and
Equipped with
The surface of the region near at least one gas supply port of the first raw material gas supply pipe and the second raw material gas supply pipe is covered with a predetermined metal.
The predetermined metal is a metal capable of decomposing the second raw material gas by a catalytic effect.
The second raw material gas is a gas that generates active hydrogen by being decomposed by the catalytic effect.
The first heating unit is a vapor phase growth apparatus for a compound semiconductor that heats the surface of the predetermined metal to 800 ° C. or higher. The second raw material gas is NH ₃ The vapor phase growth apparatus according to claim 1, wherein the gas comprises. Further, a shower head in which a plurality of gas supply ports of the first raw material gas supply pipe and a plurality of gas supply ports of the second raw material gas supply pipe are arranged is further provided.
The vapor phase growth apparatus according to claim 1 or 2 , wherein at least the surface of the shower head on the gas supply port side is covered with the predetermined metal. The gas supply port is arranged at the end of the first raw material gas supply pipe and the second raw material gas supply pipe.
In the region near the end of the first raw material gas supply pipe on the gas supply port side, the inner wall and the outer wall of the first raw material gas supply pipe are covered with the predetermined metal.
The gas according to claim 1 or 2 , wherein the inner wall and the outer wall of the second raw material gas supply pipe are covered with the predetermined metal in the region near the end of the second raw material gas supply pipe on the gas supply port side. Phase growth device. The inner diameter of the second raw material gas supply pipe is larger than the outer diameter of the first raw material gas supply pipe.
The vapor phase growth apparatus according to claim 4 , wherein the first raw material gas supply pipe is arranged inside the second raw material gas supply pipe. The first raw material gas supply pipe and the second raw material gas supply pipe form an integral common pipe.
The first raw material gas and the second raw material gas are supplied to the inlet located on the opposite side of the gas supply port of the common pipe.
The inner wall of the common pipe is covered with the predetermined metal over the entire length from the inlet to the gas supply port.
The vapor phase growth apparatus according to claim 1 or 2 , further comprising a second heating unit that heats the common pipe to 800 ° C. or higher over the entire length from the inlet to the gas supply port. Claims 1 to 6 include a third heating unit that heats the temperature of the region between the gas supply port of the first raw material gas supply pipe and the second raw material gas supply pipe and the wafer holder to 500 ° C. or higher. The gas phase growth apparatus according to any one item. A first supply unit that supplies the first raw material gas to an inlet located on the opposite side of the gas supply port of the first raw material gas supply pipe.
A second supply unit that supplies the second raw material gas to an inlet located on the opposite side of the gas supply port of the second raw material gas supply pipe.
Equipped with
The first supply unit and the second supply unit supply the first raw material gas and the second raw material gas while the surface of the predetermined metal is 800 ° C. or higher, any one of claims 1 to 6 . The gas phase growth apparatus described in the section. The first supply unit and the second supply unit start supplying the first raw material gas and the second raw material gas after the surface of the predetermined metal is heated to 800 ° C. or higher by the first heating unit.
The first heating unit is claimed to end heating the surface of the predetermined metal after the supply of the first raw material gas and the second raw material gas is stopped by the first supply unit and the second supply unit. Item 8. The gas phase growth apparatus according to Item 8. 10 . The gas phase growth apparatus according to item 1. The first raw material gas is a gas containing GaCl, and is a gas containing GaCl.
The vapor phase growth apparatus according to any one of claims 1 to 10 , wherein the second raw material gas is a gas containing NH ₃ . The process of arranging the wafer in the reaction vessel and
The first supply step of supplying the first raw material gas into the reaction vessel using the first raw material gas supply pipe, and
A second supply step of supplying the second raw material gas that reacts with the first raw material gas into the reaction vessel by using the second raw material gas supply pipe.
It is a vapor phase growth method of a compound semiconductor comprising.
The surface of the region near at least one gas supply port of the first raw material gas supply pipe and the second raw material gas supply pipe is covered with a predetermined metal capable of decomposing the second raw material gas by a catalytic effect.
The second raw material gas is a gas that generates active hydrogen by being decomposed by the catalytic effect.
A method for vapor phase growth of a compound semiconductor, further comprising a step of heating the surface of the predetermined metal to 800 ° C. or higher. The second raw material gas is NH ₃ The gas phase growth method according to claim 12, wherein the gas comprises.

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