JP7728541B2 - Gallium nitride layer manufacturing apparatus and method for manufacturing a gallium nitride layer - Google Patents

Description

The present invention relates to a GaN layer manufacturing apparatus and a GaN layer manufacturing method for growing a GaN layer on a seed substrate made of gallium nitride (hereinafter simply referred to as GaN).

A manufacturing method has been proposed for constructing a wafer by sequentially growing a doped GaN layer, which is doped with impurities, and an undoped GaN layer, which is not doped with impurities, on a seed substrate made of GaN. Specifically, in this manufacturing method, when growing the doped GaN layer, a gallium-based gas and an ammonia-based gas are supplied into the growth chamber, along with a dopant gas containing impurities, to grow the doped GaN layer. When growing the undoped GaN layer, a gallium-based gas and an ammonia-based gas are supplied into the growth chamber, without supplying a dopant gas containing impurities, to grow the undoped GaN layer.

In this case, when growing a doped GaN layer, there is a possibility that foreign matter due to impurities may adhere to the growth vessel. Therefore, if an attempt is made to grow an undoped GaN layer immediately after growing a doped GaN layer, there is a possibility that foreign matter (i.e., impurities) adhering to the growth vessel may be mixed into the undoped GaN layer.

For example, Patent Document 1 proposes placing an adsorption layer containing indium (In) between a doped GaN layer and an undoped GaN layer. This allows foreign matter adhering to the growth vessel to be adsorbed onto the adsorption layer when the adsorption layer is formed. This prevents unwanted foreign matter from being mixed into the undoped GaN layer when the undoped GaN layer is grown. In other words, it prevents changes to the properties of the GaN layer.

JP 2014-96567 A

However, placing an indium-containing adsorption layer between the doped GaN layer and the undoped GaN layer makes it easier for lattice mismatch to occur between the adsorption layer and the doped and undoped GaN layers. Therefore, the above method may result in distortion of the GaN layer.

In view of the above, the present invention aims to provide a GaN layer manufacturing apparatus and a GaN layer manufacturing method that can suppress distortion of the GaN layer while suppressing changes in the properties of the GaN layer.

In order to achieve the above object, claim 1 provides a GaN layer manufacturing apparatus for growing a GaN layer (122) by supplying a gallium-based gas and an ammonia-based gas onto a seed substrate (121) made of GaN, the apparatus comprising: a growth apparatus (10) having a cylindrical growth vessel (100) in which a GaN layer is grown in a hollow portion (101a) constituting a reaction chamber; a pedestal (120) disposed within the hollow portion of the growth vessel and on which a seed substrate on which a GaN layer is grown is placed; a first supply pipe (310) provided in the growth apparatus for supplying a gallium-based gas for growing the GaN layer to the growth apparatus; and a second supply pipe (310) provided in the growth apparatus for supplying an ammonia-based gas for growing the GaN layer. The growth apparatus is provided with a piping (320), a third supply piping (330) that is provided in the growth apparatus and that supplies a dopant gas to the growth apparatus, and an etching gas supply piping (310, 350) that is provided in the growth apparatus and that supplies an etching gas to the growth apparatus, and after a doped GaN layer (122a) doped with impurities is grown on a seed substrate by supplying a gallium-based gas, an ammonia-based gas, and a dopant gas, and before growing a GaN layer (122b) different from the doped GaN layer, the seed substrate on which the doped gallium nitride layer has been grown is placed on a pedestal, and an etching gas is supplied from the etching gas supply piping to the growth apparatus to remove foreign matter adhering to the growth apparatus.

By removing foreign matter, when a doped GaN layer is grown and then a GaN layer different from the doped GaN layer is grown, it is possible to prevent foreign matter from being mixed into the different GaN layer, thereby preventing changes in the properties of the GaN layer. Furthermore, since this eliminates the need to place an adsorption layer, etc., lattice mismatch, etc., that would otherwise occur is less likely to occur, and distortion of the grown GaN layer can be prevented.

Claim 8 provides a method for manufacturing a GaN layer using the GaN layer manufacturing apparatus according to claim 1, comprising the steps of: preparing the GaN layer manufacturing apparatus according to claim 1; growing a doped GaN layer (122a) doped with impurities on a seed substrate by supplying a gallium-based gas, an ammonia-based gas, and a dopant gas; after growing the doped GaN layer, placing the seed substrate on which the doped gallium nitride layer has been grown on a pedestal and supplying an etching gas to the growth apparatus to remove foreign matter adhering to the growth apparatus; and, after removing the foreign matter, growing a GaN layer (122b) different from the doped GaN layer.

By removing foreign matter, when a doped GaN layer is grown and then a GaN layer different from the doped GaN layer is grown, it is possible to prevent foreign matter from being mixed into the different GaN layer, thereby preventing changes in the properties of the GaN layer. Furthermore, since this eliminates the need to place an adsorption layer, etc., lattice mismatch, etc., that would otherwise occur is less likely to occur, and distortion of the grown GaN layer can be prevented.

Note that the reference symbols in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described below.

1 is a cross-sectional schematic view of a GaN layer manufacturing apparatus according to a first embodiment. FIG. 2 is a schematic diagram showing a GaN layer grown on a seed substrate in the first embodiment. FIG. 10 is a cross-sectional view schematically illustrating a GaN layer manufacturing apparatus according to a second embodiment. FIG. 10 is a cross-sectional view schematically illustrating a GaN layer manufacturing apparatus according to a third embodiment. FIG. 10 is a cross-sectional view schematically illustrating a GaN layer manufacturing apparatus according to a fourth embodiment. FIG. 10 is a cross-sectional schematic view of a GaN layer manufacturing apparatus according to a fifth embodiment.

Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that in the following embodiments, identical or equivalent parts will be denoted by the same reference numerals.

(First embodiment)
A first embodiment will be described with reference to the drawings. First, the configuration of a GaN layer manufacturing apparatus will be described with reference to Fig. 1. The GaN layer manufacturing apparatus shown in Fig. 1 is installed with the top and bottom directions of the paper on which Fig. 1 is drawn, and grows a GaN layer 122 on a seed substrate 121.

As shown in FIG. 1, the GaN layer manufacturing apparatus includes a growth apparatus 10 that grows the GaN layer 122, and a generation apparatus 20 that generates gallium trichloride gas as a source gas for growing the GaN layer 122. The GaN layer manufacturing apparatus also includes first to fifth supply pipes 310 to 350 that supply various gases for growing the GaN layer 122 to the growth apparatus 10.

The growth apparatus 10 includes a growth vessel 100, a heating vessel 110, a base 120, a shaft 131, a rotational displacement mechanism 132, a heating device 140, etc.

The growth vessel 100 has a cylindrical tube portion 101 with a hollow portion 101a that forms a reaction chamber, and a first lid portion 102 and a second lid portion 103 that are attached to the tube portion 101 and close the hollow portion 101a. The tube portion 101 is made of quartz glass or the like and is cylindrical in this embodiment. The first lid portion 102 and the second lid portion 103 are made of SUS or the like, with the first lid portion 102 attached to one end of the tube portion 101 that is the top side, and the second lid portion 103 attached to the other end of the tube portion 101 that is the bottom side. The growth vessel 100 has a structure in which other components for growing the GaN layer 122 are placed within the hollow portion 101a, and the pressure in this hollow portion 101a can be reduced by evacuating it.

The growth vessel 100 is also provided with first to fifth supply pipes 310 to 350 that supply various gases for growing the GaN layer 122. In this embodiment, the first lid 102 is provided with the first to fifth supply pipes 310 to 350. Specifically, the first lid 102 is provided with a first supply pipe 310 that supplies gallium trichloride gas into the growth vessel 100 as a gallium-based gas for growing the GaN layer 122 generated by the generation device 20. The first lid 102 is provided with a second supply pipe 320 that supplies ammonia gas into the growth vessel 100 as an ammonia-based gas for growing the GaN layer 122 together with the gallium trichloride gas. The first lid 102 is provided with a third supply pipe 330 that supplies a dopant gas into the growth vessel 100. The first lid 102 is provided with a fourth supply pipe 340 that supplies nitrogen gas as a carrier gas into the growth vessel 100. In this embodiment, hydrogen gas is also supplied to the fourth supply pipe 340 along with nitrogen gas as a carrier gas. The first lid 102 is also provided with a fifth supply pipe 350 that supplies chlorine gas as an etching gas into the growth vessel 100. The fifth supply pipe 350, through which chlorine gas is supplied, is formed, for example, of a pipe with a corrosion-resistant fluorine coating. In this embodiment, chlorine gas is also supplied to the first supply pipe 310, as described below, and therefore the first supply pipe 310 is also formed of a pipe with a corrosion-resistant fluorine coating. In this embodiment, the first supply pipe 310 and the fifth supply pipe 350 correspond to etching gas supply pipes.

In this embodiment, the first to fifth supply pipes 310 to 350 are arranged so that one end is located within the heating container 110, which will be described later. However, the fourth and fifth supply pipes 330 are arranged so that one end is located closer to the first lid 102 than one end of the first to third supply pipes 310 to 330. In other words, the fourth supply pipe 340 is arranged so that the gas supplied from the first to third supply pipes 310 to 330 is easily caused to flow downward (i.e., toward the seed substrate 121, which will be described later) by the gas supplied from the fourth supply pipe 340. Furthermore, the fifth supply pipe 350 is arranged so that chlorine gas can easily reach the first lid 102 side as well.

The first supply pipe 310 has one end connected to the growth apparatus 10 and the other end opposite the growth apparatus 20. In other words, the first supply pipe 310 is arranged to connect the growth apparatus 10 and the generation apparatus 20. The first supply pipe 310 also has a smaller cross-sectional area normal to the gas flow direction than the generation vessel 200, which will be described later. Although not specifically shown, the second to fifth supply pipes 320 to 350 have their other ends opposite the one end of the growth apparatus 10 connected to their respective gas supply sources.

Furthermore, the growth vessel 100 is provided with an exhaust port 104 for discharging exhaust gases including unreacted gases that did not contribute to the growth of the GaN layer 122. In this embodiment, the exhaust port 104 is provided in the portion of the growth vessel 100 on the second lid 103 side.

The heating container 110 is made of, for example, alumina, zirconia, pyrolytic carbon, graphite, or the like, and is formed in a cylindrical shape with a hollow portion 110a. The heating container 110 is attached to the first lid portion 102 so that various gases from the first to fifth supply pipes 310 to 350 are supplied into the hollow portion 110a.

The pedestal 120 is a component on which a seed substrate 121 made of GaN is placed for growing a GaN layer 122, and is positioned below the heating vessel 110. The pedestal 120 is made of a material that is resistant to thermal etching, such as graphite coated with a high-melting-point metal carbide such as PbN, SiC, TaC, or NbC. The seed substrate 121 is attached to one surface 120a of the pedestal 120 that faces the first to fifth supply pipes 310 to 350, and the GaN layer 122 is grown on the surface of the seed substrate 121.

In this embodiment, as described below, the GaN layer 122 is grown by supplying gallium chloride gas and ammonia gas onto the seed substrate 121. It has been reported that when gallium chloride gas is used to grow the GaN layer 122, the GaN layer 122 grows easily whether the growth surface of the seed substrate 121 is the nitrogen face or the gallium face. Therefore, in this embodiment, the desired face of the seed substrate 121 can be selected as the growth surface for the GaN layer 122.

However, the GaN layer 122 may also be grown by supplying gallium trichloride gas and ammonia gas onto the seed substrate 121. In this case, it has been reported that when gallium trichloride gas is used to grow the GaN layer 122, the GaN layer 122 grows more easily if the growth surface of the seed substrate 121 is the nitrogen face, but grows less easily if the growth surface of the seed substrate 121 is the gallium face. Therefore, when growing the GaN layer 122 by supplying gallium trichloride gas and ammonia gas onto the seed substrate 121, it is preferable to position the seed substrate 121 so that the growth surface of the GaN layer 122 is the nitrogen face. In other words, it is preferable to position the seed substrate 121 so that the surface opposite the pedestal 120 is the nitrogen face.

A shaft 131 is connected to the surface of the pedestal 120 opposite the surface on which the seed substrate 121 is placed. The pedestal 120 is rotated in conjunction with the rotation of the shaft 131, and is displaced together with the shaft 131 as it moves along the axial direction of the growth vessel 100 (i.e., the vertical direction in the plane of the page in Figure 1). Like the pedestal 120, the shaft 131 is made of a material that is resistant to thermal etching, such as graphite coated on its surface with a high-melting-point metal carbide such as PbN, SiC, TaC, or NbC.

The rotational displacement mechanism 132 is a component that includes gears, a motor, etc., and is connected to the shaft 131 to rotate and displace the shaft 131. When displacing the shaft 131, the rotational displacement mechanism 132 displaces the shaft 131 (i.e., the seed substrate 121) so that the temperature of the growth surface of the GaN layer 122 becomes suitable for growth as the GaN layer 122 grows. Furthermore, when growing the GaN layer 122, the rotational displacement mechanism 132 of this embodiment rotates the shaft 131 so that the pedestal 120 rotates at least 200 revolutions per minute, although this is not a particular limitation. In this embodiment, the rotational displacement mechanism 132 corresponds to the rotation mechanism.

The heating device 140 heats the heating vessel 110 and the inside of the growth vessel 100. It is composed of a heating coil, such as an induction heating coil or a direct heating coil, and is arranged to surround the periphery of the growth vessel 100. In this embodiment, the heating device 140 is driven so that, when growing the GaN layer 122, the temperature around the seed substrate 121 reaches approximately 1000 to 1300°C and the temperature inside the heating vessel 110 reaches 700°C or higher.

The generation device 20 includes a generation vessel 200 and a heating device 240. The generation vessel 200 includes a cylindrical tube portion 201 having a hollow portion 201a, and a first lid portion 202 and a second lid portion 203 provided on the tube portion 201 and closing the hollow portion 201a. The tube portion 201 is made of quartz glass or the like, and in this embodiment, is cylindrical. The first lid portion 202 and the second lid portion 203 are made of SUS or the like. The first lid portion 202 is provided at the end of the tube portion 201 opposite the side to which the first supply pipe 310 is connected, and the second lid portion 203 is provided at the end of the tube portion 201 to which the first supply pipe 310 is connected. Similar to the growth vessel 100, the generation vessel 200 is designed so that the pressure in the hollow portion 201a can be reduced by vacuuming.

The production vessel 200 is provided with a partition wall 213 that divides the hollow portion 201a into a first space 211 on the first lid portion 202 side and a second space 212 on the second lid portion 203 side. However, this partition wall 213 is formed so as to maintain communication between the first space 211 and the second space 212. In other words, the partition wall 213 is configured so as not to completely separate the first space 211 from the second space 212.

Metallic gallium 220 is placed in the first space 211. In this embodiment, the second space 212 is provided with a partition wall 214 to increase the wall surface that comes into contact with the gallium monochloride gas and chlorine gas generated in the first space 211, as described below.

The generation vessel 200 is also equipped with a first induction pipe 231 and a second induction pipe 232 that guide chlorine gas into the generation vessel 200. In this embodiment, the first induction pipe 231 is provided in the first lid portion 202 so that chlorine gas can be guided to the first space 211. The second induction pipe 232 is provided in the cylindrical portion 201 so that chlorine gas can be guided to the second space 212. In this embodiment, nitrogen gas is also guided into the generation vessel 200 as a carrier gas from the first induction pipe 231 and the second induction pipe 232.

The heating device 240 heats the inside of the production vessel 200 and is configured, for example, by a resistance heater, and is arranged around the production vessel 200. In this embodiment, the heating device 240 is arranged to surround the portion of the production vessel 200 that constitutes the first space 211. When growing the GaN layer 122, the heating device 240 is driven so that the first space 211 is approximately 800 to 900°C and the temperature of the second space 212 on the second lid portion 203 side is approximately 150°C due to heat transfer from the first space 211. Note that, because the second space 212 in this embodiment is heated by heat transfer from the first space 211, a temperature gradient results in the temperature gradually decreasing from the portion on the first space 211 side toward the second lid portion 203 side.

The other end of the first supply pipe 310 is provided on the second lid 203 of the generation device 20. Although not specifically shown, a heating device is also arranged around the first supply pipe 310. The first supply pipe 310 is heated to, for example, approximately 150°C when growing the GaN layer 122.

The above is the configuration of the GaN layer manufacturing apparatus in this embodiment. Next, we will explain the method for manufacturing the GaN layer 122 using the above GaN layer manufacturing apparatus.

First, the GaN layer manufacturing apparatus is prepared, and the seed substrate 121 is placed on one surface 120a of the pedestal 120. Then, the rotational displacement mechanism 132 rotates the pedestal 120 via the shaft 131, and the position of the pedestal 120 is adjusted. Note that while the GaN layer 122 is growing, the height of the pedestal is adjusted to match the growth rate of the GaN layer 122. This keeps the height of the growth surface of the GaN layer approximately constant, making it possible to effectively control the temperature distribution of the growth surface temperature.

Next, the heating devices 140, 240 are driven. Specifically, the heating device 140 is driven so that the temperature around the seed substrate 121 placed in the growth vessel 100 reaches approximately 1000-1300°C and the temperature inside the heating vessel 110 reaches 700°C or higher. The heating device 240 is also driven so that the first space 211 in the generation vessel 200 reaches approximately 800-900°C and the portion of the second space 212 on the second lid 203 side reaches approximately 150°C. Furthermore, although not shown, the heating devices arranged around the first supply pipe 310 are driven so that the first supply pipe 310 also reaches approximately 150°C.

Next, chlorine gas and nitrogen gas as a carrier gas are introduced into the generator 20 from the first induction pipe 231 and the second induction pipe 232. As a result, in the first space 211, the metallic gallium 220 reacts with the chlorine gas to generate gallium monochloride gas, as shown in the following chemical formula 1.

(Chemical formula 1) Ga + 1/2Cl ₂ → GaCl
Furthermore, as this gallium monochloride gas flows into the second space 212, the gallium monochloride gas reacts with the chlorine gas introduced into the second space 212 to produce gallium trichloride gas, as shown in Chemical Formula 2 below.

(Chemical formula 2) GaCl+Cl ₂ →GaCl ₃
At this time, residual gallium monochloride can be suppressed by making the amount of chlorine gas derived from the second supply pipe 320 greater than the amount of chlorine gas derived from the first supply pipe 310. Although not particularly limited, for example, about 100 sccm of chlorine gas is derived from the first supply pipe 310, and about 200 sccm of chlorine gas is derived from the second supply pipe 320. Note that, for example, about 1 slm of nitrogen gas is derived.

Then, gallium trichloride gas is supplied to the growth apparatus 10 via the first supply pipe 310. In this case, the second space 212 in this embodiment is provided with a partition wall 214. Therefore, the gas guided into the second space 212 is more likely to collide with the partition wall 214, which serves as a high-temperature portion, and the flow distance is longer. This prevents gallium monochloride gas from remaining without reacting with chlorine gas. Note that gallium trichloride has a lower boiling point than gallium monochloride, and gallium trichloride gas is more difficult to solidify than gallium monochloride gas. Therefore, by supplying gallium trichloride gas to the growth apparatus 10 from the first supply pipe 310 in this manner, it is possible to prevent gallium monochloride gas from solidifying in the first supply pipe 310 and clogging the first supply pipe 310.

Ammonia gas is then supplied to the growth vessel 100 from the second supply pipe 320, and nitrogen gas and hydrogen gas are supplied to the growth vessel 100 from the fourth supply pipe 340. At this time, gallium monochloride is produced in the heating vessel 110 according to the following chemical formula 3.

(Chemical formula 3) GaCl ₃ +H ₂ →GaCl+2HCl
Thereafter, ammonia gas and gallium monochloride gas are flowed and supplied to seed substrate 121, and GaN layer 122 is grown on the surface of seed substrate 121 as shown in Chemical Formula 4 below.

(Chemical formula 4) GaCl+NH ₃ →GaN+HCl+H ₂
The supply of ammonia gas is preferably started after the heating device 140 is driven, when the temperature around the seed substrate 121 is 500° C. or lower, in order to prevent nitrogen loss. The ammonia gas is supplied at, for example, about 1 to 5 slm. The nitrogen gas serving as a carrier gas is supplied at, for example, about 1 to 10 slm. The hydrogen gas is supplied at, for example, 50 to 500 sccm.

In this embodiment, as shown in Figure 2, the following GaN layers 122 are grown on the seed substrate 121 in this order: an n-GaN layer 122a doped with n-type impurities, an undoped u-GaN layer 122b not doped with impurities, and a p-GaN layer 122c doped with p-type impurities.

In this case, when the n-GaN layer 122a is grown by the reaction of Chemical Formula 4 above, a dopant gas containing n-type impurities is supplied to the growth apparatus 10 from the third supply pipe 330 in addition to gallium chloride gas and ammonia gas. Similarly, when the p-GaN layer 122c is grown by the reaction of Chemical Formula 4 above, a dopant gas containing p-type impurities is supplied to the growth apparatus 10 from the third supply pipe 330 in addition to gallium chloride gas and ammonia gas. An example of a dopant gas containing n-type impurities is a gas containing ((C ₂ H ₅ ) ₃ SiH), and an example of a dopant gas containing p-type impurities is a gas containing Mg, Cp ₂ Mg, or MgCl ₂ .

The u-GaN layer 122b is grown by supplying gallium monochloride gas and ammonia gas to the seed substrate 121 while stopping the supply of dopant gas from the third supply pipe 330.

As described above, when the n-GaN layer 122a, which is a doped GaN layer, is grown, there is a possibility that foreign matter caused by impurities will adhere to the inner wall surface of the growth vessel 100. Therefore, when the u-GaN layer 122b, which is an undoped GaN layer, is grown after the n-GaN layer 122a, there is a possibility that impurities will be mixed into the u-GaN layer 122b.

Therefore, in this embodiment, after growing the n-GaN layer 122a, a foreign matter removal process is performed to remove foreign matter adhering to the inner wall surfaces, etc., of the growth apparatus 10. Specifically, first, gallium trichloride gas is prevented from being supplied from the first supply pipe 310 into the growth vessel 100. In this embodiment, chlorine gas introduced from the first induction pipe 231 in the generation apparatus 20 is stopped. As a result, gallium monochloride gas is not generated in the first space 211 of the generation apparatus 20, and therefore gallium trichloride gas is no longer supplied from the first supply pipe 310 into the growth vessel 100.

Next, chlorine gas is supplied into the growth apparatus 10. In this embodiment, the chlorine gas that was being introduced into the second space 212 of the generation apparatus 20 continues to be introduced, and chlorine gas is introduced into the growth apparatus 10 from the first supply pipe 310. In this embodiment, chlorine gas is also supplied into the growth apparatus 10 from the fifth supply pipe 350. As chlorine gas is an etching gas, this makes it possible to remove foreign matter adhering to the inner wall surface of the growth vessel 100. Note that by introducing chlorine gas from the first supply pipe 310 into the growth apparatus 10, gallium monochloride and the like that may be adhering to the first supply pipe 310 can also be removed.

Furthermore, in this embodiment, when the foreign matter removal process is performed, the supply of ammonia gas from the second supply pipe 320 continues. This causes ammonia gas to be present on the GaN layer 122 grown before the foreign matter removal process is performed, making it difficult for chlorine gas to reach the GaN layer 122. Therefore, it is possible to prevent the grown GaN layer 122 from being etched by chlorine gas.

Furthermore, in this embodiment, when performing the foreign matter removal process, the rotation speed of the pedestal 120 (i.e., the seed substrate 121) is set lower than when growing the GaN layer 122. For example, when performing the foreign matter removal process, the shaft 131 is rotated so that the pedestal 120 rotates several tens of times per minute. This makes it difficult for chlorine gas to be drawn into the periphery of the pedestal 120, making it difficult for the chlorine gas to reach the GaN layer 122. Therefore, it is possible to prevent the grown GaN layer 122 from being etched by chlorine gas.

The u-GaN layer 122b is then grown after a foreign material removal process. This prevents impurities from being introduced into the u-GaN layer 122b during growth of the n-GaN layer 122a.

Note that the p-GaN layer 122c is grown directly after the u-GaN layer 122b is grown, since no dopant gas is supplied when growing the u-GaN layer 122b.

According to the present embodiment described above, when growing a doped GaN layer as the GaN layer 122 and then growing an undoped GaN layer, a foreign matter removal process is performed before growing the undoped GaN layer. This prevents foreign matter from being mixed into the undoped GaN layer, and prevents changes in the properties of the GaN layer 122.

In addition, the foreign matter removal process prevents impurities from being mixed into the undoped GaN layer, eliminating the need to place an adsorption layer between the doped and undoped GaN layers. This makes it less likely that lattice mismatches caused by the placement of an adsorption layer will occur, and prevents distortion of the grown GaN layer 122.

In this embodiment, an example has been described in which an n-GaN layer 122a is grown as a doped GaN layer, followed by a u-GaN layer 122b as an undoped GaN layer. However, the manufacturing apparatus and manufacturing method of this embodiment can also be applied to the following cases. For example, when growing a high-impurity-concentration n-type first GaN layer as a doped GaN layer and then a low-impurity-concentration n-type second GaN layer, if the second GaN layer is grown directly after the first GaN layer is grown, there is a possibility that the impurity concentration of the second GaN layer will change due to the inclusion of foreign matter adhering to the growth apparatus 10. Therefore, by growing the first GaN layer and then performing a foreign matter removal process before growing the second GaN layer, changes in the impurity concentration of the second GaN layer can be suppressed. In other words, the manufacturing apparatus and manufacturing method of this embodiment can be applied when GaN layers with different impurity types or impurity concentrations are grown in sequence, and by performing a foreign matter removal process before growing the subsequent GaN layer, changes in the properties of the GaN layer can be suppressed.

(1) In this embodiment, when the foreign matter removal process is performed, ammonia gas is continuously supplied from the second supply pipe 320. This makes it difficult for chlorine gas to reach the grown GaN layer 122, thereby preventing the GaN layer 122 from being etched.

(2) In this embodiment, when performing the foreign matter removal process, the rotation speed of the pedestal 120 (i.e., the seed substrate 121) is set lower than when growing the GaN layer 122. This makes it difficult for chlorine gas to be drawn into the periphery of the pedestal 120, making it difficult for the chlorine gas to reach the GaN layer 122. This prevents the GaN layer 122 from being etched by the chlorine gas.

(Modification of the first embodiment)
In the first embodiment, an example has been described in which chlorine gas is supplied to the growth apparatus 10 from the first supply pipe 310 and the fifth supply pipe 350 during the foreign matter removal process, but chlorine gas may be supplied from only one of them. Note that if chlorine gas is introduced into the growth apparatus 10 from only the first supply pipe 310, the fifth supply pipe 350 may not be provided.

Second Embodiment
A second embodiment will be described. This embodiment is different from the first embodiment in that an exhaust port 104 is added. As the rest of the configuration is the same as the first embodiment, a description thereof will be omitted here.

In the GaN layer manufacturing apparatus of this embodiment, as shown in FIG. 3, an exhaust port 104 is also provided on the portion of the growth vessel 100 on the first lid 102 side. Hereinafter, the exhaust port 104 provided on the second lid 103 side will be referred to as the lower exhaust port 104a, and the exhaust port 104 provided on the first lid 102 side will be referred to as the upper exhaust port 104b. In this embodiment, the lower exhaust port 104a corresponds to the first exhaust port, and the upper exhaust port 104b corresponds to the second exhaust port.

In addition, in this embodiment, the lower exhaust port 104a is equipped with a lower opening/closing unit (not shown), and the upper exhaust port 104b is equipped with an upper opening/closing unit (not shown). The lower opening/closing unit and the upper opening/closing unit are each composed of a valve or the like, and when opened, they connect the inside of the growth vessel 100 to the outside, and when closed, they block communication between the inside of the growth vessel 100 and the outside.

The above is the configuration of the GaN layer manufacturing apparatus in this embodiment. Next, we will explain the method for manufacturing the GaN layer 122 using the above GaN layer manufacturing apparatus.

In this embodiment, when growing the GaN layer 122, the lower opening/closing unit is opened and the upper opening/closing unit is closed. In other words, the inside and outside of the growth apparatus 10 are in communication with each other through the lower exhaust port 104a, but the inside and outside of the growth apparatus 10 are not in communication with each other through the upper exhaust port 104b. As a result, exhaust gases used when growing the GaN layer 122 are exhausted from the lower exhaust port 104a.

On the other hand, when performing the foreign matter removal process, the lower opening/closing unit is closed and the upper opening/closing unit is open. In other words, the inside and outside of the growth apparatus 10 are in communication with each other through the upper exhaust port 104b, while the inside and outside of the growth apparatus 10 are not in communication with each other through the lower exhaust port 104a. As a result, the exhaust gas (i.e., chlorine gas) used during the foreign matter removal process is exhausted from the upper exhaust port 104b. This allows for efficient removal of foreign matter located on the first lid 102 side of the seed substrate 121. In other words, it allows for efficient removal of foreign matter that may reach the seed substrate 121. Therefore, when growing the GaN layer 122 after the foreign matter removal process, it is possible to further prevent foreign matter from being mixed into the GaN layer 122.

According to the present embodiment described above, the foreign matter removal process is performed without an adsorption layer, so the same effects as those of the first embodiment can be obtained.

(1) In this embodiment, an upper exhaust port 104b is provided. When performing the foreign matter removal process, exhaust gas is exhausted from the upper exhaust port 104b. This allows foreign matter located on the first lid 102 side of the seed substrate 121 to be efficiently removed, and further prevents foreign matter from being mixed into the GaN layer 122 when the GaN layer 122 is grown after the foreign matter removal process.

(Third embodiment)
A third embodiment will be described. This embodiment is different from the first embodiment in that a shielding plate is added. As the other features are the same as those of the first embodiment, a description thereof will be omitted here.

In the GaN layer manufacturing apparatus of this embodiment, as shown in FIG. 4, the growth apparatus 10 is provided with a displaceable shielding plate 150. Specifically, the shielding plate 150 is provided so that it can be switched between a displaced state in which it is positioned between the heating vessel 110 and the seed substrate 121, and a stored state in which it is positioned at a position different from between the heating vessel 110 and the seed substrate 121. The displaced state is, in other words, a state in which the shielding plate 150 is positioned between one end of the first and fifth supply pipes 310, 350 and the seed substrate 121. The stored state is, in other words, a state in which the shielding plate 150 is not positioned between the heating vessel 110 and the seed substrate 121. Figure 4 shows the shielding plate 150 in the displaced state.

The above is the configuration of the GaN layer manufacturing apparatus in this embodiment. Next, we will explain the method for manufacturing the GaN layer 122 using the above GaN layer manufacturing apparatus.

In this embodiment, when growing the GaN layer 122, the shielding plate 150 is positioned in a retracted state. This prevents the shielding plate 150 from interfering with the flow of each gas supplied into the heating vessel 110.

Then, when the foreign matter removal process is performed, the shielding plate 150 is displaced. That is, when performing the foreign matter removal process, the shielding plate 150 is positioned between the first and fifth supply pipes 310, 350 and the seed substrate 121. This prevents chlorine gas from reaching the GaN layer 122, and prevents the GaN layer 122 from being etched. Note that in this embodiment, the shielding plate 150 makes it difficult for chlorine gas to reach the GaN layer 122. Therefore, when performing the foreign matter removal process, ammonia gas does not need to be supplied from the second supply pipe 320. Furthermore, when performing the foreign matter removal process, it is not necessary to reduce the rotation speed of the pedestal 120.

According to the present embodiment described above, the foreign matter removal process is performed without an adsorption layer, so the same effects as those of the first embodiment can be obtained.

(1) In this embodiment, a shielding plate 150 is provided, and the shielding plate 150 is displaced when performing the foreign matter removal process. This prevents chlorine gas from reaching the GaN layer 122, thereby preventing the GaN layer 122 from being etched.

(Fourth embodiment)
A fourth embodiment will be described. In this embodiment, a sixth supply pipe is connected to the first supply pipe 310 in comparison with the first embodiment. As the rest of the configuration is the same as the first embodiment, a description thereof will be omitted here.

In the GaN layer manufacturing apparatus of this embodiment, as shown in FIG. 5, the first supply pipe 310 is provided with a sixth supply pipe 360 via a switching unit 400 composed of a valve or the like. The end of the sixth supply pipe 360 opposite the switching unit 400 is connected to a gas supply source (not shown) so that nitrogen gas is supplied as a carrier gas. Then, by adjusting the switching unit 400, the growth apparatus 10 is supplied with gallium trichloride gas from the generation apparatus 20 or nitrogen gas from the sixth supply pipe 360.

The above is the configuration of the GaN layer manufacturing apparatus in this embodiment. Next, we will explain the method for manufacturing the GaN layer 122 using the above GaN layer manufacturing apparatus.

In this embodiment, when growing the GaN layer 122, the switching unit 400 is adjusted so that gallium trichloride gas is supplied from the generation device 20 to the growth device 10.

On the other hand, when performing the foreign matter removal process, chlorine gas is supplied to the growth apparatus 10 from the fifth supply pipe 350, and chlorine gas is not supplied from the generation device 20 to the growth apparatus 10 via the first supply pipe 310. If the supply of gas from the first supply pipe 310 to the growth apparatus 10 is stopped at this time, the amount and flow of gas within the growth apparatus 10 may change, making it difficult to subsequently grow the GaN layer 122. Therefore, in this embodiment, when performing the foreign matter removal process, the switching unit 400 is adjusted so that nitrogen gas is supplied to the growth apparatus 10 from the sixth supply pipe 360. This prevents changes in the amount and flow of gas within the growth apparatus 10.

According to the present embodiment described above, the foreign matter removal process is performed without an adsorption layer, so the same effects as those of the first embodiment can be obtained.

(1) In this embodiment, when performing the foreign matter removal process, chlorine gas is supplied to the growth apparatus 10 from the fifth supply pipe 350, and chlorine gas is not supplied from the generation device 20 to the growth apparatus 10 via the first supply pipe 310. Furthermore, when performing the foreign matter removal process, the switching unit 400 is adjusted so that nitrogen gas is supplied to the growth apparatus 10 from the sixth supply pipe 360. This prevents changes in the amount and flow of gas within the growth apparatus 10 and prevents subsequent difficulties in growing the GaN layer 122.

Fifth Embodiment
A fifth embodiment will be described. This embodiment is different from the first embodiment in that a storage chamber is added. As the rest of the configuration is the same as the first embodiment, a description thereof will be omitted here.

As shown in FIG. 6, the GaN layer manufacturing apparatus of this embodiment is equipped with a storage chamber 30 in addition to a growth apparatus 10 and a generation apparatus 20. The storage chamber 30 stores a seed substrate 121 or a wafer with a GaN layer 122 grown on the seed substrate 121, and, like the growth vessel 100, is made of quartz glass or the like and is box-shaped.

A heating device 31, which is composed of a heating coil such as an induction heating coil or a direct heating coil, is arranged around the periphery of the growth vessel 100 around the periphery of the accommodation chamber 30. In this embodiment, the heating device 31 is driven so that the temperature inside the accommodation chamber 30 is approximately 1000 to 1300°C. In other words, the heating device 31 is driven so that the temperature inside the accommodation chamber 30 is the same as the temperature around the seed substrate 121 when the GaN layer 122 is grown. Note that in this embodiment, the "temperature inside the accommodation chamber 30 being the same as the temperature around the seed substrate 121" includes a margin of error, and includes, for example, a case where the temperature inside the accommodation chamber 30 is approximately ±20% of the temperature around the seed substrate 121 when the GaN layer 122 is grown.

The storage chamber 30 is also equipped with a supply pipe 32 for supplying ammonia gas into the storage chamber 30, as well as an exhaust port 33 for exhaust.

The storage chamber 30 is connected to the growth device 10 via a transport passage 40. The transport passage 40 is also equipped with an openable and closable partition door 41. The growth device 10 and the storage chamber 30 are in communication when the partition door 41 is open, and are separated when the partition door 41 is closed.

Furthermore, although not specifically shown, the GaN layer manufacturing apparatus of this embodiment is equipped with a transport unit capable of transporting the seed substrate 121 between the growth apparatus 10 and the accommodation chamber 30 through the transport passage 40. The transport unit is capable of transporting the seed substrate 121 from the accommodation chamber 30 into the growth apparatus 10, and transporting the seed substrate 121 on which the GaN layer 122 has been grown from the growth apparatus 10 into the accommodation chamber 30.

The above is the configuration of the GaN layer manufacturing apparatus in this embodiment. Next, we will explain the method for manufacturing the GaN layer 122 using the above GaN layer manufacturing apparatus.

In this embodiment, the GaN layer 122 is grown on the seed substrate 121 by appropriately performing the GaN layer 122 growth process and the foreign matter removal process. Note that the partition door 41 is closed when growing the GaN layer 122. The accommodation chamber 30 is heated to approximately 1000-1300°C by the heating device 31 and is adjusted to be filled with ammonia gas.

After the GaN layer 122 has been grown, the partition door 41 is opened, and the seed substrate 121 on which the GaN layer 122 has been grown is transported to and accommodated in the accommodation chamber 30. A new seed substrate 121 is then transported from the accommodation chamber 30 into the growth apparatus 10 and placed on the pedestal 120. In this embodiment, the accommodation chamber 30 is heated to approximately 1000-1300°C and filled with ammonia gas. Therefore, when the partition door 41 is opened, significant changes in the conditions inside the growth apparatus 10 can be prevented, facilitating the subsequent growth of the GaN layer 122.

According to the present embodiment described above, the foreign matter removal process is performed without an adsorption layer, so the same effects as those of the first embodiment can be obtained.

(1) In this embodiment, a storage chamber 30 is provided, which is connected to the growth apparatus 10 via a transfer passage 40. The seed substrate 121 on which the GaN layer 122 has been grown is transferred to and stored in the storage chamber 30, and a new seed substrate 121 is transferred from the storage chamber 30 into the growth apparatus 10 and placed on the pedestal 120, allowing GaN layers 122 to be continuously grown on the different seed substrates 121. This reduces the manufacturing time when GaN layers 122 are grown on multiple different seed substrates 121.

The accommodation chamber 30 is heated to approximately 1000-1300°C and is adjusted to be filled with ammonia gas. This prevents significant changes in the conditions inside the growth apparatus 10 when the seed substrate 121 is transported, facilitating the subsequent growth of the GaN layer 122.

(Other embodiments)
Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

In each of the above embodiments, the configuration of the growth apparatus 10 may be modified as appropriate. For example, in each of the above embodiments, an example was described in which a rotational displacement mechanism 132 was provided to rotate and displace the pedestal 120, but it is also possible to only rotate the pedestal 120 without displacing it.

Furthermore, in each of the above embodiments, the second space 212 does not necessarily need to be provided with a partition wall 214.

Furthermore, in the first embodiment described above, when the foreign matter removal process is performed, it is possible to either continue the supply of ammonia gas or reduce the rotation speed of the base 120. Furthermore, in the first embodiment described above, when the foreign matter removal process is performed, it is possible to neither continue the supply of ammonia gas nor reduce the rotation speed of the base 120.

Furthermore, in each of the above embodiments, the other end of the first supply pipe 310 may be connected to a gas supply source different from the generation apparatus 20, and the gallium-based gas may be supplied to the growth apparatus 10 from this gas supply source.

Furthermore, in each of the above embodiments, hydrogen gas may not be supplied from the fourth supply pipe 340, and gallium trichloride gas may be supplied to the seed substrate 121. In this case, the gallium trichloride gas reacts with ammonia gas to grow the GaN layer 122.

The above embodiments can also be combined as appropriate. For example, the second embodiment can be combined with any of the third to fifth embodiments to include an upper exhaust port 104b. The third embodiment can be combined with any of the fourth and fifth embodiments to include a shielding plate 150. The fourth embodiment can be combined with the fifth embodiment to include a sixth supply pipe 360. Furthermore, combinations of the above embodiments can also be combined together.

REFERENCE SIGNS LIST 10 Growth apparatus 101a Hollow portion 100 Growth vessel 120 Pedestal 121 Seed substrate 122 GaN layer 231 First induction pipe 232 Second induction pipe 310 First supply pipe 320 Second supply pipe 330 Third supply pipe 350 Fifth supply pipe (etching gas supply pipe)

Claims (8)

A gallium nitride layer manufacturing apparatus for growing a gallium nitride layer (122) by supplying a gallium-based gas and an ammonia-based gas onto a seed substrate (121) made of gallium nitride,
a growth apparatus (10) having a cylindrical growth vessel (100) in which the gallium nitride layer is grown in a hollow portion (101a) that forms a reaction chamber;
a pedestal (120) disposed within the hollow portion of the growth chamber, on which the seed substrate on which the gallium nitride layer is grown is placed;
a first supply pipe (310) provided in the growth apparatus for supplying the gallium-based gas for growing the gallium nitride layer to the growth apparatus;
a second supply pipe (320) provided in the growth apparatus for supplying an ammonia-based gas for growing the gallium nitride layer;
a third supply pipe (330) provided in the growth apparatus for supplying a dopant gas to the growth apparatus;
an etching gas supply pipe (310, 350) provided in the growth apparatus for supplying an etching gas to the growth apparatus;
a gallium nitride layer manufacturing apparatus for growing a doped gallium nitride layer (122a) doped with impurities on the seed substrate by supplying the gallium-based gas, the ammonia-based gas, and the dopant gas, and then, before growing a gallium nitride layer (122b) different from the doped gallium nitride layer, the seed substrate on which the doped gallium nitride layer has been grown is placed on the pedestal, and the etching gas is supplied from the etching gas supply pipe to the growth apparatus to remove foreign matter adhering to the growth apparatus. The gallium nitride layer manufacturing apparatus of claim 1, wherein the ammonia-based gas is supplied from the second supply pipe when removing the foreign matter. a rotation mechanism (132) for rotating the base;
3. The gallium nitride layer manufacturing apparatus according to claim 1, wherein the rotation mechanism rotates the pedestal at a lower rotation speed when removing the foreign matter than when growing the gallium nitride layer. the first to third supply pipes and the etching gas supply pipe are provided on one end side of the growth chamber,
The growth vessel is provided with a first exhaust port (104a) at the other end opposite to the one end, and a second exhaust port (104b) at the one end,
4. The gallium nitride layer manufacturing apparatus according to claim 1, wherein exhaust gas is exhausted from the first exhaust port when growing the gallium nitride layer, and exhaust gas is exhausted from the second exhaust port when removing the foreign matter. The growth vessel is provided with a displaceable shielding plate (150),
5. The gallium nitride layer manufacturing apparatus according to claim 1, wherein the shielding plate is disposed between the seed substrate and the etching gas supply pipe when removing the foreign matter. the etching gas supply pipe is provided separately from the first supply pipe,
a sixth supply pipe (360) for supplying a carrier gas to the first supply pipe via a switching unit (400), and by adjusting the switching unit, it is possible to select between supplying the gallium-based gas and supplying the carrier gas to the growth apparatus;
6. The gallium nitride layer manufacturing apparatus according to claim 1, wherein when removing the foreign matter, the switching unit is adjusted so that the carrier gas is supplied to the growth apparatus. a storage chamber (30) for storing a plurality of the seed substrates;
a transfer passage (40) disposed between the growth apparatus and the accommodation chamber;
The growth apparatus and the storage chamber are separated by an openable and closable partition door (41) provided in the transport passage,
the accommodation chamber is adjusted to have the same temperature as the ambient temperature of the seed substrate when the gallium nitride layer is grown, and an ammonia-based gas is supplied to the accommodation chamber;
7. The gallium nitride layer manufacturing apparatus according to claim 1, wherein after the gallium nitride layer is grown on the seed substrate placed in the growth apparatus, the seed substrate placed in the growth apparatus is placed in the accommodation chamber, and a new seed substrate is placed in the growth apparatus from the accommodation chamber, and the gallium nitride layer is grown again on the new seed substrate. A method for manufacturing a gallium nitride layer, comprising: growing a gallium nitride layer (122) on a seed substrate (121) made of gallium nitride by supplying a gallium-based gas and an ammonia-based gas;
a growth apparatus (10) having a cylindrical growth vessel (100) in which the gallium nitride layer is grown in a hollow portion (101a) that forms a reaction chamber;
a pedestal (120) disposed within the hollow portion of the growth chamber, on which the seed substrate on which the gallium nitride layer is grown is placed;
a first supply pipe (310) provided in the growth apparatus for supplying the gallium-based gas for growing the gallium nitride layer to the growth apparatus;
a second supply pipe (320) provided in the growth apparatus for supplying an ammonia-based gas for growing the gallium nitride layer;
a third supply pipe (330) provided in the growth apparatus for supplying a dopant gas to the growth apparatus;
providing a gallium nitride layer production apparatus including an etching gas supply pipe (310, 350) provided in the growth apparatus and supplying an etching gas to the growth apparatus;
growing a doped gallium nitride layer (122a) doped with impurities on the seed substrate by supplying the gallium-based gas, the ammonia-based gas, and the dopant gas;
After growing the doped gallium nitride layer, supplying the etching gas to the growth apparatus while the seed substrate having the doped gallium nitride layer grown thereon is placed on the pedestal to remove foreign matter adhering to the growth apparatus;
After removing the foreign matter, growing a gallium nitride layer (122b) different from the doped gallium nitride layer.