JP2006173346A - Manufacturing method of organic metal gas phase growing device and semiconductor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method of an MOCVD device or a semiconductor layer, capable of preventing the depositing of reaction products on a region except a substrate and capable of growing a semiconductor with excellent reproducibility. <P>SOLUTION: The organic metal gas phase growing device is provided with a chamber 10 for retaining the substrate 1A on a susceptor 15 arranged therein, a cooling gas introducing port 2d provided from the wall unit of the chamber 10 to the inside of the chamber to introduce cooling gas into the chamber 10, process gas introducing ports 2a, 2b, provided from the wall unit of the chamber 10 to the inside of the same so as to be independent from the cooling gas introducing port 2d to introduce material gas into the chamber 10, and a process gas flow channel provided so as to be continuous from the process gas introducing ports 2a, 2b to carry the material gas introduced from the process gas introducing ports 2a, 2b onto the substrate 1A. The cooling gas introducing port 2d is installed at a position such that the cooling gas hits the outer wall of the process gas flow channel. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a metal organic vapor phase growth apparatus and a semiconductor manufacturing method using the apparatus, and more particularly to a method for growing a group III nitride semiconductor with good reproducibility.

  A group III nitride semiconductor such as GaN, AlN, InN, or a mixed crystal thereof such as AlGaN or InGaN is promising as a semiconductor material used for a light-emitting element, a light-receiving element, or a high-speed operation transistor in the visible to ultraviolet region.

  As an apparatus for growing a group III nitride semiconductor, a metal organic chemical vapor deposition (MOCVD) apparatus is often used. When a group III nitride semiconductor is grown using the MOCVD method, the group III nitride semiconductor is usually grown while heating the substrate at a high temperature of 1000 ° C. or higher. For this reason, members around the substrate in the reaction furnace are heated to a very high temperature. When a member heated to a high temperature exists, the raw material gas reacts with the member heated to the high temperature to generate a reaction product, and the reaction product adheres to the heated member.

  When such a reaction product adheres to, for example, a transparent quartz member provided for monitoring the substrate, there is a problem that the surface state or temperature during crystal growth cannot be monitored.

  In many cases, the reaction product is easily peeled off in the form of flakes, and there is a problem in that crystal growth is hindered by the peeled reaction product flying on the substrate.

  For these problems, the following first and second conventional examples have been proposed.

  First, the configuration of a semiconductor crystal film growth apparatus according to a first conventional example (see, for example, Patent Document 1) will be outlined with reference to FIG.

  As shown in FIG. 21, a substrate 100A is mounted on a susceptor 102 supported by a shaft 101 inside a reaction vessel 100, and a heater 103 for heating the substrate 100A is provided below the susceptor 102. Is installed. A reaction gas injection pipe 104 is installed on the side wall of the reaction vessel 100 so as to inject a reaction gas from the horizontal direction to the substrate 100A. In addition, a sub-injection tube 105 having an upper end protruding outward and a lower end tapered downward is installed on the upper wall portion of the reaction vessel 100. A light source 106 and a light sensor 107 are provided outside the reaction vessel 100. Further, the reaction vessel 100 is provided with an exhaust pump 108 for exhausting the internal gas.

  In the semiconductor crystal film growth apparatus according to the first conventional example having the above-described configuration, the reactive gas is injected from the horizontal direction toward the substrate 100A, and the substrate 100A is inactivated from the sub-injection tube 105. By injecting the gas, deposition of reaction products on the sub injection tube 105 can be prevented, and the surface state during crystal growth on the substrate can be monitored via the sub injection tube 105.

  The configuration of the semiconductor crystal film growth apparatus according to the second conventional example (see, for example, Patent Document 2) will be outlined with reference to FIG.

  As shown in FIG. 22, the reaction furnace is constituted by a double structure of an outer cylinder 200 having a branch portion and an inner cylinder 201. In addition, an inclined plate 201 a is provided in a part of the inner cylinder 201 on the upper side so that the gas flowing through the outer cylinder 200 can be introduced. In addition, two raw material supply pipes 202 are provided inside the inner cylinder 201. A susceptor 205 that is fixed to the rotating shaft 203 and includes a heater 204 is provided in a branch portion of the outer cylinder 200 located in the lower part and an opening provided in the inner cylinder 201.

In the semiconductor crystal film growth apparatus according to the second conventional example having the above-described configuration, a raw material gas is allowed to flow in the inner cylinder 201 and a purge gas is allowed to flow in the outer cylinder 200, so that the substrate 200A on the susceptor 205 is formed. In the vicinity, the purge gas flowing in the outer cylinder 200 is caused to flow into the inner cylinder 201, so that the source gas is pressed against the substrate 200A by the purge gas flowing into the inner cylinder 201 from the outer cylinder 200, so that growth tends to occur on the substrate 200A. Become. Thereby, the reaction product deposited on the inner wall of the inner cylinder 201 can be suppressed.
Japanese Patent Laid-Open No. 04-170390 Japanese Patent Laid-Open No. 10-167897

  However, in the structures of the first and second conventional examples described above, a so-called purge gas, which is a gas used to suppress the formation of reaction products, is mixed in the flow of a so-called carrier gas that is a reaction gas or a raw material gas. It has a structure that ends up. For this reason, the following problems arise.

  First, since the carrier gas and the purge gas cannot be controlled independently, there is a problem that it is very difficult to control the growth conditions. In particular, when a group III nitride semiconductor is grown, it is particularly difficult to control the growth conditions because the conditions of the carrier gas used differ depending on the mixed crystal layer to be grown. For example, when growing a group III nitride semiconductor, for example, when growing GaN, AlGaN or AlN, a carrier gas containing hydrogen as a main component is used, while when growing InGaN, for example, nitrogen is used as a main component. Use carrier gas. In addition, when growing AlGaN, trimethylaluminum (TMA) and ammonia, which are raw materials, cause a gas phase reaction before reaching the substrate and easily cause a polymerization reaction that does not contribute to the growth. By increasing the gas flow rate and increasing the flow velocity, the time required for the carrier gas to reach the substrate from the gas injection port is shortened to suppress the gas phase reaction. Thus, since it is necessary to change the component or flow rate of the carrier gas according to the type of the mixed crystal of the group III nitride semiconductor, the optimum purge gas condition also changes. For this reason, since it is necessary to control the carrier gas and the purge gas for each type of mixed crystal of the group III nitride semiconductor, it is very difficult to set the growth conditions, and it is very difficult to control the growth conditions.

  Further, since the purge gas made of an inert gas flows into the carrier gas, there is a problem that the ammonia partial pressure on the substrate cannot be increased.

  When growing a group III nitride semiconductor, it is necessary to increase the partial pressure of ammonia, which is a nitrogen source gas, because the efficiency of capturing nitrogen, which is a group V element, is poor. However, when the purge gas flows into the carrier gas, the ammonia partial pressure is lowered because ammonia is diluted by the purge gas on the substrate. In the case of using a large-sized apparatus for growing a large number of sheets, the ratio of the purge gas and ammonia to be mixed increases toward the downstream, so that the ammonia partial pressure decreases. For this reason, it is difficult to maintain a sufficient ammonia partial pressure for all the substrates.

  Therefore, when a group III nitride semiconductor is grown using an MOCVD apparatus, the apparatus is operated stably at a manufacturing level with good reproducibility, or using equipment that has been enlarged for production efficiency. There are situations where it is difficult to grow a large number of wafers or to grow on a large-area wafer.

  In view of the above, an object of the present invention is to provide an MOCVD apparatus or a semiconductor manufacturing method capable of preventing a reaction product from being deposited in a region other than a substrate and growing a semiconductor with good reproducibility. .

  In order to achieve the above object, a metal organic vapor phase epitaxy apparatus according to the present invention includes a chamber for holding a substrate on a susceptor disposed therein, a wall portion of the chamber extending from the inside to the inside, and a cooling gas in the chamber. The cooling gas introduction port for introducing the gas and the cooling gas introduction port are provided independently from the wall portion to the inside of the chamber so as to be continuous from the process gas introduction port and the process gas introduction port for introducing the raw material gas into the chamber. And a process gas flow channel that conveys the source gas introduced from the process gas inlet onto the substrate, and the cooling gas inlet is installed at a position where the cooling gas hits the outer wall of the process gas flow channel. It is characterized by.

  According to the metal organic vapor phase epitaxy apparatus according to the present invention, the process gas flow channel can be cooled by the cooling gas, so that the reaction product can be prevented from being deposited in the process gas flow channel. As a result, it is possible to provide a metal organic vapor phase epitaxy apparatus that can reduce the flying of the reaction product onto the substrate and can manufacture a semiconductor with good reproducibility.

  In the metal organic chemical vapor deposition apparatus according to the present invention, the process gas inlet has a first inlet for introducing a group V gas and a second inlet for introducing a group III gas. The inlet and the second inlet are preferably separated from each other up to the vicinity of the process gas flow channel.

  In this way, it is possible to suppress the gas phase reaction between the group V gas and the group III gas before reaching the vicinity of the substrate surface.

  In the organometallic vapor phase growth apparatus according to the present invention, it is preferable that the first inlet and the second inlet are installed in this order from the side closer to the susceptor.

  In this way, the group V gas introduced from the first inlet can be effectively supplied onto the substrate.

  In the organometallic vapor phase growth apparatus according to the present invention, the cooling gas inlet is preferably installed so as to overlap the process gas inlet.

  In this way, the process gas flow channel can be effectively cooled by the cooling gas introduced from the cooling gas inlet. Moreover, since the above-described effects can be realized with such a simple structure, the above-described effects can be stably obtained without being influenced by the assembly accuracy.

  The organometallic vapor phase growth apparatus according to the present invention preferably further includes a cooling gas flow channel provided so as to be continuous from the cooling gas inlet.

  In this way, the process gas flow channel can be effectively cooled by the cooling gas flow channel through which the cooling gas flows.

  In the metal organic chemical vapor deposition apparatus according to the present invention, the cooling gas flow channel is preferably installed so as to overlap the process gas flow channel.

  If it does in this way, since it becomes a structure where a cooling gas flow channel overlaps on a process gas flow channel, a process gas flow channel can be cooled effectively. Moreover, since the above-described effects can be realized with such a simple structure, the above-described effects can be stably obtained without being influenced by the assembly accuracy.

  In the metal organic chemical vapor deposition apparatus according to the present invention, the cooling gas flow channel is preferably made of quartz, and in this case, the cooling gas flow channel is prevented from being corroded by the group V gas used as the source gas. can do.

  In the metal organic chemical vapor deposition apparatus according to the present invention, the process gas flow channel is preferably made of quartz, and in this case, the process gas flow channel is prevented from being corroded by the group V gas used as the source gas. can do.

  In the metal organic chemical vapor deposition apparatus according to the present invention, the process gas inlet includes a first inlet for introducing a group V gas, a second inlet for introducing a group III gas, and a first inlet for introducing a pressure gas. It is preferable that the first inlet, the second inlet, and the third inlet are separated from each other up to the vicinity of the process gas flow channel.

  If it does in this way, since the density | concentration of V group gas and III group gas on a board | substrate can be effectively raised with press gas, the utilization efficiency of source gas can be improved. Further, it is possible to suppress the gas phase reaction between the group V gas and the group III gas before reaching the vicinity of the substrate surface.

  In the organometallic vapor phase growth apparatus according to the present invention, it is preferable that the first inlet, the second inlet, and the third inlet are installed in this order from the side closer to the susceptor.

  In this case, the group V gas introduced from the first inlet can be effectively supplied onto the substrate, and the pressing gas flows over the group V gas and the group III gas. The concentration of the group V gas and the group III gas in can be effectively increased.

  The organometallic vapor phase growth apparatus according to the present invention preferably further includes a heater for heating the substrate, and the heater has a structure divided into at least two or more.

  In this way, the temperature distribution in the susceptor that changes according to the type of gas used as the process gas or the type of gas used as the cooling gas can be adjusted uniformly. For this reason, a semiconductor having a uniform emission wavelength or composition distribution in the substrate plane can be grown on the substrate.

  In the metal organic chemical vapor deposition apparatus according to the present invention, the reason why the heater is preferably divided concentrically is that the temperature distribution in the susceptor depends on the type of gas used as the process gas or the type of gas used in the cooling gas. Accordingly, the distance from the center of the susceptor to the outside varies.

  In the metal organic vapor phase growth apparatus according to the present invention, it is preferable that each of the heaters controls electric power independently of each other.

  If it does in this way, it will become possible to adjust the temperature distribution in a susceptor uniformly.

  The metal organic vapor phase epitaxy apparatus according to the present invention preferably further includes an apparatus that is provided outside the chamber and that irradiates the substrate with light via a process gas flow channel.

  In the metal organic chemical vapor deposition apparatus according to the present invention, the light irradiation apparatus is preferably an apparatus for measuring a film thickness on the substrate.

  In the metal organic chemical vapor deposition apparatus according to the present invention, it is preferable that the light irradiation apparatus operates in synchronization with the rotation of the substrate.

  The metal organic vapor phase epitaxy apparatus according to the present invention preferably further includes a device that is provided outside the chamber and that measures infrared rays from the substrate or the susceptor via a process gas flow channel.

  In the metal organic chemical vapor deposition apparatus according to the present invention, the apparatus for measuring infrared rays is preferably an apparatus for measuring the temperature of the susceptor.

  In the semiconductor manufacturing method according to the present invention, a source gas introduced from a process gas introduction port provided on a substrate held on a susceptor disposed in a chamber from a wall portion of the chamber to an inside thereof is converted into a process gas. A semiconductor manufacturing method in which a semiconductor is grown on a substrate by being conveyed through a process gas flow channel provided continuously from an inlet, and a cooling gas introduced from a wall portion of the chamber to the inside The semiconductor is grown while the cooling gas introduced from the mouth is applied to the outer wall of the process gas flow channel.

  According to the semiconductor manufacturing method of the present invention, the process gas flow channel can be cooled by the cooling gas, so that the reaction product can be prevented from being deposited in the process gas flow channel. As a result, it is possible to provide a metal organic vapor phase epitaxy apparatus that can reduce the flying of the reaction product onto the substrate and can manufacture a semiconductor with good reproducibility.

  In the method for manufacturing a semiconductor according to the present invention, the source gas introduced from the process gas inlet includes a group III gas and a group V gas, and the group III gas and the group V gas reach the vicinity of the process gas flow channel. Are preferably introduced separately from each other.

  In this way, it is possible to suppress the gas phase reaction between the group V gas and the group III gas before reaching the vicinity of the substrate surface.

  In the semiconductor manufacturing method according to the present invention, the group III gas and the group V gas are preferably introduced separately in this order from the side close to the susceptor.

  In this way, the group V gas introduced from the first inlet can be effectively supplied onto the substrate.

  In the method for manufacturing a semiconductor according to the present invention, the group V gas preferably contains ammonia gas.

  If it does in this way, ammonia gas introduced from the 1st inlet can be supplied effectively on a substrate.

  In the semiconductor manufacturing method according to the present invention, it is preferable that the cooling gas is introduced into a cooling gas flow channel provided continuously from the cooling gas inlet and overlying the process gas flow channel.

  In this way, the process gas flow channel can be effectively cooled by the cooling gas flow channel through which the cooling gas flows.

  In the semiconductor manufacturing method according to the present invention, hydrogen gas having an excellent cooling effect can be used as the cooling gas.

  In the semiconductor manufacturing method according to the present invention, nitrogen gas may be used as the cooling gas. Nitrogen gas is effective when it is not preferable to use a cooling gas made of hydrogen gas depending on the semiconductor to be manufactured.

  In the semiconductor manufacturing method according to the present invention, when a group III nitride semiconductor not containing In is grown as a semiconductor, a cooling gas made of a gas containing hydrogen gas is used, and a group III nitride containing In as a semiconductor is used. When growing the semiconductor, it is preferable to use a cooling gas made of nitrogen gas.

  In this way, when growing a group III nitride semiconductor containing no In, which is hardly affected by hydrogen gas, the reaction product is deposited in the process gas flow channel using hydrogen gas with excellent cooling effect. In addition, when a group III nitride semiconductor containing In, which is greatly affected by hydrogen gas, is grown, by cooling with nitrogen gas, sufficient incorporation of In can be achieved. A nitride semiconductor can be grown.

  In the method for manufacturing a semiconductor according to the present invention, the source gas introduced from the process gas inlet includes a group III gas, a group V gas, and a pressing gas, and the group III gas, the group V gas, and the pressing gas are a process gas. It is preferable that they are introduced separately from each other up to the vicinity of the gas flow channel.

  If it does in this way, since the density | concentration of V group gas and III group gas on a board | substrate can be effectively raised with press gas, the utilization efficiency of source gas can be improved. Further, it is possible to suppress the gas phase reaction between the group V gas and the group III gas before reaching the vicinity of the substrate surface.

  In the semiconductor manufacturing method according to the present invention, the group III gas, the group V gas, and the pressing gas are preferably introduced separately in this order from the side close to the susceptor.

  In this case, the group V gas introduced from the first inlet can be effectively supplied onto the substrate, and the pressing gas flows over the group V gas and the group III gas. The concentration of the group V gas and the group III gas in can be effectively increased.

  In the method for manufacturing a semiconductor according to the present invention, the group V gas preferably contains ammonia gas.

  In this way, ammonia gas can be effectively supplied onto the substrate, and the pressure gas flows over the ammonia gas, so that the concentration of ammonia gas on the substrate can be effectively increased.

  In the method for manufacturing a semiconductor according to the present invention, when the pressure gas contains nitrogen gas, it is preferable for growing a group III nitride semiconductor.

  In the semiconductor manufacturing method according to the present invention, the heater provided for heating the substrate has a structure that is divided into at least a first heater and a second heater from the inside on a concentric circle, It is preferable to grow the semiconductor while changing the power applied to each of the first heater and the second heater in accordance with the proportion of hydrogen gas contained in the cooling gas.

  In this way, the temperature distribution in the susceptor that changes according to the type of gas used as the process gas or the type of gas used as the cooling gas can be adjusted uniformly. In particular, since the temperature distribution in the susceptor changes according to the proportion of hydrogen gas contained in the cooling gas, it is applied to each of the first heater and the second heater according to the proportion of hydrogen gas contained in the cooling gas. By changing the power to be generated, a semiconductor having a uniform emission wavelength or composition distribution within the substrate plane can be grown on the substrate.

  In the semiconductor manufacturing method according to the present invention, when increasing the ratio of hydrogen gas contained in the cooling gas, the power applied to the second heater may be reduced compared to the power applied to the first heater. The reason why it is preferable is that the temperature of the susceptor decreases toward the outer periphery when the proportion of hydrogen gas contained in the cooling gas increases.

  In the semiconductor manufacturing method according to the present invention, when the ratio of nitrogen gas contained in the cooling gas is increased, the power applied to the second heater may be increased as compared with the power applied to the first heater. The reason why it is preferable is that the temperature of the susceptor increases toward the outer periphery as the ratio of nitrogen gas contained in the cooling gas increases.

  In the method for manufacturing a semiconductor according to the present invention, the heater provided for heating the substrate has a structure in which the heater is divided into at least a first heater and a second heater in order from the inside on a concentric circle, It is preferable to grow the semiconductor while changing the power applied to each of the first heater and the second heater in accordance with the proportion of hydrogen gas contained in the source gas.

  In this way, the temperature distribution in the susceptor that changes according to the type of gas used as the process gas or the type of gas used as the cooling gas can be adjusted uniformly. In particular, since the temperature distribution in the susceptor changes according to the proportion of hydrogen gas contained in the source gas, it is applied to each of the first heater and the second heater according to the proportion of hydrogen gas contained in the source gas. By changing the power to be generated, a semiconductor having a uniform emission wavelength or composition distribution within the substrate plane can be grown on the substrate.

  In the semiconductor manufacturing method according to the present invention, when increasing the proportion of hydrogen gas contained in the source gas, the power applied to the second heater can be reduced compared to the power applied to the first heater. The reason why it is preferable is that the temperature of the susceptor decreases toward the outer periphery as the proportion of hydrogen gas contained in the source gas increases.

  In the semiconductor manufacturing method according to the present invention, when the ratio of nitrogen gas contained in the source gas is increased, the power applied to the second heater may be increased compared to the power applied to the first heater. The reason why it is preferable is that the temperature of the susceptor increases toward the outer periphery when the ratio of nitrogen gas contained in the raw material gas increases.

  According to the metal organic chemical vapor deposition apparatus and the semiconductor manufacturing method according to the present invention, it is possible to prevent the reaction product from being deposited on a portion other than the substrate in the chamber, so that a semiconductor can be manufactured with good reproducibility. In particular, the present invention is effective when manufacturing a group III nitride semiconductor.

(First embodiment)
Hereinafter, a metal organic chemical vapor deposition apparatus and a semiconductor layer manufacturing method according to a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing a configuration of a metal organic chemical vapor deposition apparatus (hereinafter referred to as an MOCVD apparatus) according to a first embodiment of the present invention.

  In the MOCVD apparatus shown in FIG. 1, a stainless steel gas introduction pipe 11, a flow channel 12, which will be described later in detail, and an exhaust pipe 4 made of quartz for exhausting gas are arranged in a horizontal direction inside a stainless steel chamber 10. Specifically, the horizontal MOCVD apparatus has the following configuration.

  As shown in FIG. 1, a gas introduction pipe 11 is provided inside the chamber 10 so as to extend from a gas introduction port (described later) installed on the side wall of the chamber 10, and is connected to the gas introduction pipe 11. As shown, a flow channel 12 is provided. An exhaust pipe 13 for exhausting the internal gas to the outside is provided inside the chamber 10 so as to extend from the vicinity of the end of the flow channel 12 to the side wall of the chamber 10. An opening is formed in the lower part of the flow channel 12, and a carbon susceptor 15 fixed by a rotating shaft 14 extending from the outside to the inside of the chamber 10 is provided in the opening. When the semiconductor is grown, the substrate 1A is mounted on the susceptor 15. Note that three 2-inch substrates can be mounted on the susceptor 15.

  The rotating shaft 14 has a hollow structure, and a thermocouple (not shown) for measuring the temperature of the susceptor 15 is provided inside the hollow shaft 14. In the following description, unless otherwise noted, the temperature of the susceptor 15 means the temperature at the position of the thermocouple. In addition, a heater 16 made of a resistance wire for heating the susceptor 15 is provided below the susceptor 15. In addition, an observation window 17 is provided at the upper portion of the chamber 10 so that a semiconductor that grows crystals on the substrate 1A mounted on the susceptor 15 can be observed. A film thickness measuring device 18 is provided above the observation window 17 to measure the film thickness of a semiconductor layer that grows crystals on the substrate 1A. The film thickness measuring device 18 irradiates the substrate 1A with white light 18a and analyzes the reflection spectrum to analyze the film thickness. Since interference occurs in the reflection spectrum in accordance with the film thickness of the semiconductor layer on which the crystal is grown, the film thickness can be measured by analyzing the reflection spectrum. During crystal growth, since the susceptor 15 is rotated by the rotating shaft 14, it is necessary to measure the film thickness in synchronization with the position of the substrate 1A. For this reason, the rotation shaft 14 is provided with a rotation angle detection mechanism 19, and the film thickness measurement device 18 receives a rotation signal from the rotation angle detection mechanism 19 through the rotation signal cable 20 and takes the position of the substrate 1A. The film thickness can be measured synchronously.

  Hereinafter, the configuration of the MOCVD apparatus shown in FIG. 1 will be described more specifically.

  The gas introduction pipe 11 is provided with a group V gas introduction port 2a and a group III gas introduction port 2b which are separated from each other up to the vicinity of the substrate 1A as gas introduction ports for introducing a raw material gas. As a result, it is possible to prevent a gas phase reaction between ammonia, which is a group V gas, and an organic metal, which is a raw material of the group III nitride semiconductor, before reaching the vicinity of the substrate 1A. Further, since the group V gas inlet 2a and the group III gas inlet 2b are provided in this order from the side closer to the susceptor 15, ammonia as the group V gas can be effectively supplied onto the surface of the substrate 1A. it can. Further, the gas introduction pipe 11 is provided with a cooling gas introduction port 2d as a gas introduction port for the purpose of cooling the flow channel 12. Further, the group V gas inlet 2a, the group III gas inlet 2b, and the cooling gas inlet 2d are provided in order from the bottom so as to overlap, and gas can be introduced into the flow channel 12 from the same side in the chamber 10. It has a configuration.

  The flow channel 12 will be described with reference to FIG.

  As shown in FIG. 2, the flow channel 12 is made of quartz, and includes a combination of a flow channel base 12a, a process gas flow channel 12b, and a cooling gas flow channel 12c.

  The flow channel base 12a has a role of supporting the entire flow channel 12, and has an opening into which the susceptor 15 enters near the center.

  The process gas flow channel 12b is superimposed on the flow channel base 12a. Group V gas introduced from the group V gas inlet 2a and flowing through the group V gas flow 3a (see FIG. 1), and group III gas introduced from the group III gas inlet 2b and flowing through the group III gas flow 3b (see FIG. 1) III The group gas flows in a space between the process gas flow channel 12b and the flow channel base 12a, that is, in a region surrounded by the upper wall a1 of the flow channel base 12a and the inner wall b1 of the process gas flow channel 12b.

  The cooling gas flow channel 12c is superimposed on the process gas flow channel 12b. The cooling gas introduced from the cooling gas inlet 2d and flowing through the cooling gas flow 3d (see FIG. 1) is a space between the cooling gas flow channel 12c and the process gas flow channel 12b, that is, above the process gas flow channel 12b. It flows in a region surrounded by the wall b2 and the inner wall c1 of the cooling gas flow channel 12c.

  As described above, the flow channel 12 is configured so that the process gas flow channel 12b and the cooling gas flow channel 12c overlap with each other, so that the flow channel 12 is introduced from the cooling gas inlet 2d (see FIG. 1) flowing in the cooling gas flow channel 12c. The cooled cooling gas flows on the process gas flow channel 12b, that is, on the upper wall b2 of the process gas flow channel 12b, so that the process gas flow channel 12b can be effectively cooled.

  Here, a modified example of the configuration of the flow channel 12 will be described with reference to FIGS. 3 (a) and 3 (b).

  As shown in FIG. 3 (a), the flow channel 12 is made of quartz, and has a configuration in which a flow channel base 12a, a process gas flow channel 12b, and a cooling gas flow channel 12d having a hollow portion inside are stacked. Also good. With such a configuration, only the process gas flow channel 12b having a high replacement frequency can be easily replaced. Even in such a case, the upper wall b2 of the process gas flow channel 12b can be indirectly cooled by the cooling gas flow 3d.

  Further, as shown in FIG. 3B, the flow channel 12 is made of quartz, and a flow channel base 12a, a process gas flow channel 12b, a heat shield 12e having an observation window, and a cooling gas flow channel 12c are overlapped. It may be a configured. The reason for this configuration is that quartz has a large radiant heat, so that the cooling effect on the process gas flow channel 12b can be prevented from being suppressed by providing the heat shield plate 12e.

  In addition, although the flow channel 12 mentioned above demonstrated the case where the flow channel base 12a, the process gas flow channel 12b, and the cooling gas flow channel 12c consisted of only the lamination | stacking, these members were welded etc. as needed. May be integrated. The material constituting the flow channel 12 is a material other than quartz, which can withstand high temperatures and is not corroded by ammonia, for example, a material made of alumina, sapphire, or SiC, or any of these materials It is also possible to use a material coated with, for example.

  Further, the case where the members such as the process gas flow channel 12 are made of integral quartz has been described, but the process gas flow channel 12 may be a case where quartz is doubled. Even in this case, the upper wall 12b of the process gas flow channel 12b can be directly cooled by the cooling gas flow 3d.

  The exhaust pipe 13 exhausts the source gas flowing in the process gas flow channel 12 and the cooling gas flowing in the cooling gas flow channel 12c, and is an exhaust gas processing apparatus (not shown) arranged outside the MOCVD apparatus. 2) through the exhaust port 4a.

  Further, as shown in FIG. 1, the flow channel 12 and the exhaust pipe 13 are arranged, so that the group V gas flow 3a through which the group V gas flows and the group III gas flow 3b through which the group III gas flows, and the cooling gas are provided. The cooling gas flow 3d through which the gas flows is separated immediately above the substrate 1A mounted on the susceptor 15 and merges immediately before the exhaust pipe 13. For this reason, the group V gas flow 3a and the group III gas flow 3b immediately above the substrate 1A are not affected by the cooling gas flow 3d.

  As shown in FIG. 1, the cooling gas inlet 2d is formed integrally with the group V gas inlet 2a and the group III gas inlet 2b in the gas inlet pipe 11. For this reason, the process gas flow channel 12 can be more effectively cooled without separately providing the cooling gas inlet 2d at a position where the process gas flow channel 12 is cooled by the introduced cooling gas. As shown in FIGS. 1 and 2, the structure in which the process gas is guided onto the outer wall b2 of the process gas flow channel 12b is a simple structure in which the cooling gas flow channel 12c is simply overlaid on the process gas flow channel 12b. is there. Therefore, the MOCVD apparatus shown in FIG. 1 can easily realize the effect obtained by the cooling gas flow 3d without depending on the assembly accuracy of the flow channel 12. Here, the case where the cooling gas inlet 2d is formed integrally with the group V gas inlet 2a and the group III gas inlet 2b has been described. However, for example, in the chamber 10 such as the upper wall of the chamber 10 or the like. Even when the cooling gas inlet 2d is provided at another position, the effect of cooling the process gas flow channel 12b is realized by blowing the cooling gas from the position to the outer wall b2 of the process gas flow channel 12b. Is done.

  Next, with respect to the measurement result of the reflection spectrum analyzed by the film thickness measuring device 18 when the group III nitride semiconductor is continuously grown using the MOCVD apparatus according to the first embodiment of the present invention, A description will be given including the case where there is no gas flow 3d.

  First, FIG. 4 is a schematic cross-sectional view showing a semiconductor structure in which a group III nitride semiconductor is continuously grown using the MOCVD apparatus according to the first embodiment of the present invention. On the resulting substrate 1A, a low-temperature GaN buffer layer 31 and a GaN layer 32 are grown in order from the bottom.

  Hereinafter, each step of growing a semiconductor having the structure shown in FIG. 4 will be described. Here, first, for comparison with the case where a cooling gas is not flowed, which will be described later, in the MOCVD apparatus shown in FIG. 1, a single growth method of a semiconductor without flowing a cooling gas will be described.

  First, after the substrate 1A made of sapphire is placed on the susceptor 15, the inside of the chamber 10 is sealed.

  Next, the heater 16 is heated so that the temperature of the susceptor 15 becomes 1000 ° C. while introducing hydrogen gas from the group V gas inlet 2a and the group III gas inlet 2b at a flow rate of 30 L / min. . By a process called thermal cleaning, impurities adhering to the surface of the substrate 1A made of sapphire are evaporated.

  Next, the temperature of the susceptor 15 is set to 500 ° C. When the temperature of the susceptor 15 is stabilized, ammonia is introduced from the V group gas inlet 2a by switching the flow rate of 20 L / min to ammonia among the hydrogen gas introduced into the V group gas inlet 2a. Ammonia is supplied into the process gas flow channel 12b. Subsequently, when the flow of gas introduced from the group V gas inlet 2a is stabilized, trimethylgallium (TMG) is transported to the hydrogen gas introduced into the group III gas inlet 2b, and TMG is supplied to the process gas flow channel. 12b is supplied. Since the flow rate of the organic metal is on the order of μmol per minute and is very small, the ratio to the total flow is very small. By passing hydrogen gas through the container in which the organic metal is stored, It is transported by hydrogen gas and introduced into the process gas flow channel 12b. Thereby, ammonia and TMG react on the heated substrate 1A, and the low-temperature GaN buffer layer 31 grows.

  Next, when the low-temperature GaN buffer layer 31 is grown to 20 nm, the supply of TMG introduced into the group III gas inlet 2b is stopped, and the flow rate of the group V gas flow 3a and the flow rate of the group III gas flow 3b are kept as they are. The temperature of the susceptor 15 is raised to 1000 ° C. by supplying only ammonia and hydrogen gas.

  Next, when the temperature of the susceptor 15 is stabilized at 1000 ° C., the flow rate of the group V gas flow 3a and the flow rate of the group III gas flow 3b are maintained as they are, and TMG is introduced again into the group III gas inlet 2b, The GaN layer 32 is grown by 2 μm.

  Next, when the GaN layer 32 grows by 2 μm, the supply of TMG introduced into the group III gas inlet 2b is stopped and the heater 16 is turned off to lower the temperature of the susceptor 15. When the temperature of the susceptor 15 reaches 500 ° C., the ammonia introduced into the group V gas inlet 2a is switched to hydrogen gas, and the supply of ammonia is also stopped. Further, after the temperature of the susceptor 15 is lowered to near room temperature, the substrate 1A is taken out.

  The series of steps described above is a single growth.

  Here, for comparison, each of the case where there is no cooling gas flow 3d and the case where there is the cooling gas flow 3d through steps other than the step of mounting the substrate 1A on the susceptor 15 and the step of removing the substrate 1A from the susceptor 15 In this case, the change for each growth of the intensity of a specific wavelength of the reflection spectrum measured by the film thickness measuring device 18 was measured. Since the reflection spectrum has a property depending on the film thickness as described above, in any case, the reflection spectrum intensity immediately after the GaN layer 32 is grown by 2 μm is measured and the measurement wavelength is made constant at 600 nm. Thus, each change was measured under the condition where there is no influence of the film thickness or the measurement wavelength. Further, nitrogen gas was used as the cooling gas introduced from the cooling gas inlet 2d, and the flow rate thereof was set to 20 L / min.

  When the above-described single growth is repeated under the above conditions, the reaction product is usually deposited on the inner wall b1 in contact with the source gas in the process gas flow channel 12b. For this reason, when the white light 18a emitted from the film thickness measuring device 18 is blocked by the reaction deposit, the reflection spectrum intensity from the substrate 1A decreases. Since the noise increases when the reflection spectrum intensity is attenuated to 20% of the reflection spectrum intensity obtained when the unused process gas flow channel 12b is used (when the MOCVD apparatus according to this embodiment is used), the noise increases. The film thickness measuring device 18 in the embodiment cannot accurately measure the reflection spectrum intensity. For this reason, when the reflection spectrum intensity is attenuated to about 20%, maintenance for replacing the flow channel 12 occurs.

  FIG. 5 shows the growth frequency dependence of the reflection spectrum intensity. Specifically, when there is a cooling gas flow 3d of nitrogen introduced from the cooling gas inlet 2d and when the cooling gas flows from the cooling gas inlet 2d, FIG. The relationship between the reflection spectrum intensity (relative value) and the number of times of growth (times) is shown for each case where no is introduced.

  As shown in FIG. 5, when the cooling gas is not flowed, the reflection spectrum intensity is almost zero when the above-mentioned one growth is performed five times, and the reflection spectrum cannot be measured. Become. On the other hand, when the cooling gas is introduced and the cooling gas flow 3d is present, the deposition of the reaction product is suppressed as compared with the case where the cooling gas is not supplied, and the above-described one growth is performed approximately 20 times. Until then, it was possible to measure the reflection spectrum. Such a result was obtained because the process gas flow channel 12b was cooled by the cooling gas flow 3d, thereby suppressing the deposition of reaction products.

  Here, the cooling temperature by the cooling gas flow 3d can be considered as follows. In the case of growing GaN with TMG and ammonia, it has been found that the growth starts at about 350 ° C. and reaches 500 ° C. or higher and saturates at a growth rate almost controlled by the supply amount. Therefore, by reducing the temperature of the process gas flow channel 12b to less than 350 ° C. by the cooling gas flow 3d, it is possible to suppress the deposition of reaction products.

  The MOCVD apparatus having the cooling gas flow 3d according to the present embodiment has the following advantages. As is apparent from the results shown in FIG. 5, in the case of an MOCVD apparatus that does not have the cooling gas flow 3d, maintenance is performed to replace the flow channel 12 every time the growth is performed several times in order to measure the reflection spectrum. On the other hand, according to the MOCVD apparatus having the cooling gas flow 3d according to the present embodiment, the maintenance cycle can be greatly extended. Further, since the reaction product can be prevented from being deposited on the process gas flow channel 12b by the cooling gas flow 3d, it is possible to reduce the reaction product from flying onto the substrate 1A. It becomes possible to grow.

  In addition, the MOCVD apparatus according to the present embodiment has the following advantages compared to MOCVD apparatuses having other mechanisms. In general, when a group III nitride semiconductor is grown using an MOCVD apparatus, a highly reactive ammonia gas is used, so that the degree of freedom in selecting a material is limited. For example, when a water cooling mechanism or a heat dissipation mechanism made of stainless steel, copper, aluminum or the like is used as a means for cooling the flow channel, a problem such as corrosion of these mechanisms due to reaction with ammonia gas occurs. Alternatively, it is very difficult to select a material constituting the heat dissipation mechanism and it is very difficult to manufacture a structure including these mechanisms. Even when a structure using these mechanisms can be realized, problems such as a short maintenance cycle are likely to occur. For example, as an apparatus for growing GaAs, an apparatus having a water cooling mechanism made of stainless steel, copper, aluminum or the like can be realized. Therefore, there is no need to worry about the problem of corrosion of the water cooling mechanism. However, when growing a group III nitride semiconductor, it is difficult to provide a water cooling mechanism made of stainless steel, copper, aluminum, or the like that is highly reactive with ammonia gas.

  On the other hand, in the MOCVD apparatus according to the present embodiment, the cooling gas flow channel 12c made of quartz, which is the same material as the process gas flow channel 12b, is overlaid on the process gas flow channel 12b, thereby providing a cooling gas flow channel. The cooling effect on the process gas flow channel 12b can be realized by a simple configuration in which the cooling gas is caused to flow inside the 12c. Thus, in this embodiment, since the process gas flow channel 12b is cooled using the cooling gas, the cooling effect is considered to be small compared to a cooling method such as water cooling. As described above, when the temperature is lower than 350 ° C., the effect of suppressing the deposition of the reaction product appears. For this reason, even if it does not cool strongly to 100 degrees C or less by water cooling, the required cooling effect can be acquired with the cooling system by the cooling gas flow 3d using the cooling gas in this embodiment.

  In this embodiment, as described above, the V group gas introduction port 2a, the III group gas introduction port 2b, and the cooling gas introduction port 2d are provided independently from each other, and are introduced from the V group gas introduction port 2a. Since the group V gas, the group III gas introduced from the group III gas introduction port 2b, and the cooling gas introduced from the cooling gas introduction port 2d are introduced into independent spaces, the respective gases are independently supplied. Can be controlled. This is effective in the following cases. For example, when the flow rate of the process gas flow (3a, 3b) is decreased due to a request for crystal growth, the temperature of the flow channel 12 may increase due to a decrease in the amount of heat transported by the process gas. At this time, the temperature of the flow channel 12 can be kept low by increasing the flow rate of the cooling gas flow 3d. Thereby, the freedom degree of the setting of process gas flow (3a, 3b) can be raised.

  On the other hand, in the configuration in which the flow of the cooling gas is mixed with the flow of the raw material gas as in the case of the conventional MOCVD apparatus, when the flow rate of the raw material gas needs to be reduced, the flow of the cooling gas is reduced for the reason described above. Although it is necessary to increase the cooling effect, as a result, the flow rate on the substrate does not change much as a result. Therefore, there is a problem that it is not possible to sufficiently respond to a request for crystal growth such as reducing the flow rate of the source gas. However, according to the MOCVD apparatus according to this embodiment, as described above, since the degree of freedom in setting the source gas is high, it is possible to sufficiently respond to a request for crystal growth.

  As described above, according to the MOCVD apparatus according to the first embodiment of the present invention, the process gas flow channel 12b is cooled by cooling the process gas flow channel 12b with the cooling gas flow 3d in the cooling gas flow channel 12c. It is possible to prevent the reaction product from being deposited on a member such as quartz constituting the structure. Therefore, the maintenance cycle for the MOCVD apparatus can be extended, and the reaction product can be prevented from flying onto the substrate 1A, and a nitride semiconductor can be grown stably and with good reproducibility.

(Second Embodiment)
Hereinafter, a semiconductor manufacturing method according to the second embodiment of the present invention will be described.

  Specifically, a semiconductor manufacturing method according to the second embodiment of the present invention uses the same apparatus as the MOCVD apparatus shown in FIGS. 1 and 2 according to the first embodiment of the present invention. Although this is a method of continuously growing a semiconductor having the same structure as the semiconductor shown in FIG. 4 in the first embodiment of the invention, the description of the parts common to the first embodiment will not be repeated.

  The semiconductor manufacturing method according to the second embodiment of the present invention is different from the semiconductor manufacturing method according to the first embodiment of the present invention in that the cooling gas constituting the cooling gas flow 3d is the first embodiment. The hydrogen gas is used in place of the nitrogen gas used in the embodiment, and here, the semiconductor shown in FIG. 4 was manufactured with a hydrogen gas flow rate of 20 L / min.

  FIG. 6 shows the dependence of the reflection spectrum intensity on the number of growth times. Specifically, in the case of the cooling gas flow 3d made of hydrogen gas in the present embodiment and the cooling gas flow made of nitrogen gas in the first embodiment. In each of the cases of 3d, the relationship between the reflection spectrum intensity (relative value) and the number of times of growth (times) is shown.

  As shown in FIG. 6, when the cooling gas flow 3d is made of hydrogen gas, the reflection spectrum can be measured until the above-described single growth described with reference to FIG. 4 is performed approximately 30 times. It was. Therefore, according to the present embodiment in which the cooling gas flow 3d is made of hydrogen gas, the reflection spectrum can be measured up to 20 times of growth in the case where the cooling gas flow 3d is made of nitrogen gas. Compared with the form, the number of times of growth at which reflection spectrum can be measured can be increased.

  The reason why such an effect is obtained is that hydrogen gas has a cooling effect higher than that of nitrogen gas, and therefore, deposition of reaction products on the process gas flow channel 12b can be further suppressed. It is done.

  Next, another example of the semiconductor manufacturing method according to the second embodiment of the present invention will be described.

  Specifically, another example of the semiconductor manufacturing method according to the second embodiment of the present invention is the same apparatus as the MOCVD apparatus according to the first embodiment of the present invention shown in FIGS. And a method of manufacturing a semiconductor having the structure shown in FIG.

  FIG. 7 shows a semiconductor structure, that is, an LED structure manufactured by another example of the semiconductor manufacturing method according to the second embodiment of the present invention. That is, as shown in FIG. 7, the low-temperature GaN buffer layer 31 and the GaN layer 32 are grown in order from the bottom on the substrate 1A made of sapphire, and subsequently the n-type GaN contact layer 33 and the InGaN active layer 34. And the p-type GaN contact layer 35 is grown in order from the bottom.

  Below, each process of growing the semiconductor which consists of LED structure shown in FIG. 7 is demonstrated. 7 is the same as the structure shown in FIG. 4 in the structure shown in FIG. 4, and the following description will focus on the differences.

  First, after performing thermal cleaning in the same manner as in the first embodiment while introducing hydrogen gas constituting the cooling gas flow 3d from the cooling gas inlet 2d at a flow rate of 20 L / min, at 500 ° C. The low-temperature GaN buffer layer 31 is grown by 20 nm, and the GaN layer 32 is grown by 2 μm at 1000 ° C.

  Subsequently, the hydrogen gas at a flow rate of 20 L / min is maintained as it is as the cooling gas flow 3d, and the n-type GaN contact layer 33 is grown by 2 μm at 1000 ° C. Here, Si, Ge, or the like can be used as the n-type dopant. In this case, doping can be performed by introducing a predetermined amount of a doping gas such as monosilane or monogermane into the process gas flow channel 12b. Further, the doping gas may be introduced from any one of the group V gas inlet 2a and the group III gas inlet 2b. Further, since Si or Ge enters the group III site of GaN, it is preferable to mix a doping gas such as monosilane or monogermane into the group III gas flow 3b because the in-plane uniformity on the surface of the substrate 1A is improved.

  Next, while stopping the supply of TMG introduced into the group III gas inlet 2b and continuing the supply of ammonia introduced into the group V gas inlet 2a, the temperature of the susceptor 15 is set to a temperature preferable for the growth of InGaN. The temperature is lowered to 750 ° C. When the temperature is stabilized, all hydrogen gas introduced into the gas introduction pipe 11 is switched to nitrogen gas. That is, a mixed gas composed of nitrogen gas at a flow rate of 10 L / min and ammonia at a flow rate of 20 L / min are supplied to the group V gas flow 3a, and nitrogen gas at a flow rate of 30L / min is supplied to the group III gas flow 3b. In the cooling gas flow 3d, 20 L of nitrogen gas is supplied per minute.

  In this state, after maintaining the time until the hydrogen gas existing in the chamber 10 is almost expelled, TMG and trimethylindium (TMI) are mixed and introduced into the group III gas flow 3b, whereby the InGaN activity is increased. Layer 34 is grown. In general, when InGaN is grown, TMI is supplied in a considerably excessive amount because the In incorporation efficiency during the growth is low. For this reason, even when the grown InGaN layer is thin, deposition of reaction products on the process gas flow channel 12b becomes relatively large. However, in this step, the InGaN active layer 34 that sufficiently incorporates In while suppressing deposition of reaction products by using nitrogen gas instead of hydrogen gas as the gas constituting the cooling gas flow 3d. Can be realized. This mechanism will be described in detail later.

Subsequently, when the InGaN active layer 34 is grown to 5 nm, all the nitrogen gas introduced into the gas introduction tube 11 is switched again to hydrogen gas, and the temperature of the susceptor 15 is raised to 1000 ° C. That is, a mixed gas composed of hydrogen gas at a flow rate of 10 L / min and ammonia at a flow rate of 20 L / min are supplied to the group V gas flow 2a, and hydrogen gas at a flow rate of 30L / min is supplied to the group III gas flow 2b. In the cooling gas flow 3d, hydrogen gas is supplied at a flow rate of 20 L / min. When the temperature and flow are stabilized, the p-type GaN contact layer 35 is grown by 0.2 μm. Mg or the like can be used as the p-type dopant. In this case, doping can be performed by introducing a doping gas such as cyclopentadienyl magnesium (Cp ₂ Mg) into the process gas flow channel 12b. Further, since Mg enters the group III site of GaN, in-plane uniformity on the surface of the substrate 1A is improved by mixing a doping gas such as cyclopentadienyl magnesium (Cp ₂ Mg) into the group III gas flow 3b. Therefore, it is preferable.

  Through the above series of steps, a blue LED wafer having a wavelength of 460 nm having the InGaN active layer 34 in which In is sufficiently taken in can be manufactured.

  FIG. 8 shows a method using the nitrogen gas described in the present embodiment as the cooling gas constituting the cooling gas flow 3d when the InGaN active layer 34 is grown, and hydrogen gas at a flow rate of 20 L / min instead of the nitrogen gas. The figure which compared the photoluminescence (PL) spectrum in each with the method of using is shown. PL is a technique for examining a light emission wavelength by applying a laser beam to a wafer, and a technique for examining a light emission wavelength of an LED in a wafer state.

  Since hydrogen gas has a low molecular weight, it has the property of diffusing even from a slight gap. Even if the cooling gas flow 3d, the group III gas flow 3b, and the group V gas flow 3a are separated as in the flow channel 12 constituting the MOCVD apparatus according to the present embodiment, the gas introduction pipe 11 and the flow Hydrogen diffuses and reaches the surface of the substrate 1A through a gap where the channel 12 is connected or a gap between quartz members constituting the flow channel 12 or the like. For this reason, when hydrogen gas is used as the cooling gas used when growing the InGaN active layer 34, a very small amount of hydrogen gas reaches the surface of the InGaN active layer 34 through the gaps described above, so that InGaN is decomposed by hydrogen. As a result, the In composition ratio in the InGaN active layer 34 is reduced, and as shown in FIG. 8, the wavelength is shortened, and the crystallinity of the InGaN active layer 34 is reduced to reduce the emission intensity. By analogy with the amount of change in wavelength and the like, the concentration of diffused hydrogen on the substrate 1A is 1% or less. On the other hand, in the present embodiment, since the nitrogen gas is used as the gas constituting the cooling gas flow 3d without using the hydrogen gas, there is no diffusion of the hydrogen gas as described above. In is sufficiently incorporated into In, and excellent values of both PL intensity and wavelength are obtained.

  FIG. 9 shows the growth frequency dependence of the reflection spectrum intensity. Specifically, the nitrogen gas described in the present embodiment is used as the cooling gas constituting the cooling gas flow 3d when the InGaN active layer 34 is grown. Between the reflection spectrum intensity (relative value) and the number of times of growth (times) when LED growth is repeated in each of the method using hydrogen and the method using hydrogen gas at a flow rate of 20 L / min instead of nitrogen gas Is shown. As is apparent from FIG. 9, there is little difference in the dependence of the reflection spectrum intensity on the number of times of growth depending on whether the cooling gas used for growing the InGaN active layer 34 is made of nitrogen gas or hydrogen gas. Absent. That is, regardless of which gas is used, the reflection spectrum can be measured until the LED is grown 20 times. When growing the InGaN active layer 34, if nitrogen gas is used as the cooling gas, the cooling effect is lower than that when hydrogen gas is used as described above, but the growth temperature of the InGaN active layer 34 is 750 ° C. Since the temperature is lower than the growth temperature of GaN or the like, a sufficient effect can be obtained even when nitrogen gas is used as a cooling gas when the InGaN active layer 34 is grown.

  The number of reflection spectra that can be measured is 20 as shown in FIG. 9, which is lower than that shown in FIG. 6. In the case shown in FIG. The measurement target is a semiconductor grown up to the layer 32, and in the case shown in FIG. 9, the measurement target is a semiconductor made of a thick LED in which a further film is deposited on the GaN layer 32. Needless to say.

  In this embodiment, nitrogen gas is used as a cooling gas during the growth of the InGaN active layer 34, but a gas other than nitrogen gas does not contain hydrogen gas and adversely affects the growth of the InGaN active layer 34. Any gas may be used as long as the gas does not give any oxygen. For example, a rare gas such as helium, argon, xenon, or krypton can be used instead of nitrogen gas. A gas composed of hydrocarbon such as methane, ethylene, acetylene, or butane can also be used. However, when a hydrocarbon gas is used as the nitrogen gas, the carbon number may be about 6 or less. This is because when the number of carbons exceeds about 6, not only a sufficient vapor pressure as a gas cannot be obtained, but also hydrocarbons are decomposed by the heat for heating the substrate 1A to generate hydrogen, which is not preferable. It is. Ammonia can also be used as the cooling gas. This is because ammonia is a raw material gas, so that no adverse effect occurs even if ammonia is introduced into the chamber 10. In addition, a gas obtained by mixing the above-described usable gas can be used as the cooling gas.

  The above-mentioned gases that do not adversely affect the growth of the InGaN active layer 34 have no adverse effects when used in growing other Group III nitride semiconductors such as GaN, AlN, AlGaN, or InN. Needless to say, the gas described above can be used as the cooling gas in forming the layer.

  As discussed with reference to FIG. 8, the flow channel 12 is assembled so that gas leakage can be completely prevented between the cooling gas flow 3d, the group III gas flow 3b, and the group V gas flow 3a. It is almost impossible. Therefore, in actuality, there is a mutual gas diffusion between the cooling gas flow 3d, the group III gas flow 3b, and the group V gas flow 3a at a concentration of 1% or less, more practically 100 ppm or less. Arise. When a group III nitride semiconductor layer not containing In, such as GaN, AlGaN, or AlN, is grown, the type of cooling gas is hydrogen gas even if the cooling gas is mixed at a concentration of 1% or less. Regardless of whether or not it has little influence on the growth on the substrate 1A. For this reason, when realizing a structure in which the cooling gas flow channel 12c for flowing the cooling gas is separated from the process gas flow channel 12b as much as possible, the concentration of the cooling gas diffused on the substrate 1A is 1% or less. It is preferable to make such a structure.

(Third embodiment)
The MOCVD apparatus and semiconductor manufacturing method according to the third embodiment of the present invention will be described below with reference to the drawings.

  FIG. 10 is a schematic cross-sectional view showing the configuration of the MOCVD apparatus according to the third embodiment of the present invention. In FIG. 10, among the parts constituting the MOCVD apparatus according to the third embodiment of the present invention, it corresponds to the part constituting the MOCVD apparatus according to the first embodiment of the present invention shown in FIG. The same reference numerals are assigned to the parts to be described, and the description thereof will not be repeated. Therefore, hereinafter, the MOCVD apparatus according to the third embodiment of the present invention will be described focusing on the differences from the MOCVD apparatus according to the first embodiment of the present invention.

  The MOCVD apparatus according to the third embodiment of the present invention shown in FIG. 10 is different from the MOCVD apparatus according to the third embodiment of the present invention shown in FIG. is there. That is, the gas introduction pipe 11 shown in FIG. 10 is provided between the group III gas introduction port 2b and the cooling gas introduction port 2d in addition to the group V gas introduction port 2a, the group III gas introduction port 2b, and the cooling gas introduction port 2d. Is provided with a pressure gas inlet 2c. As described above, the group V gas inlet 2a, the group III gas inlet 2b, and the pressure gas inlet 2c are installed in this order from the side closer to the susceptor 15, so that ammonia is effectively supplied onto the substrate 1A. be able to. In order to facilitate compatibility with the MOCVD apparatus shown in FIG. 1, that is, in order to allow the flow channel 12 shown in FIGS. 1 and 2 to be used as it is, the gas introduction pipe 11 shown in FIG. The overall height of the gas introduction pipe 11 and the height of the cooling gas introduction port 2d are the same, and the heights of the V group gas introduction port 2a, the III group gas introduction port 2b, and the pressing gas introduction port 2c are reduced. It has the composition to do.

  According to the MOCVD apparatus according to the third embodiment of the present invention shown in FIG. 10, the group III gas flow 3b and the group V gas flow 3a are generated by the pressing gas flow 3c made of the pressing gas introduced from the pressing gas inlet 2c. Since the gas flows in the vicinity of the substrate 1A in the process gas flow channel 12b, the concentration of the source gas on the substrate 1A can be effectively increased as compared with the case where there is no pressing gas flow 3c. For this reason, the utilization efficiency of source gas can be increased.

  Hereinafter, a semiconductor manufacturing method using the MOCVD apparatus shown in FIG. 10 according to the third embodiment of the present invention will be described. A semiconductor using the MOCVD apparatus shown in FIG. 1 according to the first embodiment of the present invention will be described. This will be described in comparison with the manufacturing method. In any of the manufacturing methods, the case where the semiconductor having the LED structure shown in FIG. 7 is continuously grown will be described. The growth of the semiconductor having the LED structure using the MOCVD apparatus shown in FIG. The method is as described in the second embodiment of the present invention.

  Therefore, a semiconductor manufacturing method using the MOCVD apparatus shown in FIG. 10 according to the third embodiment of the present invention will be described below.

  First, after the substrate 1A is placed on the susceptor 15, a thermal cleaning process is performed. In order to reproduce substantially the same conditions as in the first embodiment of the present invention, the total flow rate is set to 60 L / min. Specifically, nitrogen gas is supplied from the pressure gas inlet 2c at a flow rate of 20 L / min, hydrogen gas is supplied from the group V gas inlet 2a at a flow rate of 20 L / min, and hydrogen gas is supplied from the group III gas inlet 2b at a rate of 20 L / min. The temperature of the susceptor 15 is set to 1000 ° C. while introducing hydrogen gas into the gas introduction pipe 11 at a flow rate of 20 L / min from the cooling gas inlet 2d.

  Next, the flow rate of each gas introduced into each inlet 2a-2d is maintained as it is, the temperature of the susceptor 15 is set to 500 ° C., and the low-temperature GaN buffer layer 31 is grown on the substrate 1A. When the temperature of the susceptor 15 is stabilized, ammonia is introduced by switching the flow rate of 15 L / min to ammonia in the hydrogen gas introduced from the group III gas inlet 2b. Further, when the gas flow is stabilized, trimethylgallium (TMG) is transported to the hydrogen gas introduced from the group V gas inlet 2a to introduce TMG into the group III gas flow 3b. As described above, since the gas use efficiency is increased by the pressure gas flow 3c, according to the present embodiment using the MOCVD apparatus shown in FIG. 10, the flow rate of ammonia when using the MOCVD apparatus shown in FIG. Even with an ammonia flow rate (15 L / min) less than 20 L / min, a film having substantially the same characteristics can be grown.

  Next, when the low-temperature GaN buffer layer 31 is grown to 20 nm, the supply of TMG introduced into the group V gas inlet 2a is stopped, and ammonia and hydrogen gas are kept in the state where the flow rates of the gas flows 3a to 3d are kept as they are. Only, and the temperature of the susceptor 15 is raised to 1000 ° C. When the temperature of the susceptor 15 is stabilized at 1000 ° C., TMG is again introduced into the group V gas inlet 2a to grow the GaN layer 32 by 2 μm.

  Subsequently, the flow rates of the gas flows 3a to 3d are maintained as they are, and as described in the second embodiment, a doping gas such as monosilane gas is introduced into the process gas flow channel 12b, so that the n-type at 1000 ° C. A GaN contact layer 33 is grown by 2 μm.

  Next, the temperature of the susceptor 15 is lowered to 750 ° C. while the supply of TMG introduced into the group V gas inlet 2a is stopped and ammonia is still supplied. When the temperature of the susceptor 15 is stabilized, all hydrogen gas introduced into the gas introduction pipe 11 is switched to nitrogen gas. That is, a mixed gas composed of nitrogen gas at a flow rate of 5 L / min and ammonia at a flow rate of 15 L / min is supplied to the group V gas flow 3a. A nitrogen gas having a flow rate of 20 L / min is supplied to the group III gas flow 3b. Nitrogen gas at a flow rate of 20 L / min is passed through the pressing gas flow 3c. The cooling gas flow 3d is supplied with 20 L of nitrogen gas per minute. After maintaining this state for a predetermined time, the InGaN active layer 34 is grown by introducing TMG and trimethylindium (TMI) mixed with the group III gas flow 3b.

  Next, when the InGaN active layer 34 is grown to 5 nm, all the nitrogen gas introduced into the gas introduction tube 11 is switched again to hydrogen gas, and the temperature of the susceptor 15 is raised to 1000 ° C. That is, a mixed gas composed of hydrogen gas at a flow rate of 5 L / min and ammonia at a flow rate of 15 L / min is supplied to the group V gas flow 3a. Hydrogen gas at a flow rate of 20 L / min is passed through the group III gas flow 3b. Hydrogen gas at a flow rate of 20 L / min is passed through the pressing gas flow 3c. Hydrogen gas at a flow rate of 20 L / min is passed through the cooling gas flow 3d.

Next, when the temperature of the susceptor 15 and the gas flow are stabilized, TMG and a doping gas such as cyclopentadienylmagnesium (Cp ₂ Mg) are introduced into the process gas flow channel 12b to form a p-type GaN contact. Layer 35 is grown to 0.2 μm.

  Next, when the growth of the p-type GaN contact layer 35 is finished, the supply of the organic metal is stopped, the heater 16 is turned off, and the temperature of the susceptor 15 is lowered. When the temperature of the susceptor 15 reaches 500 ° C., the ammonia introduced into the group V gas flow 3a is switched to hydrogen gas, and the supply of ammonia is also stopped. Further, after the temperature of the susceptor 15 is lowered to near room temperature, the substrate 1A is taken out.

  The series of steps described above is a single growth, and this single growth is repeated.

  FIG. 11 shows the growth frequency dependence of the reflection spectrum intensity. Specifically, the measurement result by the semiconductor manufacturing method according to the second embodiment of the present invention and the third embodiment of the present invention are shown. The comparison with the measurement result by the manufacturing method of the semiconductor which concerns is shown.

  In the method of manufacturing a semiconductor having an LED structure using the MOCVD apparatus shown in FIG. 1 according to the second embodiment of the present invention, the reflection spectrum is measured until approximately 20 times of growth due to the effect of the cooling gas flow 3d. It was possible. In contrast, in the method of manufacturing a semiconductor having an LED structure using the MOCVD apparatus shown in FIG. 10 according to the third embodiment of the present invention, the effect of the pressure gas flow 3c in addition to the effect of the cooling gas flow 3d. Thus, the reflection spectrum can be measured up to about 40 times of growth, so that the maintenance cycle can be further extended as compared with the case of using the MOCVD apparatus shown in FIG. 1 in the first embodiment of the present invention. it can.

  As described above, according to the MOCVD apparatus according to the third embodiment of the present invention, the pressure gas introduction port 2c is provided, and the pressure gas flow 3c flows over the group V gas flow 3a and the group III gas flow 3b. Thus, the maintenance cycle can be further extended. Thereby, since the cost which a maintenance requires can be reduced more, the operation rate of an installation can be improved further. Furthermore, the utilization efficiency of source gases such as ammonia and TMG can be increased.

  The pressure gas introduced into the pressure gas inlet 2c may be any gas as long as it does not adversely affect the growth of the group III nitride semiconductor, for example, helium, argon, xenon instead of nitrogen gas. Alternatively, a rare gas such as krypton can be used. In addition, hydrocarbon gas such as methane, ethylene, acetylene, or butane can be used. However, when hydrocarbon gas is used, the carbon number is preferably about 6 or less. This is because if the number of carbon atoms exceeds about 6, it is not preferable because a sufficient vapor pressure as a gas cannot be obtained. Further, when AlGaN or GaN is grown, hydrogen gas can be used as the pressing gas. However, when InGaN is grown, it is not preferable to use hydrogen gas as the pressing gas in the second embodiment. The reason is the same as described in the form. Moreover, although the mixed gas of the gas mentioned above can also be used as a press gas, when growing InGaN, it is the same point that it is not preferable to use the gas mixed with hydrogen gas.

(Fourth embodiment)
Hereinafter, an MOCVD apparatus and a semiconductor manufacturing method according to a fourth embodiment of the present invention will be described with reference to the drawings.

  FIG. 12 is a schematic cross-sectional view showing a configuration of an MOCVD apparatus according to the fourth embodiment of the present invention. In FIG. 12, among the parts constituting the MOCVD apparatus according to the fourth embodiment of the present invention, it corresponds to the part constituting the MOCVD apparatus according to the third embodiment of the present invention shown in FIG. The same reference numerals are assigned to the parts to be described, and the description thereof will not be repeated. Therefore, hereinafter, the MOCVD apparatus according to the fourth embodiment of the present invention will be described focusing on the differences from the MOCVD apparatus according to the third embodiment of the present invention.

  The MOCVD apparatus according to the fourth embodiment of the present invention shown in FIG. 12 is different from the MOCVD apparatus according to the third embodiment of the present invention shown in FIG. It is a configuration. In addition, since the configuration of the heater 16 is characterized in the present embodiment, a temperature distribution measuring device 21 is provided instead of the film thickness measuring device 18 shown in FIG. 10 for the purpose of confirming the effect of the present embodiment. The temperature distribution measuring device 21 is a device that can analyze infrared rays emitted from the susceptor 15 and display the temperature distribution as an image.

  The heater 16 constituting the MOCVD apparatus shown in FIG. 12 has a configuration in which it is divided into concentric inner and outer heaters 16a and 16b, and the inner and outer heaters 16a and 16b are respectively turned on independently. It is possible to manipulate the current.

  First, in the following, a description will be given of the results of an experiment on how the temperature distribution of the susceptor 15 changes depending on the type of gas used for the cooling gas.

  FIG. 13 shows the temperature distribution of the susceptor 15 when the mixture ratio of nitrogen gas and hydrogen gas is changed in the case of flowing a mixed gas of nitrogen gas and hydrogen gas as the cooling gas flow 3d.

  Here, since the susceptor 15 rotates during heating, it exhibits a concentric temperature distribution. For this reason, the temperature distribution is plotted toward the outer side of a certain radial position with the central portion of the susceptor 15 being 0 mm. At this time, nitrogen gas is flowed through the pressure gas flow 3c at a flow rate of 20 L / min, hydrogen gas is flowed through the group III gas flow 3b at a flow rate of 20 L / min, and the group V gas flow 3a is flowed at 5 L / min. The hydrogen gas at a flow rate and the ammonia at a flow rate of 15 L / min are set to flow, and the set temperature of the susceptor 15, that is, the temperature at the position where the thermocouple is located is set to 1000 ° C. The current of the inner heater 16a and the current of the outer heater 16b are the same. That is, when the outer peripheral current / inner peripheral current is defined as the inner / outer peripheral current ratio, the inner / outer peripheral current ratio is 100%. Since the heater 16 is controlled by current control, the heating amount for the inner and outer heaters 16a and 16b is adjusted based on the inner / outer current ratio. Is working.

  As is apparent from FIG. 13, in the central portion of the susceptor 15, that is, near the position where the thermocouple is located, the temperature of the susceptor 15 is approximately 1000 ° C. with little dependence on the mixing ratio of the gas constituting the cooling gas flow 3 d. It is kept in. However, the periphery of the susceptor 15 is cooled as the proportion of the hydrogen gas in the cooling gas flow 3d increases, and the temperature of the susceptor 15 decreases, while the temperature in the susceptor 15 decreases as the proportion of nitrogen gas in the cooling gas flow 3d increases. It can be seen that the temperature of the susceptor 15 increases.

  FIG. 14 shows the temperature distribution of the susceptor 15 when the hydrogen gas having a flow rate of 20 L / min is passed as the cooling gas flow 3d and the other conditions are set in the same manner as in FIG. Show. As is apparent from FIG. 14, it was found that the temperature distribution of the susceptor 15 becomes substantially uniform when the inner / outer current ratio is 105%.

  FIG. 15 shows the temperature distribution of the susceptor 15 when the cooling gas flow 3d is set to nitrogen gas with a flow rate of 20 L / min and other conditions are set in the same manner as in FIG. Is shown. As is apparent from FIG. 15, it was found that the temperature distribution of the susceptor 15 becomes substantially uniform when the inner / outer current ratio is 95%.

  As described above, when the same heater is used and heating is performed under the same heating conditions, the temperature distribution of the susceptor 15 changes if the type of gas constituting the cooling gas flow 3d is changed. Therefore, at this time, when the heater has a single configuration, it has been necessary to replace the heater with a devised heater or thickness depending on the growth conditions so as to obtain a uniform temperature distribution.

  Based on the above experimental results, in the fourth embodiment of the present invention, by using the heater 16 divided into at least two or more and setting the current ratio between the heaters appropriately, how the cooling gas flow 3d is changed. Even if it consists of various types of gases, it is possible to obtain a uniform temperature distribution. Therefore, as the heater 16 in the MOCVD apparatus according to the fourth embodiment of the present invention, the heater 16 divided into two parts including the inner peripheral heater 16a and the outer peripheral heater 16b is used as an example.

  In the following, the results of experiments on how the temperature distribution of the susceptor 15 changes depending on the type of gas used for the process gas will be described.

  FIG. 16 shows the temperature distribution of the susceptor 15 when the ratio of hydrogen and nitrogen is changed in the case of flowing a mixed gas composed of hydrogen and nitrogen through the group III gas flow 3b. At this time, hydrogen gas at a flow rate of 20 L / min is flowed through the cooling gas flow 3d, nitrogen gas at a flow rate of 20L / min is flowed through the pressing gas flow 3c, and hydrogen gas at a flow rate of 5L / min is flowed through the V group gas flow 3a. While flowing ammonia at a flow rate of 15 L / min, the set temperature of the susceptor 15, that is, the temperature at the position of the thermocouple is set to 1000 ° C. The inner / outer current ratio is 100%.

  As is clear from FIG. 16, it was confirmed that the temperature in the periphery of the susceptor 15 increased when the proportion of nitrogen in the group III gas flow 3b was increased.

  FIG. 17 shows changes in the temperature distribution of the susceptor 15 when the inner / outer current ratio is changed in the case where nitrogen gas of 20 L / min is passed through the group III gas flow 3b.

  As is apparent from FIG. 17, it was found that the temperature of the susceptor 15 becomes substantially uniform when the inner / outer current ratio is 90%.

  As can be seen from the above experimental results, it is apparent that the temperature distribution of the susceptor 15 changes not only when the type of gas used for the cooling gas but also when the type of process gas is changed. For this reason, in the MOCVD apparatus according to the fourth embodiment of the present invention, an arbitrarily selected cooling gas and process gas are used by using the heater 16 having a divided structure composed of the inner peripheral heater 16a and the outer peripheral heater 16b. Depending on the type, the temperature of the susceptor 15 can be kept uniform. For this reason, it is not necessary to change the winding method or thickness of the heater 16 for each growth condition of each nitride semiconductor grown on the substrate 1A.

  Hereinafter, based on the above experimental results, a method of manufacturing a semiconductor having an LED structure using the MOCVD apparatus according to the fourth embodiment of the present invention will be described.

  FIG. 18 shows a semiconductor layer having an LED structure manufactured by the method for manufacturing a semiconductor layer according to the fourth embodiment of the present invention. That is, as shown in FIG. 18, the low-temperature GaN buffer layer 31 and the GaN layer 32 are grown in order from the bottom on the substrate 1A made of sapphire, and subsequently, the n-type GaN contact layer 33 and the InGaN active layer 34 are grown. Are growing from the bottom up. Further, an electron barrier layer 36 made of AlGaN having a composition ratio of 15% and a thickness of 10 nm is grown immediately above the InGaN active layer 34. A p-type GaN contact layer 35 is grown on the electron barrier layer 36. The LED structure shown in FIG. 18 is a structure intended to increase the efficiency of the LED by providing an electron barrier layer 36 made of AlGaN.

  Below, each process of growing the semiconductor of the LED structure shown in FIG. 18 is demonstrated. Note that the growth method of the same part as the structure shown in FIG. 7 is the same as that described with reference to FIG. 7, and therefore, different points will be mainly described below.

  First, after the substrate 1A is placed on the susceptor 15, a thermal cleaning process is performed. For the purpose of reproducing substantially the same conditions as in the third embodiment of the present invention, the total flow rate is set to 60 L / min. Specifically, nitrogen gas is supplied from the pressure gas inlet 2c at a flow rate of 20 L / min, hydrogen gas is supplied from the group V gas inlet 2a at a flow rate of 20 L / min, and hydrogen gas is supplied from the group III gas inlet 2b at a rate of 20 L / min. The temperature of the susceptor 15 is set to 1000 ° C. while introducing hydrogen gas into the gas introduction pipe 11 at a flow rate of 20 L / min from the cooling gas inlet 2d. Also, the inner / outer current ratio is set to 105%.

  Next, the flow rate of each gas introduced into each introduction port 2a to 2d is maintained as it is, the temperature of the susceptor 15 is set to 500 ° C., and a low temperature is formed on the substrate 1A as in the third embodiment. A GaN buffer layer 31 is grown to 20 nm.

  When the low-temperature GaN buffer layer 31 is grown to 20 nm, the supply of TMG introduced to the group V gas inlet 2a is stopped, and only the ammonia and hydrogen gas are continued while the flow rates of the gas flows 3a to 3d are kept as they are. Supply the temperature of the susceptor 15 to 1000 ° C. When the temperature of the susceptor 15 is stabilized at 1000 ° C., TMG is again introduced into the group V gas inlet 2a to grow the GaN layer 32 by 2 μm.

  Subsequently, while maintaining the flow rates of the gas flows 3a to 3d as they are, a doping gas such as monosilane gas is introduced into the process gas flow channel 12b as in the third embodiment, so that the n-type GaN contact is performed at 1000 ° C. Layer 33 is grown 2 μm. At this time, nitrogen gas flows through the pressing gas flow 3c.

  Next, the temperature of the susceptor 15 is lowered to 770 ° C. while the supply of TMG introduced into the group V gas inlet 2a is stopped and ammonia is still supplied. At this time, the inner / outer current ratio is changed to 95%.

  When the temperature of the susceptor 15 is stabilized, all hydrogen gas introduced into the gas introduction pipe 11 is switched to nitrogen gas. That is, a mixed gas composed of nitrogen gas at a flow rate of 5 L / min and ammonia at a flow rate of 15 L / min is supplied to the group V gas flow 3a. A nitrogen gas having a flow rate of 20 L / min is supplied to the group III gas flow 3b. Nitrogen gas at a flow rate of 20 L / min is passed through the pressing gas flow 3c. The cooling gas flow 3d is supplied with 20 L of nitrogen gas per minute. After maintaining this state for a predetermined time, the InGaN active layer 34 is grown by introducing TMG and trimethylindium (TMI) mixed with the group III gas flow 3b.

  Next, when the InGaN active layer 34 is grown to 5 nm, all the nitrogen gas introduced into the gas introduction tube 11 is switched again to hydrogen gas, and the temperature of the susceptor 15 is raised to 1000 ° C. That is, a mixed gas composed of hydrogen gas at a flow rate of 5 L / min and ammonia at a flow rate of 15 L / min is supplied to the group V gas flow 3a. Hydrogen gas at a flow rate of 20 L / min is passed through the group III gas flow 3b. Hydrogen gas at a flow rate of 20 L / min is passed through the pressing gas flow 3c. Hydrogen gas at a flow rate of 20 L / min is passed through the cooling gas flow 3d.

Next, when the temperature of the susceptor 15 and the gas flow are stabilized, an appropriate ratio of trimethylaluminum (TMA) is introduced together with TMG to grow an electron barrier layer 36 made of AlGaN by 10 nm. Subsequently, TMG and a doping gas such as cyclopentadienylmagnesium (Cp ₂ Mg) are introduced into the process gas flow channel 12b, and a p-type GaN contact layer 35 is grown on the electron barrier layer 36 by 0.2 μm. Let

  Next, when the growth of the p-type GaN contact layer 35 is finished, the supply of the organic metal is stopped, the heater 16 is turned off, and the temperature of the susceptor 15 is lowered. When the temperature of the susceptor 15 reaches 500 ° C., the ammonia introduced into the group V gas flow 3a is switched to hydrogen gas, and the supply of ammonia is also stopped. Further, after the temperature of the susceptor 15 is lowered to near room temperature, the substrate 1A is taken out.

  A blue LED wafer is completed by the above growth process.

  FIG. 19 shows the dependence of the Al composition ratio in the wafer on the inner and outer peripheral currents in the electron barrier layer 36 made of AlGaN. Specifically, the gas flow conditions for growing the electron barrier layer 36 are as described above. It shows the relationship between the Al composition ratio (%) and the wafer position when the inner and outer peripheral current ratio is changed under the same conditions.

  As can be seen from FIG. 19, when the inner / outer current ratio under the same conditions as the growth conditions of the electron barrier layer 36 is 105%, the Al composition ratio is uniform in the wafer. However, when the inner / outer current ratio is changed, it can be seen that the distribution of the Al composition ratio increases. This result corresponds to the fact that when the temperature increases, Ga evaporates and the Al composition ratio increases, whereas when the temperature decreases, Ga evaporation is suppressed and the Al composition ratio decreases. In the semiconductor manufacturing method according to the present embodiment, when the electron barrier layer 36 made of AlGaN is grown, the inner / outer peripheral current ratio is set to 105%, whereby a uniform Al composition ratio can be obtained in the wafer.

  FIG. 20 shows the dependence of the emission wavelength of the InGaN active layer 34 on the inner and outer peripheral currents in the wafer. Specifically, the gas flow conditions for growing the InGaN active layer 34 are the same as those described above. The relationship between the PL emission wavelength (nm) and the position of the wafer when the inner / outer current ratio is changed is shown.

  As can be seen from FIG. 20, when the inner / outer current ratio under the same conditions as the growth conditions of the InGaN active layer 34 is 95%, the emission wavelength is uniform within the wafer. However, it can be seen that when the inner / outer current ratio is changed, the distribution of the emission wavelength is expanded. This result corresponds to a decrease in In uptake when the temperature rises, and an increase in In uptake when the temperature decreases. In the semiconductor manufacturing method according to the present embodiment, when the InGaN active layer 34 is grown, the inner / outer current ratio is set to 95%, so that a uniform emission wavelength distribution can be obtained within the wafer.

  In the semiconductor manufacturing method according to the present embodiment, the third embodiment of the present invention described above is used except that the inner and outer peripheral current ratio of the heater 16 is changed to grow the InGaN active layer 34 and the electron barrier layer 36. Since it is almost the same as the semiconductor manufacturing method according to the embodiment, the maintenance cycle is approximately the same about 40 times as in the case of the third embodiment.

  As described above, according to the MOCVD apparatus and the semiconductor layer manufacturing method of the fourth embodiment of the present invention, the growth conditions such as the process gas used and the flow rate thereof are the same as those of other semiconductors. In any growth of an electron barrier layer and an InGaN layer made of AlGaN, which are greatly different from the growth conditions, an electron barrier layer in which the Al composition distribution is uniform in the wafer and an InGaN layer in which the emission wavelength distribution is uniform in the wafer surface Can be grown. Moreover, in the MOCVD apparatus and the semiconductor manufacturing method according to the fourth embodiment of the present invention, as described in the first to third embodiments of the present invention, the effects of the cooling gas flow 3d and the pressing gas flow 3c. Therefore, the semiconductor having the uniform distribution as described above can be continuously grown stably at a high operation rate, which is very useful for industrial use. In the present embodiment, the case where the semiconductor layer having the LED structure is manufactured has been described. However, the semiconductor device including both AlGaN and InGaN, particularly, a semiconductor device such as a laser or a heterobipolar transistor is manufactured. Needless to say, it is very effective.

  The metalorganic vapor phase epitaxy apparatus and semiconductor layer manufacturing method according to the present invention provide a method for growing a group III nitride semiconductor with good reproducibility and efficiently manufacture a semiconductor device using a group III nitride semiconductor. Useful for that.

1 is a schematic view showing a configuration of a metal organic vapor phase growth apparatus according to a first embodiment of the present invention. It is the schematic for demonstrating the structure of the flow channel in the 1st Embodiment of this invention. It is the schematic for demonstrating the modification of the structure of the flow channel in the 1st Embodiment of this invention. It is sectional drawing which shows the structure of the semiconductor layer grown by the manufacturing method of the semiconductor which concerns on the 1st Embodiment of this invention. It is a related figure of the reflection spectrum intensity | strength and the frequency | count of a growth about the case where it does not flow through the case where nitrogen gas is flowed into the cooling gas flow in the 1st Embodiment of this invention. It is a relationship figure of the reflection spectrum intensity | strength and the frequency | count of growth about the case where the cooling gas flow in the 2nd Embodiment of this invention consists of hydrogen gas, and the case where it consists of nitrogen gas. It is sectional drawing which shows the structure of the semiconductor layer grown with the manufacturing method of the semiconductor which concerns on the 2nd Embodiment of this invention. It is a relationship diagram of photoluminescence (PL) intensity | strength and the wavelength about the case where the cooling gas used at the time of the growth of the InGaN active layer in the 2nd Embodiment of this invention consists of hydrogen gas, and the case where it consists of nitrogen gas. FIG. 10 is a relationship diagram between the reflection spectrum intensity and the number of times of growth when the cooling gas flow used in the growth of the InGaN active layer in the second embodiment of the present invention is made of hydrogen gas and when made of nitrogen gas. It is the schematic which shows the structure of the metal organic vapor phase epitaxy apparatus which concerns on the 3rd Embodiment of this invention. It is a relationship figure of the reflection spectrum intensity | strength and the frequency | count of growth in the 3rd Embodiment of this invention. It is the schematic which shows the structure of the metal organic vapor phase epitaxy apparatus which concerns on the 4th Embodiment of this invention. In the 4th Embodiment of this invention, when the cooling gas flow consists of mixed gas of nitrogen gas and hydrogen gas, it is the relationship figure of the surface temperature of a susceptor when the mixing ratio is changed, and the position of a susceptor. is there. In the 4th Embodiment of this invention, when a cooling gas flow consists of hydrogen gas, it is a related figure of the surface temperature of a susceptor when the inner-outer periphery current ratio is changed, and the position of a susceptor. In the 4th Embodiment of this invention, when a cooling gas flow consists of nitrogen gas, it is a related figure of the surface temperature of a susceptor when the inner-outer periphery current ratio is changed, and the position of a susceptor. It is a related figure between the surface temperature of a susceptor and the position of a susceptor when the mixing ratio of the hydrogen gas and nitrogen gas of a group III gas flow in the 4th Embodiment of this invention is changed. FIG. 10 is a relationship diagram between the surface temperature of the susceptor and the position of the susceptor when the inner / outer current ratio is changed when the group III gas flow is made of nitrogen gas in the fourth embodiment of the present invention. It is sectional drawing which shows the structure of the semiconductor layer grown by the manufacturing method of the semiconductor which concerns on the 4th Embodiment of this invention. It is a related figure of Al composition ratio of an electron barrier layer which consists of AlGaN in a 4th embodiment of the present invention, and a wafer position. It is a related figure of PL light emission wavelength of InGaN and a wafer position in a 4th embodiment of the present invention. It is sectional drawing which shows the structure of the MOCVD apparatus which concerns on a 1st prior art example. It is sectional drawing which shows the structure of the MOCVD apparatus which concerns on a 2nd prior art example.

Explanation of symbols

1A Substrate 2a Group V gas inlet 2b Group III gas inlet 2c Pressed gas inlet 2d Cooling gas inlet 3a Group V gas flow 3b Group III gas flow 3c Pressed gas flow 3d Cooling gas flow 10 Chamber 11 Gas inlet pipe 12 Flow Channel 12a, 12d Flow channel base 12b Process gas flow channel 12c Cooling gas flow channel 12e Heat shield plate 13 Exhaust pipe 14 Rotating shaft 15 Susceptor 16 Heater 17 Observation window 18 Film thickness measuring device 18a White light 19 Rotation angle detection mechanism 20 Rotation signal Cable 21 Temperature distribution measuring device 31 Low-temperature GaN buffer layer 32 GaN layer 33 n-type GaN contact layer 34 InGaN active layer 35 p-type GaN contact layer 36 electron barrier layer

Claims (36)

A chamber for holding the substrate on a susceptor disposed therein;
A cooling gas introduction port that is provided from the wall portion of the chamber to the inside and introduces a cooling gas into the chamber;
A process gas introduction port that is provided independently from the cooling gas introduction port from the wall portion of the chamber to the inside, and introduces a source gas into the chamber;
A process gas flow channel provided so as to be continuous from the process gas inlet, and transporting the source gas introduced from the process gas inlet onto the substrate;
The metal-organic vapor phase epitaxy apparatus, wherein the cooling gas inlet is installed at a position where the cooling gas hits an outer wall of the process gas flow channel. The process gas inlet has a first inlet for introducing a group V gas and a second inlet for introducing a group III gas;
2. The metal organic chemical vapor deposition apparatus according to claim 1, wherein the first inlet and the second inlet are separated from each other up to the vicinity of the process gas flow channel.   The metal-organic vapor phase epitaxy apparatus according to claim 2, wherein the first introduction port and the second introduction port are installed in this order from the side closer to the susceptor.   The metal-organic vapor phase epitaxy apparatus according to claim 1, wherein the cooling gas inlet is installed so as to overlap the process gas inlet.   The organometallic vapor phase growth apparatus according to claim 1, further comprising a cooling gas flow channel provided continuously from the cooling gas introduction port.   The metal-organic vapor phase epitaxy apparatus according to claim 5, wherein the cooling gas flow channel is installed to overlap the process gas flow channel.   6. The metalorganic vapor phase epitaxy apparatus according to claim 5, wherein the cooling gas flow channel is made of quartz.   6. The metal organic chemical vapor deposition apparatus according to claim 5, wherein the process gas flow channel is made of quartz. The process gas inlet has a first inlet for introducing a group V gas, a second inlet for introducing a group III gas, and a third inlet for introducing a pressure gas,
The said 1st inlet, the said 2nd inlet, and the said 3rd inlet are isolate | separated from each other to the vicinity of the said process gas flow channel. Metalorganic vapor phase epitaxy equipment.   10. The organometallic vapor phase according to claim 9, wherein the first introduction port, the second introduction port, and the third introduction port are installed in this order from a side closer to the susceptor. Growth equipment. A heater for heating the substrate;
The metal organic vapor phase epitaxy apparatus according to claim 1, wherein the heater has a structure divided into at least two or more.   The metal-organic vapor phase epitaxy apparatus according to claim 11, wherein the heater is divided into concentric circles.   12. The metal organic chemical vapor deposition apparatus according to claim 11, wherein each of the heaters controls electric power independently of each other.   2. The metal organic chemical vapor deposition apparatus according to claim 1, further comprising an apparatus provided outside the chamber and irradiating the substrate with light through the process gas flow channel.   The metal-organic vapor phase epitaxy apparatus according to claim 14, wherein the light irradiation apparatus is an apparatus for measuring a film thickness of the substrate.   15. The metal organic chemical vapor deposition apparatus according to claim 14, wherein the light irradiation device operates in synchronization with the rotation of the substrate.   The metal organic vapor phase epitaxy according to claim 1, further comprising a device that is provided outside the chamber and measures infrared rays from the substrate or the susceptor through the process gas flow channel. apparatus.   18. The metalorganic vapor phase epitaxy apparatus according to claim 17, wherein the infrared measuring device is a device that measures the temperature of the susceptor. A source gas introduced from a process gas inlet provided from the wall of the chamber to the inside is provided on a substrate held on a susceptor disposed in the chamber so as to be continuous from the process gas inlet. A semiconductor manufacturing method for growing a semiconductor on the substrate by carrying it through a process gas flow channel, comprising:
A method for producing a semiconductor, comprising: growing the semiconductor while applying a cooling gas introduced from a cooling gas inlet provided from a wall portion of the chamber to an inside thereof against an outer wall of the process gas flow channel. The source gas introduced from the process gas inlet includes a group III gas and a group V gas,
20. The method of manufacturing a semiconductor according to claim 19, wherein the group III gas and the group V gas are introduced separately from each other up to the vicinity of the process gas flow channel.   21. The semiconductor manufacturing method according to claim 20, wherein the group III gas and the group V gas are separately introduced in this order from a side close to the susceptor.   The method of manufacturing a semiconductor according to claim 21, wherein the group V gas includes ammonia gas.   20. The semiconductor according to claim 19, wherein the cooling gas is introduced into a cooling gas flow channel that is continuous from the cooling gas inlet and is provided so as to overlap the process gas flow channel. Production method.   The method for manufacturing a semiconductor according to claim 19, wherein the cooling gas is hydrogen gas.   The semiconductor manufacturing method according to claim 19, wherein the cooling gas is nitrogen gas.   When growing a group III nitride semiconductor containing no In as the semiconductor, the cooling gas made of a gas containing hydrogen gas is used, and when growing a group III nitride semiconductor containing In as the semiconductor 20. The method of manufacturing a semiconductor according to claim 19, wherein the cooling gas made of nitrogen gas is used. The source gas introduced from the process gas inlet includes a group III gas, a group V gas, and a pressing gas,
The semiconductor manufacturing method according to claim 19, wherein the group III gas, the group V gas, and the pressing gas are introduced separately from each other up to the vicinity of the process gas flow channel.   28. The method of manufacturing a semiconductor according to claim 27, wherein the group III gas, the group V gas, and the pressing gas are separately introduced in this order from a side close to the susceptor.   29. The method of manufacturing a semiconductor according to claim 28, wherein the group V gas includes ammonia gas.   The method of manufacturing a semiconductor according to claim 28, wherein the pressing gas contains nitrogen gas. The heater provided for heating the substrate has a structure that is divided into at least a first heater and a second heater in order from the inside on a concentric circle,
The semiconductor is grown while changing the electric power applied to each of the first heater and the second heater in accordance with a ratio of hydrogen gas contained in the cooling gas. A method for producing a semiconductor as described in 1.   32. The power applied to the second heater is reduced compared to the power applied to the first heater when increasing the proportion of the hydrogen gas contained in the cooling gas. A method for producing a semiconductor as described in 1.   32. The method according to claim 31, wherein when increasing the ratio of nitrogen gas contained in the cooling gas, the power applied to the second heater is increased as compared with the power applied to the first heater. The manufacturing method of the semiconductor described. The heater provided to heat the substrate has a structure in which the heater is divided into at least a first heater and a second heater in order from the inside on a concentric circle,
The semiconductor is grown while changing electric power applied to each of the first heater and the second heater in accordance with a ratio of hydrogen gas contained in the source gas. A method for producing a semiconductor as described in 1.   35. The power applied to the second heater is reduced compared to the power applied to the first heater when increasing the proportion of the hydrogen gas contained in the source gas. A method for producing a semiconductor as described in 1.   35. The method according to claim 34, wherein when increasing the proportion of nitrogen gas contained in the source gas, the power applied to the second heater is increased as compared to the power applied to the first heater. The manufacturing method of the semiconductor described.