JP4962829B2 - Epitaxial wafer manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing an epitaxial wafer in which a group III nitride compound semiconductor layer is epitaxially grown on a growth substrate.

Japanese Patent Laid-Open No. 10-70076 JP-A-11-260735

  As is well known, compound semiconductor multilayer structures are applied to light-emitting elements such as light-emitting diodes and lasers, ultra-high-speed transistors such as MESFETs (Metal-Semiconductor Field Effect Transistors) and HEMTs (High Electron Mobility Transistors). Has led to the acquisition. In particular, the latter ultrahigh-speed transistor, which uses a GaAs / AlGaAs heterojunction, has been put into practical use and is widely used as a low-noise element for satellite broadcast receivers due to its excellent microwave and millimeter wave characteristics. ing. Here, in order to realize a high-performance ultrahigh-speed transistor, it is indispensable to use a high resistivity substrate in order to suppress the leakage current to the substrate portion as much as possible. In a GaAs / AlGaAs heterojunction, a semi-insulating GaAs single crystal substrate can be manufactured relatively easily, which is one of the causes of widespread use of devices such as ultrahigh-speed transistors.

  On the other hand, there is a heterojunction structure using a GaN-based compound as a semiconductor multilayer structure that has attracted attention in recent years. GaN-based compounds have a band gap that can be changed from 2.0 eV to 6.2 eV at room temperature and are chemically stable, and thus are applied to light-emitting elements such as blue and are becoming popular. In addition to the wide band gap, GaN-based compounds have high electron mobility and can easily form heterojunctions, so they can operate in high-temperature environments. Application to next-generation ultrahigh-speed transistors is also attracting attention, and research is being repeated.

  The element layer is grown by the group III nitride compound by vapor phase growth using a sapphire (single crystal alumina) substrate or a SiC single crystal substrate as a growth substrate. When manufacturing efficiency is taken into consideration, the MOVPE (Metal-Organic Vapor Phase Epitaxy) method is generally used as the vapor phase growth method. At this time, in order to alleviate the lattice mismatch between the substrate and the element layer, a buffer layer made of a group III nitride is grown on the substrate at a relatively low temperature, and then the group III nitride element layer is epitaxially grown. Thus, the quality of the element layer is improved.

  According to Patent Document 1 or Patent Document 2, the buffer layer grown at a low temperature may be decomposed when the element layer is grown at a high temperature thereafter. If the buffer layer, which is the base for crystal growth, is decomposed, the crystal quality of the element layer grown thereafter will be adversely affected. In order to solve this problem, Patent Document 2 proposes that a buffer layer is constituted by a plurality of single crystal grains having a spindle-shaped cross-sectional shape. It is said that the thermal dissociation can be suppressed by forming the buffer layer in such a form.

  However, depending on the type of device using a group III nitride compound semiconductor, a relatively thin group III nitride compound semiconductor layer (hereinafter referred to as a “thin surface layer”) is formed on the outermost layer of the wafer at the final stage of the vapor phase growth process. (For example, in the case of MESFET or HEMT, a Schottky junction formation layer provided immediately below the gate electrode, an ohmic contact formation layer with the source / drain electrode, or the like). After the growth of the thin surface layer, the supply of the source gas into the reaction vessel is stopped and the wafer is cooled as it is in the vessel, but the temperature in the vessel is still high immediately after the supply of the source gas is stopped, Nitride forming a thin surface layer decomposes during cooling. Even if the layer loss due to this decomposition seems to be small at first glance from the thickness of the entire element layer, if the target layer thickness of the thin surface layer to be obtained is small, it is relatively difficult to ignore. Appearing and may cause serious adverse effects on device characteristics such as fluctuations in threshold voltage. The thin surface layer needs to be an epitaxial growth layer that is continuous in the in-plane direction as a part of the device, and it is impossible to suppress decomposition by controlling the form of the polycrystalline layer like the buffer layer.

  An object of the present invention is to provide an epitaxial wafer manufacturing method capable of effectively preventing a deviation from a target layer thickness of a surface thin layer during cooling when forming a surface thin layer made of a group III nitride compound. There is.

Means for Solving the Problems and Effects of the Invention

In the present invention, a growth substrate is placed in a reaction vessel, an organic metal gas of the Group III metal is diluted with a carrier gas as a Group III metal source, and an MOVPE method using an ammonia gas as a nitrogen source is used for III. An epitaxial wafer manufacturing method for epitaxially growing a group nitride compound semiconductor layer on a growth substrate,
A body layer growth step of growing a body layer made of a group III nitride compound on the growth substrate at a first temperature;
A thin surface layer made of a non-doped group III nitride compound for facilitating formation of a Schottky barrier on the main body layer and having a thickness smaller than that of the main body layer is lower than the first temperature. By growing at two temperatures, a surface thin layer growth step for obtaining an epitaxial wafer in which the surface thin layer becomes the wafer outermost surface portion,
A cooling step of stopping the supply of the organometallic gas into the reaction vessel after growing the thin surface layer, and cooling the epitaxial wafer from the second temperature in the reaction vessel in a state where the supply of ammonia gas is continued; In this order ,
The first temperature is set to 1050 ° C to 1100 ° C, the second temperature is set to 1000 ° C to 1050 ° C, and the difference between the first temperature and the second temperature is set to 20 ° C to 100 ° C. characterized in that that. According to this, the cooling start temperature of the surface thin layer can be lowered by lowering the growth temperature (second temperature) of the surface thin layer lower than the growth temperature (first temperature) of the main body layer as a base. In addition, it is possible to suppress the loss due to the decomposition of the thin surface layer. Also, the skin layer in the skin layer growth step, to finally obtain should target thickness, thickness reduction of the surface thin layer produced by decomposition of the nitride forming the surface thin layer during the cooling step Therefore, the growth time of the thin surface layer can be extended by an amount corresponding to the increased thickness.

When the growth time of the surface thin layer is extended as described above, by growing the compensation thickness to compensate for the decrease in the thickness of the surface thin layer, it is possible to grow the surface thin layer during cooling after growth. Even if the loss due to the decomposition occurs, the addition of the compensation thickness can effectively prevent the layer thickness from being insufficient with respect to the target thickness.

Further , the growth substrate is placed in a reaction vessel, and an organic metal gas of the Group III metal as a Group III metal source is a carrier gas mainly composed of either hydrogen or an inert gas (50% of the total partial pressure of the carrier gas). The group III nitride compound semiconductor layer is epitaxially grown on the growth substrate by the MOVPE method using ammonia gas as a nitrogen source. An epitaxial wafer manufacturing method comprising:
A body layer growth step for growing a body layer made of a group III nitride compound on a growth substrate;
On the main body layer, by growing a thin surface layer made of a group III nitride compound and having a thickness smaller than that of the main body layer, the surface thin film is obtained to obtain an epitaxial wafer in which the thin surface layer becomes the outermost surface portion of the wafer. Layer growth process;
In this order, the epitaxial wafer is cooled from the second temperature in the reaction vessel in a state where the supply of the organometallic gas into the reaction vessel is stopped after growing the thin surface layer, and in this order,
The cooling process can also be performed by setting the supply partial pressure of the gas serving as the hydrogen source in the reaction vessel to be lower than that of the surface thin layer growth process.

  The reason why the group III nitride forming the surface thin layer decomposes upon cooling is that the partial pressure of nitrogen in the vicinity of the growth temperature (for example, 900 ° C. to 1100 ° C.) of the nitride by the MOVPE method is high. In this case, after the growth of the thin surface layer, if the cooling is performed while the supply of the organometallic gas is stopped and the circulation of the ammonia gas serving as the nitrogen source is continued, the decomposition of the nitride forming the grown thin surface layer may be seen at a glance. It seems to be able to suppress. However, as a result of investigation by the present inventor, due to the balance between the chemical equilibrium of the decomposition reaction of nitride and the dissociation equilibrium of ammonia molecules that are nitrogen sources, the distribution of hydrogen-containing molecules (especially ammonia molecules and hydrogen molecules) in the atmosphere. It was found that the higher the pressure, the more the nitride decomposition reaction was promoted. As a result, although the decomposition suppression effect due to the ammonia circulation cooling is hardly present, the decomposition of the nitride is promoted, and the thickness control of the surface thin layer becomes more difficult.

According to this , the cooling process is performed with the supply partial pressure of the gas serving as the hydrogen source in the reaction vessel set lower than that of the surface thin layer growth process, so the surface thin layer is reduced by the decomposition of nitride during cooling. Can be effectively suppressed.

  In this case, as described above, ammonia circulation cooling tends to promote nitride decomposition. Therefore, the cooling process can be carried out by setting the supply partial pressure of ammonia gas in the reaction vessel to be lower than that of the surface thin layer growth process, and effectively suppresses the thinning of the surface thin layer due to nitride decomposition. Can do.

  It is also effective to carry out the cooling step while continuing to supply the carrier gas to the reaction vessel, and to increase the inert gas partial pressure of the carrier gas in the cooling step as compared to the surface thin layer growth step. By increasing the inert gas partial pressure during cooling, the effect of suppressing the decomposition of the nitride forming the thin surface layer can be further enhanced. In the surface thin layer growth step, it is possible to use a carrier gas whose hydrogen gas partial pressure is higher than the inert gas partial pressure (including the case where no inert gas is contained). May be advantageous in terms of promoting It is possible to continue the flow of the carrier gas and proceed to the cooling process. In this case, it is possible to reduce the partial pressure of the hydrogen gas (in the carrier gas) by reducing the surface layer due to the decomposition of nitride. It is effective in suppressing the loss of eyes.

  In the above method, it is desirable to use nitrogen gas as the inert gas. Thereby, in the cooling step, the partial pressure of nitrogen molecules that are the decomposition products of nitride can be increased, and the chemical equilibrium of the nitride decomposition reaction shifts in the direction of suppressing decomposition, so that the effect of the present invention can be further enhanced. it can. Further, in the present invention, as an inert gas other than nitrogen, a rare gas such as Ar gas can be used (“inert gas” refers only to a rare gas in a narrow sense, but in the present invention, “inert gas”). The concept of “gas” includes nitrogen gas).

Further , the growth substrate is placed in a reaction vessel, and the Group III metal organometallic gas is diluted with a carrier gas as the Group III metal source, and the Group III nitridation is performed by the MOVPE method using ammonia gas as the nitrogen source. An epitaxial wafer manufacturing method for epitaxially growing a physical compound semiconductor layer on a growth substrate,
A body layer growth step for growing a body layer made of a group III nitride compound on a growth substrate;
On the main body layer, by growing a thin surface layer made of a group III nitride compound and having a thickness smaller than that of the main body layer, the surface thin film is obtained to obtain an epitaxial wafer in which the thin surface layer becomes the outermost surface portion of the wafer. Layer growth process;
After the growth of the thin surface layer, the supply of the organometallic gas to the reaction vessel is stopped, and the cooling process for cooling the epitaxial wafer in the reaction vessel is performed in this order while the supply of ammonia gas is continued. And
Using an inert gas as a carrier gas in the surface thin layer growth step, it is also possible to carry out cooling while continuing the supply of inert gas in the cooling step.

According to this , since the cooling process is carried out in a state in which the supply of the inert gas is continued using the carrier gas made of the inert gas in the surface thin layer growth process, the surface thinning due to the decomposition of nitride during cooling is performed. The loss of the layer can be effectively suppressed. Again, it is desirable to use nitrogen gas as the inert gas. Thereby, in the cooling step, the partial pressure of nitrogen molecules that are the decomposition products of nitride can be increased, and the chemical equilibrium of the nitride decomposition reaction shifts in the direction of suppressing decomposition, so that the effect of the present invention can be further enhanced. it can.

  When cooling is performed while circulating ammonia gas, the etching amount generated in the surface thin layer is about 0.5 to several nm, and particularly when the etching amount does not fall within the range of the film thickness tolerance, When the thickness of the thin layer must be set in the range of 1 nm or more and 30 nm or less, the adoption of the present invention is extremely effective.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 schematically shows the structure of a HEMT which is an example of a semiconductor element using the semiconductor multilayer structure of the present invention. The HEMT 1 is obtained by forming a main body layer 103 on a single crystal substrate 101 made of SiC or sapphire via a buffer layer 102 by a heteroepitaxial growth method. The main body layer 103 is formed by laminating an i-GaN layer 105 functioning as an active layer and an n-type AlGaN layer 110 functioning as an electron supply layer in this order from the side close to the buffer layer 102. Furthermore, a thin surface layer 104 made of non-doped AlGaN for facilitating formation of a Schottky barrier is formed thereon. Therefore, the HEMT 1 of this embodiment is an n-channel type, but in the case of a p-channel type, the n-type AlGaN layer 110 may be replaced with a p-type one. A drain electrode 106 and a source electrode 107 (for example, Ti / Al) are formed on the non-doped AlGaN layer 104. Further, the gate electrode 108 is formed of a metal (for example, Pd / Au) that forms a Schottky junction. In order to stabilize the driving characteristics of the gate electrode 108, the layer thickness of the surface thin layer 104 needs to be controlled within a tolerance range of, for example, about 5 nm ± 1 nm. The total thickness of the main body layer 103 is not less than 1 μm and not more than 5 μm. Since the operating principle of the HEMT 1 itself is well known, detailed description is omitted.

Each of the above-described HEMTs 1 is manufactured from an epitaxial wafer obtained by heteroepitaxial growth using a known MOVPE method on a single crystal substrate 1 through a buffer layer 102. Hereinafter, the manufacturing method of the epitaxial wafer according to the present invention will be described in detail. As shown in step 1 of FIG. 2, the sapphire substrate 10 is set in the reaction vessel. Then, a buffer layer 11 made of GaN is epitaxially grown on the sapphire substrate 10. Then, the main body layer 103 is epitaxially grown on the buffer layer 11. The epitaxial growth of each of these layers can be performed by the MOVPE method as described above. The inside of the reaction vessel is heated to a growth temperature (for example, 900 ° C. or more and 1100 ° C. or less) by a heating source (in this embodiment, an infrared lamp). The following can be used as the main raw material of each layer.
Al source gas; trimethylaluminum (TMAl), triethylaluminum (TEAl), etc .;
Ga source gas; trimethylgallium (TMGa), triethylgallium (TEGa), etc .;
Nitrogen source gas: ammonia (NH ₃ );
Acceptor impurities (Mg): cyclopentadienyl Mg, methylpentadienyl Mg, etc .;
Donor impurity (Si): monosilane, disilane, tetraethylsilane, etc.

  An organic metal (MO) serving as a metal source is accommodated in a metal MO reservoir 203, and a carrier gas composed of hydrogen gas or nitrogen gas (or a mixture of both) is introduced into the MO reservoir 203, so that the inside The organic metal is extruded into the supply pipe in a form diluted with a carrier gas, and supplied into the reaction vessel while the flow rate is adjusted by a mass flow controller (MFC). The carrier gas can be supplied to the reaction vessel so as to bypass the MO reservoir 203 by operating the bypass valve 202. Further, by operating the mixing valve 201, it is possible to switch between the supply forms that are either hydrogen gas or nitrogen gas, or to change the supply ratio when both are mixed and supplied. Further, ammonia gas as a nitrogen source and dopant gas are also supplied into the reaction vessel while the flow rate is adjusted by a mass flow controller (MFC), respectively (the supply of dopant gas is stopped when growing a non-doped layer). Not long)

  When the growth of the main body layer 103 is completed, the thin surface layer 104 is grown as shown in Step 2, and then, as shown in Step 3, the operation of the bypass valve 202 stops the supply of the organic metal while flowing only the carrier gas. Then, the layer growth is stopped, and in this state, heating by the infrared lamp is stopped and the temperature is cooled to room temperature. Thereafter, electrodes are formed, and the chip is diced and molded to complete the HEMT 1 shown in FIG.

  FIG. 3 is a conceptual diagram of a gas supply and temperature control sequence conventionally employed by the present inventors when growing a main body layer and a thin surface layer. Only hydrogen gas is used as the carrier gas. After growing the main body layer, a thin surface layer is grown at the same temperature. Then, the supply of the organic metal (MO) is stopped, and the circulation of ammonia gas and hydrogen gas is continued, and the lamp heating is stopped and cooling is performed. .

  When cooling is performed while the circulation of ammonia gas and hydrogen gas is continued, as shown in FIG. 11, the dissociation reaction of ammonia molecules that have been in progress for layer growth into nitrogen molecules and hydrogen molecules is caused by organometallic molecules. Therefore, an attempt is made to maintain the chemical equilibrium in such a way as to promote the nitride decomposition of the already grown thin surface layer. Further, if hydrogen molecules coexist, when considering the dissociation reaction of ammonia molecules, the equilibrium tends to be inclined in the direction of lack of nitrogen molecules, which also promotes nitride decomposition. As a result, a part of the thin skin layer that has been grown is decomposed during cooling, leading to a reduction in the layer thickness.

  Therefore, as shown in FIG. 12, it is preferable to grow the thin surface layer in a form in which the compensation thickness for compensating the reduction thickness required at the time of cooling is increased to the target thickness to be finally obtained (the first thickness). One invention). As a result, even if nitride decomposition occurs during cooling, the overlay of the compensation thickness absorbs this, and a thin surface layer having a target thickness can be obtained. As shown in FIG. 4, the compensation thickness can be increased by extending the growth time of the surface thin layer by an amount corresponding to the increased thickness. It is also possible to increase the supply amount of the source gas or raise the growth temperature).

  On the other hand, as another method, as shown in FIG. 5, the main body layer is grown at the first temperature, and then the skin layer is grown on the main body layer at the second temperature lower than the first temperature. It is also possible to adopt a method of growing, and then stopping the supply of the organometallic gas (MO) and cooling the epitaxial wafer from the second temperature in the reaction vessel in this state (second invention). As shown in FIG. 13, by lowering the growth temperature (second temperature) T2 of the skin layer 104 below the growth temperature (first temperature) T1 of the main body layer serving as the base, the cooling start temperature of the skin layer is reduced. It can be reduced, and the loss due to the decomposition of the thin surface layer can be suppressed. When the first temperature is set to, for example, 1050 ° C. or more and 1100 ° C. or less, the second temperature is preferably set to 1000 ° C. or more and 1050 ° C. or less, and the difference between the first temperature and the second temperature is 20 ° C. The temperature is preferably 100 ° C. or lower. If the difference is less than 20 ° C., the etching suppression effect at the time of cooling the surface thin layer is not sufficient, and if it exceeds 100 ° C., the second temperature is excessively lowered, and the efficiency of the growth reaction of the surface thin layer is remarkably reduced. .

  Even when the second invention is adopted, the etching of the thin surface layer during cooling may occur to some extent. However, if the reduction in the layer thickness due to the etching falls within the tolerance range of the target thickness, the second invention alone can sufficiently solve the problem. If the surface thin layer is grown by combining one invention and increasing the reduced portion, the layer thickness of the surface thin layer can be kept within the tolerance.

  FIG. 6 discloses another method. When a thin gas layer is grown, hydrogen gas is allowed to flow as a carrier gas, and when the cooling process is started, the carrier gas is switched from hydrogen gas to nitrogen gas. At the same time, the supply of ammonia gas is also stopped. As a result, hydrogen is adopted as the carrier gas during the growth of the thin surface layer, so that the layer growth is promoted. On the other hand, in the cooling process, the supply of the gas serving as the hydrogen source is stopped (that is, the distribution process is stopped). Therefore, the etching of the thin surface layer during cooling is greatly suppressed (third invention). It should be noted that the supply amounts of ammonia gas and hydrogen gas are gradually reduced at the time of switching, and nitrogen gas is gradually increased so as not to cause a sudden disturbance in the gas flow during the transition to the cooling process. In the sequence of FIG. 7, the temperature during the growth of the thin surface layer is reduced as compared with that during the growth of the main body layer, thereby further enhancing the effect of preventing the etching of the thin surface layer during cooling (combination of the second invention).

  In the sequence shown in FIG. 8, a carrier gas in which nitrogen gas and hydrogen gas are mixed is used during growth of the main body layer and the thin surface layer, and supply of only hydrogen gas together with ammonia gas is stopped during cooling. In this case as well, the partial pressure of the gas serving as the hydrogen source is still reduced in the cooling process. In addition, the composition of the carrier gas is such that the hydrogen gas partial pressure prevails during the growth of the main body layer (including the composition that becomes 100% hydrogen), and the nitrogen gas partial pressure predominates during the thin surface layer growth. Can be employed (including a composition that becomes 100% nitrogen), and the etching efficiency of the thin surface layer can be effectively suppressed while maintaining a high growth efficiency of the body layer having a large layer thickness. .

  Although the layer growth rate is slightly slow, as shown in FIG. 9, it is also possible to employ a method in which only nitrogen gas is used as a carrier gas and cooling is performed while the nitrogen gas is circulated (fourth invention). FIG. 10 is a combination of FIG. 9 and the second and third inventions. The temperature is lowered in the growth process of the thin surface layer, and the supply of ammonia gas is shut off during cooling.

  According to the method disclosed in FIGS. 8 to 10, the main component of the atmosphere during the cooling step is nitrogen gas as shown in FIG. By increasing the partial pressure of nitrogen molecules, which are the decomposition products of nitride, the chemical equilibrium of the nitride decomposition reaction shifts in the direction of suppressing decomposition, so that the decomposition of the surface thin layer 104 is suppressed and the thickness of the layer due to etching is reduced. It can be effectively suppressed.

The results of experiments conducted to confirm the effects of the present invention will be described below. That is, a sapphire substrate is placed in a well-known MOVPE growth apparatus as shown in FIG. 2 to grow a GaN buffer layer having a thickness of 2 μm, and then the growth temperature is set variously and carriers made of hydrogen or nitrogen are used. The gas flow rate is kept constant at 10 L / min and the ammonia gas flow rate is kept constant at 10 L / min, and TMGa which is an organometallic raw material is circulated at 4 × 10 ⁻⁴ L / min for 60 seconds, and then 0 seconds to 60 seconds. By repeating the cycle of stopping circulation for various times of seconds, a GaN layer body having a measurable thickness was grown. Here, paying attention to the progress of the etching of the GaN layer body while stopping the flow of TMGa, the total flow time of TMGa is made constant at each temperature condition, and the total flow stop time is changed. The GaN layer body was grown in various ways. The film thickness of the grown GaN layer body was measured by X-ray diffraction, and the etching amount per minute of the GaN layer was determined from the dependence of the film thickness on the total distribution stop time. In order to measure the thickness of the GaN layer body separately from the underlying GaN buffer layer, a thin AlGaN layer having a thickness of 20 nm was formed as a marker layer between the GaN layer body and the GaN buffer layer. The result of plotting the etching amount against the growth temperature is shown in FIG. According to this, when hydrogen is used as the carrier gas, the etching amount is very large, and the amount of increase in the etching amount with respect to the growth temperature is large. On the other hand, using nitrogen as the carrier gas greatly increases the etching amount. It is clear that the growth temperature dependency is reduced.

The schematic diagram which shows one Embodiment of HEMT obtained based on the epitaxial wafer manufactured by this invention. The figure explaining the outline of the manufacturing process of the epitaxial wafer of this invention. The schematic sequence diagram which shows the prior art example of the gas supply and temperature control form of the process which concerns on the summary of this invention. The schematic sequence diagram which similarly shows the example of 1st invention. The schematic sequence diagram which similarly shows a 2nd invention example. The schematic sequence diagram which similarly shows the 1st example of 3rd invention. The schematic sequence diagram which similarly shows the 2nd example of 3rd invention. The schematic sequence diagram which similarly shows the 3rd example of 3rd invention. The schematic sequence diagram which similarly shows the 1st example of 4th invention. The schematic sequence diagram which similarly shows the 2nd example of 4th invention. FIG. Effect explanatory drawing of a 1st invention. The effect explanatory view of the 2nd invention. Effect explanatory drawing of 3rd invention and 4th invention. The graph which shows the experimental result done in order to confirm the effect of this invention.

Explanation of symbols

103 Body layer 104 Surface thin layer

Claims (3)

A substrate for growth is placed in a reaction vessel, an organic metal gas of the Group III metal is diluted with a carrier gas as a Group III metal source, and a Group III nitride system is used by a MOVPE method using ammonia gas as a nitrogen source. An epitaxial wafer manufacturing method for epitaxially growing a compound semiconductor layer on the growth substrate,
A body layer growth step of growing a body layer made of a group III nitride compound on the growth substrate at a first temperature;
A thin surface layer made of a non-doped group III nitride compound for facilitating formation of a Schottky barrier on the main body layer and having a thickness smaller than the main body layer is lower than the first temperature. By growing at a low second temperature, a surface thin layer growth step for obtaining an epitaxial wafer in which the surface thin layer becomes the wafer outermost surface portion,
Stop the supply of the organometallic gas into the reaction vessel after growing the thin surface layer, and continue the supply of the ammonia gas in the reaction vessel with the second temperature. The cooling process of cooling from the above is carried out in this order ,
The first temperature is set to 1050 ° C. to 1100 ° C., the second temperature is set to 1000 ° C. to 1050 ° C., and the difference between the first temperature and the second temperature is 20 ° C. to 100 ° C. The manufacturing method of the epitaxial wafer characterized by setting to the following . The thickness reduction of the surface thin layer caused by the decomposition of the nitride forming the surface thin layer in the cooling step is reduced with respect to the target thickness to be finally obtained in the surface thin layer growth step. 2. The epitaxial wafer according to claim 1 , wherein the growth time of the surface thin layer is extended by an amount corresponding to the increased thickness in order to grow the compensated thickness to be compensated. Production method. The method of manufacturing an epitaxial wafer according to claim 1 or 2 , wherein the thickness of the thin surface layer is 1 nm or more and 30 nm or less.

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