JP4822457B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for generating a high-power / high-frequency nitride semiconductor element on a silicon substrate.

  Gallium nitride (GaN) single crystal substrates are expensive and only available in small substrate sizes. For this reason, when manufacturing a GaN-based semiconductor device, a nitride semiconductor thin film such as GaN is usually grown on this single crystal growth substrate using a single crystal growth substrate formed of another material.

  A silicon (Si) substrate used as a single crystal growth substrate is inexpensive and a substrate having a large substrate size is available. Therefore, the research using the Si substrate as the crystal growth substrate is actively conducted along with the use of the silicon carbide (SiC) substrate.

  The Si substrate is usually manufactured by a Czochralski (CZ) method, but recently, a floating zone (FZ) method may be used. As a silicon substrate manufactured by the FZ method, a high-resistance Si substrate (for example, HiRes (registered trademark) manufactured by Topsil) having a resistivity of 5 k to 30 kΩ · cm is available.

  As a method for growing a nitride semiconductor thin film such as GaN on a Si substrate, there is a metal organic chemical vapor deposition (MOCVD) method. As a general feature of the MOCVD method, the temperature of the Si substrate (substrate temperature) is increased, and aluminum nitride (AlN) is grown as a buffer layer, and then the substrate temperature is lowered and GaN epitaxial growth is performed. It is known that a thin film with good properties can be obtained. For example, an AlN layer is grown on a Si substrate at a substrate temperature of 1200 [° C.] in a hydrogen atmosphere, and then the substrate temperature is lowered to 1120 [° C.], and then GaN is epitaxially grown, whereby the GaN substrate is formed. Obtained (for example, see Non-Patent Documents 1 and 2).

  Here, it has been confirmed that when the substrate temperature is raised to 1200 [° C.] and an AlN layer is formed on the Si substrate, the resistance value of the Si substrate decreases. This is because gallium (Ga) and aluminum (Al) elements existing in the growth apparatus diffuse into the Si substrate when the temperature is raised (see, for example, Non-Patent Document 3).

  As Ga or Al diffuses into the Si substrate, a p-type low resistance layer is formed on the Si substrate. In a GaN-based high electron mobility transistor (HEMT) formed by growing AlN, AlGaN, and GaN on a Si substrate, the presence of this low resistance layer deteriorates characteristics such as a decrease in cutoff frequency. Bring.

As a method of avoiding the generation of the low resistance layer, there is a method of increasing the resistance by compensating an acceptor formed by MOCVD by ion implantation (see, for example, Patent Document 1).
H. Kondo et al. "Series Resistance in n-GaN / AlN / n-Si Heterojunction Structure", Jpn. J. et al. Appl. Phys. Vol. 45 (2006) 4015 H. M.M. Manasevit et al. , “The Use of Metallurgy in the Preparation of Semiconductor Materials”, J. Am. Electrochem. SOc. , 118 (1971) 1864 P. Rajagopal et al. "MOCVD AlGaN / GaN HFETs on Si: Challenges and Issues", Material Society Symposium Proceedings, 798, 61-66. JP 2007-273649 A

  However, the acceptor level generated by the MOCVD method and the level formed by ion implantation remain in the vicinity of the interface of the Si substrate with the nitride semiconductor layer. This may cause problems such as diffusion of the ion-implanted element into the nitride semiconductor layer. In addition, the high resistance layer formed by ion implantation may cause a problem such as a high threshold voltage.

  Further, since an extra process by ion implantation is required for manufacturing a semiconductor device, it is disadvantageous in terms of cost.

  Therefore, when the inventors of this application have conducted intensive research, when annealing is performed in a nitrogen atmosphere or a hydrogen atmosphere in a growth apparatus that performs MOCVD, the sheet resistance decreases as the substrate temperature increases, That is, it has been found that a decrease in sheet resistance can be suppressed by lowering the substrate temperature.

  Further, it has been found that when the substrate temperature is the same, the resistance value can be prevented from lowering when annealing is performed in a nitrogen atmosphere as compared with the case where annealing is performed in a hydrogen atmosphere.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to manufacture a semiconductor device that suppresses a decrease in the resistance value of an Si substrate when AlN and GaN are grown on the Si substrate. It is to provide a method.

  In order to achieve the above object, according to a first aspect of the present invention, there is provided a semiconductor device manufacturing method including the following steps.

First, a silicon substrate formed by the FZ method and having a resistivity of [6 kΩ · cm] or more is introduced into the growth apparatus, and the silicon substrate is 900 [° C.] to 1000 [° C.] in a hydrogen atmosphere in the growth apparatus . Clean at a temperature in the range . Next, after the inside of the growth apparatus is set to an inert gas atmosphere, the inside of the growth apparatus is decompressed, and the temperature of the silicon substrate is increased to a growth temperature of 1100 [° C.] . Next, a source gas is introduced into the growth apparatus, and an aluminum nitride layer is formed as a buffer layer on the silicon substrate by metal organic vapor phase epitaxy.

In carrying out the above-described method for manufacturing a semiconductor device, preferably, in the step of reducing the pressure in the growth apparatus, the pressure in the growth apparatus is within a range of 6.7 × 10 ^{3 to} 2.7 × 10 ⁴ [Pa]. Good to do.

Further, according to a preferred embodiment of the manufacturing method of the semiconductor device described above, in the step of performing the cleaning, the temperature of the silicon substrate good to you and 1000 [° C.].

  In order to achieve the above-described object, according to a second aspect of the present invention, there is provided a semiconductor device manufacturing method including the following steps.

First, a silicon substrate formed by the FZ method and having a resistivity of [6 kΩ · cm] or more is introduced into the growth apparatus, and the silicon substrate is 900 [° C.] to 1000 [° C.] in a hydrogen atmosphere in the growth apparatus . Clean at a temperature in the range . Next, the inside of the growth apparatus is depressurized. Next, a source gas is introduced into the growth apparatus, and an aluminum nitride layer is formed as a buffer layer on the silicon substrate by metal organic vapor phase epitaxy , and the temperature of the silicon substrate is 1000 [° C.] .

In carrying out the above-described method for manufacturing a semiconductor device, preferably, in the step of reducing the pressure in the growth apparatus, the pressure in the growth apparatus is within a range of 6.7 × 10 ^{3 to} 2.7 × 10 ⁴ [Pa]. Good to do.

Further, according to a preferred embodiment of the manufacturing method of the semiconductor device described above, it is good to the temperature of Oite silicon substrate as engineering for cleaning and 1000 [° C.].

  According to the method of manufacturing a semiconductor device of the present invention, after the temperature of the silicon substrate is raised in a nitrogen atmosphere, an aluminum nitride layer is formed, or the substrate temperature is about 1000 [° C.] in a hydrogen atmosphere. By forming the aluminum layer, the nitride semiconductor can be grown before Ga or Al diffuses into the silicon substrate. As a result, generation of a p-type low resistance layer formed at the interface between the silicon substrate and the nitride semiconductor layer can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments are merely schematically shown to the extent that the present invention can be understood. In the following, a preferred configuration example of the present invention will be described. However, the material and numerical conditions are merely preferred examples. Therefore, the present invention is not limited to the following embodiments, and many changes or modifications that can achieve the effects of the present invention can be made without departing from the scope of the configuration of the present invention.

  First, with reference to FIG. 1, the relationship between annealing temperature and atmospheric gas and sheet resistance will be described. FIG. 1 is a diagram showing the annealing temperature dependence of sheet resistance. In FIG. 1, the horizontal axis represents the annealing temperature [° C.], and the vertical axis represents the sheet resistance [Ω / □].

  An n-type silicon (Si) substrate having a (111) plane as a principal surface, manufactured by a floating zone melting (FZ) method, and having a resistivity ρ of 6 [kΩ · cm] or more Is used.

  In order to remove the natural oxide film on the Si substrate, the Si substrate is immersed in a 12.5% dilute hydrofluoric acid solution for 10 minutes, and then washed with pure water for 20 minutes. Thereafter, a Si substrate was introduced into a metal organic chemical vapor deposition (MOCVD) apparatus and annealed at normal pressure for 10 minutes.

  Here, as the annealing temperature, the silicon substrate temperature (substrate temperature) was set to 900, 1000, 1100, and 1200 [° C.], respectively.

In the case of a hydrogen atmosphere (indicated by ◯ in the figure), the sheet resistance decreases as the annealing temperature increases. For example, when the annealing temperature is 1200 [° C.], the sheet resistance is about 2.5 [kΩ / □] in a hydrogen atmosphere. Here, assuming that gallium (Ga) is uniformly distributed to a depth of 0.5 [μm], when the sheet resistance is 2.5 [kΩ / □], 2 × 10 ¹⁷ [atoms / The presence of carriers of about cm ³ ] is considered.

  Also in the case of a nitrogen atmosphere (indicated by-in the figure), the sheet resistance decreases as the annealing temperature increases, as in the hydrogen atmosphere. Here, when the annealing temperature is the same, the sheet resistance decreases less when the annealing is performed in a nitrogen atmosphere than when the annealing is performed in a hydrogen atmosphere. For example, when the annealing temperature is 1200 [° C.], the sheet resistance is about 7 [kΩ / □] in a nitrogen atmosphere.

(First embodiment)
With reference to FIG. 2, the manufacturing method of the semiconductor device of 1st Embodiment is demonstrated. FIG. 2 is a diagram for explaining a method of manufacturing a semiconductor device. The horizontal axis indicates time t, and the vertical axis indicates substrate temperature [° C.].

  Here, an n-type Si substrate having a (111) plane as a main surface and manufactured by the FZ method and having a resistivity ρ of 6 [kΩ · cm] or more is used as the growth substrate.

  First, in order to remove the natural oxide film formed on the Si substrate, the Si substrate is immersed in a 12.5% dilute hydrofluoric acid solution for 10 minutes and then washed with pure water for 20 minutes.

  Next, the cleaned Si substrate is introduced into the MOCVD apparatus as a growth apparatus.

  Next, the surface of the Si substrate is cleaned in the growth apparatus. The cleaning of the surface of the Si substrate is performed in a hydrogen atmosphere at a substrate temperature of 900 [° C.] or higher, preferably 1000 [° C.]. In the following description, the substrate temperature at the time of cleaning may be referred to as a cleaning temperature.

In cleaning the surface of the Si substrate, first, the inside of the growth apparatus is set to a hydrogen atmosphere (H ₂ ) at normal pressure (NP), and then the temperature is raised to the cleaning temperature over 5 minutes from time t0 to t1. Thereafter, the cleaning temperature is maintained for 10 minutes from time t1 to t2, and the surface of the Si substrate is cleaned.

Next, the atmosphere in the growth chamber is replaced with a nitrogen atmosphere (N ₂ ) from a hydrogen atmosphere (H ₂ ). In a normal MOCVD apparatus, the time required to replace the atmosphere is about several seconds. Here, after the gas introduced into the MOCVD apparatus is switched from hydrogen gas to nitrogen gas, the apparatus waits for one minute from time t2 to t3. Here, nitrogen gas is used to form a nitrogen atmosphere. However, it may be chemically inert at 1000 to 1200 [° C.], and an inert gas atmosphere may be formed using a rare gas such as argon gas. good.

Next, at time t3, the pressure in the growth chamber is in the range of 6.7 × 10 ^{3 to} 2.7 × 10 ⁴ [Pa] (50 to 200 [Torr]), preferably 1.3 × 10 ^4. The pressure is reduced to [Pa] (100 [Torr]).

  Next, the substrate temperature is raised to the growth temperature. This growth temperature is the substrate temperature when an AlN layer as a buffer layer, a GaN layer as a channel layer, and an AlGaN layer as a barrier layer are epitaxially grown in this order on a Si substrate. The growth temperature is conventionally about 1200 [° C.], but here the growth temperature is 1100 [° C.]. The temperature rise from the cleaning temperature to the growth temperature is performed over 3 minutes from time t3 to t4.

Next, a source gas is introduced into the growth apparatus, and an AlN layer is formed on the Si substrate by MOCVD. As a source gas for forming the AlN layer, trimethylaluminum (TMA) as an organic metal is introduced at a flow rate of, for example, 5 [μmol / min], and ammonia (NH ₃ ) is, for example, 5 [SLM (Standard l / min). ] At a flow rate of At this time, together with TMA and ammonia, a carrier gas is introduced at a flow rate of, for example, 14 [SLM].

  Here, since the growth chamber has a nitrogen atmosphere in the depressurization and temperature raising steps, the carrier gas can be used as it is. However, when nitrogen gas is used as the carrier gas, the growth rate of the AlN layer is about 1/10 compared to when the carrier gas is hydrogen gas. For this reason, when introducing the source gas, it is preferable to switch the carrier gas to hydrogen gas. The carrier gas is switched from nitrogen gas to hydrogen gas simultaneously with the introduction of the source gas or after the start of the introduction of the source gas.

  Although the example in which the buffer layer is an AlN layer has been described here, the present invention is not limited to this example. It is sufficient if a good GaN crystal can be formed on the buffer layer, and a nitride semiconductor layer such as AlGaN may be formed as the buffer layer.

  After forming the buffer layer, a GaN layer as a channel layer and an AlGaN layer as a barrier layer are sequentially formed. Here, when the GaN layer is formed, trimethylgallium (TMG) may be introduced as an organic metal instead of TMA. Moreover, when forming an AlGaN layer, TMA and TMG may be introduced as organic metals.

  After the growth of the buffer layer, channel layer, and barrier layer, the carrier gas is switched from hydrogen to nitrogen while introducing ammonia, and the temperature is lowered to 200 ° C. over a period of about 15 minutes from time t5 to t6. Here, when the temperature is lowered to 400 ° C., the supply of ammonia is stopped.

  Thereafter, a device may be produced by an ordinary transistor manufacturing process for an AlGaN / GaN heterostructure in which an AlGaN layer as a barrier layer is formed on a GaN layer as a channel layer. The transistor manufacturing process will be briefly described below.

A silicon oxide film (SiO ₂ film) as a mask material is formed on the AlGaN / GaN heterostructure by, for example, a plasma CVD method, and then a resist pattern is formed on the SiO ₂ film by photolithography. Wet etching is performed using this resist pattern as a mask to pattern the SiO ₂ film. Next, element isolation is performed by ion implantation with argon or the like using the patterned SiO ₂ film as a mask.

  Next, a resist pattern having openings in regions where source and drain electrodes are to be formed is formed by photolithography. Thereafter, after Tl / Al is deposited, lift-off is performed. Thereafter, heat treatment is performed at 600 [° C.] to obtain an electrode having ohmic characteristics.

  Next, a resist pattern having an opening in a region where a gate electrode is to be formed is formed by photolithography. Then, after depositing Ni / Au, lift-off is performed, and further a heat treatment of 400 [° C.] is performed to obtain a gate electrode.

  With reference to FIG. 3, the relationship between the atmosphere at the time of raising the temperature to the growth temperature and the sheet resistance will be described. FIG. 3 is a diagram showing the carrier gas dependence of the sheet resistance. In FIG. 3, the horizontal axis indicates the growth temperature [° C.], and the vertical axis indicates the sheet resistance [Ω / □].

  When the growth temperature is 1100 [° C.] and the temperature is raised to the growth temperature in a hydrogen atmosphere, the sheet resistance is 9 [kΩ / □] or less. On the other hand, as shown in the first embodiment, when the growth temperature is similarly set to 1100 [° C.] and the temperature is raised to the growth temperature in a nitrogen atmosphere, the sheet resistance becomes 18 [kΩ / □]. This value is more than twice as large as when the temperature is raised in a hydrogen atmosphere.

  Further, when the sheet resistance is larger than 10 [kΩ / □], the cutoff frequency is 11 [GHz], which is sufficient for use in an S-band power amplifier of 2 to 4 [GHz].

FIG. 4 shows the results of backside SIMS analysis when an AlN layer is grown on a high-resistance Si substrate in a nitrogen atmosphere with a growth temperature of 1100 [° C.] and a hydrogen atmosphere with 1200 [° C.]. In FIG. 4, the horizontal axis indicates the depth [μm] from the surface of the AlN layer, and the vertical axis indicates the Ga concentration [atoms / cm ³ ]. Here, the backside SIMS is a component analysis method in which secondary ion mass spectrometry is performed while sputtering from the back surface of the substrate. When backside SIMS is used, the knock-on effect when sputtering is performed from the surface can be eliminated.

When an AlN layer is grown under conditions of a hydrogen atmosphere and a growth temperature of 1200 [° C.] (indicated by I in FIG. 4), the Ga concentration is 1 × 10 ¹⁶ [in the vicinity of the interface between the Si substrate and the AlN layer. atoms / cm ³ ] or more, and 1 × 10 ¹⁵ [atoms / cm ³ ] or more up to a depth of about 0.7 [μm].

On the other hand, when the AlN layer is grown under conditions of a nitrogen atmosphere and a growth temperature of 1100 [° C.] (indicated by II in FIG. 4), the Ga concentration is 1 × 10 5 near the interface with the AlN layer of the Si substrate. ¹⁶ [atoms / cm ³ ] or more, but at a depth of 0.3 [μm] or more, it is almost below the observation limit, indicating that the Ga concentration is low, that is, Ga diffusion is suppressed. Has been.

(Second Embodiment)
With reference to FIG. 5, the manufacturing method of the semiconductor device of 2nd Embodiment is demonstrated. FIG. 5 is a diagram for explaining a method for manufacturing a semiconductor device, where the horizontal axis indicates time t and the vertical axis indicates substrate temperature [° C.].

  Here, an n-type Si substrate having a (111) plane as a main surface and manufactured by the FZ method and having a resistivity ρ of 6 [kΩ · cm] or more is used as the growth substrate.

  Since the process until the cleaning is completed (time t2) in the growth apparatus is the same as that in the first embodiment, the description thereof is omitted here.

After cleaning, the pressure in the growth apparatus is within a range of 6.7 × 10 ^{3 to} 2.7 × 10 ⁴ [Pa] (50 to 200 [Torr]), preferably 1.3 at time t2. The pressure is reduced to 10 ⁴ [Pa] (100 [Torr]). In the second embodiment, a hydrogen atmosphere is used in the growth chamber during decompression.

  Next, the source gas is introduced in a state where the substrate temperature is maintained at 1000 [° C.]. That is, the growth temperature is set to 1000 [° C.]. The growth temperature is usually 1200 [° C.] as the optimum temperature, but here the growth temperature is 1000 [° C.].

The flow rate of the source gas is the same as that in the first embodiment, and TMA is introduced at a flow rate of, for example, 5 [μmol / min], and ammonia (NH ₃ ) is introduced at a flow rate of, for example, 5 [SLM]. At this time, together with TMA and ammonia, a carrier gas is introduced at a flow rate of, for example, 14 [SLM]. Here, since the growth chamber has a hydrogen atmosphere, hydrogen gas is used as it is as a carrier gas.

  Although the example in which the buffer layer is an AlN layer has been described here, the present invention is not limited to this example. It is sufficient if a good GaN crystal can be formed on the buffer layer, and a nitride semiconductor layer such as AlGaN may be formed as the buffer layer.

  After forming the buffer layer, a GaN layer as a channel layer and an AlGaN layer as a barrier layer are sequentially formed. Here, when the GaN layer is formed, trimethylgallium (TMG) may be introduced as an organic metal instead of TMA. Moreover, when forming an AlGaN layer, TMA and TMG may be introduced as organic metals.

  After the growth of the buffer layer, channel layer, and barrier layer, the carrier gas is switched from hydrogen to nitrogen while introducing ammonia, and the temperature is lowered to 200 ° C. over a period of about 15 minutes from time t5 to t6. Here, when the temperature is lowered to 400 ° C., the supply of ammonia is stopped.

  After that, if an AlGaN / GaN heterostructure in which an AlGaN layer as a barrier layer is formed on a GaN layer as a channel layer, a device is created by a normal transistor manufacturing process as in the first embodiment. good.

  The relationship between the growth temperature and the sheet resistance will be described with reference to FIG. FIG. 6 is a diagram illustrating the growth temperature dependence of the sheet resistance. In FIG. 6, the horizontal axis indicates the growth temperature [° C.], and the vertical axis indicates the sheet resistance [Ω / □].

  When the growth temperature is 1200 [° C.] in a hydrogen atmosphere, the sheet resistance decreases to about 2.4 [kΩ / □]. As the growth temperature decreases, the sheet resistance increases. When the growth temperature is 1000 [° C.], the sheet resistance is 20 [kΩ / □], and the resistance value is about eight times that when the growth temperature is 1200 [° C.].

FIG. 7 shows backside SIMS analysis results when an AlN layer is grown on a high-resistance Si substrate when the growth temperature Ts is 1000 [° C.] and 1200 [° C.] in a hydrogen atmosphere. Indicates. In FIG. 7, the horizontal axis represents the depth [μm] from the AlN layer surface, and the vertical axis represents the Ga concentration [atoms / cm ³ ].

When an AlN layer is grown under conditions of a hydrogen atmosphere and a growth temperature of 1200 [° C.] (indicated by I in FIG. 7), the Ga concentration is 1 × 10 ¹⁶ [in the vicinity of the interface between the Si substrate and the AlN layer. atoms / cm ³ ] or more, and 1 × 10 ¹⁵ [atoms / cm ³ ] or more up to a depth of about 0.7 [μm].

  On the other hand, when an AlN layer is grown under the condition of a growth temperature of 1000 [° C.] (indicated by II in FIG. 7), Ga is observed near the interface of the Si substrate with the AlN layer, but other regions. Shows that it is almost below the observation limit and that Ga diffusion is suppressed.

  As described above, according to the method for manufacturing a semiconductor device of the present invention, when a Si substrate that is available at low cost and has a large substrate size is used as a growth substrate, the resistance value of the Si substrate can be increased. As a result, the parasitic capacitance can be reduced and the deterioration of the cutoff frequency characteristic can be prevented.

  In each of the above-described embodiments, the high electron mobility transistor (HEMT) has been described, but the present invention is not limited to this. The semiconductor device manufacturing method of the present invention is applied to a MESFET (Metal Semiconductor Field Effect Transistor), which is a normal Schottky gate type FET, and a junction type transistor (JFET) having a pn junction in the gate region. Applicable.

  The method for manufacturing a semiconductor device of the present invention can also be applied to the manufacture of an optical device such as a blue light emitting diode (LED) or a laser diode (LD). In the optical device, when an electrode is formed on the back substrate, an area for extracting light from the front surface is increased. Therefore, a low-resistance Si substrate is used. In this case, since the GaN is n-type, the Si substrate is also n-type. Since the p-type low resistance layer formed at the interface between Si and the semiconductor layer increases the threshold voltage of an LED or the like, the method for suppressing the generation of the p-type layer according to the present invention is effective.

It is a figure which shows the annealing temperature dependence of sheet resistance. It is a figure for demonstrating the manufacturing method of the semiconductor device of 1st Embodiment. It is a figure which shows the carrier gas dependence of sheet resistance. It is a figure (1) which shows a backside SIMS analysis result. It is a figure for demonstrating the manufacturing method of the semiconductor device of 2nd Embodiment. It is a figure which shows the growth temperature dependence of sheet resistance. It is a figure (2) which shows a backside SIMS analysis result.

Claims (7)

Introducing a silicon substrate formed by the FZ method and having a resistivity of [6 kΩ · cm] or more into the growth apparatus;
Cleaning the silicon substrate in a hydrogen atmosphere in the growth apparatus at a temperature in the range of 900 [° C.] to 1000 [° C.] ;
Making the inside of the growth apparatus an inert gas atmosphere;
Depressurizing the inside of the growth apparatus;
Raising the temperature of the silicon substrate to a growth temperature of 1100 [° C.] ;
A method of manufacturing a semiconductor device, wherein a step of introducing a source gas into the growth apparatus and forming an aluminum nitride layer as a buffer layer on the silicon substrate by metal organic vapor phase epitaxy is performed in this order . The method of manufacturing a semiconductor device according to claim 1, wherein the inert gas atmosphere is a nitrogen atmosphere. In the step of reducing the pressure in the growth apparatus,
^{3. The} method for manufacturing a semiconductor device according to claim 1, wherein the inside of the growth apparatus is set to a pressure in a range of 6.7 × 10 ^{3 to} 2.7 × 10 ⁴ [Pa]. The method of manufacturing a semiconductor device according to claim 1 or 2, characterized that you in the step of performing the cleaning, the temperature of the silicon substrate and 1000 [° C.]. Introducing a silicon substrate formed by the FZ method and having a resistivity of [6 kΩ · cm] or more into the growth apparatus;
Cleaning the silicon substrate in a hydrogen atmosphere in the growth apparatus at a temperature in the range of 900 [° C.] to 1000 [° C.] ;
Depressurizing the inside of the growth apparatus;
A step of introducing a source gas into the growth apparatus and forming an aluminum nitride layer as a buffer layer on the silicon substrate by a metal organic chemical vapor deposition method at a temperature of 1000 [° C.] in this order. A method for manufacturing a semiconductor device, comprising: In the step of reducing the pressure in the growth apparatus,
The method for manufacturing a semiconductor device according to claim 5, wherein the inside of the growth apparatus is set to a pressure in a range of 6.7 × 10 ^{3 to} 2.7 × 10 ⁴ [Pa]. In the step of performing the cleaning method of manufacturing a semiconductor device according to claim 5 or 6, characterized in that the temperature of the pre-Symbol silicon substrate and 1000 [° C.].

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