JP7347350B2 - Method for setting epitaxial growth conditions and method for manufacturing epitaxial wafers - Google Patents

Description

In the present invention, monosilane (SiH ₄ ) gas diluted with hydrogen (H ₂ ) is introduced into a reaction vessel, and single crystal silicon is epitaxially grown on a growth substrate made of a group IV element including silicon under reduced pressure. The present invention relates to a method of setting epitaxial growth conditions and a method of manufacturing an epitaxial wafer.

There are two crystal growth methods for producing silicon single crystals: the Czochralski method (hereinafter referred to as the CZ method) and the floating zone method (hereinafter referred to as the FZ method), and the single crystals formed by each method are cut out and polished. Therefore, it is used as a silicon substrate (wafer). However, point defects and oxygen are introduced during the crystal growth process, which affect the electrical characteristics of semiconductor devices. Epitaxial wafers with single crystal silicon layers are also used.

There are two types of epitaxial growth equipment: normal pressure type and reduced pressure type, and the normal pressure type is generally used because of its high productivity. In atmospheric pressure equipment, film formation is mainly performed at around 1100°C using trichlorosilane, but autodoping occurs, where dopants from the substrate diffuse outward during film formation and are incorporated into the film formation layer, which can cause problems. There is. As a method to solve this problem, a reduced pressure type device that can form a film at a low temperature is used. Generally, films are formed using dichlorosilane or monosilane at about 1000° C., but methods for forming films at lower temperatures are described in Patent Documents 1 to 4.

Patent Document 1 discloses that a substrate is placed in a reaction vessel whose base pressure is set to 1×10 ⁻⁸ Torr (1.3×10 ⁻⁶ Pa) or less, and the temperature inside the reaction vessel is set to 500° C. or more and 800° C. A method is described in which the film is formed with the pressure in the reaction container being several hundred milliTorr or less. Patent Document 2 describes a method of forming a film at 600° C. or higher using a mixed gas of silane, fluorosilane, and hydrogen. Patent Document 3 describes a method of forming a film using monosilane gas at a temperature of 550° C. or higher and lower than 750° C. Patent Document 4 describes a method of heating a single-crystal silicon thin film at a temperature below 350° C. and then raising the temperature to 350 to 530° C. and forming a film using a silicon source gas and a carrier gas that does not contain oxygen. .

Japanese Unexamined Patent Publication No. 63-70515 Japanese Patent Application Publication No. 1-11321 Japanese Patent Application Publication No. 2003-309070 JP2006-080486A

The film forming method described in Patent Document 1 is performed in a high vacuum environment, and in order to maintain the base pressure below 1 × 10 ^-8 Torr (1.3 × 10 ^-6 Pa), it is difficult to maintain. There was a problem in that an ultra-high vacuum device was required. The film forming method described in Patent Document 2 has a problem in that it requires fluorosilane, which is not common. In the film forming method described in Patent Document 3, the pressure inside the reaction vessel is 1 mTorr (0.13 Pa), and as in Patent Document 1, a high vacuum device is required. In the film forming method described in Patent Document 4, the temperature at which the substrate is introduced into the reaction vessel is lower than the growth temperature in order to suppress oxidation due to trace amounts of oxygen contained in nitrogen in the carrier gas. It is necessary to raise the temperature after charging the reactor into the reaction vessel, which poses a problem of poor productivity.

As described above, there are various problems in the epitaxial growth of single crystal silicon at low temperatures that has been proposed in the past, and it is possible to use common raw material gases such as monosilane and hydrogen gas without reducing productivity. It is required to form a film using a general-purpose decompression device that does not require high vacuum. However, with regard to the epitaxial growth of single crystal silicon using common source gases, there has been no detailed study of the growth conditions, including those in low-vacuum regions, and the conditions must be determined through trial and error. There was a problem of a significant drop in productivity.

The present invention has been made to solve the above problems, and when manufacturing single-crystal silicon epitaxial wafers at low temperatures, it is possible to easily and quickly set epitaxial growth conditions, and when a general-purpose decompression device is used. It is an object of the present invention to provide a method for setting epitaxial growth conditions that enables epitaxial growth with high productivity even when the method is used, and a method for manufacturing an epitaxial wafer in which epitaxial growth is performed using the epitaxial growth conditions set by the setting method.

The present invention has been made to achieve the above object, and monosilane (SiH ₄ ) gas diluted with hydrogen (H ₂ ) is introduced into a reaction vessel to react with silicon-containing group IV gas under reduced pressure. A method of setting epitaxial growth conditions when epitaxially growing single-crystal silicon on a growth substrate made of the above-mentioned elements, wherein the epitaxial growth conditions include at least a growth temperature T (unit: °C) and a partial pressure P of monosilane gas in a reaction vessel. (unit: Pa), the growth temperature T is selected from a range of 500°C or more and 800°C or less, and the partial pressure P of the monosilane gas in the reaction vessel and the growth temperature T are
P<0.0017exp(10500/(T+273.15))
A method for setting epitaxial growth conditions is provided, in which the epitaxial growth conditions are set by selecting conditions that satisfy the following relationship.

According to such a method of setting epitaxial growth conditions, when manufacturing single-crystal silicon epitaxial wafers at low temperatures, epitaxial growth conditions can be easily and quickly set over a wide pressure range including a region with a low degree of vacuum.

At this time, the epitaxial growth conditions further include the flow rate ratio of the monosilane gas and the hydrogen (SiH ₄ flow rate/H ₂ flow rate), and the flow rate ratio of the monosilane gas and the hydrogen (SiH ₄ flow rate/H ₂ flow rate) is set to 1. The epitaxial growth conditions can be set by selecting from a range of .2×10 ⁻² or more and 1.0 or less.

This makes it possible to form a film more stably and to set a flow rate ratio that can more stably suppress the formation of defects.

At this time, the epitaxial growth conditions further include the pressure within the reaction vessel, and the pressure within the reaction vessel is selected from a range of 1.33 x 10 ² Pa or more and 1.33 x 10 ⁴ Pa or less. This can be a method of setting epitaxial growth conditions.

This makes it possible to set a pressure range in which the film formation rate is sufficiently high and stable, and the formation of defects can be more stably suppressed.

At this time, the epitaxial growth conditions further include a silicon isotope composition of the monosilane gas, and a monosilane gas having a composition in which the content of ²⁸ Si in silicon in the monosilane gas is 99.9% or more is selected as the monosilane gas. This can be a method of setting epitaxial growth conditions.

This makes it possible to set growth conditions for manufacturing an epitaxial wafer suitable as a substrate for a quantum computer.

At this time, monosilane gas diluted with hydrogen is introduced into a reaction vessel, and single crystal silicon is epitaxially grown on a growth substrate made of a group IV element including silicon under reduced pressure, the method comprising: It is possible to provide an epitaxial wafer manufacturing method in which epitaxial growth is performed using epitaxial growth conditions set by the method for setting epitaxial growth conditions described above.

According to such an epitaxial wafer manufacturing method, it is possible to easily, quickly, and stably grow single crystal silicon epitaxially over a wide pressure range and at low temperatures without the need for trial and error, thereby increasing productivity. improves.

At this time, the epitaxial wafer manufacturing method may use a single crystal silicon substrate as the growth substrate.

Thereby, the versatility of the obtained epitaxial wafer can be increased.

At this time, the method for producing an epitaxial wafer may use, as the growth substrate, a substrate in which an epitaxial layer is formed on a single crystal silicon substrate.

Thereby, the degree of freedom of the obtained epitaxial wafer can be increased.

At this time, before performing the epitaxial growth, the growth substrate is heat-treated in a hydrogen atmosphere at a temperature of 600° C. or more and 800° C. or less for a period of 1 minute or more and 60 minutes or less, so that the surface of the growth substrate is The present invention can be used as an epitaxial wafer manufacturing method for removing a natural oxide film.

If the natural oxide film is removed in this way, the natural oxide film can be removed more effectively.

At this time, before performing the epitaxial growth, the growth substrate may be subjected to plasma treatment using plasma containing hydrogen to remove a natural oxide film on the surface of the growth substrate.

By removing the natural oxide film in this manner, the natural oxide film can also be removed more effectively. Further, it is not necessary to perform heating, and furthermore, it can be performed in a separate processing apparatus in parallel with epitaxial growth, further improving productivity.

As described above, according to the method for setting epitaxial growth conditions of the present invention, when producing single-crystal silicon epitaxial wafers at low temperatures, it is possible to It becomes possible to easily and quickly set epitaxial growth conditions, and as a result, productivity can be improved.

1 is a diagram showing a flow of a method for manufacturing an epitaxial wafer according to the present invention. FIG. 2 is a diagram showing the relationship between growth temperature T, monosilane partial pressure P, and crystallinity. 2 is a transmission electron microscope image of a cross section of an epitaxial wafer in an example and a comparative example.

Hereinafter, the present invention will be explained in detail, but the present invention is not limited thereto.

As mentioned above, when manufacturing single-crystal silicon epitaxial wafers at low temperatures, epitaxial growth conditions can be easily and quickly set, and epitaxial growth with high productivity can be achieved even when using a general-purpose decompression device. There was a need for a method for setting epitaxial growth conditions.

As a result of intensive studies on the above-mentioned problem, the present inventors introduced monosilane (SiH ₄ ) gas diluted with hydrogen (H ₂ ) into the reaction vessel, and under reduced pressure reacted with group IV elements including silicon. A method of setting epitaxial growth conditions when epitaxially growing single crystal silicon on a growth substrate made of unit: Pa), the growth temperature T is selected from a range of 500°C or more and 800°C or less, and the partial pressure P of the monosilane gas in the reaction vessel and the growth temperature T are
P<0.0017exp(10500/(T+273.15))
The epitaxial growth conditions are set by selecting conditions that satisfy the following relationship. When manufacturing single-crystal silicon epitaxial wafers at low temperatures, the pressure range includes low vacuum regions that do not require ultra-high vacuum. However, the present invention has been completed based on the discovery that epitaxial growth conditions can be easily and quickly set.

Hereinafter, a method for manufacturing an epitaxial wafer according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 shows a manufacturing flow of an epitaxial wafer according to the present invention. In the step S10 of FIG. 1, epitaxial growth conditions are set. The step S11 in FIG. 1 is a step of preparing a wafer made of a group IV element including silicon as a growth substrate. S12 in FIG. 1 is a step of epitaxially growing single crystal silicon. In addition, although the process flow in the order of S10, S11, and S12 is described in FIG. 1, setting of epitaxial growth conditions (S10) may be performed before performing epitaxial growth (S12), and in particular The order is not limited. Each step will be explained in detail below.

[Setting epitaxial growth conditions]
First, a method of setting epitaxial growth conditions in the step S10 in FIG. 1 will be described.

In the epitaxial growth according to the present invention, monosilane (SiH ₄ ) gas diluted with hydrogen (H ₂ ) is used as a source gas. By using hydrogen as a diluent gas, a high vacuum environment is not required, and film formation can be performed in a low vacuum environment. There are two possible reasons for this.

The first is to suppress excessive decomposition of monosilane. When pressure is high, monosilanes collide with each other, forming microscopic silicon that causes defects and the formation of polycrystalline silicon.Hydrogen suppresses the decomposition of monosilane, thereby suppressing the formation of microscopic silicon. I can do it. For this reason, it becomes possible to form a film in a low vacuum environment without requiring a high vacuum environment where the frequency of molecular collisions is low.

The second is to suppress the generation of SiO _x (x: a number from 1 to 2). Since oxygen contained in the gas used for epitaxial growth cannot be completely eliminated, the source gas contains a trace amount of oxygen. In addition, when the reaction vessel is opened for maintenance of the film deposition equipment, oxygen and moisture adhere to the inside of the reaction vessel, and these gradually desorb from the reaction vessel during film formation, resulting in oxygen being mixed in during film formation. There is. When an inert atmosphere (nitrogen, helium, neon, argon, etc.) is used as a carrier gas, oxygen and monosilane react to generate SiO _x which becomes the nucleus of defects, which poses a problem. On the other hand, when hydrogen is used as the carrier gas, oxygen and hydrogen react and are exhausted as water, so it is possible to suppress the generation of SiO _x .

Further, one of the reasons why the growth temperature T is set within the range of 500° C. or more and 800° C. or less is to enable formation of a single crystal silicon film with suppressed autodoping. Furthermore, since diffusion of atoms can be suppressed, it is also effective when forming a δ-doped layer. A δ-doped layer is a layer in which an element different from that of the base material is introduced to the extent of a monoatomic layer. For example, this applies to the case where less than a monoatomic layer (1.36×10 ¹⁵ atoms/cm ² ) of oxygen or carbon is introduced onto a silicon substrate.

Since the higher the growth temperature, the higher the epitaxial growth rate, a thick epitaxial layer can be formed in a short time by forming a film at a high temperature. On the other hand, if a thin epitaxial layer is desired to be formed, the film may be formed at a low temperature. In this way, the growth temperature can be changed depending on the desired thickness of the epitaxial layer. Furthermore, when the substrate contains Ge and Sn, which have low heat resistance, it is desirable to form the film at a low temperature to prevent the crystallinity from deteriorating.

FIG. 2 shows the results of an investigation by the present inventors on the relationship between the crystallinity of the epitaxial layer. The present inventors have conducted extensive research on the epitaxial growth conditions for epitaxially growing single crystal silicon on a growth substrate made of group IV elements including silicon under reduced pressure by introducing monosilane gas diluted with hydrogen into a reaction vessel. The investigation revealed that the relationship between the partial pressure P (Pa) of monosilane gas during epitaxial growth and the growth temperature T (°C) is as shown in Figure 2.
P<0.0017exp(10500/(T+273.15))
It was revealed that it is possible to form an epitaxial layer of single crystal silicon when the following conditions are satisfied. Such conditions are particularly effective in the case of growth using a general-purpose decompression device with a low degree of vacuum, which has not been studied in the past.As long as the above conditions are met, the growth temperature T and monosilane partial pressure P can be set arbitrarily, making it easy to set conditions according to the purpose. However, the conditions of the growth temperature T and monosilane partial pressure P described above are also applicable to growth under a conventional high vacuum.

Under conditions that satisfy the above formula, molecules attached to the surface can sufficiently diffuse on the surface, so that single crystal silicon can be formed. On the other hand, if the above conditions are not met, amorphous silicon or polysilicon is formed. This occurs because the attached molecules do not diffuse sufficiently. At low temperatures, it becomes amorphous silicon, and at high temperatures, it becomes polysilicon. At this time, the attached molecules may be SiH ₃ or SiH ₂ in which hydrogen is dissociated from monosilane.

Therefore, if epitaxial growth conditions are set by selecting conditions for monosilane gas partial pressure P and growth temperature T that satisfy the above relational expression, even if epitaxial growth is performed at a higher pressure (lower degree of vacuum) than before, Conditions that enable epitaxial growth of single crystal silicon can be set simply and quickly without the need for trial and error.

The flow rate ratio of monosilane gas and hydrogen (SiH ₄ flow rate/H ₂ flow rate) can also be set as the epitaxial growth condition. At this time, it is preferable to select the flow rate ratio of monosilane gas and hydrogen (SiH ₄ flow rate/H ₂ flow rate) from a range of 1.2×10 ⁻² or more and 1.0 or less. By setting such a flow rate ratio, epitaxial growth can be performed more stably at a sufficient film formation rate without generating defects. If the flow rate ratio is 1.2×10 ⁻² or more, the dissociation of monosilane is further promoted and stable film formation becomes possible. On the other hand, if the flow rate ratio is 1.0 or less, the amount of hydrogen is sufficient, so that the gas phase reaction of monosilane can be effectively suppressed, and the formation of defects can be suppressed more stably.

The pressure inside the reaction vessel can also be set as the epitaxial growth condition. At this time, it is preferable to select the pressure inside the reaction vessel from a range of 1.33×10 ² Pa or more and 1.33×10 ⁴ Pa or less. With such a pressure range, the film formation rate is sufficiently high and stable, and the formation of defects can be suppressed more stably.

The composition of silicon isotope in monosilane gas can also be set as the epitaxial growth conditions. At this time, it is preferable to select, as the monosilane gas, a monosilane gas having a composition in which the content of ²⁸ Si relative to silicon in the monosilane gas is 99.9% or more. There are three stable isotopes of silicon: ²⁸ Si, ²⁹ Si, and ³⁰ Si, and their natural abundance ratios are 92.23%, 4.67%, and 3.1%, but the content of ²⁸ Si By forming a ²⁸ Si epitaxial layer using a monosilane gas having a concentration of 99.9% or more, the following two effects can be obtained.

The first is an improvement in thermal conductivity. In a silicon epitaxial wafer with a natural abundance ratio, ²⁹ Si and ³⁰ Si serve as phonon scattering sources and deteriorate thermal conductivity, so by using only ²⁸ Si, thermal conductivity can be improved. If heat generated in a device can be easily dissipated from the device region by improving thermal conductivity, device characteristics can be improved.

The second reason is that the influence of nuclear spin can be eliminated. In quantum computing, eliminating the influence of disturbances (heat, electric fields, magnetic fields, etc.) is important for stable operation. ²⁸ Si and ³⁰ Si do not have nuclear spin, but ²⁹ Si has nuclear spin, so when a quantum bit, which is the basic element of a quantum computer, is formed on a silicon epitaxial wafer containing ²⁹ Si, There is a problem in that the time it takes for a quantum state to be destroyed (decoherence time) becomes shorter due to the influence of nuclear spin. Therefore, by using a wafer including an epitaxial layer made using a monosilane gas containing almost no ²⁹ Si and having a ²⁸ Si content of 99.9% or more, stable quantum computing becomes possible. Examples of quantum bits formed on silicon epitaxial wafers include superconducting quantum bits and quantum bits using semiconductor electrons.

Note that such monosilane gas can be produced, for example, by centrifuging monosilane gas having a natural Si isotope composition.

[Manufacture of epitaxial wafers]
Next, manufacturing of epitaxial wafers will be explained. After epitaxial growth conditions are set as described above, epitaxial wafers are manufactured.

(growth substrate)
First, the growth substrate (S11 in FIG. 1) will be explained. In the epitaxial wafer manufacturing method according to the present invention, the growth substrate is not particularly limited as long as it is a wafer made of a group IV element including silicon. For example, single crystal silicon, SiGe, or SiGeC can be used.

Here, the method for manufacturing the growth substrate is not particularly limited. A substrate manufactured by the CZ method or a substrate manufactured by the FZ method may be used.

In particular, it is preferable to use a single crystal silicon substrate as the substrate made of a group IV element containing silicon. Use of a single crystal silicon substrate increases versatility. At this time, a substrate subjected to ion implantation and heat treatment may be used as the silicon substrate.

Further, as the substrate made of a group IV element containing silicon, it is also preferable to use a substrate in which an epitaxial layer is formed on a single crystal silicon substrate. The use of such a growth substrate increases the degree of freedom. For example, a substrate in which a single crystal silicon epitaxial layer is formed on a single crystal silicon substrate manufactured by the CZ method or the FZ method may be used.

Furthermore, it is also preferable to use a substrate in which a single crystal SiGe layer is formed on a single crystal silicon substrate. Since the epitaxial wafer manufacturing method according to the present invention is a method of epitaxial growth at a low temperature (500 to 800° C.), it is particularly effective when forming silicon on SiGe, which has such low heat resistance. A structure in which SiGe and silicon are sequentially formed on a silicon substrate can be used as a quantum well. For example, since such a quantum well can confine carriers in the SiGe layer, it can be operated as a quantum bit by externally manipulating the spin of electrons confined in the SiGe layer.

Furthermore, a superlattice in which single-crystal SiGe layers and single-crystal silicon epitaxial layers are alternately formed on a single-crystal silicon substrate can be fabricated. This is particularly effective when forming a gate all-around FET (Field Effect Transistor). In a horizontal gate all-around FET, a channel made of silicon can be formed by creating a superlattice of silicon and SiGe and then removing the SiGe layer by etching. In particular, by low-temperature epitaxial growth of single crystal silicon on a substrate on which a SiGe layer is formed, it is possible to prevent Ge in the SiGe layer from diffusing into the Si layer.

(Epitaxial growth method)
Next, the step of epitaxially growing single crystal silicon in S12 of FIG. 1 will be described.

The epitaxial growth apparatus used for epitaxial growth is not particularly limited as long as it can reduce pressure and heat to a predetermined temperature, and a batch type or single wafer type may be used.

The temperature at which the growth substrate is transferred into the reaction container is preferably the same as the growth temperature. By doing so, there is no time to raise or lower the temperature in the reaction container after transferring the growth substrate, improving productivity. Further, in the epitaxial growth method according to the present invention, the growth temperature is 500 to 800° C., and the temperature inside the reaction vessel is low, so no slip occurs on the growth substrate.

(Removal of natural oxide film)
If a natural oxide film exists on the surface of the growth substrate, it is preferable to first perform a pretreatment to remove the natural oxide film. Although there is no particular limitation as long as the natural oxide film can be removed, for example, heat treatment may be performed in a hydrogen atmosphere at a temperature of 600° C. or more and 800° C. or less for 1 minute or more and 60 minutes or less before epitaxial growth. By removing the natural oxide film under such conditions, defects can be prevented from occurring. Note that it is more effective to remove the natural oxide film by cleaning with hydrofluoric acid or the like before processing in a hydrogen atmosphere (before introducing the growth substrate into the growth apparatus).

Furthermore, in order to remove a native oxide film on the surface of the growth substrate, it is also preferable to perform plasma treatment using plasma containing hydrogen before epitaxial growth. In this case, the natural oxide film can be removed at a lower temperature than when the natural oxide film is removed by heating in an atmosphere containing hydrogen. Therefore, it is particularly effective when the growth substrate contains Ge and Sn, which have low heat resistance. For example, in the case of SiGe, the higher the Ge ratio, the lower the allowable temperature limit. Note that when removing the natural oxide film by using plasma containing hydrogen, the natural oxide film may be removed while the substrate temperature is at room temperature, or the natural oxide film may be removed by heating. . The natural oxide film can also be removed more effectively by this natural oxide film removal method. Furthermore, it can be performed in a separate processing device in parallel with epitaxial growth, further improving productivity. At this time, for example, when epitaxial growth is performed successively, such as epitaxially growing SiGe and then epitaxially growing Si, a natural oxide film is not formed, so there is no need to perform a process for removing the natural oxide film.

(epitaxial growth)
After performing the above pretreatment as necessary, monosilane gas diluted with hydrogen is introduced using the growth conditions set as described above to perform epitaxial growth of single crystal silicon on the growth substrate.

Doping gas may be introduced during epitaxial growth. For example, diborane can be used when doping boron, and phosphine can be used when doping phosphorus.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to examples, but the present invention is not limited thereto.

First, growth substrates used in Examples and Comparative Examples described below were prepared. The prepared growth substrate was a single crystal silicon substrate, and its conductivity type, diameter, and crystal plane orientation were as follows.
Substrate conductivity type: p type Diameter: 300mm
Crystal plane orientation: (100)

Separately, conditions for epitaxial growth of single crystal Si were set. The raw material gases are monosilane and hydrogen as a carrier gas (diluent gas). As the growth temperature T (°C), T=600, 650, 700, and 750°C were selected from the range of 525 to 750°C. Monosilane partial pressure P is selected from the range of 22 to 199 Pa, P = 22, 66, 199 Pa,
P<0.0017exp(10500/(T+273.15))
Examples and comparative examples were determined depending on whether the conditions were satisfied or not. Specifically, it is as follows.

(Example)
T=600℃, P=22,66,199Pa,
T=650℃, P=22,66Pa,
T=700℃, P=22,66Pa,
T=750℃, P=22Pa,
These are each condition.

(Comparative example)
T=650℃, P=199Pa,
T=700℃, P=199Pa,
T=750℃, P=66,199Pa,
These are each condition.

In addition, in both Examples and Comparative Examples, the SiH ₄ flow rate/H ₂ flow rate ratio was set to 0.04. The film formation time was varied depending on the temperature and monosilane partial pressure.

Next, the prepared single crystal silicon substrate was cleaned with HF, then carried into a reaction apparatus, and subjected to hydrogen baking to remove the natural oxide film. The temperature at this time was 800°C and the time was 15 minutes.

Thereafter, epitaxial growth of single crystal Si was performed according to the set growth conditions. As a result of evaluating the epitaxial layer thickness obtained by epitaxial growth using a capacitive film thickness measuring device, it was found that an epitaxial layer with a thickness of 70 to 1700 nm was formed, although the epitaxial layer thickness varies depending on the growth temperature and monosilane partial pressure. I confirmed that

Further, in order to evaluate crystallinity, cross-sectional TEM (Transmission Electron Microscopy) observation was performed. Figure 3 shows the observation results. The growth temperature T (unit: °C) and the partial pressure P (unit: Pa) of monosilane gas in the reaction vessel are
P<0.0017exp(10500/(T+273.15))
It can be seen that a polysilicon layer is formed in the comparative example that does not satisfy the above relationship, but single crystal silicon is formed under the conditions of the example that satisfies the above relationship.

Note that the present invention is not limited to the above embodiments. The above-mentioned embodiments are illustrative, and any embodiment that has substantially the same configuration as the technical idea stated in the claims of the present invention and has similar effects is the present invention. covered within the technical scope of.

Claims (6)

Epitaxial growth when monosilane (SiH ₄ ) gas diluted with hydrogen (H ₂ ) is introduced into a reaction vessel to epitaxially grow single crystal silicon on a growth substrate made of group IV elements including silicon under reduced pressure. A method of setting conditions,
The growth substrate is a single crystal silicon substrate,
The epitaxial growth conditions include at least the growth temperature T (unit: °C), the partial pressure P (unit: Pa) of the monosilane gas in the reaction vessel , and the flow rate ratio of the monosilane gas and the hydrogen (SiH ₄ flow rate/H ₂ flow rate). including,
The growth temperature T is selected from a range of 500° C. or higher and 800° C. or lower, and
The partial pressure P of the monosilane gas in the reaction vessel and the growth temperature T are
P<0.0017exp(10500/(T+273.15))
Select the conditions that satisfy the relationship ,
Further, the epitaxial growth conditions are set by selecting a flow rate ratio of the monosilane gas and the hydrogen (SiH ₄ flow rate/H ₂ flow rate) from a range of 1.2×10 ⁻² or more and 1.0 or less. How to set epitaxial growth conditions. The epitaxial growth conditions further include a pressure within the reaction vessel,
2. The method for setting epitaxial growth conditions according to claim 1 , wherein the pressure in the reaction vessel is selected from a range of 1.33×10 ² Pa or more and 1.33×10 ⁴ Pa or less. The epitaxial growth conditions further include a silicon isotope composition of the monosilane gas,
3. The method for setting epitaxial growth conditions according to claim 1 , wherein a monosilane gas having a composition in which the content of ²⁸ Si in silicon in the monosilane gas is 99.9% or more is selected as the monosilane gas. A method for producing an epitaxial wafer in which monosilane gas diluted with hydrogen is introduced into a reaction vessel and single crystal silicon is epitaxially grown on a growth substrate made of a group IV element including silicon under reduced pressure, the method comprising:
Using a single crystal silicon substrate as the growth substrate,
A method for manufacturing an epitaxial wafer, comprising performing epitaxial growth using epitaxial growth conditions set by the method for setting epitaxial growth conditions according to any one of claims 1 to 3 . Before performing the epitaxial growth, the growth substrate is heat-treated in a hydrogen atmosphere at a temperature of 600° C. or more and 800° C. or less for a period of 1 minute or more and 60 minutes or less, thereby reducing the natural oxidation of the surface of the growth substrate. 5. The method for manufacturing an epitaxial wafer according to claim 4 , further comprising removing the film. 6. The epitaxial method according to claim 4, wherein, before performing the epitaxial growth, the growth substrate is subjected to plasma treatment using plasma containing hydrogen to remove a natural oxide film on the surface of the growth substrate. Wafer manufacturing method.

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