Method for manufacturing an epitaxial wafer

Abstract

The present application provides a method for manufacturing an epitaxial wafer, which is a method for manufacturing an epitaxial wafer in which a single crystal silicon layer is formed on a wafer composed of a group IV element including silicon, the method comprising: a step of removing a natural oxide film from a surface of the wafer composed of a group IV element including silicon in a hydrogen-containing atmosphere; a step of oxidizing the wafer after the natural oxide film is removed, thereby forming an oxygen atom layer; and a step of epitaxially growing a single crystal silicon on the surface of the wafer after the oxygen atom layer is formed, and in the method, a planar concentration of oxygen of the oxygen atom layer is set to 4 x 10 14 atoms / cm 2 or less. Thus, a method for manufacturing an epitaxial wafer in which an oxygen atom layer can be stably and easily introduced into an epitaxial layer and an epitaxial layer having high-quality single crystal silicon can be provided.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for manufacturing an epitaxial wafer and an epitaxial wafer. BACKGROUND

[0002] For a silicon substrate that forms a semiconductor element such as a solid-state imaging element or other transistor, it is required to have a function of gettering an element such as a heavy metal that deteriorates or degrades the characteristics of the element. As for gettering, various methods such as providing a polysilicon (Poly-Si) layer on the back surface of a silicon substrate, forming a layer with damage by sandblasting processing, using a silicon substrate with high concentration of boron, or forming a deposit have been proposed and put into practical use. Gettering by oxygen deposition removes a metal that has a large tendency to ionize (small electronegativity) with respect to oxygen that has a large electronegativity by absorbing it.

[0003] Further, a method of forming a gettering layer, so-called "proximity gettering", in the vicinity of an active region of an element has been proposed. For example, a substrate formed by epitaxial growth of silicon on a substrate in which carbon ions have been implanted. The "gettering" must diffuse an element to a gettering site (by causing the metal to bind or cluster at the site more than to exist as a single element, thereby reducing the energy of the entire system), and the diffusion coefficient of a metal element contained in silicon differs depending on the element. Further, considering that the metal cannot diffuse to the gettering site due to process low-temperature in recent years, a method of proximity gettering has been proposed.

[0004] If oxygen can be used for proximity gettering, it can become a silicon substrate with a very powerful gettering layer. In particular, if it is an epitaxial wafer with an oxygen atom layer in the middle of the epitaxial layer, even in the low-temperature process in recent years, metal impurities can be reliably removed.

[0005] Above, mainly the use of oxygen for proximity gettering to remove metal impurities has been described. As other effects of oxygen, for example, an effect of preventing auto-doping at the time of epitaxial growth by forming a CVD oxide film on the back surface is known.

[0006] Next, the prior art will be described. Patent Document 1 describes a method of forming a thin layer of oxygen on silicon and further growing silicon. This method is a technology based on ALD ("atomic layer deposition"). ALD is a method of adsorbing a molecule containing a target atom, and then causing unnecessary atoms (molecules) in the molecule to deviate and separate, which utilizes surface binding, is extremely precise and has good reaction control, and is widely used.

[0007] Patent Literature 2 describes a method of adsorbing and depositing an oxide film or other substance after forming a natural oxide film on a clean surface of silicon formed by vacuum heating or the like.

[0008] Patent Literatures 3 and 4 show that device characteristics can be improved (mobility can be increased) by introducing a plurality of layers of oxygen atoms on a silicon substrate.

[0009] Patent Literature 5 shows a method of forming an epitaxial layer on an atomic layer having a thickness of 5 nm or less using SiH4 gas. Also, a method of providing the atomic layer as an oxygen atom layer and forming the oxygen atom layer using oxygen gas is shown.

[0010] Patent Literatures 6 and 7 describe a method of epitaxially growing single-crystal silicon after forming an oxide film by bringing the surface of a semiconductor substrate into contact with an oxidizing gas or an oxidizing solution.

[0011] Patent Literature 6 describes that a natural oxide film is removed by cleaning with dilute hydrofluoric acid. In addition, Patent Literature 6 describes a method of flowing a silicon film formation gas after flowing an oxidizing gas.

[0012] Non-Patent Literature 1 shows a method of forming an epitaxial layer of single-crystal silicon by performing oxidation in the atmosphere after removing a natural oxide film with HF, then forming an amorphous silicon film by reduced pressure CVD, and then performing crystallization heat treatment.

[0013] Prior Art Documents

[0014] Patent Literature

[0015] Patent Literature 1: Japanese Patent Application Publication No. 2014-165494

[0016] Patent Literature 2: Japanese Patent Application Publication No. H05-243266

[0017] Patent Literature 3: U.S. Patent No. 7,153,763

[0018] Patent Literature 4: U.S. Patent No. 7,265,002

[0019] Patent Literature 5: Japanese Patent Application Publication No. 2019-004050

[0020] Patent Literature 6: Japanese Patent Application Publication No. 2008-263025

[0021] Patent Literature 7: Japanese Patent Application Publication No. 2009-016637

[0022] Non-Patent Literature

[0023] Non-Patent Literature 1: I. Mizushima et al., Jpn. J. Appl. Phys. 39 (2000) 2147. SUMMARY

[0024] Technical Problem to be Solved by the Invention

[0025] As described above, a method of removing metal impurities by forming an oxygen layer in a wafer has been used in the past. However, in the prior art, although a thin layer of oxygen can be obtained with high precision, there are problems such as complicated device configuration or an increased number of processes.

[0026] For example, in the technology described in Patent Literature 1, since epitaxial growth of single crystal silicon cannot be performed by ALD, at least two chambers of ALD and CVD are necessary, and there is a problem of complicated device configuration. Further, since oxidation is performed by ozone, there is a problem of necessity of a special generator for generating ozone.

[0027] Further, in the technology described in Patent Literature 5, in order to prevent SiH4 from reacting with oxygen and causing explosion, there is a problem of necessity of two chambers separated by an exhaust system.

[0028] Further, with respect to the technology described in Patent Literature 6, the inventors of the present application have found that there is a problem that since natural oxide film cannot be sufficiently removed or oxidation occurs immediately after the removal of the natural oxide film at the time of cleaning with dilute hydrofluoric acid, it is difficult to stably perform epitaxial growth of single crystal silicon. Further, in order to prevent oxidizing gas from reacting with a silicon deposition gas and causing explosion, a special device considering safety is necessary.

[0029] In the method described in Non-Patent Literature 1, heat treatment must be performed at the time of crystallization, and there is a problem of an increased number of processes. Further, since amorphous silicon generally contains a large amount of hydrogen, defects caused by hydrogen can be formed at the time of crystallization heat treatment.

[0030] Further, in the prior art, there is a problem that there is no description of a method for stably introducing an oxygen layer or a specific description of a method for forming an epitaxial layer of high-quality single crystal silicon.

[0031] For example, in Patent Literature 2, there is no description of a method of forming an epitaxial layer of single crystal silicon on a wafer surface without generating dislocations and stacking faults.

[0032] Further, specific growth methods of a silicon wafer in which a plurality of oxygen atom layers are introduced are not mentioned in Patent Literatures 3 and 4.

[0033] Further, in Patent Literatures 6 and 7, there is no description of a method of removing a natural oxide film before contact with an oxidizing gas or an oxidizing solution.

[0034] As described above, for the prior art, although a thin layer of oxygen can be obtained with high precision, there are problems such as complicated device configuration, unstable introduction of the layer of oxygen, and inability to obtain an epitaxial layer of high-quality single crystal silicon. Therefore, there is a demand for a manufacturing method of an epitaxial wafer capable of stably and simply introducing a layer of oxygen atoms to an epitaxial layer.

[0035] In view of the above problems of the prior art, the present application aims to provide a manufacturing method of an epitaxial wafer capable of stably and simply introducing a layer of oxygen atoms to an epitaxial layer and having an epitaxial layer of high-quality single crystal silicon, and an epitaxial wafer.

[0036] Technical means for solving the technical problem

[0037] The present application is achieved in order to achieve the above object, and provides a manufacturing method of an epitaxial wafer, which is a manufacturing method of an epitaxial wafer in which a single crystal silicon layer is formed on a wafer composed of a Group IV element including silicon, and which includes: a step of removing a natural oxide film from a surface of the wafer composed of a Group IV element including silicon in a hydrogen-containing atmosphere; a step of oxidizing the wafer after the natural oxide film is removed, thereby forming a layer of oxygen atoms; and a step of epitaxially growing single crystal silicon on the surface of the wafer after the layer of oxygen atoms is formed, and in the manufacturing method, a planar concentration of oxygen of the layer of oxygen atoms is set to 4 x 10 14 atoms / cm 2 and the like.

[0038] According to the above manufacturing method of an epitaxial wafer, dislocations and stacking faults are not formed on the layer of oxygen atoms, and single crystal silicon can be simply grown on the wafer.

[0039] At this time, as the wafer composed of a Group IV element including silicon, a single crystal silicon wafer is preferably used.

[0040] According to the above manufacturing method of an epitaxial wafer, the versatility is high.

[0041] At this time, it is preferable that, in the step of removing the natural oxide film, the natural oxide film is removed by heating the wafer in a hydrogen-containing atmosphere.

[0042] If the natural oxide film is removed in the above manner, the natural oxide film can be more effectively removed.

[0043] At this time, it is preferable that, in the step of removing the natural oxide film, the natural oxide film is removed by heating the wafer to a temperature of 800°C or higher and 1250°C or lower and maintaining the temperature in the range for 1 second or longer and 5 minutes or shorter.

[0044] By setting the temperature range and the time in the step of removing the natural oxide film, the natural oxide film can be more stably removed.

[0045] At this time, it is preferable that the natural oxide film be removed by using a plasma containing hydrogen in the process of removing the natural oxide film.

[0046] If the natural oxide film is removed in the above-described manner, the natural oxide film can be removed more effectively.

[0047] At this time, it is preferable that the wafer be oxidized in an oxygen-containing atmosphere in the process of forming the oxygen atom layer.

[0048] By setting the above-described environment in the process of forming the oxygen atom layer, the wafer can be oxidized more simply without the need to prepare a special apparatus.

[0049] At this time, it is preferable that the wafer be oxidized in the atmosphere in the process of forming the oxygen atom layer.

[0050] By setting the above-described environment in the process of forming the oxygen atom layer, the wafer can be oxidized more simply without the need to prepare a special apparatus.

[0051] At this time, it is preferable that the epitaxial growth of the single crystal silicon be performed at a temperature of 450°C or higher and 800°C or lower in the process of performing the epitaxial growth of the single crystal silicon.

[0052] By setting the above-described temperature range in the process of performing the epitaxial growth of the single crystal silicon, the epitaxial growth can be performed more stably and without defects.

[0053] At this time, it is preferable that the process of forming the oxygen atom layer by oxidizing the wafer and the process of performing the epitaxial growth of the single crystal silicon be alternately performed a plurality of times.

[0054] By providing the oxygen atom layer in multiple layers in the above-described manner, the gettering effect can be further improved compared to the case where the oxygen atom layer is one layer.

[0055] Further, the present application provides an epitaxial wafer which is an epitaxial wafer having a single crystal silicon layer on a wafer composed of a Group IV element containing silicon, has an oxygen atom layer between the single crystal silicon layer and the wafer composed of the Group IV element containing silicon, and has a planar concentration of oxygen of the oxygen atom layer of 4 x 1014atoms / cm2or more. 14 atoms / cm2 2 or more.

[0056] If the above-described epitaxial wafer, a very strong gettering layer can be provided in the vicinity of the device region, and thus metal impurities can be reliably removed even in the low-temperature processes in recent years. Further, the epitaxial wafer becomes an epitaxial wafer having a high-quality single crystal silicon epitaxial layer.

[0057] Effects of the Invention

[0058] As described above, according to the method for manufacturing an epitaxial wafer of the present application, an atomic layer of oxygen can be stably and easily introduced to an epitaxial layer in close proximity to the epitaxial layer. Also, a close proximity gettering substrate having an epitaxial layer of high-quality single crystal silicon with a close proximity gettering effect by the atomic layer of oxygen can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1-A A diagram for illustrating an epitaxial wafer of the present application.

[0060] Figure 1-B A diagram for illustrating an epitaxial wafer of the present application in which a plurality of atomic layers of oxygen and single crystal silicon layers are alternately stacked on a wafer.

[0061] Figure 2 A diagram for illustrating a flow of a method for manufacturing an epitaxial wafer of the present application.

[0062] Figure 3 A diagram for illustrating a transmission electron microscope image of a cross section of a silicon substrate in Example 1 and Comparative Example 1.

[0063] Figure 4 A diagram for illustrating a transmission electron microscope image of a cross section of a silicon substrate in Comparative Example 2. DETAILED DESCRIPTION

[0064] Hereinafter, the present application will be described in detail, but the present application is not limited thereto.

[0065] As described above, there is a demand for a method for manufacturing an epitaxial wafer and an epitaxial wafer having a high-quality single crystal silicon epitaxial layer while stably introducing an atomic layer of oxygen to the epitaxial layer without special equipment or a complicated process.

[0066] The present inventors have made intensive studies in view of the above technical problems, and as a result, have found that, by a method for manufacturing an epitaxial wafer described below, dislocations and stacking faults are not formed in an epitaxial layer on an atomic layer of oxygen, and the atomic layer of oxygen can be stably and easily introduced to the epitaxial layer, thereby completing the present application. The method for manufacturing an epitaxial wafer in which a single crystal silicon layer is formed on a wafer composed of a Group IV element including silicon, includes: a step of removing a natural oxide film on a surface of the wafer composed of the Group IV element including silicon in a hydrogen-containing atmosphere; a step of oxidizing the wafer after the natural oxide film is removed, thereby forming an atomic layer of oxygen; and a step of epitaxially growing a single crystal silicon on the surface of the wafer after the atomic layer of oxygen is formed, and in the method, a planar concentration of oxygen of the atomic layer of oxygen is set to 4 x 1014atoms / cm 14 or less. 2 Hereinafter.

[0067] Further, the inventors of the present application found that by the following epitaxial wafer, since a very strong gettering layer is present in the vicinity of the device region, even in the low-temperature processes in recent years, metal impurities can be reliably removed, and an epitaxial layer of high-quality single crystal silicon is obtained, thereby completing the present application. The epitaxial wafer is an epitaxial wafer having a single crystal silicon layer on a wafer composed of Group IV elements including silicon, having an oxygen atom layer between the single crystal silicon layer and the wafer composed of Group IV elements including silicon, the oxygen atom layer having a planar concentration of oxygen of 4 x 1014atoms / cm2or more and 2 x 1015atoms / cm2or less. 14 atoms / cm2 2 or more.

[0068] Hereinafter, the present application will be described with reference to the drawings.

[0069] Figure 1-A A diagram showing the epitaxial wafer of the present application. The epitaxial wafer 10 of the present application is an epitaxial wafer having a single crystal silicon layer 3 on a wafer 1 composed of Group IV elements including silicon, and having an oxygen atom layer 2 between the single crystal silicon layer 3 and the wafer 1 composed of Group IV elements including silicon.

[0070] The epitaxial wafer 10 of the present application has an oxygen atom layer 2 having a planar concentration of oxygen of 4 x 1014atoms / cm2or more and 2 x 1015atoms / cm2or less. 14 atoms / cm2 2 or more. If it is an epitaxial wafer within the above range, the epitaxial layer of single crystal silicon has few stacking faults. Further, there is no lower limit to the planar concentration of oxygen, and it is only required to be greater than 0.

[0071] In the present application, the wafer 1 composed of Group IV elements including silicon is not particularly limited, and for example, single crystal silicon, SiGe, SiGeC can be used.

[0072] The wafer 1 can be manufactured in any manner. For example, a wafer manufactured by the Czochralski method (hereinafter referred to as the CZ method) can be used, and a wafer manufactured by the floating zone method (hereinafter referred to as the FZ method) can be used. Further, a wafer in which Group IV elements including silicon are epitaxially grown on a single crystal silicon wafer manufactured by the CZ method or the FZ method can be used.

[0073] Further, Figure 1-B A diagram showing the epitaxial wafer of the present application in which a plurality of oxygen atom layers and single crystal silicon layers are alternately stacked on a wafer. As shown in FIG. 2, the epitaxial wafer of the present application can be an epitaxial wafer in which a plurality of oxygen atom layers 2 and single crystal silicon layers 3 are alternately stacked on a wafer 1 composed of Group IV elements including silicon. At this time, the uppermost surface is a single crystal silicon layer. Figure 1-B

[0074] ​The planar concentration of oxygen in the oxygen atom layer can be measured by SIMS (Secondary Ion Mass Spectrometry). When SIMS is used to measure a Si including an oxide layer, a peak is formed at the depth of the Si where the oxide layer is formed. The planar concentration of oxygen can be calculated by integrating the product of the volume concentration and the depth in the vicinity of the peak.

[0075] Figure 2 A flow chart showing the process of the method of manufacturing an epitaxial wafer according to the present application. It shows, respectively, S11, a process of preparing a wafer composed of Group IV elements including silicon, S12, a process of removing a natural oxide film in a hydrogen-containing atmosphere, S13, a process of forming an oxygen atom layer, and S14, a process of epitaxially growing a single crystal silicon.

[0076] In the present application, as the wafer composed of Group IV elements including silicon, a single crystal silicon, SiGe, SiGeC, or the like can be used.

[0077] The method of manufacturing the wafer is not particularly limited. A wafer manufactured by the CZ method can be used, or a wafer manufactured by the FZ method can be used. In addition, a wafer manufactured by epitaxially growing Group IV elements including silicon on a single crystal silicon wafer manufactured by the CZ method or the FZ method can be used.

[0078] In particular, as the wafer composed of Group IV elements including silicon, a single crystal silicon wafer is preferably used.

[0079] In this way, by using a single crystal silicon wafer as the wafer composed of Group IV elements including silicon, the versatility is improved. At this time, as the silicon wafer, a wafer on which ion implantation and heat treatment have been performed can be used.

[0080] The process S12 of removing a natural oxide film in a hydrogen-containing atmosphere according to the present application is a process of removing a natural oxide film by a reducing dry process using hydrogen. The inventors of the present application have found that, when a wet process such as HF or BHF is used, the natural oxide film cannot be sufficiently removed, or oxidation occurs immediately after the natural oxide film is removed, and thus the single crystal silicon cannot be epitaxially grown stably.

[0081] In the process of removing the natural oxide film, the natural oxide film is preferably removed by heating the wafer in a hydrogen-containing atmosphere, and further, the natural oxide film is more preferably removed by heating the wafer to a temperature of 800°C or higher and 1250°C or lower, and maintaining the temperature in this range for 1 second or longer and 5 minutes or shorter.

[0082] Thus, the natural oxide film can be removed more stably.

[0083] It is further preferable to remove the natural oxide film by using a hydrogen-containing plasma in the step of removing the natural oxide film.

[0084] Thus, in the case of removing the natural oxide film by using a hydrogen-containing plasma, the natural oxide film can be removed at a lower temperature than in the case of removing the natural oxide film by heating in a hydrogen-containing atmosphere. Therefore, this is effective particularly when the wafer contains Ge and Sn, which have low heat resistance. For example, in the case of SiGe, the higher the ratio of Ge, the lower the heat resistance temperature.

[0085] In addition, in the case of removing the natural oxide film by using a hydrogen-containing plasma, the wafer can be removed at room temperature, or can be heated to remove the natural oxide film.

[0086] In the step S13 of forming the oxygen atom layer, the planar concentration of oxygen of the oxygen atom layer is set to 4 x 10 14 atoms / cm 2 By setting to the above range, no defects are formed in the epitaxial layer. This is because the crystallinity of the substrate can be maintained when the oxidation amount (planar concentration of oxygen of the oxygen atom layer) is small. Therefore, the planar concentration of oxygen has no lower limit value, and is greater than 0. In the case where the oxidation amount is large, the epitaxial layer becomes polycrystal silicon or amorphous silicon. The inventors of the present application have found that if the planar concentration of oxygen of the oxygen atom layer exceeds 4 x 10 14 atoms / cm 2 , defects are formed, or amorphous silicon is formed.

[0087] There are several methods of oxidizing the wafer, and in the present application, for example, by adjusting the time of exposing the wafer to an oxygen-containing atmosphere, an oxygen atom layer having a desired planar concentration of oxygen can be formed.

[0088] In the step of forming the oxygen atom layer, it is preferable to oxidize the wafer in an oxygen-containing atmosphere.

[0089] If the wafer is oxidized in the above environment, the wafer can be oxidized simply without preparing a special apparatus. Furthermore, the oxidation can be performed in an atmosphere in which the oxygen concentration is 100%, or in an atmosphere in which an inactive gas such as nitrogen, argon, helium, neon, krypton, xenon, or the like is mixed with oxygen. By mixing the inactive gas with oxygen, the processing can be performed safely. Furthermore, the oxidation of the wafer can be performed at room temperature, or can be performed by heating.

[0090] At this time, it is preferable to oxidize the wafer in the atmosphere.

[0091] By setting the step of forming the oxygen atom layer to the above environment, the oxidation can be performed simply without preparing a supply apparatus of an oxygen-containing atmosphere.

[0092] As a gas for epitaxial growth of the single crystal silicon, monosilane and disilane, for example, can be used in the process S14 of causing the single crystal silicon to undergo epitaxial growth. As a carrier gas, nitrogen and hydrogen can also be used. Furthermore, the pressure of the chamber can be any pressure that does not cause a gas phase reaction.

[0093] In the process of causing the single crystal silicon to undergo epitaxial growth, it is preferable to perform epitaxial growth at a temperature of 450°C or higher and 800°C or lower.

[0094] By setting the temperature range as described above in the process of causing the single crystal silicon to undergo epitaxial growth, it is possible to more effectively prevent dislocations and stacking faults from occurring in the epitaxial layer. Since the higher the temperature, the higher the epitaxial growth rate, it is possible to form a thick epitaxial layer in a short time by performing film formation at a high temperature. On the other hand, in the case where a thin epitaxial layer is to be formed, it is possible to perform film formation at a low temperature. In this way, by changing the growth temperature, it is possible to easily obtain an epitaxial layer of a target thickness. Furthermore, when the wafer contains Ge and Sn, which have low heat resistance, in order to prevent a decrease in crystallinity, it is desirable to perform film formation at a low temperature.

[0095] Furthermore, as the epitaxial growth apparatus, a batch type can be used, or a single wafer type can be used.

[0096] Furthermore, the process of oxidizing the wafer to form an oxygen atom layer and the process of causing the single crystal silicon to undergo epitaxial growth can also be alternately performed a plurality of times.

[0097] In this way, by providing a multilayered oxygen atom layer, it is possible to further improve the gettering effect compared to the case where the oxygen atom layer is one layer.

[0098] As described above, according to the method of manufacturing an epitaxial wafer of the present application, it is possible to stably and easily introduce an oxygen atom layer to an epitaxial layer in a manner close to the epitaxial layer. Furthermore, it is possible to obtain an epitaxial wafer having an epitaxial layer of high-quality single crystal silicon.

[0099] Example

[0100] Hereinafter, the present application will be described in detail with examples, but the present application is not limited to this.

[0101] (Example 1)

[0102] Single crystal silicon wafers of the following conductive type, diameter, and crystal orientation were prepared.

[0103] Conductive type of substrate: p-type

[0104] Diameter: 300 mm

[0105] Crystal orientation: (100)

[0106] In order to remove the natural oxide film of the prepared single crystal silicon wafer, hydrogen bake was performed. The temperature was set to 1000°C, and the time was set to 1 minute. Then, the wafer was left in the atmosphere for 4 to 6 hours, thereby forming an oxygen atom layer.

[0107] Next, the single crystal silicon was epitaxially grown on the surface of the single crystal silicon wafer on which the oxygen atom layer was formed in the atmosphere at a temperature of 580°C.

[0108] The planar concentration of oxygen in the oxygen atom layer of the wafer on which epitaxial growth was performed was measured by SIMS measurement, and, in order to evaluate the crystallinity, cross-sectional TEM observation was performed. The observation results are shown in Figure 3 . As shown in Figure 3 , when the planar concentration of oxygen of the oxygen atom layer was 1.4 x 1011 14 atoms / cm 2 , 2.8 x 1011 14 atoms / cm 2 , 4.0 x 1011 14 atoms / cm 2 , i.e., when the planar concentration of oxygen of the oxygen atom layer was 4 x 1011 14 atoms / cm 2 or more, a single crystal silicon layer was formed, and no dislocation and stacking fault were formed in the epitaxial layer.

[0109] (Comparative Example 1)

[0110] The manufacture of the epitaxial wafer and the evaluation were performed under the same conditions as in Example 1, except that, in forming the oxygen atom layer, the time of leaving in the atmosphere was set to 7 hours.

[0111] As shown in Figure 3 , when the planar concentration of oxygen of the oxygen atom layer was 4.8 x 1011 14 atoms / cm 2 , i.e., when the planar concentration of oxygen of the oxygen atom layer exceeded 4 x 1011 14 atoms / cm 2 , a defect was formed.

[0112] (Comparative Example 2)

[0113] The same single crystal silicon wafer as in Example 1 and Comparative Example 1 was prepared, and, after the natural oxide film was removed by a wet process based on HF cleaning, the wafer was left in the atmosphere for 5 hours, thereby forming an oxygen atom layer. Next, epitaxial growth on the surface of the single crystal silicon wafer was performed at a temperature of 580°C.

[0114] The planar concentration of oxygen in the oxygen atom layer of the wafer on which epitaxial growth was performed was measured by SIMS measurement, and, in order to evaluate the crystallinity, cross-sectional TEM observation was performed. The observation results are shown inFigure 4 The planar concentration of oxygen of the oxygen atom layer was 1.8 x 10 15 atoms / cm 2 As shown in FIG. 7, the film formed on the oxygen atom layer was amorphous silicon, not single crystal silicon, i.e., single crystal silicon was not formed. In addition, if the wafer is subjected to heat treatment after film formation, it becomes polycrystal silicon. Figure 4

[0115] In addition, the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and technical solutions having substantially the same configuration as the technical concept described in the claims of the present application and having the same technical effects are all included in the technical scope of the present application.​

Claims

1. A method for manufacturing an epitaxial wafer, comprising forming a single-crystal silicon layer on a wafer composed of group IV elements including silicon, characterized in that, Include: The process of removing the native oxide film on the wafer surface composed of group IV elements including silicon under a hydrogen-containing atmosphere; The process of oxidizing the wafer after removing the natural oxide film to form an oxygen atom layer; and After the formation of the oxygen atom layer, a process is performed in which single-crystal silicon is epitaxially grown on the surface of the wafer using a vapor phase deposition method. The planar concentration of oxygen in the oxygen atom layer is set to 4 × 10⁻⁶. 14 atoms / cm 2 the following.

2. The method for manufacturing an epitaxial wafer according to claim 1, characterized in that, As the wafer composed of group IV elements including silicon, a single-crystal silicon wafer is used.

3. The method for manufacturing an epitaxial wafer according to claim 1, characterized in that, In the process of removing the native oxide film, the native oxide film is removed by heating the wafer in a hydrogen-containing atmosphere.

4. The method for manufacturing an epitaxial wafer according to claim 2, characterized in that, In the process of removing the native oxide film, the native oxide film is removed by heating the wafer in a hydrogen-containing atmosphere.

5. The method for manufacturing an epitaxial wafer according to claim 3, characterized in that, In the process of removing the natural oxide film, the natural oxide film is removed by heating the wafer to a temperature of 800°C or higher and 1250°C or lower, and maintaining this temperature range for more than 1 second and less than 5 minutes.

6. The method for manufacturing an epitaxial wafer according to claim 4, characterized in that, In the process of removing the natural oxide film, the natural oxide film is removed by heating the wafer to a temperature of 800°C or higher and 1250°C or lower, and maintaining this temperature range for more than 1 second and less than 5 minutes.

7. The method for manufacturing an epitaxial wafer according to claim 1, characterized in that, In the process of removing the natural oxide film, the natural oxide film is removed by using hydrogen-containing plasma.

8. The method for manufacturing an epitaxial wafer according to claim 2, characterized in that, In the process of removing the natural oxide film, the natural oxide film is removed by using hydrogen-containing plasma.

9. The method for manufacturing an epitaxial wafer according to claim 1, characterized in that, In the process of forming the oxygen atom layer, the wafer is oxidized in an oxygen-containing atmosphere.

10. The method for manufacturing an epitaxial wafer according to claim 2, characterized in that, In the process of forming the oxygen atom layer, the wafer is oxidized in an oxygen-containing atmosphere.

11. The method for manufacturing an epitaxial wafer according to claim 3, characterized in that, In the process of forming the oxygen atom layer, the wafer is oxidized in an oxygen-containing atmosphere.

12. The method for manufacturing an epitaxial wafer according to claim 4, characterized in that, In the process of forming the oxygen atom layer, the wafer is oxidized in an oxygen-containing atmosphere.

13. The method for manufacturing an epitaxial wafer according to claim 5, characterized in that, In the process of forming the oxygen atom layer, the wafer is oxidized in an oxygen-containing atmosphere.

14. The method for manufacturing an epitaxial wafer according to claim 6, characterized in that, In the process of forming the oxygen atom layer, the wafer is oxidized in an oxygen-containing atmosphere.

15. The method for manufacturing an epitaxial wafer according to claim 7, characterized in that, In the process of forming the oxygen atom layer, the wafer is oxidized in an oxygen-containing atmosphere.

16. The method for manufacturing an epitaxial wafer according to claim 8, characterized in that, In the process of forming the oxygen atom layer, the wafer is oxidized in an oxygen-containing atmosphere.

17. The method for manufacturing an epitaxial wafer according to any one of claims 1 to 16, characterized in that, In the process of forming the oxygen atom layer, the wafer is oxidized in the atmosphere.

18. The method for manufacturing an epitaxial wafer according to any one of claims 1 to 16, characterized in that, In the process of epitaxially growing the single crystal silicon, the epitaxial growth is performed at a temperature of 450°C or higher and 800°C or lower.

19. The method for manufacturing an epitaxial wafer according to any one of claims 1 to 16, characterized in that, The process alternately involves multiple steps of oxidizing the wafer to form an oxygen atom layer and epitaxially growing the single crystal silicon.

Images