Method for manufacturing silicon substrate for quantum computer, silicon substrate for quantum computer, and semiconductor device

Abstract

The present invention is a method for manufacturing a silicon substrate for a quantum computer, the method comprising: a step for forming an Si epitaxial layer by epitaxially growing on a silicon substrate using, as a silicon-based raw material gas, an Si source gas in which the total content of 28Si and 30Si in the entire silicon contained in the silicon-based raw material gas is 99.9% or more; a step for oxidizing the surface of the Si epitaxial layer to form a delta-doped layer of oxygen (O); and a step in which an Si epitaxial layer is formed by epitaxially growing on the delta-doped layer using an Si source gas in which the total content of 28Si and 30Si in the entire silicon contained in the silicon-based raw material gas is 99.9% or more. As a result, provided are: a silicon substrate for a quantum computer, which is capable of suppressing the influence of 29Si and suppressing the influence of nuclear spin; and a method for manufacturing the silicon substrate for a quantum computer.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a silicon substrate for a quantum computer, a silicon substrate for a quantum computer, and a semiconductor device. Background Art

[0002] Quantum computers that use quantum effects such as quantum superposition and quantum entanglement are expected to be computers that can solve calculations that conventional computers cannot solve in real time. Components used in quantum computers are also mounted on semiconductor substrates such as silicon substrates.

[0003] There are several methods for devices used for quantum computers, and the main ones include devices that use superconductors and utilize the Josephson effect, and devices that utilize electron spin (ESR) to convert quantum effects into electrical signals.

[0004] In an element using a silicon substrate and utilizing electron spins, the electron spins placed in a magnetic field are irradiated with microwaves and the frequency is swept to cause resonance, thereby reading quantum effects (Patent Document 1). Prior art literature Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-025657 Patent Document 2: Japanese Patent Application Publication No. 2021-111696 Summary of the invention Problems to be solved by the invention

[0006] When using electron spin in this way, if there are unwanted spin components in the vicinity, the electron spin energy will be split due to the Zeeman effect, and the quantum effect cannot be used for calculation. 28 The Si-rich Si layer is mainly Si-rich Si, which is to minimize the number of 29 Four.

[0007] For this purpose, the following silicon substrate is used, that is, a silicon substrate that has been isotopically enriched. 28 SiH4 gas is formed 28 The silicon substrate of the Si epitaxial layer. In addition, in order to make a single electron layer (if there are multiple electrons, the spins of the electrons interact with each other, making calculations difficult), it is necessary to bind electrons (single electron transistor).

[0008] As the structure used for this purpose, most of them adopt a method of making a fin structure and confining electrons at the front end of the fin, or a silicon on insulator (SOI) structure. Although the fin structure has the advantage of being formed only of silicon, it is difficult to process the surface state of the silicon surface. On the other hand, in the SOI structure, although the influence of the interface between silicon and the oxide film is small, the method of forming the insulating layer is more difficult. That is, even if 28Si is oxidized, the diffusion of silicon during the heat treatment still causes the electrons with nuclear spins to be oxidized. 29 Si has an impact.

[0009] Furthermore, the same phenomenon also occurs during the heat treatment during the formation of SOI by conventional bonding methods. 28 The diffusion of Si makes it impossible to fully utilize 28 Isotope effect of Si.

[0010] The present invention is completed to solve the above-mentioned problem, and provides a silicon substrate for quantum computer and a manufacturing method thereof, wherein the silicon substrate for quantum computer can suppress 29 The influence of Si and suppress the influence of nuclear spin. Means of solving problems

[0011] The present invention is completed in order to achieve the above-mentioned purpose, and provides a method for manufacturing a silicon substrate for a quantum computer, characterized in that it comprises the following steps: 28 Si and 30 The steps of epitaxially growing a Si epitaxial layer on a silicon substrate using a Si source gas in which the total content of Si in the whole silicon contained in the silicon-based raw material gas is 99.9% or more as the silicon-based raw material gas; oxidizing the surface of the Si epitaxial layer to form a delta-doped layer of oxygen (O); and 28 Si and 30 A step of forming a Si epitaxial layer by epitaxially growing the δ-doped layer using a Si source gas in which the total content of Si in the entire silicon contained in the silicon-based raw material gas is 99.9% or more.

[0012] According to such a method for manufacturing a silicon substrate for a quantum computer, a silicon substrate for a quantum computer capable of suppressing the influence of nuclear spins can be manufactured, and a silicon substrate capable of fully utilizing the isotope effect suitable for a quantum computer and easily forming a single-electron transistor can be manufactured.

[0013] In this case, the method for manufacturing a silicon substrate for a quantum computer can be configured as follows: monosilane gas is used as the Si source gas.

[0014] This makes it possible to manufacture a silicon substrate suitable for quantum computers at a lower temperature.

[0015] In this case, the method for manufacturing a silicon substrate for a quantum computer can be as follows: the step of forming the oxygen (O) δ-doped layer and the step of forming the Si epitaxial layer on the δ-doped layer are repeated to form a plurality of pairs of the δ-doped layer and the Si epitaxial layer on the δ-doped layer.

[0016] This makes it possible to manufacture a silicon substrate that is more suitable for use in quantum computers.

[0017] In this case, the method for manufacturing a silicon substrate for a quantum computer may be configured such that the thickness of the outermost Si epitaxial layer of the silicon substrate for a quantum computer is thicker than the thickness of Si epitaxial layers other than the outermost Si epitaxial layer.

[0018] In this way, a silicon substrate further suitable for use in a quantum computer can be manufactured.

[0019] In this case, the method for manufacturing a silicon substrate for a quantum computer can be configured as follows: a SOI structure can be fabricated by subjecting the silicon substrate for a quantum computer to a heat treatment so that the plurality of δ-doped layers are integrated.

[0020] In this way, a silicon substrate having an SOI structure suitable for use in a quantum computer can be manufactured.

[0021] In this case, the method for manufacturing a silicon substrate for a quantum computer can be set as follows: a silicon substrate having a resistivity of 1000 Ω·cm or more is used as the silicon substrate.

[0022] Thereby, it is possible to manufacture a silicon substrate for a quantum computer that can extract a signal obtained by spin resonance stably and without distortion.

[0023] Furthermore, the present invention provides a method for manufacturing a silicon substrate for a quantum computer, characterized in that it comprises the following steps: using 28 Si source gas is used as silicon raw material gas to perform epitaxial growth on the silicon substrate, thereby forming 28 Si epitaxial layer step; 28 The step of oxidizing the surface of the Si epitaxial layer to form a delta-doped layer of oxygen (O); and 28 Si source gas is epitaxially grown on the delta-doped layer to form 28 Si epitaxial layer step.

[0024] According to such a method for manufacturing a silicon substrate for a quantum computer, a silicon substrate for a quantum computer capable of suppressing the influence of nuclear spins can be manufactured, and a silicon substrate capable of fully utilizing the isotope effect suitable for a quantum computer and easily forming a single-electron transistor can be manufactured.

[0025] In this case, the method for manufacturing a silicon substrate for a quantum computer can be as follows: 28 Si monosilane gas as the 28 Si source gas.

[0026] This makes it possible to manufacture a silicon substrate suitable for quantum computers at a lower temperature.

[0027] In this case, the method for manufacturing a silicon substrate for a quantum computer can be as follows: the steps of forming the oxygen (O) delta-doped layer and forming the above-mentioned on the delta-doped layer are repeated. 28 The step of forming a Si epitaxial layer to form a plurality of pairs of the δ-doped layers and the δ-doped layers located on the δ-doped layers 28 Si epitaxial layer.

[0028] This makes it possible to manufacture a silicon substrate that is more suitable for use in quantum computers.

[0029] In this case, the method for manufacturing a silicon substrate for a quantum computer can be as follows: 28 The thickness of the Si epitaxial layer is greater than that of the outermost layer. 28 Other than Si epitaxial layer 28 The thickness of the Si epitaxial layer is thicker.

[0030] In this way, a silicon substrate further suitable for use in a quantum computer can be manufactured.

[0031] In this case, the method for manufacturing a silicon substrate for a quantum computer may be as follows: the SOI structure may be fabricated by subjecting the silicon substrate for a quantum computer to heat treatment so that the plurality of δ-doped layers are integrated.

[0032] In this way, a silicon substrate having an SOI structure suitable for use in a quantum computer can be manufactured.

[0033] In this case, the method for manufacturing a silicon substrate for a quantum computer can be set as follows: a silicon substrate having a resistivity of 1000 Ω·cm or more is used as the silicon substrate.

[0034] Thereby, it is possible to manufacture a silicon substrate for a quantum computer that can extract a signal obtained by spin resonance stably and without distortion.

[0035] Furthermore, the present invention is completed in order to achieve the above-mentioned object, and provides a silicon substrate for quantum computers, which comprises: a silicon substrate; a Si epitaxial layer, which is an epitaxial layer located on the silicon substrate and has 28 Si and 30The total content of Si in the silicon of the epitaxial layer is more than 99.9%; the SiO2 layer is located on the Si epitaxial layer and has 28 Si and 30 The total content of Si in the SiO2 layer is 99.9% or more; and a Si epitaxial layer, which is an epitaxial layer located on the SiO2 layer and has 28 Si and 30 The total content of Si in the entire silicon of the epitaxial layer is 99.9% or more.

[0036] According to such a silicon substrate for quantum computer, a silicon substrate for quantum computer capable of suppressing the influence of nuclear spin can be manufactured, and a silicon substrate capable of fully utilizing the isotope effect suitable for quantum computer and easily forming a single electron transistor can be manufactured.

[0037] In this case, the silicon substrate for a quantum computer can be set as follows: the SiO 2 layer is a delta-doped layer of oxygen (O).

[0038] This can provide a silicon substrate having a delta-doped layer suitable for use in a quantum computer.

[0039] In this case, the silicon substrate for a quantum computer can be as follows: the SiO 2 layer is a buried oxide film (BOX) layer in the SOI structure.

[0040] This can provide a silicon substrate having an SOI structure suitable for use in a quantum computer.

[0041] In this case, a semiconductor device including elements on a silicon substrate for a quantum computer can be provided.

[0042] This enables a semiconductor device in which the influence of nuclear spins is suppressed.

[0043] Furthermore, the present invention provides a silicon substrate for a quantum computer, comprising: a silicon substrate; 28 A Si epitaxial layer, which is located on the silicon substrate; 28 A SiO2 layer located on the 28Si epitaxial layer; and 28 Si epitaxial layer, which is located in the 28 On the SiO2 layer.

[0044] According to such a silicon substrate for quantum computer, a silicon substrate for quantum computer capable of suppressing the influence of nuclear spin can be manufactured, and a silicon substrate capable of fully utilizing the isotope effect suitable for quantum computer and easily forming a single electron transistor can be manufactured.

[0045] At this time, the following quantum computer silicon substrate can be used:28 The SiO2 layer is a delta-doped layer of oxygen (O).

[0046] This can provide a silicon substrate having a delta-doped layer suitable for use in a quantum computer.

[0047] At this time, the following quantum computer silicon substrate can be used: 28 The SiO2 layer is the buried oxide film (BOX) layer in the SOI structure.

[0048] This can provide a silicon substrate having an SOI structure suitable for use in a quantum computer.

[0049] In this case, a semiconductor device can be provided, characterized in that an element is provided on a silicon substrate for a quantum computer.

[0050] This enables a semiconductor device in which the influence of nuclear spins is suppressed. Effects of the Invention

[0051] As described above, according to the method for manufacturing a silicon substrate for a quantum computer of the present invention, a silicon substrate for a quantum computer capable of suppressing the influence of nuclear spin can be manufactured, and a silicon substrate capable of fully exerting the isotope effect suitable for a quantum computer and easily forming a single-electron transistor can be manufactured. According to the method for manufacturing a silicon substrate for a quantum computer of the present invention, a silicon substrate for a quantum computer capable of suppressing the influence of nuclear spin can be manufactured, and a silicon substrate capable of fully exerting the isotope effect suitable for a quantum computer and easily forming a single-electron transistor can be manufactured. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 A schematic diagram for explaining an example of the structure of the silicon substrate for a quantum computer of the present invention is shown. Figure 2 A schematic diagram for explaining another example of the structure of the silicon substrate for a quantum computer of the present invention is shown. Figure 3 A schematic diagram for explaining the flow of the method for manufacturing a silicon substrate for a quantum computer according to the present invention is shown. DETAILED DESCRIPTION

[0053] Hereinafter, the present invention will be described in detail, but the present invention is not limited to these descriptions.

[0054] As described above, a silicon substrate for a quantum computer and a method for manufacturing the same are sought, wherein the silicon substrate for a quantum computer can suppress 29 The influence of Si and suppress the influence of nuclear spin.

[0055] The inventors of the present invention have repeatedly studied the above problems and found a method for manufacturing a silicon substrate for a quantum computer, which comprises the following steps: 28 Si and 30 The steps of epitaxially growing a Si epitaxial layer on a silicon substrate using a Si source gas in which the total content of Si in the whole silicon contained in the silicon-based raw material gas is 99.9% or more as the silicon-based raw material gas; oxidizing the surface of the Si epitaxial layer to form a delta-doped layer of oxygen (O); and 28 Si and 30 A step of epitaxially growing a Si source gas in which the total content of Si in the whole silicon contained in the silicon-based raw material gas is more than 99.9% on the δ-doped layer to form a Si epitaxial layer; through the manufacturing method of the silicon substrate for quantum computer, a silicon substrate for quantum computer capable of suppressing the influence of nuclear spin can be manufactured, and a silicon substrate can be manufactured, which can give full play to the isotope effect suitable for quantum computer and easily form a single electron transistor, thereby completing the present invention.

[0056] Furthermore, the inventors have discovered a method for manufacturing a silicon substrate for a quantum computer, which comprises the following steps: 28 Si source gas is used as silicon raw material gas to perform epitaxial growth on the silicon substrate, thereby forming 28 Si epitaxial layer step; 28 The step of oxidizing the surface of the Si epitaxial layer to form a delta-doped layer of oxygen (O); and 28 Si source gas is epitaxially grown on the delta-doped layer to form 28 The step of Si epitaxial layer; through the manufacturing method of the silicon substrate for quantum computer, a silicon substrate for quantum computer that can suppress the influence of nuclear spin can be manufactured, and a silicon substrate that can fully exert the isotope effect suitable for quantum computer and easily form single-electron transistor can be manufactured, thereby completing the present invention.

[0057] Furthermore, the inventors have repeatedly studied the above-mentioned problems and found a silicon substrate for quantum computers, which comprises: a silicon substrate; a Si epitaxial layer, which is an epitaxial layer located on the silicon substrate and has 28 Si and 30 The total content of Si in the silicon of the epitaxial layer is more than 99.9%; the SiO2 layer is located on the Si epitaxial layer and has 28 Si and 30 The total content of Si in the SiO2 layer is 99.9% or more; and a Si epitaxial layer, which is an epitaxial layer located on the SiO2 layer and has28 Si and 30 The total content of Si in the silicon of the epitaxial layer is more than 99.9%; through the silicon substrate for quantum computer, a silicon substrate for quantum computer that can suppress the influence of nuclear spin can be made, and it can become a silicon substrate that can fully exert the isotope effect suitable for quantum computer and easily form single-electron transistor, thereby completing the present invention.

[0058] Furthermore, the present inventors have discovered a silicon substrate for a quantum computer, comprising: a silicon substrate; 28 A Si epitaxial layer, which is located on the silicon substrate; 28 The SiO2 layer is located in the 28 On the Si epitaxial layer; and 28 Si epitaxial layer, which is located in the 28 On the SiO2 layer; through the silicon substrate for quantum computers, a silicon substrate for quantum computers that can suppress the influence of nuclear spin can be made, and it can become a silicon substrate that can fully exert the isotope effect suitable for quantum computers and easily form single-electron transistors, thereby completing the present invention.

[0059] Hereinafter, description will be given with reference to the drawings.

[0060] Below, " 28 Si" as an example to explain the definition of the term, about other isotopes ( 30 Si, etc.), sometimes the same representation is used.

[0061] In this specification, the silicon-based raw material gas " 28 "Si source gas" means a gas having 28 A gas containing silicon, wherein the content of Si in the total amount of silicon in the gas containing silicon is 99.9% or more. 28 Si monosilane gas" (sometimes also marked as " 28 SiH4") means having 28 A monosilane gas in which Si accounts for 99.9% or more of the total silicon in the monosilane (SiH4) gas. 28 4. 29 4. 30 The natural abundance of these isotopes is 92.23%, 4.67%, and 3.1%, respectively. For example, the silicon-containing gas (silane-based gas) containing natural Si isotope composition can be centrifuged to produce 28 Si source gas. About 30 Si source gas and 28 Si and 30A "Si source gas" in which the total content of Si in the entire silicon contained in the silicon-based raw material gas is 99.9% or more can also be produced in the same manner.

[0062] In this manual, " 28 "Si epitaxial layer" means having 28 An epitaxial layer having a composition in which Si accounts for 99.9% or more of the total silicon in the epitaxial layer. 28 It is obtained by epitaxial growth using Si source gas.

[0063] In this manual, " 28 SiO2" means having 28 SiO2 is composed of Si with a content of 99.9% or more of the total silicon content of SiO2. 28 The Si epitaxial layer is obtained by oxidation.

[0064] In this specification, "δ-doped layer" refers to a layer into which an element different from the base material is introduced at a monatomic layer level. For example, a δ-doped layer of oxygen (O) includes a layer into which less than a monatomic layer (1.36×10 15 atoms / cm 2 ) In the case of oxygen. In addition, regarding the δ doping method, there is a method described in Patent Document 2, for example.

[0065] [Silicon substrate for quantum computers] (First Embodiment) The inventors have repeatedly studied the above problems and found a silicon substrate for quantum computers, which comprises: a silicon substrate; a Si epitaxial layer, which is an epitaxial layer located on the silicon substrate and has 28 Si and 30 The total content of Si in the silicon of the epitaxial layer is more than 99.9%; the SiO2 layer is located on the Si epitaxial layer and has 28 Si and 30 The total content of Si in the SiO2 layer is 99.9% or more; and a Si epitaxial layer, which is an epitaxial layer located on the SiO2 layer and has 28 Si and 30 The total content of Si in the silicon of the epitaxial layer is 99.9% or more; the silicon substrate for quantum computers can be used to suppress 29 Silicon substrate for quantum computers that suppresses the influence of nuclear spins while reducing the influence of Si.

[0066] The Si epitaxial layer in the silicon substrate for quantum computers of the present invention has 28 Si and 30The total content of Si in the entire silicon of the epitaxial layer only needs to be 99.9% or more. 28 Si and 30 Si both. Can be 28 When the content of Si in the total silicon of the epitaxial layer is 99.9% or more, 30 When the Si content is 99.9% or more.

[0067] In this case, the SiO2 layer is preferably a delta-doped layer of oxygen (O). Such a silicon substrate for quantum computers can be a silicon substrate having a delta-doped layer suitable for quantum computers.

[0068] Furthermore, it is preferred that the SiO2 layer is a buried oxide film (BOX) layer in the SOI structure. Such a silicon substrate for quantum computers can be a silicon substrate with an SOI structure suitable for quantum computers.

[0069] Furthermore, it is preferable that an element is provided on the silicon substrate for quantum computers. Such a semiconductor device can be a semiconductor device in which the influence of nuclear spins is suppressed.

[0070] A more detailed embodiment will be described with reference to the following second embodiment, which corresponds to a composition in which the content of 28Si in the silicon substrate for quantum computer of the first embodiment is set to 99.9% or more in the entire silicon of the epitaxial layer.

[0071] (Second Embodiment) Furthermore, the present inventors have discovered a silicon substrate for a quantum computer, comprising: a silicon substrate; 28 Si epitaxial layer, which is located on a silicon substrate; 28 SiO2 layer, which is located 28 On the Si epitaxial layer; and 28 Si epitaxial layer, which is located 28 SiO2 layer; through this quantum computer silicon substrate, it can become a kind of 29 As described above, the silicon substrate for quantum computer of the second embodiment of the present invention is equivalent to the silicon substrate for quantum computer of the first embodiment. 28 The content of Si in the entire silicon of the epitaxial layer is set to be 99.9% or more.

[0072] Figure 1 An example of the structure of the silicon substrate for quantum computer of the present invention is shown in FIG. The silicon substrate for quantum computer of the second embodiment comprises: a silicon substrate 1; 28 Si epitaxial layer 2, which is located on the silicon substrate 1; 28 SiO2 layer 3, which is located28 On the Si epitaxial layer 2; and 28 Si epitaxial layer 2, which is located 28 On SiO2 layer 3.

[0073] Figure 1 The silicon substrate used in quantum computers is shown in 28 The SiO 2 layer 3 can be a delta-doped layer of oxygen (O). Figure 2 The figure shows a multilayer (oxygen (O) delta doped layer 3A and adjacent 28 The Si epitaxial layer 2 is an example of a δ-doped layer 3A of oxygen (O) with multiple pairs of δ-doped layers. However, the δ-doped layer of oxygen (O) may also be as follows: Figure 1 of 28 The SiO2 layer 3 is shown as a single layer (1 layer).

[0074] and, Figure 1 The silicon substrate used in quantum computers is shown in 28 The SiO2 layer 3 can be set as a buried oxide film (BOX) layer in the SOI structure. 28 The film thickness of the SiO2 layer can be set to about 0.01 to 1 μm.

[0075] The silicon substrate 1 used in the silicon substrate for quantum computer of the present invention is described. The silicon substrate 1 is not particularly limited as long as it can be deposited on the substrate. 28 A Si epitaxial layer is sufficient. The diameter, thickness, dopant, etc. are not particularly limited. In a quantum computer, microwaves, etc. are used to read out the spin state of electrons, etc. that can show quantized behavior. For this reason, a high-resistance substrate is preferably used to reduce the distortion of signals in the telecommunication transmission path. A high-resistance substrate having a resistivity of about 1000Ω·cm or more is particularly preferred. Thus, a silicon substrate for a quantum computer can be obtained that can stably and distortion-free extract signals obtained by spin resonance. The upper limit of the resistivity of the silicon substrate is not particularly limited, for example, it can be set to 100000Ω·cm or less.

[0076] A semiconductor device in which elements are provided on the silicon substrate for a quantum computer of the present invention can be a semiconductor device in which the influence of nuclear spins is suppressed.

[0077] [Method for manufacturing silicon substrate for quantum computer] (Third Embodiment) Next, a method for manufacturing a silicon substrate for a quantum computer according to a third embodiment of the present invention is described. The method for manufacturing a silicon substrate for a quantum computer according to the present invention comprises the following steps: 28 Si and 30The steps of epitaxially growing a Si epitaxial layer on a silicon substrate using a Si source gas in which the total content of Si in the whole silicon contained in the silicon-based raw material gas is 99.9% or more as the silicon-based raw material gas; oxidizing the surface of the Si epitaxial layer to form a delta-doped layer of oxygen (O); and 28 Si and 30 A step of forming a Si epitaxial layer by epitaxially growing the Si source gas on the delta-doped layer using a Si source gas in which the total content of Si in the entire silicon contained in the silicon-based raw material gas is 99.9% or more.

[0078] In the method for producing a silicon substrate for a quantum computer according to the third embodiment of the present invention, the silicon-based raw material gas is 28 Si and 30 The Si source gas may contain 99.9% or more of the total content of Si in the entire silicon contained in the silicon-based raw material gas. 28 Si and 30 Si both. Also includes 28 When the content of Si in the total silicon contained in the silicon-based raw material gas is 99.9% or more and 30 When the Si content is 99.9% or more.

[0079] It is preferable to use monosilane gas as the Si source gas. This allows the manufacture of a silicon substrate suitable for a quantum computer at a lower temperature.

[0080] Preferably, the steps of forming a delta-doped layer of oxygen (O) and forming a Si epitaxial layer on the delta-doped layer are repeated to form a plurality of pairs of delta-doped layers and Si epitaxial layers on the delta-doped layers. Thus, a silicon substrate more suitable for quantum computers can be manufactured.

[0081] Furthermore, the thickness of the outermost Si epitaxial layer of the silicon substrate for quantum computers is preferably made thicker than the thickness of the Si epitaxial layers other than the outermost Si epitaxial layer. Thus, a silicon substrate further suitable for quantum computers can be manufactured.

[0082] At this time, it is preferred to use a silicon substrate having a resistivity of 1000 Ω·cm or more as the silicon substrate. Thus, a silicon substrate for a quantum computer can be manufactured, which can stably extract a signal obtained by spin resonance without distortion. The upper limit of the resistivity of the silicon substrate is not particularly limited, and can be set to, for example, 100,000 Ω·cm or less.

[0083] A more detailed embodiment is described by the following fourth embodiment, which is equivalent to the method for manufacturing a silicon substrate for a quantum computer of the third embodiment. 28The content of Si in the entire silicon contained in the silicon-based source gas is set to a composition of 99.9% or more.

[0084] (Fourth Embodiment) Furthermore, the method for manufacturing a silicon substrate for a quantum computer according to the fourth embodiment of the present invention comprises the following steps: 28 Si source gas is used as silicon raw material gas to perform epitaxial growth on the silicon substrate, thereby forming 28 The step of Si epitaxial layer; 28 The step of oxidizing the surface of the Si epitaxial layer to form a delta-doped layer of oxygen (O); and 28 The Si source gas is used to perform epitaxial growth on the δ-doped layer, thereby forming 28 As described above, the method for manufacturing a silicon substrate for a quantum computer according to the fourth embodiment of the present invention is equivalent to the method for manufacturing a silicon substrate for a quantum computer according to the third embodiment of the present invention. 28 The content of Si in the total silicon contained in the silicon-based raw material gas is set to 99.9% or more. This will be described in detail below.

[0085] First, if Figure 3 As shown in (A), a silicon substrate 1 is prepared.

[0086] Then, if Figure 3 As shown in (B), epitaxial growth (deposition) is performed on the silicon substrate 1 to form 28 Si epitaxial layer 2. At this time, chemical vapor deposition (CVD) can form an epitaxial layer with good crystallinity. During epitaxial growth, as a silicon-based raw material gas, for example, a silicon-based raw material gas obtained by isotope enrichment is used. 28 Si source gas. 28 Si source gas is preferably used 28 Si monosilane gas (28SiH4). This allows epitaxial growth at a lower temperature.

[0087] Moreover, at this time 28 The thickness of the Si epitaxial layer 2 is not particularly limited, and a thickness of about 0.01 to 1 μm is sufficient. This is also appropriate from the following considerations: Taking the nuclear magnetic resonance (NMR) spectrum of Si as an example, it can be seen that the interaction between electron spins and nuclear spins is the strongest when they are adjacent to each other, and the effect becomes smaller when they are separated by several atoms.

[0088] Then, if Figure 3 As shown in (C), an oxide film is formed to bind electrons. 28 SiO2 layer. Figure 3 In the example of FIG. 1 , the delta-doped layer 3A of oxygen (O) is formed by the delta-doping method of oxygen (O).

[0089] By using the delta doping method 28 The surface of the Si epitaxial layer is oxidized to form a delta-doped layer 3A of oxygen (O), thereby making the silicon of the insulating film into silicon oxide ( 28 SiO2), which can avoid the influence of electron-nuclear spin interaction.

[0090] Then, if Figure 3 As shown in (D), a doped layer is deposited on top of this δ-doped layer. 28 Si epitaxial layer 2. With the first layer 28 The same is true for the Si epitaxial layer 2. The CVD method can form an epitaxial layer with good crystallinity. The raw material gas is an isotope-enriched 28 SiH4 etc. 28 Si source gas. Moreover, the thickness of the epitaxial layer at this time does not need to be as thick as the first layer. 28 The thickness of the Si epitaxial layer 2 can be appropriately adjusted so as to be able to confine electrons, and can be set to, for example, about 0.001 to 0.5 μm.

[0091] It is also possible to directly manufacture a device with such a structure. However, the insulating layer formed by the above steps may be insufficiently insulated because oxygen is inserted only at the atomic level, as is known as delta doping. Therefore, it is also preferable to repeat the steps of Figure 3 (C) the step of forming the oxygen (O) delta-doped layer 3A, and Figure 3 (D) is formed on the δ-doped layer 28 The steps of Si epitaxial layer 2 are as follows Figure 3 As shown in (E), multiple pairs of oxygen (O) δ-doped layers 3A and δ-doped layers located on the δ-doped layers are formed. 28 Si epitaxial layer. This can become a silicon substrate further suitable for quantum computers.

[0092] Then, if Figure 3 As shown in (F), multiple δ-doped layers can be further oxidized and integrated by heat treatment to form a thicker insulating layer. The thicker insulating layer thus obtained can form an SOI structure that functions as a buried oxide film (BOX) layer 3B. Thus, it can become a silicon substrate that is further suitable for quantum computers.

[0093] The number of times the δ-doped layer 3A of oxygen (O) is stacked and the number of times the Si epitaxial layer 2 is stacked on the δ-doped layer 28 can be appropriately changed in accordance with the characteristics and design of the device. Furthermore, when integrating the plurality of δ-doped layers by oxidation, it is preferred to preliminarily make the outermost layer 28 The Si epitaxial layer 2 is larger than the outermost layer 28 Other than Si epitaxial layer 28The thickness of the Si epitaxial layer is thicker. For example, it can be set to a thickness of about 0.002 to 1 μm. If this is done, even if oxidation is performed, the outermost layer 28 The Si epitaxial layer 2 does not disappear either.

[0094] By using the rich 28 Si layer ( 28 Si epitaxial layer), it is also possible to form a rich 28 Si oxide film ( 28 SiO2 layer). [Example]

[0095] Hereinafter, the present invention will be specifically described with reference to Examples, but these Examples are not intended to limit the present invention.

[0096] (Example) Prepare a boron-doped silicon substrate (resistance: 1000Ω·cm) with a diameter of 300 mm. 28 SiH4 (isotope 99.94%) was used as the raw material for silicon epitaxial growth. A 1 μm film was formed under reduced pressure conditions of 850°C and 100 Torr (13332 Pa). Then, the film was placed in the atmosphere for 2 hours to form a 28 After the natural oxide film composed of SiO2 (δ doping with oxygen), 28 SiH4 (isotope 99.94%) was used as a raw material to form a 3nm silicon epitaxial layer under reduced pressure conditions of 850°C and 100Torr (13332Pa). Further, the following steps were repeated 4 times: placing in the atmosphere for 2 hours to form 28 After the natural oxide film composed of SiO2 (δ doping with oxygen), 28 SiH4 (isotope 99.94%) was used as the raw material to form a 3nm silicon epitaxial layer under reduced pressure conditions of 850°C and 100Torr (13332Pa). 28 SiH4 (isotope 99.94%) was used as the raw material to form a 100nm silicon epitaxial layer at a temperature of 850℃ and a pressure of 100Torr (13332Pa). Finally, a heat treatment was performed at 800℃ for 10 minutes to oxidize the δ-doped layer of oxygen to form an oxide film (buried oxide film (BOX) layer), and the top layer was made with 28 SOI substrate with Si epitaxial layer.

[0097] As described above, according to the embodiments of the present invention, a silicon substrate for a quantum computer capable of suppressing the influence of nuclear spin can be manufactured, and a silicon substrate capable of fully utilizing the isotope effect suitable for a quantum computer and easily forming a single electron transistor can be obtained.

[0098] This specification includes the following aspects. [A]: A method for manufacturing a silicon substrate for a quantum computer, comprising the following steps: By using 28 Si and 30 A step of using a Si source gas in which the total Si content in the entire silicon contained in the silicon-based raw material gas is 99.9% or more to perform epitaxial growth on a silicon substrate as the silicon-based raw material gas to form a Si epitaxial layer; a step of oxidizing the surface of the Si epitaxial layer to form a delta-doped layer of oxygen (O); and By using 28 Si and 30 A step of forming a Si epitaxial layer by epitaxially growing the δ-doped layer using a Si source gas in which the total content of Si in the entire silicon contained in the silicon-based raw material gas is 99.9% or more. [B]: The method for producing a silicon substrate for a quantum computer according to [A] above, wherein monosilane gas is used as the Si source gas. [C]: A method for manufacturing a silicon substrate for a quantum computer as described in [A] or [B] above, wherein the steps of forming a δ-doped layer of oxygen (O) and forming the Si epitaxial layer on the δ-doped layer are repeated to form a plurality of pairs of the δ-doped layers and the Si epitaxial layers located on the δ-doped layers. [D]: The method for manufacturing a silicon substrate for a quantum computer as described in [C] above, wherein the thickness of the outermost Si epitaxial layer of the silicon substrate for a quantum computer is made thicker than the thickness of Si epitaxial layers other than the outermost Si epitaxial layer. [E]: The method for manufacturing a silicon substrate for a quantum computer as described in [D] above, wherein the SOI structure is produced by integrating the plurality of δ-doped layers by heat treating the silicon substrate for a quantum computer. [1]: A method for manufacturing a silicon substrate for a quantum computer, comprising the following steps: By using 28 Si source gas is used as silicon raw material gas to perform epitaxial growth on the silicon substrate, thereby forming 28 Si epitaxial layer step; Regarding the 28A step of oxidizing the surface of the Si epitaxial layer to form a delta-doped layer of oxygen (O); and By using 28 Si source gas is epitaxially grown on the delta-doped layer to form 28 Si epitaxial layer step. [2]: The method for manufacturing a silicon substrate for a quantum computer as described in [1] above, wherein: 28 Si monosilane gas as the 28 Si source gas. [3]: The method for manufacturing a silicon substrate for a quantum computer as described in [1] or [2] above, wherein the steps of forming the δ-doped layer of oxygen (O) and forming the δ-doped layer on the δ-doped layer are repeated. 28 The step of forming a Si epitaxial layer to form a plurality of pairs of the δ-doped layers and the δ-doped layers located on the δ-doped layers 28 Si epitaxial layer. [4]: The method for manufacturing a silicon substrate for a quantum computer as described in [3] above, wherein the outermost layer of the silicon substrate for a quantum computer is 28 The thickness of the Si epitaxial layer is greater than that of the outermost layer. 28 Other than Si epitaxial layer 28 The thickness of the Si epitaxial layer is thicker. [5]: The method for manufacturing a silicon substrate for a quantum computer as described in [4] above, wherein the SOI structure is produced by integrating the plurality of δ-doped layers by heat treating the silicon substrate for a quantum computer. [6]: A method for manufacturing a silicon substrate for a quantum computer as described in [A], [B], [C], [D], [E], [1], [2], [3], [4] or [5] above, wherein a silicon substrate having a resistivity of 1000 Ω·cm or more is used as the silicon substrate. [F]: A silicon substrate for a quantum computer, comprising: Silicon substrate; The Si epitaxial layer is an epitaxial layer located on the silicon substrate and has 28 Si and 30 The total content of Si in the entire silicon of the epitaxial layer is 99.9% or more; The SiO2 layer is located on the Si epitaxial layer and has 28 Si and 30 The total content of Si in the entire silicon of the SiO2 layer is 99.9% or more; and The Si epitaxial layer is an epitaxial layer located on the SiO2 layer and has 28 Si and30 The total content of Si in the entire silicon of the epitaxial layer is 99.9% or more. [G]: The silicon substrate for a quantum computer as described in [F] above, wherein the SiO2 layer is a delta-doped layer of oxygen (O). [H]: The silicon substrate for a quantum computer as described in [F] above, wherein the SiO2 layer is a buried oxide film (BOX) layer in the SOI structure. [7]: A silicon substrate for a quantum computer, comprising: Silicon substrate; 28 A Si epitaxial layer, which is located on the silicon substrate; 28 The SiO2 layer is located in the 28 On the Si epitaxial layer; and 28 Si epitaxial layer, which is located in the 28 On the SiO2 layer. [8]: The silicon substrate for quantum computer as described in [7] above, wherein the 28 The SiO2 layer is a delta-doped layer of oxygen (O). [9]: The silicon substrate for quantum computer as described in [7] above, wherein the 28 The SiO2 layer is the buried oxide film (BOX) layer in the SOI structure.

[10] : A semiconductor device characterized by comprising a component on a silicon substrate for a quantum computer described in [F], [G], [H], [7], [8] or [9].

[0099] The present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any device having substantially the same configuration and exhibiting the same function as the technical concept described in the claims of the present invention is included in the technical scope of the present invention.

Claims

1. A method for manufacturing a silicon substrate for a quantum computer, characterized in that: The following steps are involved: By using 28 Si and 30 A step of epitaxially growing a Si epitaxial layer on a silicon substrate using a Si source gas in which the total content of Si in the entire silicon contained in the silicon-based raw material gas is 99.9% or more as the silicon-based raw material gas; a step of oxidizing the surface of the Si epitaxial layer to form a delta-doped layer of oxygen (O); and By using 28 Si and 30 A step of forming a Si epitaxial layer by epitaxially growing the δ-doped layer using a Si source gas in which the total content of Si in the entire silicon contained in the silicon-based raw material gas is 99.9% or more.

2. The method for manufacturing a silicon substrate for a quantum computer according to claim 1, characterized in that: Monosilane gas was used as the Si source gas.

3. The method for manufacturing a silicon substrate for a quantum computer according to claim 1, characterized in that: The steps of forming the oxygen (O) delta-doped layer and forming the Si epitaxial layer on the delta-doped layer are repeated to form a plurality of pairs of the delta-doped layer and the Si epitaxial layer located on the delta-doped layer.

4. The method for manufacturing a silicon substrate for a quantum computer according to claim 3, characterized in that: The thickness of the Si epitaxial layer of the outermost layer of the silicon substrate for a quantum computer is made thicker than the thickness of the Si epitaxial layer other than the Si epitaxial layer of the outermost layer.

5. The method for manufacturing a silicon substrate for a quantum computer according to claim 4, characterized in that: By subjecting the silicon substrate for a quantum computer to a heat treatment, an SOI structure is produced in which the plurality of delta-doped layers are integrated.

6. A method for manufacturing a silicon substrate for a quantum computer, characterized in that: The following steps are involved: use 28 Si source gas is used as silicon raw material gas to perform epitaxial growth on the silicon substrate, thereby forming 28 Si epitaxial layer step; Regarding the 28 The step of oxidizing the surface of the Si epitaxial layer to form a delta-doped layer of oxygen (O); as well as By using 28 Si source gas is epitaxially grown on the delta-doped layer to form 28 Si epitaxial layer step.

7. The method for manufacturing a silicon substrate for a quantum computer according to claim 6, characterized in that: use 28 Si monosilane gas as the 28 Si source gas.

8. The method for manufacturing a silicon substrate for a quantum computer according to claim 6, characterized in that: Repeat the steps of forming the oxygen (O) delta-doped layer and forming the 28 The step of forming a Si epitaxial layer to form a plurality of pairs of the δ-doped layers and the δ-doped layers located on the δ-doped layers 28 Si epitaxial layer.

9. The method for manufacturing a silicon substrate for a quantum computer according to claim 8, characterized in that: The outermost layer of the silicon substrate for the quantum computer 28 The thickness of the Si epitaxial layer is greater than that of the outermost layer. 28 Other than Si epitaxial layer 28 The thickness of the Si epitaxial layer is thicker.

10. The method for manufacturing a silicon substrate for a quantum computer according to claim 9, characterized in that: By subjecting the silicon substrate for a quantum computer to a heat treatment, an SOI structure is produced in which the plurality of delta-doped layers are integrated.

11. The method for producing a silicon substrate for a quantum computer according to any one of claims 1 to 10, characterized in that: As the silicon substrate, a silicon substrate having a resistivity of 1000 Ω·cm or more is used.

12. A silicon substrate for a quantum computer, characterized in that: have: Silicon substrate; The Si epitaxial layer is an epitaxial layer located on the silicon substrate and has 28 Si and 30 The total content of Si in the entire silicon of the epitaxial layer is 99.9% or more; The SiO2 layer is located on the Si epitaxial layer and has 28 Si and 30 The total content of Si in the entire silicon of the SiO2 layer is 99.9% or more; and The Si epitaxial layer is an epitaxial layer located on the SiO2 layer and has 28 Si and 30 The total content of Si in the entire silicon of the epitaxial layer is 99.9% or more.

13. The silicon substrate for quantum computer according to claim 12, characterized in that: The SiO2 layer is a delta-doped layer of oxygen (O).

14. The silicon substrate for quantum computer according to claim 12, characterized in that: The SiO2 layer is a buried oxide film (BOX) layer in the SOI structure.

15. A silicon substrate for a quantum computer, characterized in that: have: Silicon substrate; 28 A Si epitaxial layer, which is located on the silicon substrate; 28 The SiO2 layer is located in the 28 On the Si epitaxial layer; and 28 Si epitaxial layer, which is located in the 28 On the SiO2 layer.

16. The silicon substrate for quantum computer according to claim 15, characterized in that: Said 28 The SiO2 layer is a delta-doped layer of oxygen (O).

17. The silicon substrate for quantum computer according to claim 15, characterized in that: Said 28 The SiO2 layer is the buried oxide film (BOX) layer in the SOI structure.

18. A semiconductor device, characterized in that: A device is provided on the silicon substrate for a quantum computer according to any one of claims 12 to 17.

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