WO2025142960A1 - Method for producing graphene - Google Patents

Abstract

Provided is a method for producing graphene, in which heat bias inside a reaction vessel can be suppressed.　Provided is a method for producing graphene using a thermal CVD device, wherein the thermal CVD device has a cylindrical reaction vessel inside of which a base material for graphene production is accommodated, a gas supply unit that is connected to the reaction vessel and supplies a hydrocarbon-containing raw material gas toward the base material, a gas discharge unit that discharges gas, a heater that covers the periphery of a region including a region in which the base material is accommodated and that heats the inside of the reaction vessel, and a shielding member that is disposed inside the reaction vessel and intercepts the movement of heat. The shielding member is disposed at least between the gas supply unit and the substrate and between the substrate and the gas discharge unit, and the relationship of formula (x1) holds, where W is the flow rate of the raw material gas introduced from the gas supply unit, S is the internal cross-sectional area of the reaction vessel, and x is the inside diameter of the reaction vessel.　Formula (x1): W/S ≤ 54.97 × exp{–0.128 × (x – 4.0)}

Description

How graphene is produced

The present invention relates to a method for producing graphene using a thermal CVD (Chemical Vapor Deposition) device.

Graphene is a sheet-like substance in which carbon atoms are bonded to each other by ^sp2 bonds, and graphite is made up of stacked graphene sheets. In graphene, a hexagonal lattice structure (hexagonal mesh surface) is formed by carbon atoms and their bonds.

Patent Literature 1 describes a method for producing graphene, in which a surface of a substrate is oxidized to form an oxide layer, and a nanocarbon material layer (graphene layer) is formed on the surface of the oxide layer. More specifically, the method describes a method in which the substrate is placed in a reaction vessel, a gaseous carbon source is supplied into the reaction vessel, and the substrate in the reaction vessel is heated to form a nanocarbon material layer on the oxide layer formed on the substrate.
The method for forming the graphene layer described in Patent Document 1 corresponds to CVD.

JP 2021-178760 A

The present inventors have studied the production method described in Patent Document 1 and found that heat unevenness may occur inside the reaction vessel. When heat unevenness occurs inside the reaction vessel, problems such as graphene not being efficiently produced may occur.
Such a decrease in efficiency during graphene production can become more pronounced when the reaction vessel has a larger diameter.

The present invention was made in consideration of the above problems, and aims to provide a method for producing graphene that can suppress heat bias inside a reaction vessel.

After extensive research into the above problem, the inventors discovered that the heat bias can be suppressed by adjusting the gas flow rate so that a specific relationship is satisfied between the internal cross-sectional area, the inner diameter of the reaction vessel, and the flow rate of the raw material gas, and thus arrived at the present invention.

That is, the inventors discovered that the above problems can be solved by the following configuration.
[1] A method for producing graphene using a thermal CVD apparatus, comprising the steps of:
The thermal CVD apparatus is
A cylindrical reaction vessel in which a substrate for graphene production is housed;
a gas supply unit connected to the reaction vessel and configured to supply a raw material gas containing a hydrocarbon toward the base material accommodated inside the reaction vessel;
a gas exhaust part connected to the reaction vessel on the opposite side to the gas supply part side and configured to exhaust gas from inside the reaction vessel;
a heater that surrounds a region of the reaction vessel including a region in which the base material is accommodated and heats the inside of the reaction vessel;
a shielding member disposed inside the reaction vessel to block heat transfer inside the reaction vessel;
The shielding member is disposed at least between the gas supply unit and the substrate and between the substrate and the gas exhaust unit,
a flow rate of the raw material gas introduced from the gas supply unit is W, an internal cross-sectional area of the reaction vessel is S, and an inner diameter of the reaction vessel is x, satisfying a relationship of a formula (x1) described below.
[2] A first shielding member, a second shielding member, a third shielding member and a fourth shielding member are arranged in this order in the reaction vessel from the gas supply part side to the gas discharge part side of the reaction vessel as the shielding members,
the second shielding member and the third shielding member are disposed in an area of the reaction vessel covered by the heater,
The graphene production method according to [1], wherein the first shielding member and the fourth shielding member are disposed in an area of the reaction vessel that is not covered by the heater.
[3] The first shielding member, the second shielding member, the third shielding member, and the fourth shielding member each include one or more shielding plates,
Each of the shielding plates has one or more holes;
The method for producing graphene according to [2], wherein an opening ratio of each of the shielding plates is 0.1 to 40% with respect to an internal cross-sectional area of the reaction vessel.
[4] The first shielding member, the second shielding member, the third shielding member and the fourth shielding member each include two or more shielding plates arranged at a constant interval d1,
The graphene production method according to [3], wherein a ratio D12/d1 of a distance D12 between the first shielding member and the second shielding member to the interval d1, and a ratio D34/d1 of a distance D34 between the third shielding member and the fourth shielding member to the interval d1 are each 0.03 to 52.88.
[5] The length of the first shielding member is L1,
The length of the second shielding member is L2,
The length of the third shielding member is L3,
When the length of the fourth shielding member is L4,
a ratio D12/L1 of the distance D12 to the length L1 and a ratio D12/L2 of the distance D12 to the length L2 are each between 0.01 and 23.27;
The graphene production method according to [4], wherein a ratio D34/L3 of the distance D34 to the length L3 and a ratio D34/L4 of the distance D34 to the length L4 are each 0.01 to 23.27.
[6] When a distance from an end of the area covered by the heater on the gas supply part side to the first shielding member is a distance D1H, a value X1H calculated by the following formula (1) using the distance D12 is 0.01 or more,
The graphene production method according to [4] or [5], wherein when a distance from an end of a region covered by the heater on the gas discharge part side to the fourth shielding member is a distance D4H, a value X4H calculated by the following formula (2) using the distance D34 is 0.01 or more.
Formula (1) X1H=(D12-D1H)/D12
Formula (2) X4H = (D34 - D4H) / D34
[7] The method for producing graphene according to [6], wherein the value X1H and the value X4H are 0.60 to 1.00.
[8] An aperture ratio of the shielding plate in the first shielding member is larger than an aperture ratio of the shielding plate in the second shielding member,
The method for producing graphene according to any one of [3] to [7], wherein an aperture ratio of the shielding plate in the fourth shielding member is larger than an aperture ratio of the shielding plate in the third shielding member.
[9] The method for producing graphene according to any one of [3] to [8], wherein a product of the aperture ratios of the shielding plates constituting the first shielding member and the second shielding member and a product of the aperture ratios of the shielding plates constituting the third shielding member and the fourth shielding member are each 0.0009 to 0.0700%.
[10] The second shielding member includes two or more of the shielding plates, and the second shielding member includes the shielding plates having different opening ratios,
The method for producing graphene according to any one of [3] to [9], wherein the third shielding member includes two or more of the shielding plates, and the second shielding member includes the shielding plates having different aperture ratios.
[11] The second shielding member includes two or more shielding plates, and the aperture ratio of the shielding plate of the second shielding member arranged closest to the third shielding member is smaller than the aperture ratio of the shielding plate of the second shielding member arranged closest to the first shielding member,
The method for producing graphene according to any one of [3] to [10], wherein the third shielding member includes two or more shielding plates, and the aperture ratio of the shielding plate of the third shielding member arranged closest to the second shielding member is smaller than the aperture ratio of the shielding plate of the third shielding member arranged closest to the fourth shielding member.
[12] The first shielding member includes two or more shielding plates, and the aperture ratio of the shielding plate of the first shielding member arranged closest to the gas supply unit is smaller than the aperture ratio of the shielding plate of the first shielding member arranged closest to the second shielding member,
The method for producing graphene according to any one of [3] to [11], wherein the fourth shielding member includes two or more shielding plates, and an aperture ratio of the shielding plate of the fourth shielding member arranged closest to the gas discharge portion side is smaller than the aperture ratio of the shielding plate of the fourth shielding member arranged closest to the third shielding member side.
[13] The method for producing graphene according to any one of [3] to [12], wherein the shielding plate contains at least one selected from the group consisting of silicon oxide, silicon nitride, graphite, aluminum oxide, aluminum nitride, tantalum oxide, tantalum carbide, niobium oxide, niobium carbide, and molybdenum oxide.
[14] The method for producing graphene according to any one of [3] to [13], wherein the second shielding member and the third shielding member are made of metal.
[15] The method for producing graphene according to any one of [1] to [14], wherein a value obtained by dividing a temperature measured at the following first position by a temperature measured at the following second position is 0.62 or more.
First position: the axial position of the reaction vessel on the surface of the first shielding member facing the substrate. Second position: the axial position of the reaction vessel at the center of the substrate. Note that the units of the temperature measured at the first position and the temperature measured at the second position are °C.
[16] The graphene production method according to any one of [1] to [15], wherein the reaction vessel has an inner diameter of 12.7 to 38.1 cm.
[17] The graphene production method according to any one of [1] to [16], wherein the reaction vessel has an inner diameter of 15.24 to 35.56 cm.
[18] The graphene production method according to any one of [1] to [17], wherein the reaction vessel has an inner diameter of 20.32 to 30.48 cm.
[19] The method for producing graphene according to any one of [1] to [18], wherein the reaction vessel contains silicon dioxide.
[20] The method for producing graphene according to any one of [1] to [19], wherein the base material including a metal film including at least one selected from the group consisting of copper, nickel, and iron is placed in the reaction vessel, a raw material gas including a hydrocarbon is supplied from the gas supply unit, and the inside of the reaction vessel is heated to 900 to 1,100° C. by the heater, to form a graphene layer on the metal film.

The present invention provides a method for producing graphene that can suppress heat bias inside a reaction vessel.

FIG. 1 is a schematic cross-sectional view of one embodiment of a thermal CVD apparatus used in the graphene production method of the present invention. FIG. 2 is a schematic cross-sectional view of a first shielding member 11. 2 is a schematic diagram of the first shielding member 11 as viewed from the gas supply unit 22 side. FIG. 2 is a schematic cross-sectional view of a shielding plate of a first shielding member in a reaction chamber of a thermal CVD apparatus. FIG.

Below, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiment. Various modifications and substitutions can be made to the following embodiment without departing from the scope of the present invention.

The terms used in this specification have the following meanings:
A numerical range expressed using "to" means a range that includes the numerical values before and after "to" as the lower and upper limits.

In this specification, graphene includes not only single-layer graphene consisting of a single graphene sheet, but also multi-layer graphene consisting of stacked single-layer graphene sheets. The number of layers of the graphene sheets in the multi-layer graphene is preferably 2 to 10, and more preferably 2 to 5.
The graphene sheet is a sheet made of carbon atoms bonded together in a plane by ^sp2 bonds, and has a thickness equivalent to one carbon atom. In the graphene sheet, carbon atoms exist at each vertex of the hexagonal mesh plane.

The graphene production method of the present invention (hereinafter also referred to as "the present production method") is a production method for producing graphene using a thermal CVD apparatus.
The thermal CVD apparatus includes a gas supply unit connected to the reaction vessel and supplying a source gas containing a hydrocarbon toward the substrate housed inside the reaction vessel, and a gas discharge unit connected to the reaction vessel on the opposite side to the gas supply unit side and discharging gas from inside the reaction vessel. In addition, the thermal CVD apparatus used in the present manufacturing method includes a heater that covers the periphery of an area including the area in which the substrate is housed in the reaction vessel and heats the inside of the reaction vessel. The thermal CVD apparatus includes a cylindrical reaction vessel in which a substrate for graphene production is housed, and a gas supply unit connected to the reaction vessel and supplying a source gas containing a hydrocarbon toward the substrate housed inside the reaction vessel. The thermal CVD apparatus also includes a gas discharge unit connected to the reaction vessel on the opposite side to the gas supply unit side and discharging gas from inside the reaction vessel, a heater that covers the periphery of an area including the area in which the substrate is housed in the reaction vessel and heats the inside of the reaction vessel, and a shielding member that is disposed inside the reaction vessel and blocks heat transfer inside the reaction vessel. The shielding member is disposed at least between the gas supply unit and the base material, and between the base material and the gas discharge unit.
Furthermore, in the present production method, when the flow rate of the raw material gas introduced from the gas supply part is W, the internal cross-sectional area of the reaction vessel is S, and the inner diameter of the reaction vessel is x, the relationship of the following formula (x1) is satisfied.
Formula (x1) W/S ≦ 54.97×exp {-0.128×(x-4.0)}
In formula (x1), the unit of W is cm ³ /min, which represents the flow rate of gas per minute converted into a volume value at 1 atmospheric pressure and 0°C.
In formula (x1), the unit of S is ^cm2 .
In formula (x1), the unit of x is cm.

Below, we will explain this manufacturing method while providing a detailed explanation of the thermal CVD apparatus used in this manufacturing method. After explaining the thermal CVD apparatus used in this manufacturing method, we will explain this manufacturing method in detail.

<Thermal CVD equipment>
The thermal CVD apparatus used in this manufacturing method has a reaction vessel in which a substrate for graphene production is housed. The thermal CVD apparatus used in this manufacturing method further has a gas supply unit connected to the reaction vessel and supplying a raw material gas containing a hydrocarbon toward the substrate housed inside the reaction vessel, a gas discharge unit connected to the side of the reaction vessel opposite the gas supply unit side and discharging gas from inside the reaction vessel, and a gas discharge unit connected to the side of the reaction vessel opposite the gas supply unit side. In addition, the thermal CVD apparatus used in this manufacturing method has a heater that covers the periphery of an area including an area in which the substrate is housed in the reaction vessel and heats the inside of the reaction vessel.

Here, a shielding member for blocking heat transfer inside the reaction vessel is disposed within the reaction vessel, and is disposed at least between the gas supply unit and the base material, and between the base material and the gas discharge unit.
The thermal CVD apparatus used in this manufacturing method will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of one embodiment of a thermal CVD apparatus used in this production method.
The thermal CVD apparatus 100 has a cylindrical reaction vessel 10. A substrate S1 for producing graphene is placed inside the reaction vessel 10. The substrate S1 is placed on a boat B1.
A gas supply unit 22 is connected to one end of the reaction vessel 10, and a gas exhaust unit 24 is connected to the other end of the reaction vessel 10. A raw material gas containing a hydrocarbon is supplied from the gas supply unit 22 toward the substrate S1 through a pipe (not shown) connected to the gas supply unit 22 (see the open arrow in FIG. 1). The gas supplied from the gas supply unit 22 and used in the reaction in the reaction vessel 10 is exhausted from the gas exhaust unit 24 (see the filled arrow in FIG. 1).
Further, the reaction vessel 10 has a periphery of a region A2 including a region A1 in which the substrate S1 is accommodated, covered with a heater 26, and the inside of the reaction vessel 10 can be heated in the region A2 covered with the heater 26.

In the reaction vessel 10, a first shielding member 11, a second shielding member 12, a third shielding member 13, and a fourth shielding member 14 are arranged in this order from the gas supply unit 22 side.
In the thermal CVD apparatus 100, a source gas is supplied from the gas supply unit 22, the substrate S1 and the source gas are heated by the heater 26, and graphene is produced on the substrate S1 by thermal CVD.

In the thermal CVD apparatus 100, the second shielding member 12 and the third shielding member 13 are disposed in an area A2 of the reaction vessel 10 that is covered by the heater 26.
Specifically, the second shielding member 12 is disposed in the reaction vessel 10 on the side where the substrate S1 is disposed relative to the imaginary line VL1 indicating the end of the heater 26 on the gas supply unit 22 side in FIG.
On the other hand, the third shielding member 13 is disposed in the reaction vessel 10 on the side where the substrate S1 is disposed relative to the imaginary line VL2 indicating the end of the heater 26 on the gas discharge part 24 side in FIG.

In the thermal CVD apparatus 100, the first shielding member 11 and the fourth shielding member 14 are disposed in an area A3 of the reaction vessel 10 that is not covered by the heater 26.
Specifically, the first shielding member 11 is disposed in the reaction vessel 10 on the gas supply unit 22 side of the imaginary line VL1 indicating the end of the heater 26 in FIG.
On the other hand, the fourth shielding member 14 is disposed in the reaction vessel 10 on the gas discharge part 24 side of the imaginary line VL2 indicating the end of the heater 26 in FIG.

Each of the first shielding member 11, the second shielding member 12, the third shielding member 13, and the fourth shielding member 14 includes three shielding plates. The details of each shielding member will be described later.
1 has been described as using the first shielding member 11, the second shielding member 12, the third shielding member 13, and the fourth shielding member 14 as the shielding members, but in this manufacturing method, for example, the second shielding member 12 and the third shielding member 13 may be omitted. In another embodiment, the first shielding member 11 and the fourth shielding member 14 may be omitted.
Furthermore, it is sufficient that the shielding member is disposed at least between the gas supply section 22 and the substrate S1, and between the substrate S1 and the gas discharge section 24, and the shielding member may be disposed in a manner other than that shown in FIG. 1.

By using the thermal CVD apparatus 100 (the thermal CVD apparatus used in the present manufacturing method) and adjusting it so as to satisfy the relationship of the above formula (x1), it is possible to suppress uneven distribution of heat inside the reaction vessel 10.
Although the mechanism by which the present production method can suppress uneven distribution of heat inside the reaction vessel 10 is not entirely clear, the present inventors speculate as follows.

1, the shielding members are arranged at the above-mentioned positions in the reaction vessel 10. More specifically, the first shielding member 11 and the second shielding member 12 are arranged between the gas supply unit 22 and the substrate S1, and the third shielding member 13 and the fourth shielding member 14 are arranged between the substrate S1 and the gas exhaust unit 24. Each shielding member prevents heat from the heater 26 from transferring to the gas supply unit 22 side and the gas exhaust unit 24 side of the reaction vessel 10.
Here, when the raw material gas is supplied from the gas supply unit 22 so as to satisfy the relationship of the above formula (x1), the supply amount of the raw material gas becomes relatively small with respect to the inner diameter of the reaction vessel 10. In this case, the raw material gas supplied from the gas supply unit 22 is likely to be sufficiently heated by the heater 26 before being supplied toward the substrate S1. As a result, the raw material gas is preheated before being introduced toward the region A1 where the substrate S1 is placed, so that heat bias inside the reaction vessel 10 can be suppressed.

The details of the configuration of the thermal CVD apparatus 100 and the configuration that the thermal CVD apparatus 100 may have will be described below.
The thermal CVD apparatus used in this manufacturing method may be of an embodiment other than that shown in Fig. 1. That is, the components of the thermal CVD apparatus may be modified to the embodiments described below.

The reaction vessel 10 is cylindrical, and its inner diameter is, for example, 10 cm or more, preferably 12.7 cm or more, more preferably 15.24 cm or more, and even more preferably 20.32 cm or more. The inner diameter is, for example, 50 cm or less, and in order to further suppress heat bias inside the reaction vessel 10, it is preferably 38.1 cm or less, more preferably 35.56 cm or less, and even more preferably 30.48 cm or less.

The wall thickness of the reaction vessel 10 is, for example, preferably 1 to 50 mm, and more preferably 2 to 40 mm.
The length of the reaction vessel 10 is not particularly limited, but may be, for example, 20 m or less, and preferably 10 m or less. The length of the reaction vessel 10 may be, for example, 0.5 m or more, and preferably 1 m or more.

It is preferable that the reaction vessel 10 does not undergo deformation or the like due to heating by the heater 26 .
Examples of materials constituting the reaction vessel 10 include materials containing at least one selected from the group consisting of silicon oxide, silicon nitride, graphite, aluminum oxide, aluminum nitride, tantalum oxide, tantalum carbide, niobium oxide, niobium carbide, and molybdenum oxide.
More specifically, silicon oxide (quartz glass) is preferred.

The gas supply unit 22 is not particularly limited as long as it can supply a source gas containing a hydrocarbon and can control the supply amount of the source gas so as to satisfy the relationship shown in the above formula (x1). For example, the gas supply unit 22 is connected to a flow control valve and a gas supply source, and supplies the source gas from a gas storage unit while controlling the supply amount with the flow control valve.
Furthermore, the raw gas supplied from the gas supply unit 22 may be a mixed gas, as described below. When a mixed gas is supplied from the gas supply unit 22 as the raw gas, a gas mixing unit may be provided. The gas mixing unit mixes gases supplied from gas supply sources that supply the respective components constituting the mixed gas. When a mixed gas is supplied as the raw gas, a flow rate control valve is preferably provided between the gas mixing unit and the gas supply source.
The gas supply source may be, for example, a known gas cylinder.
As the flow rate adjusting valve, for example, a known mass flow controller can be used.
The source gas will be described in detail later.

A pressure gauge may be connected to the gas supply unit 22. The amount of the source gas supplied from the gas supply unit 22 may be controlled based on the pressure measured by the pressure gauge.
As the pressure gauge, a known pressure gauge can be applied depending on the desired pressure.

The gas exhaust part 24 is not particularly limited as long as it can exhaust gas from inside the reaction vessel 10. For example, the gas exhaust part 24 connects the reaction vessel 10 to the outside via a valve (e.g., a check valve and a pressure regulating valve).
The gas discharge section 24 may be connected to a known exhaust gas treatment means. Examples of the exhaust gas treatment means include a combustion type exhaust gas treatment device that combusts hydrocarbons and the like contained in the exhaust gas.

A pressure gauge may be connected to the gas discharge unit 24. The supply amount of the source gas supplied from the gas supply unit 22 may be controlled based on the pressure measured by the pressure gauge. Also, the opening degree of the pressure regulating valve may be adjusted based on the measured pressure.
As the pressure gauge, a known pressure gauge can be applied depending on the desired pressure.

In addition, a vacuum exhaust means may be connected to the gas exhaust section 24. A known vacuum pump may be used as the vacuum exhaust means connected to the gas exhaust section 24. When a vacuum exhaust means is connected to the gas exhaust section 24, the vacuum exhaust means and the gas exhaust section 24 may be connected via the valve, and the vacuum exhaust means may be connected to the outside.

The heater 26 covers the periphery of the region A2 including the region A1 in which the substrate S1 of the reaction vessel 10 is accommodated, and heats the inside of the reaction vessel 10. When the inside of the reaction vessel 10 is heated, the substrate S1 accommodated inside the reaction vessel 10 and the supplied raw material gas are heated, and graphene is formed on the substrate S1.
The heater 26 is preferably capable of heating the inside of the reaction vessel 10 to 900° C. or higher, more preferably to 950° C. or higher, and even more preferably to 1,000° C. or higher.
The upper limit of the heating temperature is not particularly limited, but may be, for example, 1,200° C. or lower.

The heater 26 is not particularly limited as long as it can heat the inside of the reaction vessel 10, but an example of the heater 26 is a heater composed of a heat source and a heat-resistant plate placed between the heat source and the reaction vessel 10. An example of the heat source is a heat source that generates heat by resistance heating. The heat-resistant plate is composed of, for example, aluminum oxide (alumina, etc.) fibers.

The first shielding member 11 and the second shielding member 12 prevent heat from the heater 26 from transferring to the gas supply part 22 side of the reaction vessel 10. In addition, the third shielding member 13 and the fourth shielding member 14 prevent heat from the heater 26 from transferring to the gas discharge part 24 side of the reaction vessel 10.
Hereinafter, the first shielding member 11 will be described as a representative shielding member.

The first shielding member 11 of the embodiment shown in FIG. 1 will be described in detail with reference to FIGS. 2A and 2B.
Fig. 2A shows a schematic cross-sectional view of the first shielding member 11. The first shielding member 11 shown in Fig. 2A includes three shielding plates 110a, 110b, and 110c. The three shielding plates 110a, 110b, and 110c are connected to each other by a connecting rod 112 and are arranged at a predetermined interval d1.
Fig. 2B is a schematic diagram of the first shielding member 11 shown in Fig. 1 as viewed from the gas supply unit 22 side in the left-right direction of the paper surface of Fig. 1. Note that Fig. 2B shows only the shielding plate 110a, which is disposed closest to the gas supply unit 22 side among the three shielding plates (shielding plates 110a, 110b, and 110c) constituting the first shielding member 11.
2B, the shielding plate 110a has seven holes, H1 to H7. The holes H1 to H6 are arranged at positions that are symmetrical with respect to the center of the circular shielding plate 110a, and the hole H7 is arranged at the center position of the circular shielding plate 110a.

The material constituting the shielding plate 110a preferably includes at least one selected from the group consisting of silicon oxide (e.g., quartz glass), silicon nitride, graphite, aluminum oxide, aluminum nitride, tantalum oxide, tantalum carbide, niobium oxide, niobium carbide, and molybdenum oxide. The material constituting the shielding plate 110a may be a metal. Examples of the metal include known metals, such as iron, niobium, and molybdenum. The metal may be an alloy, such as steel and stainless steel.
The thickness of the shielding plate 110a is not particularly limited, but is often 0.1 mm or more, preferably 0.5 mm or more, and is often 5.0 mm or less.

The size (e.g., diameter) of the shielding plate 110a is smaller than the size (e.g., diameter) of the cross section of the inside of the reaction vessel 10, since the shielding plate 110a is installed inside the reaction vessel 10. Therefore, as shown in FIG. 3, a gap C1 is formed between the shielding plate 110a and the inner wall surface of the reaction vessel 10.
When the reaction vessel 10 is cylindrical, the value obtained by subtracting the diameter of the shielding plate 110a from the inner diameter (diameter) of the reaction vessel 10 is preferably 0.1 cm or more, more preferably 0.3 cm or more. Also, the value is preferably 3.0 cm or less.

Here, the aperture ratio of the shielding plate 110a with respect to the internal cross-sectional area of the reaction vessel 10 is preferably 0.1% or more, more preferably 1% or more, even more preferably 5% or more, and particularly preferably 10% or more. Moreover, the aperture ratio is preferably 65% or less, more preferably 32% or less, and even more preferably 16% or less.
The opening ratio is defined as the ratio of the shaded area in Fig. 3 to the internal cross-sectional area of the reaction vessel 10. Fig. 3 is a schematic cross-sectional view of the portion of the shielding plate 110a of the first shielding member 11 in the reaction vessel 10 of the thermal CVD apparatus 100 shown in Fig. 1.
That is, when determining the aperture ratio, first, the area of the shielding plate 110a minus the holes (holes H1 to H7) is determined as the area of the shielding plate 110a. Next, the area of the shielding plate 110a is subtracted from the internal cross-sectional area of the reaction vessel 10, and the obtained value is divided by the internal cross-sectional area of the reaction vessel 10 and multiplied by 100 to determine the aperture ratio (unit: %).
The opening ratio corresponds to the ratio of the area of the portion not shielded by the shield plate 110a (the portion through which the source gas can pass) to the cross-sectional area inside the reaction vessel 10.

The aperture ratios of the shielding plates 110b and 110c are also obtained in a similar manner to the above procedure.
The preferred range of the aperture ratio of the shielding plates 110b and 110c is the same as the preferred range of the aperture ratio of the shielding plate 110a.

The aperture ratio of the shielding plate 110a can be adjusted by the number and size of the holes in the shielding plate 110a. For example, the aperture ratio can be adjusted by the size of holes H1 to H7 in the shielding plate 110a.

The configuration of the shielding plates 110b and 110c constituting the first shielding member 11 may be the same as or different from the shielding plate 110a.
For example, in the first shielding member 11, the aperture ratios of the shielding plates 110a, 110b, and 110c may be different from one another or may be the same as one another.

It is also preferable that the first shielding member 11 includes shielding plates 110a, 110b, and 110c with different aperture ratios. When the first shielding member 11 includes shielding plates with different aperture ratios, it is preferable that the aperture ratio of the shielding plate arranged closest to the gas supply section 22 is smaller than the aperture ratio of the shielding plate arranged closest to the second shielding member 12. In other words, when the first shielding member 11 includes shielding plates with different aperture ratios, it is preferable that the aperture ratio of shielding plate 110a is smaller than the aperture ratio of shielding plate 110c.

The product of the aperture ratios of the shielding plates constituting the first shielding member 11 is preferably 0.0005% or more, more preferably 0.0008% or more, and even more preferably 0.0010% or more. The product of the aperture ratios is preferably 80.0000% or less, more preferably 10.0000% or less, even more preferably 6.0000% or less, and particularly preferably 1.0000% or less.
Specifically, the product of the aperture ratios is obtained by multiplying the aperture ratio of the shielding plate 110a by the aperture ratio of the shielding plate 110b by the aperture ratio of the shielding plate 110c.

The shielding plate 110a may have a configuration other than that shown in Fig. 2B. For example, the arrangement of the holes, the number of the holes, the size of the holes, etc. can be changed as appropriate.
The shielding plates 110b and 110c may have the same configuration as the shielding plate 110a. The shielding plates 110a, 110b, and 110c may have the same configuration as each other, may have a partially similar configuration, or may have different configurations.
Furthermore, when the first shielding member 11 includes three or more shielding plates, the distances between adjacent shielding plates may be the same or different.

In FIG. 1, the first shielding member 11 is shown to have three shielding plates, but the first shielding member 11 may have only one shielding plate. When the first shielding member is composed of only one shielding plate, the product of the aperture ratios of the shielding plates is the aperture ratio of that shielding plate. The first shielding member may also have two or more shielding plates (e.g., 2 to 10, preferably 2 to 6).

The examples of the second shielding member 12, the third shielding member 13 and the fourth shielding member 14 are similar to the example of the first shielding member 11, and therefore description thereof will be omitted.
In particular, it is preferable that the aperture ratio of the shielding plates in the first shielding member 11 is greater than the aperture ratio of the shielding plates in the second shielding member 12, and that the aperture ratio of the shielding plates in the fourth shielding member 14 is greater than the aperture ratio of the shielding plates in the third shielding member 13. The aperture ratio of the shielding plates in the first shielding member 11 refers to the aperture ratio of the shielding plates when the first shielding member 11 includes only one shielding plate, and refers to the aperture ratio of the shielding plate having the smallest aperture ratio among the shielding plates constituting the first shielding member 11 when the first shielding member 11 includes two or more shielding plates.
The difference between the aperture ratio of the shielding plate in the first shielding member 11 and the aperture ratio of the shielding plate in the second shielding member 12 is preferably 0 to 12.4%.
The difference between the aperture ratio of the shielding plate in the fourth shielding member 14 and the aperture ratio of the shielding plate in the third shielding member 13 is preferably 0 to 12.4%.
In addition, in terms of further suppressing heat bias inside the reaction vessel 10, it is also preferable that the difference between the opening rate of the shielding plate in the first shielding member 11 and the opening rate of the shielding plate in the second shielding member 12 is 0 to 1%, and that the difference between the opening rate of the shielding plate in the fourth shielding member 14 and the opening rate of the shielding plate in the third shielding member 13 is 0 to 1%.

It is also preferable that the second shielding member 12 has two or more shielding plates, and the opening rate of the shielding plate of the second shielding member 12 arranged closest to the third shielding member 13 is smaller than the opening rate of the shielding plate of the second shielding member 12 arranged closest to the first shielding member 11.
It is also preferable that the third shielding member 13 has two or more shielding plates, and that the opening rate of the shielding plate of the third shielding member 13 arranged closest to the second shielding member 12 is smaller than the opening rate of the shielding plate of the third shielding member 13 arranged closest to the fourth shielding member 14.
The difference in aperture ratio between the shielding plate arranged closest to the third shielding member 13 in the second shielding member 12 and the shielding plate arranged closest to the first shielding member 11 is preferably 0 to 12.4%.
The difference in aperture ratio between the shielding plate arranged closest to the second shielding member 12 in the third shielding member 13 and the shielding plate arranged closest to the fourth shielding member 14 is preferably 0 to 12.4%.
It is also preferable that the fourth shielding member 14 has two or more shielding plates, and that the opening rate of the shielding plate of the fourth shielding member 14 arranged closest to the gas exhaust section 24 is smaller than the opening rate of the shielding plate of the fourth shielding member 14 arranged closest to the third shielding member 13.
The difference in the opening ratio between the shielding plate arranged closest to the gas discharge portion 24 side in the fourth shielding member 14 and the shielding plate arranged closest to the third shielding member 13 side is preferably 0 to 12.4%.

Moreover, the value obtained by multiplying the product of the aperture ratios of the shielding plates constituting the first shielding member 11 by the product of the aperture ratios of the shielding plates constituting the second shielding member 12 is preferably 0.0004% or more, more preferably 0.0006% or more, even more preferably 0.0008% or more, and particularly preferably 0.0010% or more. Moreover, the value obtained by multiplying the product of the aperture ratios is preferably 0.0700% or less, more preferably 0.0100% or less, and even more preferably 0.0020% or less.
Moreover, the value obtained by multiplying the product of the aperture ratios of the shielding plates constituting the third shielding member 13 by the product of the aperture ratios of the shielding plates constituting the fourth shielding member 14 is preferably 0.0004% or more, more preferably 0.0006% or more, even more preferably 0.0008% or more, and particularly preferably 0.0010% or more. Moreover, the value obtained by multiplying the product of the aperture ratios is preferably 0.0700% or less, more preferably 0.0100% or less, and even more preferably 0.0020% or less.

In FIG. 1, the distance between the first shielding member 11 and the second shielding member 12 is defined as a distance D12, and the distance between the third shielding member 13 and the fourth shielding member 14 is defined as a distance D34.
The distance D12 refers to the distance from the end of the first shielding member 11 closest to the second shielding member 12 to the end of the second shielding member 12 closest to the first shielding member 11. Similarly, the distance D34 refers to the distance from the end of the third shielding member 13 closest to the fourth shielding member 14 to the end of the fourth shielding member 14 closest to the third shielding member 13.
Also, consider the case where the first shielding member 11, the second shielding member 12, the third shielding member 13 and the fourth shielding member 14 are each shielding members formed by two or more shielding plates arranged at a certain interval d1 (see Figure 2A).
In this case, the ratio D12/d1 of the distance D12 to the interval d1 is preferably 0.03 or more, more preferably 1.2 or more, and even more preferably 2.7 or more, in that the raw material gas can be retained longer between the first shielding member 11 and the second shielding member 12 to be preheated and the heat bias in the reaction vessel 10 can be further suppressed. The ratio D12/d1 is preferably 52.88 or less, more preferably 23.50 or less, and even more preferably 3.8 or less, in that the raw material gas can be retained longer between the shielding plates to be preheated and the heat bias in the reaction vessel 10 can be further suppressed.
In addition, in this case, the ratio D34/d1 of the distance D34 to the interval d1 is preferably 0.03 or more, more preferably 1.2 or more, and even more preferably 2.7 or more, in that the gas is allowed to remain longer between the third shielding member 11 and the fourth shielding member 12 for heating, and the heat bias in the reaction vessel 10 can be further suppressed. The ratio D34/d1 is preferably 52.88 or less, more preferably 23.50 or less, and even more preferably 3.8 or less, in that the gas is allowed to remain longer between the shielding plates for heating, and the heat bias in the reaction vessel 10 can be further suppressed.

1, the length of the first shielding member 11 is L1, the length of the second shielding member 12 is L2, the length of the third shielding member 13 is L3, and the length of the fourth shielding member 14 is L4. The length of each of the shielding members refers to the length from one end to the other end of the shielding member.
In this case, the ratio D12/L1 of the distance D12 to the length L1 and the ratio D12/L2 of the distance D12 to the length L2 are each preferably 0.01 or more, more preferably 0.43 or more, and even more preferably 1.00 or more. Moreover, the ratios (the ratio D12/L1 and the ratio D12/L2) are each preferably 23.27 or less, more preferably 10.34 or less, and even more preferably 1.39 or less.
In this case, the ratio D34/L3 of the distance D34 to the length L3 and the ratio D34/L4 of the distance D34 to the length L4 are each preferably 0.01 or more, more preferably 0.43 or more, and even more preferably 1.00 or more. Moreover, the ratios (D34/L3 and D34/L4) are each preferably 23.27 or less, more preferably 10.34 or less, and even more preferably 1.39 or less.

1, the distance from the end (imaginary line VL1) of the region A2 where the reaction vessel 10 is covered by the heater 26 on the gas supply unit 22 side to the first shielding member 11 is defined as a distance D1H. Also, the distance from the end (imaginary line VL2) of the region A2 where the reaction vessel 10 is covered by the heater 26 on the gas discharge unit 24 side to the fourth shielding member 14 is defined as a distance D4H.
In this case, it is preferable that the value X1H calculated by the following formula (1) is 0.01 or more.
In addition, it is preferable that the value X4H calculated by the following formula (2) is 0.01 or more. When the values X1H and X4H are each in the above range, the uneven distribution of heat in the reaction vessel 10 is further suppressed.
Formula (1) X1H=(D12-D1H)/D12
Formula (2) X4H = (D34 - D4H) / D34

The value X1H indicates the ratio of the length of the area of the distance D12 that is not covered by the heater 26 to the distance D12. Similarly, the value X4H indicates the ratio of the length of the area of the distance D34 that is not covered by the heater 26 to the distance D34.
If the value X1H is 1.00, this indicates that the end of the heater 26 on the gas supply unit 22 side and the end of the first shielding member 11 on the second shielding member 12 side are aligned.
Similarly, if the value X4H is 1.00, this indicates that the end of the heater 26 on the gas discharge portion 24 side and the end of the fourth shielding member 14 on the third shielding member 13 side are aligned.
The value X1H is more preferably 0.60 or more, and even more preferably 0.80 or more, in that uneven distribution of heat within the reaction vessel 10 is further suppressed.
The value X4H is more preferably 0.60 or more, and even more preferably 0.80 or more, in that uneven distribution of heat within the reaction vessel 10 is further suppressed.
The maximum values of the above values X1H and X4H are both 1.00.

In addition, when the second shielding member 12 and the third shielding member 13 are omitted, each of the distances D1H and D4H is preferably 50 cm or less, and more preferably 15 cm or less. Also, each of the distances D1H and D4H may be 0 cm.
When the second shielding member 12 and the third shielding member 13 are omitted, it is preferable that the first shielding member 11 is disposed closer to the gas supply section 22 than the virtual line VL1. Also, when the second shielding member 12 and the third shielding member 13 are omitted, it is preferable that the fourth shielding member 14 is disposed closer to the gas discharge section 24 than the virtual line VL2.

When the second shielding member 12 and the third shielding member 13 are omitted, the product of the aperture ratios of the shielding plates constituting the first shielding member 11 is preferably 0.0004% or more, more preferably 0.0006% or more, even more preferably 0.0008% or more, and particularly preferably 0.0010% or more. The value obtained by multiplying the product of the aperture ratios is preferably 0.0700% or less, more preferably 0.0100% or less, and even more preferably 0.0020% or less.
When the second shielding member 12 and the third shielding member 13 are omitted, the product of the aperture ratios of the shielding plates constituting the fourth shielding member 14 is preferably 0.0004% or more, more preferably 0.0006% or more, even more preferably 0.0008% or more, and particularly preferably 0.0010% or more. The value obtained by multiplying the product of the aperture ratios is preferably 0.0700% or less, more preferably 0.0100% or less, and even more preferably 0.0020% or less.

The boat B1 is disposed to hold the substrate S1. Usually, the boat B1 is carried into the reaction vessel 10 with the substrate S1 disposed on the boat B1.
The upper surface of the boat B1 on which the substrate S1 is placed may be flat, or may be provided with rails, claws, and the like for fixing the substrate S1.
It is preferable that the boat B1 does not deform due to heating by the heater 26. Examples of materials constituting the boat B1 include the same materials as those constituting the shielding plate.

The boat B1 in the embodiment shown in Fig. 1 holds one substrate S1, but the boat B1 may hold two or more substrates S1. In that case, the substrates S1 may be arranged in the boat B1 in the left-right direction of the paper surface of Fig. 1, in the front-rear direction of the paper surface, or in the up-down direction of the paper surface. Among them, an embodiment in which the substrates S1 are arranged in the up-down direction of the paper surface is preferable from the viewpoint of facilitating uniform supply of the raw material gas.
Note that the boat B1 may be omitted if unnecessary when producing graphene on the substrate S1 using the thermal CVD apparatus 100. Furthermore, the boat B1 may be replaced with a holder or the like on which the substrate S1 can be placed.

<Graphene manufacturing method>
The graphene production method of the present invention (the present production method) uses the thermal CVD apparatus (for example, the thermal CVD apparatus 100 shown in FIG. 1 ) used in the present production method described above.
Specifically, a raw material gas containing a hydrocarbon is supplied from the gas supply unit 22 to the substrate S1 accommodated in the reaction vessel 10, and the raw material gas and the substrate S1 in the reaction vessel 10 are heated by the heater 26, thereby forming graphene on the substrate S1.
As described above, in this manufacturing method, a thermal CVD apparatus other than that shown in FIG. 1 may be used.
The supply amount of the source gas is adjusted so as to satisfy the relationship of the above-mentioned formula (x1).

The substrate S1 preferably has a metal film. The metal film is preferably disposed on the surface of the substrate S1.
The metal film is preferably a metal film containing at least one selected from the group consisting of copper, nickel and iron, more preferably a metal film containing copper or nickel, and even more preferably a metal film containing copper. The metal film may be a simple metal or an alloy containing the metal.
The metal film preferably has a surface that matches the lattice constant of graphene exposed. Specifically, the (111) surface of copper and the (111) surface of nickel are preferably exposed. It is more preferable that the metal film has only the surface with the above Miller indices exposed.

The substrate S1 preferably has an oxide layer as an undercoat film for the metal film.
The oxide layer is preferably an oxide layer having a lattice constant that matches the lattice constant of the metal film. For example, such an oxide layer may be an oxide film containing one or more elements selected from the group consisting of magnesium, aluminum, titanium, and lanthanum, and an oxide film containing magnesium or aluminum is preferred. Preferred examples of the oxide film include MgO (magnesium oxide), α-Al ₂ O ₃ (alumina), LaAlO ₃ , and TiO ₂ , and MgO or α-Al ₂ O ₃ is preferred.

One embodiment of the substrate S1 including an oxide layer and a metal film is a substrate made of the material of the oxide layer and a metal film formed thereon.
In addition, one embodiment of the substrate S1 including an oxide layer and a metal film includes a substrate having the oxide layer and the metal film formed in this order. Examples of materials constituting the substrate include materials including SiO ₂ (quartz). It is also preferable that the substrate has a small linear thermal expansion coefficient.

The source gas contains a hydrocarbon, and may contain at least one of an inert gas and a reducing gas in addition to the hydrocarbon.
Examples of the hydrocarbon include methane, ethane, ethylene, acetylene, propane, propylene, butane, butadiene, pentane, pentene, cyclopentadiene, hexane, cyclohexane, benzene, and toluene. These may be used alone or in combination of two or more.
Examples of inert gases include nitrogen gas, helium gas, neon gas, argon gas, and krypton gas. These may be used alone or in combination of two or more.
An example of the reducing gas is hydrogen gas.

Consider the case where the source gas contains a hydrocarbon, an inert gas, and a reducing gas.
In the above case, the content of the hydrocarbon is preferably 0.00001% by volume or more, more preferably 0.0001% by volume or more, based on the total volume of the raw material gas, and the content of the hydrocarbon is preferably 0.1% by volume or less, more preferably 0.01% by volume or less.
In the above case, the content of the inert gas is preferably 90% by volume or more, more preferably 95% by volume or more, and even more preferably 98% by volume or more, based on the total volume of the raw material gas. The content of the inert gas is often 99.9% by volume or less.
In the above case, the content of the reducing gas is preferably 0.01% by volume or more, more preferably 0.1% by volume or more, based on the total volume of the raw material gas, and is preferably 5% by volume or less, more preferably 2% by volume or less.

As described above, the supply amount of the raw material gas is adjusted so as to satisfy the relationship of the following formula (x1).
Specifically, when the flow rate of the raw material gas introduced from the gas supply unit 22 is W, the internal cross-sectional area of the reaction vessel 10 is S, and the inner diameter (diameter) of the reaction vessel 10 is x, the supply amount of the raw material gas satisfies the relationship of the following formula (x1).
Formula (x1) W/S ≦ 54.97×exp {-0.128×(x-4.0)}
In formula (x1), the unit of W is cm ³ /min, which represents the flow rate of gas per minute converted into a volume value at 1 atmospheric pressure and 0°C.
In formula (x1), the unit of S is ^cm2 .
In formula (x1), the unit of x is cm.
The value obtained by dividing the value on the left side of the formula (x1) by the value on the right side is preferably 0.01 or more, more preferably 0.1 or more, even more preferably 0.3 or more, and particularly preferably 0.5 or more. The value is 1 or less, and preferably 0.97 or less.

The heating temperature inside the reaction vessel 10 by the heater 26 is preferably 900° C. or higher, more preferably 950° C. or higher, and even more preferably 1,000° C. or higher. The heating temperature inside the reaction vessel 10 by the heater 26 is preferably 1,200° C. or lower, more preferably 1,150° C. or lower, and even more preferably 1,100° C. or lower.
The heating temperature inside the reaction vessel 10 can be measured, for example, by inserting a thermocouple into the boat B1 and the substrate S1.
The heating time of the inside of the reaction vessel 10 by the heater 26 is preferably 5 minutes or more, more preferably 10 minutes or more, and is preferably 120 minutes or less, more preferably 60 minutes or less.

The heating inside the reaction vessel 10 by the heater 26 may be divided into a plurality of regions, and the heating temperature of each region may be controlled to a different temperature.
For example, in the embodiment shown in Figure 1, region A2 is divided into region A2a from the virtual line VL1 to the end of the second shielding member 12 on the substrate S1 side, region A2b from the end of the second shielding member 12 on the substrate S1 side to the end of the third shielding member 13 on the substrate S1 side, and region A2c from the end of the third shielding member 13 on the substrate S1 side to the virtual line VL2.
As described above, when the region A2 is divided into the regions A2a, A2b, and A2c, the regions A2a, A2b, and A2c may be controlled to different temperatures. For example, the region A2b is preferably controlled to the range described for the heating temperature inside the reaction vessel 10 by the heater 26, and the heating temperatures of the regions A2a and A2c are preferably controlled to a temperature 180 to 280° C. (more preferably 200 to 260° C.) higher than the heating temperature of the region A2b.

It is also preferable that the value obtained by dividing the temperature (° C.) measured at the first position described below by the temperature (° C.) measured at the second position described below is 0.62 or more.
First position: the axial position of the reaction vessel 10 on the surface of the first shielding member 11 facing the substrate S1. Second position: the axial position of the reaction vessel 10 at the center of the substrate S1. Note that the axial direction of the reaction vessel 10 refers to the longitudinal direction of the reaction vessel 10 (the left-right direction on the paper in Figure 1).
An example of a method for measuring the temperatures at the first and second positions is to place known thermocouples at the positions and measure the temperatures.
The above value is more preferably 0.9 or more, and is often 1.0 or less.
As a method for adjusting the temperature difference, for example, the area A2 may be divided into the areas A2a, A2b, and A2c, and each area may be controlled to a different temperature. The preferred temperatures are as described above.

It is also preferable that the value obtained by dividing the temperature (° C.) measured at the third position described below by the temperature (° C.) measured at the second position described above is 0.62 or more.
Third position: Axial position of the reaction vessel 10 on the surface of the fourth shielding member 14 facing the substrate S1. Methods for measuring the temperature at the third position include methods similar to those for measuring the temperature at the first and second positions described above.
The above value is more preferably 0.9 or more, and is often 1.0 or less.
As a method for adjusting the temperature difference, for example, the area A2 may be divided into the areas A2a, A2b, and A2c, and each area may be controlled to a different temperature. The preferred temperatures are as described above.

After graphene is formed on the substrate S1 by the above procedure, a procedure of cooling the inside of the reaction vessel 10 may be carried out.
When cooling the inside of the reaction vessel 10, the gas supplied from the gas supply unit 22 may or may not contain a hydrocarbon.
The cooling may be performed by removing the heater 26 from the reaction vessel 10 and air-cooling the reaction vessel 10, or by furnace-cooling the reaction vessel 10 with the heater 26 still attached.

In the graphene manufacturing method of the present invention, the thermal CVD apparatus 100 used in the manufacturing method described above is used, a source gas containing a hydrocarbon is supplied from the gas supply unit 22 to the substrate S1 contained in the reaction vessel 10, and the source gas and substrate S1 in the reaction vessel 10 are heated by the heater 26 to form graphene on the substrate S1, but other steps may also be included.

The other steps include placing the first shielding member 11, the second shielding member 12, the third shielding member 13 and the fourth shielding member 14, as well as the boat B1 and the substrate S1, in the reaction vessel 10 before graphene formation.

Another example of the other procedure is a procedure in which, before the formation of graphene, a gas containing a reducing gas but not containing a hydrocarbon is supplied from the gas supply unit 22 to the substrate S1 contained in the reaction vessel 10, and the inside of the reaction vessel 10 is heated by the heater 26. By carrying out the procedure, the surface of the substrate S1 is reduced, making it easier to form graphene.
The gas supplied in the above steps preferably contains the above-mentioned inert gas in addition to the reducing gas.
The heating temperature by the heater 26 in the above procedure can be appropriately adjusted depending on the material contained in the base material S1, but may be, for example, 300 to 1,200°C, and preferably 500 to 1,100°C.
When carrying out the above procedure, it is also preferable to supply a gas containing a reducing gas from the gas supply unit 22, and then supply only an inert gas from the gas supply unit 22 to replace the atmosphere in the reaction vessel 10 with the inert gas, and then supply a raw material gas containing a hydrocarbon to start the formation of graphene.

<Application>
The graphene formed on the substrate S1 can be used for various applications.
For example, the laminate can be used in an electromagnetic wave detection element, an electromagnetic wave sensor, an electronic device, and a structure. In particular, a laminate having a graphene single film with excellent SPP propagation characteristics can be preferably used as a detection element, an amplification element, and an oscillation element of a wideband electromagnetic wave.

The above-mentioned elements and the like can be manufactured by using graphene formed on the substrate S1 by a known method. For example, the formed graphene can be processed into a desired shape by applying photolithography and electron beam lithography.
In addition, the formed graphene can be used as an element by connecting desired electrodes, etc., using a known semiconductor manufacturing process.

The present invention will be described in further detail below with reference to examples.
The materials, amounts, ratios, processing contents, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following examples.
Examples 1 to 4 are working examples, and Examples 5 to 8 are comparative examples.

<Example 1>
The fourth shielding member 14, the third shielding member 13, the boat B1 and the substrate S1, the second shielding member 12, and the first shielding member 11 were inserted in this order into a reaction vessel 10 made of quartz glass and having a length of 170 cm and an inner diameter of 14 cm. The center position of the substrate S1 was adjusted so as to coincide with the center position of the reaction vessel 10 in the axial direction.
Next, a gas supply unit 22 and a gas discharge unit 24 were connected to both ends of the reaction vessel 10. A gas mixing unit (not shown) was connected to the gas supply unit 22. An argon gas cylinder as an argon gas supply source, a hydrogen gas cylinder as a hydrogen gas supply source, and a methane gas cylinder as a hydrocarbon supply source were connected to the gas mixing unit via mass flow controllers (none of which are shown).

The heater 26 was disposed in the reaction vessel 10 so as to cover the periphery of the region A2 including the region A1 in which the substrate S1 was accommodated. More specifically, the heater 26 was disposed so as to cover a region of 52.5 cm on both sides from the central position in the axial direction of the reaction vessel 10.
The first shielding member 11, the second shielding member 12, the third shielding member 13 and the fourth shielding member 14 were each composed of three shielding plates, and the aperture ratio of each of the shielding plates was 16%.
The positional relationship of each shielding member was adjusted so that the positions would yield the calculated values shown in Table 1 below.

In addition, in order to monitor the temperature of the inner wall surface of the reaction vessel 10 at each position, a thermocouple (not shown) was inserted into the reaction vessel 10. Specifically, the thermocouple was positioned so that the temperature measuring parts of the thermocouple were located at the center position of the substrate S1 and at positions 35 cm on both sides of the center position of the substrate S1 in the axial direction of the reaction vessel 10.
That is, the central position of the substrate S1 was set as the origin, and thermocouples were placed at positions of -35 cm, 0 cm, and 35 cm in the axial direction of the reaction vessel 10.

In order to calculate the heat distribution in the reaction vessel 10 by thermal fluid simulation, a model was created in which each component was placed in the reaction vessel 10. In this model, argon gas was supplied at the flow rate shown in the table below, and the output was adjusted so that the surface temperature of the heater 26 was 1,050° C., and the simulation was performed until a steady state was reached.
The maximum temperature difference in the temperature distribution when the steady state was reached was used as an index of heat bias. Note that the above temperature distribution is a temperature distribution in a plane parallel to the axial direction of the reaction vessel 10 and perpendicular to the surface of the substrate S1.

<Examples 2 to 8>
An index of heat distribution in the reaction vessel 10 was obtained in the same manner as in Example 1, except that the shielding members and conditions were adjusted so as to achieve the conditions shown in the table below.
In addition, for example, in Example 2, the second shielding member 12 and the third shielding member 13 are omitted.

<Results>
Table 1 shows the shielding members and conditions for each example, and the heat bias index for each example.
In Table 1, the aperture ratio refers to the aperture ratio of each shielding plate provided in each shielding member.
In Table 1, the maximum temperature difference is the value calculated by the method described above.
In Table 1, the values of D12/L1, D12/L2, D34/L3, D34/L4, X1H, and X4H are values determined by the method described above.

From the results in Table 1, and by comparing Examples 1 to 4 with Examples 5 to 6, it was confirmed that when the relationship of the above formula (x1) is satisfied (the value in the column of "(right side) - (left side) of formula (x1)" in Table 1 is positive), the heat bias in the reaction vessel 10 is suppressed.
Furthermore, from a comparison between Examples 1 and 3 and Examples 2 and 4, it was confirmed that when the first shielding member, the second shielding member, the third shielding member and the fourth shielding member are arranged in this order from the gas supply section side to the gas exhaust section side of the reaction vessel, the second shielding member and the third shielding member are arranged in an area of the reaction vessel that is covered by the heater, and the first shielding member and the fourth shielding member are arranged in an area of the reaction vessel that is not covered by the heater, the heat bias within the reaction vessel 10 is further suppressed.

<Graphene formation>
A rolled copper foil (manufactured by JX Metals Corporation) was used as the substrate S1, and graphene was formed on the substrate S1.
More specifically, under the conditions of Example 2, first, a mixed gas of argon gas and hydrogen gas (argon gas: 96.4 vol.%, hydrogen gas: 3.6 vol.%) was supplied from the gas supply unit 22 at 500 sccm, and the heater 26 was heated until the temperature measured by a thermocouple installed at the center position of the substrate S1 reached 1,050° C. After the temperature of the thermocouple reached 1,050° C., the temperature of the thermocouple was maintained at 1,050° C. for 40 minutes.

Next, the gas supply was switched to a feed gas containing a hydrocarbon. The feed gas contained 0.000658 vol% methane gas, 0.911392 vol% hydrogen gas, and 99.087950 vol% argon gas. After the gas supply was switched to the feed gas, the temperature of the thermocouple was held at 1,050° C. for 41 minutes.
Thereafter, the gas being supplied was switched to a gas containing only argon gas, the output of the heater 26 was set to 0 W, and the inside of the reaction vessel 10 was cooled.
After cooling, the substrate S1 was removed from the reaction vessel 10.

When the surface of the substrate S1 obtained by the above procedure was examined, it was confirmed that a film was attached to the surface. When the film was analyzed by Raman spectroscopy, a single-layer graphene sheet was confirmed. Furthermore, when examined with an optical microscope, 35.8% of the surface area of the substrate S1 was covered with graphene.

The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2023-220821, filed on December 27, 2023, are hereby incorporated by reference as the disclosure of the specification of the present invention.

REFERENCE SIGNS LIST 10 Reaction vessel 11 First shielding member 12 Second shielding member 13 Third shielding member 14 Fourth shielding member 22 Gas supply section 24 Gas exhaust section 26 Heater 100 Thermal CVD apparatus 110a, 110b, 110c Shielding plate

Claims (20)

A method for producing graphene using a thermal CVD apparatus, comprising:
The thermal CVD apparatus comprises:
A cylindrical reaction vessel in which a substrate for graphene production is housed;
a gas supply unit connected to the reaction vessel and configured to supply a raw material gas containing a hydrocarbon toward the base material contained inside the reaction vessel;
a gas exhaust part connected to the reaction vessel on the opposite side to the gas supply part side and configured to exhaust gas from inside the reaction vessel;
a heater that surrounds a region of the reaction vessel including a region in which the base material is accommodated and heats the inside of the reaction vessel;
a shielding member disposed inside the reaction vessel to block heat transfer inside the reaction vessel;
The shielding member is disposed at least between the gas supply unit and the substrate and between the substrate and the gas discharge unit,
wherein a flow rate of the raw material gas introduced from the gas supply unit is W, an internal cross-sectional area of the reaction vessel is S, and an inner diameter of the reaction vessel is x, the relationship of the following formula (x1) is satisfied.
Formula (x1) W/S ≦ 54.97×exp {-0.128×(x-4.0)}
In formula (x1), the unit of W is cm ³ /min, which represents the flow rate of gas per minute converted into a volume value at 1 atmospheric pressure and 0°C.
In formula (x1), the unit of S is ^cm2 .
In formula (x1), the unit of x is cm. a first shielding member, a second shielding member, a third shielding member and a fourth shielding member are disposed in this order in the reaction vessel from the gas supply part side to the gas discharge part side of the reaction vessel as the shielding members;
the second shielding member and the third shielding member are disposed in a region of the reaction vessel that is covered by the heater,
The graphene producing method according to claim 1 , wherein the first shielding member and the fourth shielding member are disposed in an area of the reaction vessel that is not covered by the heater. each of the first shielding member, the second shielding member, the third shielding member, and the fourth shielding member includes one or more shielding plates;
Each of the shielding plates has one or more holes;
3. The graphene production method according to claim 2, wherein an opening ratio of each of the shielding plates is 0.1 to 40% with respect to an internal cross-sectional area of the reaction vessel. each of the first shielding member, the second shielding member, the third shielding member, and the fourth shielding member is formed by arranging two or more of the shielding plates at a constant interval d1;
4. The graphene production method according to claim 3, wherein a ratio D12/d1 of a distance D12 between the first shielding member and the second shielding member to the interval d1, and a ratio D34/d1 of a distance D34 between the third shielding member and the fourth shielding member to the interval d1 are each 0.03 to 52.88. The length of the first shielding member is L1,
The length of the second shielding member is L2,
The length of the third shielding member is L3,
When the length of the fourth shielding member is L4,
a ratio D12/L1 of the distance D12 to the length L1 and a ratio D12/L2 of the distance D12 to the length L2 are each 0.01 to 23.27;
5. The graphene production method according to claim 4, wherein a ratio D34/L3 of the distance D34 to the length L3 and a ratio D34/L4 of the distance D34 to the length L4 are each 0.01 to 23.27. When the distance from the end of the area covered by the heater on the gas supply part side to the first shielding member is a distance D1H, a value X1H calculated by the following formula (1) using the distance D12 is 0.01 or more,
6. The graphene production method according to claim 4 or 5, wherein when a distance from an end of a region covered by the heater on the gas discharge part side to the fourth shielding member is a distance D4H, a value X4H calculated by the following formula (2) using the distance D34 is 0.01 or more.
Formula (1) X1H=(D12-D1H)/D12
Formula (2) X4H = (D34 - D4H) / D34 The method for producing graphene according to claim 6, wherein the value X1H and the value X4H are between 0.60 and 1.00. an aperture ratio of the shielding plate in the first shielding member is larger than an aperture ratio of the shielding plate in the second shielding member,
6. The method for producing graphene according to claim 3, wherein an aperture ratio of the shielding plate in the fourth shielding member is larger than an aperture ratio of the shielding plate in the third shielding member. The method for producing graphene according to any one of claims 3 to 5, wherein the product of the aperture ratios of the shielding plates constituting the first shielding member and the second shielding member and the product of the aperture ratios of the shielding plates constituting the third shielding member and the fourth shielding member are each 0.0009 to 0.0700%. the second shielding member includes two or more of the shielding plates, and the second shielding member includes the shielding plates having different aperture ratios;
6. The graphene production method according to claim 3, wherein the third shielding member includes two or more of the shielding plates, and the second shielding member includes the shielding plates having different aperture ratios. the second shielding member includes two or more of the shielding plates, and the aperture ratio of the shielding plate of the second shielding member arranged closest to the third shielding member is smaller than the aperture ratio of the shielding plate of the second shielding member arranged closest to the first shielding member,
6. The method for producing graphene according to any one of claims 3 to 5, wherein the third shielding member includes two or more of the shielding plates, and the aperture ratio of the shielding plate of the third shielding member arranged closest to the second shielding member is smaller than the aperture ratio of the shielding plate of the third shielding member arranged closest to the fourth shielding member. the first shielding member includes two or more of the shielding plates, and the aperture ratio of the shielding plate of the first shielding member arranged closest to the gas supply unit is smaller than the aperture ratio of the shielding plate of the first shielding member arranged closest to the second shielding member,
6. The method for producing graphene according to any one of claims 3 to 5, wherein the fourth shielding member includes two or more of the shielding plates, and the aperture ratio of the shielding plate of the fourth shielding member arranged closest to the gas discharge portion is smaller than the aperture ratio of the shielding plate of the fourth shielding member arranged closest to the third shielding member. The method for producing graphene according to any one of claims 3 to 5, wherein the shielding plate includes at least one selected from the group consisting of silicon oxide, silicon nitride, graphite, aluminum oxide, aluminum nitride, tantalum oxide, tantalum carbide, niobium oxide, niobium carbide, and molybdenum oxide. The method for producing graphene according to any one of claims 3 to 5, wherein the second shielding member and the third shielding member are made of metal. The method for producing graphene according to any one of claims 1 to 5, wherein a value obtained by dividing a temperature measured at the following first position by a temperature measured at the following second position is 0.62 or more.
First position: the axial position of the reaction vessel on the surface of the first shielding member facing the substrate. Second position: the axial position of the reaction vessel at the center of the substrate. Note that the units of the temperature measured at the first position and the temperature measured at the second position are °C. The method for producing graphene according to any one of claims 1 to 5, wherein the inner diameter of the reaction vessel is 12.7 to 38.1 cm. The method for producing graphene according to any one of claims 1 to 5, wherein the inner diameter of the reaction vessel is 15.24 to 35.56 cm. The method for producing graphene according to any one of claims 1 to 5, wherein the inner diameter of the reaction vessel is 20.32 to 30.48 cm. The method for producing graphene according to any one of claims 1 to 5, wherein the reaction vessel contains silicon dioxide. The method for producing graphene according to any one of claims 1 to 5, comprising: placing the substrate including a metal film including at least one selected from the group consisting of copper, nickel, and iron in the reaction vessel; supplying a raw material gas including a hydrocarbon from the gas supply unit; and heating the inside of the reaction vessel to 900 to 1,100°C with the heater to form a graphene layer on the metal film.

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