Graphene Device

Abstract

To provide a graphene element that can suppress variation in properties affected by solvent and resist residues used during graphene transfer.SOLUTION: A graphene element 100 has a substrate 110, a boron nitride layer 120, a graphene layer 130, an insulating layer 140, a source electrode 151, a drain electrode 152, and a gate electrode 153. The boron nitride layer 120 has a plurality of boron nitride, a layered material, stacked on top of each other. The graphene layer 130 contacts the top 121 and side 122 of the boron nitride layer 120. The graphene layer 130 has one or more graphene, a layered substance, stacked on top of each other.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to graphene devices. [Background technology]

[0002] A graphene element has been proposed in which hexagonal boron nitride is transferred onto a silicon substrate having a silicon oxide film formed on the upper surface thereof, and graphene is then provided on the boron nitride by transfer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2019-522348 [Patent Document 2] JP 2016-58631 A [Non-patent literature]

[0004] [Non-Patent Document 1] Boron nitride substrates for high-quality graphene electronics, NATURE NANOTECHNOLOGY, VOL 5, OCTOBER 2010 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional graphene devices are not suitable for commercial use because it is difficult to control the transfer position. Although it is easy to fabricate devices using large-area graphene produced by synthesis, the characteristics tend to vary due to the effects of the solvent used during transfer and the residue of the resist.

[0006] An object of the present disclosure is to provide a graphene element capable of suppressing the variation in characteristics caused by the influence of solvents and resist residues used during graphene transfer. [Means for solving the problem]

[0007] According to one embodiment of the present disclosure, there is provided a method for fabricating a semiconductor device comprising the steps of: forming a layer of boron nitride having a turbostratic structure; and forming a graphene layer in contact with the layer of boron nitride; A substrate; Have The boron nitride layer is located between the substrate and the graphene layer. A graphene device is provided. Effect of the Invention

[0008] According to the present disclosure, it is possible to suppress variations in characteristics that are influenced by solvents and resist residues used during graphene transfer. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view (part 1) showing a graphene element according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view (part 2) showing the graphene element according to the first embodiment. [Diagram 3] 1A to 1C are cross-sectional views (part 1) illustrating a method for manufacturing a graphene element according to a first embodiment. [Figure 4] 5A to 5C are cross-sectional views (part 2) illustrating the method for manufacturing the graphene element according to the first embodiment. [Diagram 5] 5A to 5C are cross-sectional views (part 3) illustrating the method for manufacturing the graphene element according to the first embodiment. [Figure 6] 4 is a cross-sectional view (part 4) illustrating the method for manufacturing the graphene element according to the first embodiment. FIG. [Figure 7] 5 is a cross-sectional view (part 5) illustrating the method for manufacturing the graphene element according to the first embodiment. FIG. [Figure 8] 6 is a cross-sectional view (part 6) illustrating the method for manufacturing the graphene element according to the first embodiment. FIG. [Figure 9] FIG. 7 is a cross-sectional view showing the method for manufacturing the graphene element according to the first embodiment. [Figure 10] FIG. 2 is a plan view (part 1) illustrating the method for manufacturing the graphene element according to the first embodiment. [Figure 11] FIG. 2 is a plan view (part 2) illustrating the method for manufacturing the graphene element according to the first embodiment. [Figure 12] FIG. 1 is a cross-sectional view (part 1) showing a graphene element according to a second embodiment. [Figure 13] FIG. 2 is a cross-sectional view (part 2) showing the graphene element according to the second embodiment. [Figure 14] 1A to 1C are cross-sectional views (part 1) illustrating a method for manufacturing a graphene element according to a second embodiment. [Figure 15] 11A to 11C are cross-sectional views (part 2) illustrating the method for manufacturing the graphene element according to the second embodiment. [Figure 16] 11A to 11C are cross-sectional views (part 3) illustrating the method for manufacturing the graphene element according to the second embodiment. [Figure 17] 11A to 11C are cross-sectional views (part 4) illustrating the method for manufacturing the graphene element according to the second embodiment. [Figure 18] 5 is a cross-sectional view (part 5) illustrating the method for manufacturing the graphene element according to the second embodiment. FIG. [Figure 19] FIG. 1 is a cross-sectional view (part 1) showing a graphene element according to a third embodiment. [Figure 20] FIG. 11 is a cross-sectional view (part 2) showing the graphene element according to the third embodiment. [Figure 21] 11A to 11C are cross-sectional views (part 1) illustrating a method for manufacturing a graphene element according to a fourth embodiment. [Figure 22] 13A to 13C are cross-sectional views (part 2) illustrating the method for manufacturing the graphene element according to the fourth embodiment. [Figure 23] 13A to 13C are cross-sectional views (part 3) illustrating the method for manufacturing the graphene element according to the fourth embodiment. [Figure 24] 13A to 13C are cross-sectional views (part 4) illustrating the method for manufacturing the graphene element according to the fourth embodiment. [Diagram 25] 13 is a cross-sectional view (part 5) illustrating the method for manufacturing the graphene element according to the fourth embodiment. [Figure 26] FIG. 13 is a cross-sectional view (part 6) illustrating the method for manufacturing the graphene element according to the fourth embodiment. [Figure 27]FIG. 13 is a cross-sectional view (part 7) illustrating the method for manufacturing the graphene element according to the fourth embodiment. [Figure 28] FIG. 8 is a cross-sectional view showing the method for manufacturing the graphene element according to the fourth embodiment. [Figure 29] FIG. 11 is a cross-sectional view showing a graphene device according to a fifth embodiment. [Diagram 30] 13A to 13C are cross-sectional views (part 1) illustrating a method for manufacturing a graphene element according to a fifth embodiment. [Diagram 31] 13A to 13C are cross-sectional views (part 2) illustrating the method for manufacturing the graphene element according to the fifth embodiment. [Diagram 32] 13A to 13C are cross-sectional views (part 3) illustrating the method for manufacturing the graphene element according to the fifth embodiment. [Diagram 33] 13A to 13C are cross-sectional views (part 4) illustrating the method for manufacturing the graphene element according to the fifth embodiment. [Diagram 34] 13 is a cross-sectional view (part 5) illustrating the method for manufacturing the graphene element according to the fifth embodiment. [Diagram 35] 13 is a cross-sectional view (part 6) illustrating the method for manufacturing the graphene element according to the fifth embodiment. FIG. [Diagram 36] FIG. 13 is a cross-sectional view showing a graphene device according to a sixth embodiment. [Figure 37] FIG. 1 shows the results of Raman analysis. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are denoted by the same reference numerals, and redundant description may be omitted.

[0011] (First embodiment) First, a first embodiment will be described. Figures 1 and 2 are cross-sectional views showing a graphene element according to the first embodiment. Figure 1 corresponds to a cross-sectional view taken along line II in Figure 2, and Figure 2 corresponds to a cross-sectional view taken along line II-II in Figure 1.

[0012] As shown in Figures 1 and 2, the graphene device 100 according to the first embodiment has a substrate 110, a boron nitride layer 120, a graphene layer 130, an insulating layer 140, a source electrode 151, a drain electrode 152, and a gate electrode 153.

[0013] The substrate 110 includes a silicon substrate 111 and a silicon oxide film 112 formed on the upper surface of the silicon substrate 111. The substrate 110 is, for example, a silicon substrate with a thermal oxide film. The substrate 110 may be an insulating substrate such as a sapphire substrate.

[0014] The boron nitride layer 120 is provided on a portion of the upper surface of the substrate 110. The boron nitride layer 120 has a turbostratic structure. The boron nitride layer 120 has a plurality of boron nitrides, which are layered substances, stacked on top of each other. Each boron nitride may have, for example, a hexagonal crystal structure. The thickness of the boron nitride layer 120 is, for example, 20 nm to 200 nm.

[0015] The graphene layer 130 covers the boron nitride layer 120. The graphene layer 130 contacts the top surface 121 and the side surface 122 of the boron nitride layer 120. The graphene layer 130 includes one or more pieces of graphene, which is a layered material, stacked on top of each other.

[0016] The source electrode 151 contacts a part of the graphene layer 130, and the drain electrode 152 contacts another part of the graphene layer 130. The source electrode 151 and the drain electrode 152 have, for example, a titanium film and a gold film on the titanium film. The titanium film contacts the graphene layer 130. For example, the thickness of the titanium film is 1 nm to 10 nm, and the thickness of the gold film is 20 nm to 100 nm. The source electrode 151 and the drain electrode 152 are an example of a first electrode and a second electrode.

[0017] Between the source electrode 151 and the drain electrode 152, the graphene layer 130 is covered with the insulating layer 140. The insulating layer 140 is, for example, an aluminum oxide film having a thickness of 5 nm to 20 nm. The insulating layer 140 may be a boron nitride layer having a turbostratic structure.

[0018] The gate electrode 153 covers the insulating layer 140 between the source electrode 151 and the drain electrode 152. The gate electrode 153 is separated from the source electrode 151 and the drain electrode 152. The gate electrode 153 has, for example, a titanium film and a gold film on the titanium film. The titanium film is in contact with the insulating layer 140. For example, the titanium film has a thickness of 1 nm to 10 nm, and the gold film has a thickness of 20 nm to 100 nm. The gate electrode 153 is an example of a control electrode and a third electrode.

[0019] In the first embodiment, the insulating layer 140 functions as a gate insulating film. Therefore, the graphene device 100 can be used as a field effect transistor having a top gate structure.

[0020] Next, a method for manufacturing the graphene device 100 according to the first embodiment will be described. Fig. 3 to Fig. 9 are cross-sectional views showing the method for manufacturing the graphene device 100 according to the first embodiment. Fig. 10 and Fig. 11 are plan views showing the method for manufacturing the graphene device 100 according to the first embodiment. Fig. 5 corresponds to a cross-sectional view taken along line VV in Fig. 10, and Fig. 6 corresponds to a cross-sectional view taken along line VI-VI in Fig. 11.

[0021] 3, a substrate 110 having a silicon substrate 111 and a silicon oxide film 112 is prepared. The substrate 110 can be formed, for example, by thermally oxidizing one surface of a silicon substrate. A silicon substrate with a thermal oxide film can be used as the substrate 110.

[0022] 4, a boron nitride layer 120 having a turbostratic structure is formed on the silicon oxide film 112. The boron nitride layer 120 having a turbostratic structure can be formed by, for example, a sputtering method using a boron nitride target having a hexagonal crystal structure. When using the sputtering method, argon, nitrogen, or a mixture of these gases may be used as the gas used. The boron nitride layer 120 may also be formed by an electron beam method. The temperature of the substrate 110 when forming the boron nitride layer 120 is, for example, 20°C to 1000°C.

[0023] 5 and 10, the boron nitride layer 120 is processed into a predetermined shape. The boron nitride layer 120 can be processed by reactive ion etching (RIE) using oxygen plasma or the like.

[0024] 6 and 11, the graphene layer 130 is formed so as to cover the boron nitride layer 120. The graphene layer 130 can be synthesized by, for example, a thermal chemical vapor deposition (CVD) method. The graphene layer 130 grows from the upper surface 121 and the side surface 122 of the boron nitride layer 120. For example, the temperature of the substrate 110 when forming the graphene layer 130 is set to 600°C to 800°C, and the pressure in the chamber is set to 0.8 kPa to 1.2 kPa. For example, acetylene gas can be used as a raw material for the graphene layer 130. The acetylene gas is supplied into the chamber as a mixed gas with a dilution gas such as argon gas. The ratio of the argon gas in the mixed gas is, for example, 5% by volume to 15% by volume. Instead of the acetylene gas, a hydrocarbon gas such as methane gas and ethylene gas may be used as the raw material gas, or an alcohol gas such as ethanol and methanol may be used. As the diluent gas, helium gas or hydrogen gas may be used instead of argon gas. Also, a mixture of diluent gases may be used.

[0025] 7, the source electrode 151 and the drain electrode 152 are formed. The source electrode 151 and the drain electrode 152 can be formed by, for example, deposition and lift-off. That is, the region where the source electrode 151 and the drain electrode 152 are to be formed are exposed, and a photoresist pattern is formed to cover the other regions, and a metal film is deposited by a deposition method or the like using this pattern as a growth mask, and this pattern is removed together with the metal film thereon. In forming the metal film, for example, a titanium film is formed, and a gold film is formed thereon.

[0026] Thereafter, an insulating layer covering the graphene layer 130, the source electrode 151, and the drain electrode 152 is formed on the substrate 110. Next, as shown in FIG. 8, the insulating layer is removed between the source electrode 151 and the drain electrode 152 except for the portion covering the graphene layer 130. As a result, an insulating layer 140 is obtained as shown in FIG. 8. When the insulating layer 140 is an aluminum oxide layer, the insulating layer can be formed by, for example, a thermal atomic layer deposition (ALD) method. When the insulating layer 140 is a boron nitride layer having a turbostratic structure, the insulating layer can be formed by, for example, a sputtering method.

[0027] 9, the gate electrode 153 is formed. The gate electrode 153 can be formed by, for example, deposition and lift-off. That is, the region where the gate electrode 153 is to be formed is exposed, and a photoresist pattern is formed to cover the other regions, and a metal film is deposited by a deposition method or the like using this pattern as a growth mask, and this pattern is removed together with the metal film thereon. In forming the metal film, for example, a titanium film is formed, and a gold film is formed thereon.

[0028] In this manner, the graphene device 100 according to the first embodiment can be manufactured.

[0029] In the first embodiment, the graphene layer 130 is in contact with the boron nitride layer 120 having a turbostratic structure. Therefore, the graphene layer 130 can be directly synthesized on the boron nitride layer 120. Therefore, there is no need to transfer the graphene layer 130 onto the boron nitride layer 120.

[0030] When the graphene layer 130 is transferred onto the boron nitride layer 120, residues are generated due to the solvent or resist used when removing the substrate used for the transfer, and the characteristics tend to vary due to the residues. According to the present embodiment, since it is not necessary to transfer the graphene layer 130 onto the boron nitride layer 120, the generation of residues due to the transfer can be prevented. Therefore, the variation in the characteristics of the graphene device 100 can be suppressed.

[0031] Furthermore, in this embodiment, the graphene layer 130 can be grown from the upper surface 121 and the side surface 122 of the boron nitride layer 120 having a turbostratic structure. This ensures a large contact area between the graphene layer 130 and the source electrode 151 and the drain electrode 152, thereby reducing contact resistance. Furthermore, various structures can be constructed using the graphene layer 130 grown from the upper surface 121 and the side surface 122 of the boron nitride layer 120.

[0032] Note that between the source electrode 151 and the drain electrode 152, the insulating layer 140 does not need to cover both the top surface and the side surface of the graphene layer 130; for example, the insulating layer 140 may cover only the top surface of the graphene layer 130. In addition, the gate electrode 153 does not need to cover both the top surface and the side surface of the insulating layer 140; for example, the gate electrode 153 may cover only the top surface of the insulating layer 140.

[0033] Second embodiment Next, a second embodiment will be described. The second embodiment differs from the first embodiment mainly in the structure of the gate electrode. Fig. 12 and Fig. 13 are cross-sectional views showing a graphene element according to the second embodiment. Fig. 12 corresponds to a cross-sectional view taken along line XII-XII in Fig. 13, and Fig. 13 corresponds to a cross-sectional view taken along line XIII-XIII in Fig. 12.

[0034] As shown in FIGS. 12 and 13, the graphene device 200 according to the second embodiment has a gate electrode 253 instead of the gate electrode 153 in the first embodiment.

[0035] The gate electrode 253 is provided on the substrate 110 under the boron nitride layer 120 between the source electrode 151 and the drain electrode 152. The gate electrode 253 is covered by the boron nitride layer 120. The gate electrode 253 has, for example, a titanium film and a gold film on the titanium film. The gate electrode 253 is an example of a control electrode and a fourth electrode.

[0036] The other configuration is similar to that of the first embodiment.

[0037] In the second embodiment, the boron nitride layer 120 functions as a gate insulating film. Therefore, the graphene device 200 can be used as a field effect transistor having a buried gate structure. In addition, the insulating layer 140 functions as a protective layer for the graphene layer 130. The insulating layer 140 does not necessarily have to be provided.

[0038] Next, a method for manufacturing the graphene device 200 according to the second embodiment will be described. Figures 14 to 18 are cross-sectional views showing the method for manufacturing the graphene device 200 according to the second embodiment.

[0039] First, as shown in Fig. 14, the substrate 110 is prepared in the same manner as in the first embodiment. Next, the gate electrode 253 is formed on the silicon oxide film 112. The gate electrode 253 can be formed by, for example, deposition and lift-off. That is, the region where the gate electrode 253 is to be formed is exposed, and a photoresist pattern is formed to cover the other regions, and a metal film is deposited by a deposition method or the like using this pattern as a growth mask, and this pattern is removed together with the metal film thereon. In forming the metal film, for example, a titanium film is formed, and a gold film is formed thereon.

[0040] 15, a boron nitride layer 120 having a turbostratic structure is formed on the silicon oxide film 112 so as to cover the gate electrode 253. The boron nitride layer 120 having a turbostratic structure can be formed by a sputtering method using a boron nitride target having a hexagonal crystal structure, for example, as in the first embodiment.

[0041] 16, the boron nitride layer 120 is processed into a predetermined shape. The boron nitride layer 120 can be processed by RIE using oxygen plasma or the like, as in the first embodiment.

[0042] 17, the graphene layer 130 is formed so as to cover the boron nitride layer 120. The graphene layer 130 can be synthesized by, for example, a thermal CVD method, similarly to the first embodiment.

[0043] Thereafter, as shown in FIG. 18, a source electrode 151, a drain electrode 152, and an insulating layer 140 are formed in the same manner as in the first embodiment.

[0044] In this manner, the graphene device 200 according to the second embodiment can be manufactured.

[0045] In the second embodiment, the graphene layer 130 is in contact with the boron nitride layer 120 having a turbostratic structure. Therefore, similar to the first embodiment, the variation in characteristics of the graphene device 200 can be suppressed.

[0046] Third embodiment Next, a third embodiment will be described. The third embodiment differs from the first embodiment and the like mainly in the structure of the gate electrode. Fig. 19 and Fig. 20 are cross-sectional views showing a graphene element according to the third embodiment. Fig. 19 corresponds to a cross-sectional view taken along line XIX-XIX in Fig. 20, and Fig. 20 corresponds to a cross-sectional view taken along line XX-XX in Fig. 19.

[0047] As shown in FIGS. 19 and 20, the graphene device 300 according to the third embodiment has the gate electrode 253 according to the second embodiment in addition to the gate electrode 153 according to the first embodiment.

[0048] The other configuration is similar to that of the first embodiment.

[0049] In the third embodiment, the boron nitride layer 120 and the insulating layer 140 function as a gate insulating film. Therefore, the graphene element 300 can be used as a field effect transistor having a double gate structure. It can also be said that the graphene element 300 has a partial surround gate structure.

[0050] When manufacturing the graphene device 300 according to the third embodiment, for example, the gate electrode 253 is formed in the same manner as in the second embodiment, and then the boron nitride layer 120 and the graphene layer 130 are formed, and the gate electrode 153 is formed in the same manner as in the first embodiment.

[0051] (Fourth embodiment) Next, a fourth embodiment will be described. The fourth embodiment differs from the first embodiment in terms of the manufacturing method. Figures 21 to 28 are cross-sectional views showing a manufacturing method of the graphene element according to the fourth embodiment.

[0052] First, as shown in Fig. 21, a substrate 460 for growth is prepared. The substrate 460 has, for example, a silicon substrate 461 and a silicon oxide film 462. The substrate 460 can be formed, for example, by thermally oxidizing one surface of a silicon substrate. As the substrate 460, a silicon substrate with a thermal oxide film can be used.

[0053] 22, a catalytic metal layer 470 is formed on the silicon oxide film 462. The catalytic metal layer 470 contains, for example, iron, nickel, or cobalt. The catalytic metal layer 470 has a thickness of, for example, 20 nm to 500 nm. The catalytic metal layer 470 can be formed by, for example, a sputtering method or an electron beam method.

[0054] 23, a boron nitride layer 420 having a turbostratic structure is formed on the catalytic metal layer 470. The boron nitride layer 420 having a turbostratic structure can be formed by, for example, a sputtering method using a boron nitride target having a hexagonal crystal structure. The boron nitride layer 420 may be formed by a metal organic chemical vapor deposition (MOCVD) method, an electron beam (EB) method, or a molecular beam epitaxy (MBE) method. The temperature of the substrate 460 when the boron nitride layer 420 is formed is, for example, 20°C to 1000°C.

[0055] 24, a graphene layer 430 is formed on the boron nitride layer 420. The graphene layer 430 can be synthesized by, for example, a thermal CVD method. The graphene layer 430 grows from an upper surface 421 and a side surface 422 of the boron nitride layer 420. The graphene layer 430 can be formed in a similar manner to the graphene layer 130.

[0056] 25, a support member 480 for transfer is formed on the upper surface of the graphene layer 430. The material of the support member 480 may be, for example, a resin such as polymethylmethacrylate resin (PMMA).

[0057] 26, the catalytic metal layer 470 is removed to separate the stack of the boron nitride layer 420, the graphene layer 430, and the support member 480 from the substrate 460. The catalytic metal layer 470 can be removed using, for example, hydrochloric acid.

[0058] 27, the boron nitride layer 420 and the graphene layer 430 are transferred to a substrate 410. The substrate 410 has, for example, a silicon substrate 411 and a silicon oxide film 412. The substrate 410 can be formed, for example, by thermally oxidizing one surface of a silicon substrate. A silicon substrate with a thermal oxide film can be used as the substrate 410. The boron nitride layer 420 and the graphene layer 430 are transferred so that the boron nitride layer 420 is in contact with the silicon oxide film 412. A silicon substrate or the like can be used as the substrate 410. When transferring the boron nitride layer 420 and the graphene layer 430, the support member 480 can be removed using an organic solvent or the like.

[0059] Next, as shown in FIG. 28, similarly to the first embodiment, processes from the formation of the source electrode 151 and the drain electrode 152 to the formation of the gate electrode 153 are performed.

[0060] In this manner, the graphene device 400 according to the fourth embodiment can be manufactured.

[0061] In the fourth embodiment, the graphene layer 430 is in contact with the boron nitride layer 420 having a turbostratic structure. Therefore, similarly to the first embodiment, it is possible to suppress the variation in the characteristics of the graphene element 400. In addition, since the boron nitride layer 420 is formed using the catalytic metal layer 470, it is easy to obtain the boron nitride layer 420 and the graphene layer 430 of particularly good quality.

[0062] Fifth embodiment Next, a fifth embodiment will be described. The fifth embodiment differs from the first embodiment etc. mainly in the configurations of the boron nitride layer and the graphene layer. Fig. 29 is a cross-sectional view showing the graphene device according to the fifth embodiment.

[0063] As shown in FIG. 29, the graphene device 500 according to the fifth embodiment has a substrate 410, a boron nitride layer 520 and a graphene layer 530 instead of the substrate 110, the boron nitride layer 120 and the graphene layer 130 in the first embodiment.

[0064] The graphene layer 530 is provided on a portion of the top surface of the substrate 410. The graphene layer 530 includes one or more graphenes, which are layered materials, stacked on top of each other.

[0065] The boron nitride layer 520 is provided on the graphene layer 530. The boron nitride layer 520 has a turbostratic structure. The boron nitride layer 520 has a plurality of boron nitrides, which are layered substances, stacked on each other. Each boron nitride may have, for example, a hexagonal crystal structure. The boron nitride layer 520 has a thickness of, for example, 20 nm to 200 nm. The graphene layer 530 contacts the lower surface 523 of the boron nitride layer 520.

[0066] The other configuration is similar to that of the first embodiment.

[0067] In the fifth embodiment, the insulating layer 140 and the boron nitride layer 520 function as a gate insulating film. Therefore, the graphene device 500 can be used as a field effect transistor having a top gate structure.

[0068] Next, a method for manufacturing the graphene device 500 according to the fifth embodiment will be described. Fig. 30 to Fig. 35 are cross-sectional views showing the method for manufacturing the graphene device 500 according to the fifth embodiment.

[0069] 30, a growth substrate 460 is prepared in the same manner as in the fourth embodiment, a catalytic metal layer 470 is formed on a silicon oxide film 462, and a boron nitride layer 520 having a turbostratic structure is formed on the catalytic metal layer 470. Instead of the silicon oxide film 462, another insulating film such as an aluminum oxide film may be used.

[0070] 31, a graphene layer 530 is formed between the catalytic metal layer 470 and the boron nitride layer 520. The graphene layer 530 can be synthesized by, for example, a thermal CVD method. The graphene layer 530 grows from the upper surface of the catalytic metal layer 470 and contacts the lower surface 523 of the boron nitride layer 520.

[0071] 32, a support member 580 for transfer is formed on the upper surface of the boron nitride layer 520. The material of the support member 580 may be, for example, a resin such as PMMA.

[0072] 33, the catalytic metal layer 470 is removed to separate the stack of the boron nitride layer 520, the graphene layer 530, and the support member 580 from the substrate 460. The catalytic metal layer 470 can be removed using, for example, hydrochloric acid.

[0073] 34, the boron nitride layer 520 and the graphene layer 530 are transferred to the substrate 410. The boron nitride layer 520 and the graphene layer 530 are transferred such that the graphene layer 530 is in contact with the silicon oxide film 412. When transferring the boron nitride layer 520 and the graphene layer 530, the support member 580 can be removed using an organic solvent or the like.

[0074] Next, as shown in FIG. 35, similarly to the first embodiment, processes from the formation of the source electrode 151 and the drain electrode 152 to the formation of the gate electrode 153 are performed.

[0075] In this manner, the graphene device 500 according to the fifth embodiment can be manufactured.

[0076] In the fifth embodiment, the graphene layer 530 is in contact with the boron nitride layer 520 having a turbostratic structure. Therefore, similar to the first embodiment, it is possible to suppress the variation in the characteristics of the graphene element 500. In addition, since the boron nitride layer 520 and the graphene layer 530 are formed using the catalyst metal layer 470, it is easy to obtain the boron nitride layer 520 and the graphene layer 530 of particularly good quality. Furthermore, since the support member 580 is in contact with the boron nitride layer 520 rather than the graphene layer 530, it is possible to suppress the variation in characteristics due to the residue of the support member 580.

[0077] Sixth embodiment Next, a sixth embodiment will be described. The sixth embodiment differs from the fifth embodiment etc. mainly in the configuration of the substrate. Fig. 36 is a cross-sectional view showing the graphene device according to the sixth embodiment.

[0078] 36, the graphene device 600 according to the sixth embodiment has a substrate 610 instead of the substrate 410 in the fifth embodiment. The substrate 610 has a silicon substrate 611 and a boron nitride layer 612 provided on the upper surface of the silicon substrate 611. The boron nitride layer 612 has a hexagonal crystal structure. The boron nitride layer 612 is provided on the silicon substrate 611 by, for example, transfer.

[0079] The other configuration is similar to that of the fifth embodiment.

[0080] In the present disclosure, the shape of the electrodes and wiring connected to the graphene layer is not limited. For example, the graphene element may have a three-dimensional structure using a graphene layer grown from the side surface of a boron nitride layer having a turbostratic structure.

[0081] Here, the results of Raman analysis of a sample prepared by forming a boron nitride layer having a turbostratic structure on a substrate and growing a graphene layer from the back surface of the boron nitride layer according to the fifth embodiment will be described. Fig. 37 shows the results of Raman analysis. Fig. 37 shows a Raman spectrum S1 measured before growing the graphene layer and a Raman spectrum S2 measured after growing the graphene layer.

[0082] In the Raman spectrum S1, 1300 cm -1 The D band peak P11 originating from the boron nitride layer appears nearby. In the Raman spectrum S2, the peak at 1300 cm -1 Nearby, a peak P21 appears, which is a superposition of the D band peak derived from the boron nitride layer and the D band peak derived from the graphene layer. In addition, in the Raman spectrum S2, a peak at 1580 cm -1 Nearby, the G band peak P22 originating from the graphene layer appears at 2700 cm -1 The graphene layer-derived 2D band peak P23 appears nearby. The analysis results shown in Figure 37 indicate that a graphene layer of good quality has been formed.

[0083] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

[0084] Various aspects of the present disclosure are summarized below as appendices.

[0085] (Appendix 1) a boron nitride layer having a turbostratic structure; a graphene layer in contact with the boron nitride layer; A graphene element comprising: (Appendix 2) A substrate is provided. 2. The graphene device according to claim 1, wherein the boron nitride layer is located between the substrate and the graphene layer. (Appendix 3) A substrate is provided. 2. The graphene device of claim 1, wherein the graphene layer is located between the substrate and the boron nitride layer. (Appendix 4) a first electrode in contact with the graphene layer; a second electrode in contact with the graphene layer; 4. The graphene device according to claim 1, further comprising: (Appendix 5) The graphene element described in appendix 4, further comprising a control electrode for controlling a potential of a portion of the graphene layer between the first electrode and the second electrode. (Appendix 6) an insulating layer covering at least a portion of the graphene layer; The graphene element described in Appendix 5, wherein the control electrode has a third electrode covering at least a portion of the insulating layer. (Appendix 7) The graphene element described in Appendix 5 or 6, characterized in that the control electrode has a fourth electrode provided under the boron nitride layer. (Appendix 8) forming a layer of boron nitride having a turbostratic structure on a substrate; growing a graphene layer from a surface of the boron nitride layer; A method for producing a graphene element, comprising: [Explanation of symbols]

[0086] 100, 200, 300, 400, 500, 600: Graphene elements 110, 410, 610: Substrate 120, 420, 520: Boron nitride layer 130, 430, 530: Graphene layers 151: Source electrode 152: Drain electrode 153, 253: gate electrode

Claims

1. A boron nitride layer having a turbostratic structure, a graphene layer in contact with the boron nitride layer; A substrate; having A graphene device, characterized in that the boron nitride layer is located between the substrate and the graphene layer.

2. A boron nitride layer having a turbostratic structure, a graphene layer in contact with the boron nitride layer; A substrate; A graphene device, characterized in that the graphene layer is located between the substrate and the boron nitride layer.

3. a first electrode in contact with the graphene layer; a second electrode in contact with the graphene layer; The graphene element according to claim 1 or 2, characterized in that

4. The graphene device according to claim 3 , further comprising a control electrode for controlling a potential of a portion of the graphene layer between the first electrode and the second electrode.

5. an insulating layer covering at least a portion of the graphene layer; The graphene device according to claim 4 , wherein the control electrode includes a third electrode covering at least a portion of the insulating layer.

6. A boron nitride layer having a turbostratic structure, a graphene layer in contact with the boron nitride layer; a first electrode in contact with the graphene layer; a second electrode in contact with the graphene layer; a control electrode for controlling a potential of a portion of the graphene layer between the first electrode and the second electrode; an insulating layer covering at least a portion of the graphene layer; having The graphene element, wherein the control electrode has a third electrode covering at least a portion of the insulating layer. A graphene element comprising:

7. The graphene device according to any one of claims 4 to 6, wherein the control electrode has a fourth electrode provided under the boron nitride layer.

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