JP5303957B2 - Graphene substrate and manufacturing method thereof - Google Patents

Description

  The present invention relates to a graphene substrate having graphene which is a hexagonal arrangement of carbon atoms forming a two-dimensional sheet, and a method for manufacturing the same.

  In recent years, graphene, which is a single-layer hexagonal carbon atom forming a two-dimensional sheet, has attracted attention as a new electronic device material.

This graphene can be formed on the surface of a silicon carbide substrate by, for example, heat-treating the silicon carbide substrate in a vacuum to sublimate silicon atoms (Patent Document 1).
JP 2007-335532 A

  As shown in Patent Document 1, by using a silicon carbide substrate, it is possible to easily form wafer-sized graphene on the surface of the silicon carbide substrate. That is, a graphene substrate having wafer-size graphene can be formed over a support substrate including a silicon carbide substrate.

  However, silicon carbide substrates are expensive. Further, since the silicon carbide substrate is hard, there is a possibility that it becomes an obstacle to subsequent processes. Therefore, a graphene substrate having wafer-size graphene on a support substrate other than a silicon carbide substrate is required as a support substrate.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a graphene substrate having wafer-size graphene without using a silicon carbide substrate as a support substrate, and to provide a method for manufacturing the same.

In order to achieve the above object, a graphene substrate according to claim 1 includes graphene, a support substrate that supports graphene, and an adhesive layer that bonds the graphene and the support substrate, and the adhesive layer is amorphous silicon or amorphous. and I am characterized in carbon Tona Rukoto.

In this manner, by bonding the graphene and the supporting substrate with the adhesive layer, a graphene substrate having wafer-sized graphene can be obtained without using a silicon carbide substrate as the supporting substrate. As the adhesive layer, as shown in claim 1, amorphous silicon or amorphous carbon can be used.

In order to achieve the above object, a method for producing a graphene substrate according to claim 2 includes a graphene forming step of forming graphene on a surface of the single crystal silicon carbide substrate by heat-treating the single crystal silicon carbide substrate, Adhesive layer forming step of forming an adhesive layer on graphene, a bonding step of bonding a support substrate to the single crystal silicon carbide substrate via the adhesive layer, and a single crystal silicon carbide substrate bonded to the single crystal silicon carbide substrate and the support And a peeling step of peeling the single crystal silicon carbide substrate from the substrate.

  In this way, after the graphene-formed single crystal silicon carbide substrate and the support substrate are bonded to each other through the adhesive layer, the single crystal silicon carbide substrate is peeled off, whereby the graphene is formed on the support substrate through the adhesive layer. Can be formed. That is, when an adhesive layer is used, graphene formed on the surface of the single crystal silicon carbide substrate can be transferred to the supporting substrate.

  Wafer-sized graphene can be formed on the surface of the single crystal silicon carbide substrate. Therefore, wafer-sized graphene can be formed over the supporting substrate through the adhesive layer. That is, a graphene substrate having wafer-size graphene can be formed over a supporting substrate other than a silicon carbide substrate.

In the graphene formation step, as shown in claim 3 , graphene may be formed on the entire main surface of the single crystal silicon carbide substrate, or as shown in claim 4 , the single crystal silicon carbide substrate. Graphene may be partially formed on the surface of the film.

  When graphene is formed over the entire main surface, a graphene substrate having a relatively large area of graphene can be obtained, which is preferable. On the other hand, when graphene is partially formed, distortion due to a difference in thermal expansion coefficient between the support substrate and graphene can be reduced, which is preferable.

In addition, when graphene is partially formed, as shown in claim 5 , it can be formed by patterning graphene by photolithography.

Moreover, as shown in claim 6 , an adhesive layer patterning step of patterning an adhesive layer formed on graphene before the bonding step may be provided. By patterning the adhesive layer in this way, the graphene formed on the surface of the single crystal silicon carbide substrate has a portion where the adhesive layer is not removed by patterning (that is, a portion where the adhesive layer remains on the graphene) ) Only on the support substrate. Therefore, the graphene can also be partially formed on the support substrate by the ninth aspect.

Moreover, as shown in claim 7 , a defect introduction step of introducing defects into at least a part of the graphene may be provided.

  By doing so, the bond between the graphene and the adhesive layer can be strengthened, so that the graphene can be easily formed on the supporting substrate.

As the adhesive layer, as shown in claim 8 , at least one of amorphous silicon, silicon dioxide, and amorphous carbon can be used.

Further, as shown in claim 9 , in the bonding step, after bonding by hydrogen bonding, heat treatment may be performed and converted to covalent bonding by dehydrogenation reaction.

  By doing so, since the bond between the adhesive layer and the support substrate can be strengthened, graphene can be easily formed on the support substrate.

As the support substrate, as shown in claim 1 0, it is possible to use at least one of a silicon substrate and a quartz substrate.

Further, as shown in Claim 1 1, when the supporting substrate is a silicon substrate, the inside of the silicon substrate, prior to the bonding step, as element components for constituting the silicon semiconductor element is formed It is preferable. That is, it is preferable to use a silicon substrate on which element components are formed as the support substrate. This is because it is difficult to form element components after graphene is formed on the support substrate.

Further, the peeling process, according to claim 1 to a single crystal silicon carbide substrate from the support substrate as shown in 2 may be mechanically peeled, graphene and a single crystal silicon carbide substrate as shown in claim 1 3 It is also possible to introduce a vaporizing substance between the two and peel off by expansion of the vaporizing substance. Note that, as shown in claims 1 to 3, by peeling off by the expansion of the vaporized material can be easily peeled off.

Specific examples of the vaporization material, sulfuric acid group was introduced at the acid treatment after the graphene forming step as shown in claim 1 4, or, using hydrogen ion implantation after the graphene forming step as shown in claim 1 5 be able to.

Furthermore, as shown in claim 16 , after the peeling step is completed, a step of removing the graphene remaining on the surface of the single crystal silicon carbide substrate and flattening the surface may be provided.

  This is preferable because the single crystal silicon carbide substrate once formed with graphene can be reused.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view illustrating a graphene substrate according to an embodiment of the present invention. As shown in FIG. 1, a graphene substrate 100 in the present embodiment includes a silicon substrate (hereinafter also referred to as a Si substrate) 10 corresponding to a support substrate in the present invention, a wafer-sized graphene 31, a graphene 31, and a Si substrate. 10 and amorphous silicon 20 which is an adhesive layer for adhering to 10. The Si substrate 10 and the amorphous silicon 20 are connected by a covalent bond. On the other hand, the amorphous silicon 20 and the graphene 31 are connected to a van der Waals bond or a van der Waals bond partially by a covalent bond. The graphene 31 in the graphene substrate 100 is suitable for use as a channel or wiring of a circuit element (for example, a silicon semiconductor element), a transparent electrode of a display device, or the like.

  In the present embodiment, the Si substrate 10 is used as the support substrate. However, the present invention is not limited to this. As the support substrate, for example, a material containing silicon without containing carbon, such as a quartz substrate, can be used. Thus, Si substrates and quartz substrates are cheaper and easier to process than silicon carbide substrates. Therefore, by using the Si substrate or the quartz substrate as the support substrate in this manner, a graphene substrate that is inexpensive and easy to process can be obtained.

  In the present embodiment, the amorphous silicon 20 is used as the adhesive layer. However, the present invention is not limited to this. As the adhesive layer, silicon dioxide and amorphous carbon can be used in addition to amorphous silicon. That is, at least one of amorphous silicon, silicon dioxide, and amorphous carbon can be used for the adhesive layer.

  Note that graphene is a single-layer hexagonal carbon atom that forms a two-dimensional sheet, but in this embodiment, several layers of hexagonal carbon atoms form a two-dimensional sheet. Is also included. In other words, graphene means one or several layers of graphite. In other words, in the present embodiment, a single layer hexagonal arrangement of carbon atoms forming a two-dimensional sheet is regarded as graphene.

  Here, a method for manufacturing a graphene substrate in this embodiment will be described with reference to FIGS. FIG. 2 is a cross-sectional view for explaining a method of manufacturing a graphene substrate according to an embodiment of the present invention, and is a cross-sectional view of a silicon carbide substrate. FIG. 3 is a cross-sectional view for explaining a method of manufacturing a graphene substrate according to an embodiment of the present invention, and is a cross-sectional view of a silicon carbide substrate having graphene. FIG. 4 is a cross-sectional view for explaining a method of manufacturing a graphene substrate according to an embodiment of the present invention, and is a cross-sectional view of a silicon carbide substrate on which amorphous silicon is formed. FIG. 5 is a cross-sectional view for explaining a method of manufacturing a graphene substrate according to an embodiment of the present invention, and is a cross-sectional view of a bonded silicon substrate and a silicon carbide substrate. FIG. 6 is a cross-sectional view for explaining a method of manufacturing a graphene substrate according to an embodiment of the present invention, and is a cross-sectional view of a peeled silicon substrate (graphene substrate) and a silicon carbide substrate.

  First, as shown in FIG. 2, a single crystal silicon carbide substrate (hereinafter also referred to as a SiC substrate) 30 is prepared. Then, by heating the SiC substrate 30 in a vacuum (about 1400 ° C.), the graphene 31 is formed on the surface of the SiC substrate 30 as shown in FIG. 3 (graphene forming step). Thus, when SiC substrate 30 is heated in a vacuum (about 1400 ° C.), Si is selectively sublimated to form graphene 31. Graphene 31 is formed on the Si surface of SiC substrate 30.

  Graphene 31 may be formed on the entire main surface of SiC substrate 30 or may be formed partially. In the case where the graphene 31 is formed over the entire main surface, the graphene substrate 100 having the relatively large area of the graphene 31 can be obtained, which is preferable. On the other hand, it is preferable to partially form the graphene 31 because distortion due to the difference in thermal expansion coefficient between the Si substrate 10 and the graphene 31 can be reduced.

  Further, when the graphene 31 is partially formed, it can be formed by patterning the graphene 31 by photolithography. In addition, the amorphous silicon 20 formed on the graphene 31 may be patterned before the bonding process (adhesive layer patterning process). By patterning the amorphous silicon 20 in this manner, the graphene 31 formed on the surface of the SiC substrate 30 has a portion where the amorphous silicon 20 is not removed by the patterning (that is, the amorphous silicon 20 remains on the graphene 31). Only the portion) is formed (transferred) on the Si substrate 10.

  Next, as shown in FIG. 4, the amorphous silicon 20 as an adhesive layer is deposited by sputtering (for example, about 10 nm) on the graphene 31 (Si surface) formed on the SiC substrate 30 (adhesive layer forming step). ). The amorphous silicon 20 as the adhesive layer is for adhering the Si substrate 10 and the graphene 31. In other words, the graphene 31 is transferred from the SiC substrate 30 to the Si substrate 10. Note that a defect may be introduced into at least a part of the graphene 31 (defect introduction step). By doing so, the bond between the graphene 31 and the amorphous silicon 20 can be strengthened, so that the graphene 31 can be easily formed on the Si substrate 10.

  On the other hand, the Si substrate 10 used as the support substrate is formed by forming an oxide film by a conventional method, and is subjected to carros cleaning. In the case where the Si substrate 10 is used as the support substrate as in the present embodiment, the element components (buried oxide film and doping) for forming the silicon semiconductor element are formed inside the Si substrate 10 before the bonding process. It is preferable that a region is formed. This is because it is difficult to form element components such as a buried oxide film and a doping region after the graphene 31 is formed on the Si substrate 10.

  Then, as shown in FIG. 5, the SiC substrate 30 on which the graphene 31 and the amorphous silicon 20 are formed and the Si substrate 10 after the carros cleaning are bonded (bonding step). This bonding is fixed by hydrogen bonding by the same mechanism as the conventional Si substrate bonding. Thereafter, the bonded substrates are annealed in an inert gas (about 800 ° C.) to convert hydrogen bonds to covalent bonds by a dehydrogenation reaction. By doing so, since the bond between the amorphous silicon 20 and the Si substrate 10 can be strengthened, the graphene 31 can be easily formed on the Si substrate 10.

  Then, as shown in FIG. 6, the graphene 31 formed on the SiC substrate 30 is mechanically peeled off (the peeling process) from the annealed substrates (Si substrate 10 and SiC substrate 30 bonded with the amorphous silicon 20). The graphene substrate 100 is completed by transferring to the Si substrate 10 side. The step of peeling the Si substrate 10 and the SiC substrate 30 can be done by putting a knife edge or the like between the graphene 31 and the SiC substrate 30 at the end of the substrate, for example.

  Further, a vaporized substance may be introduced between the graphene 31 and the SiC substrate 30 and peeled off due to the expansion of the vaporized substance. For example, the vaporized substance can be introduced by introducing a sulfate group by acid treatment after the graphene formation step or by ion-implanting hydrogen after the graphene formation step. Thus, it can peel easily by peeling by expansion | swelling of a vaporization substance. That is, it is preferable because the graphene 31 remaining on the SiC substrate 30 can be suppressed and the graphene 31 can be efficiently transferred to the Si substrate 10.

  Further, the bonding force (adhesion degree) between the SiC substrate 30 and the graphene 31 is smaller than the bonding force (adhesion degree) between the graphene 31 and the amorphous silicon 20 and the bonding force (adhesion degree) between the amorphous silicon 20 and the Si substrate 10. Is preferred. By satisfying such a relationship, the residual graphene 31 on the SiC substrate 30 can be suppressed.

  As described above, the SiC substrate 30 on which the graphene 31 is formed and the Si substrate 10 are bonded together via the amorphous silicon 20, and then the SiC substrate 30 is peeled off, so that the Si substrate 10 is disposed on the Si substrate 10 via the amorphous silicon 20. The graphene substrate 100 including the graphene 31 can be formed. That is, when amorphous silicon 20 is used, graphene 31 formed on the surface of SiC substrate 30 can be transferred to Si substrate 10.

  Further, wafer-sized graphene 31 can be formed on the surface of the SiC substrate 30. Therefore, a wafer-sized graphene 31 can be formed on the Si substrate 10 via the amorphous silicon 20. That is, the graphene substrate 100 having the wafer-sized graphene 31 can be formed on a supporting substrate (Si substrate 10 in the present embodiment) other than the SiC substrate 30. In other words, by bonding the graphene 31 and the Si substrate 10 with the amorphous silicon 20, the graphene substrate 100 having the wafer-sized graphene 31 can be obtained without using a silicon carbide substrate as a support substrate.

  Note that the graphene 31 may remain on the SiC substrate 30 after peeling. Therefore, after the peeling step is completed, a step of removing the graphene 31 remaining on the surface of the SiC substrate 30 by oxidation or polishing and flattening the surface may be performed. This is preferable because the SiC substrate 30 once formed with graphene can be reused.

It is sectional drawing which shows the graphene board | substrate in embodiment of this invention. It is sectional drawing according to process explaining the manufacturing method of the graphene substrate in embodiment of this invention, and is sectional drawing of a silicon carbide substrate. It is sectional drawing according to process explaining the manufacturing method of the graphene substrate in embodiment of this invention, and is sectional drawing of the silicon carbide substrate which has a graphene. It is sectional drawing according to process explaining the manufacturing method of the graphene substrate in embodiment of this invention, and is sectional drawing of the silicon carbide substrate in which the amorphous silicon was formed. It is sectional drawing according to process explaining the manufacturing method of the graphene substrate in embodiment of this invention, and is sectional drawing of the bonded silicon substrate and silicon carbide substrate. It is sectional drawing according to process explaining the manufacturing method of the graphene substrate in embodiment of this invention, and is sectional drawing of the peeled silicon substrate (graphene substrate) and silicon carbide substrate.

Explanation of symbols

10 silicon substrate (Si substrate), 20 amorphous silicon, 30 silicon carbide substrate (SiC substrate), 31 graphene, 100 graphene substrate

Claims (16)

Graphene,
A support substrate for supporting the graphene;
An adhesive layer that bonds the graphene and the support substrate;
Equipped with a,
The adhesive layer, graphene substrate, wherein the amorphous silicon or amorphous carbon Tona Rukoto. A graphene forming step of forming graphene on a surface of the single crystal silicon carbide substrate by heat-treating the single crystal silicon carbide substrate;
An adhesive layer forming step of forming an adhesive layer on the graphene;
A bonding step of bonding a support substrate to the single crystal silicon carbide substrate through the adhesive layer;
A peeling step of peeling the single crystal silicon carbide substrate from the single crystal silicon carbide substrate and the support substrate bonded together via the adhesive layer;
A method for producing a graphene substrate, comprising: Wherein in the graphene forming step, the manufacturing method of the graphene substrate of claim 2, wherein that you form the graphene entire main surface of the single crystal silicon carbide substrate. Method for manufacturing a graphene substrate of claim 3, wherein Rukoto includes a graphene patterning step of forming a surface part on the graphene of the single-crystal silicon carbide substrate. The graphene patterning step, the manufacturing method of the graphene substrate of claim 4, wherein the patterning to Rukoto the graphene by photolithography Fi. Graphene substrate according to any one of claims 2 to 5, characterized in Rukoto comprises an adhesive layer patterning step of patterning the adhesive layer formed on the graphene before the bonding step Production method. The method for producing a graphene substrate according to any one of claims 2 to 6 , further comprising a defect introduction step of introducing a defect into at least a part of the graphene. The adhesive layer, amorphous silicon, a manufacturing method of the graphene substrate according to any one of claims 2 to 7, characterized in Rukoto Do from at least one of silicon dioxide, amorphous carbon. The bonding process is, after the bonding by hydrogen bonding, by dehydrogenation reaction by heat treatment, the graphene according to any one of claims 2 to 8, characterized that you converted to covalently bond A method for manufacturing a substrate. The support substrate, the manufacturing method of the graphene substrate according to any one of the silicon substrate and quartz from at least one such said Rukoto claims 2 to the substrate 9. If the support substrate is the silicon substrate, the inside of the silicon substrate, according to claim 10, before the bonding step, characterized that you have been elements components for constituting the silicon semiconductor element is formed method for manufacturing a graphene wafer according to. The peeling The method for manufacturing a graphene substrate according to any one of claims 2 to 1 0, characterized that you mechanically delaminate the single crystal silicon carbide substrate from the supporting substrate. The stripping step, the said graphene introducing vapors between the single-crystal silicon carbide substrate, according to claim 2 or any of claims 1 1 one, characterized that you peel by the expansion of the vaporized material The manufacturing method of the graphene board | substrate as described in a term. The vapors method for manufacturing a graphene substrate of claim 13, wherein the sulfate group der Rukoto introduced in the acid treatment after the graphene forming step. The vapors method for manufacturing a graphene substrate of claim 13, wherein the hydrogen der Rukoto that ion implantation after the graphene forming step. After the stripping step is completed, the removal of the graphene remaining on the surface of the monocrystalline silicon carbide substrate, any of claims 2 to 1 5, characterized in Rukoto comprising the step of flattening the surface one The manufacturing method of the graphene board | substrate as described in a term.

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