JP2008294110A - Substrate for electronic device, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a substrate for electronic devices wherein the substrate can be manufactured through simple processes, and the adhesion force of a graphite film to the substrate is improved. <P>SOLUTION: The manufacturing method for electronic devices has a silanol-radical forming process for forming a silanol radical on the surface of a silicon substrate 1, a hydroxyl-radical forming process for forming a hydroxyl radical on the surface of a graphite film 14, and a joining process for generating a silicon-carbide bond by pressing the graphite film 14 with the hydroxyl radical onto the silicon substrate 1 with the silanol radical and heat-treating it so as to join the silicon substrate 1 and the graphite film 14 to each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electronic device substrate and a manufacturing method thereof, and more particularly to a field effect transistor substrate for manufacturing an VLSI and a manufacturing method thereof.

  With the high integration and high functionality of VLSI (Large Scale Integration), the miniaturization of transistors constituting the VLSI is progressing. According to the description of Non-Patent Document 1, it is reported that the miniaturization of transistors will change at a reduction rate of about 70% in 3 years in the next 10 or more years. At present, the minimum line width of the VLSI represented by the microprocessor unit (MPU) and the dynamic random access memory (DRAM) is mainly 65 nm to 90 nm, but in 2010, it will be 30 nm to 45 nm. Is predicted to be at the 10 nm level.

  A conventional VLSI is composed of field-effect transistors suitable for high integration with high speed and low power consumption, and is manufactured using a silicon substrate. However, a silicon field effect transistor is expected to reach a physical performance limit when the gate length is around 5 nm (see Non-Patent Document 1).

  A substrate using a graphite film as a substrate for a field effect transistor that replaces silicon has high conductivity characteristics in the same manner as a carbon nanotube that has been actively researched and developed in recent years. By using a graphite film, An increase in switching speed, which is one of the performance indexes of a field effect transistor, can be realized.

  In the future, the use of a substrate using a graphite film is expected to dramatically increase the integration and functionality of VLSI by further miniaturizing transistors.

  In order to make full use of the characteristics of this graphite film, it is necessary to reduce the thickness of the graphite film. Usually, when a thin film material is formed on a substrate, the same material having the same lattice constant as the substrate and the thin film material can be used for good bonding, and defects due to lattice mismatching do not occur. There is an advantage that the quality of the product is maintained. On the other hand, if different materials such as glass, amorphous material, sapphire, and silicon (Si) are used for the substrate, there is an advantage that it is inexpensive.

  Moreover, in order to form a thin film of a normal substance, there are many cases in which a solid phase substance is deposited from a material substance such as a gas phase on a substrate. However, it is not possible to deposit a high quality graphite thin film. It was difficult.

  On the other hand, there is a method of bonding a thin film substance to the surface of the substrate. In this case, there is an advantage that the quality of the thin film substance can be maintained even if the substrate and the thin film substance are different materials.

  As shown in FIG. 7, we bonded the graphite film 4a on the silicon substrate 1a having the silicon oxide 2a on the surface layer as the adhesion type graphite film electronic device substrate 30 as shown in FIG. We have developed a substrate with the above structure.

"Outline of ITRS 2005 Edition (International Semiconductor Technology Roadmap 2005 Edition)", JEITA Review, February 2006, p.22-25 Novoselov et al., "Electric Field Effect in Atomically Thin Carbon Films", SCIENCE, 306, 2004, p.666-669. Shigeru Fujinaga, “Molecular Orbital Method”, published by Iwanami Shoten Co., Ltd., 1st edition, September 18, 1980, p.195 Furukawa Shizujiro, “Integrated Circuit Process Technology Series SOI Structure Formation Technology”, published by Sangyo Tosho Co., Ltd., October 23, 1987, p.198 Robert O. Lussow, "The Influence of Thermal SiO2 Surface Constitution on the Adherence of Photoresists", J. Electrochem. Soc .; SOLID STATE SCIENCE, vol. 155, No. 6, June 1968, p.660-664 Ihara, Y. et al., “Oxidation treatment of carbon black with low-temperature oxygen plasma”, Color Material Association, Vol.54, No 9, 1981, p.531-536 The Chemical Society of Japan, “Organic Synthesis V -Oxidation Reaction”, Laboratory Chemistry, Maruzen Co., 4th Edition, Volume 23, 457 Mochida Isao, “Chemistry and Engineering of Carbon Materials”, Modern Applied Science Series, Volume 3, 1st Edition, Asakura Shoten Co., Ltd., September 10, 1990, p. 39

However, when the thin film material is adhered to the surface of the substrate, the following problems may occur.
(1) In order to bond the graphite film to the substrate, coating and heat treatment for forming a bonding film between them are required, and the process becomes complicated.
(2) The adhesive force of the adhesive film is weak, and the graphite film is peeled off from the substrate during the manufacture of the transistor.

  Accordingly, an object of the present invention is proposed in view of the above-described problems, and provides an electronic device substrate that can be manufactured by a simple process and has improved adhesion between the graphite film and the substrate, and a method for manufacturing the same. It is.

  An electronic device substrate manufacturing method according to the present invention that solves the above-described problems includes a silanol group forming step of forming a silanol group on the surface of a silicon substrate, a hydroxyl group forming step of forming a hydroxyl group on the surface of a graphite film, and a silanol. And a bonding step of bonding the silicon substrate and the graphite film by heat-treating the graphite film having the hydroxyl group formed on the silicon substrate on which the group is formed to generate a silicon carbide bond. .

  The method for manufacturing an electronic device substrate according to the present invention is a method for manufacturing the electronic device substrate, wherein the heat treatment in the bonding step includes a heat treatment that causes a dehydration reaction and a heat treatment that causes a deoxygenation reaction. It is characterized by that.

  The method for manufacturing an electronic device substrate according to the present invention is the above-described method for manufacturing an electronic device substrate, wherein the silanol group forming step includes a step of oxidizing the surface of the silicon substrate, and a silicon substrate having an oxidized surface. And a step of heat-treating in a steam atmosphere or a nitrogen gas atmosphere containing steam.

  The method for manufacturing an electronic device substrate according to the present invention is a method for manufacturing the electronic device substrate, wherein the hydroxyl group forming step includes a step of treating the graphite film with oxygen plasma.

  The method for manufacturing an electronic device substrate according to the present invention is a method for manufacturing the electronic device substrate, wherein a thinning step of thinning the graphite film is performed after the joining step.

  The method for manufacturing an electronic device substrate according to the present invention is the above-described method for manufacturing an electronic device substrate, wherein the thinning step is performed by etching using a chemical reaction using a gas containing ozone. .

  The method for manufacturing an electronic device substrate according to the present invention is the above-described method for manufacturing an electronic device substrate, characterized in that the thinning step is performed by etching using oxygen plasma.

  The method for manufacturing an electronic device substrate according to the present invention is the above-described method for manufacturing an electronic device substrate, wherein the thinning step is performed by etching by an oxidation reaction using oxygen gas.

  The method for manufacturing an electronic device substrate according to the present invention is the above-described method for manufacturing an electronic device substrate, wherein the thinning step uses a pressure-sensitive adhesive sheet to form one or more graphene films constituting the graphite film. It is characterized by being performed by peeling one by one.

  The method for manufacturing an electronic device substrate according to the present invention is a method for manufacturing the electronic device substrate, wherein the thinning step is performed by chemical mechanical polishing.

  An electronic device substrate according to the present invention for solving the above-described problems is an electronic device substrate manufactured by the above-described method for manufacturing an electronic device substrate.

  The electronic device substrate according to the present invention is the electronic device substrate described above, wherein the graphite film is a graphene film.

  The electronic device substrate according to the present invention is the electronic device substrate, wherein the graphite film has a thickness of 0.15 nm or more and 1 nm or less.

  According to the method for manufacturing an electronic device substrate according to the present invention, compared to the method for manufacturing an electronic device substrate including an application step of performing an application for forming an adhesion film between the substrate and the thin film substance, Since there is no coating process, it can be manufactured by a simple process. In addition, since the silicon substrate and the graphite film are directly bonded by silicon carbide bonding, the bonding force is improved as compared with the substrate for electronic devices in which an adhesive film is interposed between the silicon substrate and the graphite film. Can do.

  Below, the board | substrate for electronic devices which concerns on the best embodiment of this invention, and its manufacturing method are demonstrated concretely based on an Example.

Below, the manufacturing method of the board | substrate for electronic devices which concerns on the 1st Example of this invention is demonstrated concretely with reference to drawings.
FIG. 1 is a view for explaining a method for manufacturing an electronic device substrate according to a first embodiment of the present invention, and FIG. 2 is a schematic view of the electronic device substrate manufactured by the method.

  In this example, first, a silicon substrate 1 having a diameter of 50 mm was thermally oxidized to obtain a silicon substrate 1 having a silicon oxide film 2 formed on the surface layer (see FIG. 1A). For thermal oxidation, the method and process conditions (for example, 1000 ° C., 1 hour) currently used for the production of silicon VLSI are applied.

  Subsequently, silanol groups (Si—OH groups) were formed on the surface of the silicon substrate 1 on which the silicon oxide film 2 was formed on the surface, that is, the surface of the silicon oxide film 2 (silanol group forming step). Specifically, the surface of the silicon oxide film 2 is heat-treated at 500 ° C. for 1 hour in a nitrogen gas atmosphere made of nitrogen gas through which pure water is passed, that is, in a nitrogen gas atmosphere containing water vapor. A silanol group was formed on (see, for example, Non-Patent Document 5).

  On the other hand, in this example, a commercially available graphite film 14 (for example, FL300SH (a film having a diameter of about 50 mm and a thickness of 400 μm) manufactured by Nippon Carbon Co., Ltd.) was used. A hydroxyl group (OH group) was formed (hydroxyl group forming step) Specifically, the surface of the graphite film 14 is covered with carbon atoms, but a plasma processing apparatus (Fig. 1) equipped with a high frequency (13.56 MHz) generator. A graphite film 14 is placed in the film, and after introducing oxygen gas, a hydroxyl group is formed on the surface of the graphite film 14 by treatment in oxygen plasma generated by applying a high frequency for 2 hours (Non-Patent Document 6). reference).

  The treatment in the silanol group formation step and the hydroxyl group formation step is an example, and may be performed under other conditions (treatment time, treatment temperature).

  Subsequently, as shown in FIG. 1B, a hydroxyl group (not shown) was formed on the silicon substrate 1 having a silanol group (not shown) formed on the surface via the silicon oxide film 2. After placing the graphite film 14 in contact, while applying pressure, heat 9 is applied stepwise (heat treatment) to form a silicon carbide bond to bond the silicon oxide film 2 and the graphite film 14 of the silicon substrate 1 together. (Joining process).

  In the bonding step, a direct bonding method between silicon substrates can be applied. For example, in a silicon wafer direct bonding method for manufacturing a silicon on insulator (hereinafter referred to as SOI) substrate, silanol groups (Si—OH) formed on the surface of each silicon substrate are in stages. It is known that, through a thermal treatment, a silicon bond is formed directly by forming a Si—Si bond through hydrogen bonds and Si—O—Si bonds (see, for example, Non-Patent Document 4). By applying this bonding method, silicon carbide bonding can be generated and the silicon oxide film 2 and the graphite film 14 can be directly bonded. The silicon oxide film 2 having a silanol group and the graphite film 14 having a hydroxyl group are heat-treated stepwise while being pressurized in accordance with the silicon wafer direct bonding method, thereby directly bonding both films (Si-C bond). Can be generated). The heat treatment includes a heat treatment for causing a dehydration reaction from the silanol groups of the silicon substrate 1 and the hydroxyl group of the graphite film 14 (for example, a heat treatment for 1 hour at 200 ° C.) and a heat treatment for causing a deoxygenation reaction (for example, 1000 ° C. for 1 hour). Heat treatment). In addition, the heat processing temperature in the said joining process is one Example, You may carry out at other temperature.

  Thus, according to the present embodiment, it is possible to realize a graphite thin film that is directly formed on a silicon substrate, which could not be realized conventionally, without using an adhesive. In this embodiment, silicon is used as a substrate on which a graphite thin film is formed. Graphite is a polycrystalline or single crystal of carbon, and a covalent bond is formed between carbon and silicon of the substrate when viewed microscopically. This bond between carbon and silicon is extremely strong. Therefore, if carbon and silicon are normally bonded, the adhesion between the graphite film and the silicon substrate becomes good.

  Here, it is not easy to combine SiC and carbon into SiC, which is a high-quality crystal, because usually high energy such as heat is required. In this example, Si—C bonds, which are usually not easy to form good bonds, are formed by introducing hydroxyl groups on the surface states of silicon and carbon and introducing Si—OH and C—OH, which are intermediate states. Can be formed. That is, an electronic device substrate having a bond between silicon and carbon can be easily obtained by interposing a production reaction of an intermediate having a hydroxyl group.

  Next, the silicon substrate 1 to which the graphite film 14 is bonded is placed in an apparatus (not shown) having an ozone generator and a substrate heating heater, and as shown in FIG. The graphite film 14 was etched while being heated (thinning step). In this step, oxygen gas may be mixed into the ozone 5. In this case, ultraviolet rays may be irradiated to generate oxygen radicals that are active reactive species for graphite (carbon).

  Ozone is a strong oxidant and generally oxidizes organic compounds, but has the effect of cleaving these by reacting with carbon double bonds and benzene rings in particular (see, for example, Non-Patent Document 7). The graphite film 14 is composed of a benzene ring, and is therefore decomposed and etched by a chemical reaction with ozone.

  In an etching process based on a chemical reaction using a gas containing ozone, the etch rate depends on the ozone concentration and the reaction temperature, and the etching amount (thinning) can be controlled by the etching time. The accuracy of the remaining film thickness of the graphite film can be controlled by the etch rate. If the etch rate is reduced, the graphite film can be thinned with sub-nanometer accuracy. For example, if the etch rate can be set to 1 nm / min, it is technically possible to etch one graphene layer at a time by setting the etching time to 0.3 minutes (18 seconds).

  As described above, the residual film thickness of the graphite film 14 can be controlled at the sub-nanometer level by the etching time, and an ultra-thin film of the graphite film 4 can be obtained in the etching process (FIG. 1D )reference).

  The graphite film 4 is composed of a combination of a plurality of carbon atoms and is a planar layered material having a turtle shell shape. The graphite film 4 shows the physical properties of a semimetal in terms of material. In the case of a semimetal, unlike a semiconductor such as silicon, the field effect that enables the operation of the field effect transistor is shielded at a very short distance of 1 nm or less (for example, see Non-Patent Document 2). Therefore, in order to manufacture a field effect transistor, the thickness of the graphite film needs to be at least 1 nm or less.

  Here, the graphene film is an ultimate form of the graphite film 4 and is a graphite film composed of one carbon atom layer (the graphite film is a film in which graphene films are laminated at intervals of about 0.3 nm). The thickness of the graphene film is estimated to be about 0.15 nm from the spread of the electron cloud of carbon atoms obtained by quantum chemical calculation (see Non-Patent Document 3). Therefore, since the thickness is 1 nm or less, a field effect acts and it is possible to manufacture a field effect transistor.

  The film thickness of the obtained graphite film 4 is about 1 nm, which corresponds to three graphene films. As described above, if the graphite film is 1 nm or less, a field effect acts and a field effect transistor can be manufactured. Therefore, a direct bonding type graphite film electronic device substrate (electronic device substrate) having the graphite film 4 was manufactured according to this example.

  Specifically, as shown in FIG. 2, an electron having a silicon substrate 1 having a silicon oxide film 2 formed on the surface and a graphite film 4 bonded to one side surface of the silicon substrate 1 by silicon carbide bonding. A device substrate 20 was obtained.

  In this example, an electronic device substrate 20 having a graphite film 4 having a film thickness of about 1 nm was obtained. However, if a field effect transistor can be manufactured, even a substrate having a graphite film having another film thickness can be used. good.

  It is also technically possible to manufacture a single-layer graphene film by proceeding with the etching process more precisely.

  Further, in the present embodiment, the silicon substrate 1 having a diameter of 50 mm is used. However, the present embodiment can also be applied to a 300 mm silicon substrate that is currently mainstream in the manufacture of VLSI.

  When a field effect transistor having a gate length of 20 nm was manufactured using the graphite film having a thickness of 1 nm manufactured in this example, the switching speed was about twice that of a silicon field effect transistor having the same gate length of 20 nm. was gotten.

  Therefore, according to the method for manufacturing an electronic device substrate according to the present embodiment, a method for manufacturing an electronic device substrate including a coating process for performing an application for forming an adhesive film between the substrate and the thin film substance, and In comparison, since there is no coating process, it can be manufactured by a simple process. Further, as described above, since the silicon substrate 1 and the graphite film 4 are directly joined by silicon carbide bonding, as compared with an electronic device substrate in which an adhesion film is interposed between the silicon substrate and the graphite film. Bonding force can be improved.

  In the above description, the thermal oxidation method has been described as the method of forming the silicon oxide film 2 on the surface of the silicon substrate 1, but a method of irradiating the silicon substrate with oxygen plasma may be used. Even if such a method is used, it is possible to form a silicon oxide film on the surface of the silicon substrate.

  Moreover, in the above, in order to form a silanol group on the surface of the silicon substrate 1, the silicon substrate 1 having the silicon oxide film 2 on the surface has been described using a method of heat-treating in a nitrogen gas atmosphere containing water vapor. However, a method of heat-treating the silicon substrate in a water vapor atmosphere or a method of irradiating the silicon substrate with oxygen plasma may be used. Even if such a method is used, it is possible to form a silanol group on the surface of the silicon substrate.

  Moreover, in the above, in order to form a silanol group on the surface of the silicon substrate 1, a step of forming the silicon oxide film 2 on the surface of the silicon substrate 1, and the silicon substrate 1 on which the silicon oxide film 2 is formed are treated with water vapor. Although the explanation has been made by using the method of performing the two steps of the heat treatment in the nitrogen gas atmosphere, the silicon substrate is heat-treated in the nitrogen atmosphere containing oxygen and water vapor instead of the silanol group forming step consisting of the two steps. You may use the method of performing the process to do. Even if such a method is used, it is possible to form a silanol group on the surface of the silicon substrate.

Below, the manufacturing method of the board | substrate for electronic devices which concerns on the 2nd Example of this invention is demonstrated concretely with reference to drawings.
FIG. 3 is a view for explaining a method of manufacturing an electronic device substrate according to the second embodiment of the present invention.
The steps until the graphite film 14 is bonded to the silicon substrate 1 (FIGS. 3A to 3B) are the steps in the method for manufacturing an electronic device substrate according to the first embodiment of the present invention described above (FIG. Since this is the same as FIG. 1A to FIG.

  After the bonding step, the silicon substrate 1 to which the graphite film 14 is bonded is placed in a commercially available oxygen plasma etching apparatus (not shown), oxygen gas is introduced, and then a high frequency is applied as shown in FIG. Then, the oxygen plasma 6 was generated to etch the graphite film 14 (thinning step).

  In the thinning step, the etching rate depends on the flow rate and pressure of oxygen gas, the high frequency power to be applied, and the substrate temperature, and the etching amount (thinning) can be controlled by the etching time. Further, the accuracy of the remaining film thickness of the graphite film can be controlled by the etch rate in the same manner as the manufacturing method of the electronic device substrate according to the first embodiment described above. It is possible to reduce the thickness of the graphite film.

  The residual film thickness of the graphite film 14 can be controlled at the sub-nanometer level by the etching time as described above, as in the method for manufacturing the electronic device substrate according to the first embodiment described above. In FIG. 3, an ultrathin film of the graphite film 4 was obtained (see FIG. 3D).

  The film thickness of the obtained graphite film 4 is about 1 nm, which corresponds to three graphene films. As described above, if the graphite film is 1 nm or less, a field effect acts and a field effect transistor can be manufactured. Therefore, an electronic device substrate having a graphite film was manufactured according to this example.

  In this example, a substrate having a graphite film 4 with a film thickness of about 1 nm was obtained. However, a substrate having a graphite film with another film thickness may be used as long as a field effect transistor can be manufactured.

  In addition, it is technically possible to manufacture a substrate having a single graphene film layer by further precisely performing the etching in the thinning step.

  Further, in this embodiment, the silicon substrate 1 having a diameter of 50 mm is used, but this embodiment can also be applied to a silicon substrate having a diameter of 300 mm, which is currently mainstream in the manufacture of VLSI.

  Therefore, according to the method for manufacturing an electronic device substrate according to the present embodiment, a method for manufacturing an electronic device substrate including a coating process for performing an application for forming an adhesive film between the substrate and the thin film substance, and In comparison, since there is no coating process, it can be manufactured by a simple process. Further, as described above, since the silicon substrate 1 and the graphite film 4 are directly joined by silicon carbide bonding, as compared with an electronic device substrate in which an adhesion film is interposed between the silicon substrate and the graphite film. Bonding force can be improved.

Below, the manufacturing method of the board | substrate for electronic devices which concerns on the 3rd Example of this invention is demonstrated concretely with reference to drawings.
FIG. 4 is a diagram for explaining a method for manufacturing an electronic device substrate according to a third embodiment of the present invention.
The steps (FIGS. 4A to 4B) until the graphite film 14 is bonded to the silicon substrate 1 are the steps in the method for manufacturing the electronic device substrate according to the first embodiment of the present invention described above (FIG. Since this is the same as FIG. 1A to FIG.

  After the bonding step, heat 19 at 450 ° C. is applied to the silicon substrate 1 to which the graphite film 14 is bonded in an atmosphere of oxygen gas 7, so that the graphite film 14 becomes oxygen gas 7 as shown in FIG. (Etching process).

In the etching in the thinning step, the etching rate depends on the flow rate and pressure of oxygen gas and the reaction temperature, and the etching amount (thinning) can be controlled by the etching time. The graphite film is resistant to 400 ° C. in an oxygen atmosphere, but is oxidized and etched when heated to 400 ° C. or higher. Further, the accuracy of the remaining film thickness of the graphite film can be controlled by the etch rate in the same manner as the manufacturing method of the electronic device substrate according to the first embodiment described above. It is possible to reduce the thickness of the graphite film. The graphite film is removed as carbon dioxide (CO ₂ ) by an oxidation reaction.

  The residual film thickness of the graphite film 14 can be controlled at the sub-nanometer level by the etching time as described above, as in the method for manufacturing the electronic device substrate according to the first embodiment described above. Thus, an ultra-thin film of the graphite film 4 could be obtained (see FIG. 4D). The graphite film 14 is removed as carbon dioxide 8.

  The film thickness of the obtained graphite film 4 is about 1 nm, which corresponds to three graphene films. As described above, if the graphite film is 1 nm or less, a field effect acts and a field effect transistor can be manufactured. Therefore, an electronic device substrate having a graphite film was manufactured according to this example.

  In this example, a substrate having a graphite film 4 with a film thickness of about 1 nm was obtained. However, a substrate having a graphite film with another film thickness may be used as long as a field effect transistor can be manufactured.

  In addition, it is technically possible to manufacture a substrate having a single graphene film layer by further precisely performing the etching in the thinning step.

  Further, in this embodiment, the silicon substrate 1 having a diameter of 50 mm is used, but this embodiment can also be applied to a silicon substrate having a diameter of 300 mm, which is currently mainstream in the manufacture of VLSI.

  Therefore, according to the method for manufacturing an electronic device substrate according to the present embodiment, a method for manufacturing an electronic device substrate including a coating process for performing an application for forming an adhesive film between the substrate and the thin film substance, and In comparison, since there is no coating process, it can be manufactured by a simple process. Further, as described above, since the silicon substrate 1 and the graphite film 4 are directly joined by silicon carbide bonding, as compared with an electronic device substrate in which an adhesion film is interposed between the silicon substrate and the graphite film. Bonding force can be improved.

Below, the manufacturing method of the board | substrate for electronic devices which concerns on the 4th Example of this invention is demonstrated concretely with reference to drawings.
FIG. 5 is a diagram for explaining a method of manufacturing an electronic device substrate according to a fourth embodiment of the present invention.
The steps until the graphite film 14 is bonded to the silicon substrate 1 (FIGS. 5A to 5B) are the steps in the method for manufacturing the electronic device substrate according to the first embodiment of the present invention described above (FIG. Since this is the same as FIG. 1A to FIG.

  After the bonding step, the pressure-sensitive adhesive sheet 10 having the same shape as the shape of the graphite film 14 (a circle having a diameter of 50 mm) is adhered to the graphite film 14, and then the pressure-sensitive adhesive sheet is fixed while fixing the silicon substrate 1 as shown in FIG. 10 was pulled upward (thinning step).

  In the peeling step (thinning step) with the pressure-sensitive adhesive sheet, the graphite film is peeled off when the peeling force (adhesive strength) of the pressure-sensitive adhesive sheet is greater than the bonding force between the layers of the graphite film. It has been reported that the minimum stress required for exfoliation of the graphite film is about 0.4 MPa (for example, see Non-Patent Document 8). Therefore, the graphite film can be peeled off by using an adhesive sheet having an adhesive strength of 0.4 MPa or more.

  At this time, as described above, since the adhesive force of the adhesive sheet 10 to the graphite film 14 is larger than the bonding force between the layers of the graphite film 14, the graphite film 14b adheres to the adhesive sheet 10 as shown in the figure. The graphite film 14a was peeled off. By repeating this peeling step, the graphite film 4 could be thinned (see FIG. 5D). In this case, since the unit to be exfoliated is inefficient for each graphene film, in actuality, a notch for promoting the exfoliation start is provided at a desired position in the thickness direction of the graphite film 14a, and a plurality of graphene films Were peeled at once.

  The film thickness of the obtained graphite film 4 is about 1 nm, which corresponds to three graphene films. As described above, if the graphite film is 1 nm or less, a field effect acts and a field effect transistor can be manufactured. Therefore, an electronic device substrate having a graphite film was manufactured according to this example.

  In this example, a substrate having a graphite film 4 with a film thickness of about 1 nm was obtained. However, a substrate having a graphite film with another film thickness may be used as long as a field effect transistor can be manufactured.

  In addition, it is technically possible to manufacture a single-layered graphene film by proceeding more precisely in the thinning step.

  Further, in this embodiment, the silicon substrate 1 having a diameter of 50 mm is used, but this embodiment can also be applied to a silicon substrate having a diameter of 300 mm, which is currently mainstream in the manufacture of VLSI.

  Therefore, according to the method for manufacturing an electronic device substrate according to the present embodiment, a method for manufacturing an electronic device substrate including a coating process for performing an application for forming an adhesive film between the substrate and the thin film substance, and In comparison, since there is no coating process, it can be manufactured by a simple process. Further, as described above, since the silicon substrate 1 and the graphite film 4 are directly joined by silicon carbide bonding, as compared with an electronic device substrate in which an adhesion film is interposed between the silicon substrate and the graphite film. Bonding force can be improved.

Below, the manufacturing method of the board | substrate for electronic devices which concerns on the 5th Example of this invention is demonstrated concretely with reference to drawings.
FIG. 6 is a diagram for explaining a method of manufacturing an electronic device substrate according to a fifth embodiment of the present invention.
The steps (FIGS. 6A to 6B) until the graphite film 14 is bonded to the silicon substrate 1 are the steps in the method for manufacturing an electronic device substrate according to the first embodiment of the present invention described above (FIG. Since this is the same as FIG. 1A to FIG.

  After the bonding step, an appropriate amount of the polishing agent 11 is dropped on the polishing pad 12, and the polishing pad 12 is pressed while pressing the graphite film 14 adhered to the silicon substrate 1 onto the polishing pad 12, as shown in FIG. The graphite film 14 was polished by rotating (chemical mechanical polishing (chemical / mechanical polishing (CMP): thinning step)).

  In the thinning step, the polishing rate depends on the type of abrasive, the pressure of the graphite film against the polishing pad, and the rotation speed of the polishing pad, and the polishing amount (thinning) is controlled by the polishing time (polishing time). Can do. The CMP technology is currently capable of polishing at the sub-nanometer level, and therefore, the graphite film can be thinned with sub-nanometer level accuracy. CMP is a general-purpose technology that is currently widely used in planarization processes in silicon wafer manufacturing and VLSI manufacturing processes, and can be easily applied to the present invention.

  As described above, the film thickness accuracy of the remaining film of the graphite film 14 can be controlled at the sub-nanometer level, and an ultra-thin film of the graphite film 4 can be obtained in the polishing step (FIG. 6D). )reference).

  The film thickness of the obtained graphite film 4 is about 1 nm, which corresponds to three graphene films. As described above, if the graphite film is 1 nm or less, a field effect acts and a field effect transistor can be manufactured. Therefore, an electronic device substrate having a graphite film was manufactured according to this example.

  In this example, a substrate having a graphite film 4 with a film thickness of about 1 nm was obtained. However, a substrate having a graphite film with another film thickness may be used as long as a field effect transistor can be manufactured.

  In addition, it is technically possible to manufacture a substrate having a single graphene film layer by further precisely polishing in the thinning step.

  Further, in this embodiment, the silicon substrate 1 having a diameter of 50 mm is used, but this embodiment can also be applied to a silicon substrate having a diameter of 300 mm, which is currently mainstream in the manufacture of VLSI. In this case, it is possible to use a CMP manufacturing apparatus used in a wafer manufacturing process or a VLSI manufacturing process.

  Therefore, according to the method for manufacturing an electronic device substrate according to the present embodiment, a method for manufacturing an electronic device substrate including a coating process for performing an application for forming an adhesive film between the substrate and the thin film substance, and In comparison, since there is no coating process, it can be manufactured by a simple process. Further, as described above, since the silicon substrate 1 and the graphite film 4 are directly joined by silicon carbide bonding, as compared with an electronic device substrate in which an adhesion film is interposed between the silicon substrate and the graphite film. Bonding force can be improved.

  As mentioned above, although five embodiments from the first embodiment to the fifth embodiment have been described with respect to the present invention, the method for manufacturing an electronic device substrate according to the present invention may be performed independently. Alternatively, a plurality of embodiments may be combined.

It is a figure for demonstrating the manufacturing method of the board | substrate for electronic devices which concerns on the 1st Example of this invention. It is a schematic diagram of the board | substrate for electronic devices which concerns on the 1st Example of this invention. It is a figure for demonstrating the manufacturing method of the board | substrate for electronic devices which concerns on the 2nd Example of this invention. It is a figure for demonstrating the manufacturing method of the board | substrate for electronic devices which concerns on the 3rd Example of this invention. It is a figure for demonstrating the manufacturing method of the board | substrate for electronic devices which concerns on the 4th Example of this invention. It is a figure for demonstrating the manufacturing method of the board | substrate for electronic devices which concerns on the 5th Example of this invention. It is a schematic diagram of the board | substrate for electronic devices using the conventional graphite film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Silicon oxide film 4, 14, 14a, 14b Graphite film 5 Ozone 6 Oxygen plasma 7 Oxygen gas 8 Carbon dioxide 9, 19 Heat 10 Adhesive sheet 11 Polishing agent 12 Polishing pad 20 Direct bonding type graphite film Electronic device substrate 30 Adhesive Graphite Film Electronic Device Substrate

Claims (13)

A silanol group forming step of forming a silanol group on the surface of the silicon substrate;
A hydroxyl group forming step for forming hydroxyl groups on the surface of the graphite film;
A bonding step of bonding the silicon substrate and the graphite film by heat-treating a graphite film having a hydroxyl group formed on a silicon substrate having a silanol group while pressurizing the silicon film to form a silicon carbide bond. A method of manufacturing an electronic device substrate. A method for manufacturing an electronic device substrate according to claim 1, comprising:
The heat treatment in the bonding step includes a heat treatment that causes a dehydration reaction and a heat treatment that causes a deoxygenation reaction. A method of manufacturing an electronic device substrate according to claim 1 or 2,
The silanol group forming step includes a step of oxidizing the surface of the silicon substrate and a step of heat-treating the silicon substrate having the oxidized surface in a water vapor atmosphere or a nitrogen gas atmosphere containing water vapor. A method of manufacturing an electronic device substrate. A method for manufacturing an electronic device substrate according to any one of claims 1 to 3,
The method for producing a substrate for an electronic device, wherein the hydroxyl group forming step includes a step of treating the graphite film with oxygen plasma. A method for manufacturing an electronic device substrate according to any one of claims 1 to 4,
A method for manufacturing an electronic device substrate, comprising performing a thinning step of thinning the graphite film after the joining step. A method for manufacturing an electronic device substrate according to claim 5, comprising:
The method for manufacturing a substrate for an electronic device, wherein the thinning step is performed by etching by a chemical reaction using a gas containing ozone. A method for manufacturing an electronic device substrate according to claim 5, comprising:
The method of manufacturing a substrate for an electronic device, wherein the thinning step is performed by etching using oxygen plasma. A method for manufacturing an electronic device substrate according to claim 5, comprising:
The method of manufacturing a substrate for an electronic device, wherein the thinning step is performed by etching by an oxidation reaction using oxygen gas. A method for manufacturing an electronic device substrate according to claim 5, comprising:
The method for producing a substrate for an electronic device, wherein the thinning step is performed by peeling one or more graphene films constituting the graphite film using an adhesive sheet. A method for manufacturing an electronic device substrate according to claim 5, comprising:
The method of manufacturing a substrate for an electronic device, wherein the thinning step is performed by chemical mechanical polishing. 11. An electronic device substrate manufactured by the method for manufacturing an electronic device substrate according to claim 1. The electronic device substrate according to claim 11, comprising:
The substrate for an electronic device, wherein the graphite film is a graphene film. An electronic device substrate according to claim 11 or claim 12,
The thickness of the said graphite film is 0.15 nm or more and 1 nm or less, The board | substrate for electronic devices characterized by the above-mentioned.

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