JP6501538B2 - Method of manufacturing nano carbon base material - Google Patents

Description

  The present invention relates to a method of producing a nanocarbon substrate and a nanocarbon substrate.

  As a method of synthesizing nanocarbons such as carbon nanotubes (hereinafter referred to as "CNT"), an arc discharge method, a laser evaporation method, a CVD method and the like are conventionally known. In recent years, a so-called SiC surface decomposition method has been proposed in which a SiC substrate is heated at high temperature in vacuum to remove silicon (Si) atoms from the substrate and obtain carbon nanocarbon by remaining carbon (C) atoms. It is reported that the surface of the SiC crystal is changed to the Si removed layer by the SiC surface decomposition method, and a nanotube film composed of a large number of CNTs oriented in the thickness direction is obtained on this SiC removed layer (for example, patent) Reference 1).

During heating in vacuum in the SiC surface decomposition method, a mask is used to cover and protect a predetermined region of the surface of the SiC substrate, thereby limiting the region from which Si atoms are removed. Since nanocarbon selectively grows on the exposed portion of the surface of the SiC substrate, a patterned nanocarbon film is obtained in the thickness direction of the SiC substrate of the substrate between the surface and the back surface of the SiC substrate. For example, it has been reported that a patterned CNT film is formed using a Si ₃ N ₄ film as a mask (for example, Non-Patent Document 1). In addition, it has been reported that a pattern of a CNT film is formed by protecting a predetermined region on the surface of a SiC wafer with a carbon film (C film) to suppress a CNT growth region (for example, non-patent document) 2).

Patent No. 3183845 gazette

Michiko Kusunoki et al., “Patterned Carbon Nanotube Films Formed by Surface Decomposition of SiC Wafers”, Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L1486-1488 Z. Goknur Cambaz et al., "Nanocatalytic synthesis of carbon nanotubes, graphene and graphite on SiC", Carbon, 46 (2008), p. 841-849

  A nanocarbon film such as a CNT film or the like formed and patterned in the thickness direction of the SiC substrate can be used as an electrode or the like in a SiC power device. In order to apply to such applications, a nanocarbon base material from which the mask on the surface of the SiC substrate is removed is required without damaging the selectively grown nanocarbon.

In order to selectively grow nanocarbon and obtain a patterned nanocarbon film in the thickness direction of the SiC substrate, Si ₃ N ₄ film and C film are used as a mask. Both the Si ₃ N ₄ film and the C film have resistance to protect the SiC substrate from high temperature heating in vacuum. However, the present inventors have found that these films are difficult to selectively remove from the surface of the SiC substrate without damaging the nanocarbon.

For example, to remove the Si ₃ N ₄ film from the SiC substrate surface, treatment with a relatively high concentration of phosphoric acid is required. This phosphoric acid is expected to cause considerable damage to the nanocarbon. On the other hand, the C film can not be selectively removed with respect to nanocarbon. When the C film as a mask is to be removed from the surface of the SiC substrate, nanocarbon selectively grown on a predetermined region of the SiC substrate is also removed. For this reason, a patterned nanocarbon film can not be obtained.

  Therefore, the present invention has a selectively grown, substantially damage-free nanocarbon in the thickness direction of the SiC substrate, and a method of manufacturing a nanocarbon substrate applicable to a SiC power device, and a selectively grown substantially It is an object of the present invention to provide a nanocarbon base material which has nanocarbon without damage in the thickness direction of the SiC substrate and can be applied to a SiC power device.

  The method for producing a nanocarbon substrate according to the present invention is a method for producing a nanocarbon substrate in which nanocarbon is formed in a nanocarbon-forming region on a SiC substrate, and is sequentially stacked on the SiC substrate. Forming a mask layer that includes the peeling layer and the heat-resistant layer, and at least the heat-resistant layer defines the nanocarbon-forming region of the SiC substrate, and heating the SiC substrate on which the mask layer is formed; The method is characterized by comprising the steps of: forming nanocarbon in the nanocarbon-forming area by removing Si from the nanocarbon-forming area; and removing the mask layer from the surface of the SiC substrate.

  The nanocarbon substrate according to the present invention is a nanocarbon substrate in which nanocarbon is formed in a nanocarbon formation region on a SiC substrate, and the SiC substrate includes a nonnanocarbon formation region and the nanocarbon non-formation region. And the nanocarbon is grown in the thickness direction of the SiC substrate from the bottom surface of the nanocarbon formation region, and the G band and the D band in the Raman spectrum are included. And the peak intensity ratio (G / D ratio) thereof is 0.6 or more.

  According to the present invention, the mask layer having the heat-resistant layer is provided on the SiC substrate (hereinafter, also simply referred to as a substrate) to protect the area of the substrate covered by the mask layer while the nano not covered by the mask layer In the carbon formation region, nanocarbon is formed in the thickness direction of the substrate between the front surface and the back surface of the substrate. The mask layer includes a peeling layer and a heat-resistant layer which are sequentially stacked. Because the exfoliation layer is present between the substrate and the heat-resistant layer, the mask layer having the heat-resistant layer is easily removed from the substrate. By this, it is possible to manufacture a nanocarbon base material which has selectively grown, substantially damage-free nanocarbon in the thickness direction of the substrate and can be applied to a SiC power device.

It is sectional drawing explaining the structure of the nanocarbon base material of this invention. It is sectional drawing which shows the manufacturing method of the nanocarbon base material which concerns on 1st Embodiment of this invention in steps, FIG. 2A is the stage which formed the peeling layer on a SiC substrate, FIG. 2B is a peeling layer and a heat-resistant layer FIG. 2C is a view showing the step of forming nanocarbon on the SiC substrate, and FIG. 2D showing the step of removing the mask layer from the surface of the SiC substrate. It is an electron micrograph before heat processing of the SiC substrate which has a exfoliation layer and a heat-resistant layer. It is the electron micrograph after heat processing of the SiC substrate shown in FIG. It is an electron micrograph of the nanocarbon base material obtained by removing a peeling layer from the SiC substrate shown in FIG. It is a Raman spectrum acquired about the nano carbon base material of this invention. It is sectional drawing which shows the manufacturing method of the nanocarbon base material based on 2nd Embodiment of this invention in steps, FIG. 7A is the stage which formed the sacrificial layer on the SiC substrate surface, FIG. 7B is the surface of a sacrificial layer and a SiC substrate. 7C shows the step of removing the sacrificial layer and obtaining the mask layer on the surface of the SiC substrate, FIG. 7D shows the step of forming nanocarbon on the SiC substrate, and FIG. 7E shows the step of forming the mask layer. Is a diagram showing the stage of removing the surface of the SiC substrate from the surface of the substrate.

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

1. First embodiment (whole configuration)
The nanocarbon base material which concerns on 1st Embodiment of this invention is demonstrated with reference to FIG.

  The nanocarbon base material 30 of this invention is equipped with CNT20 as a nanocarbon formed in the nanocarbon formation area 10b of the SiC substrate 10, as shown in FIG. In the nanocarbon substrate 30 of the present invention, the CNTs 20 are selectively formed in a predetermined region (nanocarbon formation region 10b) of the surface of the SiC substrate 10.

  The SiC substrate 10 includes a nanocarbon non-formation region 10a and a nanocarbon formation region 10b recessed from the surface of the nanocarbon non-formation region 10a. In the nanocarbon formed region 10b in which the CNTs 20 are formed, Si is removed from the SiC substrate 10, so the nanocarbon formed region 10b is recessed from the surface of the nonnanocarbon formed region 10a. In the nanocarbon substrate 30 of the present invention, the CNTs 20 are grown in the thickness direction of the SiC substrate 10 from the bottom surface 11 of the nanocarbon formation region 10 b between the front surface and the back surface of the SiC substrate 10. The bottom surface 11 of the nanocarbon formed region 10 b in which the CNTs 20 are grown is the (000-1) plane (C plane) of the SiC substrate 10.

  In the nanocarbon substrate 30 of the present invention, the CNTs 20 formed in the nanocarbon formation region 10b have a peak intensity ratio (G / D ratio) of G band to D band in the Raman spectrum of 0.6 or more. The height h of the CNTs 20 depends on the growth conditions, but is generally about 3 to 500 nm, for example, about 200 nm. The height of the CNTs 20 can be confirmed by transmission electron microscope (TEM) observation. In addition, the CNTs 20 selectively formed in the nanocarbon formation region 10b can be referred to as a patterned CNT film. It is confirmed by an atomic force microscope (AFM) that the surface roughness of the patterned CNT film is about 5 nm.

(Production method)
The manufacturing method of the nanocarbon base material which concerns on 1st Embodiment of this invention is demonstrated with reference to FIG.

  In the method of manufacturing the nanocarbon substrate 30 according to the first embodiment, first, as shown in FIG. 2A, the peeling layer 12 is formed on the entire surface of the SiC substrate 10. Next, as shown in FIG. 2B, the heat-resistant layer 14 is formed in a predetermined region of the release layer 12, and the mask layer 16 having a laminated structure of the release layer 12 and the heat-resistant layer 14 is formed on the non-nanocarbon formed region 10a. The heat-resistant layer 14 defines the nanocarbon-forming region 10 b of the SiC substrate 10. Thereafter, the SiC substrate 10 having the mask layer 16 is heated, and as shown in FIG. 2C, the peeling layer 12 on the nanocarbon formation region 10b of the SiC substrate 10 is removed to form the nanocarbon formation region 10b of the SiC substrate 10. The CNTs 20 are formed as nanocarbons. Finally, the mask layer 16 was removed from the surface of the SiC substrate 10 to expose the non-nanocarbon formed region 10a, and the CNTs 20 were selectively grown on the nanocarbon formed region 10b of the SiC substrate 10 as shown in FIG. 2D. The nanocarbon substrate 30 of the present invention is obtained.

  Each process shown in FIGS. 2A to 2D will be described in detail below.

  First, as shown in FIG. 2A, the peeling layer 12 is formed on the entire (000-1) plane (C plane) of the SiC substrate 10. The SiC constituting the SiC substrate 10 is not particularly limited, and examples thereof include 4H-SiC and 6H-SiC.

The release layer 12 is formed of a metal oxide that is soluble in a specific liquid. The specific liquid is a liquid that does not substantially damage the CNTs 20 formed in the nanocarbon forming region 10b of the SiC substrate 10 in the later step. In the present specification, the fact that the CNTs are not substantially damaged means that the Raman shift (G / D ratio, peak wave number, half width) of the CNTs does not change, that is, the defect amount of the CNTs is not increased. It means that. The metal oxide used to form the peeling layer 12, for example _{ZnO, Ga 2 O 3, Y} 2 O 3, ZrO 2, and HfO ₃ are exemplified. The method for forming the release layer 12 is not particularly limited. If the peeling layer 12 of a predetermined thickness can be formed on the entire surface of the SiC substrate 10, the peeling layer 12 can be formed by any method. For example, in the case of forming the peeling layer 12 using ZnO, a liquid phase method using any material can be adopted.

  The thickness of the release layer 12 formed here is preferably about 1 to 3 μm. If it is peeling layer 12 having a thickness of about 1 to 3 μm, when heated, the portion covered with heat resistant layer 14 does not substantially change and the SiC substrate not covered with heat resistant layer 14 The portion on the ten nanocarbon formation regions 10b can be removed.

  As shown in FIG. 2B, a heat-resistant layer 14 is formed in a predetermined region on the peeling layer 12 formed on the entire surface of the SiC substrate 10. The peeling layer 12 and the heat-resistant layer 14 sequentially stacked constitute the mask layer 16 of the nanocarbon non-forming region 10a. The heat-resistant layer 14 on the upper side of the mask layer 16 defines the nanocarbon formation region 10 b of the SiC substrate 10.

  Heat-resistant layer 14 is formed of a high melting point material that can protect SiC substrate 10 from heating. Covering with the heat-resistant layer 14 also protects the underlying release layer 12 from heating. The high melting point material used to form the heat resistant layer 14 can be selected from, for example, the group consisting of C, W, Ta, Re, and Os. For example, C layer as the heat resistant layer 14 is formed by depositing C in a predetermined region of the peeling layer 12 by, for example, a focused ion beam (FIB) to form the heat resistant layer 14, thereby forming nanocarbons of the SiC substrate 10. Region 10b can be defined.

  By heating performed in a later step, a part of the metal oxide forming the heat-resistant layer 14 may be sublimated to reduce the thickness of the heat-resistant layer 14. If the thickness is too small, the heat-resistant layer 14 can not sufficiently function to protect the underlying release layer 12 and the SiC substrate 10. The heat-resistant layer 14 having a thickness of 100 nm or more does not completely disappear, for example, even when it is subjected to heat treatment at 1600 ° C. for 1 hour. The heat-resistant layer 14 having a thickness of 100 nm or more can maintain the thickness necessary to protect the underlying release layer 12 and the SiC substrate 10 during the heat treatment. Even if the heat-resistant layer 14 is formed to be excessively thick, no particular effect can be obtained. If the thickness of the heat-resistant layer 14 is at most about 300 nm, the underlying peeling layer 12 and the SiC substrate 10 can be protected during heat treatment at 1600 ° C. for 1 hour.

  As shown in FIG. 2B, in the SiC substrate 10, the surface of the nanocarbon formed region 10b is covered with the peeling layer 12. On the other hand, the nanocarbon non-forming area 10 a excluding the nanocarbon forming area 10 b is covered with the mask layer 16 having a laminated structure of the peeling layer 12 and the heat-resistant layer 14.

By heating the SiC substrate 10 having the mask layer 16, as shown in FIG. 2C, the nanocarbon formation region 10b of the SiC substrate 10 is exposed, and the CNT 20 as nanocarbon is formed from the bottom surface 11 of the nanocarbon formation region 10b. Be done. The pressure at this time can be in the range of about 10 ⁻⁶ to 10 ⁻¹ Pa, and the heating temperature can be in the range of about 1400 to 1700 ° C. Although heating time can be suitably set according to a pressure range or heating temperature, generally it is about 5 minutes-3 hours.

  The heating can be performed, for example, by irradiating the SiC substrate 10 having the mask layer 16 with a continuously oscillated YAG laser beam. The YAG laser beam can be irradiated to an approximately central portion of the nanocarbon formation region 10b of the SiC substrate 10 with an area of, for example, about 0.2 to 3 mm.

For example, by heating at 1 × 10 ⁻² Pa or less at 1600 ° C. for 1 hour, the metal oxide forming the exfoliation layer 12 is sublimated on the nanocarbon formation region 10 b of the SiC substrate 10. This part of the peeling layer 12 is removed. At this time, the portion of the release layer 12 covered by the heat-resistant layer 14 does not substantially change. In the nanocarbon-formed region 10b of the SiC substrate 10 exposed by removing the peeling layer 12, the SiC is decomposed to remove Si. The CNTs 20 shown in FIG. 2C are formed from the surface of the SiC substrate 10 to the inside as the removal of Si proceeds. As a result, the CNTs 20 with excellent linearity can be obtained at a high density in the nanocarbon-forming region 10b.

  Thereafter, mask layer 16 is selectively removed with respect to SiC substrate 10 to expose the surface of nanocarbon non-forming region 10a of SiC substrate 10 as shown in FIG. 2D. The mask layer 16 can be easily removed from the surface of the SiC substrate 10 by dissolving the peeling layer 12. In order to dissolve the exfoliation layer 12, a liquid which does not substantially damage the CNTs 20 is used. For example, the ZnO layer as the release layer 12 can be dissolved by treatment with a 1 to 35% HCl solution for 1 second to 3 hours. Thus, the mask layer 16 can be selectively removed from the surface of the SiC substrate 10 to obtain the nanocarbon substrate 30 of the present invention in which the CNTs 20 are selectively grown on the SiC substrate 10.

(Action and effect)
In the method of manufacturing the nanocarbon substrate 30 according to the present embodiment, the non-nanocarbon formed region 10 a of the SiC substrate 10 is protected by the mask layer 16 and heated. Thereby, the CNTs 20 are selectively grown on the nanocarbon formation region 10 b of the SiC substrate 10. The mask layer 16 for protecting the nanocarbon non-formation region 10a of the SiC substrate 10 has a laminated structure of the lower peeling layer 12 and the upper heat-resistant layer 14, and the upper heat-resistant layer 14 protects the SiC substrate 10 from heating. High melting point material.

  On the other hand, the lower release layer 12 is formed of a metal oxide soluble in a liquid that does not substantially damage the CNTs 20. The metal oxide used here does not combine with the SiC constituting the substrate 10 even when heated. Therefore, according to the method of the first embodiment, the heat resistant layer 14 is separated from the SiC substrate 10 by the peeling layer 12 until the mask layer 16 including the heat resistant layer 14 is removed from the surface of the SiC substrate 10 . As described above, the material forming the release layer 12 is soluble in a liquid that does not substantially damage the selectively grown CNTs 20. For this reason, after the CNTs 20 are formed, the mask layer 16 including the heat-resistant layer 14 can be removed without substantially damaging the CNTs 20 by dissolving the peeling layer 12 with a predetermined liquid.

  Thus, the method of the first embodiment can be used to obtain the nanocarbon base material 30 of the present invention having the selectively grown substantially damage-free CNTs 20 in the thickness direction of the SiC substrate 10.

  Below, the specific example which manufactured the nano carbon base material 30 by the method shown in FIG. 2 is shown. First, the peeling layer 12 and the heat-resistant layer 14 were formed on the surface of the SiC substrate 10 to define the nanocarbon formation region 10b of the SiC substrate 10 as shown in FIG. 2B. As the peeling layer 12, a ZnO layer (2.4 μm thick) was formed on the entire C surface of the SiC substrate 10 by a liquid phase method. As the heat-resistant layer 14, a C layer having a predetermined thickness was formed in a predetermined region of the peeling layer 12 by FIB. An electron micrograph of the SiC substrate 10 provided with the peeling layer 12 and the heat-resistant layer 14 in this manner is shown in FIG.

As shown in FIG. 3, heat-resistant layers 14 _{c 1} , 14 _{c 2} , 14 _{c 3} , 14 _{c 4} , 14 _{c 6} and 14 _{c 9} are provided in predetermined regions of the peeling layer 12 covering the entire surface of the SiC substrate 10. The thicknesses of the heat resistant layers 14 _c1 , 14 _c2 , 14 _c3 , 14 _c4 , 14 _c6 , and 14 _c9 are 100 nm, 200 mn, 300 nm, 400 nm, 600 nm, and 900 nm, respectively. In FIG. 3, the region where the peeling layer 12 is exposed corresponds to the nanocarbon formed region 10 b of the SiC substrate 10. The region where the heat-resistant layers 14 _{c 1} , 14 _{c 2} , 14 _{c 3} , 14 _{c 4} , 14 _{c 6} and 14 _{c 9} are provided on the release layer 12 corresponds to the nanocarbon non-formed region 10 a of the SiC substrate 10.

Thus, the SiC substrate 10 having the heat-resistant layer 14 formed on the release layer 12 is subjected to heat treatment at 10 ^-2 Pa or less and 1600 ° C. for 1 hour, and as shown in FIG. Formed as a nanocarbon. The electron micrograph of the SiC substrate 10 after the heat treatment is shown in FIG.

As shown in FIG. 4, after the heat treatment, the peeling layer 12 does not exist in the nanocarbon formed region 10 b, and the CNTs 20 are confirmed in this region. The heat-resistant layers 14 _{c 1} , 14 _{c 2} , 14 _{c 3} , 14 _{c 4} , 14 _{c 6} and 14 _{c 9} remain even after the heat treatment, although there is a loss in part, and the nanocarbon non-forming region 10 a of the SiC substrate 10 is It is presumed that it was protected.

After the CNTs 20 are formed, they are treated with a 3% HCl solution for 3 seconds to dissolve the ZnO layer as the release layer 12 and remove the heat-resistant layers 14 _{c 1} , 14 _{c 2} , 14 _{c 3} , 14 _{c 4} , 14 _{c 6} , 14 _{c 9} Then, as shown in FIG. 2D, the surface of the nanocarbon non-forming region 10a of the SiC substrate 10 was exposed. FIG. 5 shows an electron micrograph of the nanocarbon substrate 30 thus obtained. The regions protected by the heat-resistant layers 14 _{c 1} , 14 _{c 2} , 14 _{c 3} , 14 _{c 4} , 14 _{c 6} and 14 _{c 9} are the nanocarbon non-formed regions 10 a ₁ , 10 a ₂ , 10 a ₃ , 10 a ₄ , 10 a ₆ and 10 a _{9 respectively.} As shown in FIG. If the heat-resistant layer remains after the heat treatment, the presence of SiC is recognized in these nanocarbon non-formation regions 10a ₁ , 10a ₂ , 10a ₃ , 10a ₄ , 10a ₆ , 10a ₉ so that protection from the heat treatment is It was confirmed that it was done.

The Raman spectrum of CNT 20 thus formed is shown as curve c _{0 in} FIG. In FIG. 6, curve _{c 1} is the result obtained for nano-carbon non-formation region 10a ₁ having a C layer of 100nm thick as a heat-resistant layer _{14 c1,} curve _{c 3} is a 300nm thick as a heat-resistant layer _{14 c3} the results obtained for the nano-carbon non-formation region 10a ₃ having a C layer. Curve a and curve b are shown as reference. Specifically, the curve a is a Raman spectrum of the CNT formed on the SiC substrate by the same heat treatment as described above without forming the mask layer, and the curve b is a Raman spectrum of the SiC substrate before the heat treatment is there.

In the curve a, a peak of the G band of CNTs is confirmed near 1590 cm ⁻¹ , and a peak of the D band of CNTs is confirmed near 1300 cm ⁻¹ . In this case, the peak intensity ratio (G / D ratio) between the G band and the D band is about 0.9. In general, it is known that nanocarbons such as CNTs have less damage and higher quality as the G / D ratio in the Raman spectrum is higher. If the G / D ratio is 0.6 or more, it can be said that the CNT is substantially free of damage.

When the G / D ratio is 0.5 or less, the CNTs are damaged. For example, after the CNT with _{the Si} 3 _{N 4} film as a mask is selectively grown on the SiC substrate, a _{the Si} 3 _{N 4} film on the SiC substrate is removed by phosphoric acid, in the Raman spectrum obtained for CNT on SiC substrate The G / D ratio is 0.5 or less.

Also in the curve _{c 0,} similarly to the curves a, confirmed a peak of G-band of the CNT in the vicinity of 1590 cm ^-1, a peak of D-band of the CNT is confirmed in the vicinity of 1300 cm ^-1. The peak intensity ratio (G / D ratio) between the G band and the D band is about 0.9. Since the G / D ratio in the Raman spectrum is 0.6 or more, it can be seen that the obtained CNT 20 has substantially no damage.

In the curve b shown for the SiC substrate before heat treatment, a SiC peak appears in the vicinity of 1500 to 1900 cm ⁻¹ . The peak of the CNT G band (in the vicinity of 1590 cm ⁻¹ ) and the peak of the CNT D band (in the vicinity of 1300 cm ⁻¹ ) are not confirmed in the curve b.

Curve _{c 1,} also in the curves _{c 3,} similar to the curve b, which appears is SiC peak near 1500~1900cm ^-1, G-band peak (1590 cm around ^-1) of CNT, and CNT of D band peak ( 1300 cm ^-1 ) is not confirmed.

Since the shapes of the curve c ₁ and the curve c ₃ are the same as the shape of the curve b, providing the heat-resistant layer 14 protects the SiC substrate 10 from heat treatment and avoids decomposition of SiC in this region. Recognize. As described above, when the C layer is formed as the heat-resistant layer 14, it was also confirmed that the SiC substrate 10 therebelow can be protected almost reliably if the thickness of the C layer is 100 nm or more.

2. Second Embodiment The nanocarbon substrate 30 as described above can also be manufactured by the method according to the second embodiment. The manufacturing method of the nanocarbon base material 30 which concerns on 2nd Embodiment is demonstrated with reference to FIG.

(Production method)
In the method of manufacturing the nanocarbon substrate 30 according to the second embodiment, first, as shown in FIG. 7A, the sacrificial layer 22 is formed on the surface of the nanocarbon formation region 10b of the SiC substrate 10. Next, as shown in FIG. 7B, the peeling layer 24 and the heat-resistant layer 26 are sequentially formed on the surface of the sacrificial layer 22 and the SiC substrate 10. Thereafter, the sacrificial layer 22 is removed to obtain a mask layer 28 having a laminated structure of the release layer 24 and the heat-resistant layer 26 as shown in FIG. 7C on the non-nanocarbon formed region 10a. The nanocarbon formation region 10b of the SiC substrate 10 is defined. Furthermore, the SiC substrate 10 having the mask layer 28 is heated to form CNTs 20 as nanocarbon in the nanocarbon formation region 10b of the SiC substrate 10 as shown in FIG. 7D. Finally, the mask layer 28 is removed from the surface of the SiC substrate 10 to expose the non-nanocarbon formed region 10a, thereby selectively growing the CNTs 20 on the nanocarbon formed region 10b of the SiC substrate 10 as shown in FIG. 7E. The inventive nanocarbon substrate 30 is obtained.

  In the first embodiment described above, the peeling layer 12 on the surface of the nanocarbon formation region 10b of the SiC substrate 10 is removed by heating to expose the nanocarbon formation region 10b, but in the second embodiment, The surface of the nanocarbon formed region 10b is already exposed upon heating. Except for this point, the method for producing a nanocarbon substrate according to the second embodiment is basically the same as the method for producing a nanocarbon substrate according to the first embodiment.

  Each process shown to FIG. 7A-FIG. 7E is demonstrated in detail below.

  First, as shown in FIG. 7A, the sacrificial layer 22 is formed on the nanocarbon formation region 10b of the SiC substrate 10. This sacrificial layer 22 is to be removed in a later step in order to form a mask layer 28 which defines the nanocarbon formation region 10b. For these applications, the sacrificial layer 22 is formed with a thickness greater than or equal to that of the resulting mask layer 28. For example, the sacrificial layer 22 can be formed to be about 5 μm. As the sacrificial layer 22, for example, a resist pattern formed by a general method using any resist material can be used.

  Next, as shown in FIG. 7B, the peeling layer 24 and the heat-resistant layer 26 are sequentially formed on the entire surface of the SiC substrate 10 on which the sacrificial layer 22 is formed. The peeling layer 24 and the heat-resistant layer 26 can be formed with the same thickness using the material as described in the first embodiment. However, in the second embodiment, the formation of the peeling layer 24 and the heat-resistant layer 26 is performed at a temperature at which the sacrificial layer 22 is not damaged. In the manufacturing method of the second embodiment, the formation temperature of the peeling layer 24 and the heat-resistant layer 26 is lower than that of the first embodiment, and can be appropriately set according to the material of the sacrificial layer 22.

  In the second embodiment, an ion beam sputtering method, a resistance heating evaporation method, an electron beam evaporation method, or the like can be employed to form the peeling layer 24 and the heat-resistant layer 26. When forming a ZnO layer as the exfoliation layer 24, it may be deposited by the same liquid phase method as in the first embodiment.

  After the release layer 24 and the heat-resistant layer 26 are sequentially formed, the sacrificial layer 22 is removed together with the portion of the release layer 24 and the heat-resistant layer 26 over the sacrificial layer 22. The sacrificial layer 22 can be dissolved and removed by, for example, an organic solvent. As a result, as shown in FIG. 7C, a mask layer 28 composed of the remaining portions of the peeling layer 24 and the heat-resistant layer 26 is formed on the surface of the nanocarbon non-forming region 10 a of the SiC substrate 10. The mask layer 28 defines the nanocarbon formation region 10 b of the SiC substrate 10.

  Next, the SiC substrate 10 on which the mask layer 28 is formed is heated. The conditions at this time can be the same as in the first embodiment. By heat treatment, in the Si removal region 10 a of the SiC substrate 10, SiC is decomposed to remove Si. The CNTs 20 shown in FIG. 7D are formed from the surface of the SiC substrate 10 to the inside as the removal of Si proceeds.

  In the subsequent steps, the mask layer 28 is removed from the surface of the SiC substrate 10 by dissolving the peeling layer 12 in the same manner as in the first embodiment, thereby exposing the nanocarbon non-formation region 10a. Thus, as shown in FIG. 7E, the nanocarbon substrate 30 of the present invention in which the CNTs 20 are selectively grown on the SiC substrate 10 can be obtained.

(Action and effect)
In the method according to the second embodiment, as in the first embodiment, the nanocarbon non-formation region 10a of the SiC substrate 10 is protected by the mask layer 28 and heated to form the CNT 20 in the nanocarbon formation region 10b of the SiC substrate 10 Selective growth. The mask layer 28 in the second embodiment has a laminated structure of the peeling layer 24 and the heat-resistant layer 26 as in the first embodiment, and the material of the peeling layer 24 and the heat-resistant layer 26 is the same as that in the first embodiment. Is used, and the same effect as that of the first embodiment can be obtained.

  The mask layer 28 in the method according to the second embodiment is formed in a predetermined region of the SiC substrate 10 using the sacrificial layer 22. Because the sacrificial layer 22 is present, the formation of the mask layer 28 including the release layer 24 and the heat-resistant layer 26 is generally performed at a low temperature. Moreover, in the mask layer 28, not only the heat-resistant layer 26 but also the peeling layer 24 is patterned. The method according to the second embodiment is advantageous in that no impurities are attached to the selectively grown CNTs 20.

  Thus, the method of the second embodiment can provide the nanocarbon base material 30 of the present invention having the substantially grown, damage-free CNTs 20 in the thickness direction of the SiC substrate 10.

3. Modified Example The present invention is not limited to the above embodiment, and can be appropriately modified within the scope of the present invention. In the first embodiment, the heat-resistant layer 14 is formed in a predetermined region of the peeling layer 12 using FIB to define the nanocarbon-formed region 10b of the SiC substrate 10, but the heat-resistant layer 14 is formed by another method You may For example, the heat-resistant layer 14 is formed on the entire surface of the release layer 12 by a resistance heating evaporation method or the like, and the nano-carbon forming region 10 b of the SiC substrate 10 can be defined by patterning this.

In addition, when the peeling layer 12 is formed using ZnO, it has been described that the peeling layer 12 is dissolved and the mask layer 16 is removed using an HCl solution, but depending on the type of the material forming the peeling layer 12 The liquid used for dissolution and removal may be selected appropriately. For example, the exfoliation layer 12 formed using Ga ₂ O ₃ can be dissolved with an acid such as HCl or a base such as NaOH. The release layer 12 formed using Y ₂ O ₃ , ZrO ₂ , or HfO ₂ can be dissolved in HF.

  Furthermore, in the above embodiment, the case where the SiC substrate whose predetermined region is protected by the mask layer is heated to remove Si from the C surface side of the SiC substrate to selectively grow CNT as nanocarbon has been described. When a predetermined region of the (0001) surface (Si surface) of the SiC substrate is protected by the same mask layer, graphene can be selectively grown as nanocarbon.

In the case of selectively growing graphene, heating can be performed in a wider temperature range than in the case of forming CNTs. Specifically, the heating temperature can be 1100 to 1600 ° C., for example, 1400 ° C. In addition, the pressure for selectively growing graphene can be approximately the same as that of CNT, but may be heated at atmospheric pressure. In the case of selectively growing graphene, a pressure range of about 10 ⁻⁶ to 10 ⁶ Pa can be applied.

  By using the method of the present invention, it is also possible to obtain a nanocarbon base material having selectively grown, substantially damage-free graphene in the thickness direction of the SiC substrate.

DESCRIPTION OF SYMBOLS 10 SiC substrate 10a Nanocarbon non-formation area | region 10b Nanocarbon formation area 12, 24 Peeling layer 14, 26 Heat-resistant layer 16, 28 Mask layer 20 CNT (nanocarbon)
22 Sacrifice layer 30 Nano carbon substrate

Claims (3)

A method for producing a nanocarbon substrate, wherein nanocarbon is formed in a nanocarbon formation region on a SiC substrate,
Forming a mask layer including a peeling layer and a heat-resistant layer sequentially stacked on the SiC substrate, and defining at least the heat-resistant layer the nanocarbon-forming region of the SiC substrate;
Forming nanocarbon in the nanocarbon formed region by heating the SiC substrate having the mask layer formed thereon and removing Si from the nanocarbon formed region;
Removing the mask layer from the surface of the SiC substrate ,
The release layer is formed of a metal oxide that is soluble in a liquid that does not substantially damage the nanocarbon, and the metal oxide includes ZnO, Ga ₂ O ₃ , Y ₂ O ₃ , ZrO ₂ , and Selected from HfO ₃
The heat-resistant layer is formed of a high melting point material capable of protecting the SiC substrate from the heating in the step of forming nanocarbon in the nanocarbon formation region, and the high melting point material includes C, W, Ta, Re, and A method of producing a nanocarbon base material characterized by being selected from Os . The mask layer is
Forming the release layer on the entire surface of the SiC substrate;
It forms by covering the surface of the said exfoliation layer with the above-mentioned heat-resistant layer except on the above-mentioned nanocarbon formation field,
The method according to claim 1, wherein the release layer on the nanocarbon-formed region is removed by the heating. The mask layer is
Forming a sacrificial layer on the surface of the nanocarbon formation region;
The release layer and the heat-resistant layer are sequentially formed on the surface of the sacrificial layer and the surface of the SiC substrate,
The method according to claim 1, wherein the sacrificial layer is formed by removing the sacrificial layer together with the release layer and the heat-resistant layer on the sacrificial layer.

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