JP2011195397A - Cvd apparatus for forming carbon nanotube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vapor deposition apparatus which can obtain carbon nanotubes grown in a desired shape even on a substrate coated with a catalyst all over.SOLUTION: The CVD apparatus for forming carbon nanotubes has a heating chamber 13 in which the substrate K coated with the catalyst is disposed and which can keep a predetermined degree of vacuum, wherein a raw material gas G is supplied to the substrate K and carbon nanotubes are grown by a thermochemical vapor growth method. The CVD apparatus includes a plurality of gas guide duct bodies 23 for leading the raw material gas G to carbon nanotube formation ranges of the substrate K and a plurality of gas introduction pipes 5 the one end of each of which is connected to each gas guide duct body 23 to introduce the raw material gas G into the gas guide duct body 23.

Description

  The present invention relates to a CVD apparatus for forming carbon nanotubes.

  In a CVD apparatus for forming carbon nanotubes, it is necessary to apply a catalyst in advance to a location where carbon nanotubes are grown on a substrate. For example, the catalyst is applied on the entire surface of the substrate by a roll coater method.

  As an example of such an apparatus, there is known a carbon nanotube manufacturing apparatus that grows carbon nanotubes using plasma on a substrate coated with a catalyst (for example, Patent Document 1).

  In this carbon nanotube production apparatus, a liquid containing a catalytic metal is sprayed on the substrate surface by spraying to form a thin film, on which a raw material gas is supplied and plasma is generated, whereby carbon nanotubes are formed on the thin film. It is something to grow.

JP 2005-67916 A

  However, in the carbon nanotube manufacturing apparatus, since the liquid containing the catalyst metal is sprayed onto the substrate by spraying without limiting the application range, a thin film made of the catalyst metal is formed on the entire surface of the substrate. Moreover, since carbon nanotubes grow on this thin film, they grow on the entire surface of the substrate.

  For this reason, the carbon nanotubes are grown in a desired shape at a plurality of locations on the substrate, that is, patterning cannot be performed, and the carbon nanotubes are grown at unnecessary locations, resulting in waste.

On the other hand, in order to perform patterning, it is difficult to apply the catalyst by limiting the range rather than the entire surface of the substrate by a wet method such as a spray method.
Accordingly, an object of the present invention is to provide a vapor deposition apparatus capable of obtaining carbon nanotubes grown in a desired shape even on a substrate on which a catalyst is applied on the entire surface.

In order to solve the above-mentioned problems, a CVD apparatus for forming carbon nanotubes according to claim 1 of the present invention has a vacuum container that can arrange a substrate coated with a catalyst inside and maintain a predetermined degree of vacuum. , A CVD apparatus for forming carbon nanotubes that grows carbon nanotubes by supplying a source gas to the substrate by thermal chemical vapor deposition,
A plurality of ducts for introducing the source gas to the carbon nanotube generation range of the substrate, and a plurality of gas introduction pipes each having one end connected to each of the ducts to guide the source gas to the ducts.

  The carbon nanotube forming CVD apparatus according to claim 2 is the carbon nanotube forming CVD apparatus according to claim 1, wherein a discharge path for discharging the surplus of the source gas is provided on the upper surface of the duct. It is.

  Further, the carbon nanotube forming CVD apparatus according to claim 3 is the carbon nanotube forming CVD apparatus according to claim 1 or 2, wherein the flow rate adjusting means of the source gas is provided in each gas introduction pipe. It is.

  According to the above-described CVD apparatus for forming carbon nanotubes, a plurality of ducts for guiding the source gas are provided in the carbon nanotube generation range of the substrate. Obtainable.

It is a typical perspective view which shows schematic structure of the CVD apparatus for carbon nanotube formation which concerns on Example 1 of this invention. It is principal part sectional drawing which shows schematic structure of the CVD apparatus. It is AA sectional drawing in FIG. 2 of the CVD apparatus.

Hereinafter, a carbon nanotube forming CVD apparatus according to an embodiment of the present invention will be described based on specific examples.
In this embodiment, a carbon nanotube forming CVD apparatus using a thermal CVD apparatus will be described.

  In this example, as a substrate for forming carbon nanotubes, a stainless steel sheet, that is, a stainless steel sheet (an example of a sheet material, for example, a foil material having a thickness of about 20 to 300 μm is used, It can also be referred to as a stainless steel foil.In the case of a plate material, a material having a thickness of about 300 μm to several mm is used. Long ones, that is, strips are used. Therefore, this stainless steel plate is wound around a roll, and when forming carbon nanotubes, the carbon nanotubes are continuously formed by being pulled out from this roll, and the stainless steel plate on which the carbon nanotubes are formed It is intended to be wound on a roll. That is, a stainless steel plate is pulled out from one unwinding roll, carbon nanotubes are formed (generated) on the surface of the pulled stainless steel plate, and then the stainless steel plate on which the carbon nanotubes are formed is wound on the other winding roll. Has been.

Hereinafter, a thermal CVD apparatus for forming carbon nanotubes on the surface of the above-described strip-shaped stainless steel plate (hereinafter, mainly referred to as a substrate) will be described.
As shown in FIG. 1, the thermal CVD apparatus includes a heating furnace 1 in which an elongated processing space for forming carbon nanotubes is provided in a furnace body 2. The processing space provided in is partitioned (divided) into a plurality of, for example, five rooms by partition walls 3 arranged at predetermined intervals.

  That is, in the furnace body 2, a stainless steel plate, that is, a substrate supply chamber 11 in which an unwinding roll 16 on which the substrate K is wound is disposed, and the substrate K drawn from the unwinding roll 16 is guided to the surface thereof. A pretreatment chamber 12 for performing pretreatment, a heating chamber (which can also be called a reaction chamber) 13 for guiding the substrate K pretreated in the pretreatment chamber 12 to form carbon nanotubes on the surface thereof, A post-processing chamber 14 for guiding the substrate K on which the carbon nanotubes are formed in the heating chamber 13 and performing post-processing, and a winding roll 17 for winding the substrate K that has been post-processed in the post-processing chamber 14 are provided. A substrate recovery chamber (also referred to as a product recovery chamber) 15 is provided. The rotational axes of the rolls 16 and 17 are horizontal, so that the substrate K drawn (guided) into the heating chamber 13 moves in a horizontal plane, and carbon nanotubes are placed on the surface of the substrate K. To be formed. Hereinafter, the direction between the rolls 16 and 17, that is, the direction in which the substrate K moves is referred to as the front-rear direction, and the direction orthogonal to the front-rear direction on the horizontal plane is referred to as the left-right direction.

  In the pretreatment chamber 12, the surface of the substrate K, particularly the surface that forms the carbon nanotubes (the carbon nanotube generation surface, which will be described later, here is the bottom surface), the passivation film coating, and the carbon nanotube generation The catalyst fine particles, specifically, iron fine particles (metal fine particles) are applied. For cleaning, alkali cleaning or UV ozone cleaning is used. In addition, as a method for applying the passive film, a roll coater or LPD is used. As a method for applying the catalyst fine particles, sputtering, vacuum deposition, roll coater or the like is used.

In the post-processing chamber 14, the cooling of the substrate K and the inspection of the carbon nanotubes formed on the surface, that is, the lower surface of the substrate K are performed.
In the substrate recovery chamber 15, a protective film is attached to the upper surface (back surface) of the substrate K, and the substrate K, which is a stainless steel plate to which the protective film is attached, is taken up by the take-up roll 17. The reason why the protective film is attached to the upper surface of the substrate K is to protect the carbon nanotubes formed on the substrate K wound around the outer side when the substrate K is wound up.

  As described above, five chambers are formed in the furnace body 2 by the partition walls 3. Naturally, each partition wall 3 has a communication opening (also referred to as a slit) through which the substrate K can pass. 3a is formed.

  By the way, in the heating chamber 13, carbon nanotubes are formed (generated) by a thermal CVD method. Naturally, the inside is maintained at a predetermined degree of vacuum (negative pressure state) and is used for generating carbon nanotubes. Gas, that is, raw material gas G is supplied, and consideration is given so that this raw material gas G does not leak into an adjacent room. For example, in the heating chamber 13, the raw material gas G is supplied from below together with an inert gas N such as nitrogen gas and is discharged (pulled out) from above. In addition to the heating chamber 13, that is, the substrate supply chamber 11, the pretreatment chamber 12, the posttreatment chamber 14, and the product recovery chamber 15, an inert gas N such as nitrogen gas is supplied from below and from above. Once exhausted (withdrawn), the air is prevented from entering.

Here, the heating chamber 13 will be described in detail.
That is, as shown in FIGS. 2 and 3, gas introduction for supplying a source gas G containing carbon (for example, acetylene gas is used) G to the center position in the left-right direction of the bottom wall portion 2 a of the heating chamber 13. A plurality of pipes 5 are provided at predetermined intervals in the front-rear direction so as to pass through the bottom wall part 2a from below, and a gas flow rate adjusting valve ( 9) which is an example of the flow rate adjusting means. In addition, a plurality of gas discharge ports (for example, discharge pipes) 6 for discharging gas are formed in the upper portion of the heating chamber 13 at predetermined intervals in the front-rear direction. A heat insulating material 4 having a predetermined thickness is attached to the inner wall surface that forms the heating chamber 13. Further, a gas collecting chamber 8 is formed between the upper wall portion 2 b and the heat insulating material 4 to guide the gas from each gas discharge port 6 and discharge it from one gas discharge port 7. The gas outlet 7 is provided on the upper wall 2b of the furnace body 2. Accordingly, the upper wall portion 2b, or the upper wall portion 2b and the upper heat insulating material 4 can be referred to as the upper portion of the heating chamber 13, and the bottom wall portion 2a or the bottom wall portion 2a and the lower heat insulating material 4 are heated. It can be said that the lower part of the chamber 13.

Further, although not shown, the heating chamber 13 is connected to an exhaust device (also a vacuum device) for exhausting the air in the heating chamber 13 to bring it under a predetermined reduced pressure.
An upper position of the intermediate portion in the heating chamber 13 (an upper position of the substrate in the tube forming chamber) includes a plurality of columnar (or rod-shaped) heating elements 22 for heating the heating chamber 13. A heating device 21 is provided. In addition, a non-metallic resistance heating element is used as the heating element 22, and specifically, silicon carbide, molybdenum silicide, lanthanum chromite, zirconia, graphite, or the like is used. In particular, silicon carbide and molybdenum silicide are used in a nitrogen gas or hydrogen gas atmosphere, lanthanum chromite is used only in the air, and graphite is used in an inert gas atmosphere (reducing atmosphere).

  The heating chamber 13 is provided with a plurality of gas guiding duct bodies 23 for guiding the source gas G supplied from the gas introduction pipe 5 to the substrate K in the front-rear direction. Specifically, a raw material gas (for example, between the bottom wall portion 2a of the heating chamber 13 and the substrate K, more precisely, between the lower heat insulating material 4 and the substrate K and at the upper end of each gas introduction pipe 5 is provided. Side view for guiding G to the substrate K) is a hopper shape (inverted trapezoidal shape) and the opening shape of the top surface is rectangular (the front-rear direction is the long side) The gas guide duct bodies 23 are respectively attached. In addition, in the rectangular opening formed on the upper surface of the gas guiding duct body 23, as shown in FIG. 3, a discharge passage 25 for discharging the surplus of the source gas G is directed from the short side toward the left and right. Provided. The connection between the gas guiding duct body 23 and the gas introduction pipe 5 is detachable. For example, as shown in FIGS. 2 and 3, the connection formed on the bottom surface of the gas guiding duct body 23. The opening 24 is fitted into the upper end portion of the gas introduction pipe 5. A baffle plate (also referred to as a gas dispersion plate) 27 for dispersing the source gas G is horizontally supported (arranged) by a plurality of support members 28 at an intermediate position in the height direction of the gas guiding duct body 23. Yes. In FIG. 1, the support member 28 is omitted.

  Further, on the upper surface of each gas guiding duct body 23 just below the substrate K, a rectifying plate 26 having a large number of small holes capable of pressure control is arranged. Quartz glass and ceramics having a number of holes of about 5 to 20 mm are used.

Further, in order to eliminate the influence of organic gas, the constituent material other than the substrate K in the heating chamber 13, for example, the heat insulating material 4, is made of an inorganic material such as silicon dioxide (SiO ₂ ) or aluminum dioxide (Al ₂ O ₃ ). Has been.

Here, the process in the pretreatment chamber 12 will be described.
In the pretreatment chamber 12, after the substrate K is washed, a passive film such as silica or alumina is applied, and further, for example, catalyst fine particles of metal such as iron (Fe) are applied on the upper surface of the passive film. . Of course, although not shown, in the pretreatment chamber 12, there are provided a cleaning means for the substrate K, a means for applying a passive film, and a means for applying catalyst fine particles of metal such as iron (Fe). Since it has a simple structure without a mask or the like, the passive film and the catalyst fine particles are applied to the entire surface of the substrate K.

  By the way, as the substrate K, a thin stainless steel plate (also a stainless steel foil) that has been rolled to a thickness of 20 to 300 μm and wound in a coil shape is used. Since there is a tensile residual stress in the winding direction, the substrate K warps due to the release of the residual stress during atomization of the catalyst and thermal CVD. In order to prevent such warpage, a mechanism for applying tension in the coil winding direction, specifically, tension is generated between the unwinding roll and the winding roll (for example, rotation of both rolls). The tension is generated by changing the speed, specifically, the one motor may be pulled and the other motor may be used to exhibit the brake function.) The substrate K may be pulled. Further, a weight may be provided on the winding roll side and pulled.

Next, the heating device 21 will be described.
The heating device 21 is disposed on the upper surface (back surface) side of the sheet-like substrate K, and as described above, the cylindrical heating element 22 is parallel (parallel) to the left-right direction and to the front-rear direction. Are arranged at predetermined intervals. Note that the plane including the heating elements 22 is naturally parallel to the substrate K.

  Since the heating element 22 has a cylindrical shape and is arranged in parallel at predetermined intervals, the heating to the substrate K by the heating element 22 is made uniform, that is, the temperature is uniformed. Maximization is desired. That is, the arrangement of the heating element 22 and the distance from the center of the heating element 22 to the substrate K are required to be appropriately arranged (that is, designed).

By the way, when the thermal CVD method is performed in the heating furnace 1, the inside of the heating chamber 13 is depressurized to a predetermined pressure.
This reduced pressure value is maintained in the range of several Pa to 1000 Pa. For example, it is maintained at several tens Pa to several hundred Pa. The lower limit of the reduced pressure range of several Pa is a limit value for maintaining the carbon nanotube formation rate (deposition rate), and the upper limit of 1000 Pa is a limit value in terms of soot and tar suppression. is there. Moreover, as a component member in the heating furnace 1, a non-metallic material is used so that generation | occurrence | production of soot, tar, etc. is not accelerated | stimulated.

  By the way, although the processing chambers other than the heating chamber 13, that is, the substrate supply chamber 11, the preprocessing chamber 12, the postprocessing chamber 14, and the product recovery chamber 15 have not been described in detail, these chambers 11, 12, 14 are not described. , 15 are also in a reduced pressure state, and in order to prevent gas such as air that adversely affects the formation of carbon nanotubes from flowing into the heating chamber 13, as shown in FIG. Is provided with a gas supply port 5 'for supplying an inert gas such as nitrogen gas, and the upper wall 2b is provided with a gas discharge port (also a gas discharge port) 6'.

FIG. 1 shows a schematic configuration of a thermal CVD apparatus, and the side wall portion on the near side and the heat insulating material 4 are omitted so that the inside thereof can be understood.
Next, a method for forming carbon nanotubes using the thermal CVD apparatus will be described.

  First, the substrate K is pulled out from the unwinding roll 16, and the communication openings 3 a of the partition walls 3 in the pretreatment chamber 12, the heating chamber 13, and the posttreatment chamber 14 are inserted, and the leading ends thereof are wound around the winding roll 17. Make it. At this time, a tension is applied to the substrate K so as to form a straight horizontal plane.

  Then, after the substrate K is cleaned in the pretreatment chamber 12, a passive film is applied over the entire lower surface, and iron fine particles are applied (attached) to the surface of the passive film. The application range of the catalyst fine particles may be at least the carbon nanotube formation surface (generation surface). However, since the application means has a simple structure, the application range of the catalyst fine particles is the entire lower surface.

  After this pretreatment, the substrate K is taken up by the take-up roll 17 by a predetermined length, that is, by a length for forming the carbon nanotube. Therefore, the portion where the pretreatment is performed in the pretreatment chamber 12 is sequentially moved onto each rectifying plate 26 in the heating chamber 13.

In the heating chamber 13, the exhaust device (not shown) is maintained under a predetermined reduced pressure, for example, within a range of several Pa to 1000 Pa, specifically, several tens Pa to several hundred Pa as described above. .
Then, the temperature of the substrate K is heated to a predetermined temperature, for example, 700 to 800 ° C. by the heating device 21, that is, the heating element 22, and the outer wall temperature of the heating chamber 13 is 80 ° C. or lower (preferably 50 ° C. or lower). To be.

  When the above temperature is reached, acetylene gas (C2H2) is supplied as a source gas from the gas supply port 5 to cause a predetermined reaction to generate (grow) carbon nanotubes on the lower surface of the substrate K.

  Then, when a predetermined time passes and a carbon nanotube having a predetermined height is obtained, the substrate K is similarly moved by a predetermined length, and the substrate K on which the carbon nanotube is formed is moved into the post-processing chamber 14.

In the post-processing chamber 14, the substrate K is cooled and inspected.
When this post-processing is completed, the substrate K is moved into the product recovery chamber 15, and a protective film is attached to the upper surface of the substrate K, and the substrate K is taken up by the take-up roll 17. That is, the substrate K on which the carbon nanotubes are formed is collected as a product. When all the substrates K on which the carbon nanotubes are formed are taken up by the take-up roll 17, they are taken out to the outside.

  According to the configuration of the thermal CVD apparatus, when the substrate K is introduced into the heating chamber 13 and the raw material gas G is introduced to form carbon nanotubes on the surface, the substrate K wound around the unwinding roll 16 is wound. Since the carbon nanotubes are wound around the take-up roll 17 and the carbon nanotubes are formed on the surface of the substrate K in the middle thereof, the carbon nanotubes can be continuously formed on the substrate K although each predetermined length. Therefore, the carbon nanotubes can be formed efficiently compared to the case of forming the carbon nanotubes in a complete batch type.

  In addition, since a plurality of gas guiding duct bodies 23 are provided in the heating chamber 13, carbon nanotubes can be formed within a necessary generation range. That is, in the conventional thermal CVD apparatus, the carbon nanotubes are wasted on the entire surface of the substrate K, that is, unnecessary portions.

  Further, the flow rate of the raw material gas G supplied to each gas guiding duct body 23 can be adjusted by the gas flow rate adjusting valve 9 provided in the gas introduction pipe 5, and the raw material gas G is dispersed by the baffle plate 27. The air is rectified by the rectifying plate 26 and is uniformly guided to the opening formed on the upper surface of the gas guiding duct 23. The surplus of the raw material gas G is discharged from the discharge path 25 provided in the opening. Therefore, the carbon nanotubes can be generated uniformly and appropriately regardless of the amount of the source gas G.

  In addition, since the heating element 22 is arranged on the upper surface side opposite to the carbon nanotube formation surface of the substrate K, the reaction by the source gas G is smoothly performed. This is because the heating element 22 directly warms the substrate K and the source gas G is supplied from the surface opposite to the heating element 22, so that the source gas G is supplied to the substrate K first and gas decomposition occurs in the vicinity of the substrate K. Because it occurs. When the source gas G passes through the heating element 22, gas is decomposed in the vicinity thereof, soot is easily generated at a location where the temperature changes from a high temperature to a low temperature, and carbon supplied to the substrate is reduced. End up.

  Furthermore, since the inside of the heating chamber 13 is depressurized, the diffusibility of the source gas G is improved (excellent), so that the source gas G can be supplied uniformly over the entire surface of the substrate K, in other words, the flow of the gas Since it is less susceptible to influence, it leads to an improvement in product quality, and it is possible to form carbon nanotubes even on complicated shapes and complicated free surfaces such as curved surfaces as long as catalyst particles are attached to the substrate K. .

  In the above embodiment, the gas guide duct body 23 having a rectangular opening shape has been described. In addition, a gas guide duct body having an opening shape adapted to the required carbon nanotube production range is used for replacement. And a gas guide duct body having an appropriate opening shape may be selected in accordance with a required generation range. In addition, as the gas guide duct body for replacement, for example, the opening shape is circular, elliptical, square or the like. Thereby, since the carbon nanotube can be generated in a more complicated range, even if the required generation range of the carbon nanotube is complicated, it is possible to sufficiently cope with it.

  On the other hand, in the said Example, although both rolls 16 and 17 were arrange | positioned in the horizontal direction, they can also be arrange | positioned, for example in a perpendicular direction. By doing in this way, the bending by the dead weight of the board | substrate K which arises when arrange | positioning in a horizontal direction is lose | eliminated, and the wrinkles by the thickness of the slight width direction between rolls and the board | substrate K do not generate | occur | produce. Furthermore, since it can be installed straight in the vertical direction by its own weight, there is also an advantage that plastic deformation due to wave wrinkles of the substrate K after heating does not occur.

K substrate 1 heating furnace 5 gas introduction pipe 9 gas flow rate adjusting valve 13 heating chamber 16 unwinding roll 17 winding roll 21 heating device 22 heating element 23 gas guiding duct body 25 discharge path 26 rectifying plate 27 baffle plate 28 support member

Claims (3)

A carbon nanotube which has a vacuum container capable of maintaining a predetermined degree of vacuum while arranging a substrate coated with a catalyst, and supplying a source gas to the substrate by thermal chemical vapor deposition to grow carbon nanotubes A CVD apparatus for forming,
A plurality of ducts for introducing a raw material gas into the carbon nanotube generation range of the substrate; and a plurality of gas introduction pipes each having one end connected to each of the ducts for guiding the raw material gas to the respective ducts. CVD device for forming carbon nanotubes.   The CVD apparatus for forming carbon nanotubes according to claim 1, wherein a discharge path for discharging a surplus of the source gas is provided on the upper surface of the duct. The CVD apparatus for forming carbon nanotubes according to claim 1 or 2, wherein a flow rate adjusting means for the source gas is provided in each gas introduction pipe.

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