JPS6353271A - Method and device for coating thin film - Google Patents

Abstract

PURPOSE:To simultaneously and uniformly coat a thin film on the inner and outer faces of a material to be treated by heating the tubular material to be treated to a specified temp., and supplying a gaseous reactant onto the inner and outer faces of the material to be treated from the regions which are separated and distributed to grow a thin film. CONSTITUTION:An outer pipe 16 having many dispersedly bored holes 20 on the inner face and an inner pipe 24 having many dispersedly bored holes 26 on the outer face are arranged in the form of a coaxial double pipe in a cylindrical vacuum vessel 12 to be evacuated by an evacuation device 28, and a cylindrical heater 14 is further provided on the outside of the outer pipe 16. The cylindrical material 22 to be treated such as a long-sized pipe is inserted between both pipes 16 and 24, and heated by the heater 14 to a specified temp. The gaseous reactant G is supplied into the cavity 18 of the outer pipe 16 and the inner pipe 24 from the respective gas supply sources 30 and 32, and blown against the inner and outer faces of the material 22 to be treated from the holes 20 and 26. As a result, a thin film is simultaneously and uniformly coated on the inner and outer faces of the material 22 to be treated by a chemical vapor growth method.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is based on a chemical vapor deposition method (CVD method), which simultaneously coats both the inner and outer surfaces of a tubular workpiece such as a long pipe. The present invention also relates to a thin film coating method and apparatus that enable uniform thin film coating.

[Conventional technology and its problems]

For example, piping for heat exchangers in nuclear power plants, petroleum refining plants, etc. requires long pipes whose inner and outer surfaces are coated with corrosion-resistant films, etc., for reasons such as longer life.

However, until now, there has been no CD/D device capable of simultaneously and uniformly coating the inner and outer surfaces of such a long pipe with a corrosion-resistant film or the like.

For example, FIG. 4 shows an example of a conventional thermal CVD apparatus, in which a reaction gas G is supplied into a vacuum vessel 2, which is a reaction chamber, and a workpiece 3 is heated to a high temperature by a heater 4. Although a thin film is formed on the surface of the object 3 to be treated, if the object 3 to be treated is a long pipe, the flow of the reaction gas G may be uneven inside and outside the long pipe or in the length direction. For these reasons, it is impossible to uniformly coat both the inner and outer surfaces with a thin film at the same time.

FIG. 5 shows an example of a conventional BM conductive-coupled plasma CVD apparatus, in which a vacuum vessel 2 made of a quartz tube, etc.
A high-frequency coil 5 is wound around the coil 5, and high-frequency power is supplied from a high-frequency power supply 6 to the high-frequency coil 5 to generate plasma 7, thereby forming a thin film on the surface of the object 3. When the object 3 to be processed is a long pipe, it is difficult to generate the plasma 7 on both the inner and outer surfaces due to the non-uniformity of the flow of the reactant gas G as mentioned above and the fact that the plasma 7 is not generated well in the innermost part of the long pipe. It is not possible to simultaneously and uniformly coat a thin film on both sides.

Furthermore, FIG. 6 shows an example of a conventional parallel plate type plasma CVD apparatus, in which plasma 7 is generated by supplying high frequency power from a high frequency power source 6 to two electrodes 8 and 9 provided in the vacuum vessel 2. is generated, thereby forming a thin film on the surface of the object to be treated 3.
When the object 3 to be treated is a long pipe, it is impossible to uniformly and uniformly coat both the inner and outer surfaces thereof with a thin film for substantially the same reason as in the case of the apparatus shown in FIG.

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a thin film coating method and an apparatus therefor that can simultaneously and uniformly coat both the inner and outer surfaces of a tubular workpiece such as a long pipe.

[Summary of the invention]

One feature of the present invention is that a reactive gas is supplied to the inner and outer surfaces of a heated tubular workpiece from a plurality of regions that are separately and dispersed. Since the flow of the reaction gas in the length direction can be made uniform, the thin film can be coated simultaneously and uniformly on both the inner and outer surfaces of a tubular workpiece such as a long pipe.

Another feature of the present invention is that reactive gases are supplied to the inner and outer surfaces of the workpiece separately from a plurality of dispersed regions, and plasma is generated separately inside and outside the workpiece. According to this method, it is possible to make the flow of reactant gas and the distribution of plasma uniform inside the workpiece and in the length direction, so that it is possible to uniformly distribute the flow of the reactant gas and the plasma on both the inside and outside of the workpiece, such as a long pipe, simultaneously and uniformly. can be coated with a thin film.

〔Example〕

FIG. 1 is a schematic sectional view showing a thin film coating apparatus according to an embodiment of the present invention. This device consists of a cylindrical vacuum container 12
, an outer tube 16 of a double tube type arranged coaxially within the vacuum container 12 and having a large number of holes 20 dispersedly drilled on its inner surface; The inner tube 2 has a large number of holes 26 distributed on its outer surface.
4. The lengths of the vacuum container 12, the outer tube 16, and the inner tube 24 are equal to or longer than the length of the tubular object 22, such as a long pipe, and there is a gap between the outer tube 16 and the inner tube 24. The object to be processed 22 can be housed and fixed coaxially. Further, in this example, the cross-sectional shapes of the vacuum container 12, the outer tube 16, and the inner tube 24 are each circular, similar to that of the object to be processed 22.

One end of the outer tube 16 and the inner tube 24 are each closed in this example, and a gas supply source 30 is provided at the other end for supplying the reaction gas G from the outside into the cavity 18 of the outer tube 16 and into the inner tube 24. and 32 are connected to each other. A cylindrical heater 14 for heating the workpiece 22 is coaxially provided between the vacuum container 12 and the outer tube 16. A vacuum evacuation device 28 is connected to the end of the vacuum container 12 to evacuate the inside thereof.

In this case, the hole 20.2 in the outer tube 16 and the inner tube 24
6, it is preferable to make the flow of the reaction gas G as uniform as possible inside and outside the object 22 and in the length direction.
When supplying the reaction gas G from one end side of the outer tube 16 and the inner tube 24, for example, the number of holes 20.26 on the downstream side of the reaction gas G is made larger than those on the upstream side, or the number of holes 20.26 on the downstream side of the reaction gas G is increased.
The diameter of 26 may be made larger than that on the upstream side, or both may be used in combination.

Further, the outer tube 16 and the inner tube 24 may be supplied with the reaction gas G from a common gas supply source, but if they are provided with separate gas supply sources 3o and 32 as in this example, The same type of reaction gas G can be supplied to the inner and outer surfaces of the object 22, or different types of reaction gases G can be supplied to coat the inner and outer surfaces of the object 22 with different types of thin films.

Note that the outer tube 16 and the inner tube 24 can be water-cooled to prevent the supplied reaction gas G from being thermally decomposed and precipitated within the outer tube 16 and the inner tube 24.

Further, the heater 14 may be provided outside the vacuum container 12 (
Alternatively, a high frequency heating means (see the frequency coil 34 and high frequency power supply 36 in FIG. 2) may be used instead, or both may be used in combination.

In addition, the vacuum chamber 12 may be evacuated from a position outside this folded plate, and furthermore, if atmospheric pressure CVD is used, the vacuum chamber 12
Instead, a normal reaction vessel may be used and the evacuation device 28 may be omitted.

During processing by the above apparatus, the inside of the vacuum container 12 is evacuated as necessary, the object to be processed 22 is heated to a predetermined temperature, and the reaction gas G is supplied to the outer tube 16 and the inner tube 24.

This reaction gas G is supplied to a large number of holes 2 in the outer tube 16 and the inner tube 24.
The reactant gas G is ejected from the reactor gas G and is supplied to the inner and outer surfaces of the heated object 22 from a plurality of separately distributed regions.

Therefore, in this way, unlike the conventional case, it is possible to make the flow of the reaction gas G uniform both inside and outside the object 22 to be treated and in the length direction, so that it is possible to uniformly flow the reaction gas G on both the inside and outside of the object 22 to be treated simultaneously and uniformly. can be coated with a thin film. Therefore, for example, it is possible to obtain a long pipe with excellent corrosion resistance, whose inner and outer surfaces are coated with a uniform corrosion-resistant film. Moreover, according to the above-mentioned apparatus, a large number of holes 20.
Since the outer tube 16 and the inner tube 24 in which the tubes 26 are dispersedly opened are used, the flow of the reactant gas G can be made uniform inside and outside the object 22 to be treated and in the length direction with a simple structure.

Note that the film quality, film formation rate, etc. in the above case can be controlled to desired values by the flow rate of the reaction gas G, the heating temperature of the object to be processed 22, the degree of vacuum during film formation, etc.

Furthermore, various types of coating film, such as ceramics and metals, can be used by appropriately selecting the reaction gas G used. For example, as the reaction gas G, T
If i Cl 4 + N H 3 is used, titanium nitride (T
i N ), T i Cl t + CHa to produce titanium carbide (TiC), BzH6+NH3 to produce boron nitride (BN), 5iC14+NH:l to produce silicon nitride (SINX), and BiI3"CHa to produce boron carbide ( BC), 5iC14+CH4 can be used to coat ceramics such as silicon carbide (SiC).Of course, as mentioned above, if the types of reaction gas G supplied to the inside and outside of the workpiece 22 are different, the workpiece 22 can be coated. It is also possible to coat the inside and outside of the object 22 with another thin film.

FIG. 2 is a schematic sectional view showing a thin film coating apparatus according to another embodiment of the present invention. Mainly explaining the differences from the embodiment shown in FIG. 1, this device has the above-mentioned outer tube 16.
In order to make the inner tube 24 also serve as an electrode for high frequency radiation, both are made of a conductive material. And this outer tube 1
High frequency power sources 42 and 44 for supplying high frequency power are connected to the inner tube 6 and the inner tube 24 via matching boxes 38 and 40 for impedance matching, respectively. Furthermore, a bias power supply 46 for applying a DC negative bias voltage is connected to the object 22 to be processed.

In this case, high frequency power may be supplied to the outer tube 16 and the inner tube 24 from a common high frequency power source, but if separate high frequency power sources 42 and 44 are used as in this example, Since the high-frequency power can be arbitrarily changed between the inside and outside of the object 22, the thickness, quality, etc. of the coating film can be controlled on the inside and outside surfaces of the object 22.

Although the bias power supply 46 is not essential, if it is provided and the bias voltage applied to the object 22 is controlled, the quality of the film coated on the object 22, the film formation rate, etc. can be controlled. Can be done.

Furthermore, although the heater 14 does not necessarily need to be provided, if it is provided so that the workpiece 22 can be heated, this device can be used not only as a plasma CVD device but also as a thermal CVD device. Further, in the case of a plasma CVD apparatus, it is also possible to improve the adhesion of the coating film. However, as a means for heating the object 22, instead of providing the heater 14, the vacuum container 12 is made of a quartz tube or the like, a high frequency coil 34 is wound around the outside of the vacuum container 12, and high frequency power is supplied to this from a high frequency type tA36. The object to be processed 22 may be heated by induction.

In that case, if a slit 17 as shown in FIG. 3 is provided in the axial direction of the outer tube 16, the object to be processed 22 can be heated without the outer tube 16 being heated too much. Note that the hole 20 is not shown in FIG. 3.

In the above apparatus, (1) high-frequency power is supplied to the outer tube 16 and the inner tube 24 to generate plasma; (2) high-frequency power is supplied to the outer tube 16 and the inner tube 24 to generate plasma; Film formation can be performed in three ways: 1. heating the object 22 without supplying high frequency power to the outer tube 16 and the inner tube 24;

Since the above item (2) is the same as in the embodiment shown in FIG. 1, its explanation will be omitted here.

For example, when performing the treatments described in (1) and (2) above, the vacuum container 1
After exhausting the inside of 2 to below about lXl0-5 Torr,
The reaction gas G is supplied into the vacuum vessel 12 at a temperature of several mTorr to several tens of Torr in the same manner as in the case of FIG.
6 and the inner tube 24 with high frequency power. As a result, the reactant gas G is supplied to the inner and outer surfaces of the workpiece 22 from a plurality of regions that are separately and dispersed, and plasma is applied to the workpiece by high-frequency discharge using the outer tube 16 and the inner tube 24. generated separately inside and outside 22.

Therefore, in this way, unlike the conventional case, it is possible to make the flow of the reactant gas G and the distribution of plasma uniform inside and outside the workpiece 22 and in the length direction, so that both the inside and outside of the workpiece 22 can be uniformly distributed. can be coated with a thin film simultaneously and uniformly. Furthermore, since the reactive gas G is activated by plasma, there are advantages such as film formation being possible at a lower temperature compared to the embodiment shown in FIG. Moreover, according to the above-mentioned device, the outer tube 16 and the inner tube 24 made of a conductive material in which a large number of holes 20, 26 are dispersed and drilled for supplying the reaction gas G and generating plasma are also used. So,
The spacing configuration makes it possible to make the flow of the reactant gas G and the distribution of plasma uniform inside and outside the object 22 to be processed and in the length direction.

In the above case, the type of thin film that can be coated on the object 22 to be processed is almost the same as in the case of FIG. In addition, the film quality, film formation rate, etc. are determined by the flow rate of the reaction gas G, the heating temperature of the object 22,
It can be controlled to a desired value by adjusting the degree of vacuum during film formation, the high frequency power supplied to the outer tube 16 and the inner tube 24, the bias voltage applied to the object to be processed 22, etc.

Finally, although the case where the straight pipe-shaped object to be processed 22 is processed has been described above, the vacuum container 12, the outer tube 16, the inner tube 24, etc. are used as the object to be processed 22. Of course, if it is compatible with this, it is possible to process even a curved tube-shaped object 22. Furthermore, the cross-sectional shape of the object to be processed 22 is not necessarily limited to a circular shape.

〔Effect of the invention〕

As described above, according to the first method of the present invention, it is possible to make the flow of the reaction gas uniform inside and outside the tubular object to be treated and in the length direction. A thin film can be coated simultaneously and uniformly on both the inner and outer surfaces of the treated object.

Further, according to the second method of the present invention, plasma is used to activate the reaction gas, and the flow of the reaction gas and the distribution of the plasma can be made uniform inside and outside the tubular workpiece and in the length direction. Therefore, the thin film can be simultaneously and uniformly coated on both the inner and outer surfaces of a tubular object such as a long vibrator at a lower temperature than in the first method.

Further, according to the first apparatus of the present invention, since the outer tube and the inner tube having a large number of dispersed holes are used for supplying the reaction gas, the structure is simple and the inner and outer tubes of the tubular object to be treated can be controlled. The flow of the reactant gas in the length direction can be made uniform.

Furthermore, according to the second device of the present invention, a large number of holes are dispersedly drilled for supplying reaction gas and generating plasma.
Since the outer tube and inner tube are both made of electrically conductive material,
With a simple configuration, the flow of reactant gas and the distribution of plasma can be made uniform inside and outside the tubular object to be processed and in the length direction.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing a thin film coating apparatus according to an embodiment of the present invention. FIG. 2 is a schematic sectional view showing a thin film coating apparatus according to another embodiment of the present invention. FIG. 3 is a schematic perspective view showing another example of the outer tube. FIG. 4 is a schematic diagram showing an example of a conventional thermal CVD apparatus. FIG. 5 is a schematic diagram showing an example of a conventional inductively coupled plasma CVD apparatus. Figure 6 shows a conventional parallel plate type plasma CV
It is a schematic diagram showing an example of D device. DESCRIPTION OF SYMBOLS 12... Vacuum container, 14... Heater, 16... Outer tube, 20.26... Hole, 22... Processing object, 24...
...Inner tube, 28...Vacuum exhaust device, 30.32...
Gas supply source, 42.44...High frequency power supply, G...Reactive gas.

Claims (4)

[Claims] (1) A method in which a thin film is coated on both the inner and outer surfaces of a tubular workpiece by chemical vapor deposition, and reactions occur from multiple regions separately and dispersed on the inner and outer surfaces of the heated workpiece. A thin film coating method characterized by supplying a gas. (2) A method in which a thin film is coated on both the inner and outer surfaces of a tubular workpiece by chemical vapor deposition, and a reactive gas is supplied to the inner and outer surfaces of the workpiece separately from multiple dispersed regions. A thin film coating method characterized in that the plasma is generated separately on the inside and outside of the object to be treated. (3) A device that coats a thin film on both the inner and outer surfaces of a tubular workpiece by chemical vapor deposition, which includes a cylindrical container and a double tube type placed inside the container. It has an outer tube in which a large number of holes are drilled in a distributed manner, and an inner tube that is placed inside the outer tube and has a large number of holes in a distributed manner on its outer surface. What is claimed is: 1. A thin film coating apparatus, which is capable of coaxially storing objects to be processed, and further comprising means for supplying a reaction gas to the outer tube and the inner tube, and means for heating the objects to be processed. (4) An apparatus for coating both the inner and outer surfaces of a tubular workpiece with a thin film using a chemical vapor deposition method, which includes a cylindrical vacuum container;
It is a double-tube type made of conductive material placed inside a vacuum container, and consists of an outer tube with many holes distributed on its inner surface, and a conductive material placed inside the outer tube. It has an inner tube with many holes distributed on its outer surface.
A tubular object to be processed can be coaxially stored between the outer tube and the inner tube, and further includes a means for evacuating the vacuum container, a means for supplying a reaction gas to the outer tube and the inner tube, and a means for evacuating the vacuum container. A thin film coating device comprising: means for supplying high frequency power to a pipe and an inner pipe.