JP4041878B2 - Microplasma CVD equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, an inorganic material typified by a carbon-based material such as graphite and glassy carbon is applied to the surface of various substrate materials such as glass, metal, ceramics, and polymer at a micrometer order on an unheated substrate under atmospheric pressure. The present invention relates to a high-density microplasma CVD apparatus that can be directly deposited in a region without using a mask or the like.
[0002]
[Prior art]
In order to deposit various inorganic materials typified by carbon materials such as graphite and glassy carbon on the substrate, these materials have extremely high melting points, and because of the induction of their crystal structures, Preparation using a heated substrate or a high temperature field is used. For example, carbon nanotubes and the like that have been actively studied in recent years are prepared on a substrate heated to 500 ° C. or higher by the CVD method and at a high temperature field of about 1000 ° C. by the laser ablation method. Not only on a substrate having heat resistance such as glass, ceramic and metal, but also on a substrate made of a very heat-sensitive material such as a polymer and an organic molecular film, or on a substrate on which these materials are integrated in advance. In order to deposit such inorganic materials and to combine them with inorganic materials without destroying these organic materials, the deposition of inorganic materials does not require a substrate heated to a high temperature or a high temperature field. Technology is required.
[0003]
In a plasma process typified by sputtering, which is often used in processing of semiconductors and the like, deposition of inorganic materials is usually performed in a vacuum of about several mTorr to several tens of mTorr in order to generate a stable plasma. Has been made. However, when depositing an inorganic material on a substrate using a plasma process on a substrate such as a polymer and an organic molecular film or on a substrate on which these materials have been previously integrated, the gas from these substrate materials It is not always preferable to use the plasma process because impurities are mixed into the deposit or defects are generated due to generation or evaporation of volatile components contained in the substrate itself.
[0004]
On the other hand, in electronic devices such as semiconductors, miniaturization is progressing, and miniaturization using lithography has been achieved. If a material can be directly deposited in a micrometer-scale space, a lithography process can be omitted in manufacturing an electronic device such as a semiconductor. Therefore, a technique capable of directly depositing an inorganic material in a micrometer-scale space is also required.
[0005]
[Problems to be solved by the invention]
An object of the present invention, the inorganic material typified by a surface of various substrate materials in the carbon-based material such as graphite and glassy carbon by a simple process, under reduced pressure or under pressure, without particularly pressurized heat substrate It is to directly deposit without using a mask or the like in a micrometer order region.
[0006]
[Means for Solving the Problems]
The present invention is configured cylindrical insulating material made plasma torch, a plasma gas supply system, the plasma generating high frequency power source, a matching box, a plasma lighting igniter, from the three-axis manipulator for controlling the position of the atmospheric gas spraying nozzles and the deposition substrate The above-described problems are solved by a high-density microplasma CVD apparatus.
[0007]
For example, in order to deposit a carbon nanotube-based material on a substrate, a hydrocarbon gas such as methane may be mixed with a plasma gas typified by an inert gas such as argon and supplied to the plasma nozzle. Alternatively, it is possible to spray a gas containing hydrocarbon gas onto the non-heated substrate simultaneously with the high-density plasma. Such inorganic materials can be prepared not only under atmospheric pressure but also under reduced pressure to high pressure.
[0008]
Embodiment
FIGS. 1 and 2 show an outline of two different microplasma CVD apparatuses, and FIG. 3 shows two different shapes of plasma torches. The difference between the apparatus in FIG. 1 and FIG. 2 is due to the difference in the plasma lighting system. These arise from differences in the plasma ignition coil and the grounding point (ground). In the case of FIG. 1, a high voltage of 15 kV is applied from the igniter to the plasma lighting coil for several seconds as shown in FIG. 3 to induce a discharge between the plasma lighting coil and the wire in the plasma torch. This is a type in which plasma is lit using (plasma lighting method 1).
[0009]
In contrast, in the case of FIG. 2, the high voltage of the igniter is applied to the plasma torch connection port, and the high voltage is also applied to the wire via the capillary support pipe. As a result, a discharge is induced between the wire and the high frequency coil, and thereby plasma is lit (plasma lighting method 2). In this case, the plasma lighting coil shown in FIG. 3 is unnecessary. The difference in the plasma lighting method can be selected according to the plasma gas used, the type of atmospheric gas, the pressure, and the like. Furthermore, depending on the high-frequency output, the wire, the plasma lighting coil, and the igniter can be omitted.
[0010]
In addition, the high frequency that can be used in this plasma apparatus is 10 kHz to 1 GHz, and the power can be a high frequency of about 0.1 W to 100 W. In addition, high-frequency matching is very important in order to efficiently supply high-frequency power to the plasma torch, so that the reflected wave that returns from the coil to the high-frequency power source immediately after the plasma is turned on is preferably completely eliminated by the matching box. Or it is necessary to prepare it to be the minimum.
[0011]
FIG. 3 shows a usable plasma torch shape. The plasma torch is used by being inserted into the plasma torch connection port of the CVD apparatus. The plasma torch includes a capillary support pipe, a capillary, and a wire. As described above, the wire and the plasma lighting coil can be omitted when the inner diameter of the capillary is 500 μm or more, but requires high high-frequency power. It is desirable to use a high melting point metal such as tungsten or tantalum for the wire. The material of the capillary support pipe is preferably a conductive material such as stainless steel. However, when plasma lighting by an igniter is not required, the material may not be conductive and may be a material such as polymer or ceramic. The capillary material needs to be an insulating material, and quartz glass, ceramics, polymer, or the like can be used.
[0012]
As shown in FIG. 3, it is possible to use a cylindrical shape or a shape in which the tip portion is narrowed as shown in FIG. 3, and the inner diameter of the high frequency coil portion of the capillary is preferably 500 nm to 2000 μm.
[0013]
The substrate support is connected to a triaxial manipulator, and the distance between the plasma torch tip can be changed, and the distance between the substrate and the plasma torch tip can be adjusted between 0 mm and 100 mm. It is. When depositing material in a submicrometer area on the substrate, it is desirable that the distance between the substrate and the tip of the plasma torch is 5 mm or less, and the size of the deposited material can be controlled by changing this distance. it can. It is also possible to deposit the material linearly by moving the substrate left and right. Therefore, by moving the substrate back and forth, right and left, a pattern can be drawn in a micrometer region without using a mask or the like.
[0014]
【Example】
Next, the process of depositing a carbon-based material will be specifically described below. First, the reaction vessel is first depressurized to a pressure of 50 mTorr or less with a vacuum pump, and atmosphere gas, for example, a mixed gas of hydrocarbons such as air, argon, and methane, and argon and the like is filled from the gas introduction pipe so as to have a predetermined pressure. . Argon or a mixed gas of argon and hydrocarbon is supplied through the plasma gas introduction pipe. At this time, the total gas supply amount can be changed from 0.5 ccm to 200 ccm, and the concentration of the hydrocarbon gas can be changed from 1% to 5%. Usually, if the concentration of hydrocarbon gas is increased to 5% or more, the stability of the plasma is lowered, and the plasma may not light.
[0015]
When the plasma gas flow rate is stabilized, a high frequency of about 450 MHz is applied to the high frequency coil with an output of 35 W. Thus, high-frequency electromagnetic field is generated in the coil Maki turning portion of the capillary, the distal end portion of the wire over 22 reachable in the coil therewith is subjected to high frequency induction heating, the heating condition. In this state, when the igniter 8 is operated and a high voltage of, for example, about 15 kV is applied to the ignition coil 6, a discharge is generated at the tip of the capillary, and the plasma generated by this discharge is used as a seed flame to generate a high frequency. Inductive plasma is generated by the high frequency power supplied through the coil 7. Induction plasma generated is supplied with thermal electrons generated from the wire over 22 high temperature state is maintained stably. As a result, a plasma flame having a very small diameter is ejected from the tip of the capillary tube. Thereafter, after matching the high frequency, a carbon-based material is deposited on the substrate. In some cases, it is also possible to perform deposition by turning on plasma only with argon gas and blowing methane gas onto the substrate through a pipe.
[0016]
Using the above apparatus, a quartz glass capillary having a tip diameter of about 100 μm as a plasma torch, a pressure of 760 mTorr in air, a 1% methane-argon mixed gas as a plasma gas, Hastelloy and a silicon wafer as a substrate, The distance from the tip of the plasma torch was 2 mm. Carbon-based materials were deposited on the substrate for 2 minutes each at three different flow rates of plasma gas supply of 50, 100, and 200 ccm. FIG. 4 shows scanning electron micrographs of the deposits produced at plasma gas supply rates of 50 ccm and 100 ccm. When the supply amount was 50 ccm, spherical substances were deposited on the substrate (FIG. 4A). On the other hand, when produced at 100 ccm, a spherical substance could not be observed (FIG. 4-2). Even when prepared at 200 ccm, spherical substances were deposited. In any case, the deposit is deposited in a circular shape having a diameter of 200 μm, and its size does not depend so much on the supply amount of the plasma gas.
[0017]
The microstructure of the three kinds of carbonaceous material deposits obtained was examined by transmission electron microscope. FIGS. 5, 6 and 7 show transmission electron micrographs and electron diffraction patterns of the deposits produced at plasma gas supply rates of 50 ccm, 100 ccm and 200 ccm, respectively (however, only transmission electron micrographs are shown in FIG. 6). The deposit produced with a plasma gas supply rate of 50 ccm is spherical and has a carbon polyhedron because the electron diffraction pattern matches that of graphite.
[0018]
On the other hand, a layered structure of graphite was observed in the deposit produced with a plasma gas supply rate of 100 ccm, and the deposit was kraft. Moreover, although the deposit produced with the plasma gas supply amount of 200 ccm was spherical, the electron diffraction pattern was a hello pattern, so the deposit was amorphous carbon.
[0019]
【The invention's effect】
As described above, the carbon-based material can be prepared under atmospheric pressure without any special substrate heating in a region of about 200 μm by the high-density microplasma CVD apparatus. Here, it has also been clarified that the structure of the carbon-based material can be controlled by controlling the flow rate of the plasma gas containing the hydrocarbon gas.
[Brief description of the drawings]
1 is a diagram of a high-density micro-plasma CVD apparatus using plasma lighting method 1. FIG. 2 is a diagram of a high-density micro-plasma CVD apparatus using plasma lighting method 2. FIG. 3 is a plasma torch used in a high-density micro-plasma CVD apparatus. Fig. 4 Scanning electron micrograph of carbon-based material deposit prepared by high-density micro-plasma CVD apparatus. Fig. 5 Carbon-based material deposit prepared by high-density micro-plasma CVD apparatus with a plasma gas supply rate of 50 ccm. Transmission electron micrograph and electron diffraction pattern [Fig. 6] Transmission electron micrograph of a carbon-based material deposit produced with a high-density micro-plasma CVD apparatus at a plasma gas supply rate of 100 ccm [Fig. 7] With a high-density micro-plasma CVD apparatus Transmission electron micrographs and electron diffraction of carbon-based material deposits prepared with a plasma gas supply rate of 200ccm Turn [Description of the code]
DESCRIPTION OF SYMBOLS 1 Plasma gas introduction pipe 2 Pipe 3 Insulation flange 4 Plasma torch connection port 5 Plasma torch 6 Plasma ignition coil 7 High frequency coil 8 Igniter 9 High frequency power supply 10 High frequency matching box 11 Substrate 12 Substrate support base 13 Axis 14 Triaxial manipulator 15 Reaction vessel 16 Plasma gas introduction valve 17 Gas introduction valve 18 Gas introduction pipe 19 Pressure adjustment valve 20 Vacuum pump 21 Capillary support pipe 22 Wire 23 Capillary

Claims (7)

A microplasma CVD apparatus comprising: a substrate support with a substrate attached at the tip; a plasma insulating torch made of a cylindrical insulating material; a plasma gas supply system; and a high frequency coil for exciting the plasma gas A plasma generating high frequency power source for supplying high frequency power to the coil, and a control device for controlling the position of the substrate. The plasma torch includes a wire in the vicinity of the plasma generating region in the torch, and the plasma torch micro plasma CVD apparatus, wherein the inner diameter of the high-frequency coil portion of the capillary constituting is less than 500nm or 500 mu m.   The microplasma CVD apparatus according to claim 1, wherein the wire is a refractory metal.   The microplasma CVD apparatus according to claim 1 or 2, wherein the plasma gas supply system is configured to supply the plasma gas and a deposition gas for depositing on the substrate.   3. The microplasma CVD apparatus according to claim 1, wherein the microplasma CVD apparatus includes a deposition gas supply system for supplying a deposition gas for deposition on a substrate in addition to the plasma gas supply system. CVD equipment.   A high voltage is applied between an ignition coil provided on the outer periphery of the plasma torch and the wire provided in the torch, and the plasma gas is discharged. Item 5. The microplasma CVD apparatus according to any one of items 1 to 4. Plasma torch connection port, the capillary support pipe and the wire electrically connected, by applying a high voltage between the wire and the high frequency coil, billed you and performs ionization of the plasma gas Item 5. The microplasma CVD apparatus according to any one of items 1 to 4 .   The microplasma CVD apparatus according to any one of claims 1 to 6, wherein the plasma gas is argon, and the deposition gas is hydrocarbon.

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