JPS6358226B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical field The present invention relates to a plasma CVD apparatus that can be industrially mass-produced. The CVD method is a method of coating a substrate with a specific compound by causing a reaction through thermal activation, and plasma CVD is one of these methods.

(b) Background of the technology Chemical vapor deposition (CVD) is currently used in the semiconductor industry,
This technology is widely used in optical fibers and cutting tools. Since this CVD method requires a relatively high temperature, various methods have been attempted to lower the processing temperature as much as possible. One is to use organic compounds as a source and take advantage of their decomposition at low temperatures. Another method uses plasma discharge to accelerate the reaction. The latter is already used in the production of amorphous Si and Si ₃ N ₄ passivation films, and Figure 1 shows one of the devices.
Give an example. A vacuum container 6 has a stage for placing the workpiece 1 with a built-in heater 2, and the inside of the container is maintained at a constant reduced pressure by exhausting air through an exhaust hole 5 by a vacuum pump, and the heater maintains a constant temperature. The reactant gas introduced from the gas introduction hole 4 in a heated state is connected to the power supply 7 between the electrode 8 and the workpiece mounting table.
The plasma passes through the discharged plasma and is ionized to coat the surface of the object 1 to be processed.

Conventionally, this equipment has been designed to coat only one side of a flat substrate, and the manufacturing equipment is designed to accommodate this, aiming for processing at temperatures below 500°C. JP-A-58-164777 describes a method of forming a flat substrate in multiple stages, but a large temperature distribution occurs on the electrode surface, making uniform coating difficult.
Furthermore, Japanese Patent Application Laid-open No. 56-5972 proposes a method for mass-producing film formation by plasma discharge, in which a support is installed in a possible state and a wire electrode is used, but the plasma generation conditions are limited. , there is also a problem with plasma uniformity.

On the other hand, in the case of coated cemented carbide for cutting tools, for which the CVD method is often used, it is necessary to coat all surfaces three-dimensionally, and therefore it is impossible to use the conventional equipment described above for mass production. . Further, even when coating a flat surface, there are problems such as temperature distribution and maximum temperature, and improvements to the above-mentioned conventional apparatus are desired.

(C) Disclosure of the Invention The inventors have arrived at the present invention as a result of studying a mass production device that can maximize the characteristics of the plasma CVD method. We have developed a device that can uniformly cover targets.

FIG. 2 shows a cross-sectional view showing an outline of the vapor deposition apparatus of the present invention. The requirements of the present invention are to arrange cylindrical electrodes 9, 9' and 10, 10' having the same central axis and different diameters in the vacuum container 6, to generate plasma between them, and to generate a plasma therein. The object 1 is fixedly installed on a substrate support (not shown), and heating is performed by a heater 2 provided outside the container, thereby making it possible to make the temperature distribution uniform. The generation of plasma can be controlled completely separately. Furthermore, it has become possible to raise the processing temperature to 1000°C or more. The substrate support for fixing the object to be processed is a heat-resistant material such as a stainless steel (SUS316) rod or pipe that is attached to the wall of the vacuum chamber (separate wall from the external heater) through an insulating material such as alumina. It is fixed and supported parallel to the electrode axis between the inner and outer electrodes.

The reason why the electrodes 9 and 10 are cylindrical is to ensure that discharge occurs uniformly. Further, since it is generally preferable for an externally heated vacuum container to have a cylindrical shape in terms of strength, the container itself may serve as an electrode if the maximum volume is to be utilized as a reaction container.

The central axes of the internal electrode 9 and the external electrode 10 should preferably coincide, and this is important for making the plasma generation state uniform.

The object to be processed is placed between the inner and outer electrodes, but both electrodes may be insulated or may be attached to one electrode. Furthermore, applying some kind of bias to the object to be processed itself is a known method, and the effects of the present invention are unchanged.

Plasma can be generated using either a direct current electric field or a high frequency electric field, but in the case of a series connection, the polarity of the object to be treated must be carefully considered depending on the purpose.

(D) Embodiment of the best mode for carrying out the invention 1 Inside a vacuum container made of SUS316 and measuring 120φ x 500mmH, an outer electrode of 100φmm made of SUS316 plate material is installed.
The internal electrodes of 50φmm were installed with the same central axis.
A resistance heating furnace using a nichrome wire as a heater was installed outside the container. Next, a plurality of stainless steel rods of 6 mmφ x 300 mm were provided as substrate supports between the inner and outer electrodes in parallel to the center of the electrodes. The support was fixed to the side wall of the vacuum vessel via an alumina insulator. A SUS304 plate of 100 x 15 x 1 mm was bolted to this substrate support, and 2.5 μm of Al ₂ O ₃ was vapor-deposited using this as a substrate. Evaporation of AlCl ₃ 3 after evacuating the vacuum vessel
%, CO ₂ 6%, H ₂ 91% gas was introduced at a flow rate of 700 c.c./min. between the inner and outer electrodes at a pressure of 1 Torr.
A discharge of DC750V and 2A was generated, and the treatment was carried out at 500°C for 2 hours.

When the cross section of the obtained film was observed under an optical microscope, a uniform film with a thickness of 2.3 to 2.7 μm was observed over the entire surface of the substrate.

Example 2 Inside a vacuum vessel made of SUS316 and having dimensions of 350φ×700mmH, an external electrode of 300φmm and an internal electrode of 120φmm made of SUS316 plate material were installed on the same central axis.
A resistance heating furnace using Kanthal wire as a heater was installed on the outside of the container.Next, support holes were provided at equal intervals between the inner and outer electrodes, parallel to the center axis of the electrodes.
A plurality of mm stainless steel rods were provided as substrate supports. The support was fixed to the side wall of the vacuum vessel via an alumina insulator. An ISO P30 cemented carbide chip (shape and dimensions are
SNGA) was fixed and supported by passing bolts through a hole made in the same cemented carbide chip (this is for fixing the holder during use) and a hole in the support. Vapor deposition is TiCl ₄ 2
%, CH ₄ 18%, and H ₂ 80% gas was introduced at a rate of 3/min, and a discharge was generated between the inner and outer electrodes using high frequency power (500 W) of 13.56 MHz. pressure
By processing for 1 hour at 2Torr and temperature of 750℃
A TiC film with a thickness of 3μ was obtained. 1800 of the above-mentioned cemented carbide chips were installed in this container, but the variation was 3 μm.
Extremely uniform coating was achieved with ±0.3μ. Using this as a substrate, 2.5μ of Al ₂ O ₃ was deposited. Vapor deposition is
After evacuating the vacuum vessel _AlCl3 3%, CO2 ₆ %, _H2 91
% gas was introduced at a flow rate of 700c.c./min., and the pressure
A discharge of DC750V and 2A was generated between the inner and outer electrodes at 1 Torr, and the treatment was carried out at 500°C for 2 hours.

When the cross section of the obtained film was observed under an optical microscope, a uniform film with a thickness of 2.3 to 2.7 μm was observed over the entire surface of the substrate.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an outline of a conventional vapor deposition apparatus, and FIG. 2 is a sectional view showing an example of the apparatus of the present invention. 1: Base material, 2, 2': Heater, 3: Heating power source, 4: Gas introduction hole, 5: Vacuum exhaust hole, 6: Vacuum container, 7: Discharge power source, 8: Electrode, 9, 9': Inside Electrode, 10, 10': external electrode.

Claims (1)

[Claims] 1. Different diameters with the same center in the vacuum container 2.
It has two cylindrical electrodes, a power supply connected to these electrodes generates plasma between the inner and outer electrodes using direct current or alternating current, and there is a support device that places the object to be processed between the inner and outer electrodes. One part of the container has a reaction gas introduction hole and the other end has a vacuum exhaust hole,
A vapor deposition apparatus comprising a heating device that introduces a reactive gas into a plasma generating section and heats the object to be processed and the reactive gas from outside a vacuum container.