JPH02184595A - Production of diamond thin film and apparatus therefor - Google Patents

Abstract

PURPOSE:To obtain the title thin film with large area by ionizing, in a specified mode, following introduction of a raw material gas into a vacuum to separate out a diamond thin film on a substrate. CONSTITUTION:A hydrocarbon raw material gas or a raw material gas capable of forming hydrocarbons through reaction such as decomposition is introduced into a vacuum. A plurality of cathode hot filament are arranged in a zigzag or linear row (or rows) at specified intervals extending in a specified direction, and while said gas is passed among these filaments, a specified electric current is energized in said filaments to effect their heating, thus separating out a diamond thin film on a substrate. With the above-mentioned arrangement, a anticathode can be provided so as to surround at a nearly equal distance from each of these filaments, resulting in uniform-acting voltage applied between the hot filaments as cathode and the anticathode, leading to uniform ionization of the hydrocarbon gas due to thermoelectrons, thus obtaining the objective diamond thin film of large area with excellent characteristics.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a method and apparatus for producing a diamond-like thin film, and more particularly, to a method and apparatus for producing a diamond-like thin film having a large area. The diamond-like thin film also has the characteristics of being a diamond-like film with good surface smoothness and excellent crystallinity.

(Prior art) Many methods have been proposed for producing diamond or diamond-like carbon thin films using the vapor phase method, but a film with a sufficiently large area has not been obtained. Plasma methods including high frequency and microwave;
There are ionization vapor deposition methods that utilize gas ionization, and CVD methods that utilize gas phase reactions. However, in most of these methods, a high-quality film cannot be obtained unless the substrate is heated to a high temperature of 700°C or higher. 10oO℃, 700~1 for RF plasma method
000°C, and microwave plasma method requires a high substrate temperature of 700°C or higher (for example, "Surface Chemistry" Vol. 5 No. 108 (1984) No. 108-115)
page).

(Problems with the Prior Art) However, such a high substrate temperature poses a serious obstacle when attempting to increase the substrate area. This is because the larger the substrate area, the more power supplied to the film forming equipment will be applied to the substrate.
This is because it will be consumed for heating to 00°C or higher. Therefore, it would be better to use sputtering, ion beam evaporation, DC plasma, ionization evaporation, and other methods that can form a desired film even at low substrate temperatures such as 400°C or lower. No suitable means have been proposed so far to be applied to the production of.

The present invention relates to improvements in ionized vapor deposition among these methods. This method is a hydrocarbon raw material gas or a raw material gas that can produce hydrocarbons by decomposition or reaction (here, hydrocarbons are saturated hydrocarbons such as methane, ethane, propane, unsaturated hydrocarbons such as ethylene, propylene, acetylene, etc.). The raw material gases that can be decomposed to produce hydrocarbons include alcohols such as methyl alcohol and ethyl alcohol, and ketones such as acetone and methyl ethyl ketone. Examples include carbon monoxide, a mixed gas of carbon dioxide and hydrogen, etc. The raw materials include rare gases such as helium, neon, and argon, and at least one of hydrogen, oxygen, nitrogen, water, carbon oxide, carbon dioxide, etc. ) is ionized into an ion flow by means such as arc discharge between a pair of cathodes or ionization by thermionic emission between a cathode hot filament and a pair of cathodes, and this flow is accelerated by an electric field to cause it to flow onto the substrate. The ionization vapor deposition method is a method of forming a diamond-like thin film by directing the film to a diamond-like thin film. It is an excellent method because it is efficient, the diamond-like film formed has good surface properties, high hardness, high thermal conductivity, and high refractive index, and no finishing surface treatment is required. However, filaments can generally only be configured linearly, and solid filaments do not exist.

As an alternative filament, the present inventor proposed a method in which a plurality of electric heating filaments bent into a linear or U-shape with almost dotted tips are arranged uniformly in a two-dimensional coordinate system, and the entire filament is surrounded by an anticathode. Although this method was attempted (to be explained later with reference to FIG. 9), it was not possible to obtain a diamond-like thin film of good quality over a wide area, probably because the distance between the filament and the anticathode was not constant.

OBJECTS OF THE INVENTION It is an object of the present invention to improve the ionization vapor deposition method to produce diamond-like thin films with large areas.

(Summary of the Invention) The above-mentioned object of the present invention is to introduce a hydrocarbon raw material gas or a raw material gas capable of producing hydrocarbons through decomposition or reaction into a vacuum, ionize it, and deposit it on a substrate to form a diamond-like thin film. In this method, a plurality of cathode thermal filaments are arranged in a zigzag or linear row (or multiple parallel rows) in a certain direction at predetermined intervals in order to achieve the ionization, and the plurality of cathode heat filaments are The objects of the invention are achieved by a method for producing diamond-like thin films, characterized in that a heating current is applied, and an apparatus for carrying out such a method. Because a plurality of cathode hot filaments are arranged in one row in this way, it is possible to provide an anticathode surrounding these filaments at a substantially constant distance (when the filaments are composed of multiple parallel rows, each (Anticathodes surrounding each row are provided), so that the voltage applied between the cathode hot filament and the anticathode acts approximately in the same way on the cathode hot filament and the hydrocarbon gas is released by thermionic electrons. The ionization becomes -like, and a diamond-like thin film with good properties and a wide area can be produced.

More preferably, when the hydrocarbon raw material gas or the raw material gas capable of producing hydrocarbons through decomposition or reaction is introduced through a plurality of nozzles provided close to each of the plurality of cathode hot filaments, a more similar ionization effect can be obtained. .

According to the present invention, the substrate is moved in the direction of the cathode hot filament row (
In other words, if the diamond-like thin film is fed in a direction substantially perpendicular to the above-mentioned fixed direction, a continuous diamond-like thin film can be produced. Alternatively, a diamond-like thin film can be formed on a wide substrate by fixing the substrate and deflecting and scanning a plasma-like ion beam of ionized hydrocarbons in a direction approximately perpendicular to the direction of the rows of hot cathode filaments. Membrane implementation is possible. Such a deflection magnetic field can be created by using a permanent magnet or an electromagnet that generates a magnetic field in a direction perpendicular to the acceleration direction of the ion stream.

In addition, according to the present invention, the characteristics such as the excellent surface properties of the diamond-like thin film produced by the ionization vapor deposition method can be utilized as is.

The diamond-like thin film of the present invention can be used for magnetic disks, VTRs, etc.
It can be widely applied as a coating for cylinders, plastic molds, etc., and for applications that require high strength over a wide area.

(Detailed Description of the Invention) The ionization vapor deposition method, which is the basic technology of the present invention, is disclosed in Japanese Patent Application No. 63
-59377 and No. 63-59376, etc., and the embodiments of the present invention use methods and devices based on the devices described in these documents.

FIG. 1 shows a preferred first embodiment of the film forming apparatus of the present invention. In FIG. 1, 10 is a vacuum container, and 11 is a chamber, which is connected to an exhaust system 18 and drawn to a high vacuum of about 10-6 Torr. . Reference numeral 12 denotes an electrode provided on the back surface of the substrate S which is wound into a roll and sent in a fixed direction by a suitable driving means, and in this case is applied with a voltage Va. 13 is used for accelerating ions with a grid. Reference numeral 14 denotes a hot cathode filament, which is heated by an AC power source If to generate thermoelectrons, and is maintained at a negative potential.

15 is a supply port for hydrocarbon gas, which is a raw material. Also,
A counter electrode 16 is arranged surrounding the filament 14 and applies a voltage Vd between it and the filament. filament 1
4. An electromagnetic coil 19 that surrounds the counter electrode 16 and the supply port 15 and generates a magnetic field for confining the ionized gas.
is located. Therefore, Vd.

The film quality can be changed by adjusting Va and the coil current.

In Fig. 1, the hydrocarbon gas raw material introduction passage 1
A plasma excitation chamber 16 is provided at 7, thereby increasing the efficiency of the ionization device. For example, microwaves, radio frequency (RF waves), radiation, ultraviolet rays, etc. can be used for plasma excitation.

Further, in FIG. 1, a magnet 20 as shown in FIG. 2 may be placed above the filament 14 and used for deflecting the plasma-like ion beam.

However, in this case, the magnetic field strength of the magnet 20 is kept constant, and the magnetic field of the magnet is set in a direction that intersects with the traveling direction of the ion flow. In this way, a deflection angle θ is obtained for desired ions such as CHs, CH, and ions.On the other hand, ions whose mass is significantly different from these ions, such as hydrogen ions, are bent even more, and neutral particles and heavy High-quality multimer ions travel straight. Therefore, if a mask is placed in the straight direction, only highly crystalline ions will adhere to the substrate S.

11 dishes for 1 year old Next, an example of the ionization device of the present invention will be explained with reference to FIG.

FIG. 3 is a plan view of the ionization device section seen from A-A in FIG. 1. As shown in FIG. The plane of is oriented perpendicular to the column direction. Anticathodes 16 are arranged on both sides of this filament row. Furthermore, a hydrocarbon gas supply port 15 is opened at the bottom of the central portion of each filament 14 .

As shown in the example below, if the distance to the substrate is appropriately determined, the width W and spacing d of the filament, and the spacing g between the filament and anticathode are appropriately determined, the surface of the substrate Diamond-like yJWA that grows by precipitation
It was found that the film thickness and crystallinity of the film were almost constant in the direction of the filament rows.

Figure 4 shows another example of the ionization device, in this example the third
In the illustrated example, the U-shaped filaments 14 alternate in a zigzag shape offset by a fixed distance toward a pair of anticathodes 16. In this example as well, it was found that the thickness and characteristics of the diamond-like film formed were almost constant in the overall alignment direction of the filaments.

FIG. 5 is a plan view of a portion of the ionization device according to a modification of FIG. 3. The surfaces of the plurality of U-shaped hot cathode filaments 14 are parallel to the direction of the filament rows.

FIG. 6 is a modification of FIG. 4, and like FIG. 4, the surface of the U-shaped filament 14 is parallel to the surface of the anticathode.

In these examples, when the filaments 15 were arranged as shown in FIG. 9 and the anticathode 16 was placed outside the entire filament, the film thickness was not uniform and the film quality was degraded. Therefore, it is confirmed that keeping the distance between the hot cathode filament and the anticathode substantially constant is an extremely important factor.

FIG. 7 shows another example of an ionization device, in which three (generally a plurality of) devices of FIG. 3 are arranged side by side. Anticathodes of 16° and 16° are interposed between the filament rows, so that the distance between the hot cathode filament and the counter electrode is almost constant.

FIG. 8 shows yet another example of an ionization device, in which three (generally a plurality of) devices of FIG. 5 are arranged side by side. Anticathodes 16° and 16° are interposed between the filament rows, so that the distance between the hot cathode filament and the counter electrode is almost constant.

The film forming method will be explained in detail using the apparatus shown in FIG. First, the inside of the chamber 11 is made into a high vacuum to 10-' Torr, and the valve of the gas supply passage 17 is operated to supply a predetermined flow rate of methane gas, a mixed gas of methane gas and hydrogen, or a carrier such as Ar%He, Ne, etc. While introducing gas etc. from each supply port 15, the exhaust system 18 is adjusted to a predetermined gas pressure, for example, 10-ITorr. On the other hand, an alternating current If is passed through the plurality of hot cathode filaments 14 to heat them, and a potential difference Vd is applied between the filaments 14 and the anticathode 16 to form a discharge. Methane gas supplied from the supply port 15 is thermally decomposed and collides with thermoelectrons from the filament to generate positive ions and electrons. This electron collides with another pyrolysis particle. By repeating this phenomenon under the confinement effect of the magnetic field of the electromagnetic coil, methane gas becomes positive ions of thermally decomposed substances.

The positive ions are attracted by the negative potential Va applied to the electrode 12 and the grid 16, are accelerated toward the slowly moving substrate S, and collide with the substrate to perform a film-forming reaction and form a diamond-like thin film. Form. If desired, even better quality thin films can be obtained using the fixed magnets described above.

For conditions such as potential, current, temperature, etc. of each part, please refer to the previously cited patent applications and patent gazettes.

FIG. 2 shows an apparatus for manufacturing a diamond-like thin film according to a second embodiment of the present invention. In this apparatus, a substrate S is arranged at an angle with respect to the axis of the filament, and its back surface is supported by an electrode 12. . As with the first embodiment, the example shown in Figures 3.4.5.6.7 or 8 can be used as the ionization device. In this example, a variable magnet 20 for scanning the ion beam is also installed in the filament alignment direction. It is designed to generate a magnetic field of The strength of the magnetic field is gradually increased at a constant rate during the film forming operation to increase the deflection angle θ of the plasma-like ion beam at a constant rate (or vice versa).

The film forming operation in this example is basically the same as that in FIG. 1. However, this example differs in that the substrate S is fixed and the plasma ion beam is scanned by the variable magnet 20.

In the two embodiments described above, the structural features are those of the ionization device of FIG. 3.4.5.6.7 or 8. In particular, (1) multiple filaments are used, (2) the spacing of the filaments is approximately constant, (
3) It is extremely important to achieve the intended purpose that the spacing between the filament and the anticathode is approximately constant.

Examples are given below.

Film formation was performed using the ionization apparatus shown in FIG. 3 and the film formation apparatus shown in FIG. After the inside of the vacuum vessel 10 was evacuated to 10'' Torr, methane gas was introduced and the gas pressure was set at 10'' Torr to cause discharge to occur in the hot cathode filament. The magnetic flux density of the electromagnetic coil 19 was 400 Gauss, the substrate voltage was -300V, and the substrate temperature was 200°C.

Further, a current of 25 A was applied to the filament 14.

The filament is d = 2 mm and w = 10 m in Figure 3.
m, g = 8 mm. The substrate S uses aluminum foil with a thickness of 20 microns, and the feed rate is 40 mm/h.
It was set as r.

A diamond-like film with a thickness of 0.8 μm was obtained under the conditions of If = 175 A, Va = 30 V, and Vd = -30 V. The Vickers hardness was 6500 Kg/mm''.

When a film was formed on a 150 μm polyimide film under the same conditions as Example 1, the film thickness was 0.6 μm and the hardness was 5500 kg.
/mm'', it can be seen that it is possible to form a film on the surface of a plastic film.

Film formation was carried out by the method of Example 1, except that an ionization device arranged as shown in FIG. 9 was used. However, a 3 μm thin film was formed using the same apparatus and conditions as in the example, except that no deflection magnet was used. If=475
A, under the conditions of Va=30V and Vd=-30v, the film thickness at the center of the formed film is 0.2 μm and the Vickers hardness is 800 Kg/mm, and the film thickness on both sides is 0.5 μm and the Vickers hardness. The film thickness on both sides is 1μ and the Vickers hardness is 2500Kg/mm.
This result shows that the film thickness and hardness are not constant because the distance between the filament and anticathode is not constant.

(Effects) According to the above example, the present invention has a special structure in which the cathode hot filament and the anticathode are closely related, so that it is possible to form an excellent diamond-like film with uniform film thickness and high hardness. I understand.

3 is a cross-sectional view showing an apparatus for manufacturing a diamond-like thin film according to a second embodiment of the present invention; FIG. 3 is a plan view taken along line A-A in FIG. A similar plan view showing another example, FIG. 5 a similar plan view showing still another example of the ionization device of the present invention, and FIG. 6 a similar plan view showing another example of the ionization device of the present invention. , FIG. 7 is a similar plan view showing still another example of the ionization device of the present invention, FIG. 8 is a similar plan view showing still another example of the ionization device of the present invention, and FIG. 9 is a comparative example. FIG.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing a diamond-like thin film manufacturing apparatus according to the first embodiment of the present invention, Figure 2 is the present invention Figure 1 Figure 2 Figure 9 Procedural amendment dated August 7, 1989

Claims (9)

[Claims] (1) In a method of introducing a hydrocarbon raw material gas or a raw material gas capable of producing hydrocarbons through decomposition or reaction into a vacuum, ionizing it, and depositing it on a substrate to form a diamond-like thin film, the ionization is performed. To achieve this, a plurality of cathode heating filaments are arranged in one or multiple rows in a zigzag or straight line extending in a fixed direction at predetermined intervals, and a predetermined heating current is passed through the plurality of filaments. Production method. (2) An anticathode is provided surrounding the plurality of cathode hot filaments forming each row at a substantially constant distance, and a voltage is applied between the cathode hot filament and the anticathode. A method for producing a diamond-like thin film according to item 1 above. (3) The first method characterized in that the hydrocarbon raw material gas or the raw material gas capable of producing hydrocarbons through decomposition or reaction is introduced through a plurality of nozzles provided close to the positions of the plurality of cathode hot filaments, respectively. The manufacturing method according to item 1 or 2. (4) The method for producing a diamond-like thin film according to any one of items 1 to 3, wherein the substrate is fed in a direction substantially perpendicular to the certain direction. (5) Items 1 to 3 above, characterized in that the substrate is fixed and the plasma-like ion beam generated by ionization is sequentially deflected in a direction perpendicular to the fixed direction by the action of a variable magnetic field. A method for producing a diamond-like thin film according to any one of paragraphs. (6) In an apparatus that introduces a hydrocarbon raw material gas or a raw material gas that can generate hydrocarbons through decomposition or reaction into a vacuum, ionizes it, and deposits it on a substrate to form a diamond-like thin film, at a predetermined interval. a plurality of cathode hot filaments arranged in one or more rows in a zigzag or straight line extending in a fixed direction; and an anticathode surrounding the plurality of filaments at a substantially constant distance with respect to the plurality of filaments in each row. An apparatus for producing a diamond-like thin film, comprising means for passing a predetermined heating current through the plurality of filaments, and means for applying a voltage between the filaments and an anticathode. (7) Item 6 above, characterized in that a nozzle for introducing a plurality of hydrocarbon raw material gases or a raw material gas capable of producing hydrocarbons through decomposition or reaction is provided in close proximity to each of the plurality of cathode hot filaments. The manufacturing equipment described. (8) Items 6 to 7 above, characterized in that a means for feeding the substrate in a direction perpendicular to the certain direction is provided.
An apparatus for producing a diamond-like thin film according to any one of paragraphs. (9) Any one of items 6 to 8 above, further comprising variable magnetic field generating means for deflecting a plasma-like ion beam generated by ionization in a direction perpendicular to the fixed direction. The apparatus for producing the described diamond-like thin film.