JPH0526869B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for producing a transition metal carbide film.

(Prior Art) Generally, carbides have high hardness, wear resistance, and corrosion resistance, and are widely used as coating films for metals or metal alloy materials.

Such carbide coatings, especially metal carbide coatings, are usually made by chemical treatment using a saturated fatty acid hydrocarbon such as methane or propane as a carbon source and a compound such as titanium tetrachloride or tungsten hexafluoride as a metal source. This is done using the vapor phase growth method (CVD method).

However, in the above-mentioned coating method, the thermal decomposition temperature of the raw material gas used is high, and the treatment must be performed at a temperature exceeding 1000°C, for example, resulting in a decrease in the performance of the metal base material.

Methods of processing without raising the temperature of the base material, such as ion plating and sputtering methods, are being considered, but these all use physical adhesion and do not cause any damage between the base material and the coating layer. Its strength is extremely low, making it unsuitable as a coating. Furthermore, the coating itself has almost no crystallinity, and its hardness, corrosion resistance, etc. are inferior.

(Object of the Invention) The present invention has been made in view of the above-mentioned conventional methods, and uses a pyrolytic CVD (chemical vapor deposition) method.
The purpose of the present invention is to provide a technology for forming a carbide film with excellent crystallinity on a substrate at a relatively low temperature of 1000°C or less.

(Contents of the invention) That is, the present invention involves simultaneously introducing vapors of an unsaturated group-containing hydrocarbon compound and a transition metal halide, and thermally decomposing them at 600 to 1000°C to form a transition metal carbide film on a substrate. Provided is a method for producing a transition metal carbide film characterized by the following.

In order to synthesize a transition metal carbide, the present invention utilizes a simultaneous thermal decomposition method of an unsaturated group-containing hydrocarbon compound and a transition metal halide, and uses a hydrocarbon compound with a low thermal decomposition temperature.
It is possible to form a carbide film with excellent crystallinity at a low temperature of 400°C, exceeding the lower limit of the conventional practical processing temperature.
or more.

The unsaturated group-containing hydrocarbon compounds used in the present invention include aromatic hydrocarbons such as benzene, toluene, xylene, naphthalene, α-methylnaphthalene, etc.; unsaturated fatty acid hydrocarbons such as ethylene,
Propylene, butylene, 2-butyne, acetylene, etc.; diene compounds, such as butadiene, isoprene, etc.; or halogen-substituted products thereof, such as p-chlorobenzene, 1,2-dichloroethylene, 1,2-dibromoethylene, etc.

Examples of transition metal halides include titanium tetrachloride, vanadium tetrachloride, chromium hexafluoride, tungsten hexafluoride, molybdenum hexafluoride, and technetium hexafluoride.

The method for producing a transition metal carbide film of the present invention will be explained based on drawings and examples.

(Embodiment) FIG. 1 is a block configuration diagram of a carbide generating apparatus for explaining an embodiment of the present invention.

The above two types of raw material gases are diluted with a carrier gas and introduced into the quartz reaction tube 4. The raw material is supplied to the quartz reaction tube 4 using an ordinary pressure bubbler method or a reduced pressure method. In either method, a carbide with excellent crystallinity can be obtained by controlling the supply amount of each raw material as described below. In the atmospheric bubbler method, hydrogen or argon gas is used as a carrier gas. Although FIG. 1 shows an apparatus configuration that uses the normal pressure bubbler method, it is also possible to use the reduced pressure CVD method with this apparatus. In this case, it is possible to achieve a more uniform carbide film thickness than in the normal pressure bubbler method.

The amount of raw material supplied strongly depends on the type of unsaturated group-containing hydrocarbon compound and transition metal halide used, but it is desirable to reduce the concentration of the hydrocarbon compound as the reaction temperature increases. For example, when benzene and titanium tetrachloride are used, it is effective to adjust the concentration of benzene as shown below depending on the reaction temperature.

For one volume of titanium tetrachloride (gas), benzene is 10 to 20 volumes at 800 to 900℃, and 5 to 20 volumes at 900 to 1000℃.
It is 10 volumes. If the supply amount is set above this concentration ratio, the surface unevenness of the obtained titanium carbide becomes severe and sooting occurs.

Argon gas is supplied from the argon gas control system 2 into the bubble containers 1 and 1' containing benzene and titanium tetrachloride that have been purified by vacuum distillation, and the benzene and titanium tetrachloride are bubbled independently. Benzene molecules and titanium tetrachloride molecules are simultaneously fed to the quartz reaction tube 4 through the Tx glass tube 3. At this time, the temperatures of liquid benzene and liquid titanium tetrachloride in the bubble containers 1 and 1' are kept constant, and the argon gas flow rate is adjusted independently with the valve 5. The amount of supply into each tank is controlled at a constant level. On the other hand, argon is flowed through the dilution line 9 to optimize the number density and flow rate of the benzene molecule and titanium tetrachloride mixed gas fed to the reaction tube 4. A sample stage 7 on which a growth substrate is mounted is installed in the reaction tube 4, and a heating furnace 8 is provided around the outer periphery of the reaction tube 4. The growth substrate in the reaction tube 4 is maintained at a relatively low temperature of 1000° C. or less by the heating furnace 8 .

The mixed gas of benzene and titanium tetrachloride introduced into the reaction tube 4 is heated to a temperature of 1000° C. or less, and each gas is simultaneously thermally decomposed. On this occasion,
Titanium and carbon atoms produced by pyrolysis react to form titanium carbide, which has a lower free energy.

As a result of elemental analysis using an X-ray microanalyzer, it was confirmed that the titanium carbide thin film obtained had a stoichiometric composition. Further, as a result of high-speed reflection electron diffraction, it was confirmed that at a reaction temperature of 900 to 1000°C, the concentration ratio of benzene to titanium tetrachloride transitioned from polycrystal to single crystal in the range of 5 to 10.

Note that similar results can be obtained by using other low-melting-point halides other than titanium tetrachloride as transition metal halides that form carbides, and combinations with other hydrocarbon compounds other than benzene can also be used. is also possible.

(Effects of the Invention) As described above, according to the carbide synthesis method according to the present invention, synthesis can be performed at a lower reaction temperature than conventional methods using the pyrolysis CVD method. A carbide film with excellent crystallinity can be formed without impairing performance.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a carbide generating apparatus for explaining an embodiment of the present invention. 1, 1'...Bubble container, 2...Argon gas control system, 3...Glass tube, 4...Reaction tube, 6,9
...Dilution line, 7...Sample stand, 8...Heating furnace.

Claims (1)

[Claims] 1. Steam of an unsaturated group-containing hydrocarbon compound and a transition metal halide is introduced at the same time, and
A method for producing a transition metal carbide film, which comprises forming a transition metal carbide film on a substrate by thermal decomposition at °C.