JP3000035B2 - Method of forming graphite thin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a graphite thin film by chemical vapor deposition, and more particularly to a method for forming a graphite thin film having excellent characteristics at a low temperature.

[0002]

2. Description of the Related Art An organic compound such as benzene is thermally decomposed in the gas phase to form a graphite thin film on a substrate, thereby improving the heat resistance and corrosion resistance of the substrate, and utilizing the unique properties of the formed graphite thin film. It is recommended to do. For example, in a method of forming graphite by vapor phase growth using benzene as a raw material, high-purity hydrogen is used as a carrier gas and benzene vapor is introduced into a quartz reactor heated in an electric furnace to thermally decompose benzene. This forms a graphite thin film on the substrate. In this method, a graphite thin film is usually formed at a high temperature of 1000 ° C. or higher, and therefore, it is essential to use a material that can withstand the high temperature during formation. For this,
Substrates on which a graphite thin film can be formed have great limitations.

[0003] Graphite thin films have various peculiar properties, and their use in electronic devices, artificial superlattices, and the like has been studied. However, in the conventional method, they can be formed at a high temperature of 1000 ° C or more. Since it is necessary and much higher than the temperature allowed in the current electronic device manufacturing process, there has been a major obstacle to the development of an element utilizing the physical and electrical characteristics of a graphite thin film.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a method of forming a graphite thin film by chemical vapor deposition using an organic material as a raw material, wherein an aromatic ketone having a substituent at the ortho position of one aromatic ring is used as the organic material. This is a method of forming a graphite thin film. Further, it is a method of forming a graphite thin film in which the graphite thin film is formed on a substrate selected from cobalt, nickel, palladium, and platinum. further,
This is a method for forming a graphite thin film in which chemical vapor deposition is performed in a reactor made of alumina oxide.

That is, the method of the present invention is a method for forming a graphite thin film by chemical vapor deposition using an aromatic ketone having a substituent at the ortho position as shown below as an organic material.

[0006]

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As a substituent of these aromatic ketones, an alkyl group is preferable, and among aromatic ketones, o-
Those having a methyl group as a substituent such as methyl aryl ketones are preferred, and aromatic ketones having a relatively small molecular weight are particularly preferred. These materials have a characteristic that they can be formed at a low temperature, and can form a graphite thin film having excellent characteristics on a substrate at a temperature of about 600 ° C. Also, an aliphatic ketone such as acetone cannot form a graphite thin film at such a temperature, and similarly, an aromatic ketone having a large molecular weight cannot form a graphite thin film at a low temperature.

[0008] Graphite thin films can be formed on various substrates by the method of the present invention. In particular, when formed on cobalt, nickel, palladium and platinum, a graphite thin film having excellent crystallinity is obtained. be able to.

Further, a quartz tube is generally used for the reactor. However, when a quartz tube is used, carbon deposited by chemical vapor deposition reacts with silicon oxide. In a region where graphite grows, it is preferable to use a material containing no quartz, and it is preferable to use alumina. Also, an alumina tube may be provided inside the quartz reactor only in the chemical vapor deposition region of the quartz reactor. According to the method of the present invention, a graphite thin film having excellent crystallinity of 0.37 nm or less can be obtained.

The apparatus used for forming the graphite thin film of the present invention will be described below with reference to the drawings. A quartz tube 2 is provided inside an electric furnace 1, and an alumina tube 3 is provided inside the quartz tube.
Is provided. An aromatic ketone having a substituent at the ortho position, which is a raw material for chemical vapor deposition, is mounted on the raw material mounting portion 4 in a region outside the electric furnace of the alumina tube. A heating device 5 such as a ribbon heater is provided outside the quartz tube of the raw material mounting portion to vaporize a raw material made of an organic substance, and supplies argon as a carrier gas from an argon supply pipe 6 connected to the quartz tube, thereby forming a vaporized raw material. Into the reaction zone heated by the electric furnace,
A graphite thin film is formed on the substrate 7 while changing the temperature of the substrate 7 to 600 to 1000 ° C. The state of the growth of the graphite crystal and the plane spacing can be measured from the peak spread and the peak position of the obtained graphite thin film by an X-ray diffractometer.

[0011]

The method of forming a graphite thin film according to the present invention comprises the steps of:
Since aromatic ketones having a specific chemical structure such as methyl aryl ketone are used as a raw material and are grown on a substrate such as cobalt, nickel, palladium and platinum by chemical vapor deposition, a graphite thin film having excellent crystallinity at low temperature can be obtained. It can be formed on an electronic device using a silicon wafer or the like, and the field of application of the graphite thin film can be greatly expanded.

[0012]

The present invention will be described in more detail with reference to the following examples. Example 1 An 8 mm alumina tube was placed in an 18 mm diameter quartz tube, a nickel substrate was placed in the alumina tube, and the quartz tube was placed in the electric furnace such that the portion where the nickel substrate was placed was located inside the electric furnace. . Nickel substrate temperature 600 ~
While changing the temperature to 1000 ° C., 3 mg of o-methylarylketone having the following chemical structural formula was placed on the raw material mounting portion of the alumina tube, and the temperature of the raw material mounting portion was heated to 140 ° C. from the outside by a ribbon heater. Then, argon was supplied as a carrier gas at a flow rate of 0.3 liter / min from the raw material mounting portion of the quartz tube for 4 hours. The graphite deposited on the substrate at each temperature was stripped from the substrate, and the plane spacing in the C-axis direction of the crystal was measured by an X-ray diffractometer. 1000 ° C
FIG. 2 shows the result of X-ray diffraction of
FIG. 3 shows the measurement results of the samples obtained at each temperature of 600 to 1000 ° C. A graphite having a plane spacing close to that of the single crystal graphite was obtained.

[0013]

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Example 2 A graphite thin film was formed at 600 ° C. using the same raw materials as those used in Example 1 except that the substrate on which the graphite thin film was formed was replaced with various metals shown in Table 1. The plane spacing was measured for the obtained thin film. Table 1 shows the results.

[0015]

[Table 1]

Comparative Example 1 The procedure of Example 1 was repeated except that o-methyl aryl ketone used in Example 1 was replaced by the following aromatic aryl ketone compound 1 and condensed polycyclic aromatic compound compound 2. The temperature of the substrate was changed in the same manner as in Example 1 to form a graphite thin film. In Table 2, those in which graphite was formed are indicated by ○, and those in which graphite was not formed are indicated by x.

[0017]

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[0018]

[Table 2]

[0019]

According to the method for forming a graphite thin film of the present invention, an aromatic ketone having a specific chemical structure such as o-methylarylketone is used as a raw material and a chemical vapor is deposited on a substrate such as cobalt, nickel, palladium or platinum. It is performed by phase growth, and it is possible to form a thin film having excellent crystallinity even at a low temperature of 600 to 700 ° C., and it was impossible to use a graphite thin film in terms of the forming temperature. The present invention can be applied to a manufacturing process of an electronic device, and a new element can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a method for forming a graphite thin film of the present invention.

FIG. 2 is a graph showing the results of X-ray diffraction measurement of graphite obtained by the method of the present invention.

FIG. 3 is a diagram for explaining the relationship between the formation temperature of a graphite thin film and the surface spacing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electric furnace, 2 ... Quartz tube, 3 ... Alumina tube, 4 ... Material placing part, 5 ... Heating device, 6 ... Argon supply tube, 7 ... Substrate

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshimasa Oki 3-30-2 Ohnodai, Sagamihara City, Kanagawa Prefecture (72) Inventor Takeo Matsui 1-12-3 Ogawa, Machida-shi, Tokyo 20-202 Machida Corp Town (72) Inventor Hiroaki Kamo 7-41-5 Takinogawa, Kita-ku, Tokyo (58) Field surveyed (Int. Cl. ⁷ , DB name) C01B 31/04 101 C23C 16/26 CA (STN)

Claims (3)

(57) [Claims] 1. A method for forming a graphite thin film by chemical vapor deposition using an organic material as a raw material, wherein an aromatic ketone having a substituent at the ortho position of at least one aromatic ring represented by the following chemical formula is used as the organic material: A method for forming a graphite thin film. Embedded image 2. The method for forming a graphite thin film according to claim 1, wherein the graphite thin film is formed on a substrate selected from cobalt, nickel, palladium, and platinum. 3. The method for forming a graphite thin film according to claim 1, wherein the chemical vapor deposition is performed in a reactor made of alumina oxide.