JP2981937B2 - Synthetic method of film diamond by vapor phase method. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of synthesizing a film-like diamond by a gas phase method, and more particularly to a method of forming a film-like diamond having a uniform thickness with a high density of diamond nuclei on the substrate. Regarding the processing method.

[0002]

2. Description of the Related Art In the synthesis of vapor phase diamond, it is necessary to generate more nuclei to control the shape and homogeneity of diamond. In the growth of diamond in the vapor phase method, fine diamond nuclei are first generated at singular points on the substrate, and then the nuclei grow three-dimensionally. become. Therefore, if the nucleation density is too low, film growth does not occur. As a method of increasing the density of diamond nucleation, a scratching treatment using diamond powder or the like (the 48th Japan Society of Applied Physics,
18a-T-5) has been proposed. Also, nucleation density,
As a method for increasing the bonding strength between the diamond film and the substrate interface, etching with a chemical such as an acid or an alkali (48th JSAP Scientific Lecture, 18a-T-
4) Further, etching in a specific gas containing alcohol or the like (Japanese Patent Laid-Open No. 1-145396) is known. However, the maximum nucleation density is 10 ⁷ /
It is on the order of cm ² .

The present inventors have conducted research for the purpose of developing a method for increasing the nucleation density, and have confirmed that carbon black or graphite particles are excellent as a nucleating agent. No. 3388 (Japanese Unexamined Patent Publication No.
97). However, this method is suitable for the formation of diamond grains, but for the purpose of forming a diamond film, the uniformity of the film is insufficient and the method is not suitable for the formation of a diamond film.

[0004]

Therefore, the conditions for synthesizing a practically useful homogeneous diamond, that is, a method for growing a diamond thin film uniformly and at high speed on a substrate with high density and high adhesion strength are developed. Is strongly required.

[0005]

Means for Solving the Problems As a result of continuing research to meet the above demand, the present inventors have applied a treating agent composed of carbonaceous fine particles and an ester solvent to a substrate and used a substrate which has been heat-treated. Knowing that the goal is achieved by
The present invention has been completed. That is, in the present invention, an ester solution containing carbonaceous fine particles is applied to the substrate surface, and then the substrate is heated to 100 ° C.
The present invention also relates to a method for synthesizing film diamond by a vapor phase method, wherein a diamond synthesis raw material gas is supplied after heating at a temperature from 600 ° C. to 600 ° C.

The carbon black and soot of the present invention have a maximum particle size of 0.1 μm, preferably 0.005 to 0.07 μm.
It is. The heating time is not particularly limited, but is practically one to several hours. Specifically, the ester solvent and the carbonaceous fine particles are combined by heating, and are dispersed and scattered as carbon compound particles on the substrate.

When a gas phase method diamond synthesis reaction is carried out using such a gas, the probability of attachment of the diamond precursor radical to the carbon compound particles is increased, the diamond nuclei are easily formed, and the nucleation density is reduced by the conventional method. As compared with the above, the adhesion strength of the produced diamond to the substrate becomes large, and the film thickness becomes extremely uniform.

Acetate is specifically used as the ester solution, and a commercially available marker is particularly preferred for practical use. The amount of carbonaceous fine particles in the ester solution is equal to the amount of ester 1
The range of 1 mg to 0.3 g in 00 cc is preferable.

[0009]

According to the present invention, it is possible to form a uniform diamond film in the vapor phase method.

[0010]

Examples [Examples and Comparative Examples] Next, the present invention will be described with reference to Examples and Comparative Examples. Example Carbon black particle size of 0.01 to 0.05 μm was adjusted to 100
An ester solution containing 10 mg in cc (actually, a commercially available white plate marker) was uniformly applied to the surface of a 25 mm square silicon wafer. This silicon wafer was heated at 250 ° C. for 2 hours using a conventional hot filament diamond synthesizing apparatus (diameter 25).
cmφ × height 20cm), 90 torr, H ₂
The treatment was performed in an atmosphere of 100 cc / min and ethanol at 3 cc / min. The distance between the silicon wafer substrate and the hot filament was set to 5 mm, and gasified ethanol as a raw material was introduced into the reaction furnace through a supply port at 3 cc / min and hydrogen at 100 cc / min, and diamond deposition was performed at a pressure of 90 torr for 2 hours. The reaction continued. Diamond particles having an average of 0.5 μm are deposited at high density on the substrate to form a film. Diamond was confirmed by optical microscopy and Raman spectroscopy. The diamond nucleation density was determined by the S
It was determined from the value calculated from the EM photograph. The result is 5 × 10 ³
/ Cm ² . FIG. 1 is an SEM photograph (200 magnifications) of a deposited diamond film formed two hours after the start of synthesis.
Times).

Comparative Example 1 Diamond synthesis was performed under all the same conditions except that the ester solution was not applied to the silicon wafer and the heat treatment was not performed. After the synthesis, 5 to 8 μm grains were scattered on the substrate.
FIG. 2 is an SEM (200 times magnification) of the precipitated diamond particles 2 hours after the start of the synthesis. Nucleation density is about 1
0 ³ / cm ² to 10 ⁴ / cm ² . Comparative Example 2 A graphite electrode was ground with sandpaper, and the obtained powder having a diameter of submicron to several μm was dispersed in ethanol and applied to the surface of a silicon wafer in the same manner as in the example. Thereafter, the wafer was heat-treated exactly as in the example. A diamond synthesis reaction was performed under the same conditions as in the examples. As a result of observation on the silicon wafer after the completion of the reaction, it was confirmed that the diamond-like carbon slightly aggregated in the massive aggregate of diamond-like carbon in a nonuniform state. The nucleation density is 10 ¹ / cm ² to 10 ³ / c.
It was m ^2.

[Brief description of the drawings]

FIG. 1 is a 200 × SEM micrograph of a deposited diamond thin film 2 hours after the start of synthesis in an example.

FIG. 2 is a 200 × SEM micrograph showing the particle structure of precipitated diamond 2 hours after the start of synthesis in Comparative Example 1.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C30B 1/00-35/00

Claims (1)

(57) [Claims] In a method of depositing a film-like diamond on a substrate by a gas phase method, an ester solution containing carbon black or soot is applied to the substrate surface, and then the substrate is heated at 100 to 600 ° C. A method for synthesizing film-like diamond by a gas phase method, characterized by supplying