JPH03141110A - Production of product in steric shape made of diamond - Google Patents

Abstract

PURPOSE:To improve quality of a diamond film product by thermally spraying silicon onto the surface of a substrate in a steric shape, then dissolving and removing the substrate, providing a silicon self-supporting substance and subsequently forming a CVD diamond film on the self-supporting substance. CONSTITUTION:Silicon is thermally sprayed onto the surface of a substrate in a steric shape and the substrate is then dissolved and removed to provide a silicon self-supporting substance (e.g. a silicon substrate 6). A CVD diamond film is subsequently formed on the self-supporting substance (e.g. in a CVD chamber 1). Al, Cu, Fe or alloy thereof and high polymer materials, etc., dissolvable and readily removable are preferably used as the above-mentioned substrate in the steric shape. The silicon self-supporting substance is further dissolved and removed with hydrofluoric acid. If the silicon self-supporting substance (e.g. the silicon substrate 6) is dissolved in a chemical, a diamond container of a self-supporting thin film without any cracks is stably obtained.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides various high-purity Li! The present invention relates to a method for producing +mi2 of diamond three-dimensional shaped products such as containers that can be used for melting and purifying reagents and high-purity glass, and is particularly suitable for producing fluoride glass.

[Conventional technology]

Diamond has the highest hardness on earth, has a small coefficient of thermal expansion, and has high thermal conductivity (and is not attacked by almost all chemicals except in high-altitude oxidizing atmospheres). Although natural diamonds have many properties, even industrial diamonds are expensive and large single-crystal diamonds cannot be obtained.Also, large diamonds can be obtained artificially using static high-pressure methods. It is difficult to make something larger than one strength rat, and the cost of making it is said to far exceed that of a natural one.Therefore, there is a limit to its size, and it is also difficult to process due to its high hardness. However, in order to use diamond as a component, there were major restrictions not only on size but also on shape.

To solve the above-mentioned problems, in order to obtain a diamond product with a three-dimensional shape such as a container, a CVD diamond film is formed on the surface of a heat-resistant base material of the same shape, and then the base material is dissolved and removed. We manufacture diamond parts with complex shapes by
')e [Problem to be Solved by the Invention] However, when diamond with a curved surface is deposited using a material such as molybdenum or titanium, which has a significantly different coefficient of thermal expansion from diamond as a base material, cracks are likely to occur in the diamond film.

On the other hand, silicon is an excellent material as a base material because diamond is easily precipitated by CVD and the difference in thermal expansion is small compared to diamond.

Therefore, a silicon wafer or the like is used as the base material.

However, if it is a flat shape like a silicon wafer, there is no problem, but if it is a three-dimensional shape, the M-wall processing is poor, resulting in low yield and high cost.

Therefore, in the above-mentioned Japanese Patent Application Laid-open No. 1-138111, silicon is sprayed onto a quartz container and used as a base material for diamond production (example).

However, even if diamond is precipitated with silicon sprayed in this container, the stress caused by the difference in thermal expansion with quartz is not sufficiently alleviated, and the diamond may crack or become free-standing. It turns out that changes occur.

The object of the present invention is to provide a silicon base material at a low cost, improve the amount of diamond produced, and obtain a high-quality diamond film product.

(Means for solving the f1 problem) The present invention has been made to achieve the above-mentioned object, and its gist is to inject +8 silicon onto a three-dimensional substrate,
Next, the silicon free-standing body is obtained by removing the lli base material by a method such as dissolution. A method for using a three-dimensional diamond container includes forming a CVD diamond film on the obtained silicon self-supporting body as a base material, and further dissolving and removing the silicon base material if necessary.

Base materials for thermal spraying silicon include At, Cu, and F.
e or those alloys and polymer materials that can be thermally sprayed, 1ffl! It is desirable that the base material 11 be removable, and its shape is not particularly limited as long as it has a three-dimensional shape such as a container, a pipe, a speaker lens, etc. A silicon film is formed on this base material by thermal spraying.

For the formation of the film, thermal spraying is most suitable from the viewpoint of productivity, and the film thickness is suitably 20 to 100 μm from the viewpoint of practical strength and economic efficiency.

The present invention is characterized in that after forming this film, the base material is removed to obtain a silicon free-standing body, which is used as a base material for CVD diamond.

Removal of the base material can be performed, for example, by a dissolution method using a solution that dissolves only the base material without T8 decomposition of the silicon.

A well-known method such as a microwave plasma method or a hot filament CVD method can be used to generate CVD diamond on a silicon free-standing body.

After diamond formation, use hydrofluoric acid if necessary? Remove the silicon by a method such as adding 8 m. As a result, it is also possible to produce products made only of diamonds.

Taking the case of obtaining a diamond container as an example, the IT
The present invention will be specifically explained using FIG.

Figure rE1 shows an example of a hot filament CVD apparatus, and reference numeral 1 in the figure is a CVD chamber in which CVD diamond is produced. Connected to the CVD chamber 1 are a hydrogen cylinder 2 that supplies hydrogen for dilution, and a hydrocarbon 3 that supplies hydrocarbons that are raw materials for carbon. Also, CVD room 1
Maintain a reduced pressure inside 1! ? A pressure gauge 5 for reading the pressure inside the CVD chamber 1 is attached. Inside the CVD chamber 1, a support body 7 is provided which supports a container-shaped silicon substrate 6 with its opening facing upward.
This support 1hikyu 7 is rotated at a predetermined speed by a rotary drive machine 8 provided outside the CVD chamber 1. Further, a filament 10 for irradiating an electron beam is provided close to the inner surface of the base material 6, and a voltage adjustment ff1 is provided.
139.

Note that 11 is a flow meter, 12 is a valve, and 13 is a bubbler.

The hydrocarbons used in the above CVD equipment include aliphatic hydrocarbons such as methane, ethane, and propane, benzene,
Aromatic hydrocarbons such as toluene, ethanol, and oxygen-containing organic compounds such as acetone are used. These gases are hydrogen at 0.1-50v.

It is diluted to 1% and 10 to 1 by oil rotary pump 4.
It is introduced into a CVD chamber maintained at 00 Torr.

While rotating the base material 6, the filament 10 is
When heated to ~2200°C to emit thermoelectrons, the portion of the base material 6 facing the filament reaches a temperature of 700~1000°C.
The base material 6 is heated to a temperature of 10.degree., and diamond is precipitated on the inner surface of the base material 6, forming three diamond films.

When the surface-formed diamond film on the base material 6 has reached the desired height, remove it and dissolve the base material 6 with chemicals to create a diamond container with a self-supporting film without cracks. was stably obtained, as disclosed in JP-A-1-138111.
The yield is significantly improved compared to the previous method.

The surface properties of the diamond container obtained by this method are as follows:
It is almost the same as a natural diamond. In other words, film-like diamond is obtained in the form of polycrystals, so when measured by X-ray diffraction spectroscopy, (11,1) and (220) planes unique to q-gonal diamond were observed, and the Raman spectrum showed 1332 crn -', which is similar to diamond. A sharp peak indicating the presence of the component was observed.

In the above explanation, diamond is deposited on the inner surface of the container-shaped base material, but as shown in FIG. 2, diamond may be deposited on the outside of the base material 6. Do it like this.

Next, we will show examples and book 5! A method for manufacturing diamond products related to this invention will be explained.

[Example 1] Inner diameter 30 mm, l'X length Q, 8+nm, depth 2
Silicon was thermally sprayed at 200 pm Jrl onto the inner surface of a 0 mrn aluminum crucible, and the surface was polished (R
IIax) After forming a silicon film of approximately 18 μm,
Aluminum is removed with hydrochloric acid diluted to 20vQ1% with pure water to obtain silicon self-supporting material. Using this self-supporting film as a base material, diamond was deposited using the apparatus shown in FIG. 1 having a CVD chamber capacity of 6.5 cm. As a filament,
A tungsten wire with a diameter of 0.3 mm was used and was centered to match the inner surface of the base material. The distance between the filament and the surface of the base material was always 2±0.5 mm. Heat the filament and heat the surface of the base material facing the filament to 85
It was kept at 0°C.

f'! As the X source gas, methane diluted to 1vol% with hydrogen was used, and the CVD chamber pressure during deposition was 30 Torr.
was introduced at a rate of 1503 CCM.

After diamond was deposited for 300 hours at a rotational speed of 0.2 rph, the base material was taken out.

The base material was subjected to R8 decomposition with boric acid to obtain a diamond exhibition container. By weighing this weight, the average film thickness was found to be 50μ.
It was m.

In order to confirm the impermeability of this container, fA sulfuric acid was placed in the container, floated on pure water, and changes in the pure water after 1 hour were examined, but no significant changes were observed.

In addition, when the container was boiled with hydrofluoric acid and the eluted components were examined using an inductively coupled plasma emission spectrometer, it was found that transition metals such as tungsten
No components were detected.

Furthermore, as a result of measuring this container by Raman spectroscopy and X-ray diffraction, it was confirmed that it was diamond.

When similar experiments were repeated 20 times, the yield was 95%, and when a diamond container without deformation or a (4) was made, the yield was about 50%.

[Example 2] Inner diameter 50 mm, thickness 1. On the inner surface of an aluminum IIQ container with a depth of 30 mm, silicon was sprayed to form a silicon film with a surface roughness (Rmax) of about 18 lt m, and the average IIQ was heated in the same manner as in Example 1.
! 11 diamond containers each having a thickness of 80 μIn were prepared.

Using this container, high purity NaF for fluoride optical fiber was produced. High purity N a F 1. A method in which metal impurities are removed by a solvent extraction method and then precipitated by adding hydrofluoric acid (Kobayashi, Terunuma, Itame, 1986, Autumn, Vol. 4)
7th Japan Society of Applied Physics Academic Lecture.

The lecture preview (^ collection, page 182, lecture number 27a-X-2) was used. The obtained NaF was multiplied by the radial fraction. The results are shown in Table 1.
Shown below.

The analytical value of NaF produced from the same compound using a platinum crucible is also listed.

Table 1 A diamond film was deposited to obtain a speaker diaphragm having an average film thickness of 40 μm. The physical properties of this diaphragm are shown in Table 2. The sound velocity and internal In loss of the diamond diaphragm are larger than those of titanium and beryllium, which have been conventionally used as diaphragms, and can be used as a superior diaphragm.

As is clear from the first length of Table 2, when a diamond crucible is used, the purity is higher than when a platinum crucible is used.

[Example 3] Silicon was thermally sprayed on the inner surface of an aluminum container with an inner diameter of 25 mm, a thickness of 0.8 mm, and a depth of 6 mm in the same manner as in Example 1, and the silicon had a surface roughness (Rmax) of about 18 μm. The membrane was made free-standing and used as a base material.

Using this base material, the inner surface was coated in the same manner as in Example 1. [Effects] As described above, according to the present invention, free-standing diamonds can be obtained at a high production rate, and therefore, from an economic point of view, diamonds are superior to diamonds. Due to its properties, it can be used as a substitute for platinum in refining high-purity metals, melting fluoride glasses, etc. Therefore, these 8 sushi, which conventionally had to use platinum products, can greatly contribute to industry by reducing the manufacturing cost of high-purity materials.

[Brief explanation of the drawing]

Figure m1 is a diagram of the CVD apparatus used in the present invention, and Figure 2 is a diagram of the CVD apparatus used in the present invention.
FIG. 3 is a diagram showing the relative positions of a base material and a filament when diamond is deposited on the outer surface of a container-shaped base material. 1...CVD chamber, 2...Hydrogen cylinder, 3...Hydrocarbon cylinder, 4...7111 transfer positive, 5...Pressure needle, 6...Silicon base material, 7...Support Body, 8...
times? 2 Drive machine 9... Voltage regulator, 10... Filament, 11... Flow meter, 12... Valve, 13
...Bubbler Figure 2

Claims (1)

[Claims] A diamond three-dimensional structure, characterized in that silicon is thermally sprayed onto the surface of a three-dimensional base material, the base material is then removed by a method such as melting to obtain a silicon free-standing body, and a CVD diamond film is formed on this free-standing body. Method of manufacturing shaped products.