JPH10236898A - Diamond synthesizing method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a diamond having high density, large thickness and good quality with good reproducibility without keeping a substrate at high temp. by irradiating a solidified target substance prepared by solidifying a fluid substance containing at lest C and H atoms with synchrotron radiation light to cause ablation so as to produce diamond on a substrate. SOLUTION: A fluid substance in a gas or liquid state containing at least C and H atoms (such as acetone) is solidified on a holding mount 4 cooled by a cooler 11 to produce a solidified target substance 3. The solidified target substance 3 is irradiated with synchrotron radiation light 5 produced by a synchrotron device 6 to cause ablation so as to produce diamond on a substrate 7 sch as quartz disposed to face the holding mount 4. By irradiating the target with laser light before irradiating with synchrotron light 5, ablation is further accelerated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for synthesizing diamond using synchrotron radiation (hereinafter abbreviated as "SR light") and an apparatus therefor.

[0002]

2. Description of the Related Art As a conventional technique for artificial synthesis of a diamond of this type, there is a method disclosed in Japanese Patent Application Laid-Open No. Hei 6-24896 as a typical method using laser light, and uses laser ablation. As a typical method, there is a method disclosed in JP-A-6-234594. The method disclosed in the former publication is a method of synthesizing diamond on a substrate in a gas phase using a raw material gas in which a compound containing a carbon atom is diluted with hydrogen gas. A method in which the compound and hydrogen gas are decomposed by irradiating in a gas or on the substrate to synthesize diamond on the substrate.
Further, the method disclosed in the latter publication is a method of forming a diamond thin film by scattering carbon particles by laser ablation on a graphite target provided in a reaction chamber and reacting the carbon particles by a photochemical reaction on a substrate. It is.

[0003]

The method disclosed in the former publication is a gas phase synthesis method based on photolysis of a raw material gas by laser light, and therefore has a problem that reproducibility is not good. Further, there is a problem that a diamond peak at 1333 cm ^-1 in Raman spectroscopy is difficult to appear. In addition, there is a problem that the substrate temperature must be maintained at a high temperature. In addition, the method disclosed in the latter publication uses laser ablation generated by irradiating a target made of graphite with laser light, so that the density of diamond nucleation is low, rather than forming a thin film. There is a problem in the film quality that a mass of particles is generated. Further, there is a problem that it is necessary to irradiate the substrate with SR light, and if the substrate is not heated to a high temperature by a heat source, the efficiency of diamond synthesis is reduced.

[0004]

Means for Solving the Problems The present invention has been made in view of the above circumstances.
According to the first aspect, a solidification target material obtained by solidifying a gaseous or liquid fluid material containing at least carbon and hydrogen atoms is irradiated with SR light to generate ablation, thereby producing diamond on a substrate. The diamond synthesis method is used. According to a second aspect of the present invention, there is provided a diamond synthesizing method according to the first aspect of the present invention, wherein a laser beam is irradiated, and then SR light is irradiated to generate ablation. Claim 3
In the method, the ablation is performed in the presence of a gas containing nitrogen, boron, or the like.

According to a fourth aspect of the present invention, there is provided a reaction chamber, a supply device for supplying a gaseous or liquid fluid substance containing at least carbon and hydrogen atoms into the reaction chamber,
A coagulation apparatus for coagulating the supplied gaseous or liquid fluid material to form a coagulation target material, a holding table for holding the coagulation target material in a reaction chamber, and a coagulation target held by the holding table SR for substance
A diamond synthesizing apparatus includes a device for irradiating light and a substrate for generating diamond provided in the reaction chamber so as to be opposed to ablation caused by the irradiation with SR light. According to a fifth aspect of the present invention, there is provided a diamond synthesizing apparatus according to the fourth aspect, wherein the solidifying target material held by the holding table is irradiated with laser light and SR light.

According to a sixth aspect of the present invention, a reaction chamber, a holding table for holding a solidified target material obtained by solidifying a gaseous or liquid fluid material containing at least atoms of carbon and hydrogen in the reaction chamber, and a holding table for holding the solidified target material A device for irradiating the solidification target material held on the table with SR light,
A diamond synthesizing apparatus includes a diamond generation substrate provided in the reaction chamber so as to face the ablation caused by the SR light irradiation. According to a seventh aspect of the present invention, there is provided a diamond synthesizing apparatus according to the sixth aspect, wherein the solidifying target material held by the holding table is irradiated with laser light and SR light. Further, in claim 8, a diamond synthesizing apparatus in which a gas containing nitrogen, boron or the like exists in the reaction chamber.

[0007]

Embodiments of the present invention will be described. In this diamond synthesis method, a solidification target material obtained by solidifying a gaseous or liquid fluid material containing at least carbon and hydrogen atoms is irradiated with SR light to generate ablation, thereby producing diamond on a substrate. The diamond synthesis method is used. As a first embodiment of a diamond synthesizing apparatus embodying this method, as shown in FIGS. 1 and 2, a reaction chamber 1 and a gaseous state containing at least carbon and hydrogen atoms in the reaction chamber 1 are used. Alternatively, an SR having a holding table 4 for holding a solidification target material 3 obtained by solidifying a raw material 2 which is a liquid fluid substance, and an SR light source for irradiating the solidification target material 3 held on the holding table 4 with SR light 5 An apparatus 6 and a substrate 7 for diamond generation provided in the reaction chamber 1 so as to face the ablation caused by the irradiation of the SR light 5;
Is ejected to the upper side of the holding table 4 through the raw material supply pipe 8 so as to be introduced.

Materials containing at least carbon and hydrogen atoms as the raw material 2 include paraffin hydrocarbons (C _n H _{2n + 2} ) such as methane, olefin hydrocarbons (C _n H _2n ) such as ethylene, and acetylene. Acetylene hydrocarbon,
Examples include alcohols such as methanol, ethers such as methyl ether, aldehydes such as methanal, ketones such as acetone, and aromatic compounds such as benzene. These are substances whether they are gaseous or liquid,
Alternatively, a solid or powdered material may be dissolved in a solvent to make a liquid, or a mixture of a gas and a liquid may be used. In short, a fluid of any of the above substances, which is a gas, a liquid or a mixture of a gas and a liquid, can be used as a raw material of the present invention.

The holding table 4 is connected to a cooler (coagulator) 11 which is cooled by a refrigerant 10 supplied through a refrigerant supply pipe 9 so as to be able to conduct heat, so that it is easy to maintain a low temperature state. . As the refrigerant 10, one selected from liquid nitrogen, liquid helium, dry ice, ice, and the like that is appropriate for the solidification temperature of the raw material 2 is appropriately used. Although the cooler 11 is described as being directly cooled by the refrigerant 10, the cooler 11 may be cooled by other means, for example, a refrigeration or a cooler. The holding table 4 is preferably made of a metal plate having good thermal conductivity, for example, copper or stainless steel, but may be made of another material. The holding table 4 and the cooler (solidification device) 11 may be formed separately as in this embodiment, or may be formed integrally so that one also serves as the other. It is included in.

[0010] Opposite to the holding table 4, a substrate 7 for producing diamond made of silicon, quartz, a metal plate or the like is provided in the reaction chamber 1.
Diamond is generated on the surface facing the holding table 4. In the present invention, diamond is generated even if the substrate 7 does not maintain the high temperature state by the heat source 12,
A heat source 12 may be provided to control the film quality and increase the production efficiency.

The inside of the reaction chamber 1 is decompressed and maintained in a vacuum state by an exhaust device 13 such as a turbo molecular pump so that ablation easily occurs.
However, it is possible to synthesize diamond by ablation of SR light even in oxygen.
Is not indispensable, but there is an advantage that the generation efficiency is improved if used. The SR light 5 emitted from the SR device 6 is
When the solidified target material 3 is irradiated with the light passing through the converging mirror 14, the ablation has the advantage of being efficiently generated. However, even when the light is not passed through the converging mirror 14, the ablation can be sufficiently generated. It is not a mandatory requirement.

Unlike the laser light, the SR light 5 emitted from the SR device 6 has a characteristic that the wavelength is continuous light and the phase is different. However, it is possible to cause an inner-shell electron excitation reaction in a substance irradiated with soft X-rays and vacuum ultraviolet rays shorter in wavelength than laser light. Further, the photon flux that represents the amount of light passing through a unit area in a unit time ^{(phs./sec · mA · mm 2 ·} 0.1% bw) is a "threshold" value greater than that allowed to rise to ablation coagulation target material Must-have. For this purpose, it is necessary to increase the amount of electrons stored in the SR
The distance from the apparatus 6 to the target material is made as short as possible to increase the value of the photon flux. Also, a condenser is provided in the beam line to increase the photon flux per unit area. Achieving a high flux density in this way is a requirement for a light source that generates SR ablation.

Next, a process of synthesizing diamond using the above-described apparatus will be described. First, a gaseous or liquid fluid material containing at least carbon and hydrogen atoms, which is the raw material 2, is jetted through the raw material supply pipe (supply device) 8 onto the upper surface of the holding table 4 cooled by the cooler 11. . Then, the raw material 2 solidifies on the upper surface of the holding table 4. At this time, when the raw material 2 is a gas, it coagulates like frost, and when it is a liquid, it coagulates like ice to become a coagulation target material 3. When the solidification target material 3 is irradiated with the SR light 5 having a photon flux light amount larger than the threshold value, bond cleavage is explosively caused on the surface of the solidification target material, thereby forming a decomposed piece. A phenomenon in which carbon, carbon-containing radicals and hydrogen enter a plasma state and scatter at supersonic speed with light emission, that is, ablation occurs, and the scattered debris and carbon deposit and grow on the substrate, and the diamond A film is created.

In the case of the present invention in which the target material is a solidified gaseous or liquid fluid material containing at least carbon and hydrogen atoms, the irradiation of the SR light 5 causes carbon to be converted into atomic and molecular units. In the case of a conventionally used solid such as graphite, bond cleavage occurs only in atomic units, so that the solidification target material 3 is substituted. Even when used as a raw material, generation of diamond does not occur. Hydrogen required for diamond production is supplied from outside.

In the first embodiment, the raw material 2 is continuously supplied to the upper surface of the holding table 4 to compensate for the solidified target material 3 reduced by the ablation. As a result, a thick film of diamond can be formed on the substrate 7.

When the raw material 2 is a liquid or a mixture of a liquid and a gas, it takes some time to freeze and solidify on the upper surface of the holding table 4. There is a risk of leakage from the top surface. In order to prevent this, it is desirable that the periphery of the upper surface of the holding table 4 is surrounded to form a container.

Next, an apparatus according to a second embodiment for realizing the method of the present invention will be described with reference to FIG. The difference from the first embodiment described above is that, as is clear from the figure, a lump of the solidified target material 4 which has been frozen and solidified in advance like ice is placed on the upper surface of the holding table 4.
That is, the raw material supply pipe 8, the refrigerant supply pipe 9, and the cooler 11 become unnecessary.

According to the diamond synthesizing apparatus of the second embodiment, the solidification target material 3 is placed on the upper surface of the holding table 4, and the ablation ends when the total mass of the solidification target material 3 has disappeared. The thickness of the diamond film to be deposited depends on the solidification target material 3 placed first.
Only for

Even in this embodiment, if the holding table 4 is cooled, it is possible to prevent the solidification target material 3 from melting, so that it is effective when the ablation time is long. is there.

The solidification target material 3 is placed on the holding table 4.
May be continuously supplied by the supply device. In this case, the generation of ablation can be continuously continued for a long time. Generation can be expected.

In the first and second embodiments described above, S
If the solidified ablation material is activated by irradiating the laser light before the R light irradiation, the ablation by the SR light is more actively performed, so that diamond can be efficiently generated. In this case,
As with the device for irradiating SR light, a device for irradiating laser light is separately provided.

In the first and second embodiments described above, if gases such as nitrogen and boron are introduced into the reaction chamber 1, these gases and carbon generated by ablation act on the substrate 7. Since a p-type semiconductor diamond film is deposited on the substrate, this method can be adopted as necessary. Also in this case, a necessary amount of gas such as nitrogen or boron may be continuously supplied from outside the reaction chamber 1 by a supply pipe or the like.

[0023]

[Experimental equipment, explanation of premise]

(1) As the SR device as the SR light source, a superconducting small SR device (in the Ritsumeikan SR Center) was used. The relationship between the photon flux and wavelength (photon energy) of this light source is as shown in FIG. That is, the wavelength includes a vacuum ultraviolet ray and a soft X-ray, and is a region in which an inner-shell electron excitation reaction of the irradiated substance occurs, and the photon flux has a high flux density that can generate SR ablation. The beam line used was the BL-14 white light irradiation beam line of the above SR apparatus. In this beam line, the light beam radiated from the light source point is condensed (vertically) and guided to the position of the solidification target material on the upper surface of the holding table of the reaction chamber.
Further, the SR light was used in a state of white light without selecting a wavelength by a spectroscope. (2) The reaction chamber has a diameter of 20 cm and a vertical length of 25.
cm. (3) Gaseous acetone was used as a raw material. (4) Liquid nitrogen was used as the refrigerant. (5) A 10 mm × 15 mm quartz substrate was used as the substrate. The distance from the solidification target material to the substrate is 1
0 mm. (6) A turbo molecular pump was used as the exhaust device.

[Experimental conditions] (1) SR light was irradiated with white light having a wavelength in the range from soft X-rays to visible light for 60 minutes. (2) The raw material acetone was supplied to the upper surface of the holding table at a rate of 0.1 to 0.2 cc / min. (3) The substrate was kept at room temperature without heating. (4) Liquid nitrogen was used as the refrigerant. The temperature of the holder was always maintained at -80 ° C. As a result, acetone solidified like frost on the upper surface of the holding table. (5) The degree of vacuum in the reaction chamber was 2 × 10 ⁻⁶ Torr.

[Experimental Results] During the experiment, plasma was observed from the window of the reaction chamber. After the experiment was completed, the thickness of the thin film formed on the substrate was measured.
m, 150 nm at thick portions. When this thin film was subjected to Raman spectroscopy, it showed a Raman spectrum as shown in FIG. In FIG. 5, 133
Since a diamond peak occurs at 3 cm ^-1 ,
It was confirmed that the formed thin film was a diamond film.

[0026]

According to the method and apparatus for synthesizing a diamond according to the present invention, compared with the conventional method using laser light or laser ablation, it is possible to synthesize at room temperature without having to raise the temperature of the substrate. In addition, there is an advantage that the device can be used. In addition, there is an advantage that the produced diamond can have high density and good quality. Further, since a gaseous or liquid fluid material containing at least carbon and hydrogen atoms as a raw material can be a gas or a liquid, there is an advantage that the range of selection of the raw material is widened.

In addition, since the raw material has fluidity, as shown in the first embodiment, continuous supply through a supply pipe or the like to the reaction chamber becomes possible. , The efficiency of the synthesizing operation can be improved, and large diamonds can be produced.

When a solidified target material obtained by freezing and solidifying a liquid material is used, there is an advantage that diamond can be synthesized with a simpler apparatus as shown in the second embodiment.

Further, if laser light is irradiated before the SR light, there is an advantage that ablation is easily generated by the SR light, and the efficiency of diamond generation is improved.

Further, if ablation is performed in an atmosphere of a gas such as nitrogen or boron, there is an advantage that a p-type semiconductor diamond useful for the semiconductor industry can be synthesized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an apparatus according to a first embodiment of the present invention.

FIG. 2 is an enlarged explanatory view of a main part of FIG. 1;

FIG. 3 is an enlarged explanatory view corresponding to FIG. 2 of a second embodiment of the present invention.

FIG. 4 is a graph showing the relationship between photo flux and photon energy.

FIG. 5 is a graph of Raman spectroscopic analysis results of a thin film formed on a substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction chamber 2 Raw material 3 Solidification target material 4 Holder 5 SR light (synchrotron radiation light) 6 SR device 7 Substrate 8 Material supply pipe (Supply device) 11 Cooler (Coagulation device)

[Procedure amendment]

[Submission date] February 26, 1997

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3

 ────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Takeo Matsubara 1-1-1, Nojihigashi, Kusatsu-shi, Shiga Prefecture Ritsumeikan University Biwako-Kusatsu Campus SR Center

Claims (8)

[Claims] An abrasion is generated by irradiating a synchrotron radiation to a solidified target material obtained by solidifying a gaseous or liquid fluid material containing at least carbon and hydrogen atoms, thereby forming diamond on a substrate. A method for synthesizing diamond, characterized in that it is produced. 2. A laser beam is applied to a solidified target material obtained by solidifying a gaseous or liquid fluid material containing at least carbon and hydrogen atoms, and then a synchrotron radiation is applied to generate ablation. Forming a diamond on the substrate. 3. The diamond synthesis method according to claim 1, wherein the ablation is performed in the presence of a gas containing nitrogen or boron. 4. A reaction chamber, a supply device for supplying a gaseous or liquid fluid material containing at least carbon and hydrogen atoms into the reaction chamber, and a supply device for supplying the supplied gaseous or liquid fluid material. A coagulation device that coagulates to form a coagulation target material, a holding table that holds the coagulation target material in a reaction chamber, a device that irradiates the coagulation target material held by the holding table with synchrotron radiation, A diamond synthesizing apparatus, comprising: a substrate for producing diamond provided in the reaction chamber facing ablation caused by irradiation with synchrotron radiation. 5. A reaction chamber, a supply device for supplying a gaseous or liquid fluid material containing at least carbon and hydrogen atoms into the reaction chamber, and a supply device for supplying the supplied gaseous or liquid fluid material. A coagulation device for coagulating to form a coagulation target material, a holding table for holding the coagulation target material in a reaction chamber, and a device for irradiating the solidification target material held on the holding table with laser light and synchrotron radiation And a substrate for diamond generation provided in the reaction chamber facing ablation caused by the irradiation of the synchrotron radiation. 6. A reaction chamber, a holding table for holding a solidified target material obtained by solidifying a gaseous or liquid fluid material containing at least carbon and hydrogen atoms in the reaction chamber, and a holding table held by the holding table. A device for irradiating the solidified target material with synchrotron radiation, and a substrate for diamond generation provided in the reaction chamber facing ablation caused by the irradiation of the synchrotron radiation. Synthesizer. 7. A reaction chamber, a holding table for holding a solidified target material obtained by solidifying a gaseous or liquid fluid material containing at least carbon and hydrogen atoms in the reaction chamber, and a holding table held by the holding table. A device for irradiating the solidified target material with laser light and synchrotron radiation, and a substrate for diamond generation provided in the reaction chamber opposite to ablation caused by irradiation with the synchrotron radiation. Diamond synthesis equipment. 8. A gas containing nitrogen or boron in the reaction chamber.
8. The diamond synthesizing apparatus according to any one of items 1 to 7.