JP3238545B2 - Method for forming initial diamond nucleus and method for producing diamond thin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming an initial diamond nucleus and a method for producing a diamond thin film.
More specifically, the present invention relates to a method for forming a diamond initial nucleus and a method for producing a diamond thin film, which can easily and simply produce diamond suitable for a constituent material of a high-performance electronic device and the like with good reproducibility. .

[0002]

2. Description of the Related Art Recently, application and research of diamond thin films to electronic devices has been actively conducted. When a diamond thin film is applied to integration of various devices or wiring between devices, a technique for selectively forming a diamond thin film having a desired shape is required. Conventionally, as such a technique, several methods for selectively forming diamond have been proposed. However, in these conventional methods,
Since the manufacturing process is complicated and the selectivity is not high, there is a problem that it is difficult to easily and reproducibly produce a diamond thin film having a desired shape.

In order to solve such a problem, Japanese Patent Laid-Open Publication No.
No. 15598 proposes a method in which a surface of a substrate is scratched, a predetermined mask is formed, etching is performed by an argon ion beam, the mask is removed, and a diamond thin film is formed by a vapor phase method. Have been. However, in the case of this method, in order to improve the selectivity, it is necessary to strengthen the etching treatment, and as a result, the substrate is damaged, and a diamond having a desired shape cannot be easily manufactured. There is. On the other hand, a method of chemically etching a substrate and a method of forming a pattern using an iron thin film on a substrate have been proposed. In these methods, however, the steps are still complicated, and the selectivity cannot be improved. The problem has not been solved.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and can easily and simply produce a diamond thin film suitable for high-performance semiconductor devices and optical waveguides into a desired shape with good reproducibility. An object is to provide a method for forming a nucleus and a method for manufacturing a diamond thin film.

[0005]

According to the first aspect of the present invention, a carbon-containing thin film is formed on a surface of a substrate, and then the carbon-containing thin film is treated with an ion beam (hydrogen ion beam). The method according to claim 2, wherein the ion beam processing is drawing by an ion beam. The invention according to claim 3 is a method for forming an initial diamond nucleus, wherein a carbon-containing thin film is formed on a surface of a substrate, and the carbon-containing thin film is subjected to ion beam treatment (excluding hydrogen ion beam treatment).
Good. ) , And then forming a diamond thin film on the surface of the substrate by a vapor phase method.

Hereinafter, a method for forming an initial diamond nucleus and a method for manufacturing a diamond thin film according to the present invention will be described in detail.

The method for forming an initial diamond nucleus according to the present invention includes the following steps: 1) a step of forming a carbon-containing thin film on the surface of a substrate (hereinafter referred to as a carbon-containing thin film forming step); Performing a process using a beam (hereinafter, referred to as an ion beam processing step). Further, the method for producing a diamond thin film according to the present invention includes, in addition to the above 1) and 2), 3) a step of forming a diamond thin film on the surface of the substrate by a vapor phase method (hereinafter referred to as a diamond thin film forming step). ).
Hereinafter, the respective steps will be described in order.

1) Step of forming a carbon-containing thin film In this step of forming a carbon-containing thin film, a carbon-containing thin film is formed on the surface of a substrate.

-Substrate-The substrate is not particularly limited as long as it is a material capable of forming a carbide. For example, Si, gallium-arsenic, SiO
₂ , ceramics, sapphire, cemented carbide and the like. The substrate may be a P-type or N-type semiconductor. In the present invention, among these,
These single crystal substrates are preferable, and particularly, a Si single crystal substrate is preferable. The specific resistance of the substrate is usually 10 ^-6 to 1
0 ³ Ω · cm. The size, shape, and the like of the substrate can be appropriately selected.

-Carbon-Containing Thin Film- The carbon-containing thin film is not particularly limited as long as it is a carbon-containing thin film. For example, diamond-like carbon (hereinafter referred to as DLC), amorphous carbon, graphite, etc. Can be mentioned.

The method for forming the carbon-containing thin film is not particularly limited. For example, PVD method, RF plasma C
VD method, ECR plasma CVD method, ionization evaporation method, ion plating method, sputtering method, plasma C
Conventional methods such as the VD method can be used. Among these, RF plasma CVD, ionization vapor deposition, sputtering, and plasma CVD are preferred. Further, the slurry of graphite powder may be applied to the substrate by various application methods.

As the conditions for forming the carbon-containing thin film, various excitation methods, source gases, reaction pressures, reaction temperatures, growth times, and the like can be appropriately selected depending on the purpose.

As the excitation method, DC, AC, RF
(13.56 MHz), microwave (2.45 GHz)
And the like. Of these, RF is preferred.

The raw material gas includes methane, ethane,
Carbon monoxide and the like are preferable, and methane, a mixed gas of methane / hydrogen, and a mixed gas with a rare gas such as methane / argon are particularly preferable. The content of methane in the mixed gas is 1 to 1
00 vol. % Is preferred, especially 10 to 100 vol.
% Is preferred.

The reaction pressure (Pr) cannot be specified unconditionally because it differs depending on the synthesis method.
In the plasma method, 10 ^{-6 to} 10 Torr is preferable, and 10 ^{-4 to 1} Torr is particularly preferable.

The reaction temperature is 77K to 1100
C is preferable, and room temperature to 500C is particularly preferable.

The thickness of the carbon-containing thin film is usually 5
0 ° to 10 μm, preferably 500 ° to 1 μm.
If the thickness is less than 50 °, it may not be possible to sufficiently form a carbide thin film such as SiC in the subsequent ion beam treatment. On the other hand, if it exceeds 10 μm, it takes time to form a carbide thin film such as SiC, which may be inefficient.

As described above, the carbon-containing thin film 3 can be formed on the surface of the substrate 1 as shown in FIG.

2) Ion beam treatment step In this ion beam treatment step, the carbon-containing thin film formed on the surface of the substrate is treated with an ion beam to form a carbide thin film pattern on part or all of the carbon-containing thin film.

-Treatment with Ion Beam-The treatment with the ion beam can be performed by irradiating the carbon-containing thin film with the ion beam under predetermined conditions using a known ion beam apparatus.

As the ion beam device, a focused ion beam device can be preferably exemplified.

As the ion source of the ion beam, for example, Ga ⁺ , Ar ⁺ , Be ⁺ , Ge ⁺ , As ⁺ , Sb
⁺ , Au ⁺ , B ⁺ , Si ^{+ and the} like. Among these, Ga ⁺ is preferable.

The conditions include the acceleration energy of the ion beam, the irradiation dose, and the like.

The acceleration energy of the ion beam is usually 1 to 200 keV, and 10 to 150 keV.
Is preferred, and particularly preferably 40 to 100 keV. When the acceleration energy is less than 1 keV, the generation density of diamond initial nuclei may decrease. On the other hand, 20
Even when it exceeds 0 keV, the generation density of diamond initial nuclei may decrease.

The dose of the ion beam is usually 10 ¹¹ to 10 ¹⁸ / cm ² , and 10 ¹² to 10 ¹⁷ / cm 2
² is preferred, and particularly preferably 10 ¹⁵ to 10 ¹⁶ / cm ² . If the irradiation amount is less than 10 ¹¹ / cm ² , the generation density of diamond initial nuclei may decrease. On the other hand, even if it exceeds 10 ¹⁸ / cm ² , the effect corresponding thereto is not seen.

By subjecting the carbon-containing thin film on the substrate surface to the ion beam treatment, the initial diamond nucleus generation density becomes 10 ⁷ to 10 ¹⁰ / cm ² .

Note that conditions other than these, for example, pressure, temperature, time, atmosphere, etc., can be appropriately selected.

The irradiation may be performed on the entire surface of the carbon-containing thin film or on a part of the carbon-containing thin film. In the present invention, the irradiation is performed on a desired portion, that is, the irradiation is drawing. Is preferred. For example, as shown in FIG. 2, the carbon-containing thin film 3 formed on the surface of the substrate 1
Drawing may be performed by irradiating an ion beam such as ⁺ in a line shape.

For the drawing, various drawing methods can be used. Examples of the drawing method include a serpentine drawing method, a basket wave drawing method, a continuously moving table drawing method, and a step-and-repeat drawing method. Can be.

-Carbide thin film pattern-When the treatment with the ion beam is performed, part or all of the carbon-containing thin film is changed into a carbide thin film. At this time, if the drawing is performed in a desired shape, a carbide thin film pattern having a desired shape can be formed. For example, as shown in FIG. 2, when the ion beam is irradiated linearly, a linear carbide thin film pattern 4 as shown in FIG. 1 can be formed.

The carbide thin film is a carbide of an element of the substrate and carbon contained in the carbon-containing thin film. For example, when silicon is used for the substrate, the carbide thin film is
SiC. The formation of the carbide causes part or all of the carbon contained in the carbon-containing thin film to form a compound.

3) Diamond Thin Film Forming Step In this diamond thin film forming step, a diamond thin film is heteroepitaxially formed on the carbide thin film pattern formed on the surface of the substrate.

-Diamond thin film- As a method of heteroepitaxially forming the diamond thin film, various diamond vapor phase synthesis methods known per se can be used. Specifically, CV
Examples include D method, PVD method, PCVD method, or a combination thereof. Among them, usually EA
Preferable examples include various hot filament methods including the CVD method, various DC plasma CVD methods including the thermal plasma method, and microwave plasma CVD methods including the thermal plasma method.

Examples of the carbon source gas used in the method for forming the diamond thin film include paraffinic hydrocarbons such as methane, ethane, propane and butane; olefinic hydrocarbons such as ethylene, propylene and butylene; and acetylene such as acetylene and allylene. -Based hydrocarbon; butadiene,
Diolefin hydrocarbons such as allene; cyclopropane,
Alicyclic hydrocarbons such as cyclobutane, cyclopentane and cyclohexane; aromatic hydrocarbons such as cyclobutadiene, benzene, toluene, xylene and naphthalene; ketones such as acetone, diethyl ketone and benzophenone; alcohols such as methanol and ethanol; Other oxygen-containing hydrocarbons; amines such as trimethylamine and triethylamine; other nitrogen-containing hydrocarbons; carbon dioxide, carbon monoxide, carbon oxide and the like. Among them, methane, ethane, paraffinic hydrocarbons such as propane, ethanol, alcohols such as methanol, acetone, ketones such as benzophenone, trimethylamine, amines such as triethylamine, carbon dioxide, and carbon monoxide are particularly preferable. Carbon monoxide is preferred. These may be used alone or in combination of two or more as a mixed gas. These may be mixed with an active gas such as hydrogen or an inert gas such as helium, argon, neon, xenon, or nitrogen.

The conditions for forming the diamond thin film include a reaction pressure, a reaction temperature, and a reaction time.

The reaction pressure is usually from 10 ^-6 to 10
³ Torr, preferably 1 to 760 Torr. When the reaction pressure is less than 10 ^-6 Torr, the formation rate of the diamond thin film may be reduced. Meanwhile, 1
If the pressure exceeds 0 ³ Torr, no further effect may be obtained compared to the effect obtained at 10 ³ Torr.

The reaction temperature can be based on the surface temperature of the substrate. Since the surface temperature of the substrate depends on the activation means of the carbon source gas and the like,
Although it cannot be specified unconditionally, it is usually between room temperature and 1,2
00 ° C, preferably room temperature to 1,100 ° C. If the surface temperature of the substrate is lower than room temperature, formation of a diamond thin film may not be sufficient. On the other hand, when the temperature exceeds 1,200 ° C., etching may occur in the formed diamond thin film.

The reaction time is not particularly limited.
The thickness can be appropriately selected according to the diamond thin film forming speed so that the diamond thin film has a desired thickness.

The thickness of the diamond thin film may be appropriately selected according to the purpose of use and the like, and is not particularly limited in this sense, but is usually 1 to 100 μm.

As described above, as shown in FIG. 1, a diamond thin film 2 having a desired shape and size is selectively heteroepitaxially formed with good dimensional accuracy only on a carbide thin film pattern 4 formed on the surface of a substrate 1. be able to.

According to the method for forming an initial diamond nucleus of the present invention, an initial nucleus of a fine carbide thin film pattern can be easily formed by a simple operation. Further, according to the method for forming a diamond thin film of the present invention, a diamond thin film having an arbitrary shape can be easily and simply manufactured, and selectively and with good reproducibility. The obtained diamond thin film can be suitably used in various fields including various electronic materials such as constituent materials of electronic devices.

[0042]

【Example】

(Example 1) 1) Step of forming carbon-containing thin film-substrate-As the substrate, a P ⁺ (100) Si substrate was used.

-Carbon-Containing Thin Film- On the surface of the substrate, an RF plasma CVD method is used.
1 Torr, room temperature, 20 minutes, 50 sccm C
By reacting H ₄ , DLC with a thickness of 2000 mm
A thin film was formed.

2) Ion beam treatment step—Ion beam treatment— Using a focused ion beam apparatus, the ion source of the ion beam was Ga ⁺ , the acceleration energy was 50 keV, and the irradiation amount was 10 ¹⁵ / cm ^2. Then, an ion beam was drawn on the DLC thin film in a line at 0.5 mm intervals.

-Carbide thin film pattern- As a result of the treatment with the ion beam, a part of the DLC reacts with Si of the substrate to form SiC, and a pattern of linear SiC and DLC at 0.5 mm intervals is formed.

At this time, the initial diamond nuclei could be formed at a high density of 7.5 × 10 ⁸ / cm ² .

3) Diamond thin film forming step The surface of the substrate having undergone the above-mentioned ion beam processing step is subjected to microwave plasma CVD at 40 Torr and 900 Torr.
CO / H ₂ = 10/90 sccm for 1 hour under the condition of
Was reacted to form a diamond thin film.

As a result, a diamond thin film was selectively formed on the pattern made of SiC, and a linear diamond thin film having a width of 0.5 mm could be manufactured.
In this case, the selectivity was as high as 2 × 10 ⁴ .

(Comparative Example 1) A diamond thin film was manufactured in the same manner as in Example 1 except that the ion beam treatment step was not performed.

As a result, only diamond grains were formed at a density of 10 ⁴ / cm ^{2 on} the surface of the substrate.

[0051]

According to the present invention, it is possible to easily and simply produce a diamond thin film suitable for high-performance semiconductor devices and optical waveguides into a desired shape with good reproducibility. A method and a method for producing a diamond thin film can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a state in which a diamond thin film is selectively formed on a surface of a substrate.

FIG. 2 is a schematic cross-sectional explanatory view showing a state in which a carbon-containing thin film formed on a surface of a substrate is irradiated with an ion beam.

FIG. 3 is a schematic sectional view showing a state in which a carbon-containing thin film is formed on a surface of a substrate.

[Description of Symbols] 1 ... substrate, 2 ... diamond, 3 ... carbon-containing thin film, 4 ... carbide thin film pattern,

Claims (3)

(57) [Claims] After forming a carbon-containing thin film on a surface of a substrate, the carbon-containing thin film is subjected to an ion beam treatment (hydrogen ion
Excludes beam processing. A) forming a diamond initial nucleus. 2. The method for forming an initial diamond nucleus according to claim 1, wherein said ion beam processing is drawing by an ion beam. 3. A carbon-containing thin film is formed on a surface of a substrate, and the carbon-containing thin film is subjected to an ion beam treatment (hydrogen ion beam).
Excluding processing. ) , And then forming a diamond thin film on the surface of the substrate by a gas phase method.