JP3212372B2 - Selective formation method of diamond film - 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 for selectively forming a diamond film, and more particularly, to a method for selectively forming a diamond film which can be suitably used for a high-performance semiconductor device or an optical waveguide. The present invention relates to a method for selectively forming a diamond film.

[0002]

2. Description of the Related Art In recent years, CVD has been carried out using a mixed gas of a carbon-containing compound and hydrogen as a raw material.
A technique for depositing and forming a diamond film on the surface of a substrate using a vapor phase diamond synthesis technique such as a CVD method or a PVD method has been developed, and its use in fields such as cutting tools and semiconductor devices has attracted attention. In recent years, a technique has been developed to selectively form a fine-patterned diamond film on the surface of a substrate, and not only carbide tools such as cutting tools and polishing tools, but also various sliding members and wear-resistant members. Are expected to be used in a wide range of applications for various materials in the field of electronic and electric devices such as high-performance semiconductor devices.

As a method of selectively forming a diamond film on the surface of a substrate by such a vapor phase method, for example, JP-A-63-303891 discloses a patterning mask made of a metal such as nickel on the surface of a substrate. After that, a method of selectively synthesizing diamond by a gas phase method on a surface to which no metal is applied has been proposed. Also,
JP-A-63-315598 and JP-A-2-1845.
Japanese Patent Publication No. 98 discloses that a pattern is formed by a photoresist film on the surface of a substrate subjected to a scratching process, and that a scratch on a non-mask portion of the substrate is removed by etching. A method for forming a film has been proposed.

However, in these methods, the use of a metal that causes contamination on the surface of the substrate and the use of a strong acid to remove the metal adversely affect the substrate, and furthermore, diamond Since the depth of the flaw caused by the flaw treatment required for the generation of the initial nucleus reaches several thousand angstroms, it takes time for etching, the reproducibility is not sufficient, and it is not possible to perform continuous production etc. in practical use There's a problem. There is a demand for solving the above problems both technically and economically.

[0005] The present invention has been made in view of the above circumstances. An object of the present invention is to provide a method capable of selectively forming a diamond film suitable for a wide range of fields including electronic devices such as high-performance semiconductor devices and optical waveguides without adversely affecting a substrate. Is to do.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, by coating a portion where diamond is desired to be synthesized with a carbon film,
During the scratching process, a scratch that becomes a nucleation point of diamond is introduced only into the carbon film portion, and the selective formation of diamond with high reproducibility is achieved without damaging the non-coated portion of the substrate. In order to complete the present invention, it has been found that the diamond film formed as described above can be suitably used in the field of advanced materials such as electronic device parts requiring high performance and quality such as semiconductor devices and optical waveguides. Reached.

That is, according to the first aspect of the present invention, a pattern is formed on a portion of a substrate surface where a diamond film is formed with a carbon film, and then a pattern is formed on the surface of the carbon film.
Be careful not to scratch the exposed substrate surface
The entire surface of the substrate is scratched with diamond abrasive grains, and then a diamond film is synthesized on the surface of the substrate by a vapor phase method, thereby selectively forming a diamond film on the carbon film forming portion. The invention according to claim 2 is a method for selectively forming a diamond film, wherein the thickness of the carbon film is h and the distance between the patterns is w, and the carbon film has h ≧ w / 2. The method for selectively forming a diamond film according to claim 1, wherein the condition of 1,000 is satisfied and the condition of d> １ ／ w is satisfied with respect to the particle diameter d of the diamond abrasive used in the scratching treatment. is there.

Hereinafter, the present invention will be described in detail.
The method of the present invention includes: 1) a step of forming a pattern film with a carbon film on a portion of the surface of the substrate where a diamond film is to be formed (hereinafter, referred to as a pattern film forming step); 2) scratching the substrate with abrasive grains. 3) a step of forming a diamond film on the surface of the substrate by a vapor phase method (hereinafter, referred to as a diamond film forming step). Hereinafter, the respective steps will be described step by step.

—Pattern Film Forming Step— Various methods can be employed for forming a pattern with the carbon film.

For example, it is possible to form a pattern by a carbon film by coating a carbon film after forming a pattern with a resist, then removing the resist pattern with a solvent and simultaneously removing the carbon film on the surface thereof. it can.

[0011] Alternatively, after a carbon film is first coated on the entire substrate surface, a resist pattern is formed, a metal is further coated, the resist is removed by a solvent, and an ashing process is performed. By etching a portion of the film not masked with the metal and finally dissolving and removing the metal with a strong acid, a pattern of a carbon film can be formed.

In the pattern film forming step, a resist pattern film is first formed on the substrate surface using a resist. More specifically, for example, a coating liquid for forming a pattern film containing a photoresist is applied to the entire surface of the substrate, and dried, and then irradiated with light such as ultraviolet light through a photomask to expose the exposed portion. A resist pattern film is formed by removing or removing the unexposed portion.

As the resist, other than a photoresist, a resist for electron beam or X-ray can be used.
Examples of the photoresist include a negative photoresist and a positive photoresist. As these resists, various known resin-based or rubber-based photoresists can be used in addition to those generally used. Commercially available products include, for example, LMR-33 of Fuji Pharmaceutical Co., Ltd., OMR-83 of Tokyo Ohka Kogyo Co., Ltd.
FPR-800 and the like can be mentioned.

The method for preparing the coating solution for forming a resist pattern film is not particularly limited, and various known methods can be employed. Examples of the method of applying the coating liquid for forming a resist pattern film include a method using a spray, a spinner, a dip, and the like. Among these, a method using a spinner is preferable.

After applying the coating liquid for forming a resist pattern film, it is usually dried to obtain a resist film. Although the dry thickness of the resist film is not particularly limited, it is usually about 0.5 to 3 μm. By irradiating the resist film with light such as ultraviolet rays through a photomask, and developing and rinsing the resist pattern film,
Can be formed.

Examples of the method of exposure by irradiating light such as ultraviolet rays include a contact exposure method, a proximity exposure method, and a projection exposure method. Various methods may be appropriately employed depending on the purpose. Can be selected and used. In this manner, for example, as shown in FIG. 1, the pattern film 2 of the resist is formed on the surface of the substrate 1.

In the carbon film coating, for example, as shown in FIG. 2, a carbon film 3 is formed on the entire surface of the substrate 1 on which the pattern film 2 is formed. Here, examples of the carbon film include a film made of graphite, a polymerized film of carbon, and a film made of diamond-like carbon (DLC).

The method for coating the carbon film is not particularly limited, and examples thereof include a vacuum deposition method using graphite, a PVD method such as an ionization deposition method and a sputtering method, a thermal CVD method, a plasma CVD method and the like. Conventional methods can be suitably used. In particular, a film made of graphite can be formed by a vacuum evaporation method using graphite or the like, and a polymerized carbon film or a DLC film can be formed by employing an RF plasma CVD method or the like.

As the conditions for performing the carbon film coating, various excitation methods, source gases, reaction pressures, reaction temperatures, growth times, and the like can be selected according to the purpose. As the excitation method, DC, AC, RF (13.56M
Hz), microwave (2.45 GHz) or the like.

The raw material may be graphite,
As the source gas, methane, ethane, carbon monoxide and the like are preferable, and particularly preferable are methane, a mixed gas of methane / hydrogen, and a mixed gas of methane / argon. The content of methane in the mixed gas is from 1 to 99 vol. % Is preferred,
Particularly preferred are 10 to 99 vol. %.

The reaction pressure (Pr) is 10 ⁻⁶ to
1,000 Torr is preferable, and particularly preferable is 1 Torr.
0 ^{-4 to} 760 Torr. As the reaction temperature,
77K to 1,200 ° C is preferred, and particularly preferred is
Room temperature to 1,100 ° C.

In the present invention, the thickness of the carbon film formed on the surface of the substrate is determined by the pattern interval. The pattern interval refers to a distance between patterns generated by a carbon film removing step described later (see FIG. 3).

That is, the carbon film thickness h of the carbon film 3 is preferably a value that satisfies h ≧ w / 1,000, where w is the distance between patterns. The value of h is w / 1,00
When it is less than 0, the selectivity decreases.

Next, the resist pattern film and the carbon film on the surface are removed from the surface of the substrate. The removal of the pattern film by the resist is achieved by dissolving and removing the resist using a solvent in which the resist is soluble. Examples of such a solvent include acetone, dimethylformamide, and a 2: 1 mixture of sulfuric acid and hydrogen peroxide. The solvent can be selected according to the type of resist used.

The carbon film does not dissolve in the solvent, but when the solvent is used, the pattern film of the resist easily dissolves in the solvent, and the carbon film formed on the surface of the pattern film simultaneously with the dissolution. Space is created beneath the film and the carbon film becomes very unstable and can be easily removed as a result. On the other hand, the carbon film directly coated on the portion of the surface of the substrate where no pattern film is present is in close contact with the substrate and is not removed even when treated with a solvent. Therefore, as shown in FIG. 3, the carbon film 3 remains in a pattern on the surface of the substrate 1 where the pattern film is not formed.

-Scratching Process Step- In the scratching process step, nucleation points of diamond are introduced on the surface of the substrate. In order to damage the surface of the substrate, it is preferable to use fine particles having relatively high hardness.
iC, cBN, diamond abrasive grains and the like are used.

In the present invention, it is particularly preferable to use diamond abrasive grains having a uniform grain size, for example, having a grain size distribution of ± 50% or less.

An important point in the present invention is that the relationship between the particle diameter d and the pattern interval w of the diamond abrasive grains used in the scratching process is d> １ ／ w, preferably d> １ ／ w, More preferably, those satisfying d> w are used.

By using abrasive grains having such a particle size, the diamond abrasive grains hardly reach the w portion between the patterns where the carbon film remains in a pattern,
The frequency of impact of the abrasive grains is reduced or eliminated.

That is, by using abrasive grains having such a particle size, collision of the abrasive grains with the non-diamond-formed portion on the substrate is eliminated, and the initial diamond nucleus is not formed. I will not do it.

At the time of the scratching treatment, these abrasive grains are used by being dispersed in a solvent. Examples of the solvent include alcohol and acetone. The amount of the abrasive particles dispersed in the solvent is usually 0.05 to 10 g per 100 ml of the solvent, preferably 0.1 to 10 g.
5 g.

In the scratching treatment, the substrate is usually immersed in a solvent solution in which the abrasive grains are dispersed in a solvent, and the solvent solution is irradiated with ultrasonic waves. When the ultrasonic wave is applied, the abrasive grains come into intense contact with the surface of the substrate, thereby causing minute scratches on the surface of the substrate covered with the carbon film. This situation is schematically shown in FIG. In FIG. 4, the surface of the substrate 1 is coated with a carbon film 3, and only the surface of this portion is coated with a carbon film 3.
Fine scratches are made by the scratching process, and nucleation points of diamond are introduced. —Diamond Film Forming Step— The diamond film can be formed by various vapor phase synthesizing methods such as a conventional vapor phase synthesizing method, and among them, a method by a CVD method is suitably adopted. As a CVD method as a vapor phase synthesis method of such a diamond film, for example,
Microwave plasma CVD method, high frequency plasma CVD
Method, hot filament CVD method, DC arc plasma CV
Various methods such as the D method and the magnetic field plasma CVD method (including the ECR method) are known. In the method of the present invention, any of these methods can be applied,
Among them, particularly, a microwave plasma CVD method, a high-frequency plasma CVD method, a hot filament CVD method, a magnetic field plasma CVD method, and the like are suitably applied.

It is known that in such a gas phase synthesis method of a diamond film by a plasma CVD method, various types and compositions of source gases including at least a carbon source gas can be used as a source gas. . As the source gas, for example, a source gas containing a hydrocarbon as a carbon source gas, such as a mixed gas of CH ₄ and H ₂ , and a carbon compound other than a hydrocarbon, such as a mixed gas of CO and H ₂ , may be used. Various source gases such as a source gas contained as a source gas can be given.

In the method of the present invention, as long as a diamond film can be formed, various source gases such as the above-mentioned source gases and the like used in the conventional method can be appropriately used. A diamond film can be formed. Among them, a mixed gas of CO and H ₂ or CH 2
A mixed gas of ₄ and H ₂ is preferred. In particular, when a mixed gas of CO and H ₂ is used as a source gas, the deposition rate of the diamond film is higher than when a hydrocarbon is used, and
It is excellent in that a high-purity diamond can be efficiently formed.

Hereinafter, as a particularly preferred example of the method of forming a diamond film, a preferred example of a method using CO and H ₂ as source gases will be described. That is, in the method of the present invention, the diamond film is formed by using a mixed gas of the following carbon monoxide and hydrogen gas as a source gas (hereinafter, this method is referred to as a method I).
Called. ) Can be particularly suitably performed. That is, the method I is characterized in that a plasma gas obtained by exciting a mixed gas containing carbon monoxide and hydrogen at a rate of 1% by volume or more of carbon monoxide gas is brought into contact with the substrate. And

In the method I, there is no particular limitation on the carbon monoxide to be used. For example, the furnace gas and water gas obtained by hot-reacting coal or coke with air or steam are sufficiently purified. Can be used. There is no particular limitation on the hydrogen to be used, and for example, those obtained by gasification of petroleum, transformation of natural gas, water gas, etc., electrolysis of water, reaction of iron with steam, complete gasification of coal, etc. Can be used.

In this method I, carbon monoxide and the hydrogen are used as raw material gases, and the content of carbon monoxide gas is 1
A gas obtained by exciting the contained gas at a rate of at least 3% by volume, preferably at least 3% by volume, is brought into contact with the substrate to deposit a diamond film on a predetermined surface thereof. If the content of the carbon monoxide gas in the mixed gas is less than 1% by volume, no diamond is produced, or even if diamond is produced, the deposition rate is extremely low.

As a means for exciting the source gas to obtain the source gas containing carbon in an excited state, a conventionally known method such as a plasma CVD method or a hot filament method can be used. When the plasma CVD method is used, the hydrogen forms plasma by irradiation of high frequency or microwave, and when the CVD method such as the hot filament method is used, the hydrogen forms atomic hydrogen by a hot filament. I do. This atomic hydrogen is
It has the function of removing the graphite-structured carbon that is deposited simultaneously with the deposition of diamond.

In this method I, an inert gas can be used as a carrier for the raw material gas. Specific examples of the inert gas include an argon gas, a neon gas, a helium gas, a xenon gas, and a nitrogen gas. These may be used alone or in combination of two or more.

In this method I, the reaction proceeds under the following conditions, and a diamond film is deposited on the surface of the substrate. That is, since the temperature of the surface of the substrate varies depending on the means for exciting the source gas, it cannot be unconditionally determined. Room temperature to 1,
100 ° C. If this temperature is lower than room temperature, the deposition rate of the diamond film may be slow, or excited carbon may not be generated. On the other hand, if the temperature is higher than 1,200 ° C., the diamond film deposited on the surface of the substrate may be etched away and the deposition rate may not be improved.

The reaction pressure is usually 10 ⁻³ to 10 ³ t.
orr, preferably 1 to 800 Torr. If the reaction pressure is lower than 10 ^-3 Torr, the deposition rate of the diamond film will be slow, or the diamond film will not be deposited. On the other hand, even if the pressure is higher than 10 ³ Torr, the corresponding effect cannot be obtained.

As described above, in the present invention, a diamond film can be selectively formed on the carbon film pattern forming portion on the surface of the substrate. In the method of the present invention, the diamond film may be formed by applying a method other than the method I described above. The thickness of the diamond film to be formed may be appropriately determined depending on the purpose of use and the like, and is not particularly limited in this sense, but is usually selected in a range of 1 to 100 μm. Good.

If the film thickness is too small, diamond may not be obtained as a film. On the other hand, if the film thickness is too large, the diamond film may peel off depending on the use conditions. In addition, when using the obtained diamond under severe conditions such as a cutting tool, it is usually preferable to select this thickness in the range of 5 to 100 μm.

According to the method of the present invention, a place where diamond is to be synthesized is coated with a carbon film, so that a scratch which becomes a nucleation point of diamond is introduced only in the carbon film portion during the scratching treatment, and non-coating is performed. It is possible to selectively form a diamond film with high reproducibility efficiently without damaging the substrate of the coating portion, and to reduce damage to the non-coated portion of the diamond on the substrate.
Contamination other than carbon components on the substrate surface can be reduced.

[0045]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples of the present invention and Comparative Examples thereof, but the present invention is not limited to these Examples. (Example 1) -Pattern film forming process- A resist pattern film forming coating liquid composed of a negative photoresist (manufactured by Fuji Pharmaceutical Co., Ltd .: LMR-33) was applied to the surface of a Si wafer substrate at a rate of 3 / min. 2,000rpm
To form a resist layer on the surface of the substrate. After coating, the coating film was heated at 60 ° C. for 30 minutes. Next, as shown in FIG.
A photomask 6 in which exposure windows 5 each having a square of μm are arranged in a matrix at intervals of 5 μm is arranged on a resist layer on a substrate, and is irradiated with a Xe-Hg lamp (a wavelength of 300 nm or less). It was exposed (30 mJ / cm ² ). After exposure, the film was heated at 100 ° C. for 30 minutes.
After removing at 80 ° C. for 80 seconds, rinsing was performed at 20 ° C. for 20 seconds with an LMR rinse solution manufactured by the company to form a resist pattern film.

Next, RF parallel plate type plasma CVD
Oxygen supply 10sccm, pressure 0.1To using the device
Ashing was performed at rr and RF output of 200 W for 15 seconds to completely remove the resist, and then a carbon film was formed under the following conditions.

Kind of introduced raw material gas and its flow rate: CH
₄ , 50 sccm, system pressure: 0.1 Torr, RF output: 150 W, reaction time: 30 minutes As a result, a carbon film having a thickness of about 2,000 mm was coated on the surface of the substrate.

Further, the substrate was washed with dimethylformamide to dissolve and remove the resist pattern film on the substrate surface, and at the same time remove the carbon film formed on the surface of the resist pattern film.

—Scratching Step— In an ultrasonic cleaning apparatus, 0.5 g of diamond powder having a particle size of 5 to 12 μm is dispersed in 100 ml of acetone, the substrate is immersed in the liquid, and the scratching is performed for 15 minutes. Done.

—Diamond Film Forming Step— A diamond film was formed under the following conditions. Source gas type and flow rate: mixed gas of CO and H ₂ , 10
/ 90 sccm Synthesis conditions: reaction pressure 40 Torr, substrate temperature 900 ° C.
Synthesis time 2 hours Synthesis method (source gas excitation method): microwave plasma CVD
Method (2.45 GHz). As a result, formation of a diamond film was observed in the portion where the carbon film was formed.

[0051]

According to the present invention, it is possible to selectively form a diamond film suitable for a wide range of fields including electronic devices such as high-performance semiconductor devices and optical waveguides without adversely affecting the substrate. Thus, it is possible to provide a method for producing a diamond film that is extremely useful in practice.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a surface of a substrate having a pattern film formed on the surface.

FIG. 2 is a diagram showing a pattern film formed on a surface of a substrate;
It is sectional drawing which shows the state in which the carbon film was formed.

FIG. 3 is a cross-sectional view showing a state in which a pattern film is removed and a carbon film is left on the surface of a substrate.

FIG. 4 is a cross-sectional view showing the substrate and diamond abrasive grains for the scratching process in the scratching process on the surface of the substrate shown in FIG. 3;

FIG. 5 is a plan view showing a photomask.

[Description of sign]

 DESCRIPTION OF SYMBOLS 1 Base material 2 Pattern film 3 Carbon film 4 Abrasive grains 5 Exposure window 6 Photomask h Carbon film thickness w Distance between patterns d Particle size of diamond abrasive grains

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-241898 (JP, A) JP-A-3-112898 (JP, A) JP-A-2-225398 (JP, A) JP-A 62-21898 108799 (JP, A) JP-A-63-315598 (JP, A) JP-A-2-184598 (JP, A) JP-A-62-226889 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C30B 1/00-35/00 CA (STN) JICST file (JOIS)

Claims (2)

(57) [Claims] After forming a pattern with a carbon film on a portion of a substrate surface where a diamond film is formed , the surface of the carbon film is scratched.
To avoid scratching the exposed board surface.
A diamond film is selectively formed on the carbon film forming portion by subjecting the entire surface of the substrate to a scratching process with a Monde abrasive , and then synthesizing a diamond film on the surface of the substrate by a vapor phase method. Method for selectively forming a diamond film. 2. When the thickness of the carbon film is h and the distance between patterns is w, the thickness of the carbon film is h ≧ w / 1,00.
2. The method for selectively forming a diamond film according to claim 1, wherein the condition of 0 is satisfied and the condition of d> １ ／ w is satisfied with respect to the particle diameter d of the diamond abrasive used for the scratching treatment.