JP3241447B2 - Selective diamond formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method for selectively forming diamond, and more particularly to a method for forming a diamond having a desired pattern on a substrate without performing a scratching process as an initial nucleation process of diamond.

The method for selectively forming diamond according to the present invention can be suitably used in various fields relating to diamond film pattern formation, such as, for example, the manufacture of electronic materials such as semiconductor elements, and micromachining.

[0003]

2. Description of the Related Art In recent years, a technique for forming a diamond film on a substrate by a vapor phase synthesis method has been developed, and the resulting diamond film material has been applied to various uses. I have. Diamond films are excellent in mechanical strength such as surface hardness, so they are useful for tools such as cutting tools and polishing tools.In addition, they have high dielectric strength and thermal conductivity, and have excellent semiconductor properties due to doping. Therefore, it is expected to be used for various electronic materials such as semiconductor elements.

In the field of precision processing of electronic materials and the like, a micro-processing technique called patterning is often used. Even when a diamond film is used as an electronic material or the like, it is often necessary to form a fine pattern of the diamond film on a substrate.

As a method of forming a diamond film having a pattern of a predetermined shape, for example, a method of forming a pattern by etching (see JP-A-63-34927) and a method of masking (see JP-A-62-2973)
No. 98) and a method of combining a masking method and a method of applying a positive bias voltage (Japanese Patent Laid-Open No.
No. 115194). However, it is very difficult to etch the diamond curtain once formed on the substrate, and there is a problem that not only a special etching device is required but also a special etching operation is required. Further, in the case of a mechanical scratching process in which a substrate is scratched with diamond abrasive grains or the like, pattern reproducibility is not sufficient. Furthermore, a method of combining a masking method and a method of applying a positive bias voltage cannot realize a sufficient pattern formation.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to improve the above situation. An object of the present invention is to increase the density of diamond initial nuclei in a predetermined region where a diamond film is to be formed on a substrate when forming a diamond film on a substrate in a predetermined pattern, and to form a diamond film in a region where a diamond film is not formed. It is an object of the present invention to provide a method for forming a diamond film selectively by forming a mask pattern to suppress generation of initial diamond nuclei.

[0007]

According to a first aspect of the present invention, there is provided a method for forming a pattern on a substrate using a masking material, followed by an electric field plasma treatment (hydrogen plasma treatment).
Excluding processing. ), And then performing a hydrogen plasma treatment to synthesize diamond by a vapor phase method. The invention according to claim 2, wherein the masking material is used. Is a method for selectively forming diamond according to claim 1, wherein the masking material is an electrically insulating masking material. The invention according to claim 3, wherein the masking material is removed after the diamond is synthesized. The method according to claim 4, wherein the electrically insulating masking material is silica,
It is a method for selectively forming diamond according to claim 2, which is at least one selected from silicon nitride and silicon carbide, and the method according to claim 5, wherein after forming a pattern on a substrate with a masking material, This is a method for selectively forming diamond, characterized in that plasma processing comprising a combination of electric field plasma processing and hydrogen plasma processing is performed on a substrate, a masking material is removed, and then diamond synthesis is performed by a gas phase method.

Hereinafter, the method of the present invention will be described in detail.
The method of the present invention includes (1) a step of forming a pattern on a substrate with a masking material (may be abbreviated as a pattern forming step), and (2) a step of performing an electric field plasma treatment after the above step (an electric field plasma treatment step). (3) a step of removing the masking material (sometimes abbreviated as a masking removing step), and (4) a step of synthesizing diamond by a vapor phase method (a diamond synthesizing step). May be abbreviated).

In the method of the present invention, the step (3) may be performed after the step of performing the electric field plasma treatment, and then the step (4) may be performed after that. After the above, the step (4) is performed,
Thereafter, the step (3) may be performed. In some cases, the step (3) can be omitted.

Hereinafter, each of the above steps will be described. (1) Pattern Forming Step In the method of the present invention, the material of the substrate is not particularly limited, and is used for forming a diamond film by a known vapor phase synthesis method (for example, various metals, alloys, Cemented carbides, semiconductors, etc.) and various types can be appropriately selected and used. Some specific examples will be described. For example, WC-based cemented carbide such as WC-Co-based, Ti
N, Si ₃ N _{4 and} other nitride ceramics, SiC, T
Examples include oxides such as carbide-based ceramics such as iC, semimetals and semiconductors such as silicon, and a variety of things such as those obtained by oxidizing the substrate surface.

For example, when a substrate with a diamond film obtained by the method of the present invention is used as a semiconductor material, silicon, germanium,
Examples thereof include silicon carbide, boron nitride, and gallium / arsenic. Of course, these may have electrical characteristics such as semiconductor characteristics controlled in advance by doping or the like, or may be processed into an arbitrary shape and configuration.

In this pattern forming step, a mask layer for exposing a region to be subjected to the electric field plasma treatment and masking the other region is formed, and a pattern using the mask layer is formed. Accordingly, wood charge of the mask layer for masking a region other than the region to be the electric field plasma treatment as is (hereinafter sometimes referred to as masking material.), Using a substrate with different materials. This is because the effect of the electric field effect differs depending on the material, and as a result, pattern formation becomes impossible. For example, when silicon carbide is used for the substrate, tungsten, molybdenum, titanium, or the like can be suitably used as the masking material.

When an insulating material is used as the masking material, the portion covered with the electrically insulating masking material is not affected by the electric field plasma, and a nucleation point for diamond generation is not introduced. A clear pattern can be formed. Examples of such an insulating material include carbides, oxides, and nitrides of transition metals, among which SiO ₂ , Si ₃ N _4, and SiC are preferred examples.

In this pattern forming step, in order to mask a region other than a region to be subjected to the electric field plasma treatment,
For example, the entire surface of the substrate is covered with the masking material, then a pattern film is formed with a resist or the like, and thereafter, a part of the masking material not covered with the pattern film is removed, and the pattern film is further removed. A first method of forming a mask layer by forming a pattern film with a resist or the like on the surface of the substrate, and then forming a masking material on the entire surface, and further removing the pattern film to form a mask. A second method of forming a layer (lift-off method) can be employed. Further, a third method is employed in which the surface of the substrate is covered with a patterned mask plate, and then the masking material is formed by vapor deposition or the like, and the mask plate is removed to form a mask layer of the masking material. be able to.

In both the first and second methods, the thickness of the mask layer is usually 1 mm to 500 °.
And preferably in the range of 500 μm to 1,000 °.
To form a mask layer on the entire surface of the substrate in the first method or the second method, or to form a mask layer on the surface of the substrate in the third method, there is no particular limitation, generally A typical thin film forming method is applicable. Specific examples include a CVD method, a sputtering film forming method, an evaporation method using resistance heating, an electron beam evaporation method, an ion plating method, and various evaporation methods.
Further, Si is used as a substrate, and SiO _{2 is} used as a masking material.
When using a method, a method of thermally oxidizing a Si substrate under predetermined conditions may be used. The method and conditions for forming the thin film may be appropriately selected depending on the material of the mask layer.

In the first method or the second method, the pattern film formed on the surface of the substrate may be formed, for example, by applying a coating liquid for forming a pattern film containing a photoresist over the entire surface of the mask layer on the substrate. It can be formed by drying and then irradiating light such as ultraviolet light through a photomask to remove exposed portions or unexposed portions. In addition, as the resist, a resist for an electron beam or an X-ray can be used in addition to a photoresist.

The photoresist may be a negative photoresist or 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. and OM of Tokyo Ohka Kogyo Co., Ltd.
R-83, OFPR-800 and the like.

The method for preparing the coating liquid for forming a 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 pattern film include a method using a spray, a spinner, a dip, and the like, and among them, a method using a spinner is preferable. After applying the coating liquid for forming a pattern film, the photoresist film is dried in a usual case to obtain a photoresist film.

Then, the pattern film can be formed by irradiating the photoresist film with light such as ultraviolet rays through a photomask, and developing and rinsing the photoresist film. Examples of the method of exposure by irradiating light such as the ultraviolet light include, for example, a contact exposure method, a proximity exposure method, a projection exposure method, and the like, and various methods are appropriately selected depending on the purpose. Can be used.

In the first method, the pattern film formed on the surface of the substrate may be formed by directly applying a commercially available resin, grease, or wax to a region other than a region to be subjected to the electric field plasma treatment. Can also. Regardless of the method, the dry thickness of the pattern film is
Although there is no particular limitation, it is usually 0.1 to 500 μm, preferably 0.5 to 100 μm.

Next, a part of the mask layer not covered with the pattern film is removed by etching. In this etching, the masking material for forming the mask layer is S
When it is iO _2, it is preferable to employ wet etching with an HF aqueous solution or dry etching with reactive ion etching using RF plasma. After removing a part of the mask layer, the pattern film is preferably removed by washing with a solvent that dissolves the resist.

(2) Electric Field Plasma Treatment Step In the method of the present invention, after the above-described pattern formation step, electric field plasma treatment is performed on a portion of the substrate that is not covered by the mask layer, that is, on the exposed surface of the substrate.
This electric field plasma treatment can be performed by applying plasma of a carbon-containing compound or plasma of a mixed gas of a carbon-containing compound and hydrogen to the substrate while applying a negative bias voltage to the substrate. As the gas used for the electric field plasma treatment, a carbon-containing compound gas, or a gas mixture containing a carbon-containing compound and hydrogen, which is commonly used as a general diamond synthesis gas,
Alternatively, a usable one can be used.

Examples of the carbon-containing compound include various hydrocarbons (specifically, alkanes such as methane, ethane, propane, butane, pentane and hexane; alkenes such as ethylene, propylene, butene and pentene;
Various kinds of hydrocarbons such as aromatic hydrocarbons such as benzene and toluene, cycloalkanes such as cyclopentane and cyclohexane), oxygen-containing hydrocarbons (specifically, for example, methanol, ethanol, propanol, ethylene glycol, Alcohols such as benzyl alcohol,
Ketones such as acetone, methyl ethyl ketone, cyclohexanone and acetophenone; carboxylic acids such as acetic acid and propionic acid; and various kinds of oxygen-containing hydrocarbons such as ethers such as dimethyl ether, diethyl ether and tetrahydrofuran), various carbons such as CO and CO ₂ Compounds may be included. Among these, particularly preferred are, for example, methane, methanol,
Acetone, CO and the like can be exemplified. These may be used alone or in a combination of two or more.

When a mixed gas of the carbon-containing compound and hydrogen is used, the content of the carbon-containing compound is 0.05 to 99% by volume, preferably 0.1 to 80% by volume, particularly preferably 3 to 80% by volume based on the whole mixed gas. It is desirable that the ratio is a percentage by volume. When the ratio of the carbon-containing compound in the mixed gas is in the above range, the density of initial diamond nuclei on the substrate surface can be significantly increased, which is preferable.

The method of the plasma treatment for converting the carbon-containing compound or the mixed gas of the carbon-containing compound and hydrogen into plasma is not particularly limited, and is used for general diamond or a vapor phase synthesis method of a diamond film. Various plasma processing methods such as a plasma method can be applied. Specifically, for example, microwave plasma method, high-frequency plasma method, hot filament method, ECR
Method, DC arc method using arc discharge plasma, AC
Examples of the method include an arc method, an RF arc method, and a combination method thereof. Among these,
A plasma processing method using a microwave plasma method is preferably employed.

The reaction conditions for the plasma treatment can be the same as those in the past. Specifically, for example, the pressure of the reaction system is in the range of 10 ^-3 to 10 ³ Torr, preferably 0.1 to ³ Torr. 760 Torr, the substrate temperature is in the range from room temperature to 1,200 ° C., preferably from room temperature to 1,100 ° C.
It can be suitably performed by selecting the temperature in the range of ° C.

The negative bias voltage applied to the substrate is, for example, a DC bias in a range of -500 to -5V, preferably in a range of -400 to -20V. In addition, a method of applying RF alone or an RF + DC bias so that the bias voltage is in the range of −500 to −5 V is also preferably adopted. The time for the electric field plasma treatment is usually 1 second to 30 minutes.

In the method of the present invention, (3) a masking removing step and (4) a diamond synthesizing step, which will be described in detail later, are performed after the electric field plasma processing. Is preferably followed by a hydrogen plasma treatment. Further, this processing can be alternately repeated at least twice or more.

Although there is no particular limitation on the hydrogen gas used in the hydrogen plasma treatment, a hydrogen gas purified to a high purity is usually used. When hydrogen gas is used in the above-described electric field plasma processing, the hydrogen gas can be used continuously.

The method of plasma treatment for converting hydrogen gas into plasma is not particularly limited, and a plasma treatment method by various methods such as a plasma treatment method used for a general vapor phase synthesis method of diamond or a diamond film is used. Applicable. Specifically, for example, microwave plasma method, high-frequency plasma method, hot filament method, ECR
Method, an arc discharge plasma method, or a combination thereof. Among these, a plasma processing method using a microwave plasma method is particularly preferably employed. The reaction conditions for the hydrogen plasma treatment are almost the same as the conditions for the electric field plasma treatment. The time for the hydrogen plasma treatment is usually 1 second to 30 seconds.
Minutes.

In the method of the present invention, the above-described electric field plasma treatment and hydrogen plasma treatment are preferably alternately repeated at least twice. As a preferred embodiment of alternately repeating the two types of plasma treatment, for example, hydrogen gas is continuously passed through the reaction system, and the carbon-containing compound is intermittently passed through the reaction system at a constant flow rate at a constant flow rate. And applying a negative bias to the substrate in the reaction system in synchronization with the flow of the carbon-containing compound. In this embodiment, the distribution of the carbon-containing compound is turned on.
/ OFF, ON / OF of the negative bias voltage for the substrate
Since only F needs to be controlled, the operation is simple.

In the method of the present invention, when the above-described electric field plasma treatment and hydrogen plasma treatment are alternately repeated at least twice, the generation density of diamond initial nuclei is further increased, the number of impurities is small, and the crystallinity is good. Diamond can be manufactured with good adhesion to the substrate. As described above, by subjecting the substrate to the electric field plasma treatment or alternately repeating the electric field plasma treatment and the hydrogen plasma treatment at least twice or more, the diamond initial nuclei are efficiently and densely generated on the substrate. Can be.

(3) Masking Removal Step In the method of the present invention, after the electric field plasma treatment, the electric field plasma treatment and the hydrogen plasma treatment are optionally repeated at least twice or more, if necessary.
The mask layer is removed. However, after the electric field plasma processing, the electric field plasma processing and the hydrogen plasma processing are alternately repeated at least two times or more, and then a diamond synthesizing step described in detail later is executed. The steps may be performed.

Further, since the mask material of the mask layer is etched in the diamond synthetic plasma, the masking removing step may be omitted in some cases. To remove the mask layer, either a wet etching method or a dry etching method can be employed.

As the wet etching method, for example, when the mask layer is formed of SiO ₂ , a method of treating with a HF aqueous solution can be used. When the substrate with the mask layer is washed with an HF aqueous solution, SiO ₂ can be effectively removed.

On the other hand, as the dry etching method, a method such as a commonly used plasma method can be employed. The mask layer may be completely removed, but in some cases, the mask layer may be partially removed.

(4) Diamond Synthesis Step In the method of the present invention, after performing the above pretreatment, diamond is formed on the substrate by a gas phase synthesis method using a carbon source gas. Examples of the carbon source gas include paraffinic hydrocarbons such as methane, ethane, propane and butane; olefinic hydrocarbons such as ethylene, propylene and butylene; acetylenic hydrocarbons such as acetylene and allylene; butadiene and allene Diolefinic hydrocarbons; alicyclic hydrocarbons such as cyclopropane, 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, and carbon peroxide. Further, the above various compounds can be used as a mixture.

Of these, preferred are paraffinic hydrocarbons such as methane, ethane and propane; alcohols such as ethanol and methanol; ketones such as acetone and benzophenone; amines such as trimethylamine and triethylamine; carbon dioxide; It is carbon oxide, and carbon monoxide is particularly preferable. 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.

Various diamond gas-phase synthesis methods such as a CVD method, a PVD method, a PCVD method, or a combination thereof can be used for forming the diamond. ,Normal,
Various hot filament methods including the EACVD method, various DC plasma CVD methods including the thermal plasma method, microwave plasma CVD methods including the thermal plasma method, and the like can be suitably used.

The conditions for forming diamond are not particularly limited, and the reaction conditions usually used in the above-mentioned vapor phase synthesis method can be applied. For example, as the reaction pressure,
Usually, 10 ^-6 to 10 ³ Torr is preferable, and especially 1 to 7 Torr
It is preferably within the range of 60 Torr. If the reaction pressure is lower than 10 ^-6 Torr, the diamond formation rate may be slow. Also, if higher than 10 ³ Torr, as compared to the effect obtained when the 10 ³ Torr, there is no further effect.

Since the surface temperature of the substrate varies depending on the means for activating the carbon source gas and the like, it cannot be specified unconditionally, but is usually from room temperature to 1,200 ° C., preferably from room temperature to 1,100 ° C. The temperature should be within the range of ° C. If this temperature is lower than room temperature, formation of a crystalline diamond film may be insufficient. If the temperature exceeds 1,200 ° C., the formed diamond film is likely to be etched.

The reaction time is not particularly limited, and is preferably set appropriately in accordance with the diamond formation speed so that the diamond film has a desired thickness. 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 the range of 0.2 to 100 μm. Is good. If the film thickness is too small, the coating effect of the diamond film may not be sufficiently obtained. On the other hand, if the film thickness is too large, separation such as peeling of the diamond film may occur depending on use conditions.

As described above, a diamond film can be selectively formed on a substrate surface. The method of the present invention can selectively form an excellent diamond film pattern easily and with a high degree of freedom without danger of contamination of impurities, for example, in the production of various electronic materials such as semiconductor devices and the like. It can be suitably used in various fields related to diamond film pattern formation, such as the field of micromachining.

[0044]

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 forming process-A silicon wafer was used as a substrate. This silicon wafer was loaded into an electron beam evaporation apparatus, and an insulating layer made of SiO ₂ was formed on the entire front surface of the silicon wafer under the following evaporation conditions.

◎ Evaporation conditions Pressure; 1.2 × 10 ^-5 Torr Silicon wafer temperature; 200 ° C. Electron beam current; 30 mA Electron beam voltage: 10 kV Evaporation time: 15 minutes Next, the substrate on which the insulating layer was formed was removed from the evaporation apparatus. It was taken out, grease was applied to a part on the insulating layer, and dried.

Next, the part of the insulating material layer made of SiO ₂ , which was not covered with the pattern film, was etched by immersing the part of the substrate on which the grease was applied in a HF aqueous solution (concentration: 46 mol%) for one minute. Thereafter, the substrate was washed twice with pure water. By washing with pure water after washing with pure water, the grease partially applied was removed to obtain a substrate with a mask layer made of an insulating material. Thereafter, the substrate with the mask layer was further washed twice with acetone.

Next, the substrate with the mask layer is loaded into a chamber in a CVD apparatus, and the electric field plasma processing and the hydrogen plasma processing are performed under the following electric field plasma processing conditions and hydrogen plasma processing conditions. Repeated 5 times. The substrate surface not covered by the mask layer was subjected to electric field plasma treatment and hydrogen plasma treatment.

◎ Electric field plasma processing conditions Type and flow rate of gas supplied into the chamber; Hydrogen gas; 20 SCCM methane gas; Microwave power required to convert 50 SCCM gas into plasma;
350 W DC bias voltage applied to the substrate; -100 V Chamber pressure; 15 Torr Substrate temperature; 900 ° C. Electric field plasma processing time; 5 minutes ◎ Hydrogen plasma processing conditions Flow rate of hydrogen gas supplied into chamber; 100 SCC
Microwave power required to convert M gas into plasma;
350 W Pressure in chamber; 30 Torr Substrate temperature; 900 ° C. Time for hydrogen plasma treatment; 5 minutes.

-Masking Removal Step- Thereafter, the substrate with the mask made of an insulating material was immersed in an aqueous HF solution (concentration: 46 mol%) for 1 minute to remove the mask layer from the substrate. Then, the substrate after the above processing is
It was loaded into the chamber of the VD apparatus, and a diamond film was synthesized under the following conditions.

Diamond synthesis step Diamond synthesis conditions Type and flow rate of carbon source gas supplied into the chamber; CO gas; 10 SCCM H ₂ gas; 90 SCCM microwave power required to convert gas into plasma;
350 W Pressure in chamber; 40 Torr Substrate temperature; 900 ° C. Time for diamond synthesis; 10 minutes.

As a result, a diamond film was selectively formed on the substrate surface subjected to the electric field plasma treatment and the hydrogen plasma treatment. Further, in order to observe the difference in the nucleation density of diamond between the part subjected to the above-described electric field plasma treatment and the hydrogen plasma treatment and the part not subjected to the electric field plasma treatment and the hydrogen plasma treatment, a part subjected to the electric field plasma treatment and the hydrogen plasma treatment (processing part) The state of nucleation in each of the non-treated part and the untreated part (untreated part) was observed by SEM. As a result, the nucleation density is 2
It was found to be a remarkably high value of × 10 ¹⁰ pieces / cm ² , while the untreated portion was 4 × 10 ⁴ pieces / cm ² , showing a remarkably low value.

(Comparative Example 1) A diamond film was synthesized in the same manner as in Example 1 except that an ultrasonic damage treatment was performed under the following conditions instead of performing the electric field plasma processing step. did.

◎ Condition of ultrasonic scratching treatment A solution in which a substrate with a mask layer made of SiO ₂ is immersed; an acetone suspension containing diamond abrasive grains having a particle size of 5 to 12 μm at a ratio of 1% by weight Time of ultrasonic treatment 15 minutes As a result, the diamond film was formed on both the portion of the substrate that was subjected to the ultrasonic damage treatment and the portion that was not.

In order to observe the difference in the nucleation density of diamond between the portion subjected to the above-described ultrasonic damage treatment and the portion not subjected to the ultrasonic damage treatment, the portion subjected to the ultrasonic damage treatment (processed portion) and the portion not subjected to the ultrasonic damage treatment were treated. The state of nucleation in each of the portions (untreated portions) was observed by SEM. As a result, the nucleation density was 2 × 10 ⁸ /
cm ^{2, which} is significantly higher than that of the untreated part.
× 10 ⁴ pieces / cm ² .

Example 2 Example 2 was performed in the same manner as in Example 1 except that the masking removal step and the diamond synthesis step were reversed. As a result, a diamond film was selectively formed on the substrate surface subjected to the electric field plasma treatment and the hydrogen plasma treatment. That is, it was confirmed that the obtained diamond film was selectively formed only on the portion of the substrate that was subjected to the electric field plasma treatment and the hydrogen plasma treatment, and was not formed on other portions.

In order to observe the difference in the nucleation density of diamond between the portion subjected to the above-described electric field plasma treatment and the hydrogen plasma treatment and the portion not subjected to the electric field plasma treatment and the hydrogen plasma treatment, The nucleation state in each of the treated part) and the non-treated part (untreated part) was observed by SEM. As a result, the nucleation density was 2 × 10 ¹⁰ / cm
² and a very high value.
cm ² . As a result of observing the nucleation state before removing the SiO ₂ masking material, the nucleation density on the SiO ₂ masking layer was 7 × 10 ³ / cm ² . Even in this state, high selectivity is obtained.

(Comparative Example 2) In the same manner as in the above-mentioned Example 2, except that the ultrasonic scratching treatment was performed under the same conditions as in Comparative Example 1 instead of performing the electric field plasma processing step in the above-mentioned Example 2. Thus, a diamond film was synthesized. As a result, the diamond film was formed only on the portion of the substrate that had been subjected to the ultrasonic damage treatment.

In order to observe the difference in the nucleation density of diamond between the portion subjected to the above-described ultrasonic damage treatment and the portion not subjected to the ultrasonic damage treatment, the portion subjected to the ultrasonic damage treatment (processed portion) and the portion not subjected to the ultrasonic damage treatment were observed. The state of nucleation in each of the portions (untreated portions) was observed by SEM. As a result, the nucleation density was 2 × 10 ⁸ /
cm ^2, which was extremely high, while
Pieces / cm ² . In addition, as a result of observing the nucleation state before removing the SiO ₂ masking material, the nucleation density on the SiO ₂ masking layer was 4 × 10 ⁶ / cm ² .

Example 3 Pattern-Forming Step A silicon wafer was used as a substrate. Using a thermal oxidation furnace, this silicon wafer was previously immersed in an oxidizing gas atmosphere.
Oxidation treatment was performed at 00 ° C. for 4 hours. As a result, 0.3
A μm thermal oxide film was formed. Next, a resist (OFPR-800: manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied on the surface of the thermal oxide film to a thickness of 1 μm by a spin coater, and the surface is coated with
A 3 μm square hole was covered with a matrix provided at 3 μm intervals. After contact exposure from above,
By developing and rinsing, a resist matrix pattern was obtained. Next, the resist was immersed in a 1% aqueous solution of hydrogen fluoride to dissolve and remove the resist in the form of dots.

Next, the substrate with the silica film obtained above was loaded into a chamber in a CVD apparatus, and an electric field plasma treatment was performed under the following conditions.

Electric field plasma processing conditions Type and flow rate of gas supplied into the chamber; Hydrogen gas; 20 SCCM methane gas; 50 SCCM microwave power required to convert gas into plasma;
DC bias voltage applied to 350 W substrate; -100 V Pressure in chamber; 15 Torr Temperature of substrate; 900 ° C. Time of electric field plasma treatment; 5 minutes.

—Synthesis of Diamond— ◎ Diamond Synthesis Conditions Type and flow rate of carbon source gas supplied into the chamber; CO gas; 10 SCCM H ₂ gas; 90 SCCM microwave power required to turn gas into plasma;
350 W Pressure in chamber; 40 Torr Substrate temperature; 900 ° C. Time for diamond synthesis; 10 minutes.

As described above, a diamond film was formed only in a dot pattern of 3 μm square, and no diamond was formed in a portion masked with SiO ₂ .

Example 4 Si ₃ was used as a masking material.
Example 3 was carried out in the same manner as in Example 3 except that a mask layer was formed by magnetron sputtering under the conditions of N ₄ and a pressure of 0.002 Torr and an output of 50 W. As a result, as in Example 3, diamond was generated only in the dot pattern, and no diamond was generated in the portion masked with Si ₃ N ₄ .

[0065]

According to the present invention, it is possible to increase the density of initial diamond nuclei in a predetermined region of a substrate and selectively form a diamond film pattern of a predetermined shape having excellent adhesion.

Continuation of front page (56) References JP-A-3-115194 (JP, A) JP-A-3-215392 (JP, A) JP-A-62-297298 (JP, A) JP-A-4-357194 (JP) , A) JP-A-63-34927 (JP, A) YUGO et al. , "Generation of diamonds by electric field in plasma chemical vapor de position", Applied Physics Letters, Vol. 58, No. 10, 11 Mar. 1991, p. 1036-1038 (58) Field surveyed (Int. Cl. ⁷ , DB name) C30B 1/00-35/00 H01L 21/205 CA (STN) JICST file (JOIS)

Claims (5)

(57) [Claims] After forming a pattern on a substrate with a masking material, an electric field plasma process (excluding a hydrogen plasma process) is performed.
Good. ), And then performing a hydrogen plasma treatment to synthesize diamond by a gas phase method. 2. The method according to claim 1, wherein the masking material is an electrically insulating masking material. 3. The method according to claim 2, wherein the masking material is removed after the diamond is synthesized. 4. An electrically insulating masking material comprising silica,
3. The method according to claim 2, wherein the method is at least one selected from silicon nitride and silicon carbide. 5. After forming a pattern on a substrate with a masking material, the substrate is subjected to a plasma treatment comprising a combination of an electric field plasma treatment and a hydrogen plasma treatment, and the masking material is removed. And a method for selectively forming diamond.