JP3248763B2 - Selective diamond formation - 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 diamond, and more particularly, to a method for forming a member which can be suitably used for a high-performance semiconductor device, heat sink, electronic material, or the like. However, it is a method of selective formation of diamond, and, with high selectivity of diamond, to a desired size and shape with high dimensional accuracy,
The present invention relates to a method for selectively forming diamond which can be formed easily and with good reproducibility by a simple operation.

[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 diamond 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. More recently, technology has been developed to selectively form a diamond film with a fine pattern 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 diamond on the surface of a substrate by such a vapor phase method, for example,
There are methods described in JP-A-2-30697 and JP-A-3-205397.

[0004] The former is a method of forming a pattern using a mask material on the surface of a substrate subjected to a scratch treatment, removing the pattern by etching, and forming diamond on the surface of the substrate by a vapor phase method. The latter is a method in which a mask material is applied to the substrate surface, anodization is performed, the non-mask portion is made porous, and diamond is formed by a gas phase method.

However, in the former method, there is a problem that the strength of the substrate is reduced due to the etching treatment or the solvent treatment of the substrate surface. Further, the latter method has a problem that the strength of the porous portion of the substrate is not sufficient, and diamond cannot be obtained with high selectivity. Therefore, with these methods, diamond having a desired shape and size with high selectivity cannot be manufactured with high dimensional accuracy.

[0006] The present invention solves the above problems,
Diamonds suitable for a wide range of fields including electronic devices such as high-performance semiconductor devices and heat sinks can be easily and easily reproduced to a desired size and shape with high selectivity, dimensional accuracy, and simple operation. An object of the present invention is to provide a method for selectively forming diamond that can be formed well.

[0007]

Means for Solving the Problems In order to solve the above problems, the present inventors have conducted intensive studies. As a result, the porous portion of the silicon substrate on which the mask pattern has been formed by the anodizing method is further thermally oxidized. The SiO
_Two . Thereafter, it has been found that, when the surface of the silicon substrate is subjected to an electric field treatment or a scratching treatment, diamond having a desired shape and size can be obtained with high selectivity with high dimensional accuracy.

That is, claim 1 for solving the above-mentioned problem.
In the invention described in (1), a mask pattern is formed on the surface of a silicon substrate, and the mask pattern is removed after a non-mask portion of the silicon substrate is made porous by anodization.
And then thermally oxidizing the porous layer to form SiO 2
_This is a method for selectively forming diamond, characterized in that it is subjected to an electric field treatment or a scratching treatment, and then a diamond synthesis is performed by a gas phase method.

Hereinafter, the present invention will be described in detail.

The method of the present invention includes: 1) a step of forming a mask pattern on a surface of a silicon substrate using a mask pattern forming material (hereinafter, referred to as a mask pattern forming step); 2) a non-mask portion on the surface of the silicon substrate. Is made porous by anodization and then thermally oxidized to form S
iO ₂ -forming step (hereinafter, referred to as porous and SiO ₂ -forming step); 3) electric field treatment of the surface of the silicon substrate (hereinafter, referred to as a step).
This is called an electric field processing step. ) Or a scratching process (hereinafter, referred to as a scratching process), and 4) a process of forming diamond on the surface of the silicon substrate by a vapor phase method (hereinafter, referred to as a diamond forming process). Having.

The steps will be described below in order.

1) Mask Pattern Forming Step In the mask pattern forming step, a mask pattern having a desired shape and size is formed on the surface of the silicon substrate using a specific mask pattern forming material.

To form a mask pattern, a lithography technique can be used.

More specifically, first, as shown in FIG. 7, a coating solution for forming a mask pattern containing a resist agent such as a photoresist is applied to the entire surface of the silicon substrate 1 and dried to form a resist layer. 5 is formed. Next, as shown in FIG. 7, the resist layer 5 is exposed to light such as ultraviolet rays through a photomask 6 having the same pattern as the target mask pattern as shown in FIG. In addition,
The photomask 6 shown in FIG. 8 has a light blocking part 6a and a light transmitting part 6b. Thereafter, a method of removing the exposed portion and forming a mask pattern 5a having the same size and shape as the desired pattern as shown in FIG. 6 on the surface of the silicon substrate 1 can be mentioned.

As another method, first, a coating liquid for forming a mask pattern containing a resist agent such as a photoresist is applied to the entire surface of a silicon substrate, and the coating liquid is dried to form a resist layer. Next, the resist layer is exposed to light such as ultraviolet light through a photomask having a pattern opposite to a desired mask pattern. Then, a method of removing the unexposed portion and forming a mask pattern having the same size and shape as the desired pattern on the surface of the silicon substrate can be given.

The silicon substrate is not particularly limited, and may be P-type or N-type. The specific resistance of the silicon substrate is usually 10 ⁻³ to 10 ⁻³ Ω · cm.

As the resist agent, in addition to a photoresist, a resist for an electron beam or an X-ray can be used.

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 negative photoresists include, for example, LMR-33 manufactured by Fuji Pharmaceutical Co., Ltd., and OMR-83 and OMR-85 manufactured by Tokyo Ohka Kogyo Co., Ltd. Commercially available positive photoresists include OFPR- manufactured by Tokyo Ohka Kogyo Co., Ltd.
2 and OFPR-800.

The method of preparing the coating liquid for forming a mask pattern is not particularly limited, and various known methods can be employed.

Examples of the method of applying the coating liquid for forming a mask pattern 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 mask pattern, the resist is usually dried to obtain a resist layer. The thickness of the resist layer when dried is not particularly limited, but is usually about 0.5 to 3 μm.

The mask pattern can be formed by irradiating the resist layer with light such as ultraviolet rays through a photomask and exposing the resist layer to development and rinsing.

Examples of the method of exposure by irradiating the above-mentioned light such as ultraviolet rays include a contact exposure method, a proximity exposure method, and a projection exposure method. Can be selected and used.

As described above, in this mask pattern forming step, for example, as shown in FIG.
A mask pattern 5a is formed on the surface of the substrate.

2) Step of making porous and forming SiO _{2 In the} step of forming porous and forming SiO ₂ , after the non-mask portion on the surface of the silicon substrate is made porous by anodization, the mask pattern is dissolved and removed. Thereafter, the silicon substrate is converted to SiO ₂ by thermal oxidation.

In the porous formation by the anodization method, the silicon substrate is electrolyzed in an aqueous solution of, for example, hydrogen fluoride to form a porous surface on the surface of the silicon substrate as shown in FIG. Layer 4 is formed. At this time, the portion of the silicon substrate where the mask pattern is formed is not made porous.

Examples of the aqueous solution include an aqueous solution of hydrogen fluoride (HF: H ₂ O = 1: 1 in volume ratio), a mixed solution of an aqueous solution of hydrogen fluoride and ethanol (HF content of 5 to 50 V).
ol. %) And the like.

The electrolysis can be performed, for example, by flowing a current of 1 to 300 mA / cm ² in a container containing the aqueous solution, using a silicon substrate as an anode and platinum, carbon, gold or the like as a cathode. it can.

The electrolysis time is usually from 5 seconds to 30 seconds.
Minutes.

If the time is too short, the porosification may be insufficient, while if it is too long, the porosification may progress to the back of the mask portion.

The thickness of the porous layer is usually 0.1.
005 to 500 μm. This thickness can be adjusted by appropriately changing the concentration of the aqueous solution such as the above-mentioned aqueous solution of hydrogen fluoride, the current or time in electrolysis, or the like.

If the thickness is too small, the selectivity of diamond may decrease. On the other hand, if the thickness is too large, porosity may progress to the back surface of the mask portion and dimensional accuracy may decrease.

In the porous and SiO ₂ forming steps, the mask pattern is dissolved and removed after the silicon substrate is made porous.

For dissolving and removing the mask pattern, an appropriate method can be selected. For example, a method using plasma, a method using a solvent such as acetone, alcohol, cellosolve, a mixed solution of sulfuric acid and hydrogen peroxide, or a solvent such as dimethylformamide can be used. Alternatively, a commercially available solution exclusively for resist may be used.

In the porous and SiO ₂ conversion step, after the mask pattern is dissolved and removed, the porous layer on the silicon substrate is converted to SiO ₂ by thermal oxidation.

The thermal oxidation is performed at a temperature of 800 to 12000.
It can be performed by flowing oxygen gas in contact with the surface of the silicon substrate under the conditions of ° C., atmospheric pressure, or reduced pressure.

The time for the thermal oxidation is usually tens of minutes to several hours.

[0039] When the time is short, it may SiO ₂ reduction becomes insufficient, whereas when the long, will be turned into thick SiO ₂ Besides pore formation portions of the silicon substrate,
In the subsequent electric field treatment or scratching treatment, the initial nucleus for diamond generation may not be able to be generated.

In the conversion of the silicon substrate to SiO ₂ , the porous portion of the silicon substrate has a larger specific surface area than the other portions, and is therefore completely oxidized early.
The portion of the non-porous silicon substrate is also S
It is iO ₂ of.

The thickness of the SiO ₂ layer on the surface of the nonporous silicon substrate is 500 °
It is preferable that the thickness be less than or equal to 1
/ 2 or less.

In the porous and SiO ₂ conversion step, the pre-SiO ₂ conversion layer can be dissolved and removed by an appropriate method, if necessary.

As shown in FIG. 4, the porous layer 3 having the same pattern as the mask pattern is formed on the surface of the silicon substrate by the formation of the porous layer.

3) Electric Field Treatment Step In this electric field treatment step, the surface of the silicon substrate is treated with a plasma of a carbon-containing compound while applying a negative bias voltage to the silicon substrate.

As the negative bias voltage applied to the silicon substrate, for example, the DC bias on the silicon substrate side is in the range of -500 to -50 V, preferably -400 to -50 V.
The range is -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 −50 V is also preferably adopted.

The carbon-containing compound in the electric field treatment step is not particularly limited as long as it contains at least the carbon-containing compound, and may be a mixed gas containing hydrogen gas or the like. A gas commonly used or usable can be used.

Examples of the carbon-containing compound include various hydrocarbons (specifically, for example, alkanes such as methane, ethane, propane, butane, pentane, and hexane; ethylene, propylene, butene, and pentene). Alkenes such as benzene, aromatic hydrocarbons such as toluene,
A wide variety of hydrocarbons such as cycloalkanes such as cyclopentane and cyclohexane), oxygen-containing hydrocarbons (specifically, alcohols such as methanol, ethanol, propanol, ethylene glycol and benzyl alcohol, acetone) And various carbon-containing hydrocarbons such as ketones such as methyl ethyl ketone, cyclohexanone and acetophenone, carboxylic acids such as acetic acid and propionic acid, and ethers such as dimethyl ether, diethyl ether and tetrahydrofuran), CO and CO _2. Compounds can be mentioned.

Among these, particularly preferred are, for example, methane, methanol, acetone, CO and the like. These may be used alone or in a combination of two or more.

When a mixed gas of the above-mentioned carbon-containing compound and hydrogen is used, the content of the carbon-containing compound relative to the whole mixed gas is usually 0.1 to 99% by volume, and preferably 0.1 to 99% by volume.
It is desirable that the ratio be 5 to 80% by volume.

The method for converting the carbon-containing compound into plasma is not particularly limited, and a plasma processing method by various methods such as a general method used in the gas phase synthesis of diamond or diamond film is applied. It is possible. Specifically, for example, microwave plasma CVD
Method, high frequency plasma CVD method, hot filament method, EC
The R method and the like, or a combination method thereof and the like can be mentioned. Among these, in particular, microwave plasma CV
A plasma processing method by the method D or the like can be suitably adopted.

[0051] The reaction conditions of the electric field treatment step, can be carried out by conditions conventional, for example the pressure of the reaction system of 10 ^-3 to 10 ³ Torr range, the temperature of the silicon substrate at room temperature ～1,100 ° C. It can be suitably performed by appropriately selecting the range.

The processing time is usually from 1 second to 30 minutes.

If the treatment time is too short, the proportion of nuclei generated for diamond generation is reduced, and even if diamond formation is performed thereafter, it may not be possible to obtain diamond of the desired shape and size. On the other hand, if too long, it may become nuclei to generate in SiO ₂ phased portions in the silicon substrate, it may not be possible to obtain a diamond selectively.

By this electric field treatment step, diamond generating nuclei 7 are formed on the surface of the silicon substrate 1 as shown in FIG.

In the present invention, the diamond initial nuclei are formed on the surface of the silicon substrate at a high density by the electric field treatment step of treating the silicon substrate with the plasma of the carbon-containing compound while applying a negative bias voltage thereto or by the damage treatment step described later. To generate efficiently. As a result, the generation rate during diamond formation is significantly improved, and high-quality diamond can be manufactured.

In the present invention, in order to generate an initial nucleus for diamond generation on the surface of a silicon substrate,
This electric field processing step may be employed, or a flaw treatment step described later may be employed.

In the present invention, since electric field processing is performed on a flat silicon substrate, nuclei for diamond generation are generated on the surface of the silicon substrate in the same shape and size as the mask pattern with high dimensional accuracy. Can be.

3) Damage treatment step In the damage treatment step, a scratch is formed on the surface of the silicon substrate as a nucleus for depositing diamond using abrasive grains.

The abrasive grains are not particularly limited as long as they are fine particles having a hardness higher than that of the silicon substrate.
Examples include particles such as SiC, CBN, and diamond.

Preferred among these are diamond grains.

The grain size of the abrasive grains is usually 0.5 to 500
μm, and preferably 0.5 to 100 μm.

If the particle size of the abrasive grains is not in the above range, the effect of damaging the silicon substrate is not sufficient, and a preferable nucleus for diamond deposition may not be formed.

Various methods can be selected for performing the scratching process using the abrasive grains. Usually, a silicon substrate is immersed in a liquid in which the abrasive grains are dispersed in a solvent, The irradiation can be performed by irradiating ultrasonic waves.

Examples of the solvent include alcohol, acetone and the like. Further, the amount of the abrasive particles dispersed in the solvent is usually 0.05 0.05 per 100 ml of the solvent.
10 to 10 g, preferably 0.1 to 5 g.

The time for the scratching process is appropriately selected according to the purpose, but is usually 3 seconds to 1 hour. If the time of the scratching treatment is too short, the rate of generation of nuclei for diamond generation becomes small, and it may not be possible to obtain a diamond having a desired shape and size even if diamond formation is performed thereafter. On the other hand, even if it is long, there is no effect corresponding to it.

In this scratching process, when ultrasonic waves are applied, the abrasive grains violently come into contact with the surface of the silicon substrate. Thereby, minute scratches can be made on the surface of the silicon substrate.

In this flaw treatment, after the flaw on the surface of the silicon substrate is completed, the porous silicon on the silicon substrate is removed using a hydrogen fluoride aqueous solution.
Flaws formed on the surface of the O ₂ -formed portion are dissolved and removed. The concentration of the aqueous hydrogen fluoride solution is usually 0.2 to 50%.
It is.

By this scratching process, diamond generating nuclei 7 are formed on the surface of the silicon substrate 1 as shown in FIG.

The minute flaws imparted to the surface of the silicon substrate by the above-mentioned flaw treatment serve as a point at which diamond initial nuclei are generated when diamond is formed.

4) Diamond Formation Step In this diamond formation step, diamond having the same pattern as the mask pattern is selectively formed on the surface of the silicon substrate.

As a method for forming diamond, various methods such as CVD, PVD, PCVD, or a combination thereof can be used. , Usually E
Various types of hot filament methods including the ACVD method, various types of DC plasma CVD methods including the thermal plasma method, and microwave plasma CVD methods including the thermal plasma method can be suitably used.

The carbon source gas used in these diamond forming methods is, for example, methane, ethane, propane,
Paraffinic hydrocarbons such as butane; olefinic hydrocarbons such as ethylene, propylene and butylene; acetylene;
Acetylene-based hydrocarbons such as allylene; diolefin-based hydrocarbons such as butadiene and allene; alicyclic hydrocarbons such as cyclopropane, cyclobutane, cyclopentane and cyclohexane; aromatics such as cyclobutadiene, benzene, toluene, xylene and naphthalene Hydrocarbons; 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; Examples thereof include carbon oxide 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.
Two or more kinds may be used in combination as a mixed gas or the like.

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 diamond are not particularly limited, and the reaction conditions usually used in the above-mentioned vapor phase synthesis method can be applied.

For example, the reaction pressure is usually 10 ⁻⁶ to
It is preferably 10 ³ Torr, particularly preferably in the range of 1 to 760 Torr.

If the reaction pressure is lower than 10 ^-6 Torr, the diamond formation rate may be slow.
In addition, if higher than 10 ³ Torr is, 10 ³ Tor
There may be no further effect compared to the effect obtained at r.

The surface temperature of the silicon substrate is as follows:
Since it differs 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 in the range of room temperature to 1,100 ° C.

If this temperature is lower than room temperature, the formation of crystalline diamond may be insufficient. On the other hand, when the temperature exceeds 1,200 ° C., the formed diamond is easily etched.

The reaction time is not particularly limited, and is preferably set appropriately according to the diamond forming speed so that the diamond has a desired thickness.

The thickness of the diamond to be formed may be appropriately determined according to the purpose of use and the like, and is not particularly limited in this sense.
It is better to select within the range of μm. If the thickness is too small, the coating effect of diamond may not be sufficiently obtained when the coating member is used. On the other hand, if the thickness is too large, separation such as peeling of diamond may occur depending on the use conditions. May occur. In addition, when using the obtained diamond under severe conditions such as a cutting tool, it is usually preferable to select the thickness in the range of 5 to 100 μm.

As described above, as shown in FIGS. 1 and 2, diamond 2 having a desired shape and size is selectively formed on the surface of silicon substrate 1 with high dimensional accuracy.

According to the method of the present invention, a diamond pattern having excellent dimensional accuracy can be formed with high selectivity. Such diamond having excellent dimensional accuracy can be suitably used in a wide field including various electronic materials such as semiconductor devices.

[0085]

Embodiments of the present invention will be specifically described below. The present invention is not limited to the following embodiments.

Example 1 Mask Pattern Forming Step A low-resistance p-type silicon substrate (resistivity ρ = 0.001 Ωcm) was used as a silicon substrate.

A coating liquid for forming a mask pattern was applied to the surface of the silicon substrate and dried to form a resist layer. Subsequently, using a photomask having the pattern shown in FIG. 8, the resist layer was exposed, developed, and rinsed to form a mask pattern having a 3 μm square dot mask pattern by a photolithography process.

More specifically, a positive photoresist (OFPR-800, manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied using a spinner at 3 × 10 ³ rpm so as to have a thickness of 1 μm. A resist layer was formed on the surface. After the application, the resist layer was dried by heating at 100 ° C. for 90 seconds. Then, ultraviolet rays were irradiated using a mask aligner (PLA-501FA) manufactured by Canon Inc.
As shown in FIG. 8, the intensity of 3 mW / cm ^{2 was} measured for 90 seconds.
The resist layer was exposed through a photomask 5 having a dot mask pattern of μm square. Subsequently, the silicon substrate was immersed in NMD-3 manufactured by the same company for 60 seconds to perform development, and after removing the exposed portion of the resist layer, the silicon substrate was rinsed with pure water.

Thus, when the line width is 3 μm and the interval is 3
A μm dot-shaped mask pattern was formed on the surface of the silicon substrate.

-Porosification and Thermal Oxidation Step- Under the following conditions, porosity formation by anodization, dissolution and removal of the mask pattern, and SiO ₂ formation by thermal oxidation were performed.

(Porousization) Aqueous solution used: mixture of hydrogen fluoride, water and ethanol (20%: 30%: 50%) Current: constant current of 10 mA / cm ² Processing time: 1 minute A porous layer having a thickness of about 5000 ° was formed on the surface of the silicon substrate.

(Dissolution and Removal of Mask Pattern) The mask pattern was dissolved and removed by immersing the silicon substrate in acetone.

(Formation of SiO ₂ ) An oxygen gas was flowed at a temperature of 1000 ° C. for 1 hour. Thereafter, the surface of the silicon substrate was treated with a 1% aqueous hydrogen fluoride solution for 1 minute.

-Electric field treatment step-Electric field treatment was performed under the following conditions.

Type and flow rate of gas used: mixed gas of CH ₄ and H ₂ (20/40 sccm) Synthesis conditions: reaction pressure 20 Torr, substrate bias -10
0 V, processing time 5 minutes Adoption method: microwave plasma CVD method (2.45 GHz)
z).

As described above, initial nuclei for diamond generation were formed on the surface of the silicon substrate.

—Diamond Formation Step— Diamond 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, silicon substrate temperature 9
00 ° C, synthesis time 1 hour Synthesis method (source gas excitation method): microwave plasma CVD
Method (2.45 GHz). As a result, it was possible to form a 3 μm square dot diamond with high dimensional accuracy and high selectivity on the surface of the silicon substrate.

(Example 2) Instead of the electric field treatment step in Example 1, the following scratching step was performed, and the diamond was formed in the same manner as in Example 1 except that the diamond forming conditions were changed as follows. The formation was performed.

-Scratching process- In an ultrasonic cleaning apparatus, 0.5 g of diamond particles having a particle size of 5 to 12 μm is dispersed in 50 ml of acetone, and at the same time, a silicon substrate made into SiO ₂ is immersed in this solution to damage the surface. The treatment was performed for 15 minutes. As a result, fine scratches were made on the surface of the silicon substrate.

Thereafter, the substrate surface was etched using buffered hydrofluoric acid (etching rate: 1000 ° / min).

As described above, initial nuclei for diamond generation were formed on the surface of the silicon substrate.

-Diamond forming step- Diamond 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, silicon substrate temperature 9
00 ° C, synthesis time 1 hour Synthesis method (source gas excitation method): microwave plasma CVD
Method (2.45 GHz).

As a result, 3 μm
It was possible to form diamonds having angular dot shapes with high dimensional accuracy and high selectivity.

[0106]

According to the present invention, diamond suitable for a wide range of fields including electronic devices such as high-performance semiconductor devices, electronic materials, heat sinks, etc., can be sized to a desired size and shape with high selectivity. It is possible to provide a method for selectively forming diamond, which can be formed with high accuracy, a simple operation, and high reproducibility.

[0107]

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a state in a cross section of a silicon substrate on which diamond is selectively formed.

FIG. 2 is a schematic explanatory view showing a state in which a silicon substrate on which diamond is selectively formed is viewed from above.

FIG. 3A is a schematic explanatory view showing a state in a cross section of a silicon substrate subjected to an electric field process. FIG.
(B) is a schematic explanatory view showing a state in a cross section of a silicon substrate subjected to a hydrogen fluoride aqueous solution treatment after performing a scratching treatment.

FIG. 4 is a schematic explanatory view showing a state in a cross section of a silicon substrate in which a mask pattern has been removed and a non-mask portion has been made into SiO ₂ .

FIG. 5 is a schematic explanatory view showing a state of a cross section of the silicon substrate after a non-mask portion of the silicon substrate is made porous.

FIG. 6 is a schematic explanatory view showing a state of a cross section of a silicon substrate on which a mask pattern is formed.

FIG. 7 is a schematic explanatory view showing a state in which a resist layer applied to the surface of a silicon substrate is exposed to ultraviolet rays via a photomask.

FIG. 8 is a schematic explanatory view showing an example of a photomask.

[Description of sign]

1 silicon substrate 2 Diamond 3 SiO ₂ layer 4 the porous layer 5 resist layer 5a mask pattern 6 photomask 6a light shielding portion 6b light transmitting unit 7 Diamond generating nuclei

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-30697 (JP, A) JP-A-51-2391 (JP, A) JP-A-3-70156 (JP, A) JP-A-4- 10419 (JP, A) JP-A-3-109295 (JP, A) JP-A-3-205397 (JP, A) JP-A-3-112898 (JP, A) JP-A-3-115194 (JP, A) JP-A-5-320910 (JP, A) JP-A-5-271942 (JP, A) JP-A-6-128086 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C30B 1/00-35/00

Claims (1)

(57) [Claims] To 1. A surface of a silicon substrate, forming a mask pattern, the unmasked portion is porous by anodization
After removing the mask pattern, then the porous layer
The SiO ₂ turned into by thermal oxidation, then subjected to electrical field processing or scratching process, then selectively forming method of diamond, characterized by performing the diamond synthesis by a gas phase method.