JPH0769793A - Selective growth method and selective epitaxial growth method for diamond crystals - Google Patents

Abstract

(57) [Summary] A diamond crystal is formed by forming an insulating mask on a semiconductor substrate and then applying a bias voltage of -20 V to -400 V or 40 V to 400 V to the substrate in a plasma containing at least carbon. After performing a plasma treatment for forming nuclei, a diamond crystal is selectively formed on a portion other than the insulating mask pattern by using a vapor phase synthesis method. [Effect] While diamond crystal nuclei are formed in a conductive region, by forming a region in which an insulating mask is formed that does not generate diamond crystal nuclei, diamond crystals are selectively formed in a region where many diamond crystal nuclei exist. Since the growth of diamond is promoted, a selective growth method of diamond crystals can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a selective growth method or a selective epitaxial growth method for a diamond crystal, and more particularly to a method for forming a selective single crystal film or a selective epitaxial single crystal film of a diamond crystal having high uniformity and smoothness.

[0002]

2. Description of the Related Art Diamond has a large band cap (5.5 eV) and a large carrier mobility (electron 1800
cm ² / V · S, holes 1600 cm ² / V · S), large thermal conductivity (20 W / cm · K), high hardness and excellent abrasion resistance, and other materials that cannot be obtained with other materials. It has the characteristics of

For this reason, in recent years, studies have been conducted on the synthesis of diamond from the vapor phase, particularly the chemical vapor deposition method (CVD method), and reports have been made on the selective growth method and the selective epitaxial growth method.

The conventional selective growth method of diamond crystals formed by the CVD method has been as follows. (1) According to the method disclosed in Japanese Unexamined Patent Publication No. 63-315598, after forming fine irregularities on a substrate by polishing, a mask is formed, and then irregularities other than the mask formation site are subjected to ion beam etching. After the removal, the mask is removed, and diamond crystals are selectively formed on the portion other than the portion where the mask is formed. (2) According to the method disclosed in Japanese Patent Laid-Open No. 62-297298, fine scratches are formed on a substrate, and then an amorphous material is formed in a pattern to selectively select a portion other than the putter. Form diamond crystals.

Further, there are the following conventional epitaxial growth methods and selective epitaxial growth methods by the CVD method. (3) As the substrate, cubic boron nitride (c-BN) having a homoepitaxial growth on a natural or artificial diamond crystal and a crystal structure close to that of a diamond crystal
By heteroepitaxial growth. Both of these have an epitaxial relationship with the base substrate, and a very smooth single crystal film can be obtained. Further, by forming a mask pattern made of a silicon oxide film on the diamond substrate, selective epitaxial growth can be performed on a portion other than the mask pattern forming portion. (4) When nickel is used as the substrate, diamond crystals are epitaxially grown in the form of particles (Abstracts of the 4th Diamond Symposium Lecture, page 13, January 22-23, 1991). (5) Further, JP-A-63-252997 describes that diamond crystals are epitaxially grown on a SiC substrate. Also, Applied Physic
s Letter, Vol. 62, No. 11, p. 1215 (19
1993), SW Walter et al. Reported that a diamond crystal with high crystal orientation can be obtained by placing a substrate on which a SiC film is formed in a carbon source plasma and then igniting a negative bias on the substrate. Has been reported.

However, the selective growth method and the epitaxial growth method of the diamond crystal formed in the above-mentioned conventional example have the following problems. In the selective growth methods (1) and (2), it is necessary to perform "damage treatment" for forming fine irregularities on the substrate in order to improve the generation density of diamond crystal nuclei. This process typically involves polishing the substrate with diamond abrasive. Also, the substrate is put in a liquid containing abrasive grains and ultrasonic vibration is applied. Etc. At this time, there is a problem that unevenness in scratches easily occurs and the reproducibility is poor. (3) A single crystal film obtained by epitaxial growth on a diamond or cubic boron nitride substrate is smooth and has good crystallinity, but the substrate is very expensive and not practical. (4) In the epitaxial growth of diamond crystals on a nickel substrate, a uniform epitaxial film cannot be obtained because the generation density of diamond crystal nuclei is low. Furthermore, the diamond crystal is eroded by nickel and the growth of the diamond crystal is hindered. (5) Even in the epitaxial growth on SiC, if the substrate is not pretreated, the generation density of diamond crystal nuclei is generally low and a uniform and flat epitaxial diamond crystal film cannot be obtained. The formation density of diamond crystal nuclei is improved by the bias treatment in plasma, but no report has been made on the selective growth method and the selective epitaxial growth method using this method.

[0007]

SUMMARY OF THE INVENTION In view of the problems of the above-mentioned conventional examples, the present invention has made a detailed study on the relationship between the formation of diamond crystal nuclei by a bias plasma treatment in a carbon source plasma and the substrate material. It is an object of the present invention to realize selective growth and further epitaxial growth by using a specific combination of master pattern materials formed on a substrate without using a “damage treatment” using diamond abrasive grains.

[0008]

Means for Solving the Problems The present invention, which achieves the above object, is intended to contain at least carbon after forming an insulating mask on a semiconductor substrate in a selective growth method of a diamond crystal using a vapor phase synthesis method. After applying a bias voltage of −20 V to −400 V or 40 V to 400 V to the substrate in plasma to form diamond crystal nuclei, a vapor phase synthesis method is used to form a pattern other than the insulating mask pattern. This is a selective growth method of a diamond crystal, which is characterized by selectively forming a diamond crystal in a portion. The diamond crystal nuclei are formed on the substrate in the conductive region (the exposed region of the semiconductor crystal substrate) by the effect of the bias plasma treatment of the substrate in the carbon source plasma. By creating a region that does not generate nuclei (region where an insulating mask is formed), diamond crystal growth is selectively promoted in a region where many diamond crystal nuclei are present, so "damage treatment" is performed. It is possible to realize a selective growth method of diamond crystals without any.

Further, the present invention provides a selective epitaxial growth method for diamond crystals using a vapor phase synthesis method,
After epitaxially growing a SiC layer on a semiconductor or insulator single crystal substrate, an insulating mask pattern is formed on the SiC layer, and the substrate is -20 V to -400 V or 40 V in a plasma containing at least carbon.
A plasma treatment for forming diamond crystal nuclei is applied by applying a bias voltage of ˜400 V, and thereafter, an epitaxial layer of diamond crystals is selectively formed on a portion other than the insulating mask pattern by using a vapor phase synthesis method. This is a selective epitaxial growth method for diamond crystals. Based on the same principle as the selective growth method described above, a region where diamond crystal nuclei are formed
The use of the C single crystal layer enables selective epitaxial growth in which a diamond crystal is selectively epitaxially grown in a portion other than the master pattern.

The present invention will be described below with reference to schematic drawings.
FIG. 1 is a schematic diagram of the selective growth of the present invention. First, the base 1
An insulating master pattern 2 is formed on the upper surface [Fig. 1
(A)]. Next, by the bias plasma treatment, the diamond crystal nuclei 3 are formed in the region where the insulating master pattern 2 is not formed [FIG. 1 (b)], and further the normal diamond crystal formation is performed, whereby the insulating master pattern 2 is formed. A polycrystalline diamond crystal layer 4 is formed in a region where 2 is not formed [FIG. 1 (c)].

FIG. 2 is a schematic view of the selective epitaxial growth of the present invention. First, the single crystal SiC film 22 is formed on the substrate 21.
After forming [Fig. 2 (a)], the insulating master pattern 2 is formed.
3 is formed [FIG. 2 (b)]. Next, by the bias plasma treatment, the diamond epitaxial crystal nuclei 24 are formed in the region where the insulating master pattern 23 is not formed [FIG. 2 (c)], and further the normal diamond crystal formation is performed, whereby the insulating master is formed. A diamond crystal epitaxial layer 25 is formed in a region where the pattern 23 is not formed [FIG. 2 (d)].

The epitaxial growth referred to in the present invention means that a crystal having a certain orientation relationship with its crystal orientation grows on an underlying single crystal substrate. For example, on the SiC single crystal thin film used in the present invention, SiC {10
A diamond crystal {100} plane is present on the 0} plane and S
A diamond crystal {111} plane is formed on the iC {111} plane.

The plasma treatment for applying a bias to the substrate in the carbon source plasma as referred to in the present invention is to make a raw material gas containing at least carbon into plasma, place the substrate in the plasma, and further apply a bias to the substrate. Is applied to activate the substrate surface to form diamond crystal nuclei. By this plasma treatment, a large number of diamond crystal nuclei are formed, so that the amount of diamond crystals deposited is increased and a diamond single crystal film is formed.

As the raw material gas for the plasma treatment method, hydrocarbons such as methane, ethane, ethylene and acetylene as a carbon source, oxygen-containing organic compounds such as ethyl alcohol, methyl alcohol and acetone, and trichloroethylene and carbon tetrachloride are used. The halogenated carbon can be used, and a gas such as hydrogen, oxygen, argon or helium is appropriately added. At this time, the addition amount of the carbon source gas is set to about 4% to 50% of the total raw material gas. At this time, the amount of the carbon source gas added is preferably about 4% to 50% of the total raw material gas. If the amount of the carbon source gas added is less than 4%, the plasma treatment has no effect and no crystal nucleus formation is observed. 50% again
When it exceeds, crystallinity deterioration of the diamond crystal is observed such as formation of graphite crystal nuclei.

As a plasma generation method, a known high-frequency plasma generator, microwave plasma generator, E
A CR (electron cyclotron resonance) plasma generator or the like can be used.

The bias applied to the substrate may be either positive or negative. An unclear point covers the mechanism of diamond crystal nucleation by applying this bias, but in the case of negative bias,
It is considered that the carbon source ions collide with the substrate and the carbon diffuses into the substrate to form diamond crystal nuclei. Further, in the case of a positive bias, it is considered that electron irradiation occurs on the substrate surface, the surface is activated and the reactivity advances, and diamond crystal nuclei are easily formed. In the case of a negative bias, the value of the bias applied to the substrate is preferably −20 V or higher and −400 V or lower. If it is less than -20 V, the bias application effect is not exerted, and if it is greater than -400 V, the effect of etching the nickel layer and the base is large, the crystal nucleus formation of the diamond crystal is not formed, and the diamond crystal does not precipitate. The negative bias applied to the substrate is generally a DC bias, but even if a high frequency bias is applied, a negative bias is generated due to its self bias, which is substantially the same as when a DC negative bias is applied. Have an effect.
At this time, it is preferable that the value of the self-bias is the same as that of the DC bias. Therefore, for example, 1
The plasma treatment may be performed while applying a high frequency bias of 3.56 MHz to the substrate. Furthermore, in the case of a positive bias, it is preferably 40 V or more and 400 V or less. If it is less than 40 V, the bias application effect is not exerted. If it is more than 400 V, the substrate is irradiated with electrons, the substrate temperature rises, and the diamond crystal is easily graphitized.

The plasma treatment time varies depending on the plasma output, the carbon source concentration, the bias voltage, etc., and cannot be generally stated, but it is generally about 1 minute to 1 hour.

About 10 ⁶ pieces / cm ² to 10 ¹⁰ pieces / cm ² of diamond crystal nuclei are formed on the substrate by the above plasma treatment, and then a diamond crystal film is obtained by using a normal vapor phase synthetic diamond forming method. To be
The size of this diamond crystal nucleus is about 10 to 100 in diameter.
It can be confirmed by a scanning electron microscope or the like.

The substrate used in the present invention is a substrate having a semiconductor single crystal layer on at least the surface. As the semiconductor single crystal layer, silicon single crystal, germanium single crystal, S
An iC single crystal, a gallium arsenide single crystal, an indium phosphide single crystal, or the like can be used. Further, the above-mentioned semiconductor crystal layer may be formed on the insulating substrate. In this case, as the insulating substrate, quartz single crystal, alumina single crystal, magnesium oxide single crystal, spinel single crystal, lithium niobate single crystal, lithium tantalate single crystal, strontium titanate single crystal or the like can be used.

In the present invention, it is necessary to form a SiC single crystal film on a substrate in order to epitaxially grow a diamond crystal. In this case, the film thickness is 10n
It is desirable to make it m or more. This is because if the thickness is less than 10 nm, the SiC film is scattered during the plasma treatment, and the effect of forming the SiC film is lost, so that epitaxial growth of diamond crystals cannot be seen. Therefore, the SiC film thickness is set to 10 nm or more, preferably 50 nm or more. Si
The method for forming the C film is not limited to a specific method, and any method may be used as long as a single crystal SiC layer can be formed on the substrate. For example, a thermal CVD method, a plasma CVD method, a photo CVD method, An ion plating vapor deposition method, a high frequency sputtering method, a direct current sputtering method, a magnetron sputtering method, a facing sputtering method or the like can be used.
The synthesis conditions differ depending on each synthesis method and cannot be generally stated. For example, in the case of the thermal CVD method, C ₃ H ₈ —SiH ₂ C is used.
The l ₂ -H ₂ gas mixture as a raw material gas, pressure: atmospheric pressure,
By setting the reaction temperature to 1050 ° C., the SiC single crystal film can be formed on the silicon single crystal substrate.

Next, the insulating mask pattern used in the present invention has a specific resistance of about 10 ⁸ Ω · cm or more, and silicon oxide, silicon nitride, aluminum oxide, silicon nitride, strontium titanate. , Various oxides, such as zirconia oxide, nitrides, and inclusions thereof can be used. Molybdenum and silicon carbide cannot be used. As a method of forming these mask patterns, a known optical drawing method or the like can be used. Since the effect of bias application during plasma processing does not occur on these insulating mask patterns, diamond nucleation does not occur. Therefore, the diamond crystal is selectively formed only in the portion (semiconductor crystal layer region) other than where the mask pattern is formed.

Further, in the present invention, the diamond crystal by the vapor phase synthesis method can be formed by using the CVD (chemical vapor deposition method) and the combustion flame method described below.

As the CVD method, hot filament CVD is used.
Method, microwave CVD method, magnetic field microwave CVD method,
A direct current plasma CVD method, an RF plasma CVD method or the like can be adopted.

As the carbon source of the raw material gas using the above CVD method, hydrocarbon gas such as methane, ethane, ethylene and acetylene, liquid organic compound such as alcohol and acetone, carbon monoxide or halogen carbon can be used. . Further, a gas containing hydrogen, oxygen, chlorine, or fluorine can be added as appropriate.

However, high quality diamond crystals
When forming an epitaxial single crystal film, the source gas is
Contain at least hydrogen, carbon and oxygen elements
is necessary. In this case, all of the above elements in one source gas
The raw material gas containing any element may also be included.
You may combine two or more types of the cloth. In this case, the raw material
The carbon source concentration in the gas may be 20% or less. here
The carbon source concentration is defined as (carbon source gas flow rate) x (carbon source gas
The number of carbon atoms in the gas) / (total raw material gas flow rate) x 100
It is the concentration passed. The number of carbon atoms in the carbon source gas is
For example, methane (CH _Four ) Is 1, propane (C₃ H₈ )
Then 3, acetone (CH₃ COCH₃ ) Will be 3.
The reason why the carbon source concentration is 20% or less is that the diamond
Suppresses the degree of supersaturation of crystal and suppresses the growth of amorphous carbon
It is to control. There is no lower limit, but 0.01% or less
Is when a practical diamond crystal formation rate cannot be obtained.
There is a match.

Further, in the CVD method, the ratio (O / C) of the number of atoms of oxygen and carbon in the source gas is 0.2 ≦ O / C ≦
1.2, preferably 0.5 ≦ O / C ≦ 1.1 is preferable. If it is less than 0.2, it may not be possible to obtain a high-quality diamond crystal due to no effect of addition, and if it exceeds 1.2, it may not be possible to obtain a practically usable diamond formation rate due to the etching effect of oxygen. O above
To adjust the / C value, for example, O ₂ , H ₂ O, N ₂ O
An oxygen-added gas such as the above can be added to the raw material gas.

In the combustion flame method, an oxygen-acetylene flame is used, and the value of the molar ratio of oxygen and acetylene in the main raw material gas is 0.85≤O ₂ / C ₂ H ₂ ≤1.0. And preferably 0.9 ≦ O ₂ / C ₂ H ₂ ≦ 0.99
With this, it is possible to form a diamond crystal film having good crystallinity and a relatively high growth rate (tens of μm / hr).

The diamond crystal selective growth film and the selective epitaxial film of the present invention are especially heat sinks (heat removal materials).
And is suitable as a semiconductor device. Diamond crystals have the highest thermal conductivity [2000 W / (m
k)], it is possible to significantly improve the heat dissipation effect of the semiconductor device by creating or mounting various semiconductor devices, such as a microwave oscillator and a laser diode, on the diamond crystal epitaxial film. it can. Also, in nature, the two isotopes ¹³ C of ¹² C and the atomic weight 13 of atomic weight 12 98.9%, respectively and 1.
It is present at a rate of 1%. The thermal conductivity of the diamond crystal described above is the case when "natural carbon" is used, but the thermal conductivity is further improved by increasing the ratio of ¹² C having an atomic weight of 12. For example, by reducing the case of ¹³ C to about 0.1%, the thermal conductivity will be 3000 W / (m ·
Improve to K). Also in the present invention, a suitable heat sink having higher thermal conductivity can be prepared by using a carbon raw material having high isotope purity.

Further, a semiconductor diamond crystal can be formed by adding an appropriate do band into the diamond crystal selective growth film and the selective epitaxial crystal film. This semiconductor diamond crystal layer may be formed on the base body, or the semiconductor diamond crystal layer may be laminated after forming the insulating diamond crystal layer on the base body. Since the diamond selective epitaxial crystal layer is a single crystal layer, it has high electron and hole mobilities and good semiconductor characteristics. In order to form the p-type semiconductor layer, a method of applying a gas containing boron in the raw material gas, and when a liquid carbon source is used for alcohol or the like, a boron source such as boric acid is added to the liquid carbon source. And the ion implantation method of implanting boron ions into the diamond crystal can be used. Further, in order to form the n-type semiconductor layer, a method of applying a gas containing phosphorus, lithium, and sodium in the source gas, and when a liquid carbon source such as alcohol is used, phosphorus and lithium are contained in the liquid carbon source. , A method of adding a content such as sodium, further phosphorus,
An ion implantation method in which lithium or sodium ions are implanted into a diamond crystal can be used.

[0030]

EXAMPLES Next, the present invention will be described in detail based on examples.

Example 1 In this example, the plasma treatment and the synthesis of diamond crystals were performed by using the microwave plasma CVD method shown in FIG.

In FIG. 3, 31 is a quartz reaction tube, 32 is a raw material gas introduction port, to which a gas cylinder (not shown), a gas flow rate controller, and a valve are connected. A gas exhaust port 33 is connected to a turbo molecular pump (not shown), a dry pump, a valve, and a pressure adjusting valve. A microwave waveguide 34 is connected to a microwave power source (not shown). A mesh electrode 35 is grounded to the ground. 36 is a base, 3
Reference numeral 7 denotes a substrate holder to which a substrate bias applying power source 38 is connected.

First, a silicon single crystal substrate (1 inch diameter,
Known optical drawing method on the (100) plane and plasma CV
A silicon oxide mask pattern having a width of 10 μm is formed by using the D method.
The layers were formed with a pitch of 10 μm and a thickness of 200 nm. This substrate is put in a microwave plasma CVD apparatus, and first,
Plasma treatment is performed. Plasma treatment conditions are methane (2
5%)-Hydrogen gas was used, pressure was 30 Torr, microwave output was 250 W, substrate bias was -75 V, and treatment time was 30 minutes. As a result of observing the diamond crystal nuclei formed in the exposed region of the silicon single crystal substrate with a scanning electron microscope, about 2 × 10 ⁸ diamond crystal nuclei having a diameter of 10 to 50 nm / cm ^{2 were} formed.

Subsequently, diamond crystals were formed using the same apparatus. The conditions for forming diamond crystals were ethyl alcohol (1%)-hydrogen system, pressure: 50 Torr, microwave output: 600 W, substrate temperature: 850 ° C., synthesis time: 5 hours, and substrate potential: earth. When the diamond crystal obtained as described above was observed by a scanning electron microscope, it was confirmed that a diamond film was selectively formed in a thickness of about 4 μm in a region other than the silicon oxide mask pattern forming portion. .

<Example 2-5, Comparative Example 1-2> Plasma treatment and diamond crystals were formed in the same manner as in Example 1 except that the mask pattern material was changed. The mask patterns are all formed by known plasma CVD, sputtering, vapor deposition, or the like, and are amorphous or polycrystalline films. The deposited diamond crystals were observed with a scanning electron microscope. The results are shown in Table 1.

[0036]

[Table 1] As is clear from Table 1, in Example 2-4, by using the insulating mask pattern, diamond crystals were formed with good selectivity in the region other than the mask pattern. Further, when the metal or semiconductor mask patterns of Comparative Examples 1 and 2 were used, selectivity was not observed and diamond crystals were formed on the entire surface of the substrate.

Example 5 First, a silicon carbide single crystal film having a thickness of 500 nm was formed on a silicon single crystal substrate (1 inch diameter, {111} plane) by a known thermal CVD method.

Next, a silicon oxide pattern is formed on this substrate by a known optical drawing method. The pattern film thickness was 0.5 μm, and the line width was 10 μm de 10 μm pitch.

This substrate is put in a known ECR plasma CVD apparatus, and plasma treatment is first performed. The plasma treatment conditions are ethyl alcohol (20%)-hydrogen-argon gas, pressure: 1 Torr, microwave output: 300.
W, substrate bias: -75 V, processing time: 1 hour.

Subsequently, diamond crystals were formed using the same apparatus. The conditions for forming the diamond crystal were carbon monoxide (5%)-hydrogen system, pressure: 0.5 Torr, microwave output: 800 W, substrate temperature: 850 ° C., synthesis time: 8 hours, and substrate potential was earth. When the diamond crystal thus obtained was observed by a scanning electron microscope, it was found that the diamond crystal having good flatness was selectively formed in a thickness of about 4 μm only on the portion other than the silicon oxide pattern. Do you get it. Further, when this diamond crystal film was examined by using a reflection type electron beam diffractometer, it was found to be a single crystal film epitaxially grown on the diamond {111} plane.

<Example 6-11, Comparative Example 3-5> Diamond crystals were formed in the same manner as in Example 5 except that the substrate bias during the plasma treatment was changed. In the ninth embodiment, 13.5 is used instead of the DC bias.
A high frequency bias of 6 MHz was applied, and the value of the self bias was used as the bias voltage. The precipitate was observed with a scanning electron microscope, and the crystallinity was evaluated with a reflection electron beam diffractometer. The results are shown in Table 2.

[0042]

[Table 2] As is clear from Table 2, in Example 6-11, it was possible to obtain a diamond crystal epitaxial layer having good flatness. Further, as shown in Comparative Example 3-5, when the substrate bias was 0 or low, an increase in diamond nucleus generation was not observed, and a uniform film with good flatness could not be obtained.

[0043]

As described above, the diamond crystal nuclei are formed on the substrate in the conductive region (the exposed region of the semiconductor crystal substrate) by the effect of the bias plasma treatment of the substrate in the carbon source plasma. On the other hand, the growth of diamond crystals was promoted in the region where a large number of diamond crystal nuclei existed by forming the region (the region where the insulating mask was formed) which did not produce the effect of the bias treatment and did not form the diamond crystal nuclei. Therefore, the selective growth method of the diamond crystal could be realized without carrying out the "damage treatment".

Further, based on the same principle as the selective growth method described above, a region where diamond crystal nuclei are formed is further made into Si.
By using the C single crystal layer, selective epitaxial growth in which a diamond crystal is selectively epitaxially grown in a portion other than the master pattern has become possible.

Such a diamond crystal is particularly excellent as an electronic material and a heat sink.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a diamond crystal epitaxial growth method according to the present invention.

FIG. 2 is a schematic diagram of a selective epitaxial growth method for diamond crystals according to the present invention.

FIG. 3 is a microwave plasma C according to an embodiment of the present invention.
It is a schematic diagram of diamond formation by the VD method.

[Explanation of symbols]

 1, 21 Substrate 2.23 Insulating mask pattern 3 Tiremond crystal nucleus 4 Polycrystalline tire mond layer 22 SiC single crystal layer 24 Diamond epitaxial crystal nucleus 25 Diamond epitaxial crystal layer 31 Quartz reaction tube 32 Raw material gas inlet 33 Gas outlet 34 microwave waveguide 35 mesh electrode 36 substrate 37 substrate holder 38 bias power supply

Claims (2)

[Claims] 1. In a selective growth method of diamond crystals using a vapor phase synthesis method, after forming an insulating mask on a semiconductor substrate, the substrate is -20 V to -400 V or at least in a plasma containing carbon. 40V-400
The method is characterized in that, after applying a bias voltage of V to perform a plasma treatment for forming diamond crystal nuclei, a diamond crystal is selectively formed on a portion other than the insulating mask pattern by using a vapor phase synthesis method. Selective growth method for diamond crystals. 2. In a selective epitaxial growth method for diamond crystals using a vapor phase synthesis method, after an SiC layer is epitaxially grown on a semiconductor or insulator single crystal substrate, an insulating mask pattern is formed on the SiC layer. A plasma treatment for forming diamond crystal nuclei by applying a bias voltage of -20 V to -400 V or 40 V to 400 V to the substrate in a plasma containing at least carbon, and then using a gas phase synthesis method. A selective epitaxial growth method for diamond crystals, wherein an epitaxial layer of diamond crystals is selectively formed on a portion other than the insulating mask pattern.