JP2024082981A - Diamond growth method and diamond growth apparatus - Google Patents

Abstract

【assignment】
The object of the present invention is to provide a method for growing diamond, which is capable of growing high-quality, large-diameter diamond even by plasma CVD using high-order mode microwaves.
SOLUTION
A diamond growth method including a growth step of growing diamond on a substrate by microwave plasma CVD, characterized in that in the growth step, the microwaves during diamond growth are in a higher order mode, and the substrate is heated while diamond is being grown in the higher order mode, thereby controlling the temperature of the substrate.
[Selected figure] Figure 4

Description

The present invention relates to a diamond growth method and a diamond growth apparatus.

Diamond has excellent physical properties such as high hardness, good thermal conductivity, high carrier mobility, and a wide band gap, and is therefore expected to be applied to various semiconductor elements and electronic devices. Artificially synthesized diamond is used for these semiconductor elements and electronic devices. There are two methods for diamond synthesis: growth using ultra-high pressure and vapor phase growth. For semiconductor applications, vapor phase growth (CVD growth) is attracting attention because it can produce large diameters (Patent Documents 1 to 3).

CVD growth is a method in which a substrate is placed inside a reaction tube, source gases and a carrier gas are flowed under normal or reduced pressure, and the source gases are decomposed and activated by pyrolysis or plasma to grow on the substrate.
When growing diamond by CVD, microwave plasma, DC plasma, hot filament method using filament such as tungsten is adopted, but microwave plasma method is attracting attention for single crystal growth. This microwave plasma growth is a method of activating reactive chemical species with microwaves and synthesizing, but microwaves have a short wavelength and need to resonate in a reaction vessel, so various ideas have been made. In addition, 915MHz is suitable for large diameter (Patent Document 4), but this wavelength is used for civil communication signal band, and radio wave has a long reach, so there are hurdles for industrial application of 915MHz microwave plasma CVD, and 2.45GHz band is mainly used.

In light of this, for example, Patent Document 5 discloses a method of resonating microwaves using mirrors (however, the diamond obtained is polycrystalline) and an improvement in the mode by combining microwave introduction tubes. Patent Document 6 describes that by changing the shape of the applicator (resonator) from rectangular to cylindrical, it is possible to form a film over a relatively large area. It is also said that by using low-order microwave modes (low-order modes are TMnm mode, TEnm mode, etc., where n or m is 0 or 1), it is possible to form a uniform film within the surface. As an example of a high-order mode, TM20 is mentioned, and it is described that it can process relatively large substrates, but it has been pointed out that in such high-order modes, microwaves become locally strong, creating areas with strong plasma, which causes uneven temperatures in the substrate and deteriorates the quality.

JP 2001-354491 A JP 2004-176132 A JP 2006-143561 A JP 2016-113303 A JP 2006-501122 A Japanese Patent Application Laid-Open No. 07-142195

Diamond substrates have thus been attracting attention for their heat dissipation properties, and the growth method suitable for single crystal substrates is microwave plasma growth, but plasma CVD using higher mode microwaves that allow for larger diameters has the problem of quality degradation due to uneven substrate temperature. As a result, only lower mode plasma, which is difficult to increase in diameter, can be used, and restrictions on the area that can be irradiated with plasma make it impossible to increase the diameter to a diameter of 300 mm or more.

The present invention has been made to solve the above problems, and aims to provide a diamond growth method and diamond growth apparatus that can grow high-quality, large-diameter diamonds even when using plasma CVD that uses high-order mode microwaves.

The present invention relates to a technology for artificially growing diamond on a semiconductor substrate to solve the above-mentioned problems, and more specifically, to a diamond growth method and diamond growth apparatus for growing single crystal diamond on a silicon substrate by CVD (chemical vapor deposition).
That is, the present invention has been made to achieve the above-mentioned object, and provides a diamond growth method including a growth step of growing diamond on a substrate by microwave plasma CVD, characterized in that in the growth step, the microwaves during diamond growth are made to be in a higher mode, and the substrate is heated while diamond is growing in the higher mode, thereby controlling the temperature of the substrate.
In this configuration, as a growth method that can address the issue of growing diamond on large-diameter substrates by microwave plasma CVD, when growing diamond on a substrate, a higher-order mode is actively adopted as the microwave plasma, increasing the area that can be irradiated with plasma, making it possible to increase the diameter, and further mitigating local concentration of plasma (reducing the plasma density in one place).In addition, by heating the substrate and absorbing temperature unevenness, it is possible to grow high-quality diamond.
Furthermore, in this configuration, diamond is grown vertically in areas with high plasma density, while lateral growth occurs in areas with low plasma density, which also contributes to a reduction in defects.
Therefore, it is possible to grow high quality, large diameter diamond.

In the growth step, the temperature of the substrate at each position within the substrate may be individually controlled depending on the position.
In this way, the temperature can be controlled individually according to the position within the substrate, so that the heating temperature can be increased in low-temperature parts of the substrate and decreased in high-temperature parts, absorbing temperature variations and making the temperature uniform within the substrate. This allows for more precise control of the substrate temperature, resulting in the growth of higher quality diamonds.

After the growth step, an additional growth step may be performed in which diamond is further grown on the diamond grown on the substrate using a hot filament CVD apparatus.
This makes it possible to grow even thicker diamond on a large-diameter substrate by growing further diamond on the diamond grown on the substrate by microwave plasma CVD using a hot filament CVD apparatus capable of large-diameter growth.

The substrate may be a silicon single crystal substrate.
In this configuration, since a silicon single crystal is used as the substrate, diamond can be grown on an inexpensive substrate.

The present invention also provides a diamond growth apparatus comprising a reaction vessel in which a substrate is housed and into which diamond raw material gas is introduced, and a waveguide connected to the reaction vessel for introducing microwaves into the reaction vessel, whereby plasma is generated in the reaction vessel by the microwaves introduced from the waveguide, and the raw material gas is decomposed and activated by the generated plasma to grow diamond on the substrate by CVD, characterized in that the diamond growth apparatus comprises a mode setting mechanism for changing the microwaves used for growing diamond to a higher mode, and a heating control mechanism for controlling the temperature of the substrate by heating the substrate while diamond is being grown in the higher mode.
In this device, when growing diamond on a substrate by microwave plasma CVD, the microwave can be set to a higher mode by the mode setting mechanism, which increases the area that can be irradiated with plasma, making it possible to increase the diameter, and further mitigates localized concentration of plasma (reducing the plasma density in one place).In addition, the heating control mechanism heats the stage to absorb temperature unevenness, making it possible to grow high-quality diamond.
Furthermore, this device allows diamond to grow vertically in areas with high plasma density, while lateral growth occurs in areas with low plasma density, which contributes to a reduction in defects.
Therefore, the present invention makes it possible to grow high quality, large diameter diamond.

The heating control mechanism may be a mechanism capable of individually controlling the temperature of the substrate at a position depending on the position within the substrate.
In this way, the heating control mechanism controls the temperature individually according to the position within the substrate, so that the heating temperature can be increased in low-temperature parts of the substrate and decreased in high-temperature parts of the substrate, absorbing temperature variations and making the temperature uniform within the substrate. This allows for more precise control of the substrate temperature, resulting in the growth of higher quality diamond.

As described above, the diamond growth method of the present invention makes it possible to grow high-quality, large-diameter diamonds even in plasma CVD using high-order mode microwaves. Also, the diamond growth apparatus of the present invention makes it possible to grow high-quality, large-diameter diamonds even in plasma CVD using high-order mode microwaves.
More specifically, the composition of the present invention allows for the growth of large diameter single crystal diamond.

FIG. 1 shows a conceptual diagram of a diamond substrate produced by growing diamond on a substrate using the diamond growth method of the present invention. 1 shows a schematic diagram of a diamond growth apparatus according to the present invention. 1 shows the relationship between the microwave mode and the microwave length when growing diamond using the diamond growth apparatus and growth method of the present invention. 1 shows a flow diagram of a diamond growth method of the present invention. 1 shows a conceptual diagram of a hot filament CVD apparatus. FIG. 1 shows a diamond film grown on a silicon substrate by microwave plasma CVD using the diamond growth method of the present invention, where (a) shows a Raman spectrum and (b) shows an image obtained by observing the surface of the diamond film with an optical microscope. FIG. 1 shows a diamond film obtained by growing diamond on a silicon substrate by microwave plasma CVD using the diamond growth method of the present invention, and then growing additional diamond by hot filament CVD, where (a) shows a Raman spectrum, and (b) shows an image obtained by observing the surface of the diamond film with an optical microscope.

As mentioned above, there was a demand for a diamond growth method and diamond growth apparatus capable of growing high-quality, large-diameter diamonds even with plasma CVD using higher-order mode microwaves.

As a result of intensive research into the above-mentioned problems, the inventors have discovered that a diamond growth method including a growth step of growing diamond on a substrate by microwave plasma CVD, characterized in that in the growth step, the microwaves used during diamond growth are in a higher mode, and the substrate is heated while the diamond is growing in the higher mode, thereby controlling the temperature of the substrate, and have completed the present invention.
Furthermore, as a result of intensive research by the inventors into the above-mentioned problems, they have found that a diamond growth apparatus comprising a reaction vessel in which a substrate is stored and into which diamond raw material gas is introduced, and a waveguide connected to the reaction vessel for introducing microwaves into the reaction vessel, in which plasma is generated in the reaction vessel by the microwaves introduced from the waveguide, and the raw material gas is decomposed and activated by the generated plasma to grow diamond on the substrate by CVD, the diamond growth apparatus comprising a mode setting mechanism for changing the microwaves during diamond growth to a higher mode, and a heating control mechanism for heating the substrate while diamond is being grown in the higher mode to control the temperature of the substrate, makes it possible to grow high quality, large diameter diamond even by plasma CVD using microwaves in a higher mode, and have completed the present invention.

The present invention will be described in detail below, but the present invention is not limited thereto.
First, the structure of a diamond substrate 100 manufactured by the diamond growth method of the present invention will be described with reference to FIG.
As shown in FIG. 1, a diamond substrate 100 includes a substrate 2 and a diamond film 13 .
The substrate 2 is a member that serves as a base for growing the diamond film 13. A specific material for the substrate 2 may be any material that allows the diamond film 13 to be grown on its surface and that is not subject to unintended alteration due to the temperature and atmosphere during growth, and may be, for example, silicon single crystal.
The shape of the substrate 2 is generally a disk shape called a wafer, and its diameter (also called aperture) is equal to or greater than the diameter of the diamond film 13 to be grown. The thickness of the substrate 2 is such that warping or cracking does not occur during the growth of the diamond film 13.
The diamond film 13 is a diamond film formed on the substrate 2. Although a specific film structure may be polycrystalline diamond, single crystal diamond is suitable for forming a semiconductor device. The dimensions of the diamond film 13 are such that the diameter is equal to or smaller than the diameter of the substrate 2. The lower limit of the thickness of the diamond film 13 is a thickness that is not lost by etching or polishing when forming the device, and the upper limit of the thickness is preferably a thickness that does not result in a wasted portion that is not used when forming the device, for example.

Next, the schematic configuration of the diamond growth apparatus 11 of the present invention will be described with reference to FIG.
The diamond growth apparatus 11 shown in FIG. 2 is a microwave plasma CVD apparatus that generates plasma in a reaction vessel 1 by microwaves, decomposes and activates a raw material gas with the generated plasma, and grows diamond on a substrate 2 by CVD.

Specifically, as shown in FIG. 2, the diamond growth apparatus 11 comprises a reaction vessel 1 , a source gas introduction tube 6 , a microwave introduction tube 4 , a microwave generator 5 , and a substrate heating stage 3 .
A reaction vessel 1 is a vessel in which diamond growth takes place, in which a substrate 2 is housed, and into which diamond raw material gas is introduced. The specific structure and materials of the reaction vessel 1 can be appropriately selected as long as it has a size and shape that can house the substrate 2 and can withstand the temperature and pressure during diamond growth.
The raw material gas introduction pipe 6 is a gas pipe that introduces raw material gas, which is a compound containing the elements that are the raw materials for diamond, and a carrier gas that is mixed with the raw material gas to diffuse the raw material gas evenly inside the vessel, into the reaction vessel 1, and has one end connected to the reaction vessel 1 and the other end connected to a gas cylinder (not shown) in which the raw material gas and carrier gas are sealed.

The microwave introduction tube 4 is a waveguide that introduces microwaves into the reaction vessel 1, and is connected to the reaction vessel 1. The specific dimensions and shape of the microwave introduction tube 4 can be appropriately selected as long as it has a structure that can introduce microwaves of a desired mode into the reaction vessel 1.
The microwave generating device 5 is a device that generates microwaves, and an example of such a device is a magnetron.
The microwave introduction tube 4 and the microwave generator 5 function as a mode setting mechanism for setting the microwaves during diamond growth to a higher mode. The microwave mode can be adjusted by, for example, the dimensions and shape of the microwave introduction tube 4.

Here, the reason why higher mode microwaves are used in the present invention will be explained.
The microwave mode indicates the length of the microwave resonating in the reaction vessel 1. For example, the microwave indicated as "TM10 mode" in FIG. 3 has a length of 1/2 wavelength. The state in which the microwave resonates at 1/2 wavelength is called "low mode". In the low mode, when the microwave frequency is 2.45 GHz, which is common for CVD, the microwave length L1 is about 12 cm, and the range in which diamond can be formed corresponds to the length of about 1/2 wavelength. However, when plasma is generated with the waveform of FIG. 3, a large distribution difference occurs in the plasma intensity at the antinode and the node of the wave, so that only a part of the wave can actually be used for the growth of diamond, and it is about 1/2 (6 cm) at most, and in reality, it is about 1/4. Therefore, the diameter of the diamond that can be grown in the low mode is about 2 inches (5.05 cm) at most.

On the other hand, the microwaves labeled "TM20 mode" in FIG. 3 have a length of one wavelength, and those labeled "TM40 mode" have a length of two wavelengths. Such a state in which the microwaves resonate at a length of one wavelength or more is called a "higher mode". In the higher mode, the length of the microwaves is longer than in the lower mode, so the area of the plasma generated is larger and the diameter of the diamonds grown is larger. For example, in the "TM20 mode", when the microwave frequency is 2.45 GHz, the length L2 of the microwaves is about 24 cm, and the length of the part that can actually be used to grow diamonds is about 12 cm, so the diameter of the diamonds grown is a maximum of 4 inches (10.2 cm). In the "TM40 mode", when the microwave frequency is 2.45 GHz, the length L3 of the microwaves is about 48 cm, and the length of the part that can actually be used to grow diamonds is about 24 cm, so the diameter of the diamonds grown is a maximum of 8 inches (20.3 cm).

By using microwaves of a higher order mode in this way, diamonds with a large diameter can be grown, which is the reason why microwaves of a higher order mode are used in the present invention.
When using high-order mode microwaves, the diamond growth rate is smaller than that of low-order mode, but the peak energy of the microwaves is relatively small, so the plasma distribution is more uniform than in the low-order mode.
In addition, diamond grows vertically in areas where the plasma density is high, and lateral growth occurs in areas where the plasma density is low, which can contribute to reducing defects in the diamond.
Microwaves include TE waves (orthogonal polarization), which are plane waves whose electric field has only a component perpendicular to the incident surface, and TM waves (parallel polarization), which have a magnetic field whose magnetic field has only a component perpendicular to the incident surface. Although TM waves are shown as an example in Figure 3, the effect of increasing the diameter of the diamond that can be grown can also be obtained by using TE waves.

The substrate heating stage 3 is a base that holds the substrate 2 within the reaction vessel 1, and is also a heating control mechanism that controls the temperature of the substrate 2 by heating the substrate 2 while growing diamond in a higher mode, and is provided within the reaction vessel 1.
Specifically, the substrate heating stage 3 holds the substrate 2 by a chuck mechanism (not shown) provided on the upper surface. The dimensions and shape of the substrate heating stage 3 need only be such that it can hold the substrate 2. When the substrate 2 is a wafer, the substrate heating stage 3 is also disk-shaped and has a diameter larger than that of the substrate 2.
In addition, a heater 7, which is a heating element, is built into the substrate heating stage 3, and when diamond is growing in the higher mode, the heater 7 generates heat and transfers it to the substrate 2 via the substrate heating stage 3 to heat it.

In this way, by heating the substrate 2 with the heating control mechanism while growing diamond in the higher mode, and absorbing temperature unevenness within the surface of the substrate 2, diamond can be grown more uniformly on the substrate 2 than in the case where the substrate 2 is not heated while growing diamond, and high-quality diamond can be grown.

The substrate heating stage 3 serving as a heating control mechanism is preferably a mechanism capable of individually controlling the temperature of the substrate 2 at each position in the substrate 2 .
An example of such a mechanism is a mechanism in which multiple heaters 7 are built into the substrate heating stage 3 in a concentric manner relative to the center of the substrate mounting surface of the substrate heating stage 3 when viewed in a plane, and the temperature settings of the multiple heaters 7 are individually adjusted to individually adjust the temperature according to the radial position of the substrate heating stage 3.
If the substrate heating stage 3 can control the temperature individually according to the position within the substrate 2, the heating temperature can be increased in low-temperature parts of the substrate 2 and decreased in high-temperature parts of the substrate 2, thereby absorbing temperature variations and making the temperature within the substrate 2 uniform. This allows the temperature of the substrate 2 to be controlled more precisely, and allows a higher quality diamond to be grown.

The heater 7 may be a known heating device such as a resistance heating element, a high frequency heater, a lamp, etc., so long as it has a structure capable of heating the substrate 2 to a desired temperature via the substrate heating stage 3.
The temperature distribution of the substrate 2 may be measured, for example, by a thermocouple mounted on a chuck supporting the substrate 2. The thermocouples are preferably mounted at least in two locations, namely, at the center of the substrate 2 and within 140 mm of the outer periphery of the substrate 2 in a plan view, with the substrate 2 mounted.
The above is an explanation of the configuration of the diamond growth apparatus 11 of the present invention.

Next, the diamond growth method of the present invention will be described with reference to FIGS.
First, diamond is grown on a substrate by microwave plasma CVD (S1 in FIG. 4, growth step).

Specifically, first, the door (not shown) of the reaction vessel 1 of the diamond growth apparatus 11 shown in FIG. 2 is opened, the substrate 2 is placed in the reaction vessel 1, and the substrate 2 is mounted on the substrate heating stage 3, and the door is closed. At this time, a diamond substrate or the like may be used as the substrate 2, but if a silicon single crystal substrate is used, diamond can be grown on an inexpensive substrate. In addition, when a silicon single crystal substrate is used as the substrate, a process called scratch processing is performed in which the surface of the substrate 2 is roughened in advance to introduce damage and become the nucleus of growth. Next, the reaction vessel 1 is evacuated to reduce the pressure inside the reaction vessel 1, and then the raw material gas and carrier gas are introduced into the reaction vessel 1 through the raw material gas introduction pipe 6. When growing diamond, the raw material gas is, for example, methane gas, and the carrier gas is, for example, hydrogen gas.
Next, the microwave generator 5 is operated to generate microwaves, which are then irradiated to the reaction vessel 1 via the microwave introduction tube 4 .
The irradiated microwaves resonate within the reaction vessel 1, and a microwave plasma is formed so as to cover the upper part of the substrate 2. The formed microwave plasma decomposes and activates a source gas, for example, methane, and grows diamond on the substrate 2 by CVD.

At this time, the microwaves during the growth of diamond are set to a higher order mode, and while the diamond is growing in the higher order mode, the heater 7 of the substrate heating stage 3 is operated to heat the substrate 2, thereby controlling the temperature of the substrate 2.
A specific microwave mode is selected so that the length of the microwave is equal to or greater than the diameter of the diamond to be grown. The heating temperature of the heater 7 may be any temperature that can absorb temperature irregularities to make the temperature distribution of the substrate 2 uniform and does not inhibit the growth of diamond, for example, about 800°C to 1000°C.
It is also preferable that the temperature distribution within the substrate 2 is as uniform as possible, and for example, it is preferable that the in-plane temperature difference is ±10% or less.

Note that the longer the growth time, the thicker the diamond will be, but once the growth time exceeds a certain level, it becomes difficult to grow the diamond evenly, so the growth time is set within a range that allows the diamond to grow evenly.

If the diamond film 13 grown by microwave plasma in S1 is thick enough, it can be used as is in a later process for forming a device, etc., but in order to grow the diamond film 13 even thicker, it is also possible to grow additional diamond on the substrate 2 grown by microwave plasma in S1 using a hot filament diamond growth device (hereinafter referred to as hot filament CVD device 17) using the method shown in Figure 5, rather than growing it only with microwave plasma.

Specifically, the hot filament CVD apparatus 17 comprises a reaction vessel 21 in which the substrate 2 is housed and diamond is grown, a source gas introduction pipe 23 into which a source gas and a carrier gas are introduced, and a filament 25 which is a resistance heating element.
When using the hot filament CVD apparatus 17, methane as the source gas and hydrogen as the carrier gas are introduced into the reaction vessel 21 from the source gas inlet pipe 23, and electricity is passed through a filament 25 such as tungsten installed above the substrate 2 to electrically heat and decompose the source gas, thereby growing diamond on the substrate 2, thereby growing diamond over the entire large-diameter substrate 2 (S2 in FIG. 4, additional growth process).

In this embodiment, by further growing diamond on the substrate by microwave plasma CVD using a hot filament CVD apparatus 17 capable of large diameter growth, it becomes possible to grow even thicker diamond on the large diameter substrate 2.
The above is an explanation of the diamond growth method of the present invention.

The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.
When growing diamond on substrate 2 by microwave plasma CVD, the microwaves during diamond growth were set to a higher order mode, and substrate 2 was heated during diamond growth in the higher order mode, thereby growing diamond while controlling the temperature of substrate 2, and the physical properties and appearance of the grown diamond were evaluated. The specific procedure is as follows.

(Example 1: Diamond growth by microwave plasma CVD)
A boron-doped high-resistance single crystal silicon substrate (resistivity 100 Ω·cm) having a diameter of 200 mm and a surface orientation of (111) was prepared as substrate 2. The surface was ground with a #8000 grindstone to roughen the silicon surface and introduce damage to serve as nuclei for diamond growth.
This substrate 2 was mounted on the substrate heating stage 3 of a diamond growth apparatus 11 shown in Fig. 2 as a TM20 mode microwave plasma growth apparatus, and a 2.45 GHz microwave was introduced into the reaction vessel 1 at 1500 W to form a plasma, and diamond was grown by CVD under the following conditions: _H2 flow rate: 10 SLM, _CH4 concentration: 3%, substrate temperature: 850°C, and pressure in the reaction vessel 1 was 60 Torr (7999.34 Pa). The temperature of the heater 7 of the substrate heating stage 3 was adjusted so that the substrate temperature at this time was within the range of 850°C ± 5°C within the surface.

The grown diamond film 13 was then measured by Raman spectroscopy, and the surface of the diamond film 13 was observed with an optical microscope to evaluate the growth of the diamond. The Raman spectrum obtained by the measurement is shown in Figure 6(a), and the optical microscope image obtained by observation is shown in Figure 6(b).
As shown in Figure 6(a), the Raman spectrum obtained showed a peak indicating single crystal diamond at a wave number of about 1332 cm ^-1 , and no peaks were observed at other wave numbers, so the growth of diamond was confirmed. Also, as shown in Figure 6(b), the optical microscope image showed fine irregularities indicating the deposition of diamond, and it was confirmed that diamond had grown uniformly from the outside.

This shows that it is possible to grow high-quality, large-diameter diamond even using plasma CVD with higher-order mode microwaves.

(Example 2: Diamond growth by microwave plasma CVD and hot filament CVD)
A boron-doped high-resistance single crystal silicon substrate (resistivity 100 Ω·cm) with a diameter of 300 mm and a surface orientation of (111) was prepared as substrate 2. The surface was ground with a #8000 grindstone to roughen the silicon surface and introduce damage to serve as nuclei for diamond growth.
This substrate 2 was mounted on the substrate heating stage 3 of a diamond growth apparatus 11 shown in Fig. 2 as a TM20 mode microwave plasma growth apparatus, and a 2.45 GHz microwave was introduced into the reaction vessel 1 at 1500 W to form a plasma, and diamond was grown by CVD under the following conditions: _H2 flow rate: 10 SLM, _CH4 concentration: 3%, substrate temperature: 850°C, 60 Torr. (7999.34 Pa). The temperature of the heater 7 of the substrate heating stage 3 was adjusted so that the substrate temperature was within the range of 850°C±5°C in the plane.

Next, this substrate 2 was placed in a hot filament CVD apparatus 17 shown in Fig. 5, and diamond was grown for 4 hours under the conditions of filament temperature: 2200°C, _H2 flow rate: 10 SLM, _CH4 concentration: 3%, substrate temperature: 850°C, and 5 Torr (666.612 Pa).
The grown diamond film 13 was then measured by Raman spectroscopy, and the surface of the diamond film 13 was observed with an optical microscope to evaluate the growth of the diamond. The Raman spectrum obtained by the measurement is shown in Figure 7(a), and the image obtained by observation with the optical microscope is shown in Figure 7(b).
As shown in Figure 7(a), the Raman spectrum showed a peak indicating single crystal diamond at a wave number of about 1332 cm ^-1 , and no peaks were observed at other wave numbers, confirming the growth of diamond. Also, as shown in Figure 7(b), the optical microscope image showed uneven shapes indicating the deposition of diamond, and it was confirmed that diamond had grown uniformly from the outside.

This shows that even plasma CVD using higher mode microwaves can grow high-quality, large-diameter diamonds, and that even greater diamond growth can be achieved using hot filament CVD.

The present specification includes the following aspects.
[1]: A diamond growth method including a growth step of growing diamond on a substrate by microwave plasma CVD,
In the growing step,
A method for growing diamond, comprising: setting microwaves in a higher mode during diamond growth; and heating the substrate during diamond growth in the higher mode, thereby controlling the temperature of the substrate.
[2]: In the growth step,
The method for growing diamond according to the above-mentioned [1], characterized in that the temperature of the substrate at each position within the substrate is controlled individually according to the position.
[3]: After the growth step,
The method for growing diamond according to the above [1] or [2], characterized in that an additional growth step is carried out in which a diamond is further grown on the diamond grown on the substrate using a hot filament CVD apparatus.
[4]: A method for growing diamond according to any one of [1] to [3] above, characterized in that a silicon single crystal substrate is used as the substrate.
[5]: A diamond growth apparatus comprising a reaction vessel in which a substrate is stored and into which a diamond raw material gas is introduced, and a waveguide connected to the reaction vessel and for introducing microwaves into the reaction vessel, in which plasma is generated in the reaction vessel by the microwaves introduced from the waveguide, and the raw material gas is decomposed and activated by the generated plasma, thereby growing diamond on the substrate by CVD,
A mode setting mechanism for setting the microwaves to a higher mode during diamond growth;
a heating control mechanism for controlling the temperature of the substrate by heating the substrate while growing diamond in a higher order mode;
A diamond growth apparatus comprising:
[6]: The heating control mechanism includes:
6. The diamond growth apparatus according to claim 5, further comprising a mechanism for controlling the temperature of the substrate at each position individually according to the position within the substrate.

The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included within the technical scope of the present invention.

1... reaction vessel, 2... substrate, 3... substrate heating stage, 4... microwave introduction tube, 5... microwave generator, 6... raw material gas introduction tube, 7... heater, 11... diamond growth device, 13... diamond film, 17... hot filament CVD device, 21... reaction vessel, 23... raw material gas introduction tube, 25... filament, 100... diamond substrate.

Claims (6)

1. A method for growing diamond, comprising the steps of growing diamond on a substrate by microwave plasma CVD,
In the growing step,
A method for growing diamond, comprising: setting microwaves in a higher mode during diamond growth; and heating the substrate during diamond growth in the higher mode, thereby controlling the temperature of the substrate. In the growing step,
2. A method for growing diamond according to claim 1, wherein the temperature of the substrate is controlled individually at each position within the substrate. After the growth step,
2. The method for growing diamond according to claim 1, further comprising the step of growing an additional diamond on the diamond grown on the substrate using a hot filament CVD apparatus. The diamond growth method according to any one of claims 1 to 3, characterized in that a silicon single crystal substrate is used as the substrate. A diamond growth apparatus comprising: a reaction vessel in which a substrate is housed and into which a diamond source gas is introduced; and a waveguide connected to the reaction vessel and for introducing microwaves into the reaction vessel, wherein plasma is generated in the reaction vessel by the microwaves introduced from the waveguide, and the source gas is decomposed and activated by the generated plasma, thereby growing diamond on the substrate by CVD,
A mode setting mechanism for setting the microwaves to a higher mode during diamond growth;
a heating control mechanism for controlling the temperature of the substrate by heating the substrate while growing diamond in a higher order mode;
A diamond growth apparatus comprising: The heating control mechanism includes:
6. A diamond growth apparatus according to claim 5, further comprising a mechanism capable of individually controlling the temperature of said substrate at each position in said substrate depending on the position.

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