JP2003092263A - Method of manufacturing silicon carbide thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a silicon carbide thin film without heating a silicon wafer to a temperature higher than 1,000 deg.C by using specific ions at low energy. SOLUTION: In the method of manufacturing the silicon carbide thin film, the silicon wafer is irradiated simultaneously or alternately with ions containing carbon and ions containing silicon at low energy, and a single-crystal silicon carbide thin film is formed on the silicon wafer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a silicon carbide thin film and a silicon carbide thin film.

[0002]

2. Description of the Related Art Next-generation semiconductors are required to be able to be used in extreme environments such as high temperature and high radiation, and to be used for high power devices. A substrate in which a single crystal silicon carbide thin film is formed on a silicon wafer is expected as such a next-generation semiconductor, and development is currently underway.

As a method for forming a single crystal silicon carbide thin film on a silicon wafer, a conventional CVD method (Chemical Vapor Dep
osition Method), MBE method (Molecular Beam Epitaxy Meth
Vapor deposition methods such as od) are adopted. Specifically, 1000 ℃
A gas such as a hydrocarbon and a gas such as silane are supplied onto a silicon wafer kept at a higher temperature, and a chemical reaction is caused on the silicon wafer to grow a silicon carbide single crystal.

However, in the above method, since it is necessary to raise the temperature to higher than 1000 ° C. in order to grow silicon carbide, defects and dislocations occur near the interface between silicon and silicon carbide. In addition, the distribution of the concentration of the dopant for controlling the electric conductivity of the device is distorted. Since these cause a reduction in quality as an electronic device, the substrate obtained by the above method is difficult to apply as an electronic device.

Further, in order to obtain an electronic device having better characteristics such as heat dissipation characteristics and improvement of thermal conductivity, it is desired to develop a method for producing a thin film containing only a specific isotope, but in practical use. I haven't arrived.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the prior art, and mainly uses a low energy specific ion to bring a silicon wafer to a temperature higher than 1000.degree. It is an object of the present invention to provide a method for producing a silicon carbide thin film without heating.

[0007]

As a result of earnest research, the inventor has found that a high quality single crystal silicon carbide thin film can be formed on a wafer by irradiating a silicon wafer with a specific ion species at low energy. The present invention has been reached.

That is, the present invention provides the following method for manufacturing a silicon carbide thin film and a silicon carbide thin film. 1. A method for producing a silicon carbide thin film, which comprises irradiating a silicon wafer with ions containing carbon and ions containing silicon at low energy simultaneously or alternately to form a single crystal silicon carbide thin film on a silicon wafer. 2. After irradiating the silicon wafer with ions containing carbon at low energy to convert the silicon wafer surface into silicon carbide,
A method for producing a silicon carbide thin film, wherein a single crystal silicon carbide thin film is formed on a silicon wafer by simultaneously or alternately irradiating carbon-containing ions and silicon-containing ions. 3. 3. The method for producing a silicon carbide thin film as described in 1 or 2 above, wherein the silicon wafer is kept at 300 to 1000 ° C. and irradiated with carbon-containing ions and / or silicon-containing ions. 4. 3. The method for producing a silicon carbide thin film as described in 1 or 2 above, wherein the energy of carbon-containing ions and / or silicon-containing ions is 1 to 500 eV. 5. 3. The method for producing a silicon carbide thin film as described in 1 or 2 above, wherein the amount of current of carbon-containing ions and / or silicon-containing ions is 0.1 μA / cm ^{2 to} 10 mA / cm ² . 6. 3. The method for producing a silicon carbide thin film as described in 1 or 2 above, wherein the carbon-containing ions are mass-separated carbon-containing ions. 7. 3. The method for producing a silicon carbide thin film as described in 1 or 2 above, wherein the ions containing silicon are ions containing silicon separated by mass. 8. 7. The method for producing a silicon carbide thin film as described in 6 above, wherein the carbon contained in the mass-separated carbon-containing ions is only carbon having a mass number of 12 or carbon having a mass number of 13. 9. 8. The method for producing a silicon carbide thin film as described in 7 above, wherein the silicon contained in the mass-separated ions containing silicon is only silicon having a mass number of 28, only silicon having a mass number of 29, or only silicon having a mass number of 30. 10. A silicon carbide thin film containing isotope-separated carbon. 11. A silicon carbide thin film containing isotope-separated silicon. 12. 11. The silicon carbide thin film as described in 10 above, wherein the isotope-separated carbon is a carbon having a mass number of 12 or a mass number of 13. 13. Isotopically separated silicon has a mass number of 28 and a mass number of 2
12. The silicon carbide thin film as described in 11 above, which is 9 or has a mass number of 30. 14. 14. The silicon carbide thin film as described in any one of 10 to 13 above, which has a thickness of 1 nm to 100 μm.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a method for producing a silicon carbide thin film in which a surface of a silicon wafer is simultaneously or alternately irradiated with ions containing carbon and ions containing silicon to form a single crystal silicon carbide thin film on the silicon wafer. According to the method.

Includes carbon for irradiating the surface of a silicon wafer
The ion is not particularly limited, and C_nH_m ^{x +}, C_nH_m ^-Charring
Hydrogen ion (n is about 1 to 100 (preferably about 1 to 20))
Represents any integer within the range of, m is from 1 to
Represents any integer represented by (2n + 2), x is 1 to 10
0 (preferably 1-5, more preferably 1-2)
Denotes any integer within the range); C⁺; C^-;
C₂ ^-And the like. As hydrocarbon ion
More specifically, CH⁺, CH₂ ⁺, CH₃ ⁺, CH_Four ⁺, C
₂H⁺, C₂H₂ ⁺, C₂H₃ ⁺, C₂H_Four ⁺, C₂H_Five ⁺, C₂H₆ ⁺For example
Wear. Among these, CH₃ ⁺, C⁺, C^-, C₂ ^-And so on
Good The carbon-containing ions may be used alone.
Or two or more kinds may be used in combination. Ion quality including carbon
The amount is not particularly limited, but is usually about 12 to 100, and is preferable.
It is about 12 to 80.

Ions containing silicon for irradiating the surface of a silicon wafer are not particularly limited, and examples thereof include silane-based ions such as SiH ₄ ⁺ ; Si ⁺ ; Si ⁻ ; Si ₂ ⁻ . Of these, SiH ₄ ⁺ ; Si ⁺ ; Si ⁻ are preferable. The ions containing silicon may be used alone or in combination of two or more. The mass of the ion containing silicon is not particularly limited, but is usually about 28 to 100, preferably about 28 to 80.

A silicon wafer is irradiated with such carbon-containing ions and silicon-containing ions simultaneously or alternately. Each ion may be an ion beam if necessary. The order of irradiating the ions is not particularly limited, but preferably, first, only the ions containing carbon are irradiated on the silicon wafer to convert the surface of the silicon wafer into silicon carbide.

The amount of ion irradiation to the silicon wafer per time is not particularly limited. The irradiation dose is based on the reflection high-energy electron diffraction method (RHEED).
It can be set appropriately by monitoring with ffraction). For example, when a silicon wafer is irradiated with only ions containing carbon, the ions may be irradiated until the diffraction pattern obtained by RHEED changes from a silicon pattern to a silicon carbide crystal pattern. When the silicon carbide thin film is irradiated with ions containing silicon, the diffraction image obtained by RHEED changes from a pattern of only the silicon carbide crystal to an image in which the pattern of the silicon carbide crystal and the pattern of the silicon crystal overlap. Irradiation with ions is sufficient. When the substrate thus obtained is further irradiated with carbon-containing ions, the irradiation is performed until the silicon crystal pattern gradually disappears from the above-mentioned overlapping pattern and only the silicon carbide crystal pattern is formed. Good. On the other hand, when the silicon carbide thin film is irradiated with the carbon-containing ions, the carbon-containing ions may be irradiated until the silicon carbide crystal pattern disappears in the diffraction image obtained by RHEED. When the obtained substrate is further irradiated with ions containing silicon, the irradiation may be performed until a pattern of silicon carbide crystals appears again. From the viewpoint of easy monitoring by RHEED, it is preferable that the silicon carbide thin film is irradiated with ions containing silicon and then with ions containing carbon. When two types of ions are simultaneously irradiated, the irradiation conditions may be set so that the pattern of the silicon carbide crystal is always observed in RHEED.

The irradiation time per unit area (1 cm ² ) of the silicon wafer can be appropriately set according to the irradiation energy of the ions, the irradiation ion current amount and the like. The irradiation time per unit area of a silicon wafer is
It is usually about 1 second to 60 minutes, preferably about 1 second to 30 minutes, more preferably about 1 second to 20 minutes.

The method for generating carbon-containing ions or silicon-containing ions is not particularly limited, and known methods can be used. As the ion source, for example, Freeman type ion source, Kaufman type ion source, ECR type ion source,
A sputter type ion source etc. can be illustrated.

In the present invention, carbon-containing ions and / or silicon-containing ions are, if necessary,
Mass separation may be performed before irradiating the silicon wafer. By performing mass separation, for example, only ions containing a specific carbon isotope or ions containing a specific silicon isotope can be separated. According to the present invention, a silicon wafer can be selectively irradiated with only desired ions by performing mass separation. Therefore, a silicon carbide thin film containing isotope-separated carbon and / or isotope-separated silicon. Can be manufactured. That is, a silicon carbide thin film containing only carbon having a mass number of 12 or only carbon having a mass number of 13 as a carbon component, or only silicon having a mass number of 28, silicon having a mass number of 29, or silicon having a mass number of 30 as a silicon component. It is possible to manufacture a silicon carbide thin film containing

The silicon carbide thin film containing isotope-separated carbon and / or isotope-separated silicon exhibits high thermal conductivity regardless of the mass number of the isotope. The thermal conductivity of a silicon carbide thin film that is not isotope separated is about 4.9 W / cmK, but, for example, the thermal conductivity of a silicon carbide thin film that isotope separated only for carbon is usually about 6 to 6.8 W / cmK. , Preferably 6.3-
It is about 6.6 W / cmK. The thermal conductivity of a silicon carbide thin film in which only silicon isotope separated is usually about 6.3 to 7 W / cmK, preferably about 6.5 to 6.8 W / cmK. The thermal conductivity of isotope separated silicon carbide thin films for both carbon and silicon is usually 7
It is about 8 W / cmK, preferably about 7.2-7.8 W / cmK.

The silicon wafer used in the method of the present invention is
There is no particular limitation, and a silicon wafer (preferably a single crystal silicon wafer) generally used for manufacturing electronic devices, integrated circuits and the like can be used. The silicon wafer is preferably a silicon single crystal. The thickness of the silicon wafer is not particularly limited, but is usually about 1 μm to 10 mm,
It is preferably about 5 μm to 1 mm. Silicon wafer is
Prior to the ion irradiation, it is preferable to perform a surface treatment for removing an oxide layer on the silicon surface to expose the silicon atomic surface. Such surface treatment method is not particularly limited, cleaning with hydrofluoric acid, under high vacuum (usually 1
A known surface treatment such as heating (usually about 800 to 900 ° C.) at 0-9 to 10-7 Pa) can be applied.

An example of the method for producing a silicon carbide thin film of the present invention will be described more specifically below. First, a silicon wafer is placed in an irradiation vacuum tank or the like, and an ion beam containing carbon and an ion beam containing silicon, which are separately formed, are introduced into the irradiation vacuum tank or the like to irradiate the silicon wafer.

Forming low energy carbon containing ions
The method of applying is not particularly limited. For example, if you are
The method can be illustrated. CH in a discharge box, etc._Four, C₂H₂, C₂H
_Four, C ₂H₆, C₃H₆, C₃H₈Hydrocarbon gas, such as CO, CO₂Such
Gas is introduced and microwave is printed with magnetic field.
The gas is turned into a plasma by adding, and the ion containing carbon is added.
Is generated. Microwave power is typically 10mW-1kW
It is about 0.5 to 1 kW. Microwave circumference
The wave number is about 1 to 3 GHz, preferably about 2 to 2.8 GHz.
It The magnetic field is usually about 0.01-1 Tesla, preferably 0.1-
It is about 1 tesla. To increase the ion generation efficiency,
Even if vapor such as sium and lithium is introduced into the ion source
Good. Ions are drawn from the plasma generated in the ion source.
Irradiation vacuum tank with a silicon wafer installed, etc.
And irradiate the wafer with ions of specified energy.
It

Also in the case of performing mass separation, the method of forming ions containing low energy carbon is not particularly limited, and the following method can be exemplified. In a discharge box, etc., CH ₄ , C ₂ H ₂ , C ₂ H ₄ , C ₂ H ₆ , C ₃ H ₆ , C ₃ H ₈
Introduce a hydrocarbon gas such as CO, a gas such as CO, CO ₂ and apply a microwave together with a magnetic field to turn the gas into a plasma and generate ions containing carbon. The microwave output is usually about 10 mW to 1 kW, preferably 0.5
It is about 1kW. The microwave frequency is about 1 to 3 GHz, preferably about 2 to 2.8 GHz. The magnetic field is usually 0.0
It is about 1 to 1 Tesla, preferably about 0.1 to 1 Tesla.
Vapors such as cesium and lithium may be introduced into the ion source to increase the ion generation efficiency. After the generated ions are extracted from the plasma, the desired ions are mass-separated and introduced into an irradiation vacuum chamber in which a silicon wafer is installed. Before performing the mass separation, the ions may be accelerated to form an ion beam, if necessary. Before irradiation of the silicon wafer, the ion beam may be decelerated to a predetermined energy by applying a reverse electric field as necessary.

The method for forming ions containing low energy silicon is not particularly limited. For example, the following methods can be exemplified. It can be formed by a method of setting a target in an ion source, applying a reverse bias to the target, and ionizing the target by sputtering with a rare gas ion. As rare gas, argon, helium,
Neon, krypton, etc. can be used, of which argon is preferred. Vapors such as cesium and lithium may be further introduced into the ion source in order to increase the ion generation efficiency. A silicon wafer or the like can be used as the target. The magnitude of the bias voltage is not particularly limited, but is usually about 50 kV to 10 kV, preferably about 100 V to 5 kV. Using rare gas plasma generated by introducing a rare gas, plasma containing silicon is generated by a method such as sputtering a target. Ions containing silicon are extracted from the plasma generated in the ion source, introduced into an irradiation vacuum tank or the like, and irradiated to a silicon wafer with predetermined energy.

When mass separation is performed, for example, ions containing silicon can be formed by the following method. Ions generated by the method described above are extracted from the ion source, desired ions are mass-separated, and they are introduced into an irradiation vacuum tank or the like in which a silicon wafer is installed, and the silicon wafer is irradiated with predetermined energy. Before mass separation, it may be accelerated to form an ion beam. Before irradiating the silicon wafer, the ion beam may be decelerated to a predetermined energy by a method of applying a reverse electric field, if necessary.

Ion beads containing ions containing carbon or silicon
Energy when irradiating a silicon wafer as a beam
Is usually about 1 to 500 eV, preferably about 1 to 60 eV,
More preferably, it is about 5 to 40 eV. Which Aeon Bee
However, the amount of current is not particularly limited, but usually 0.1
μA / cm²~ 10 mA / cm²Degree, preferably 1μA / cm²~ 1 mA / c
m ²Degree, more preferably 1 μA / cm²~ 0.5mA / cm²To the extent
It By monitoring the amount of ionic current, carbon or
Or the dose of ions containing silicon can be roughly estimated.
It

In forming the silicon carbide thin film, while irradiating the silicon wafer with ions containing carbon and silicon simultaneously or alternately, the surface shape such as the crystal structure and surface roughness of the surface of the silicon wafer is monitored using RHEED or the like. It is desirable to keep. For example, when the silicon wafer surface is irradiated with carbon-containing ions, it is desirable to monitor the process in which the crystal structure of the silicon wafer surface changes from silicon to silicon carbide by RHEED or the like.

The time for irradiating the silicon wafer with carbon-containing ions or silicon-containing ions can be appropriately set according to the amount of current of the ion beam. For both ion beams, the ion beam current density is 10
At 0 μA / cm ² , the ion beam irradiation time is about 1 to 60 minutes, preferably about 5 to 40 minutes. Alternatively, the irradiation time may be determined by monitoring with RHEED during ion irradiation. For example, when the surface of the silicon wafer is irradiated with ions containing carbon, the ions may be irradiated until the pattern of the silicon wafer disappears and the pattern of silicon carbide crystals appears. If the silicon wafer is excessively irradiated with carbon ions, carbon may be excessive on the silicon carbide surface.

At the time of ion irradiation, the vacuum degree of an irradiation vacuum tank or the like in which a silicon wafer is installed is preferably as high as possible. The degree of vacuum in the irradiation vacuum tank is usually about 10 ^-5 Pa or less, preferably about 10 ^-6 Pa or less.

The temperature of the silicon wafer during ion irradiation is
Usually, it is about 300 to 1000 ° C, preferably about 500 to 700 ° C, more preferably about 600 to 700 ° C.

When the silicon carbide thin film is doped with a doping agent as needed, a method known in the art can be used. For example, a method of introducing a gas containing a dopant, a vapor of an element to be doped, and the like, together with ions containing carbon and / or silicon, to an irradiation vacuum tank in which a silicon wafer is installed and performing irradiation with an ion beam can be adopted. More specifically, when doping with N or the like, N-containing gas (for example, N ₂ , NH ₃ etc.)
It is possible to adopt a method of introducing the light into an irradiation vacuum tank. Ga,
When doping Al, B, etc., a method of introducing a gas containing these elements (for example, hydride such as diborane) to an irradiation vacuum tank; using a high temperature cell such as Knudsen cell, A method can be used in which elemental species (Ga, Al, etc.) are made to flow out as vapor and are introduced into an irradiation vacuum chamber.

The method for mass separation is not particularly limited,
A known method can be applied. For example, electric field type;
Magnetic field type such as sector magnet and Wien filter; quadrupole type, multipole electric field type such as multipole mass filter; time of flight (TOF); ion cyclotron resonance type (EC
R); magnetic field type double convergence type (type in which an analysis unit is configured by a combination of a magnetic field and an electric field) can be exemplified, and an electric field type,
A magnetic field type and a quadrupole type are preferable.

The silicon carbide thin film obtained by the manufacturing method of the present invention is a silicon carbide thin film obtained by coating a silicon wafer with single crystal silicon carbide. The silicon carbide thin film obtained by the manufacturing method of the present invention may include a single crystal silicon carbide layer obtained by converting the silicon wafer surface into silicon carbide.

The silicon carbide thin film obtained by the method of the present invention is a single crystal. Infrared absorption spectrum of a silicon carbide thin film, the full width at half maximum 40 to 60 cm ^-1 degree to about 790～810Cm ^-1, preferably shows a peak of about 30 to 50 cm ^-1. Furthermore, the reflected high-energy electron diffraction image shows a spot shape. The diffraction image obtained by RHEED corresponds to that of single crystal silicon carbide.
Further, in the single crystal silicon carbide thin film obtained by the method of the present invention, the crystal axes of the silicon wafer are aligned with each other. That is, the silicon carbide thin film is epitaxially grown on the silicon wafer. When the silicon carbide single crystal is epitaxially grown, the RHEED diffraction image of the obtained silicon carbide thin film becomes a spot shape and shows a silicon carbide pattern. Alternatively, RHEED the silicon carbide thin film during manufacturing.
It is also possible to determine whether the obtained silicon carbide thin film is a single crystal by monitoring with.

The smoothness of the silicon carbide thin film is not particularly limited as long as the spot shape is observed in the RHEED of the thin film, but the maximum height is usually about 5Å or less, preferably about 3Å.
Below, it is more preferably about 0.1 to 3Å.

The thickness of the single crystal silicon carbide thin film obtained by the manufacturing method of the present invention is not particularly limited. The lower limit of the thickness of the single crystal silicon carbide thin film is usually about 1 nm, preferably 15 n
It is about m. The upper limit of the thickness of the single crystal silicon carbide thin film is
Usually, it is about 100 μm, preferably about 50 μm, more preferably about 10 μm.

The silicon carbide thin film obtained by the manufacturing method of the present invention is not particularly limited as long as it is a single crystal, and preferably has a 3C type cubic close-packed structure.

The silicon carbide thin film may contain N, Al, G as necessary.
It may contain a doping agent such as a or B. The dope amount is
Although it can be appropriately set depending on the type of the doping agent, it is usually about 10 ¹³ to 10 ²⁰ cm ^-3 , preferably 10 ¹⁴ to 10 ¹⁶ cm.
^{-It is} about ^-3 .

[0037]

Industrial Applicability It is desirable that the electronic device manufacturing process be performed at the lowest possible temperature. According to the present invention, it becomes possible to form a high quality single crystal silicon carbide thin film on a silicon substrate at a lower temperature than the conventional manufacturing method.

According to the method of the present invention, a high quality single crystal silicon carbide thin film can be obtained. The obtained single crystal silicon carbide thin film shows a diffraction image including a spot shape in RHEED. The single crystal silicon carbide thin film produced under the preferable conditions exhibits RHEED including a streak shape. Also,
The obtained single crystal silicon carbide thin film has the following spectrum:
790～810Cm ^-1 to a peak, full width at half maximum of the peak is usually about 40~60cm ^-1.

In the production method of the present invention, when mass separation is performed and the ions containing only a specific isotope are irradiated,
A silicon carbide thin film containing only a specific isotope can be manufactured. The silicon carbide thin film containing only a specific isotope has more excellent properties such as thermal conductivity.

[0040]

EXAMPLES Examples of the present invention will be given below together with comparative examples.
The present invention will be described more specifically. The present invention is not limited to the examples below.

Example 1 (100) After the surface of the silicon wafer was washed with hydrofluoric acid to remove the surface oxide layer, the silicon wafer was placed in an irradiation vacuum chamber, and the inside of the vacuum chamber was 8 × 10 ^{−. It was set to 8} Pa or less. After that, the temperature of the silicon wafer was raised to about 900 ° C. for several seconds to clean the surface of the silicon wafer and expose the silicon atomic surface. It was confirmed by observing with RHEED that the silicon surface was cleaned. That is, as a result of observation with RHEED, a (2 × 1) surface superstructure was formed.

On the other hand, carbon-containing ions used for ion beam irradiation were generated as follows. CH ₄ gas, which serves as an ion source, was introduced into the BN discharge box inside the ECR type ion source. A magnetic field of 0.1 Tesla is applied to this BN discharge box, a microwave of about 700 W and a frequency of 2.54 GHz is introduced, the gas in the discharge box is turned into plasma, and it is composed of hydrocarbon ions such as C ⁺ and CH ₃ ^+. Plasma was generated. After extracting the ions from such plasma, the ions containing carbon were introduced into an irradiation vacuum chamber. The obtained carbon-containing ions (ion energy: 50 eV) were irradiated onto a silicon wafer placed in an irradiation vacuum chamber. The irradiation conditions will be described later.

Silicon ions used for ion beam irradiation were generated as follows. A disk made of silicon with a diameter of about 25 mm was fixed to a target holder installed in the sputter ion source. Ar was introduced into the ion source as a discharge gas for target sputtering. this
In order to ionize Ar, thermoelectrons were generated from a tungsten filament placed across the target, and a voltage of about 50 V was applied between the target and the wall surface of the ion source. A bias voltage of -500 V was applied to the target to accelerate ionized Ar, and a silicon target was sputtered to generate silicon plasma. Plasma composed of silicon ions of various masses was extracted from the ion source and led to the irradiation vacuum chamber. The silicon ions (ion energy: 50 eV) thus obtained were irradiated onto a silicon wafer placed in an irradiation vacuum chamber. The irradiation conditions will be described later.

The cleaned silicon wafer was kept at 700 ° C., and the silicon wafer was first irradiated with the above-mentioned carbon-containing ions. The ion current amount was 20 μA / cm ² , and the ion energy was 50 eV. The degree of vacuum in the vacuum chamber at that time was about 10 ^-6 Pa. The irradiated ions containing carbon reacted with Si on the surface of the silicon wafer, and the crystal structure of the surface of the silicon wafer changed from silicon to single crystal silicon carbide. When RHEED monitoring was performed during irradiation of ions containing carbon, the pattern of the silicon wafer disappeared and the pattern of silicon carbide crystals appeared in RHEED, so the ion irradiation was stopped. The irradiation time per cm ^{2 of the} silicon wafer was about 1 minute.

A streak shape was observed in the RHEED of the substrate surface during and after the ion beam irradiation, confirming that silicon carbide was epitaxially formed on the silicon wafer.

After the surface of the silicon wafer was siliconized by the irradiation of the ion beam containing carbon, the irradiation of the silicon ion beam of 50 eV generated as described above and the irradiation of the carbon ion beam of 50 eV were carried out for 1 minute. Alternate irradiation was performed alternately to grow a silicon carbide epitaxial thin film. The amount of ion current of silicon ion and that of carbon ion were each about ²⁰ μA / cm ² . The degree of vacuum in the irradiation vacuum chamber during ion irradiation was about 10 ⁻⁶ Pa. The substrate temperature during ion irradiation is 7
It was set to 00 ° C. While alternately irradiating the ion beam,
By monitoring the growth process by RHEED, 3C-SiC can be detected by the deposition of silicon atoms and the reaction with carbon atoms.
Was confirmed to have grown epitaxially. The irradiation time of the two types of ion beams was 40 minutes in total.

The obtained epitaxial 3C-SiC (film thickness: about 3
Infrared absorption measurement of (0 nm), 800 cm ^-1
Has a full width at half maximum (peak width at half peak intensity) of approx.
A sharp absorption peak at 50 cm ^-1 was obtained (Fig. 1). The sharper the peak, the higher the crystallinity of the obtained thin film.
From this full width at half maximum value (about 50 cm ^-1 ), it was found that single-crystal silicon carbide having a level of defects and crystallinity at least equivalent to the conventional level was epitaxially grown.

By repeating the above-mentioned ion irradiation operation, a thicker single crystal silicon carbide thin film can be obtained.

Example 2 A silicon wafer having a Si (100) surface was washed with hydrofluoric acid to remove the surface oxide layer, and then the silicon wafer was placed in an irradiation vacuum chamber and the inside of the vacuum chamber was set to 7 × 10 7. The pressure was reduced to ^-8 Pa or less. After that, the temperature of the silicon wafer was raised to about 900 ° C. for several seconds to clean the surface of the silicon wafer and expose the silicon atomic surface. It was confirmed by RHEED observation that the silicon surface was cleaned. That is, as a result of observation with RHEED, a (2 × 1) surface superstructure was formed.

On the other hand, carbon-containing ions used for ion beam irradiation were generated as follows. Ion source gas (CO ₂ ) was introduced into the BN discharge box inside the ECR ion source. A magnetic field of 0.1 Tesla was applied to this BN discharge box, and a microwave of about 800 W and a frequency of 2.54 GHz was introduced to turn the gas in the discharge box into plasma. Ions were extracted from the generated plasma and accelerated to about 20 keV, and then ¹² C ⁺ was selectively separated by mass. Only the mass-separated carbon-containing ions are guided to the irradiation vacuum chamber, and a reverse electric field is applied to decelerate them immediately before the silicon wafer, and the ion energy is 50 eV.
And Ions containing low-energy carbon thus obtained were irradiated onto a silicon wafer placed in an irradiation vacuum chamber. The irradiation conditions will be described later.

Ions containing silicon used for ion beam irradiation were generated as follows. 25 mm diameter in the target holder installed in the sputter ion source
A circular disc made of silicon was fixed. Ar was introduced into the ion source as a discharge gas for target sputtering, and cesium vapor was introduced to increase the ion generation efficiency. A bias voltage of -200 V for sputtering is applied to the target, and a voltage of about 50 V is applied between the target and the ion source, and Ar is ionized by thermionic electrons from the tungsten filament placed across the target, and the silicon target Was sputtered. After negative ions generated as a result of sputtering were accelerated to about 20 keV, only Si ⁻ ions (mass 28) were selectively separated by mass. The ²⁸ Si ^- ions separated by mass are guided to an irradiation vacuum chamber, and a reverse electric field is applied to decelerate them immediately before the silicon wafer, and the ion energy is reduced to 50 e.
V. The low-energy silicon ions thus obtained are irradiated onto a silicon wafer placed in an irradiation vacuum chamber. The irradiation conditions will be described later.

The cleaned silicon wafer was kept at 700 ° C., and the silicon wafer was first irradiated with ions containing carbon. Irradiation was performed with ¹² C ⁺ having an ion current amount of 3 μA / cm ² and an ion energy of 50 eV. The degree of vacuum in the vacuum chamber at that time was about 10 ⁻⁶ Pa. The irradiated carbon ions are
By reacting with Si on the silicon wafer surface, the crystal structure of the silicon wafer surface changed from single crystal silicon to single crystal silicon carbide. When RHEED monitoring was performed during carbon ion irradiation, the pattern of the silicon wafer disappeared and a pattern of silicon carbide crystals appeared in RHEED, so the ion irradiation was stopped. The irradiation time per cm ^{2 of the} silicon wafer was about 10 minutes.

A streak shape was observed in the RHEED of the substrate surface during and after the ion beam irradiation, confirming that silicon carbide was epitaxially formed on the silicon wafer.

After the surface of the silicon wafer was siliconized by irradiation with an ion beam containing carbon, ²⁸ e ^- ion beam of 50 eV and ¹² C of 50 eV generated as described above were used.
⁺ Alternating irradiation with ion beam for 20 minutes, ²⁸ Si and ¹² C
A silicon carbide epitaxial thin film consisting of only was grown. The amount of ion current of silicon ion and that of carbon ion were each about 3 μA / cm ² . The degree of vacuum in the irradiation vacuum chamber during ion irradiation was about 10 ⁻⁶ Pa. The substrate temperature during ion irradiation was 700 ° C. During the alternating ion beam irradiation, by monitoring the growth process by RHEED, the deposition of silicon atoms and the reaction with carbon atoms cause 3C
-It was confirmed that SiC was epitaxially grown.
The irradiation time of the two types of ion beams was 4 hours in total.

The obtained epitaxial 3C-SiC (film thickness: about 3
Infrared absorption measurement of (0 nm), 800 cm ^-1
Has a full width at half maximum (peak width at half peak intensity) of approx.
A sharp absorption peak at 50 cm ^-1 was obtained. The sharper the peak, the higher the crystallinity of the obtained thin film. From this full width at half maximum value (about 50 cm ^-1 ), it was found that single-crystal silicon carbide having a level of defects and crystallinity at least equivalent to the conventional level was epitaxially grown. By repeating the operation of ion irradiation as described above, a single crystal silicon carbide thin film having a larger film thickness can be obtained.

The thermal conductivity of the obtained single crystal silicon carbide thin film was about 7.5 W / cm · K at 300K.

Example 3 A silicon wafer having a Si (100) surface was washed with hydrofluoric acid to remove a surface oxide layer, and then the silicon wafer was placed in an irradiation vacuum chamber, and the inside of the vacuum chamber was set to 7 × 10 7. The pressure was reduced to ^-8 Pa or less. After that, the temperature of the silicon wafer was raised to about 900 ° C. for several seconds to clean the surface of the silicon wafer and expose the silicon atomic surface. It was confirmed by RHEED observation that the silicon surface was cleaned. That is, as a result of observation with RHEED, a (2 × 1) surface superstructure was formed.

On the other hand, it contains carbon used for ion beam irradiation.
The ions were generated as follows. ECR type ion
In the BN discharge box inside the source, the gas (CO₂And C
H_Four) Was introduced. A magnetic field of 0.1 Tesla is applied to this BN discharge box.
Introduces microwave of about 800 W and frequency of 2.54 GHz
Then, the gas in the discharge box was turned into plasma. Generated plastic
From Zuma, C⁺, CH₃ ⁺I draw an ion containing carbon such as
Then, after accelerating to about 20keV, C ⁺Ions (mass number 12) and
And CH₃ ⁺Ions (mass number 15) were separated by mass. Mass separated
The carbon-containing ions to the irradiation vacuum chamber and generate a reverse electric field.
By decelerating, decelerating just before the silicon wafer,
Energy of 50 eV. Thus obtained
Ions containing low energy carbon are installed in the irradiation vacuum chamber
Irradiation was performed on the formed silicon wafer. About irradiation conditions
Will be described later.

Ions containing silicon used for ion beam irradiation were generated as follows. 25 mm diameter in the target holder installed in the sputter ion source
A circular disc made of silicon was fixed. Ar was introduced into the ion source as a discharge gas for target sputtering, and cesium vapor was introduced to increase the ion generation efficiency. A bias voltage of -200 V for sputtering is applied to the target, and a voltage of about 50 V is applied between the target and the ion source, and Ar is ionized by thermionic electrons from the tungsten filament placed across the target, and the silicon target Was sputtered. After negative ions generated as a result of sputtering were accelerated to about 20 keV, Si ⁻ ions (mass 28) were separated by mass. The mass-separated ions containing silicon were introduced into an irradiation vacuum chamber and decelerated immediately before the silicon wafer by applying a reverse electric field, and the ion energy was set to 50 eV. The low-energy silicon ions thus obtained are irradiated onto a silicon wafer placed in an irradiation vacuum chamber. The irradiation conditions will be described later.

The cleaned silicon wafer was kept at 700 ° C., and the silicon wafer was first irradiated with carbon-containing ions. The ions were irradiated with C ⁺ or CH ₃ ⁺ having an ion current amount of 3 μA / cm ² and an ion energy of 50 eV. The degree of vacuum in the vacuum chamber at that time was about 10 ⁻⁶ Pa. The irradiated ions containing carbon reacted with Si on the surface of the silicon wafer, and the crystal structure of the surface of the silicon wafer was changed from single crystal silicon to single crystal silicon carbide. When RHEED monitoring was performed during irradiation of ions containing carbon ions, RHE
In the ED, the pattern of the silicon wafer disappeared and the pattern of the silicon carbide crystal appeared, so the ion irradiation was stopped.
The irradiation time per cm ^{2 of the} silicon wafer was about 10 minutes.

A streak shape was observed in the RHEED of the substrate surface during and after the ion beam irradiation, confirming that silicon carbide was epitaxially formed on the silicon wafer.

After the surface of the silicon wafer was siliconized by the irradiation of the ion beam containing carbon, the irradiation of the 50 eV silicon ion beam generated above and the irradiation of the carbon ion beam of 50 eV were alternately performed for 20 minutes. Then, a silicon carbide epitaxial thin film was grown. The amount of ion current of silicon ion and that of carbon ion were each about 3 μA / cm ² . The degree of vacuum in the irradiation vacuum chamber during ion irradiation was about 10 ⁻⁶ Pa. The substrate temperature during ion irradiation was 700 ° C. During the alternating ion beam irradiation, the growth process was monitored by RHEED, and it was confirmed that 3C-SiC was epitaxially grown due to the deposition of silicon atoms and the reaction with carbon atoms (Fig. 2). The irradiation time of the two types of ion beams was 4 hours in total.

The obtained epitaxial 3C-SiC (film thickness: about 3
Infrared absorption measurement of (0 nm), 800 cm ^-1
Has a full width at half maximum (peak width at half peak intensity) of approx.
A sharp absorption peak at 50 cm ^-1 was obtained (Fig. 3). The sharper the peak, the higher the crystallinity of the obtained thin film. From this full width at half maximum value (about 50 cm ^-1 ), it was found that single-crystal silicon carbide having a level of defects and crystallinity at least equivalent to the conventional level was epitaxially grown.

The thermal conductivity of the obtained single crystal silicon carbide thin film was about 7.7 W / cm · K at 300K.

By repeating the above-mentioned ion irradiation operation, a thicker single crystal silicon carbide thin film can be obtained.

[Brief description of drawings]

FIG. 1 shows an infrared absorption spectrum of the single crystal silicon carbide thin film obtained in Example 1.

FIG. 2 shows a RHEED diffraction image of the single crystal silicon carbide thin film obtained in Example 3. The diffraction image of FIG. 2 shows a spot shape.

FIG. 3 shows an infrared absorption spectrum of the single crystal silicon carbide thin film obtained in Example 3.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Jun Kinomura             1-83-1 Midorigaoka, Ikeda, Osaka Prefecture             AIST Kansai Center (72) Inventor Yuji Horino             1-83-1 Midorigaoka, Ikeda, Osaka Prefecture             AIST Kansai Center F-term (reference) 4G077 AA03 BE08 DA20 EA02 EJ03                       HA06                 4K029 AA06 BA56 BD01 CA10 EA01                       EA08 FA04                 5F103 AA06 BB09 BB14 BB55 DD17                       GG01 HH03 KK03 KK10 NN01                       PP02

Claims (14)

[Claims] 1. A method for producing a silicon carbide thin film, which comprises irradiating a silicon wafer with carbon-containing ions and silicon-containing ions at low energy simultaneously or alternately to form a single-crystal silicon carbide thin film on the silicon wafer. 2. A silicon wafer is irradiated with carbon-containing ions at a low energy to convert the surface of the silicon wafer into silicon carbide, and then carbon-containing ions and silicon-containing ions are simultaneously or alternately irradiated onto the silicon wafer. A method for manufacturing a silicon carbide thin film, which comprises forming a single crystal silicon carbide thin film on a substrate. 3. The method for producing a silicon carbide thin film according to claim 1, wherein the silicon wafer is kept at 300 to 1000 ° C. and the carbon-containing ions and / or the silicon-containing ions are irradiated. 4. The method for producing a silicon carbide thin film according to claim 1, wherein the energy of carbon-containing ions and / or silicon-containing ions is 1 to 500 eV. 5. The method for producing a silicon carbide thin film according to claim 1, wherein the amount of current of carbon-containing ions and / or silicon-containing ions is 0.1 μA / cm ^{2 to} 10 mA / cm ² . 6. The method for producing a silicon carbide thin film according to claim 1, wherein the carbon-containing ions are mass-separated carbon-containing ions. 7. The method for producing a silicon carbide thin film according to claim 1, wherein the ions containing silicon are ions containing silicon separated by mass. 8. The method for producing a silicon carbide thin film according to claim 6, wherein the carbon contained in the mass-separated carbon-containing ions is only carbon having a mass number of 12 or carbon having a mass number of 13. 9. The silicon carbide thin film according to claim 7, wherein the silicon contained in the mass-separated ions containing silicon is only silicon having a mass number of 28, only silicon having a mass number of 29, or only silicon having a mass number of 30. A method of manufacturing. 10. A silicon carbide thin film containing isotope-separated carbon. 11. A silicon carbide thin film containing isotope-separated silicon. 12. The silicon carbide thin film according to claim 10, wherein the isotope-separated carbon is a carbon having a mass number of 12 or a mass number of 13. 13. Isotopically separated silicon has a mass number of 28,
The silicon carbide thin film according to claim 11, which is silicon having a mass number of 29 or a mass number of 30. 14. A thickness of 1 nm to 100 μm.
The silicon carbide thin film according to any one of 1 to 13.