JPH04338197A - Synthesizing method for diamond - Google Patents

Abstract

PURPOSE:To uniform a formed film and also to enhance the film forming speed by synthesizing diamond while reactive gas and a base plate are especially irradiated with ultraviolet rays in a state wherein a mirror field is formed in relation to a method for synthesizing diamond. CONSTITUTION:In a method for synthesizing diamond, a gaseous mixture 2 incorporating at least a gaseous carbon-contg. compd. and gaseous oxygen is supplied into a plasma chamber 4. Diamond is synthesized on the surface 11a of a base plate 11 provided to the inside of a reaction chamber 1 by a plasma CVD method. While the gaseous mixture 2 is irradiated with a first ultraviolet rays 8a in a state wherein mirror fields due to the magnetic fields described below are formed, this gaseous mixture 2 is passed through microwave plasma. The magnetic fields are formed of a plurality of magnetic field generating means 5 provided to the outer circumferential position of the plasma chamber 4. Furthermore while the passed gaseous mixture 2 and the surface 11a of the base plate are irradiated with a second ultraviolet rays 6a, synthesis of diamond is performed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for synthesizing diamond, and in particular, by performing synthesis while forming a mirror magnetic field and irradiating a reactive gas and a substrate with ultraviolet rays, the film can be uniformly formed. Concerning novel improvements to increase deposition speed.

0002

BACKGROUND OF THE INVENTION There are various methods of synthesizing this type of diamond that have been used in the past.
Examples include methods disclosed in Japanese Patent Application Laid-open No. 94 and Japanese Unexamined Patent Publication No. 63-107899. That is, in JP-A-62-13894, a mixed gas of hydrocarbon and hydrogen is activated by thermionic radiation and heated to 600°C.
In the diamond synthesis method in which diamond is precipitated on the substrate surface heated to 1200°C or less, the mixed gas, the substrate surface, or thermionic emissive material is indispensable, and at least one high-power ultraviolet ray is applied from the outside. This method uses irradiation to synthesize diamond on the surface of the substrate. Furthermore, in Japanese Patent Application Laid-Open No. 63-107899, a thin film forming gas containing a hydrocarbon gas is introduced into a plasma chamber and a reaction chamber, and a magnetic field and microwave power are applied to the gas from the outside. Plasma is generated in a pressure range of 100 pa to 10-2 pa, and diamond is heated in advance by the excited ion species, active species, etc. in the thin film forming gas by the plasma, and is deposited on the surface of the substrate held in the reaction chamber. This method is designed to synthesize.

0003

[Problems to be Solved by the Invention] Conventional diamond synthesis methods were constructed as described above, and therefore had the following problems. That is, JP-A-62-13
In the synthesis method disclosed in Publication No. 8394, a mixed gas of hydrocarbon and hydrogen is irradiated with ultraviolet rays, but there is currently no practical ultraviolet generator that can activate hydrogen, which plays an important role in the diamond synthesis method. However, it has not been put into practical use. Additionally, attempts have been made to use ultraviolet light generators such as excimer lasers to activate hydrocarbons, but excimer lasers are extremely expensive and currently only nanoseconds (ns, 1
Since it can only emit extremely short pulses (on the order of 0-9 seconds) from several times to several hundred times per second, the cumulative time for irradiating the mixed gas is short, and the activation time due to irradiation that accounts for very little in the reaction time. Therefore, the irradiation effect is small, and the current situation is that even if expensive means are used, almost no effect of ultraviolet irradiation can be obtained.

Furthermore, in the synthesis method disclosed in JP-A-63-107899, diamond was synthesized only by plasma excitation without adding any auxiliary treatment to the reaction gas. When synthesized using a substrate, only 0.5 μm thickness could be obtained in 5 hours,
It has been impossible to shorten this synthesis time.

The present invention has been made to solve the above-mentioned problems, and in particular, it is possible to use an ultraviolet generator that can provide continuous light at low cost, such as a low-pressure mercury lamp, in a state where a mirror magnetic field is formed. The reaction gas is a mixed gas of a carbon-containing compound containing oxygen, which can be activated using UV light, and plasma excitation is combined with activation of the substrate surface by ultraviolet irradiation and activation by thermionic radiation to the substrate. It is an object of the present invention to provide a method for synthesizing diamond that makes the film uniform and increases the film formation rate.

[0006]

[Means for Solving the Problems] A diamond synthesis method according to the present invention supplies a mixed gas containing at least a carbon-containing compound gas and an oxygen gas to a plasma chamber, and
In a diamond synthesis method in which diamond is synthesized on the surface of a substrate provided in a reaction chamber by method D, a mirror magnetic field is formed by magnetic fields from a plurality of magnetic field generation means provided at an outer circumferential position of the plasma chamber. A method of synthesizing diamond while irradiating the mixed gas with a first ultraviolet ray while passing the mixed gas through a microwave plasma, and further irradiating the mixed gas and the substrate surface after the passage with a second ultraviolet ray. It is.

More specifically, this is a method in which diamond is synthesized while applying a direct current bias potential between the thermionic emitter provided in the reaction chamber and the sample stage.

More specifically, the wavelength of the first ultraviolet rays irradiated when the mixed gas passes through the microwave plasma and the wavelength of the second ultraviolet rays irradiated onto the mixed gas and the substrate surface after passing through the microwave plasma. This is a different method.

[0009]

[Operation] In the method for synthesizing diamond according to the present invention, a mixed gas containing at least carbon-containing compound gas and oxygen gas is supplied to a plasma chamber, and a magnetic field is generated from a plurality of magnetic field generating means provided at the outer circumferential position of the plasma chamber. With a mirror magnetic field formed by the plasma chamber, the mixed gas is passed through the microwave plasma while being irradiated with the first ultraviolet rays emitted from a light source installed in the plasma chamber. , further promotes the excitation of atoms, etc., and also irradiates the second ultraviolet rays even after passing through the plasma to excite the mixed gas that remains unexcited.In addition, the second ultraviolet rays are also applied to the surface of the substrate. Irradiation cleans the surface of the substrate and excites the particles to increase the distance they can travel on the substrate, allowing them to enter open voids on the substrate, resulting in a uniform diamond film being formed quickly. It is formed. Furthermore, the magnetic field distribution is adjusted by the mirror magnetic field, and the plasma density and film thickness are made uniform. In addition, the deposition rate is further increased by thermionic bombardment on the surface of the substrate.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the diamond synthesis method according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a diamond synthesis apparatus applied to the diamond synthesis method according to the present invention, and FIG. 2 is an enlarged view of the main part of FIG. 1.

In FIG. 1, the reference numeral 1 indicates a reaction chamber which is constructed in a sealed state and maintained in a vacuum state through an exhaust means 1A, and a plasma chamber 4 is connected to this reaction chamber 1. The reaction chamber 1 and the plasma chamber 4 are each provided with a gas supply pipe 2A for supplying a mixed gas 2 containing at least a carbon compound gas and an oxygen gas. Note that the mixed gas 2 supplied to the reaction chamber 1 and the mixed gas 2 supplied to the plasma chamber 4 may be of the same type or may be of different types.

The plasma chamber 4 includes a magnetic field generating means 5 consisting of an excitation coil for generating a magnetic field 5a (shown in FIG. 2) in the reaction chamber 1, and a plurality of microwave oscillators 3.
A microwave supply pipe 3B is provided for supplying microwaves 3A from. One end 4a of the plasma chamber 4
A first light source 8 and a first power source 9 are provided at the other end 4b, and each first light source 8 emits a first ultraviolet ray 8a. A second light source 6 is attached to the upper end 1a of the reaction chamber 1, a second power source 7 is connected to the second light source 6, and a second ultraviolet ray 6a is emitted from the second light source 6. There is.

Each of the light sources 6, 8 is composed of, for example, a deuterium lamp, a mercury lamp, a xenon lamp, etc. for emitting ultraviolet rays 6a, 8a. The first ultraviolet light 8a is configured to be irradiated into the plasma created by the mixed gas 2 and the microwave 3A in the plasma chamber 4. Further, the second ultraviolet ray 6a is transmitted to a sample stage 10 located inside the reaction chamber 1.
The surface 11a of the substrate 11 attached to the mixed gas 2
It is configured to be irradiated with.

[0014] The sample stage 1 installed in the reaction chamber 1
A thermionic emitting material 12 is provided at an upper position facing 0, and a power source 14 for heating the thermionic emitting material 12 is connected to the sample stage 10 and the thermionic emitting material 12. A power supply 13 for applying a bias potential is connected. As shown in FIG. 2, a plurality of the magnetic field generating means 5 are arranged on the outer periphery of the reaction chamber 1, and the magnetic fields 5a from each magnetic field generating means 5 collide with each other in the reaction chamber 1, creating a mirror. A magnetic field is formed.

Therefore, using the above-mentioned diamond synthesis apparatus, the mixed gas 2 is supplied to the reaction chamber 1 and the plasma chamber 4, and the light from the first light source 8 of the plasma chamber 4 is emitted while the mirror magnetic field is formed. The first ultraviolet ray 8a is irradiated to the mixed gas 2 while passing through the plasma, further promoting the excitation of molecules, atoms, etc. of the mixed gas 2 by the plasma, and even after passing through the plasma, the second light source of the reaction chamber 1 is used. 6 to excite the remaining unexcited mixed gas 2, and in addition, the surface 11a of the substrate 11 is also irradiated with the second ultraviolet 6a, so that the surface 11a of the substrate 11 is Second
A diamond film (not shown) is formed on the surface 11a of the substrate 11 in the reaction chamber 1 while being cleaned by the ultraviolet rays 6a.

In this case, by irradiating the plasma with the first ultraviolet ray 8a, molecules of the mixed gas 2 in the plasma,
The atoms, etc. are further activated, and by irradiating the second ultraviolet ray 6a even after passing through the plasma, the mixed gas 2 that remains unexcited is also activated, and in addition, the substrate 11
By irradiating the surface 11a with the second ultraviolet ray 6a, the surface 11a is cleaned, and the distance over which the particles can move on the substrate 11 is increased, and the particles enter the open spaces, so that a uniform diamond film can be quickly obtained. be able to. Furthermore, the generation of the mirror magnetic field makes the magnetic field distribution uniform, making the film thickness uniform and the plasma density uniform.

[0017] Furthermore, the film formation rate can be further increased by heating the thermionic emitting material 12 to emit thermionic electrons, and applying a bias potential with the sample stage 10 as positive and the thermionic emitting material 12 as negative. . Since the mixed gas 2 contains oxygen gas, the mixed gas and the substrate 11 can be activated using a commercially available inexpensive ultraviolet light emitting device that can provide continuous light, so that a diamond film can be obtained at a low cost.

[0018]

[Effects of the Invention] Since the diamond synthesis method according to the present invention is constructed as described above, the following effects can be obtained. That is, under a state in which a mirror magnetic field is formed, the mixed gas is passed through a microwave plasma while being irradiated with a first ultraviolet ray, and further, the mixed gas and the substrate surface after passing are irradiated with a second ultraviolet ray. In order to synthesize diamond, the molecules and atoms in the plasma are further activated by ultraviolet rays, and the diamond film can be formed while cleaning the surface of the substrate, which speeds up the adhesion of particles and creates a uniform film. can be formed faster than conventional methods. Moreover, since the means for generating ultraviolet rays may be inexpensive, and a reactive gas containing oxygen gas is used, the film can be formed at a low cost because it can be activated by an inexpensive light generating device.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a diamond synthesis apparatus applied to a diamond synthesis method according to the present invention.

FIG. 2 is an enlarged view showing the main parts of FIG. 1;

[Explanation of symbols]

1 Reaction chamber 2 Mixed gas 4 Plasma chamber 5 Magnetic field generation means 6a Second ultraviolet light 8a First ultraviolet light 10 Sample stage 11　　　　Substrate 11a Surface

Claims (3)

[Claims] 1. A mixed gas (2) containing at least a carbon-containing compound gas and an oxygen gas is supplied into a plasma chamber (4), and a substrate (11) provided in a reaction chamber (1) is heated by a plasma CVD method. In a method for synthesizing diamond in which diamond is synthesized on the surface (11a), a mirror magnetic field is formed by magnetic fields from a plurality of magnetic field generating means (5) provided at an outer peripheral position of the plasma chamber (4). Then, the mixed gas (2) is passed through a microwave plasma while irradiating the mixed gas (2) with a first ultraviolet ray (8a), and the mixed gas (2) and the substrate surface (11a) after passing are ) is irradiated with second ultraviolet light (6a) while diamond synthesis is performed. [Claim 2] Diamond synthesis is performed in a state where a direct current bias potential is applied between the thermionic emitting material (12) provided in the reaction chamber (1) and the sample stage (10). The method of synthesizing diamond according to claim 1, characterized in that: 3. The first ultraviolet ray () irradiated when the mixed gas (2) passes through the microwave plasma.
3. The diamond synthesis method according to claim 1, wherein the wavelength of the second ultraviolet ray (6a) irradiated to the mixed gas (2) and the substrate surface (11a) after passing through is different from the wavelength of the second ultraviolet ray (6a). .