JPH0369878B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an apparatus for forming diamonds on a substrate. More specifically, it is a device that activates a mixed gas of hydrocarbon and hydrogen using high-frequency plasma discharge, direct current glow discharge, or microwave, and irradiates the activated gas and base material with a laser to form a thin film of diamond, etc. Regarding.

[Conventional technology]

Traditionally, diamond synthesis methods include (a) high temperature and high pressure method, (b) thermal filament CVD method (CVD: chemical vapor deposition reaction), and (c) plasma CVD.
The law is known.

(b) The high-temperature and high-pressure method is a method that first became possible to synthesize diamonds artificially in the 1950s, and it uses a metal solvent to synthesize diamonds at high temperatures of several thousand degrees and high pressures of several thousand to tens of thousands of atmospheres. It's a method.

(b) The hot filament CVD method is a method in which, for example, a mixed gas of CH ₄ and H ₂ is introduced around a heated tungsten filament to cause a CVD reaction, and the reaction product is deposited on the base material.

(c) The plasma CVD method is a method in which, for example, opposing electrodes are placed in a mixed gas of CH ₄ and H ₂ and a discharge is caused between the electrodes to generate plasma, decompose CH ₄ , etc., and precipitate carbon. It is.

[Problem that the invention seeks to solve]

Conventional diamond synthesis methods as above
The following problems occurred in (a), (b), and (c), respectively. In the high temperature and high pressure method (a), the equipment becomes large and the manufacturing cost becomes high, and thin films cannot be formed. In the hot filament CVD method (b), diamond can be deposited on the base material, but graphite and amorphous carbon are also deposited at the same time, which poses a quality problem. In the plasma CVD method (c), in addition to the same problems as in the case (b) above, there was also a problem with the reaction rate.

[Means for solving problems]

The diamond thin film forming apparatus according to the present invention activates a gas mixture of hydrocarbon and hydrogen by high-frequency plasma discharge, direct current glow discharge, or microwave, and forms diamond by irradiating the activated gas mixture with a laser. In the device,
A container for storing the above-mentioned mixed gas, a conduit for introducing the gas into this container, a conduit for discharging the gas in this container, a window for projecting a laser into this container, and a high-frequency plasma discharge for the above-mentioned mixed gas. or an electrode for forming a DC glow discharge, or a waveguide for guiding microwaves, a cooling device provided on the microwave irradiation surface, and an X-Y provided in the container on which the substrate is placed. A table and a heating device for the base material are provided, and the laser beam is irradiated along the base material, and the surface of the base material is also irradiated with the laser beam intersecting with the laser beam.

[Effect]

In this invention, the base material placed on the X-Y table provided inside the container is linked to the movement of the table.

The mixed gas is activated by introducing hydrocarbon and hydrogen between the electrodes provided in the container and applying high frequency plasma discharge, direct current glow discharge, or microwave.

Furthermore, if the laser is irradiated near or directly to the surface of the base material, the activated mixed gas absorbs the laser and further increases the degree of activation, increasing the concentration of ions or radical particles, and The surface of the base material is also activated, and carbon is deposited on the surface of the base material in a diamond structure.

Here, the degree of activation of the mixed gas is controlled by the ratio of gases mixed, pressure, discharge power, and laser power, and the degree of activation of the substrate surface is determined by the surface temperature of the substrate and the laser power irradiated to the surface. However, in the present invention, the degree of activation of the gas and the degree of activation of the substrate surface can be determined separately depending on the power (output) balance of the two lasers, so the range of selection of deposition conditions is increased. Due to its large size, film properties such as diamond deposition rate, density, and insulation properties can be easily controlled.

In addition, a localized active region of strong gas is formed near the intersection of the laser beams irradiated from two directions, resulting in high-speed diamond precipitation in a very limited area on the surface of the base material. In addition, since the base material surface of the part irradiated with the laser is activated in a certain state, the difference between the base material surface and the initial deposited layer or when deposited layers are overlapped by scanning the X-Y table. The bonding strength between each layer increases, and the graphite content in the diamond precipitated layer decreases, resulting in a high-quality diamond thin film.

Furthermore, by using an X-Y table to scan the intersection of laser beams irradiated from two directions and the laser irradiation area on the substrate surface, a uniform diamond thin film can be obtained with high controllability of the film thickness, and the substrate The heating temperature can also be lower.

〔Example〕

FIGS. 1a and 1b are explanatory diagrams showing an embodiment of an apparatus using a combination of high-frequency plasma or DC glow discharge and laser according to the present invention.

In the figure, a is a plan view, b is a side sectional view,
1 is a container provided with windows 2, 2a, 2b, and 2c for laser transmission; 3 is a mixed gas introduced into this container;
4 and 4a are lasers irradiated to the gas inside the container through the windows 2 and 2a, and 4b is a laser 4a that is provided inside the container 1 and directly irradiated to the base material 8 placed on an X-Y table (not shown). 6 is a power source that applies high frequency or DC power to electrodes 10 and 10a provided oppositely in this container 1, 8 is a base material on which a diamond thin film is formed, and 12 is a CH ₄
A pipe 12a is a pipe through which a mixed gas 3 of hydrocarbon and hydrogen such as + _H2 is introduced, a pipe 12a is a pipe for discharging the mixed gas 3 in the container 1, and an introduced gas 13a is an exhaust gas. Further, the above-mentioned X-Y table is equipped with a device for heating the base material 8.

Next, this operation will be explained. First, the base material 8 on which diamond is to be formed is placed in the container 1, and then the conduit 12 provided in the container 1 is placed.
The inside of the container 1 is evacuated by a vacuum pump (not shown) provided at the tip of the container 1. Subsequently, a mixed gas of hydrocarbon and hydrogen (introduced gas 13) is introduced from the pipe 12.

Subsequently, when the high frequency or direct current power source 6 is turned on, a high frequency plasma discharge or a direct current glow discharge is generated between the electrodes 10 and 10a, and a part of the mixed gas 3 is ionized and becomes a plasma state.

If the laser 4 is further irradiated here, the mixed gas 3
further increases the degree of activation and increases the plasma concentration.

Hydrocarbons that are one of the components of mixed gas 3, e.g.
CH ₄ is decomposed into carbon and hydrogen, some ions or radicals are generated, and carbon is deposited on the base material 8 in the form of diamonds.

FIGS. 2a and 2b are explanatory diagrams of another embodiment of the present invention, that is, an apparatus using both microwave and laser.

In the figure, a is a plan view, b is a side view, 1
13a indicate the same or equivalent parts as in FIG. 2
0 is a microwave generator that irradiates microwaves into the container 1 through a waveguide 21, 22 is a plunger that circulates cooling water, and 24 and 25 are cooling water.

Further, an X-Y table equipped with a device for heating the base material 8 is provided at the bottom of the container 1 in the same manner as that described in the section of FIG.

Next, this operation will be explained. In this invention as well, a base material 8 is provided, and the components of the mixed gas 3 and the method of introduction are exactly the same as in the embodiment shown in FIG. 1 above.

Next, when the microwave generator 20 is started, the microwave is irradiated through the waveguide 21 across the mixed gas 3 of hydrocarbon and hydrogen in the container 1 to the side of the plunger 22, activating the mixed gas 3. to become The excess energy of the microwave irradiated to the plunger is taken away by the cooling water as thermal energy.

If the mixed gas 3 activated by microwave irradiation is further irradiated with the laser 4, the hydrocarbons will be decomposed into carbon and hydrogen, as in the embodiment shown in FIG. This carbon forms a diamond-shaped thin film on the surface of a suitably surface-treated substrate.

If the base material 8 is directly irradiated with the laser 4a, the surface of the base material 8 will also be activated, so that diamond can be formed partially.

When the base material 8 is placed on an X-Y table (not shown) and run, a diamond thin film is formed over a part or the entire surface of the base material 8.

By adjusting the traveling speed of the base material 8, the diamond layer can be distributed with thick and thin portions.
Once a diamond layer is formed in this way, the subsequent laser 4a acts to activate the surface of the diamond crystal while laminating the diamond layer.

Further, according to the device of the present invention, it is easy to adjust the output of the activation means to obtain optimum conditions.

〔Effect of the invention〕

As explained above, this invention activates a mixed gas of hydrocarbon and hydrogen in a container provided with a base material by high frequency, direct current discharge, or microwave, and then activates the mixed gas along with the base material or If the base material is directly irradiated with a laser, the mixed gas can be further activated and a thin diamond film can be formed on a part of the base material.

Furthermore, by moving the substrate using an X-Y table, the diamond can be distributed over part or all of the substrate.

Since the output of the above-mentioned activation means can be adjusted, it is possible to determine optimal conditions by appropriately adjusting it according to the components of the mixed gas. The engineering value of diamond and its thin films is well known.

For example, a diamond thin film formed on a semiconductor substrate is extremely useful because of its excellent thermal conductivity.

[Brief explanation of drawings]

1A and 1B are explanatory diagrams showing one embodiment of the present invention, and FIGS. 2A and 2B are explanatory diagrams showing another embodiment of the present invention. In the figure, 1 is a container, 2 is a window, 3 is a mixed gas, 4 and 4a are lasers, 6 is a power source (DC or high frequency), 8 is a base material, 10 is an electrode, 12 is a conduit, 13
13a is an introduction gas, 13a is an exhaust gas, 20 is a microwave generator, 21 is a waveguide, 22 is a plunger,
24 is cooling water. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In an apparatus that activates a gas mixture of hydrocarbon and hydrogen by high-frequency plasma discharge, direct current glow discharge, or microwave, and forms diamond by irradiating the activated gas mixture with a laser,
A container for storing the above-mentioned mixed gas, a conduit for introducing the gas into this container, a conduit for discharging the gas in this container, a window for projecting a laser into this container, and a high-frequency plasma discharge for the above-mentioned mixed gas. or an electrode for forming a DC glow discharge, or a waveguide for guiding microwaves, a cooling device provided on the microwave irradiation surface, and an X-Y provided in the container on which the substrate is placed. A table and a heating device for the base material are provided, and the laser beam is irradiated along the base material and the surface of the base material is also irradiated by intersecting the laser beam. A device for forming diamond thin films.