JPH0543792B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention applies microwave electricity and an external magnetic field, uses their interaction, provides a film forming means in the space where the electric field is largest, and forms a film. The present invention relates to a thin film forming apparatus and a forming method.

[Conventional technology]

Conventionally, ECR (Electron Cyclotron Resonance) has been used as a means of forming thin films, and the diverging magnetic field is used to place a substrate at a position ``remote'' from this resonant space, and forms a film there, especially a film with an amorphous structure. There are known ways to do this.

Furthermore, in addition to ECR CVD (chemical vapor deposition), there are several known film forming methods using reactive gases, including thermal CVD,
Heated filament CVD, chemical transport method, 13.56MHz
Plasma CVD methods that use a frequency of , and plasma CVD methods that use only microwaves are known.
In particular, the ECR CVD method pinches active species using a magnetic field to increase the energy, thereby increasing the electron energy and efficiently converting gas into plasma. However, by turning it into plasma, the ECR
Film formation or anisotropic etching is achieved by arranging the substrate in a ``difficult position'' from the space that satisfies the conditions and delivering reactive gas in the form of an ion shower that avoids the plasma state under high energy conditions. I was gone.

[Conventional problems]

However, such film forming methods using showered reactive gases employ either anisotropic etching or deposition process, such as anisotropic etching or film formation with an amorphous structure, depending on the type of gas. .
Therefore, in this case, a coating having an amorphous structure is likely to be formed on the surface to be formed, and it is extremely difficult to form a coating having crystallinity, particularly polycrystalline or single crystal. In addition, by using high energy, it was also impossible to form a film that could activate or react reactive gases for the first time.

[Means to solve the problem]

The present invention attempts to form a film while etching a part of the film, and preferably forms a film having crystallinity in at least a part of the film. For this purpose, a substrate having a surface to be formed is disposed in a region where the electric field strength of microwave power is greatest. Furthermore, electric field/magnetic field interaction is created in that region. For example, ECR
(electron cyclotron resonance). Furthermore, by adjusting the strength of the magnetic field, it becomes possible to form a film that can undergo decomposition or reaction only in this region. For example, i-carbon (diamond or carbon coating with microcrystalline grains)
It is also a high melting point metal or ceramic insulating coating.

That is, the present invention adds the force of a magnetic field to the conventionally known plasma CVD method using microwaves, and further applies the interaction between the electric field of the microwave and the magnetic field, preferably ECR (electron cyclotron resonance).
Conditions or interactions involving Heutzler resonance conditions are used to generate dense, high-energy plasmas over a wide range of pressures. Utilizing the high energy state in the resonance space, it is possible to generate a large amount of activated carbon atoms and form films such as diamond and i-carbon films with excellent reproducibility, uniform thickness, and homogeneous properties. That is. Additionally, since the strength of the applied magnetic field can be changed arbitrarily, it is possible to set ECR conditions not only for electrons but also for specific ions.

Additionally, in addition to the structure of the present invention, after high-density plasma is generated by the interaction of microwaves and a magnetic field, high-energy light (for example, ultraviolet light) is irradiated while reaching the substrate surface to activate the plasma. If energy is continued to be applied to the seeds, carbon atoms excited to a high energy state will exist even at a location sufficiently far from the high-density plasma generation region, making it possible to form a diamond or i-carbon film over a larger area. It was hot.

Furthermore, applying a DC bias voltage to the high-energy excited species generated by the interaction of the magnetic field and microwaves, so that a large number of excitons reached the substrate side, had the effect of increasing the rate of thin film formation.

Examples will be shown below to further explain the present invention.

〔Example〕

FIG. 1 shows a microwave plasma CVD apparatus capable of applying a magnetic field used in the present invention.

In the figure, this device comprises a plasma generation space 1 that can be maintained in a reduced pressure state, a heating space 3, an auxiliary space 2, electromagnets 5 and 5' that generate a magnetic field and their power source 25, a microwave oscillator 4, and an exhaust system. Turbo molecular pump 8, rotary pump 14, pressure adjustment valve 11, infrared heater 20 and its power source 23, infrared reflecting surface 21, substrate holder 20', substrate 10, microwave introduction window 15, gas introduction system 6, 7, It is composed of water cooling systems 18 and 18'.

First, the thin film forming substrate 10 is placed on the substrate holder 10'. This holder is made of ceramic aluminum nitride because it has high thermal conductivity and does not disturb microwaves as much as possible. This substrate holder is heated by condensing light from an infrared heater 20 using a parabolic reflecting surface 21 and a lens system 22. (e.g. 500
℃) Next, hydrogen 6 is introduced into the high-density plasma generation region 2 through the 10SCCM gas system 7, and then
Apply microwaves with a frequency of 2.45GGHz at an intensity of 500W. Furthermore, a magnetic field of approximately 2K Gauss is applied to the magnet 5,
5' to generate high-density plasma in the plasma generation space 1. At this time, the pressure in the plasma generation space 1 is maintained at 0.1 Pa. Hydrogen atoms or electrons with high energy reach the substrate 10 from this high-density plasma region and clean the surface.
Furthermore, this hydrogen supply is stopped, and carbide gases such as acetylene (C ₂ H ₂ ) and methane (CH ₄ ) are activated from the gas system 7. Carbon atoms excited with high energy are generated and the substrate 1 is heated to approximately 500℃.
These carbon atoms accumulate on the 0, forming a diamond or i-carbon film.

In FIG. 1, a Helmholtz coil system using two ring-shaped magnets 5 and 5' is used for the magnetic field. Furthermore, the electric field and
Figure 2 shows the results of examining the strength of the magnetic field.

In FIG. 2A, the horizontal axis (X-axis) is the horizontal direction of the space 20 (reactive gas release direction), and the vertical axis (R-axis) is the diametrical direction of the magnet. The curves in the drawings indicate equipotential surfaces of the magnetic field. The number shown on the line indicates the strength of the magnetic field obtained when the magnet 5 is about 2000 Gauss. By adjusting the strength of the magnet 5, a space 100 with interaction between the electrodes and the magnetic field is created.
(875±185 Gauss), it is possible to make the strength of the magnetic field approximately uniform over a large area of the formation surface of the substrate. The drawing shows an isomagnetic scene,
In particular, line 26 is an isomagnetic scene that produces ECR (electron cyclotron resonance) conditions of 875 Gauss.

Furthermore, the space 100 that produces this resonance condition is the second
As shown in Figure B, the area is set so that the electric field is maximum. The horizontal axis of FIG. 2B indicates the flow direction of the reactive gas, as in FIG. 2A, and the vertical axis indicates the strength of the electric field (electric field strength).

Then, in addition to the electric field area 100, the area 100' also corresponds to the area where the electric field becomes maximum. However, the magnetic field corresponding to this (Fig. 2A) has many isomagnetic scenes. In other words, in region 1000, there is a large variation in film thickness in the diametrical direction (vertical axis direction in FIG. 2A) of the surface on which the substrate is formed, and the resonance condition of 26' is satisfied.
A good quality film can only be formed under ECR conditions.
As a result, a uniform and homogeneous coating cannot be expected.

Of course, if you want to make it into a donut shape, that's fine.

Further, on the opposite side of the region 100 symmetrical to the origin, there is a region where the electric field is maximum and the magnetic field is constant over a wide region. When there is no need to heat the substrate, forming a film in such a space is effective. However, it is difficult to find a way to perform heating without disturbing the microwave electric field.

As a result, area 100 in Fig. 2A is the most industrial of the three areas in order to obtain a uniform film and a homogeneous coating, taking into account the ease of putting in and taking out the substrate and the ease of heating. It is estimated that it is in an excellent position for mass production.

As a result, in the present invention, when the substrate 10 is disposed in the region 100, if this substrate is circular, the radius
It has become possible to uniformly and homogeneously form a film with a radius of up to 100 mm, preferably up to 50 mm.

To make the area even larger, for example, to achieve the same uniform film thickness over an area four times as large as this, the frequency should be increased.
If it is set to 1.225 GHz instead of 2.45 GHz, the diameter of this space (direction R in Figure 2 A) can be doubled.

FIG. 3 is a drawing of equal magnetic fields and equal electric fields of the magnetic field A and the electric field B in a circular space at the position of the substrate 10 in FIG. 2. FIG. As is clear from Figure 3B,
It can be seen that the electric field can reach up to 25KV/m.

For comparison, a thin film was formed under the same conditions without applying a magnetic field. The thin film formed on the substrate at that time was a graphite film.

Furthermore, under the same conditions as in this example, the substrate temperature was
It was possible to form a diamond thin film when the temperature was 650°C or higher.

When an electron beam diffraction image of the thin film formed in this example was taken, diamond spots were observed along with a halo pattern peculiar to amorphous amorphous.
It had become a carbon film. As the substrate temperature was raised further, the halo pattern gradually disappeared and turned into a diamond at temperatures above 650°C.

Furthermore, when the substrate heating temperature was less than 150° C., it was not possible to form an i-carbon film even when a magnetic field was applied.

In this method, a polycrystalline film of silicon carbide can be formed on a substrate using a silicon carbide gas (methylsilane). Aluminum nitride coatings can also be produced by reaction of aluminide gas with ammonia. Furthermore, high melting point conductors of tungsten, titanium, molybdenum or their silicides can also be made.

〔effect〕

By employing the configuration of the present invention, it was possible to produce a film under a wider range of conditions than conventionally produced films having at least a portion of crystallinity.

Furthermore, it was possible to form a uniform thin film over a larger area than with conventional methods.

Furthermore, the produced thin film was a good film with almost no film stress in either tension or compression.

[Brief explanation of the drawing]

FIG. 1 schematically shows a microwave CVD apparatus using magnetic field/electric field interaction used in the present invention. Second
The figure shows the magnetic field and electric field characteristics by computer simulation. Figure 3 shows the characteristics of the magnetic field and electric field at a position where the electric field and magnetic field interact. 1... Plasma generation space, 10, 10'... Substrate and substrate holder, 4... Microwave oscillator,
5, 5'...External magnetic field generator, 20...Substrate heater, 100...Space with maximum electric field.

Claims (1)

[Claims] 1. A plasma generation chamber maintained in a reduced pressure state, a magnetic field generation means provided surrounding the generation chamber, and a means for supplying microwaves to the plasma generation chamber. The coating is formed using the interaction of the magnetic field and electric field. In this method, a carbide gas is introduced into the plasma generation chamber, a magnetic field and microwaves are applied to the gas from the outside, and a magnetic field region within ±21.2% of a resonant magnetic field that satisfies electron cyclotron resonance conditions is provided. A method for forming a film, comprising: providing a substrate having a surface to be formed, and forming a diamond film on the surface to be formed.