JPH0317274A - Film formation - Google Patents

Abstract

PURPOSE:To form a uniform thin diamond film into a large area by applying magnetic field and microwaves to a plasma production chamber into which carbonic gas is introduced and providing a substrate in the region where the electric field intensity of microwave electric power is maximum. CONSTITUTION:A carbonic gas (e.g. acetylene, methane) is introduced through gas-introducing holes 6, 7 into a plasma production chamber 1 in an evacuated state. Subsequently, magnetic field and microwaves are applied to the above gas from magnetic field generators 5, 5' and a microwave supply means 4 in the outside of the above production chamber 1, respectively. Then, a substrate 10 is provided in the magnetic field region within + or -2.12% of the resonance magnetic field satisfying electron cyclotron resonance conditions, and a diamond film is formed on the above substrate 10.

Description

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

[Prior Art] Conventionally, Vr. Using CR (electron cyclo1-ron resonance), its emission 11k Ji kA
A method is known in which a substrate is disposed at a position J distant from this resonance space by utilizing the resonance space, and a film, particularly a film having an amorphous structure, is formed there.

More generally, such ECR CVD (chemical vapor deposition method)
In addition, several methods of film formation using reactive gases are known, including thermal CVD, heated filament CVO, chemical transport, plasma CVD using a frequency of 13.56 MI+, and plasma using only microwaves. The C'i'D method is known. Especially HCR CVt
In the I method, activated species are binned using a magnetic field to increase the energy, thereby increasing the electron energy and efficiently converting the gas into plasma. However, in order to prevent the formation surface of the substrate from being damaged due to the high energy of the gas, this EC
Film formation or anisotropic etching is performed by arranging the substrate at a "remote position" from the space that satisfies the R condition and delivering reactive gas in the form of an ion shower that avoids a plasma state under high energy conditions. I was going.

[Conventional problems]

However, in such a film formation method using a shower of reactive gas, only one of the processes of anisotropic etching, etching or deposition of an amorphous structure film, etc., is adopted depending on the type of gas. It was something.

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 aims to form a film by etching a part of the film, and preferably forms a film having crystallinity in at least a part thereof.

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,
Generates ECR (Electron Cyclotron Resonance). Furthermore, by adjusting the intensity of the R field, it becomes possible to form a film that can undergo decomposition or reaction for the first time only in this region. Examples include i-carbon (diamond or carbon coatings with microcrystalline grains) or high-melting metal or ceramic insulating coatings.

That is, the present invention adds the force of a magnetic field to the conventionally known plasma CvD method using microwaves, and further improves the interaction between the electric field of the microwave and the magnetic field, preferably ECR (electron cyclotron resonance) conditions or Whistler resonance conditions. Using these interactions, high-density, high-energy plasma is generated over a wide pressure range. Utilizing the high energy state in the resonance space, for example, a large amount of activated carbon atoms can be generated, resulting in excellent reproducibility, uniform film thickness, and
This makes it possible to form diamond, i-carbon, and other films with uniform properties. Furthermore, 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 away from the high-density plasma generation region, making it possible to form a diamond or i-carbon film over a larger area. there were.

Furthermore, applying a DC bias voltage to high-energy excited species generated by the interaction of a magnetic field and microwaves, so that a large number of excitons reach the substrate side, had the effect of improving the forming speed of the thin film. ．． 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 includes a plasma generation space (1) that can be maintained in a reduced pressure state, a heating space (3), an auxiliary space (2),
An electromagnet (5), (5°) that generates a magnetic field and its power source (25), a microwave oscillator (4), a turbo molecular bomb (8) that makes up the exhaust system, a rotary bomb (l4),
Pressure adjustment valve (l1), infrared heater (20),
and its power source (23), infrared reflective surface (2l), substrate holder (10'), substrate (IOL microwave introduction window (
15), Gas introduction system (6). (7), water cooling system (18)
, (18').

First, the thin film forming substrate (10) is placed on the base temporary holder (10'').This holder has high thermal conductivity and in order to not disturb the microwave as much as possible, aluminum nitride of Ceragoc is used. This substrate holder is heated by condensing light from an infrared heater (20) using a parabolic reflecting surface (2l) and a lens system (22) (for example, 500'C). Next, hydrogen (
6) is introduced into the high-density plasma generation region (2) through the IOSCCM gas system (7), and 2.45 GGl is introduced from the outside.
Apply microwaves with a frequency of lz at a strength of 500W.
Furthermore, a magnetic field of approximately 2K Gauss is applied to the magnet (5). (5'
), high-density plasma is applied from the plasma generation space (1
〉 At this time, the pressure in the plasma generation space (1) is maintained at Q, lPa. From this high-density plasma region, hydrogen atoms or electrons with high energy are transferred to the substrate (
1O) and clean the surface. Furthermore, this hydrogen supply is stopped and carbide gases such as acetylene (cztb) and methane (CI+4) are activated from the gas system (7).

The carbon atoms excited with high energy are then collected and deposited on the substrate (10) heated to about 500''C, forming a diamond or i-carbon film.

In Figure 1, the magnetic field consists of two ring-shaped magnets (5),
A Helmholtz coil method using (5') was adopted.

Furthermore, FIG. 2 shows the results of examining the strength of the electric and magnetic fields for the space (30) divided into four parts.

In FIG. 2 (A), the horizontal axis (X-axis) is the horizontal direction of the space (20) (reactive gas release direction), and the vertical axis (R-axis)
indicates the diameter 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 approximately 2000 Gauss. By adjusting the strength of the magnet (5), the strength of the magnetic field can be made approximately uniform over a large area of the shaped surface of the substrate in the space (100) (875 ± 185 Gauss) where the electrode-magnetic field interacts. can be done. The drawing shows an isomagnetic scene, in particular an isomagnetic scene that gives rise to the εCR (electron cyclotron resonance) condition where the line (26) is 875 Gauss.

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

Then, in addition to the electric field area (100), the area (100°) also corresponds to the maximum area. However, the 6R corresponding here
The field (Fig. 2 (A)) has an extremely large number of isomagnetic scenes. That is, in the hollow region (100'), there is a large variation in film thickness in the diameter direction of the shaped surface of the substrate (vertical axis direction in FIG. 2 (A)), and the EC that satisfies the resonance condition of (26')
A good quality film was only formed under the R condition. 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.

There is also a region on the opposite side of the region (100) symmetrical to the origin 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, considering the ease of putting in and taking out the substrate and the ease of heating, in order to obtain a uniform film and a homogeneous coating, the area (100) in Figure 2 (8) is one of the three areas. It is estimated that this is the location with the highest industrial productivity.

As a result, in the present invention, when the substrate (10) is arranged in the area (100), if this substrate is circular, the radius is 100.
1, preferably uniform in size up to a radius of 50 mm,
It became possible to form a uniform film.

For an even larger area, for example, to achieve the same uniform film thickness over an area four times larger than this, the frequency should be set to 2.45 Gll.
If z<1.225GIlz, the diameter of this space (in the R direction in FIG. 2(A)) can be doubled.

FIG. 3 is a diagram of equal magnetic fields and equal electric fields of the magnetic field (A) and electric field (B) in a circular space at the position of the substrate (10) in FIG. 2. FIG. As is clear from FIG. 3(B), it can be seen that the electric field can reach a maximum of 25XV/+.

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.

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

When an electron diffraction image of the thin film formed in this example was taken, diamond spots were observed along with a halo pattern peculiar to an amorphous film, indicating that the film was an i-carbon film. As the temperature of the substrate was further increased and the shape was improved, the halo pattern gradually disappeared and became a diamond at temperatures above 650°C.

Further, when the substrate heating temperature was less than 150° C., an i-carbon film could not be formed even if 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 taking the precautions of the present invention, it was possible to produce films under a wider range of conditions than conventionally produced films that had at least some crystallinity. Furthermore, it was possible to form a more uniform thin film than in the conventional method.

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. FIG. 2 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 film is formed by utilizing the interaction of a magnetic field and an electric field, which includes 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. 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 the magnetic field is within ±21.2% of the resonant magnetic field that satisfies the electron cyclotron resonance condition. 1. A method for forming a film, comprising: providing a substrate having a surface to be formed on, and forming a diamond film on the surface to be formed.