JPH0672307B2 - Plasma processing apparatus and plasma processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention applies a microwave electric field and an external magnetic field, uses their interaction, and arranges a substrate in a space where the electric field is the largest to form a film. Alternatively, the present invention relates to a thin film forming apparatus for performing etching.

[Prior Art] Conventionally, ECR (Electron Cyclotron Resonance) was used as a means for forming a thin film, and the divergent magnetic field was used to dispose the substrate "at a position" away from this resonance space. There is known a method of forming a coating having

In addition to the general Such ECR CVD (chemical vapor deposition) are known several types as a film forming means using a reactive gas, they heat CVD, heated filament CVD, chemical transport method, the 13.56MH _Z A plasma CVD method using frequency and a plasma CVD method using only microwaves are known.
In particular, in the ECR CVD method, electron energy is increased by pinching active species with a magnetic field to increase the energy, and gas is efficiently turned into plasma. However, in order to prevent the surface to be formed of the substrate from being sputtered (damaged) by the high energy of the gas by making it into plasma, the substrate is placed "at a position" away from the space satisfying this ECR condition, Film formation or anisotropic etching is performed by allowing a reactive gas that has been turned into an ion shower to reach a plasma state under high energy conditions.

The film produced by this device had an amorphous structure. In addition, the reaction pressure region had to be lowered (on the order of 10 ^-4 Torr) in order to reach the film-forming substrate by the ion shower generated by the ion source. Therefore, it is difficult to form a coating film that requires high crystallinity such as a diamond thin film. In addition, since the reaction pressure range is limited, there is a problem that a film cannot be formed under a wide range of conditions.

[Problems to be Solved by the Invention]

An object of the present invention is to provide an apparatus and a plasma processing method for performing effective plasma processing.

[Means for Solving the Problems]

The main constitution of the present invention is an apparatus for plasma-treating a substrate surface by utilizing the interaction of a magnetic field and an electric field, which is provided with a plasma reaction chamber kept under reduced pressure and surrounding the reaction chamber. First magnetic field generating means, means for supplying microwaves to the plasma reaction chamber, and second magnetic field generating means arranged perpendicular to the magnetic field of the first magnetic field generating means and along the traveling direction of the microwaves. Magnetic field generating means, and means for disposing a substrate at or near a resonance point due to the interaction between the first and second magnetic fields and the microwave.

Another main configuration of the present invention is a method of performing a plasma treatment on a substrate surface by utilizing an interaction of a magnetic field and an electric field, wherein a plasma reaction chamber kept under a reduced pressure has a first magnetic field and a micro A wave and a second magnetic field perpendicular to the first magnetic field and along the traveling direction of the microwave, and a resonance point due to interaction between the first and second magnetic fields and the microwave, or It is characterized in that the plasma treatment is performed on the substrate surface in the vicinity thereof.

The present invention is, for example, to form a film having high crystallinity. For this purpose, a substrate having a film-forming surface is arranged in the region where the electric field strength of the microwave power in the reaction chamber is maximized, and a high-density, high-energy plasma is generated near that region by an electric field / magnetic field interaction. It is a device for generating a film having a very high crystallinity.

That is, the present invention applies the force of a magnetic field to the conventionally known plasma CVD method using microwaves, and further, the interaction between the electric field and the magnetic field of microwaves, preferably ECR (electron cyclotron resonance) conditions or Whistler resonance conditions. Utilizing the interactions involved, a high density and high energy plasma is generated in a wide pressure range. Utilizing the high energy state in the resonance space, for example, a large amount of activated carbon atoms are generated, and it is possible to form coatings with excellent reproducibility and uniform film thickness, uniform characteristics, such as diamond and i-carbon film. It is what In addition, since the strength of the applied magnetic field can be changed arbitrarily, there is a feature that the ECR condition of not only electrons but also specific ions can be set.

According to one aspect of the present invention, there is provided a device for forming a thin film by utilizing an interaction between a magnetic field and an electric field, the plasma reaction chamber being kept in a reduced pressure state, and the reaction chamber provided surrounding the plasma reaction chamber. Means for generating a magnetic field by the generated coil,
Second magnetic field generating means by a permanent magnet provided perpendicular to the coil and parallel to the reaction chamber, means for supplying a microwave to the plasma reaction chamber, and a surface to be formed in a space having an electric field / magnetic field interaction. And a means for performing thin film formation by disposing a substrate having the above.

That is, the lithitano coil is adopted as a means for generating microwaves as an energy source. This Ritterano coil is characterized in that its size can be determined independently of the microwave frequency, and that the microwave generated therefrom corresponds to an approximately uniform TE ₀₁₁ mode. . Therefore, uniform and uniform plasma treatment is possible in the reaction space.

In addition to the structure of the present invention, high-density plasma is generated by the interaction between a microwave and a magnetic field, and then light having high energy reaching the surface of the substrate (for example, ultraviolet light) is irradiated to the active species. If energy is continuously applied, carbon atoms excited to a high energy state exist even at a position sufficiently distant from the high-density plasma generation region, and it is possible to form a diamond or i-carbon film in a larger area. It was

Furthermore, applying a DC bias voltage to the high energy excited species generated by the interaction between the magnetic field and the microwave so that a large amount of excited species reach the substrate side has the effect of improving the thin film formation rate. It will be apparent to those skilled in the art that the above characteristics are effective not only in the film formation but also in the etching treatment using NF ₃ or the like.

Hereinafter, the present invention will be described with reference to examples.

〔Example〕

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

In this figure, this device is a decompression reaction chamber (1), a preliminary chamber (8), a substrate holder (3) which also serves as a substrate heating device, an electromagnet (5) for generating a first magnetic field, and a second magnetic field. Permanent magnet (6), microwave power source (4), coaxial cable (7), microwave introduction part (12), exhaust system (9), and gas introduction system (10), (11) .

First, the thin film forming substrate (2) is placed on the substrate holder (3). Since this holder has high thermal conductivity and does not disturb microwaves as much as possible, ceramic aluminum nitride was used. This substrate holder can be used to
Heat to 0 ° C. Next, add hydrogen (6) to 10 SCCM gas system (11)
Through introducing the high-density plasma generation region (1), it is added in the intensity of 500W microwave frequencies outside from 2.45 GHz _Z. Further, a magnetic field of about 2K gauss is applied from the magnet (5), and a second magnetic field is applied from the permanent magnet (6) to generate high density plasma in the plasma reaction space (1).
At this time, the pressure in the plasma reaction space (1) is maintained at 0.1 Pa. Hydrogen atoms or electrons having higher energy than this high-density plasma region reach the substrate (2) and clean the surface. Furthermore, the introduction of this hydrogen gas was stopped, and a carbide gas such as acetylene (C ₂ H ₂ ) or methane was introduced from the gas system (11).
(CH ₄ ) is introduced and activated as in the case of hydrogen gas.

Then, carbon atoms excited to a high energy state were generated, and the carbon atoms were deposited on the substrate (2) heated at about 500 ° C. to form a diamond or i-carbon film.

In this case, the Helmholtz method using two ring-shaped electromagnets (5) is adopted as the means for generating the first magnetic field, and the means for generating the second magnetic field is shown in FIG. 1 and FIG. As is clear from the cross-sectional view of the vicinity of the reaction chamber in (a), an Ioffe bar parallel to the reaction chamber (1) and perpendicular to the ring-shaped electromagnet (5) is formed as shown in FIG. 2 (b). It uses a permanent magnet (6) that does.

FIG. 3 shows a state of an isomagnetic field surface formed in the reaction chamber (1) by the first and second magnetic fields. The vertical axis Z is the lateral direction of the reaction chamber (1) (that is, the direction from the microwave introduction part to the substrate), and the horizontal axis is the diameter direction of the ring-shaped coil (5).

The above-mentioned rigidano coil is characterized in that its size (diameter) can be selected regardless of the frequency of the microwave to be generated. That is, a microwave having a wavelength that is twice the axial length of the groove is generated regardless of the size of the entire coil.

Here it is chosen approximately 6cm in length of the axial grooves corresponding to the 2.45 GHz _Z.

As is apparent from FIG. 3, it can be seen that the magnetic field density in the reaction chamber is considerably increased by the first and second magnetic fields.

As a comparative example, FIG. 4 shows an isomagnetic field plane in the reaction chamber in the case of only the first magnetic field.

The distribution of the magnetic field is clearly different between the case of one magnetic field and the case of two magnetic fields, and a symmetrical distribution is obtained in the reaction chamber, and the density of the magnetic field in the reaction chamber is obviously increased by the second magnetic field. You can see that it has been raised.

The numbers in the figure indicate the magnetic flux density [Gauss].

As described above, according to the present invention, different kinds of magnetic fields are generated around the reaction chamber to generate a high density portion of the magnetic field in the reaction chamber, and the high density magnetic field and the electric field generated by the microwave interact to increase the density. It is characterized by generating high-energy plasma, which makes it possible to form a film having higher crystallinity.

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, it was possible to form a diamond thin film when the substrate temperature was 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, a diamond spot was observed along with a halo pattern peculiar to amorphous at a low temperature, and it was an i-carbon film. The halo pattern gradually disappeared as the substrate temperature was raised and the diamond was formed at 650 ° C or higher.

When the Raman spectrum of this formed film was taken, it had a slightly gradual peak near 1500 cm ^-1 , but had a sharp peak near 1333 cm ^-1 , indicating that diamond had precipitated. It could be confirmed.

Moreover, when the substrate heating temperature was set to less than 150 ° C., the i-carbon film could not be formed even if a magnetic field was applied.

In such a system, a polycrystalline silicon carbide film can be formed on the substrate by using a silicon carbide gas (methylsilane). It is also possible to form an aluminum nitride film by reacting an aluminum compound gas with ammonia. It is also possible to make high melting point conductors of tungsten, titanium, molybdenum or their silicides.

FIG. 5 shows another embodiment. The only difference from the device shown in FIG. 1 is that the position of the Ligitano coil is closer to the substrate 2 than the center plane C of the Helmholtz coil 5. With this configuration, the magnetic field in the reaction space has an effect of collecting the plasma gas toward the substrate 2.

FIG. 6 is a modification of the Ioffe bar. Here, the direction of the moment of the magnet is in the radial direction.

FIGS. 7A and 7B are views showing another form of the Ioffe bar. Here, two coils form four bars. symbol Indicates the direction of current.

It is also possible to add water, O ₂ or the like to the reactive substrate to form a film with higher crystallinity. Furthermore, although microwaves were introduced into the reaction chamber from the microwave introduction part in this example, introduction of other methods does not hinder the present invention.

〔effect〕

By adopting the configuration of the present invention, it is possible to provide a plasma processing apparatus and a plasma processing method having high plasma processing capability. For example, it becomes possible to produce a film having high crystallinity under a wider range of conditions than the condition for producing a film having crystallinity in at least a part which has been conventionally produced. Further, it becomes possible to form a uniform thin film over a large area as compared with the conventional method.

Furthermore, the produced thin film can be a good film having almost no film stress in both tension and compression.

Further, since the permanent magnet is used as the second magnetic field generating means, it is possible to reduce power consumption.

[Brief description of drawings]

FIG. 1 shows an outline of a microwave plasma apparatus using a magnetic field / electric field interaction used in the present invention. FIG. 2 (a) shows a sectional view of the device of the present invention. FIG. 2 (b) shows a coil for generating the second magnetic field. 3 and 4 show magnetic field states by computer simulation. FIG. 5 shows another microwave plasma device according to the present invention. FIG. 6 shows a modification of the Ioffe bar of FIG. FIGS. 7A and 7B show another example of the Ioffe bar. 1 ... Plasma reaction space 2 ... Substrate 3 ... Substrate holder also serving as substrate heating device 4 ... Microwave oscillator 5,5 ... External magnetic field generator

Claims (2)

[Claims] 1. An apparatus for performing a plasma treatment on a substrate surface by utilizing an interaction of a magnetic field and an electric field, wherein a plasma reaction chamber maintained under a reduced pressure and a first reaction chamber provided around the reaction chamber. Magnetic field generating means, means for supplying microwaves to the plasma reaction chamber, second magnetic field generating means arranged perpendicular to the magnetic field of the first magnetic field generating means and along the traveling direction of the microwaves And a means for disposing a substrate at or near a resonance point due to the interaction between the first and second magnetic fields and the microwave, and the plasma processing apparatus. 2. A method of performing a plasma treatment on a substrate surface by utilizing an interaction between a magnetic field and an electric field, comprising: a plasma reaction chamber kept under a reduced pressure; a first magnetic field; a microwave; A second magnetic field perpendicular to the first magnetic field and along the traveling direction of the microwave, and at the resonance point due to the interaction between the first and second magnetic fields and the microwave, or in the vicinity thereof. A plasma processing method, characterized in that the plasma processing is carried out.