JP2715277B2 - Thin film forming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention applies a microwave electric field, an external magnetic field, and the interaction between them.
Also, the present invention relates to a thin film forming apparatus for arranging a substrate in a space where the electric field is the largest and for forming or etching a film.

[0002]

2. Description of the Related Art Conventionally, ECR (Electron Cyclotron Resonance) has been used as a means for forming a thin film, and a substrate has been disposed at a position "distant from the resonance space" by utilizing the divergent magnetic field. There is known a method of forming a coating having the following.

[0003] More generally, such ECR CVD
In addition to the (chemical vapor deposition) it is known several types as a film forming means using a reactive gas, they heat CVD, heated filament CVD, chemical transport method, 13.56MH _z
And the plasma CVD method using only microwaves are known. Especially ECRC
In the VD method, the active species are pinched by a magnetic field, and the energy is increased to increase the electron energy, thereby efficiently converting the gas into plasma. However, the formation of plasma prevents the formation surface of the substrate from being sputtered (damaged) by the high energy of the gas.
The substrate is placed at a position "distant from" the space that satisfies the CR conditions, and the film formation or anisotropic etching is performed by reaching the ion showered reactive gas that avoids the plasma state under high energy conditions. I was going.

[0004] The film formed by this apparatus had an amorphous structure. Also, in order to allow the ion shower generated by the ion source to reach the film forming substrate,
It was necessary to lower the reaction pressure range (on the order of 10 ^-4 Torr). Therefore, it has been difficult to form a film that requires high crystallinity, such as a diamond thin film. Further, since the reaction pressure range is limited, there is a problem that a film cannot be formed under a wide range of conditions.

According to the present invention, for example, a film having high crystallinity is formed. For this purpose, a substrate with a film-forming surface is placed in the region of the reaction chamber where the electric field intensity of microwave power is highest, and near that region, high-density, high-energy plasma is generated by the interaction of electric and magnetic fields. It is a device that generates a very high crystalline film.

That is, the present invention applies a magnetic field force to a conventionally known plasma CVD method using a microwave, and furthermore, an interaction between a microwave electric field and a magnetic field, preferably E.
Utilizing interactions including CR (electron cyclotron resonance) conditions or Whistler resonance conditions, a high-density, 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 diamond, i-carbon films, etc. with excellent reproducibility, uniform film thickness, and uniform characteristics. It is what it was. In addition, since the strength of the applied magnetic field can be arbitrarily changed, there is a feature that not only electrons but also ECR conditions of specific ions can be set.

[0007] The thin film forming apparatus of the present invention has a magnetic structure.
A thin film on the substrate surface using the interaction of electric and electric fields
An apparatus for forming a thin film, wherein the apparatus is maintained at a reduced pressure.
A plasma reaction chamber, provided surrounding the plasma reaction chamber;
A first magnetic field generating means using a coil,
A space between the first magnetic field generating means and the plasma reaction chamber;
Perpendicular to and in front of the first magnetic field generating means by the coil
A second magnetic field generating means provided in parallel with the reaction chamber;
Means for supplying microwaves to the plasma reaction chamber;
In front of space with electric and magnetic field interaction in plasma reaction chamber
Means for disposing the substrate.
You.

That is, a first magnetic field generated from a Helmholtz-type coil and an I-axis provided in a direction perpendicular to the coil.
The plasma generated by the microwave in the reaction space is confined by the second magnetic field generated by the permanent magnet constituting the off bar, and the first and second magnetic fields realize a high-density magnetic field, thereby realizing high density and high energy. This is a device that generates a plasma and forms a film with extremely high crystallinity.

[0009] In addition to the structure of the present invention, after generating high-density plasma by interaction of a microwave and a magnetic field, light having a high energy (for example, ultraviolet light) is irradiated to the surface of the substrate. However, when energy is continuously applied to the active species, carbon atoms excited to a high energy state exist even at a position sufficiently distant from the high-density plasma generation region, and a diamond or i-carbon film is formed in a larger area. Was also possible.

Further, 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 the excited species reach the substrate side has an effect of improving the thin film formation speed. there were. It will be apparent to those skilled in the art that the above features are effective not only for film formation but also for etching using NF ₃ or the like. Examples are shown below to further describe the present invention.

[0011]

FIG. 1 shows a microwave plasma CVD apparatus capable of applying a magnetic field used in the present invention. In this figure, this apparatus includes a decompression reaction chamber (1), a preparatory chamber (8), a substrate holder (3) also serving as a substrate heating device, an electromagnet (5) for generating a first magnetic field, and generating a second magnetic field. A permanent magnet (6), a microwave oscillator (4), a microwave waveguide (7), a microwave introduction window (12), an exhaust system (9), and a gas introduction system (10) and (11). ing.

First, a thin film forming substrate (2) is set on a substrate holder (3). This holder has high thermal conductivity,
In addition, ceramic aluminum nitride was used to disturb microwaves as little as possible. The substrate is heated to, for example, 500 ° C. by the substrate holder. Next, hydrogen (6)
It is introduced into the high-density plasma generation region (1) through the 0SCCM gas system (11), and a microwave having a frequency of 2.45 GHz is applied from the outside at a power of 500 W. 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 kept at 0.1 Pa.
Hydrogen atoms or electrons having higher energy than the high-density plasma region reach the substrate (2) and clean the surface.
Further, the introduction of the hydrogen gas is stopped, and a carbide gas, for example, acetylene (C ₂ H ₂ ) or methane (CH ₄ ) is introduced from the gas system (11) and activated in the same manner as in the case of the hydrogen gas.

[0013] Then, carbon atoms excited to a high energy state are generated, and on the substrate (2) heated at about 500 ° C,
The carbon atoms increased in volume, and a diamond or i-carbon film was formed. In this case, as a means for generating the first magnetic field, a Helmholtz method using two ring-shaped electromagnets (5) is adopted, and as means for generating the second magnetic field, FIGS. 2), the reaction chamber (1) as shown in FIG.
Parallel to and perpendicular to the ring-shaped electromagnet (5).
The permanent magnet (6) constituting fe bar is adopted.

FIG. 3 shows the state of the isomagnetic field formed in the reaction chamber (1) by the first and second magnetic fields. This is the reaction chamber (1) drawn according to the coordinate system shown in FIG.
Within the isomagnetic field. The vertical axis Z is the horizontal direction of the reaction chamber (1) (that is, the direction from the microwave introduction window to the substrate), and the horizontal axis is the diameter direction of the ring-shaped coil (5). The magnetic field density at the first and second
It can be seen that it is considerably increased by the magnetic field.

As a comparative example, FIG. 4 shows a uniform magnetic field surface in the reaction chamber when only the first magnetic field is used. One magnetic field and 2
In the two cases, the distribution of the magnetic field is clearly different, a symmetric distribution is obtained in the reaction chamber, and the density of the magnetic field in the reaction chamber is clearly increased by the second magnetic field. . The figures in the figure indicate the magnetic flux density [Ga
uss].

As described above, according to the present invention, different types 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 interaction between the high-density magnetic field and the electric field generated by the microwaves. Thus, a plasma of higher density and higher energy is generated, thereby making 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. Further, when the substrate temperature was set to 650 ° C. or higher under the same conditions as in this example, it was possible to form a diamond thin film. When an electron diffraction image of the thin film formed in this example was taken,
Diamond spots were observed together with the halo pattern peculiar to amorphous, and the film was an i-carbon film.
As the substrate temperature was further increased, the halo pattern gradually disappeared and diamond was formed at 650 ° C. or higher.

When the Raman spectrum of the formed film was measured, it had a slightly gentle peak near 1500 cm ^-1 , but a sharp peak near 1333 cm ^-1 , indicating that diamond was deposited. Was confirmed. When the substrate heating temperature is less than 150 ° C.,
Even when a magnetic field was applied, an i-carbon film could not be formed. In such a method, a silicon carbide polycrystalline film can be formed on the substrate by using a silicon carbide gas (methyl silane). An aluminum nitride film can be formed by a reaction between an aluminum compound gas and ammonia.
In addition, high melting point conductors of tungsten, titanium, molybdenum or silicides thereof can be made.

FIG. 5 shows another embodiment. The only difference from the apparatus shown in FIG. 1 is that the position where microwaves are introduced into the reaction vessel 1 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 plasma gas toward the substrate 2. FIG. 6 is a modified example of the Ioffe bar. Here, the direction of the moment of the magnet is the radial direction. FIGS. 7A and 7B show Ioffe b
It is a figure showing other forms of ar. Here, two coils form four bars. The symbols indicate the direction of the current.

It is also possible to add water, oxygen and the like to the reactive substrate to form a film having higher crystallinity. Furthermore, according to the present embodiment, microwaves are introduced into the reaction chamber through the microwave introduction window, but introduction by other methods does not hinder the present invention.

[0021]

By adopting the constitution of the present invention, it is possible to produce a film having high crystallinity under a wider range of conditions than the conventional conditions for producing a film having at least a portion of crystallinity. Further, it was possible to form a uniform thin film over a large area as compared with the conventional method. Further, the produced thin film was a good film having almost no film stress in both tension and compression. Further, since a permanent magnet is used as the second magnetic field generating means, power consumption can be reduced.

[Brief description of the drawings]

FIG. 1 schematically shows a microwave plasma apparatus using a magnetic field / electric field interaction used in the present invention.

FIG. 2 (A) shows a cross-sectional view of the device of the present invention.

FIG. 2 (B) shows a coil for generating a second magnetic field.

FIG. 3 shows a magnetic field state by computer simulation.

FIG. 4 shows a magnetic field state by computer simulation.

FIG. 5 shows another microwave plasma device according to the present invention.

FIG. 6 shows a modification of Ioffe bar in FIG.

FIG. 7A shows another example of Ioffe bar.

FIG. 7B shows another example of Ioffe bar.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plasma reaction space 2 Substrate 3 Substrate holder also serving as substrate heating device 4 Microwave oscillator 5 External magnetic field generator 6 External magnetic field generator

Continuation of front page (56) References JP-A-59-136130 (JP, A) JP-A-61-213377 (JP, A) JP-A-63-217620 (JP, A)

Claims (1)

(57) [Claims] 1. The method of claim 1 wherein the interaction between a magnetic field and an electric field
A thin film forming apparatus for forming a thin film on a surface of a plate, comprising: a first plasma reaction chamber maintained in a reduced pressure state; and a coil provided around the plasma reaction chamber.
Magnetic field generating means, first magnetic field generating means using the coil , and the plasma reaction
First magnetic field generating means using the coil between the first magnetic field and the room
Magnetic field provided perpendicular to and parallel to the reaction chamber
Generating means, means for supplying microwaves to the plasma reaction chamber, and space having an electric / magnetic field interaction in the plasma reaction chamber
Means for disposing the substrate in
Thin film forming equipment.