JPH0878333A - Plasma apparatus for formation of film - Google Patents

Abstract

PURPOSE: To obtain a plasma apparatus by which a film is formed highly uniformly and with high efficiency in a large-area region when a sputtering operation is performed by using ions in a plasma. CONSTITUTION: A plasma chamber 1 and a film-formation chamber 2 are evacuated to produce a high vacuum by means of an evacuation system 12. Ar gas is introduced from a gas introduction system 10. An ECR plasma is generated in the plasma chamber 1 by a magnetic field which is formed of microwaves introduced from a microwave power supply 15 via a square waveguide 4 and a microwave introduction window 3 and of electric power supplied to a magnetic coil 9 by a coil power supply 14. A rotation device 16 by which a sample stand 7 is arranged on the rotation symmetric axis of a target 11, by which the rotation symmetric axis of the sample stand 7 is tilted with reference to the rotation symmetric axis of the target 11 and which is tilted and turned in such a way that the point of intersection of the rotation symmetric axis of the target 11 with the rotation central axis of the sample stand 7 is situated in the opposite direction of the target 11 with reference to a sample substrate 8 is installed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming plasma apparatus for forming a thin film on a sample substrate in the production of electronic devices such as semiconductor integrated circuits and surface treatment of various materials.

[0002]

2. Description of the Related Art In recent years, as a technique for forming a thin film using plasma, ions in the plasma are accelerated to collide with a solid target composed of a film raw material, and the particles scattered by this are received by a sample substrate to form a thin film. A sputtering method for forming a is widely used. This sputtering method
Since a thin film is formed from a solid raw material, a thin film of a wide range of materials can be formed, and the compound film can be easily formed by combining various gases introduced into plasma. .

FIG. 5 is a sectional view for explaining the structure of a typical sputtering apparatus that is normally used. In FIG. 5, 2 is a film forming chamber, 7 is a sample table, 8 is a sample substrate, and 10 is a sample substrate.
Is a gas introduction system, 11 is a target, 12 is an exhaust system, 13
Is a sputtering power source.

In the thus constructed sputtering apparatus, the inside of the film forming chamber 2 is evacuated to a high vacuum by the exhaust system 12, the gas is introduced to a desired pressure by the gas introduction system 10, and the plasma is generated by the sputtering power source 13. Along with the generation of the target 11, a high voltage is applied to the target 11 to cause the ions in the plasma to collide with the target 11 to scatter target particles by sputtering, and the target particles are fixed on a sample table 7 arranged facing the target 11. The sample substrate 8 is received to form a thin film.

The sputtering power supply 13 is direct current or high frequency power, and the gas is an inert gas or a mixed gas of an inert gas and an active gas. Moreover, a wide range of thin films can be easily formed by combining the material of the target 11 and the gas. Sputtering is a phenomenon in which the target material is physically scattered by the ions that enter the target 11 with kinetic energy, and is scattered with the intensity of the COS distribution with respect to the angle from the target normal line.

The normal sputtering gas pressure is 1 to
Since the mean free path at 0.1 Pa is about several cm to several tens of cm, these scattered sputtered particles reach the sample substrate 8 almost linearly. Therefore, the film formation uniformity within the sample substrate 8 (including between sample substrates when a plurality of substrates are simultaneously formed into a thin film) depends on the angle and distance of the target expected from the position of the sample substrate of interest. It will be.

A sputtering apparatus of this kind is disclosed, for example, in the Electron / Ion Beam Handbook, edited by Japan Society for the Promotion of Science, 132nd Committee, PP503-508, Nikkan Kogyo Shimbun (1986).

FIG. 6 is a sectional view for explaining the basic structure of a conventional sputter type electron cyclotron resonance plasma deposition apparatus, in which the same parts as those in FIG. 5 described above are designated by the same reference numerals. In FIG. 6, 1 is a plasma chamber, 9 is a magnetic coil, and 15 is a microwave power source.

In the sputtering type ECR plasma deposition apparatus thus constructed, the plasma chamber 1 and the film forming chamber 2 are evacuated to a high vacuum by the exhaust system 12, and the gas is introduced to a desired pressure by the gas introduction system 10. Microwave power is supplied from the microwave power source 15 and a magnetic field is applied by the magnetic coil 9 to generate plasma in the plasma chamber 1 by electron cyclotron resonance (ECR) and surround the plasma transported from the plasma chamber 1. Electric power is supplied from the sputtering power source 13 to the arranged target 11, the target particles are scattered by sputtering, and the target particles are received by the sample substrate 8 fixed to the sample table 7 to form a thin film.

[0010]

However, in the conventional sputtering apparatus described with reference to FIG. 5 described above, when it is attempted to obtain high film formation uniformity, the angle and distance of the target 11 desired from that region become substantially equal. Therefore, it is necessary to determine the diameter of the target 11 and the distance between the target 11 and the sample substrate 7.

As an example, a target that is sufficiently larger than the region (size) for which high film formation uniformity is desired can be realized by reducing the distance between the target and the sample substrate. In this case, the film can be formed at a relatively high speed, but most of the sputtered particles are scattered to a region other than the sample substrate, resulting in a significant decrease in efficiency. Further, since the sputtered particles fly into the sample substrate from a wide angle, there is a problem that the coverage of the sample substrate having a large surface step such as VLSI is deteriorated.

Further, in another example, even if the distance between the sample substrate and the target is made sufficiently large, symmetrical to the above-mentioned example, high film formation uniformity can be realized. In this case, the target size can be made small, and sputtered particles fly to the sample substrate at a narrow angle, which has the advantage of improving the coverage.
However, since the distance between the sample substrate and the target becomes large, the utilization efficiency of sputtered particles is extremely reduced, and it becomes difficult to obtain a practical film formation rate.

In yet another example, it is possible to change the uniformity of plasma generation and change the density of particles scattered from the target to effectively obtain high uniformity on the sample substrate. Problems such as difficulty in operation and complicated target configuration occur.

Further, in the conventional sputter type electron cyclotron resonance plasma deposition apparatus described in FIG. 6 described above, a high quality thin film can be formed at low temperature at high speed due to the ease of supplying the raw material by sputtering and the effect of supporting the surface reaction by ECR plasma. It has the features that can be done. However, the uniformity of film formation has the same problem as in the above-described conventional sputtering apparatus from the aspect of the principle that the film forming raw material is physically supplied by the sputtering of the target.

That is, it is effective to reduce the distance between the sample substrate and the target for high-speed film formation, but the film formation uniformity decreases. On the other hand, high film formation uniformity can be achieved by increasing the distance between the sample substrate and the target, but there has been a problem that the film formation rate sharply decreases.

Therefore, the present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to achieve high efficiency and high uniformity in a large area when sputtering using ions in plasma. An object of the present invention is to provide a film forming plasma device capable of forming a film.

[0017]

In order to achieve such an object, the present invention provides a plasma generating means for introducing a plasma generating gas to generate a plasma flow of plasma, and a plasma so as to come into contact with the plasma flow. Target made of a film-forming material arranged concentrically with the flow, means for scattering the particles of the film-forming material from the target into the plasma flow by using the ions of the plasma flow, and scattering of the particles of the film-forming material In a film forming plasma apparatus having a substrate mounting table for mounting and fixing a film forming sample substrate irradiated by a plasma flow, the substrate mounting table is arranged on the rotational symmetry axis of the target, The rotation center axis is tilted with respect to the rotation symmetry axis of the target, and the intersection of the rotation symmetry axis of the target and the rotation center axis of the substrate mounting table becomes the sample formation substrate. It is provided with a rotating means for rotating inclined so as to be positioned in the opposite direction of the targets by.

[0018]

According to the present invention, in the thin-film forming plasma apparatus for forming a film by utilizing the sputtering of the target, the film is formed uniformly in a large area on a time-averaged basis by paying attention to the movement of the sputtered particles.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings. (Embodiment 1) FIG. 1 is a sectional view of a sputtering type ECR plasma deposition apparatus for explaining the configuration of an embodiment of a film forming plasma apparatus according to the present invention. In FIG. 1, 1 is a plasma chamber, 2 is a film forming chamber, 3 is a microwave introduction window, 4 is a rectangular waveguide, 5 is a plasma extraction window, 6 is a plasma flow,
7 is a sample stage, 8 is a sample substrate, 9 is a magnetic coil, 10 is a gas introduction system, 11 is a target, 12 is an exhaust system, 13 is a sputtering power supply, 14 is a coil power supply, 15 is a microwave power supply, and 16 is a sample substrate. It is a rotating device for inclining and rotating the sample table 7 on which 8 is mounted and fixed.

In such a structure, the plasma chamber 1 and the film forming chamber 2 are evacuated to a high vacuum (usually 10
^-2 Pa), and the gas introduction system 10 introduces the sputter gas or the reactive gas alone or in a mixture to obtain a desired pressure, and the microwave power source 15 supplies the rectangular waveguide 4 and the microwave introduction window 3 Electron cyclotron resonance (ECR) plasma is generated in the plasma chamber 1 by the microwave introduced through the coil and the magnetic field formed by the electric power supplied to the magnetic coil 9 by the coil power supply 14.

A magnetic coil 9 is installed inside the plasma chamber 1
Magnetic field intensity that satisfies CR conditions (eg, magnetic flux density of 875 Gauss for microwave frequency of 2.45 GHz)
And a divergent magnetic field in which the magnetic field strength weakens with a proper gradient from the plasma chamber 1 to the sample stage 7. The interaction between this divergent magnetic field and the magnetic moment of the electrons that are accelerated by the ECR and move at high speed makes the plasma chamber 1
A static electric field for accelerating and transporting ions toward the sample stage 7 is formed in a self-aligned manner, and a plasma flow 6 is formed.

In the case of sputtering type ECR plasma deposition, a cylindrical target 11 is arranged immediately below the plasma extraction window 5 so as to surround the plasma flow 6, and a negative potential is applied to this from a sputtering power source 13 to generate plasma with a large current density. A part of the ions transported in the stream 6 is accelerated and collided with the target 11 to supply the film forming raw material by sputtering. The sample substrate 8 placed on the sample stage 7 placed downstream of the plasma flow 6 receives the sputtered particles to form a film, and the low energy and high current density ion irradiation in the plasma flow 6 causes high quality and high speed. A film can be formed.

The film forming raw material is supplied from the fixed target 11 by sputtering, and the compound film can be formed by introducing gas such as oxygen and nitrogen. The rotation device 16 mounted with the sample table 7 on which the sample substrate 8 is arranged has a configuration in which the sample table 7 and the sample substrate 8 are rotated while being inclined with respect to the rotational symmetry axis of the target 11. On the film surface, the rotation center is located at a position distant from the intersection of the rotational symmetry axis of the target 11 and the film formation surface of the sample substrate 8 in the tilt direction. Since the rotating device 16 can be configured by using various known configurations, detailed description thereof will be omitted.

Next, this configuration will be described in detail with reference to FIG. In the figure, the same reference numerals as those in FIG. 1 denote the same members as those in FIG. In FIG. 2, A is the rotational symmetry axis of the rotationally symmetric target 11, B is the rotation center axis around which the sample substrate 8 rotates, and C is the thin film formation plane of the sample substrate 8 and passes through the rotation center axis B of the sample substrate 8. Coordinate axes, P is the tilt center of the sample substrate 8 and is the intersection of the target rotation symmetry axis A and the sample substrate rotation center axis B, Q is the rotation center of the sample substrate 8, and the sample rotation center axis and the thin film of the sample substrate 8 An intersection with the formation surface, R is an intersection between the target rotational symmetry axis A and the thin film formation surface of the sample substrate 8, and θ is an inclination angle of the sample substrate 8, and the target rotational symmetry axis A
And the sample rotation center axis B, 17 is a sputtered particle. In the figure, the axis of rotational symmetry A, the axis of rotation B, and the coordinate axis C are on the same plane.

In such a structure, the target 11
The sputtered particles 17 scattered from the surface 1
Almost no scattering at a vacuum degree of 0 ^-2 Pa,
It flies in the direction of the sample substrate 8. Therefore, the density of the sputtered particles 17 on the sample substrate 8 is inversely proportional to the square of the distance from the sputtering point of the target 11. The thickness of the film formed at a point on the sample substrate 8 corresponds to the integral of the density of sputtered particles from the target 11 that can be expected from that point. Therefore, the sample substrate 8 is not tilted (θ = 0 degree)
In this case, the film thickness is large in the central portion of the sample substrate 8 and small in the peripheral portion, so that high uniformity cannot be obtained.

In this embodiment, axes A, B and C centering on the point P are used.
By tilting the sample table 7 in a plane including the point S, the maximum supply position of the sputtered particles 17 is set to a point R distant from the sample rotation center Q, and the distance between the sample substrate 8 and the target 11 is changed. By rotating the sample substrate 8 by the rotating device 16, the uniformity can be improved on a time average basis. The method of changing the position and orientation of the sample substrate 8 is not limited to the above-described method, for example, tilting is performed in a state where the points Q and R are coincident with each other, and then the center of rotation is set to the position of the point Q. The same is true even if it is moved vertically to A.

FIG. 3 is a diagram showing film forming characteristics by the above-mentioned sputtering type ECR plasma deposition apparatus. In the film forming conditions shown in FIG. 3, the target is 99.99% Al, and the target has a cylindrical shape with an inner diameter of 150 mm and a height of 30 mm. The distance from the cylindrical target to the sample substrate is 150 mm on the target rotational symmetry axis A. The plasma system and the film forming chamber were evacuated to a high vacuum of 7 × 10 ⁻⁶ Pa by an exhaust system, and Ar was introduced into the film forming chamber at 25 cc / min.
^-2 Pa vacuum level, current is supplied to the coil by the coil power supply to form an ECR magnetic field in the plasma chamber, 800 W
The microwave was supplied by a microwave power source to generate plasma.

A negative DC voltage of 600 V was applied to the target to accelerate and collide some ions in the plasma flow with the target, and the film forming raw material was supplied by sputtering. In the film formation, the tilt angle (θ) of the sample substrate and the shift amount (QR) from the target rotational symmetry axis A were changed. The rotation speed of the sample substrate was about 15 RPM, and the film formation time was about 20 minutes. FIG. 3 shows the distribution of the uniform region of ± 5% at this time.

In the structure shown in FIG. 2, when the point Q and the point R are tilted so that they coincide with each other (shift = 0), the uniformity improves with the tilt, and ± 30% at a tilt angle of 30 °. The uniform region has a diameter of about 90 mm, which is improved by about 30% as compared with the inclination angle of 0 degree. Greater uniformity can be expected by increasing the tilt angle,
Since the coating property for fine irregularities on the sample surface deteriorates,
It was difficult to apply to high-performance electronic devices.

When the sample rotation center axis is shifted without inclining the sample substrate, the shift amount is 1 when the shift amount is 50 mm.
The uniformity is improved by about 5%. Also in this case, if the shift amount is increased, a greater improvement in uniformity can be expected, but not only sputtered particles flying in the direction of the sample substrate cannot be effectively used for film formation, but also a part or all of the sample substrate can be used. Exists in a region where the plasma flow transported from the plasma chamber is not irradiated, which makes it difficult to form a high-quality film by plasma irradiation.

On the other hand, when the tilt angle and the shift amount are used together, the respective effects are synergistically exerted. For example, when the substrate tilt angle is 25 degrees and the shift amount is 40 mm, the ± 5% uniform area is φ150 mm. As compared with the case where the substrate tilt angle is 0 degree, the uniformity improvement of 2.1 times or more can be achieved. In addition, the film forming rate at this time is about 80% as compared with the case where both the substrate tilt angle and the shift amount are 0, and the film forming rate at the apex portion of the convex type film forming distribution is averaged by improving the uniformity. It is comparable to the one that has been made into. By using the substrate tilt angle and the shift amount together in this way, it is possible to form a high-quality film excellent in step coverage while maintaining a high film formation rate while irradiating a plasma flow within the range where the target is expected.

(Embodiment 2) FIG. 4 is a sectional view of a flat plate RF magnetron sputtering apparatus for explaining the structure of another embodiment of the film forming plasma apparatus according to the present invention. In the figure,
The same parts as those in FIGS. 1 and 2 are designated by the same reference numerals.
In FIG. 4, 18 is a magnet. This magnet 18 has a magnetic flux (B) parallel to the sputtering electric field (E) generated perpendicularly to the target 11 in the sputtering region of the target 11.
Is generated and high-density plasma is generated in this E × B region to perform high-speed film formation.

In this embodiment, the cylindrical target shown in FIG. 2 has the same structure as the case where the discharge surface is developed in the direction of the sample substrate, and the same effect as in FIG. 3 was confirmed. If the operating vacuum degree in the sputter type ECR plasma deposition apparatus of FIG. 1 is 10 ^-2 to 10 ^-1 Pa and the operating vacuum degree in the magnetron sputtering apparatus is 10 ^-1 Pa, most of the sputtered particles are This is because it reaches the sample substrate without colliding with gas molecules existing in the middle.

Conventionally, in order to obtain a desired film formation uniformity,
We have moved the magnets or changed the discharge (sputtering) conditions, but since these also affect the film formation quality, it is not possible to satisfy both high uniformity and high quality. It was extremely difficult. On the other hand, according to the present embodiment, since the uniformity can be controlled independently of the sputtering (discharge) conditions that affect the quality of the formed film, the film can be formed with good reproducibility and controllability.

Further, according to this structure, in the film forming method of supplying the film forming raw material by sputtering, most of the sputtered particles reach the sample substrate 8 without colliding with gas molecules existing in the middle. Because you can
A highly uniform film can be formed.

In the above-mentioned embodiment, the case where the flat plate RF magnetron sputtering device is used as the film forming plasma device has been described, but it is apparent that the same effect can be obtained by using the DC magnetron sputtering device instead. is there.

Further, the present invention can be similarly applied to an ion beam sputtering film forming apparatus in which high-energy ions are extracted from the plasma in a shower shape and collide with a target to form a film on a sample substrate.

When the gas pressure is such that most of the sputtered particles can be directly incident on the sample and the distance between the target and the sample, the normal DC sputtering as shown in FIG. 5 is performed. The same effect can be obtained in the apparatus or the RF sputtering apparatus.

Further, in the above-mentioned embodiment, a cylinder or a disk was used as the shape of the target for the convenience of the experiment, but it goes without saying that it may be oval or polygonal.

[0040]

As described above, according to the present invention,
Uniformity of film formation can be improved independently of supply of film forming raw material by sputtering, and high quality film formation is possible in film formation on electronic devices that require fine and highly accurate film formation. The extremely excellent effect of becoming

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a sputtering type ECR plasma deposition apparatus for explaining the configuration of an embodiment of a film forming plasma apparatus according to the present invention.

FIG. 2 is a perspective view showing a detailed configuration of the sputtering type ECR plasma deposition apparatus shown in FIG.

3 is a diagram showing film formation characteristics by the sputtering type ECR plasma deposition apparatus shown in FIG.

FIG. 4 is a cross-sectional view of a flat plate RF magnetron sputtering apparatus for explaining the configuration of another embodiment of the film forming plasma apparatus according to the present invention.

FIG. 5 is a cross-sectional view showing the configuration of a conventional sputtering device.

FIG. 6 is a sectional view showing a configuration of a conventional sputtering type ECR plasma deposition apparatus.

[Explanation of symbols]

1 ... Plasma chamber, 2 ... Film forming chamber, 3 ... Microwave introduction window,
4 ... Rectangular waveguide, 5 ... Plasma extraction window, 6 ... Plasma flow, 7 ... Sample stage, 8 ... Sample substrate, 9 ... Magnetic coil, 1
0 ... Gas introduction system, 11 ... Target, 12 ... Exhaust system, 1
3 ... Sputter power supply, 14 ... Coil power supply, 15 ... Microwave power supply, 16 ... Rotating device, 17 ... Sputter particle, 18 ...
magnet.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seitaro Matsuo 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (3)

[Claims] 1. A plasma generating means for introducing a plasma generating gas to generate a plasma flow of plasma, and a target made of a film forming material concentrically arranged with the plasma flow so as to come into contact with the plasma flow. A means for scattering particles of the film-forming material from the target into the plasma flow by using ions of the plasma flow; and a film formation irradiated by the plasma flow in which the particles of the film-forming material are scattered. In a film forming plasma apparatus having a substrate mounting table for mounting and fixing a sample substrate for use, the substrate mounting table is disposed on a rotational symmetry axis of the target, and a rotation center axis of the substrate mounting table is the target. The sample forming substrate is inclined with respect to the rotational symmetry axis, and the intersection of the rotational symmetry axis of the target and the rotation center axis of the substrate mounting table is the sample formation substrate. Film forming plasma apparatus characterized in that a rotating means for tilting to rotate so as to be located in the opposite direction of the target for. 2. The film forming plasma apparatus according to claim 1, wherein the plasma generating means is a plasma generating apparatus for generating plasma by electron cyclotron resonance discharge. 3. The film forming plasma apparatus according to claim 1, wherein the plasma generating means is a plasma generating apparatus that generates plasma by direct current or high frequency discharge.