JPH08236448A - Device and method for sputtering - Google Patents

Abstract

PURPOSE: To uniformly treat a substrate with high-density plasma having a high degree of vacuum even when the area of the substrate is large. CONSTITUTION: A ring-like microwave supplying port is provided around the side face of the dielectric plate 18 of a target set as part of a vacuum vessel 11 having an evacuating means and reactive gas introducing port 15 so that the port can be communicated with the vessel 11 and a metallic electrode 20 is installed to the back of the plate 18. Therefore, the target is evenly sputtered, because microwave power is uniformly radiated in the vessel 11 and high-density plasma is generated from a reactive gas due to the interaction between a magnetic field and reactive gas, and then, the ions in the uniform plasma are made incident to the dielectric plate 18 of the target in an accelerated state by the high-frequency power impressed upon the electrode on the back of the plate 18 and the sputtering takes place.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma surface treatment technique, and more particularly to a sputtering apparatus and a sputtering method for forming a dielectric film used in a thin film forming process for semiconductors, liquid crystal panels, solar cells and the like.

[0002]

2. Description of the Related Art In recent years, in a sputtering apparatus, efforts have been actively made to realize high quality, high speed, large area, and low damage in order to improve the function of the device and reduce its processing cost. There is. The conventional microwave sputtering apparatus will be described below. As an example of a conventional microwave sputtering device, a sputter type ECR is used.
(Electron Cyclotron Resonance) A microwave plasma deposition apparatus is disclosed in "Applied Physics" (Matsuoka, Ono: Vol. 57, P1301, 1988). This microwave sputtering device is characterized by stable discharge even in high vacuum. The microwave sputtering device will be described below.

FIG. 5 is a sectional view of a reaction chamber of a conventional microwave sputtering apparatus. In FIG. 5, reference numeral 1 denotes a resonance chamber, which basically has a cylindrical resonance mode TE112 shape in a microwave vacuum. Waveguide 2 in the resonance chamber 1
2.45 GHz microwave is introduced through the vacuum shield window 3 from. 875 so that the ECR condition is satisfied for the microwave of 2.45 GHz in the resonance chamber 1.
Gaussian magnetic field strength is applied by the external coil 4.
Argon or the like as a discharge gas is introduced into the resonance chamber 1 through the gas inlet 5. A cylindrical target 8 is installed so as to be in contact with the plasma outlet 6 and surround the plasma flow 7. A substrate holder 9 and a substrate 10 are installed below the substrate holder 9.

The operation of the microwave sputtering apparatus constructed as above will be described below. First, using argon as a discharge gas, 10 ⁻⁴ to 10 ⁻³ T
Plasma is generated in the resonance chamber 1 in the pressure range of orr. The plasma flows out from the plasma extraction hole 6 as a plasma flow 7 of low energy ions (several eV to several tens eV) due to the divergent magnetic field gradient of the coil 4. At this time, when a negative voltage (DC or high frequency: 13.56 MHz) is applied to the target 8, the ions in the plasma flow 7 are incident on the target 8 and sputtering occurs. Some of the particles sputtered from the target 8 fly toward the substrate 10 to form a thin film. Further, as another example of the microwave sputtering apparatus, it is shown in JP-A-4-36465 as a microwave plasma generating apparatus.

[0005]

However, in the above-mentioned first conventional structure, the size of the apparatus is increased because the plasma generating section and the sputtering section are separated. In addition, since the target is ring-shaped, it is difficult to process the target and is expensive. Further, in the second conventional configuration, since the microwave is radiated from the open end of the coaxial waveguide, the microwave electric field strength in the central portion of the target becomes stronger and more uneven than that in the surroundings, and the central portion of the target is consumed. However, there is a problem in that the sputtering efficiency becomes faster, the utilization efficiency is lowered, and the uniformity of the sputtering deposited film is poor.

The present invention solves the above-mentioned conventional problems, and provides a sputtering apparatus which can be used at a high degree of vacuum and a disk target can be used efficiently, and which is small and has good uniformity. To aim.

[0007]

In order to achieve this object, a sputtering apparatus having a first structure according to the present invention has a dielectric plate installed as a part of a vacuum container and an outer peripheral side surface of the dielectric plate. A coaxial waveguide installed so as to communicate with a space formed by the central conductor and the outer conductor of the coaxial waveguide, microwave power supply means connected to the coaxial waveguide, and the outside of the dielectric plate vacuum container. It is provided with a metal electrode placed on a plane, a means for applying high frequency power to the metal electrode, and a means for generating a magnetic field on the surface portion of the dielectric plate in the vacuum container.

According to the second aspect of the sputtering apparatus of the present invention, the semi-coaxial cavity resonator having the central conductor and the outer conductor each having an opening at the center and having microwave power supply means. A dielectric plate installed so as to form a part of a vacuum container in an opening of a central conductor of the semi-coaxial cavity resonator and a central part of an outer conductor; and a metal installed on a plane outside the vacuum container of the dielectric plate. It is preferable to include an electrode, a unit for applying high-frequency power to the metal electrode, and a unit for generating a magnetic field on the surface of the dielectric plate inside the vacuum container.

The plasma processing method according to the present invention is
The dielectric material is installed as a part of the vacuum container, and the microwave power is supplied by a coaxial waveguide in a reverse radial direction from the outer peripheral side of the dielectric plate having a metal electrode on the outer surface of the vacuum container toward the center. Using plasma generated by the interaction between the surface wave of the microwave radiated from the plate surface and the magnetic field formed in the radiation region of the surface wave, and the bias potential of the high frequency power supplied to the metal electrode of the dielectric plate. Then, the dielectric plate is sputtered, and the dielectric thin film is deposited on the substrate to be processed.

[0010]

According to the first configuration of the present invention, the microwave power supplied from the ring-shaped microwave radiating portion of the coaxial waveguide to the outer peripheral side surface of the dielectric plate in the reverse radial direction toward the center is:
Surface waves are evenly generated in the circumferential and radial directions on the substrate side of the dielectric plate, and the microwave power is uniformly radiated into the vacuum vessel, which interacts with the magnetic field to make the reaction gas uniform. Turn into high density plasma. Ions in the uniform plasma are accelerated and incident on the target dielectric plate by the high frequency power applied to the electrode on the back surface of the dielectric plate, and sputtering occurs. Therefore, since the target is uniformly sputtered, the uniformity of film formation is good, and the utilization efficiency of the target can be improved. Moreover, high-density plasma generation and sputtering can be performed with a high degree of vacuum, and the device size can be reduced.

Further, according to the second configuration of the present invention, according to the preferable configuration of using the semi-coaxial cavity resonator, the coaxial waveguide has a large diameter even when processing a large-area substrate. There is no need to expand, and the device can be downsized.

Further, according to the structure of the present invention, since the sputtering is performed with high-vacuum and high-density plasma, the substrate can be uniformly processed at high speed, and the utilization efficiency of the target can be improved.

[0013]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a reaction chamber in a first embodiment of a sputtering apparatus according to the present invention.

In FIG. 1, 11 is a metallic vacuum container,
12 is a vacuum exhaust system, 13 is a substrate holder, 14 is a substrate to be processed, 15 is a gas inlet for introducing a reaction gas, 16
Is a center conductor of the coaxial waveguide, and 17 is an outer conductor of the coaxial waveguide. The center conductor 16 and the outer conductor 17 form a coaxial waveguide and transport microwaves. 18 is the target SiO ₂
Dielectric plate (outer diameter φ500 mm, thickness 25 mm, dielectric constant 3.
In 8), 19 is a concentric permanent magnet that forms a magnetic field in the vacuum chamber 11. Its surface magnetic field strength is 2.5 kilogauss. Reference numeral 20 denotes a metal electrode installed on the back surface of the dielectric plate 18, to which high frequency power is applied from a high frequency power supply 25. Two
Reference numeral 1 is an insulator for insulating the metal electrode 20. 22
Is a rectangular waveguide connected to a 2.45 GHz microwave oscillator (not shown) for transporting microwaves, 23 is a ridge for converting the rectangular waveguide 22 into a coaxial waveguide, 2
4 is a plunger for matching the microwave. 25
Is a high frequency power supply.

This coaxial waveguide (16, 17) has a center conductor outer diameter of 2
Dielectric plate 1 after expanding from 1.3mm, outer conductor inner diameter 49mm to center conductor outer diameter 522mm, outer conductor inner diameter 550mm in the direction of microwave propagation in a 45 degree taper
8 is connected to the side surface so as to introduce the microwave into a ring shape and has a door knob shape.

According to the structure of the present embodiment, as shown in FIG. 2A, the microwaves travel in the dielectric plate 18 from the outer circumference toward the center toward the center in a reverse radial manner in a substantially TEM approximation mode.
At this time, the microwave is combined with the surface wave on the surface of the dielectric plate 18, and the surface wave is radiated from the edge of the dielectric plate 18 as shown in FIG. The microwaves travel in the dielectric plate 18 from the periphery toward the center while radiating surface waves, and the energy weakens. However, the microwaves overlap toward the center, so that uniform surface waves can be radiated. it is conceivable that. Here, for example, the TM mode surface wave is coupled when h> (6.79 tan ⁻¹ ε) / {f√ (ε−1)} where h is the thickness of the dielectric plate 18.

Here, f is the microwave frequency, and ε is the dielectric constant of the dielectric plate 18. In this embodiment, SiO
The initial thickness of the dielectric plate 18 of No. ₂ satisfies the above formula, and a value optimized so that the surface wave radiation is uniform in the substrate 4 to be processed was used, but the surface wave is limited to the TM mode. Instead, the thickness may be optimized in consideration of the microwave frequency and the area to be processed in consideration of consumption of the dielectric plate. In the case of the configuration of this embodiment, the target needs to be a dielectric.

The operation of the sputtering apparatus configured as described above will be described below with reference to FIG. First, the vacuum container 11 is evacuated and Ar gas, for example, is introduced from the gas inlet 15 to adjust the pressure to 0.3 mTorr. next,
The microwave power is propagated through the coaxial waveguides (16, 17) by 500 W using the TEM mode as a fundamental wave, and the microwave is introduced in the reverse radial direction from the outer peripheral side surface of the SiO ₂ dielectric plate 18 toward the center. Let This microwave is combined with the surface wave and is uniformly radiated from the edge of the dielectric plate 18 into the vacuum container 11. This surface wave interacts with the magnetic field formed by the permanent magnet 19 to impart a rotational motion to the electrons in the plasma, increase the probability of collision with gas particles, and generate a high-density uniform plasma. The ions in the Ar gas plasma are accelerated by the negative bias potential generated by the high frequency power 25 of 100 W applied to the electrode 20, and the target is the dielectric plate 18 of SiO _2.
The incident beam collides with and sputtering occurs. At this time, a SiO ₂ film could be formed on the substrate 14 to be processed at a film forming rate of 0.15 μm / min and a uniformity of ± 4.3% within a φ420 mm plane.

As described above, according to this embodiment, the dielectric plate 18 which is the target installed as a part of the vacuum container 11 and the outer peripheral side surface of the dielectric plate 18 are formed by the center conductor 16 and the outer conductor 17. A coaxial waveguide for supplying microwave power installed so as to communicate with the air gap, a metal electrode 20 installed on the outer surface of the vacuum plate of the dielectric plate 18, and a metal electrode 2
High frequency power source 25 for applying high frequency power to 0, and permanent magnet 19 for generating a magnetic field on the surface of the dielectric plate in the vacuum container.
And the dielectric plate 18 which is the target.
As the film is evenly sputtered, the uniformity of film formation is good,
In addition, the utilization efficiency of the target can be improved.
Moreover, high-density plasma generation and sputtering can be performed with a high degree of vacuum, and the device size can be reduced.

(Embodiment 2) A second embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a sectional view of the reaction chamber in the second embodiment of the sputtering apparatus according to the present invention.

In FIG. 3, reference numeral 26 is an electromagnet coil which is a magnetic field generating means and forms a magnetic field in the vacuum container 1. Others are the same as those in the first embodiment.

The operation of the sputtering apparatus configured as described above will be described below. It is the same as in the first embodiment that Ar gas or the like is supplied into the vacuum container 1 to radiate microwave surface waves, and high-frequency plasma is generated by applying a high frequency bias to the target. is there. The difference from the first embodiment is the target 18
The point is that the magnetic field formed on the surface is changed from a permanent magnet to an electromagnet coil that is large in size but excellent in magnetic field uniformity. This improves the uniformity of the sputtering process,
The consumption area (erosion) of the target can be uniformly expanded to improve the target utilization efficiency.

(Embodiment 3) A third embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a sectional view of a reaction chamber in the third embodiment of the sputtering apparatus according to the present invention.

In FIG. 4, reference numeral 27 denotes a semi-coaxial cavity resonator having an opening near the center of each of the center conductor and the outer conductor.
Reference numeral 8 is a waveguide for supplying a microwave to the semi-coaxial cavity resonator 27, and other components are the same as those in the first embodiment. A big difference from the first embodiment is that a semi-coaxial cavity resonator 27 is provided to the side surface of the dielectric plate 18 of SiO ₂ which is a target.
Is a point that supplies microwaves in a reverse radial direction. As a result, it is not necessary to enlarge the coaxial waveguide on the taper as in the first embodiment, and the device size can be reduced.

Although the target dielectric plate 18 is SiO ₂ in the first to third embodiments, it may be made of any material that transmits microwaves, such as alumina, BN and Si _3.
N ₄ , Ta ₂ O ₅ , Teflon, or the like may be used. Also,
In the third embodiment, the microwave is supplied to the semi-coaxial cavity resonator 27 by a waveguide, but an antenna inserted in the semi-coaxial cavity resonator may be used.

[0026]

As described above, according to the sputtering apparatus of the first structure of the present invention, the target is uniformly sputtered, so that the film formation is good and the utilization efficiency of the target is improved. In addition, plasma generation and sputtering with high vacuum and high density are possible, and the device size can be reduced.

Further, according to the second structure using the semi-coaxial cavity resonator of the present invention, it is not necessary to expand the coaxial waveguide to a large diameter even when processing a large-area substrate. ,
The size of the device can be reduced.

Further, according to the sputtering method of the present invention, since sputtering is performed with high vacuum and high density plasma, the substrate can be uniformly processed at high speed, and the utilization efficiency of the target can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a reaction chamber in a first embodiment of a sputtering apparatus according to the present invention.

FIG. 2A is an electromagnetic field distribution diagram of surface waves of this embodiment, and FIG. 2B is a schematic diagram showing a state of microwaves traveling in a dielectric plate of this embodiment.

FIG. 3 is a cross-sectional view of a reaction chamber in a second embodiment of the sputtering apparatus according to the present invention.

FIG. 4 is a sectional view of a reaction chamber in a third embodiment of a sputtering apparatus according to the present invention.

FIG. 5 is a sectional view of a reaction chamber in a conventional sputtering processing apparatus.

[Explanation of symbols]

 11 Vacuum Container 12 Vacuum Evacuation System 13 Substrate Holding Table 14 Target Substrate 15 Gas Inlet 16 Central Conductor of Coaxial Waveguide 17 Outer Conductor of Coaxial Waveguide 18 Dielectric Plate 19 Permanent Magnet 20 Metal Electrode 21 Insulator 22 Rectangle Waveguide 23 Ridge converter 24 Plunger 25 High frequency power supply 26 Electromagnetic coil 27 Semi-coaxial cavity resonator 28 Waveguide

Claims (7)

[Claims] 1. A vacuum container having a vacuum evacuation unit and a reaction gas inlet, a substrate holder to be processed installed in the vacuum container, a dielectric plate installed as a part of the vacuum container, A coaxial waveguide installed so that an outer peripheral surface of the dielectric plate communicates with a space formed by a central conductor and an outer conductor of the coaxial waveguide; a microwave power supply unit connected to the coaxial waveguide; A metal electrode installed on the outer surface of the vacuum vessel of the dielectric plate, and means for applying high-frequency power to the metal electrode,
And a means for generating a magnetic field on the surface of the dielectric plate in the vacuum container. 2. The sputtering apparatus according to claim 1, wherein the means for generating a magnetic field is a permanent magnet installed in a metal electrode. 3. The sputtering apparatus according to claim 1, wherein the means for generating a magnetic field is an electromagnet coil installed outside the vacuum container. 4. A vacuum container having a vacuum evacuation unit and a reaction gas introduction port, a substrate holder to be processed placed in the vacuum container, and an opening portion at each of the central portions of the central conductor and the outer conductor, And a semi-coaxial cavity resonator having microwave power supply means, and a dielectric plate installed so as to form a part of a vacuum container in an opening of a central portion of the semi-coaxial cavity resonator and a central portion of an outer conductor. A metal electrode installed on the outer surface of the dielectric plate in the vacuum container, means for applying high-frequency power to the metal electrode, and means for generating a magnetic field on the surface of the dielectric plate inside the vacuum container. Sputtering equipment. 5. The sputtering apparatus according to claim 4, wherein the microwave supplying means to the semi-coaxial cavity resonator is a waveguide coupled to the semi-coaxial cavity resonator. 6. The sputtering apparatus according to claim 4, wherein the microwave supplying means to the semi-coaxial cavity resonator is a microwave radiating antenna inserted in the semi-coaxial cavity resonator. 7. A sputtering method in which a dielectric is sputtered by plasma generated in a vacuum container having a vacuum exhaust means and a reaction gas introducing means, and a dielectric thin film is deposited on a substrate to be processed provided in the vacuum container. It is installed as a part of the vacuum container, by supplying microwave power by a coaxial waveguide in a reverse radial direction from the outer peripheral side of the dielectric plate having a metal electrode on the vacuum container outer plane toward the center, Plasma generated by the interaction between the surface wave of the microwave radiated from the surface of the dielectric plate and the magnetic field formed in the radiation region of the surface wave, and the bias potential of the high frequency power supplied to the metal electrode of the dielectric plate. And a method of sputtering a dielectric plate to deposit a dielectric thin film on a substrate to be processed.