JP4480336B2 - Dielectric thin film manufacturing method and manufacturing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dielectric thin film manufacturing method and manufacturing apparatus.
[0002]
[Prior art]
As a method of manufacturing a dielectric thin film such as an oxide thin film, there is a manufacturing method by reactive sputtering in which an active gas is introduced into a sputtering space and a sputtering material obtained from a target is reacted with the active gas to deposit a compound film. Are known.
[0003]
In this reactive sputtering, since the cathode is usually arranged opposite to the substrate, many particles having high energy are distributed in the vertical direction with respect to the target provided on the cathode. There is a problem that the high-energy particles damage the dielectric thin film formed on the substrate.
[0004]
Conventionally, in order to solve this problem, a manufacturing method by facing target type sputtering in which a pair of targets arranged so as to face each other across a space is subjected to Penning discharge by generating a magnetic field in the vertical direction has been proposed. (For example, refer to Patent Document 1).
[0005]
According to this facing target type sputtering, particles having high energy can be confined between a pair of targets by the magnetic field generated in the vertical direction, so that the particles can be prevented from entering the substrate. It was possible to manufacture a thin film with low damage.
[0006]
In normal sputtering, only an inert gas is used as a sputtering gas, but in the reactive sputtering described above, an active gas is added to the inert gas as a sputtering gas, and a reaction product of solid particles and active gas popping out from the target. It is characterized by forming a film.
[0007]
In the case of an oxide thin film, oxygen gas as an active gas is simultaneously introduced into the sputtering gas, so that the target surface is oxidized, and furthermore, a dielectric thin film is deposited on the deposition plate, etc., so abnormal arc discharge frequently occurs. There is a risk.
[0008]
In order to eliminate this abnormal arc discharge, conventionally, it has been proposed to apply an alternating electric field whose phase is shifted by 180 degrees to the two opposing targets (see, for example, Patent Document 2).
[0009]
By the way, when a discharge using an electrode such as an ion gun or a DC plasma is used as an oxygen gas oxidation source introduced in the production of the oxide thin film, unreacted oxidation gas diffuses in the vicinity of the target and oxidizes the target surface. And the film formation rate is reduced.
[0010]
Conventionally, in order to solve such problems, a method has been proposed in which a film formation region and an oxidation region are separately provided in the same space, and after a thin film is formed in the film formation region, the substrate is moved to the oxidation region and oxidized. (For example, see Patent Document 3 and Patent Document 4).
[0011]
According to this method, since the film forming process and the oxidizing process are performed separately, the oxidizing gas does not oxidize the target surface, and it is possible to manufacture the dielectric thin film at a relatively high speed. .
[0012]
[Patent Document 1]
Japanese Examined Patent Publication No. 62-56575 (page 3)
[0013]
[Patent Document 2]
JP 11-29862 A (first page)
[0014]
[Patent Document 3]
Japanese Patent No. 2695514 [0015]
[Patent Document 4]
JP-A-6-291375 [0016]
[Problems to be solved by the invention]
However, among the reactive sputtering, the manufacturing method using the above-described facing target type sputtering requires that a high-energy particle be confined by generating a magnetic field in the vertical direction by Penning discharge. There was an inconvenience that the distance between them was limited.
[0017]
Further, in order to eliminate abnormal arc discharge, in the above-described conventional method in which an alternating electric field whose phase is shifted by 180 degrees is applied to two opposing targets, for example, when manufacturing TiO ₂ , crystals oriented in an anatase type Since it becomes a film, it is a method unsuitable for an optical film in which an amorphous structure is a necessary condition among the dielectric thin films.
[0018]
In order to prevent abnormal arc discharge, if the amount of oxygen introduced is reduced to such an extent that the target surface is not oxidized, increasing the film formation rate will result in insufficient oxidation of the dielectric thin film formed on the critical substrate. The optical multilayer film such as a pass filter or a low-pass filter has a problem that a film having poor characteristics is manufactured.
[0019]
On the other hand, in the above conventional dielectric film manufacturing method in which the film formation region and the oxidation region are provided separately, a thin film is formed in the film formation region, and the substrate is moved to the oxidation region to be oxidized, the cathode in the film formation region Has a disadvantage that the thin film formed on the substrate is damaged by the high-energy particles arranged opposite to the substrate and distributed vertically from the cathode.
[0020]
Accordingly, in view of the above-described problems, the present invention provides a method and apparatus for manufacturing a dielectric thin film having a relatively high film formation rate, reducing damage caused by high-energy particles, and having good optical and electrical characteristics. It is an issue to provide.
[0021]
[Means for Solving the Problems]
In order to solve the above-described problems, in the method for manufacturing a dielectric thin film according to the present invention, the vacuum chamber has a film formation region and an oxidation region of a Si thin film in a metal state, and is provided on the cathode in this film formation region. In the method of manufacturing a dielectric thin film, the target is sputtered to form a thin film on the substrate, and then the substrate is moved to oxidize the thin film with an oxidation source in the oxidation region. A pair of targets are arranged opposite to each other with a space in each film formation region, and a magnetic field is generated on the surface of each of the pair of opposed targets by the cathode, and on each surface of the pair of targets. by applying the deviation AC field was a 180 degree phase, to generate a magnetron discharge independently in each of the above target, further, rotatable substrate holder spaced apart from the inner wall of the vacuum chamber The substrate attached to the outer periphery, is rotated as the substrate is positioned on the side of the space, by sputtering, and forming a dielectric thin film on a substrate located on the side.
[0022]
According to this configuration, when a film formation process and an oxidation process for one substrate are sequentially performed in different regions, a dielectric thin film is efficiently manufactured by using a pair of sputtering cathodes arranged opposite to each other in the film formation region. can do.
[0023]
In addition, magnetron discharge is generated independently at each target by making the magnetic field generated on the surface of each of the pair of targets orthogonal to the electric field generated by applying an alternating electric field to the surface of each target. It becomes possible to make it.
[0024]
Furthermore, by making the AC electric field applied to the target surface 180 degrees out of phase, it is possible to prevent an oxidized dielectric thin film from adhering to and deposit on the substrate, resulting in the occurrence of abnormal arc discharge. Can be solved.
[0025]
If oxygen radicals generated by microwave-excited plasma such as electron cyclotron resonance (ECR) plasma are used as the oxidation source, discharge can be performed without using electrodes.
[0026]
In the dielectric thin film manufacturing apparatus according to the present invention, the vacuum chamber includes a film formation region and an oxidation region of a Si thin film in a metal state, and a substrate and a cathode having a sputtering target are provided in the film formation region. In the dielectric thin film manufacturing apparatus provided with an oxidation source for oxidizing the film formed on the substrate in the oxidation region, one or more of the film formation regions are provided, and each film formation region is separated from each other by a space. A pair of targets arranged so as to face each other and a substrate holder that can be rotated apart from the inner wall of the vacuum chamber, and a substrate attached to the outer periphery of the substrate holder is positioned on the side of the space. as described above, the substrate holder is rotated, by sputtering, Ma in the is configured to form a dielectric thin film on a substrate located on the side, the oppositely disposed pair of targets each surface In order to generate a netron discharge, a cathode capable of generating a magnetic field on the surface of each of the pair of targets, and an alternating electric field that is 180 degrees out of phase are applied to the surfaces of each of the pair of targets. An AC power source for generating is provided .
[0027]
In the manufacturing apparatus, a magnetron discharge is generated between the pair of targets and a magnetic field generated on each surface of the target, and a magnetic field can be generated in order to prevent abnormal arc discharge, An AC power source that generates an electric field by applying an AC electric field that is 180 degrees out of phase to each surface of the pair of targets can be provided.
[0028]
Moreover, when oxidizing a dielectric thin film, in order to utilize an oxygen radical, you may provide what provided the generation | occurrence | production mechanism of microwave excitation plasmas, such as an electron cyclotron resonance (ECR) plasma, as said oxygen source.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an example of an embodiment of a dielectric thin film manufacturing apparatus according to the present invention.
[0030]
Reference numeral 1 denotes a vacuum chamber of a dielectric thin film manufacturing apparatus according to the present invention. The vacuum chamber 1 is evacuated by the exhaust pipe 2.
At the center of the vacuum chamber 1, a cylindrical substrate holder 3 that is spaced apart from the inner wall of the vacuum chamber 1 and is rotatable is supported by a rotation shaft 4. A substrate 5 is attached to the outer periphery of the substrate holder 3.
[0031]
In the present embodiment, the substrate holder 3 is cylindrical, but the substrate may be attached to a flat substrate holder, and is not limited to a cylindrical one.
[0032]
A space between the surface of the substrate holder 3 and the inner wall of the vacuum chamber 1 is divided into a film formation region 7 and an oxidation region 8 with an adhesion preventing plate 6 therebetween.
[0033]
In the present embodiment, two film formation regions 7 are provided. In each film formation region 7, a gas introduction port 9 for introducing a sputtering gas is provided inside the film formation region 7. A pair of cathodes 11 to which targets 10 are attached are arranged inside each film formation region 7 so as to face each other. Each of the pair of cathodes 11 is provided with a magnet (not shown) inside, and an AC power source (not shown) for applying an AC electric field whose phase is shifted by 180 degrees is connected to two opposing targets. Has been.
[0034]
Accordingly, when an AC electric field is applied to the cathode 11, a magnetron discharge is generated independently on the surface of the target 10, so that film formation is possible unlike conventional counter target type sputtering in which a magnetic field is generated in the vertical direction to perform Penning discharge. The area is not limited to the distance between the targets 10, and a sufficient film formation area can be secured.
[0035]
In the oxidation region 8, an oxygen inlet 12 is provided to introduce oxygen into the oxidation region 8. Inside the oxidation region 8, a magnetic circuit 13 is provided. In order to generate a microwave-excited plasma such as an electron cyclotron resonance (ECR) plasma by the magnetic circuit 13, the vacuum chamber 1 is passed through the microwave introduction window 14. The external waveguide 15 is connected to the microwave antenna 16 inside the vacuum chamber 1.
[0036]
Therefore, since discharge without using an electrode as an oxidation source is possible, there is no inconvenience that high-energy particles are accelerated and incident on the substrate 5 to cause damage when the thin film is oxidized.
[0037]
【Example】
Hereinafter, specific examples will be described using the dielectric thin film manufacturing apparatus described in FIG.
[0038]
The Si wafer substrate and glass substrate on which 20 mm of thermal oxide films were formed were attached to the substrate holder 3, and the vacuum chamber 1 was evacuated to 5 × 10 ⁻⁵ Pa. Argon gas 50 sccm was introduced from the gas inlet 9, and oxygen gas 20 sccm + argon gas 40 sccm was introduced from the oxygen inlet 12, and the pressure in the vacuum chamber 1 was set to 0.5 Pa.
[0039]
After rotating the substrate holder 3 at 120 rpm, a microwave power of 2 kW was applied from the microwave antenna 16 and simultaneously, a 2 kW, 40 kHz AC power was applied to the cathode 11 on which the Si target 10 of 5 inches × 18 inches was attached. .
[0040]
At the moment when the substrate is in the film formation region 7, a substantially metallic Si thin film is deposited to a thickness of 0.5 nm on the substrate, and at the moment when the substrate is in the oxidation region 8, the thin film on the substrate is oxidized.
[0041]
When the SiO ₂ thin film formed by the above method was analyzed, a good optical thin film with almost no absorption could be obtained.
[0042]
An Al electrode was formed on the manufactured SiO ₂ film by heating vapor deposition, and CV measurement was performed.
[0043]
When compared with the result with the thermal oxide film, the flat band shift was 0.04 V, and good characteristics could be obtained.
[0044]
Next, oxygen gas 40 sccm + argon gas 40 sccm was introduced from the gas inlet 9, and an SiO ₂ film having the same film thickness as described above was formed in the oxidation region 8 without operating the oxidation source. Equivalent good characteristics were obtained, but the flat band shift increased to 0.1V.
[0045]
Further, as shown in FIG. 2, the target 10 of the manufacturing apparatus of FIG. 1 is arranged in parallel so as to face the substrate 5, oxygen gas 40 sccm + argon gas 40 sccm is introduced from the gas inlet 9, and oxidation is performed in the oxidation region 8. A SiO ₂ film having the same film thickness as described above was formed without operating the source.
[0046]
The optical characteristics were as good as those described above, but the flat band shift increased to 1.0V.
[0047]
FIG. 3 shows the result of plotting the flat band shift of the SiO ₂ film formed by the three methods with respect to the film thickness.
[0048]
When the film formation result by the manufacturing method according to the present invention performed first and the film formation result by the second “opposite cathode + reactive sputtering” are compared, the present invention is superior when the film thickness is the same. Characteristics were obtained.
[0049]
In the present invention, the deposition rate is high and the processing time can be shortened.
[0050]
Note that the “parallel plate cathode + reactive sputtering” shown in FIG. 2 has a higher deposition rate than the above “opposite cathode + reactive sputtering”, but the flat band shift is large, so the damage to the substrate is the greatest. Recognize.
[0051]
【The invention's effect】
As is clear from the above description, the present invention has a film formation region and an oxidation region, and a pair of sputtering cathodes are arranged opposite to each other in the film formation region, so that the film formation rate is relatively high, and It is possible to reduce the damage caused by high energy particles and to manufacture a dielectric thin film having good optical and electrical characteristics.
[0052]
In addition, since a magnetron discharge can be generated on each surface of the pair of targets, the filmable region is not limited to the distance between the targets, and a sufficient film formation region can be secured.
[0053]
Furthermore, by applying an AC electric field that is 180 degrees out of phase to the surface of each of the pair of targets in the film formation region, abnormal arc discharge can be prevented.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a dielectric thin film manufacturing apparatus according to the present invention, wherein a) is a top view of the manufacturing apparatus, and b) is a side view of the manufacturing apparatus.
FIGS. 2A and 2B are configuration diagrams of a conventional dielectric thin film manufacturing apparatus provided with a parallel plate cathode, wherein a) is a top view of the manufacturing apparatus, and b) is a side view of the manufacturing apparatus.
FIG. 3 is a diagram showing the relationship between SiO ₂ film thickness and flat band shift.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Exhaust pipe 3 Substrate holder 4 Rotating shaft 5 Substrate 6 Deposition plate 7 Deposition region 8 Oxidation region 9 Gas introduction port 10 Target 11 Cathode 12 Oxygen introduction port 13 Magnetic circuit 14 Microwave introduction window 15 Waveguide 16 Microwave antenna

Claims (4)

A vacuum chamber has a film formation region and an oxidation region of a Si thin film in a metal state, and after sputtering a target provided on the cathode in this film formation region to form a thin film on the substrate, the substrate is moved. In the method of manufacturing a dielectric thin film, wherein the thin film is oxidized by an oxidation source in the oxidation region,
One or more of the film formation regions are provided, a pair of targets are arranged opposite to each other with a space in each film formation region, and a magnetic field is generated on the surface of each of the pair of targets arranged opposite to each other by the cathode. In addition, by applying an alternating electric field that is 180 degrees out of phase to the surface of each of the pair of targets, a magnetron discharge is independently generated in each of the targets,
Further, the substrate is attached to the outer periphery of a substrate holder that can be rotated away from the inner wall of the vacuum chamber, and the substrate is rotated so that the substrate is positioned on the side of the space, and sputtering is performed to position the substrate on the side. A dielectric thin film is formed on a substrate to be manufactured. Method for producing a dielectric thin film according to claim 1 Symbol placement, wherein the oxidizing source using oxygen radicals generated by microwave-excited plasma. A vacuum chamber includes a film-formation region and an oxidation region of a Si thin film in a metal state, a substrate and a cathode having a sputtering target are provided in the film-formation region, and the oxidation region is formed on the substrate. In a dielectric thin film manufacturing apparatus provided with an oxidation source for oxidizing a film,
One or more film formation regions are provided, and each film formation region has a pair of targets arranged so as to face each other with a space therebetween, and a substrate holder that is rotatable away from the inner wall of the vacuum chamber. Then, a dielectric thin film is formed on the substrate located on the side by rotating and sputtering the substrate holder so that the substrate attached to the outer periphery of the substrate holder is located on the side of the space. is configured to,
In order to generate a magnetron discharge on the surface of each of the pair of targets arranged opposite to each other, a cathode capable of generating a magnetic field on the surface of each of the pair of targets, and 180 on each surface of the pair of targets. An apparatus for producing a dielectric thin film, comprising: an AC power supply that generates an electric field by applying an AC electric field that is out of phase . 4. The dielectric thin film manufacturing apparatus according to claim 3, wherein the oxidation source has a mechanism for generating microwave-excited plasma in order to use oxygen radicals.

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