JP2004269928A - Method and apparatus for manufacturing dielectric thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a dielectric thin film having superior optical and electrical characteristics, with a comparatively high film-forming speed, while alleviating damage on the film due to high-energy particles, and to provide a manufacturing apparatus therefor. <P>SOLUTION: In a process of manufacturing a dielectric thin film in an apparatus having a film-forming region and an oxidizing region for the dielectric thin film, by forming a thin film on the substrate through sputtering a target installed on a cathode in the film-forming region, then moving the substrate, and oxidizing the thin film with an oxidizing source in the oxidizing region, the manufacturing method comprises arranging one or more film-forming regions, placing one pair of the targets separately at a space so as to face each other in each film-forming region, sputtering each other between the one pair of targets, and producing the dielectric thin film on the substrate placed on a side of the space. The manufacturing method has comparatively high film-forming speed, alleviates the damage on the film due to the high-energy particles, and provides the dielectric thin film having the superior optical and electrical characteristics. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for manufacturing a dielectric thin film.
[0002]
[Prior art]
As a method for producing a dielectric thin film such as an oxide thin film, a production method by reactive sputtering in which an active gas is introduced into a sputtering space, and a sputter material obtained from a target is reacted with the active gas to deposit a compound film, is used. Are known.
[0003]
In this reactive sputtering, usually, the cathode is arranged to face the substrate, so that 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, there has been proposed a manufacturing method by facing target type sputtering in which a pair of targets arranged so as to face each other with a space therebetween generates a magnetic field in the vertical direction and performs Penning discharge. (For example, see Patent Document 1).
[0005]
According to the facing target 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. This enabled the production of thin films with low damage.
[0006]
In the normal sputtering, only an inert gas is used as a sputtering gas. In the reactive sputtering, an active gas is added to the inert gas as a sputtering gas, and a reactant of solid particles and an active gas that jumps out of a target. Is formed.
[0007]
In the case of an oxide thin film, an abnormal arc discharge frequently occurs because the target surface is oxidized because oxygen gas is simultaneously introduced into the sputtering gas as an active gas, and furthermore, a dielectric thin film is deposited on a deposition-preventing plate or the like. There is a possibility that.
[0008]
In order to eliminate the abnormal arc discharge, conventionally, it has been proposed to apply an AC electric field having a phase difference of 180 degrees to the two opposing targets (for example, see Patent Document 2).
[0009]
By the way, when a discharge using an electrode such as an ion gun or DC plasma is used as an oxidizing source of the oxygen gas introduced in the production of the oxide thin film, an unreacted oxidizing gas diffuses near the target and oxidizes the target surface. Then, the film forming speed 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 a thin film is formed in the film formation region, and then the substrate is moved to the oxidation region and oxidized. (For example, see Patent Documents 3 and 4).
[0011]
According to this method, since the film formation step and the oxidation step are performed separately, the dielectric thin film can be manufactured at a relatively high speed without oxidizing gas oxidizing the target surface. .
[0012]
[Patent Document 1]
Japanese Patent Publication No. Sho 62-56575 (page 3)
[0013]
[Patent Document 2]
JP-A-11-29862 (page 1)
[0014]
[Patent Document 3]
Japanese Patent No. 2695514
[Patent Document 4]
JP-A-6-291375
[Problems to be solved by the invention]
However, among the reactive sputtering methods, the above-described method using the opposed target sputtering method requires that a magnetic field be generated in the vertical direction by Penning discharge to confine high-energy particles. There is a disadvantage that the distance is limited.
[0017]
Further, in order to eliminate abnormal arc discharge, in the above-mentioned conventional method of applying an AC electric field having a phase difference of 180 degrees to two opposing targets, for example, when TiO ₂ is produced, an anatase-type oriented crystal is used. This method is not suitable for an optical film that requires an amorphous structure among the dielectric thin films because it becomes a film.
[0018]
In order to prevent abnormal arc discharge, if the amount of oxygen introduced to the extent that the target surface is not oxidized is reduced, increasing the deposition rate will result in insufficient oxidation of the dielectric thin film deposited on the substrate of interest, such as band Optical multilayer films such as a pass filter and a low-pass filter have a problem that a film having inferior characteristics is produced.
[0019]
On the other hand, in the above-described conventional method of manufacturing a dielectric film, in which a film formation region and an oxidation region are separately provided, a thin film is formed in the film formation region, and the substrate is moved to the oxidation region and oxidized, the cathode in the film formation region is formed. There is a disadvantage that the thin film formed on the substrate is damaged by high-energy particles distributed in the vertical direction from the cathode, which are arranged to face the substrate.
[0020]
In view of the above problems, the present invention provides a method and apparatus for manufacturing a dielectric thin film having a relatively high film forming rate, reducing damage caused by high-energy particles, and having good optical and electrical characteristics. The task is to provide
[0021]
[Means for Solving the Problems]
In order to solve the above problems, a method for manufacturing a dielectric thin film according to the present invention has a film forming region and an oxidized region of a dielectric thin film, and sputtering a target provided on a cathode in the film forming region. After forming a thin film on a substrate, in a method of manufacturing a dielectric thin film in which the substrate is moved and the thin film is oxidized by an oxidation source in the oxidized region, one or more film forming regions are provided, The method is characterized in that a dielectric thin film is manufactured on a substrate arranged on the side of the space by sputtering using a pair of targets arranged opposite to each other with a space therebetween.
[0022]
According to this configuration, when the film forming step and the oxidizing step for one substrate are sequentially performed in different regions, a dielectric thin film is efficiently manufactured using a pair of sputtering cathodes that are opposed to each other in the film forming region. can do.
[0023]
In addition, the magnetron discharge is generated independently in each target by making the magnetic field generated on each surface of the pair of targets orthogonal to the electric field generated by applying an AC electric field to the surface of each target. It becomes possible to do.
[0024]
Further, by making the alternating electric field applied to the target surface 180 degrees out of phase, the oxidized dielectric thin film is prevented from adhering and depositing on other than the substrate, and as a result, abnormal arc discharge is generated. Can be solved.
[0025]
If oxygen radicals generated by microwave-excited plasma such as electron cyclotron resonance (ECR) plasma are used for the oxidation source, discharge can be performed without using electrodes.
[0026]
The apparatus for manufacturing a dielectric thin film according to the present invention includes a cathode capable of generating a magnetic field and a surface capable of generating a magnetron discharge on each surface of the pair of targets. And an AC power supply for generating an electric field by applying an AC electric field having a phase shift of 180 degrees.
[0027]
The manufacturing apparatus includes a cathode capable of generating a magnetron discharge between the magnetic field generated on the surface of each of the pair of targets, and a magnetic field for preventing an abnormal arc discharge. An AC power source for generating an electric field by applying an AC electric field 180 degrees out of phase to each surface of the pair of targets can be provided.
[0028]
When oxidizing the dielectric thin film, in order to utilize oxygen radicals, an oxygen source provided with a mechanism for generating microwave-excited plasma such as electron cyclotron resonance (ECR) plasma may be provided.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is an example of an embodiment of a dielectric thin film manufacturing apparatus according to the present invention.
[0030]
1 is a vacuum chamber of the apparatus for producing a dielectric thin film according to the present invention. The vacuum chamber 1 is evacuated by an exhaust pipe 2.
At the center of the vacuum chamber 1, a rotatable cylindrical substrate holder 3 is supported by a rotating shaft 4 while being separated from the inner wall of the vacuum chamber 1. A substrate 5 is mounted on 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]
The space between the surface of the substrate holder 3 and the inner wall of the vacuum chamber 1 is divided into a film forming region 7 and an oxidized region 8 with a deposition preventing plate 6 therebetween.
[0033]
In the present embodiment, two film formation regions 7 are provided. In each film forming region 7, a gas inlet 9 for introducing a sputtering gas is provided inside the film forming region 7. A pair of cathodes 11 each having a target 10 attached thereto are arranged inside each film formation region 7 so as to face each other. A magnet (not shown) is provided inside each of the pair of cathodes 11, and an AC power supply (not shown) for applying an AC electric field having a phase shifted by 180 degrees to two opposing targets is connected. Have been.
[0034]
Therefore, 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 a film can be formed unlike the conventional facing target type sputtering in which a magnetic field is generated in the vertical direction and Penning discharge is performed. The region is not limited to the distance between the targets 10, and a sufficient film formation region can be secured.
[0035]
In the oxidized region 8, an oxygen inlet 12 is provided for introducing oxygen into the oxidized region 8. Inside the oxidized 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 provided through a microwave introduction window 14. Is connected to a microwave antenna 16 inside the vacuum chamber 1.
[0036]
Therefore, a discharge can be performed without using an electrode as an oxidation source, so that there is no inconvenience that high-energy particles are accelerated and enter the substrate 5 to damage the thin film during oxidation.
[0037]
【Example】
Hereinafter, a specific example will be described using the apparatus for manufacturing a dielectric thin film described with reference to FIG.
[0038]
The Si wafer substrate and the glass substrate on which the thermal oxide film was formed at 20 ° were attached to the substrate holder 3, and the vacuum chamber 1 was evacuated to 5 × 10 ⁻⁵ Pa. 50 sccm of argon gas was introduced from the gas inlet 9, and 20 sccm of oxygen gas + 40 sccm of argon gas were respectively 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, an AC power of 2 kW and 40 kHz was applied to the cathode 11 on which the 5 inch × 18 inch Si target 10 was attached. .
[0040]
At the moment when the substrate is in the film formation region 7, a 0.5 nm thick Si thin film in a substantially metallic state is formed 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 having almost no absorption was obtained.
[0042]
An Al electrode was formed on the manufactured SiO ₂ film by heating evaporation, and CV measurement was performed.
[0043]
As compared with the result of the thermal oxide film, the flat band shift was 0.04 V, which was a good characteristic.
[0044]
Next, 40 sccm of oxygen gas + 40 sccm of argon gas were introduced from the gas inlet 9, and an SiO ₂ film having the same thickness as described above was formed in the oxidation region 8 without operating the oxidation source. The same 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, and 40 sccm of oxygen gas + 40 sccm of argon gas are introduced from the gas inlet 9. An SiO ₂ film having the same thickness as above was formed without operating the source.
[0046]
The optical characteristics were as good as the above, but the flat band shift was increased to 1.0V.
[0047]
FIG. 3 shows the results of plotting the flat band shift of the SiO ₂ film formed by the three methods with respect to the film thickness.
[0048]
Comparing the result of the film formation by the manufacturing method according to the present invention performed first and the result of the film formation performed by “facing cathode + reactive sputtering” performed second, the present invention is superior when the film thickness is the same. Characteristics were obtained.
[0049]
Further, in the present invention, the film formation rate is high, and the processing time can be shortened.
[0050]
In the case of “parallel plate cathode + reactive sputtering” shown in FIG. 2, the film formation rate is faster than that of the above “opposite cathode + reactive sputtering”, but the flat band shift is large, so that the damage to the base is the largest. Understand.
[0051]
【The invention's effect】
As is apparent from the above description, the present invention has a film forming region and an oxidized region, and a pair of sputtering cathodes are arranged opposite to each other in the film forming region. In addition, 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 area where a film can be formed is not limited to the distance between the targets, and a sufficient area for film formation can be secured.
[0053]
Furthermore, by applying an alternating electric field 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 an apparatus for manufacturing a dielectric thin film according to the present invention, in which a) is a top view of the manufacturing apparatus and b) is a side view of the manufacturing apparatus.
FIG. 2 is a configuration diagram of a conventional apparatus for manufacturing a dielectric thin film having a parallel plate cathode, wherein a) is a top view of the apparatus and b) is a side view of the apparatus.
FIG. 3 is a diagram showing a relationship between a SiO ₂ film thickness and a flat band shift.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vacuum tank 2 Exhaust pipe 3 Substrate holder 4 Rotating shaft 5 Substrate 6 Deposition plate 7 Deposition area 8 Oxidation area 9 Gas inlet 10 Target 11 Cathode 12 Oxygen inlet 13 Magnetic circuit 14 Microwave introduction window 15 Waveguide 16 Microwave antenna

Claims (6)

It has a film formation region of a dielectric thin film and an oxidized region. In this film formation region, a target provided on a cathode is sputtered to form a thin film on a substrate, and then the substrate is moved to oxidize in the oxidized region. In a method of manufacturing a dielectric thin film in which the thin film is oxidized by a source, one or more of the film formation regions are provided, and a pair of targets arranged to face each other with a space in each film formation region is used, A method for producing a dielectric thin film, comprising: producing a dielectric thin film on a substrate disposed on a side of the space by sputtering. The cathode generates a magnetic field in a horizontal direction with respect to each surface of the pair of targets, and independently applies an AC electric field having a phase shift of 180 degrees to each surface to independently generate a magnetic field in each of the targets. 2. The method for producing a dielectric thin film according to claim 1, wherein a magnetron discharge is generated. 3. The method for producing a dielectric thin film according to claim 1, wherein the oxidation source according to claim 1 utilizes oxygen radicals generated by microwave-excited plasma. An oxidizing source comprising a dielectric thin film deposition region and an oxidation region, a substrate and a cathode having a sputtering target provided in the deposition region, and an oxidation source for oxidizing a film formed on the substrate in the oxidation region; In the apparatus for manufacturing a dielectric thin film provided with a pair of targets, one or more of the above-mentioned film forming regions are provided, and a pair of targets are disposed in each film forming region so as to face each other with a space therebetween. A substrate holder on which a substrate can be arranged on a side of the space. In order to generate a magnetron discharge on each surface of the pair of targets, a cathode capable of generating a magnetic field, and an AC electric field 180 degrees out of phase applied to each surface of the pair of targets to generate an electric field. 5. The apparatus for producing a dielectric thin film according to claim 4, further comprising an AC power supply for generating the voltage. 6. The dielectric thin film according to claim 1, wherein the oxidation source according to claim 4 includes a microwave-excited plasma generating mechanism for utilizing oxygen radicals. Manufacturing equipment.

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