JPH0657422A - Dc magnetron sputtering device - Google Patents

Abstract

PURPOSE:To enhance the quality of a protective film by obviating the generation of abnormal electric discharge and preventing dust generation and to improve productivity by increasing the speed of forming the protective film in the production of the protective film for a magneto-optical disk, etc., by the DC magnetron sputtering device. CONSTITUTION:This DC magnetron sputtering device has a target 1 which is mounted on a rear plate 2, a magnetic field generator 14 which generates magnetic fields on the surface of this target, a cathode 3 which is mounted with the rear plate and a DC power source 7 which supplies direct electric power to this cathode. Further, an insulator 4 covering the circumferential surface of the target 1 and the surface peripheral edge of the rear plate 2 is provided. The magnetic field generator 14 is constituted of a magnet having the effect of sputtering the entire front surface of the target. The spacing between the target and the insulator is preferably <=0.5mm and the diameter of the target 150 to 260mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC magnetron sputtering apparatus, and more particularly to a DC magnetron sputtering apparatus for producing a protective film produced on, for example, a magneto-optical disk at high speed and with high quality.

[0002]

2. Description of the Related Art The structure of a film formed in a conventional magneto-optical disk will be described with reference to FIG. In the configuration example of FIG. 5A, the protective film 52, the recording film 53, and
Each film is stacked in the order of the protective film 52. In the configuration example of FIG. 5B, each film is laminated on the substrate 51 in the order of the protective film 52, the recording film 53, the protective film 52, and the reflective film 54. Polycarbonate, glass, or the like is used for the substrate 51. For the recording film 53, an alloy composed of a rare earth metal and a transition metal, such as TbFeCo or DyFeCo, is used. Since the recording film 53 is very easily oxidized, it is protected by the protective film 52 having an antioxidant function. Further, the protective film 52 is optically transparent, and C / N (ca
Improve the rrier / noise) ratio. The protective film is also called as a dielectric film or an enhanced film. As the material of the protective film, for example, SiN, SiO, AlN, TaO or the like is used. The reflective film 54 is a film that reflects laser light, and its material is Al, AlTi, Au, or the like.

As a method of forming the protective film 52, the RF (high frequency) magnetron sputtering method and the DC method have been used in principle.
There are two types of (DC) magnetron sputtering. Each sputtering method will be described below. RF now
Since the magnetron sputtering method is the mainstream, this will be described first, and the differences in the DC magnetron sputtering method will be described. An example of a SiN film will be described as the protective film.

FIG. 6 shows an apparatus for implementing the RF magnetron sputtering method. 61 is a back plate, and 62 is a back plate 6.
It is a target fixed on top of 1. Target 62
Is sintered SiN or high-purity Si. 63 is
It is a cathode having a magnet 64 built therein. The target 62 is attached to the cathode 63 via the back plate 61. Reference numeral 65 is a reaction chamber whose inside can be made into a required vacuum state. The cathode 63 is fixed to the reaction chamber 65 via an insulator 66. Inside the target 63, the target 6
To cool 3, cooling water is supplied as indicated by arrow A and discharged as indicated by arrow B. The cathode 63 has a matching circuit 6
7, for example, a 13.56 MHz high frequency power supply 68
Powered by. A shield 69 is arranged around the cathode 63 so that the supplied electric power is concentrated on the target 62. Ar gas and N ₂ gas are passed through valves 70 and 71, respectively, and are supplied to the reaction chamber 65 through corresponding supply pipes.
Will be introduced in. The flow rates of Ar gas and N ₂ gas are controlled by a flow meter (not shown). The Ar gas and the N ₂ gas introduced into the reaction chamber 65 are supplied to the valve 72 and the orifice 73.
Exhausted through. The pressure inside the reaction chamber 65 is 7
Orifice 73 to obtain the desired pressure, measured at 4
The emission amount is adjusted by. As described above, the target 62 is RF magnetron sputtered in the atmosphere of Ar gas and N ₂ gas, so that SiN is formed on the surface of the substrate 75.
Make a membrane.

FIG. 7 shows an apparatus for implementing the DC magnetron sputtering method. In the configuration shown in FIG. 7, elements substantially the same as the elements shown in FIG. 6 are designated by the same reference numerals, and description thereof will be omitted. The target 62 is P, B, S
It is formed of Si doped with at least one of b, As, and Ga. DC power is supplied to the cathode 63 from a DC power supply 77 via an arc extinguishing circuit 76. In the atmosphere of Ar gas and N ₂ gas, target 62
A SiN film is formed on the surface of the substrate 75 by C magnetron sputtering.

[0006]

In the conventional DC magnetron sputtering method, as shown in FIG. 6, the plasma discharge region 78 is formed in the limited space between the substrate 75 and the target 62, and the inside of the reaction chamber 65 is formed. It does not spread over the entire space 79. Therefore, the deposition rate of the SiN film can be increased by increasing the power supply or shortening the distance between the substrate 75 and the target 62.

On the other hand, the RF magnetron sputtering method cannot increase the deposition rate of the SiN film. That is, in the RF magnetron sputtering method,
Since the generated plasma spreads over the entire inner space 79 of the reaction chamber 65, the substrate 75 is directly exposed to the plasma.
In this state, if the supply power is increased or the distance between the substrate 75 and the target 62 is shortened in order to increase the film formation speed, the probability that ions, electrons, etc. will enter the substrate 62 increases, and the temperature of the substrate rises. However, the internal stress of the substrate increases. When the substrate temperature increases, the problem of softening the substrate occurs, and when the internal stress increases, the problem of film peeling occurs. For this reason, in the RF magnetron sputtering method, it is not possible to increase the power supply and to shorten the distance between the substrate 75 and the target 62, so that S
The film forming rate of the iN film cannot be increased.

As described above, the DC magnetron sputtering method is superior to the RF magnetron sputtering method in that
It has a feature that the film forming rate of the N film, that is, the protective film can be increased.

However, the DC magnetron sputtering method has a problem that abnormal discharge occurs and dust is generated. In FIG. 8, the flow rate of Ar is 50 SCCM, the flow rate of N ₂ is 40 SCCM, and the distance between the target 62 and the substrate 75 is 145 m.
The number of abnormal discharges per minute is shown under the film forming condition that m and the power supplied to the cathode 62 are 3 KW. As described above, the arc extinguishing circuit 76 is provided for the purpose of reducing abnormal discharge, but the abnormal discharge cannot be completely eliminated.

In the conventional DC magnetron sputtering apparatus, when an abnormal discharge occurs, the power supply is automatically stopped for a predetermined time in order to reduce the occurrence of the abnormal discharge. As a result, the power supply is automatically limited, and the film forming rate is limited.

An object of the present invention is to prevent the generation of dust by preventing abnormal discharge in the production of a protective film for a magneto-optical disk or the like by using the DC magnetron sputtering method, and to improve the quality of the protective film. Compared with the RF magnetron sputtering method, the film forming rate of the protective film can be increased under the same or lower film forming conditions, and the productivity can be improved.
It is to provide a C magnetron sputtering apparatus.

[0012]

A DC magnetron sputtering apparatus according to the present invention comprises a target mounted on a back plate, a magnetic field generator for generating a magnetic field on the surface of the target, a cathode for mounting the back plate, and this cathode. Has a direct current power supply for supplying direct current power to the target, and further has an insulator covering the peripheral surface of the target and the peripheral portion of the surface of the back plate, and the magnetic field generator is composed of a magnet having a function of sputtering the entire surface of the target. It In the above structure, the distance between the target and the insulator is preferably 0.5 mm.
It is the following. In the above structure, the target preferably has a diameter of 150 to 260 mm. In the above structure, the target material is preferably an impurity that reduces the resistance value, for example, 3 such as P, B, Sb, As or Ga.
It is Si (silicon) doped with at least one of valent or pentavalent impurities. In the above configuration,
Preferably, the magnetic field generator is rotated by a rotary drive and is configured to sputter the entire surface of the target.

[0013]

In the DC magnetron sputtering apparatus according to the present invention, a mechanism for preventing the protective film from being deposited is attached to the target and the back plate where the protective film has been deposited in the related art. That is, in the past, when an attempt was made to deposit a protective film on a substrate, the protective film was thinly deposited on the entire surface and peripheral surface of the target 62 and the peripheral portion of the surface of the back plate 61, as shown by the shaded area 80 in FIG. . It has been found that when DC power is supplied from the DC power supply 77 in this state, the thin protective film deposited on the shaded portion 80 causes dielectric breakdown and abnormal discharge occurs. Therefore, in order to prevent the protective film from being deposited on the shaded portion 80, an insulator (for example, SiO ₂ , glass, quartz, Si ₃₎ having a material and a thickness that does not cause dielectric breakdown is used.
N ₄ ) and a magnetic field generator for sputtering the entire surface of the target. Although a protective film is deposited on the surface of the insulator, it is possible to prevent dielectric breakdown of the protective film due to the insulating action of the insulating film. Further, the gap between the insulator and the target is set to a required gap so that a protective film that may cause dielectric breakdown is not deposited. A magnetic field generator sputters the deposited protective film on the entire surface of the target to prevent the protective film from being deposited on the entire surface of the target.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows the configuration of a magnetron sputtering apparatus according to the present invention. In FIG. 1, 1 is a target, and the target 1 is arranged on the back plate 2. The target 1 is formed of Si doped with at least one of trivalent or pentavalent impurities such as P, B, Sb, As, and Ga. The target 1 has a resistance value reduced by the doped impurities and has conductivity. 3 is a cathode, and the cathode 3 has, for example, a cylindrical shape,
As will be described later, the magnetic field generator 14 is incorporated therein. The back plate 2 is attached on top of the cathode 3.

The planar shape of the target 1 is circular, and in the case of the present embodiment, it is φ200 mm, for example. A ring-shaped insulator 4 is arranged around the target 1 and on the upper surface of the back plate 2. The thickness of the insulator 4 is substantially the same as the thickness of the target 1. The insulator 4 covers the peripheral portion of the upper surface of the back plate 2 and the peripheral surface of the target 1. In the present embodiment, for example, glass is used as the material of the insulator 4. The material of the insulator 4 may be one having an electrical insulating action, such as synthetic quartz glass or SiN.
The sintered body may be Si, or the amount of doping may be reduced to increase the specific resistance. The inner diameter of the insulator 4 is the target 1
The gap between the peripheral surface of the insulator and the inner peripheral surface of the insulator 3 is, for example, 0.25.
The size is set to be mm. The size of this gap is
It is preferably set to 0.5 mm or less. With the gap in this range, it is possible to prevent a thin SiN film that causes abnormal discharge from depositing on the peripheral surface of the target 1 and the surface of the back plate 2. The planar shape of the target 1 may be a shape other than a circle. The shape of the insulator 4 is also changed according to the planar shape of the target 1.

Reference numeral 5 is a reaction chamber, the inside of which is brought to a required reduced pressure state. The cathode 3 is fixed to the lower part inside the reaction chamber 5 via an insulator 6. Cooling water is supplied into the cathode 3 in order to cool the target 1 as shown by an arrow A,
Discharge as indicated by arrow B. For the cathode 3, a DC power supply 7
Power is supplied from. The power supplied from the DC power supply 7 is, for example, 3 KW. Further, a cylindrical shield 8 is arranged around the cathode 3 so that the supplied electric power is concentrated on the target 1.

Ar gas and N ₂ gas are introduced into the reaction chamber 5 through the corresponding supply pipes through the valves 9 and 10, respectively. The flow rates of Ar gas and N ₂ gas are controlled to desired flow rates by a flow meter (not shown). The Ar gas and N ₂ gas introduced into the reaction chamber 5 are supplied to the valve 11 and the orifice 1.
Exhausted through 2. The internal pressure of the reaction chamber 5 is 1
The discharge amount is adjusted by the orifice 12 so that the desired pressure can be obtained. Illustration of a drive system and a control system for adjusting the orifice 12 is omitted. As an example of film forming conditions, the flow rate of Ar is 50 SCCM, the flow rate of N ₂ is 40 SCCM,
The pressure is 1 mTorr.

Inside the cathode 3, a magnetic field generator 14 is provided.
Are placed. The magnetic field generator 14 is rotatably installed by a rotation drive device 15. The magnetic field generated by the magnetic field generator 14 is generated so as to sputter the entire surface of the target 1 based on the configuration of the magnetic circuit arranged inside and the rotating action of the magnetic circuit. As the magnetic field generator 14, for example, it is desirable to use the magnetic field generator proposed in Japanese Patent Laid-Open No. 3-249176. The magnetic field generator 14 includes magnets arranged in a predetermined arrangement inside, and the magnets enable sputtering of the entire surface of the target. As the magnetic field generator 14, any device can be used as long as it has a magnetic circuit such as a magnet that can sputter the entire surface of the target 1.

A substrate 16 is arranged above the target 1. Illustration of the structure for supporting the substrate 16 is omitted. The distance between the substrate 16 and the target 1 is, for example, 1
It is set to 45 mm.

As described above, in the atmosphere of Ar gas and N ₂ gas, the target 1 is produced based on the above-mentioned respective film forming conditions.
By DC magnetron sputtering, a SiN film is formed on the surface of the substrate 16 placed above the target 1. At this time, since the insulator 4 is provided, it is possible to prevent the SiN film from being deposited on the target peripheral surface and the peripheral edge of the back plate surface. Although a thin SiN film is deposited on the surface of the insulator 4, this insulating film does not cause dielectric breakdown due to the insulating function of the insulator 4. Since the magnetic field generator 14 is provided, it is possible to prevent the entire surface of the target 1 from being sputtered and depositing the SiN film on the entire surface of the target. Therefore, it is possible to eliminate the deposition of the SiN film that causes abnormal discharge on the entire surface of the target 1, and prevent the occurrence of abnormal discharge. In FIG. 1, 17 is a plasma discharge region generated between the target 1 and the substrate 16.

FIG. 2 shows the above-mentioned film forming conditions and a flow rate of Ar of 50.
SCCM, N ₂ flow rate 40 SCCM, pressure was 1 mTorr, distance between target 1 and substrate 16 was 145 mm, and power supply was 3 KW. When SiN film was formed on substrate 16, abnormal discharge frequency (times / min) for 60 minutes was measured. It is a thing. As is clear from FIG. 2, no abnormal discharge occurred. As described above, according to the configuration of the DC magnetron sputtering apparatus according to the present embodiment, since there is no possibility of depositing the SiN film on the entire surface and the peripheral surface of the target 1 and the surface of the back plate 2, the abnormal discharge is prevented. It was possible to eliminate the occurrence.

By the way, when the SiN film was formed under the above film forming conditions with only the pressure of 4 mTorr, the SiN film was deposited around the target 1 and abnormal discharge occurred. From this, it was found that there is an optimum film forming condition corresponding to the diameter of the target 1. Then, as a result of investigating the optimum conditions using the pressure and the supplied power as parameters, the data shown in FIG. 3 were obtained. In FIG. 3, the area C is φ200 mm
Is an optimal region in which abnormal discharge does not occur, and region D is an optimal region in which abnormal discharge does not occur for a target of φ184 mm. The diameter of the target used in the DC magnetron sputtering apparatus of the present invention is
It is desirable to be included in the range of 150 to 260 mm.

FIG. 4 shows a graph comparing the film forming rate by the DC magnetron sputtering method according to the present invention with the film forming rate by the conventional RF magnetron sputtering method, and the horizontal axis represents the N ₂ flow rate. According to the DC magnetron sputtering method according to the present invention, it is possible to achieve a film forming rate almost twice as high as that of the conventional RF magnetron sputtering method.

As another embodiment, film forming conditions, Ar flow rate 100 SCCM, O ₂ flow rate 20 SCCM, pressure 1 mTorr, distance between target 1 and substrate 16 144 mm, power supply 3
An example in which the protective film TaO is formed on the substrate 16 under KW can be given. In this example, a TaO film having a film forming rate of 300 Å / min and a refractive index (N _f ) of about 2.1 could be produced without causing abnormal discharge. With respect to the other protective films, the protective film can be similarly formed at a high film forming rate.

[0025]

As is apparent from the above description, according to the present invention, since the target and the back plate are provided with the structure for preventing the protective film which causes the abnormal discharge from being deposited, the abnormal discharge is prevented. This makes it possible to prevent the generation of dust and improve the quality of the protective film in a magneto-optical disk or the like. In addition, unlike the conventional DC magnetron sputtering method, it is possible to form a protective film under predetermined optimum film forming conditions without limiting the supply of DC power, which allows the conventional RF magnetron sputtering to be performed. In comparison, the protective film can be formed at high speed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a DC magnetron sputtering apparatus according to the present invention.

FIG. 2 is a graph showing the number of occurrences of abnormal discharge when a film is formed by the device according to the present invention.

FIG. 3 is a graph showing a range of optimum film forming conditions corresponding to a target size.

FIG. 4 is a graph comparing the film forming rate of the method according to the present invention with the film forming rate of the conventional method.

FIG. 5 is a partial vertical sectional view for explaining a film structure of a magneto-optical disk.

FIG. 6 is a configuration diagram showing a conventional RF magnetron sputtering apparatus.

FIG. 7 is a configuration diagram showing a conventional DC magnetron sputtering apparatus.

FIG. 8 is a graph showing the number of occurrences of abnormal discharge in the conventional device.

FIG. 9 is a configuration diagram for explaining deposition of a protective film that causes abnormal discharge.

[Explanation of symbols]

 1 ... Target 2 ... Back plate 3 ... Cathode 4 ... Insulator 5 ... Reaction chamber 7 ... DC power source 8 ... Shield 14 ... Magnetic field generator 15 ... Rotation drive device 16 ... Substrate 17 ... Plasma discharge region

Claims (5)

[Claims] 1. A target attached to a back plate, and a magnetic field generating means for generating a magnetic field on the surface of the target,
In a DC magnetron sputtering apparatus having a cathode to which the back plate is attached and a DC power source for supplying DC power to the cathode, an insulator is provided to cover the peripheral surface of the target and the peripheral portion of the surface of the back plate, and the magnetic field is generated. A DC magnetron sputtering apparatus, wherein the means includes a magnet for sputtering the entire surface of the target. 2. The DC magnetron sputtering apparatus according to claim 1, wherein the distance between the target and the insulator is 0.5 mm or less. 3. The DC magnetron sputtering apparatus according to claim 1, wherein the target has a diameter of 150 to 26.
A DC magnetron sputtering device characterized by being 0 mm. 4. The DC magnetron sputtering apparatus according to claim 1, wherein the material of the target is silicon containing impurities that reduce a resistance value.
C magnetron sputtering equipment. 5. The DC magnetron sputtering apparatus according to claim 1, further comprising a rotation driving device that rotates the magnetic field generating means.