JP3807686B2 - Opposite target type sputtering system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, a pair of targets are arranged facing each other at a predetermined interval in a vacuum chamber, sputter plasma is generated in a space between them, and the substrate disposed on the side so as to face this space. The present invention relates to a counter target type sputtering apparatus in which a film is formed.
[0002]
[Prior art]
The above-mentioned facing target type sputtering apparatus is already known in Japanese Patent Publications Nos. 63-20303, 63-20304, 62-14633, etc. filed by the present inventors, and has the basic configuration shown in FIG. It has a configuration. That is, the targets 110a and 110b disposed so as to face each other with a space 120 of a predetermined distance in the vacuum chamber 10, and a target that generates a magnetic field so that the magnetic flux uniformly covers the side surface of the outer edge portion of the facing space 120. A sputtering unit comprising magnetic field generating means 130a and 130b provided on the back of each of 110a and 110b is provided, and the substrate 20 is arranged so as to face the facing space 120 by the substrate holder 21 provided on the side thereof. It has become. 140a and 140b in the figure are shields for protecting the portions other than the front surfaces of the targets 110a and 110b of the target portions 100a and 100b from being sputtered.
[0003]
Therefore, after exhausting the inside of the vacuum chamber 10 through the exhaust port 30 by an exhaust system (not shown), a sputtering gas such as argon is introduced from the introduction port 40 by a gas introduction means (not shown), and a sputtering power source comprising a DC power source as shown in the figure. When the sputtering power is supplied by 50 with the shields 140a and 140b and thus the vacuum chamber 10 as the anode (anode) (ground) and the targets 110a and 110b as the cathode (cathode), sputtering plasma is applied to the facing space 120 between the targets 110a and 110b. Then, sputtering is performed, and a thin film having a composition corresponding to the composition of the targets 110a and 110b is formed on the substrate 20.
[0004]
At this time, since the magnetic field is formed in the direction perpendicular to the surfaces of the targets 110a and 110b by the above-described configuration, high-energy electrons are confined in the facing space 120 between the targets 110a and 110b, and sputter plasma is generated. The ionization of the sputtering gas here is promoted to increase the sputtering speed, and a high-speed film can be formed. In addition, the substrate 20 is arranged on the side of the targets 110a and 110b without facing the targets 110a and 110b, like a conventional bipolar sputtering apparatus in which a substrate and a target are arranged to face each other. Therefore, the collision of ions and electrons with the substrate 20 is extremely reduced, the thermal radiation from the targets 110a and 110b is small, and the rise in the substrate temperature is also small. Therefore, a low temperature film can be formed. In this way, various materials including magnetic materials, which were difficult to form at high speed by the conventional magnetron sputtering method, can be formed at low temperature and high speed, making it possible to manufacture magnetic thin films, thin film magnetic recording media, etc. It's being used.
[0005]
However, this method usually uses a rectangular or circular target. Regardless of the shape of the target, the target surface that is sputtered and eroded tends to concentrate at the center, improving the efficiency of use of the target. I found it necessary (IEEE Trans on Magnetics MAG-17, pp.3175-3177 (1981)). In addition, when a rectangular target is used, the target erosion pattern becomes asymmetric with respect to the center of the target, a film thickness distribution occurs in the width direction of the substrate, and improvements in productivity and thin film uniformity are required. I understood that.
[0006]
On the other hand, the present inventors disclosed in Japanese Patent Publication No. 3-2231 and Japanese Patent Publication No. 63-54789 as an improved technique for expanding the target erosion characteristics over the entire target surface, a magnetic field generating means around the outside of each target. And a core is arranged at the end of the magnetic pole, which is the magnetic field generating part, and a magnetic field is generated around the target.
[0007]
With this configuration, since the magnetic field is formed between the cores arranged directly opposite each other without passing through the target, the magnetic field distribution is less affected by the magnetic permeability, saturation magnetization, and target thickness of the target material, and is constrained by sputtering plasma. A magnetic field for use was formed around the outer periphery of the target, and its erosion area expanded from the center of the target to the periphery of the outer edge, greatly improving the target utilization efficiency. However, it has been found that the discharge voltage becomes high during sputtering, and stable sputtering cannot be performed unless the sputtering gas pressure is high.
[0008]
Furthermore, as a solution to this problem, the present inventors have developed a technique for even more uniformly expressing the plasma constraint conditions, which is a feature of the opposed target sputtering method, over the entire target surface. Proposed in publications such as 5-75827. In addition to the magnetic field lines (magnetic field) perpendicular to the target surface in the conventional facing target type sputtering, these technologies are arc-shaped magnetic field lines that close to the target surface in the vicinity of the entire periphery of the outer edge of the target surface. And an electron reflecting means for reflecting electrons in the vicinity of the end of the magnetic pole. In this technology, high-energy electrons flying in the space between the opposing targets drift in the space, and drift without being absorbed by the magnetic pole over the entire circumference of the target outer edge due to the electromagnetic field near the surface of the target outer edge. As a result, the ionization efficiency of the sputter gas is remarkably increased as a whole, and a technique free from the above-mentioned problems has been realized.
[0009]
As a result, it has become possible to increase the sputtering efficiency over the entire target. Results of forming alloy thin films such as Co-Cr and Co-Cr-Ta, which are expected as ultra-high-density recording materials, on polyethylene terephthalate (PET) films and polyethylene naphthalate (PEN) films using the sputtering equipment of this technology It was confirmed that a magnetic thin film with excellent magnetic properties and microstructure can be produced on a low-temperature substrate at 150 ° C (J. Mag. Soc. Jpn., 18, Suppl. S1, pp.19-2, pp.331- 334, others). With this sputtering technology, it is possible to form a thin film with excellent characteristics such as fine structure that cannot be realized by the conventional sputtering method in which the substrate and the sputtering source face each other, and uniform erosion is possible across the entire target, and a rectangular target was used. In some cases, the symmetry of the target erosion pattern with respect to the center of the target was also dramatically improved.
[0010]
However, even in this improved facing target type sputtering apparatus, the recoil gas particles and sputtered particles sputtered from the target surface are not scattered in the vacuum chamber from all the sides of the space between the targets. For this reason, even if sputtering can be performed uniformly from the entire surface of the target and a thin film having a uniform film thickness distribution can be realized with good control, only a part of the target side space facing the substrate can be formed. In other words, there is a problem that the quality of the thin film formed on the substrate deteriorates as a result of the gas built in the vacuum chamber wall being released during sputtering due to the particles scattered on the vacuum chamber wall.
[0011]
On the other hand, the inventors of the present invention previously described an opposed space type opposed target sputtering apparatus in which the opposed space having the following configuration is partitioned by a target except the substrate side in Japanese Patent Application No. 8-162676. Proposed. That is, the space is defined by a pair of first targets arranged opposite to each other with a predetermined distance space and a second target arranged so as to cover a side surface excluding the opening facing the substrate in the space. A magnetic field generating means for generating a magnetic field for constraining the sputtering plasma is arranged along the outer periphery of each of the first targets so that the magnetic poles oppose each other in the vicinity of the outer side, and the magnetic field is generated. A cylindrical magnetic field surrounding the pair of first targets by the generating means, a magnetic field closed in an arc from the magnetic pole to the inner surface near the surface of the outer edge of the first target, and near the surface of the second target A magnetic field parallel to the surface and a magnetic field closed in an arc from the magnetic pole to the inner surface in the vicinity of the surface of both side edges adjacent to the magnetic field generating means of the second target; Electron reflecting means for reflecting electrons is provided at the end of the magnetic pole facing the partition space and the opening end of the partition space of the second target, and sputter plasma is generated in the partition space, in front of the opening. This is a counter target type sputtering apparatus in which a thin film is formed on a placed substrate.
[0012]
In this apparatus, as described above, the electron reflecting means is provided in the partitioned space in which the entire surface except for the opening facing the substrate in the space between the pair of opposed first targets is surrounded by the second target. Through the interaction of electrons constrained by each magnetic field, high-density plasma is generated and restrained on almost the entire surface of each target, realizing almost uniform sputtering on the entire surface of all targets, and solving the above-mentioned problems It was done.
[0013]
[Problems to be solved by the invention]
By the way, in the above-mentioned facing target type sputtering apparatus, when the sputtering power input in order to increase the film forming speed was increased, the tendency of the film quality of the deposited film to decrease was recognized. This tendency was particularly remarkable in an apparatus provided with electron reflecting means. This problem is a very big problem in industrial production where production speed is a large cost factor.
The present invention has been made in view of such problems, and an object of the present invention is to provide an opposed target sputtering apparatus suitable for industrial production that does not deteriorate the film quality even when the input power is increased.
[0014]
[Means for Solving the Problems]
The above object is achieved by the present invention described below. That is, according to the present invention, a pair of targets are arranged opposite to each other at a predetermined interval in a vacuum chamber, and a magnetic field generating means made of a permanent magnet is provided outside the target along the outer periphery of the target. A counter target type sputtering apparatus in which a plasma trapping magnetic field is formed so as to surround the substrate, a sputtering plasma is generated in the opposing space, and a thin film is formed on a substrate disposed on a side of the opposing space. Providing a potential storage part that reflects electrons that can be taken in and out from the outside of the tank , projecting from the vacuum tank wall surface to the inside of the tank along the outer periphery so as to surround the target and its support part, and the storage part from the outside of the tank A counter-target type sputtering apparatus characterized in that a permanent magnet of a magnetic field generating means is accommodated in a hole that is drilled and cut off from a tank .
[0015]
The present invention has been made as follows. That is, when the cause of the problem is variously examined, this problem is mainly caused by the impurity gas generated when the permanent magnet of the magnetic field generating means becomes high temperature. In some cases, this problem is further caused by a decrease in magnetic force due to the high temperature of the permanent magnet. It has been found out that the increase of electrons flying to the substrate accompanying the decrease of the plasma trapping magnetic field is also added.
According to the present invention, since the permanent magnet of the magnetic field generating means is provided substantially in the atmosphere outside the vacuum chamber with the above configuration, the above-described problem of impure gas is completely solved. Furthermore, due to the structure outside the vacuum chamber, the natural cooling is larger in the atmosphere than in the vacuum in the chamber, and there is no space restriction, so that the cooling means for forced cooling can be freely designed as necessary. It also solved the problem of reduced magnetic force.
[0016]
From the gist of the present invention, it is obvious that the present invention can be widely applied to the opposed target sputtering apparatus in which the permanent magnets of the magnetic field generating means are provided on the outside along the outer periphery of the opposed target. In particular, in the case where the magnetic pole of the magnetic field generating means protrudes to the opposite space side from the front surface of the target so that the entire surface of the target is sputtered uniformly, the problem that the protruding part of the magnetic field generating means touches the sputter plasma and is heated is remarkable. The effect is great. Further, in the case where the electron reflecting means is provided at the tip of the magnetic field generating means, the electron reflecting means may be sputtered in some cases, and the above problem is a big problem from the viewpoint of stable production, and the present invention is lacking in industrial production. It will not be possible.
Hereinafter, the present invention will be described in detail based on examples.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
In this embodiment, in the conventional counter target type sputtering apparatus of FIG. 1 described above, the target portions 100a and 100b have the same basic structure as that disclosed in the above Japanese Patent Publication No. 5-75827. FIG. 2 is a side sectional view of the target portion 100a of the embodiment, and FIG. 3 is a sectional view taken along the line AB of FIG. Therefore, the configuration excluding the target portions 100a and 100b is the same as that of the conventional example of FIG. 1 described above, and the description thereof is omitted. 1 to 3, the same symbols are used for the same symbols.
As shown in FIG. 2, the target portions 100 a and 100 b of this example are detachably attached to the tank wall 11 of the vacuum chamber 10. FIG. 2 shows the target unit 100a, but the target unit 100b has the same configuration as the target unit 100a except that the magnetic poles of the permanent magnets of the magnetic field generating means 130a and 130b are reversed.
[0018]
The target 110a is attached to the front surface of the cooling table 150a so as to be replaceable by bolts 111a at regular intervals at the periphery thereof. As shown in FIG. 3, a cooling groove 151a is provided in a zigzag manner on the front surface of the cooling table 150a by a partition wall 152a, and a cooling jacket is formed when the target 110a is attached. A cooling medium supply port 153a and an outlet 154a are provided at both ends of the cooling groove 151a so that the target 110a can be directly cooled by circulating cooling water. Therefore, it is possible to perform cooling with very good cooling efficiency and to cope with high-speed film formation. The cooling table 150a is attached to the support plate 160a with bolts 156a at regular intervals via a packing 155a made of an electrical insulating material.
[0019]
On the support plate 160a, a storage portion 131a for storing the magnetic field generating means 130a has a predetermined gap G along the periphery of the target 110a and surrounds the outer side of the target 110a from the front surface of the target 110a so as to surround the outer periphery. Projected by a predetermined length d. As shown in the figure, the storage part 131a has a structure in which holes of a predetermined depth opened to the outside of the tank for inserting and removing the permanent magnet of the magnetic field generating means 130a from the outside of the tank are formed in the block body at a predetermined pitch, and the magnetic field generating means 130a has a configuration in which rod-shaped permanent magnets are inserted into the holes of the storage portion 131a in the illustrated magnetic pole arrangement and fixed with stoppers 132a, and a large number of permanent magnets are arranged in parallel around the target 110a at a constant pitch. It has become. The storage part 131a is made of a conductive material and is configured to function also as a part of an electron reflecting means described later. In this example, the storage portion 131a and the support plate 160a are made of a structural material such as a metal having good thermal conductivity, specifically, an aluminum block and an NC lathe, and the cross section shown in FIG. The base portion is used as a support body 160a of the support portion, and holes are formed in the vertical portion from the bottom side at a predetermined pitch to form a storage portion, which has a seamless integrated structure. As a result, it was possible to obtain a storage portion 131a that was completely cut off from the inside of the tank, had no vacuum leakage, and was able to sufficiently cool the permanent magnet stored by heat radiation from the support plate 160a only by natural cooling.
[0020]
An electron reflecting plate 170a serving as an electron reflecting means that is held at a negative potential capable of reflecting the electrons reaching here is attached to the front end portion of the housing portion 131a, as shown in the drawing, a bolt 111a for mounting the mounting portion around the target 110a. It is provided so as to cover it. In this example, the electron reflecting plate 170a is configured to use a magnetic material having a high magnetic permeability, specifically, permalloy, and also serves as a core of the magnetic field generating means 130a.
As described above, the target unit 100a has a unit configuration in which the entire support plate 160a is provided. The target unit 100a is installed in the vacuum chamber 10 by attaching the support plate 160a to the tank wall 11 of the vacuum chamber 10 with the bolts 162a at regular intervals via the packing 161a made of an electrical insulating material, as shown in the figure. The Therefore, at the time of cleaning or the like, the target portion 100a can be removed, which can be carried out very efficiently, and a great effect can be obtained in terms of maintainability and overall productivity improvement.
[0021]
The magnetic field generating means 130a and 130b are provided outside the targets 110a and 110b, and the target portions 100a and 100b provided with the electron reflectors 170a and 170b are extended from the magnetic pole ends to the mounting portions around the targets 110a and 110b. The basic configuration is the same as the target part of the opposed target type sputtering apparatus disclosed in the above Japanese Patent Publication No. 5-75827, and, as disclosed in the publication, a high-quality thin film is formed by the same action as described below. In addition, the target 110a and 110b can be sputtered uniformly over the entire surface, and a film with high target use efficiency can be formed.
That is, with this configuration, the following magnetic field lines for trapping plasma are formed in the targets 110a and 110b and the facing space 120. The first is a vertical magnetic field line formed in a cylindrical shape in the vertical direction of the targets 110a and 110b so as to surround the targets 110a and 110b and the facing space 120 between the magnetic poles by the magnetic field generating means 130a and 130b. The second is an auxiliary magnetic field line formed in an arc shape on the outer edge of each of the targets 110a and 110b from the tip of the electron reflectors 170a and 170b that also serves as the core of the magnetic field generating means 130a and 130b to the front of the targets 110a and 110b. is there.
[0022]
The γ electrons radiated from the central part of the surface of the targets 110a and 110b by the perpendicular magnetic field lines and accelerated by the cathode potential drop part are constrained by the vertical magnetic field lines in a string shape, and reciprocate between the targets 110a and 110b. . On the other hand, the γ electrons generated at the outer edges of the targets 110a and 110b reach the negative potential electron reflectors 170a and 170b that are restrained by the auxiliary magnetic field lines and can reflect the electrons. Returned while being constrained by the auxiliary magnetic field lines, a part is returned to the center of the facing space 120.
[0023]
Accordingly, γ electrons are accumulated in the facing space 120 to generate high-density plasma, low-voltage, low-gas pressure sputtering is realized, and a high-quality thin film with little internal distortion, sputtering gas, or the like can be formed. Further, a plasma trapping magnetic field similar to that of the well-known flat-plate magnetron sputtering is formed on the outer edge portions of the targets 110a and 110b by the auxiliary magnetic field lines, and γ electrons reflected by the electron reflectors 170a and 170b are effectively targeted. 110a and 110b are trapped in the vicinity of the outer edge surface and the plasma density of the outer edge can be increased, so that substantially uniform sputtering is realized up to the outer edge, and the target 110a and 110b are used almost uniformly over the entire surface. High film formation can be achieved.
[0024]
By the way, in the above configuration, the tip portions of the magnetic field generating means 130a and 130b protrude from the front surfaces of the targets 110a and 110b, and the electron reflecting plates 170a and 170b are provided, so that the magnetic field generating means 130a and 130b, particularly The tip is heated by radiant heat from the targets 110a and 110b, collision of electrons and the like with the electron reflectors 170a and 170b, etc., but in this embodiment, the storage portion 131a with good thermal conductivity directly connected to the outside of the tank in the atmosphere. Since it is housed in 131b, it can be maintained at a temperature that does not impede practical use. If natural cooling is not sufficient, a cooling pipe may be provided on the support plates 160a and 160b, and the housings 131a and 131b may be configured as a jacket to perform forced cooling.
In the present embodiment, the housing part and the support plate that are integrally formed with no concern about gas leakage are shown. However, it is apparent from the gist of the present invention that a structure in which each part is connected by welding or the like can also be applied. Moreover, although the cooling property is good, a storage portion in which a hole suitable for storing a rod-shaped magnet is formed in the block is shown, the structure of the storage portion is not limited, and it is suitable for the shape of a permanent magnet used for a continuous groove, Or it can apply according to the objectives, such as a structure with easy cooling.
[0025]
Furthermore, although the whole target unit with good maintenance workability can be removed from the vacuum chamber, a configuration in which the storage unit is directly projected on the vacuum chamber wall and the target cooling stand is also installed on the vacuum chamber wall may be employed. The present invention can be applied to any configuration in which the permanent magnet of the magnetic field generating means can be disposed from outside the vacuum chamber so that the magnetic poles are opposed to each other around the target facing from the outside of the vacuum chamber and separated from the inside of the vacuum chamber.
[0026]
As described above, this storage unit configuration is further applied with radiant heat from the side surface target, the front end of the storage unit is located in the partition space, and the substrate of the opposing space 120 with severe thermal conditions for the permanent magnet of the magnetic field generating means. The above-mentioned Japanese Patent Application No. 8-162676, in which a target is also provided on the side surface except for the side surface facing 20, and sputter plasma is formed in a partitioned space partitioned by the target except for the opening on the side surface facing the substrate 20. It is particularly preferably applied to the sputtering apparatus proposed in the specification.
[0027]
【The invention's effect】
As described above, the permanent magnet of the magnetic field generating means is cut off from the inside of the vacuum chamber, and the storage portion that is stored from the outside of the chamber is projected from the inside of the vacuum chamber wall and arranged around the target. This eliminates the influence on the film formation of the gas released from the permanent magnet, and further prevents the permanent magnet from being thermally deteriorated, and has a great effect on improving the performance of the opposed target type sputtering apparatus, particularly on the long-term stability. It is what you play.
As described above, the present invention greatly contributes to the realization of an industrial scale facing target type sputtering apparatus that requires high-speed film formation.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a basic configuration of a conventional opposed target sputtering apparatus.
FIG. 2 is a schematic sectional side view of a target portion according to an embodiment of the present invention.
FIG. 3 is a schematic cross-sectional view taken along the line AB in FIG. 2;
[Explanation of symbols]
10 vacuum chamber 20 the substrate 30 outlet 40 inlet 50 sputtering power source 100a, 100b target unit 110a, 1 1 0b target 120 facing the space 130a, 130b field generating means 140a, 140b shield 150a, 150b cooling stage 160a, 160b support plate 170a, 170b Electron reflector

Claims (8)

A pair of targets are arranged opposite to each other at a predetermined interval in the vacuum chamber, and a magnetic field generating means made of a permanent magnet is provided along the outer periphery of the target so as to surround the facing space between the targets. In a counter target type sputtering apparatus in which a magnetic field is generated, sputter plasma is generated in the counter space, and a thin film is formed on a substrate disposed on the side of the counter space. Protruding from the vacuum chamber wall to the inside of the tank along the outer periphery so as to surround, a storage portion of the potential that reflects the electrons that can be taken in and out from the outside of the bath is provided, and the storage portion is drilled from the outside of the bath. A facing target type sputtering apparatus, wherein a permanent magnet of a magnetic field generating means is accommodated in a blocked hole. The tip portion of the hole drilled in the housing portion is protruded to the opposite space side than the target surface, the permanent magnet whose magnetic poles are accommodated so as to be positioned in the protruding position, circle periphery front vicinity of the target The opposed target sputtering apparatus according to claim 1, wherein an arc-shaped magnetic field is formed.   The opposed target sputtering apparatus according to claim 2, further comprising an electron reflecting means for reflecting electrons in the sputter plasma inside the tank at the tip of the storage section.   The opposed target sputtering apparatus according to any one of claims 1 to 3, wherein the storage portion is an integrally formed body without a joint.   The opposed target sputtering apparatus according to claim 4, wherein the storage portion and the support portion that supports the storage portion and attaches to the vacuum chamber are integrally formed bodies.   The integral molded body is a molded body having an inverted T-shaped cross section cut out from an aluminum block, and the bottom side thereof is used as a support portion, and holes for storing permanent magnets are formed in the vertical portion from the bottom side at a constant pitch. The counter target type sputtering apparatus according to claim 5, wherein the opposing target type sputtering apparatus is used.   The counter target sputtering apparatus according to any one of claims 1 to 6, wherein the target unit is attached to the support unit so as to be removable from the vacuum chamber through the support unit.   The counter-target type sputtering apparatus according to claim 1, further comprising a side target surrounding a side surface excluding a side surface facing the substrate in the counter space.

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