TWI425108B - Magnetron sputtering device and sputtering method - Google Patents

Description

Magnetron sputtering device and sputtering method

The present invention relates to a magnetron sputtering apparatus and a sputtering method.

A method of forming a thin film on a substrate for a solar cell or a semiconductor wafer or the like is a sputtering method. In particular, a magnetron sputtering device in which a magnet is disposed on the back side of a cathode to which a target is mounted is excellent in stability of film formation, and the size of the target is also easy, and is widely used. Use. In order to improve productivity, it is attempted to uniformize the depth of erosion of the target as much as possible and increase the number of substrates that can be produced by one target. Further, in order to improve the uniformity of the film thickness distribution on the substrate, it has been studied to control the shape of the etching depth to a desired shape.

In this way, the control of the erosion depth shape of the target and the control of the plasma density distribution of the discharge space on the surface side of the target are slightly equivalent. The plasma density distribution is mainly determined by the electric field and the magnetic field of the discharge space. In particular, the magnet disposed on the back side of the target is the shape of the magnetic field made in the discharge space on the surface side of the target. Have a big impact. Therefore, in order to control the shape of the erosion depth, multiple systems are designed for the shape of the magnet, or the magnet is rotated or reciprocated.

In magnetron sputtering, as a general magnet structure, it has a structure as shown in Figs. 8A to 8C. 8A is a front view of a magnet structure, FIG. 8B is a cross-sectional view taken along line A-A of the magnet structure of FIG. 8A, and FIG. 8C is a cross-sectional view taken along line B-B of FIG. 8A. As shown in FIG. 8A, for example, a permanent magnet (hereinafter referred to as an inner magnet) 11 is disposed at a certain area on the yoke 14 in a direction in which the S pole becomes a surface. Then, a permanent magnet (hereinafter referred to as an outer magnet) 12 is disposed so as to surround the inner magnet 11 and the N pole having the opposite polarity is in the direction of the surface. The inner magnet 11 and the outer magnet 12 are disposed on the yoke 14 of a normal ferromagnetic body. Hereinafter, the inner magnet 11, the outer magnet 12, and the yoke 14 are collectively referred to as a magnet unit 10.

The inner magnet 11 and the outer magnet 12 are mostly fixed to the yoke 14 by an adhesive. Therefore, in order to facilitate the work, the yoke 14 uses a flat plate. Since the inner magnet 11 and the outer magnet 12 generate a force in the direction of adsorption, in order to fix these firmly, a certain degree of strength is required at the yoke.

Further, the yoke 14 is also provided with an effect of increasing the strength of the magnetic field as compared with the case where the yoke is not present. Therefore, in general, the yoke 14 is used to have a certain thickness as a high magnetic permeability so as not to be magnetically saturated. In the case of a large-sized sputtering apparatus, a rectangular target having a rectangular surface to be sputtered is used. In this case, as the magnet unit, a rectangular shape as shown in Fig. 8A is used. Magnetron sputtering is performed by arranging one or a plurality of such magnet units 10 for one rectangular target. As a large-sized sputtering apparatus using such a magnet unit 10, for example, it is disclosed in Japanese Laid-Open Patent Publication No. 2001-140069.

However, in the magnet unit 10 of the prior art, there are the following problems. In other words, as a method of easily changing the magnetic field shape or the magnetic field strength on the surface side of the target, there is a thin plate on which the ferromagnetic body is attached to the target surface of the magnet 11 and the outer magnet 12 on the inner side of the magnet unit 10 ( Hereinafter, a method called a magnetic plate). The magnetic body plate is magnetically short-circuited by the N pole and the S pole of the inner magnet 11 and the outer magnet 12, and the magnetic field strength generated from the N pole and the S pole of the region where the magnetic body plate is attached can be obtained. reduce. The magnetic plate is so thin that it becomes magnetically saturated, and a magnetic field is formed to pass through the magnetic plate to form a certain magnetic field on the surface side of the target. Therefore, the magnetic field strength of the entire magnet unit 10 can be controlled by changing the position and thickness of the attached magnetic body plate.

However, the magnet unit 10 is usually arranged in close proximity to the structure on the target side. Specifically, between the target and the magnet unit 10, a cavity wall or the like may be present. In order to increase the magnetic field strength on the surface side of the target as much as possible, it is necessary to reduce the distance between the magnet unit 10 and the target, and the magnet unit 10 is arranged with a gap of about several mm with respect to the cavity wall or the like. .

Therefore, in order to attach the magnetic body plate to the surface of the magnet unit 10, it is necessary to move the magnet unit 10 toward the opposite side of the target material largely, and to make a space on the surface side of the magnet unit 10. In the recent large-scale sputtering apparatus, for example, a substrate having a size of more than 1 m, since the magnet unit 10 is also large and heavy, the mechanism for moving the magnet unit 10 from the target side to a large extent is also It will become a large and complicated one, and there is a problem that the manufacturing cost of the device becomes high.

According to the present invention, it is possible to change the thickness of the yoke from the back side of the magnet unit without largely moving the magnet unit from the target side, and to change the magnetic field shape or the magnetic field strength on the surface side of the target. And a technology that can reduce the manufacturing cost of the device.

A magnetron sputtering apparatus according to one aspect of the present invention is characterized by comprising: a cathode having a mounting surface of a target as a surface side; and a magnet unit disposed on a back side of the cathode, and (a) The magnet unit includes an inner magnet formed of a permanent magnet having a magnetic pole surface of one polarity toward the cathode side, and a rectangular shape so as to surround the inner magnet, and opposite to the inner magnet An outer magnet formed by a permanent magnet facing the cathode side; a non-magnetic body fixing the inner magnet and the outer magnet; and the inner magnet facing the cathode and the outer magnet pole surface On the opposite side, a yoke made of a ferromagnetic material in which the inner magnet and the magnetic pole of the outer magnet are connected, and (b) the yoke has a plate shape and is arranged in a rectangular shape by the foregoing. The outer side of the outer magnet is divided into a plurality of faces orthogonal to each other, and the yokes that are divided are exchangeable. c) The magnet unit is movable in a direction parallel to the back surface of the cathode.

Further, the sputtering method according to another aspect of the present invention is a sputtering method using a magnetron sputtering apparatus, and is characterized in that the film formation is performed by using the above-described magnetron sputtering device. Membrane engineering; and an evaluation project for evaluating the film thickness formed by the film forming process; and changing the thickness of the yoke of the magnetron sputtering device according to the evaluation result of the evaluation project .

According to the present invention, the thickness of the yoke can be changed from the back side of the magnet unit without largely moving the magnet unit from the target side, and the magnetic field shape or magnetic field on the surface side of the target can be easily changed. Strength and can reduce the manufacturing cost of the device.

Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the appended claims.

(First embodiment)

Hereinafter, the magnetron sputtering apparatus according to the first embodiment of the present invention will be described with reference to the drawings. In Fig. 1, a schematic configuration of a magnetron sputtering apparatus of the present embodiment is shown. On the substrate holder 5 in the chamber 1, the substrate 2 is placed. The chamber 1 is evacuated to a vacuum by an exhaust pump (not shown), and a process gas (for example, Ar gas) is supplied to a specific pressure by a gas pipe (not shown).

The target 3 is disposed above the substrate 2 and above. The cathode 4 is provided with a target 3 mounted on a mounting surface, and a cathode 4 is provided in the chamber 1 via an insulator 6.

In the present embodiment, an example in which the back side of the cathode 4 on which the target 3 can be mounted is exposed to the atmosphere is shown. The cathode 4 is connected to a DC power source (not shown). On the back side of the cathode 4, a magnet unit 10 is provided with a gap of several mm. The magnet unit 10 is capable of reciprocating in a direction parallel to the cathode 4 without changing the interval between the cathode and the cathode 4 during film formation via a moving mechanism (not shown).

Next, a magnet unit 10 of the magnetron sputtering apparatus of the present embodiment will be described with reference to Figs. 2A to 2D. Fig. 2A is a front view of the magnet unit 10, and is shown for the appearance of the observation from the side of the target 3. The inner magnet 11 of the elongated rectangular permanent magnet magnetized so as to become the S pole at the front side surface when viewed from the target 3 side is disposed. The magnets 12 on the outer side of the permanent magnet magnetized so as to become the N pole at the front side surface when viewed from the side of the target 3 are disposed so as to surround the inner magnet 11 .

As shown in FIG. 2B which is a cross-sectional view of FIG. 2A or FIG. 2C which is a BB cross-sectional view of FIG. 2A, the inner magnet 11 and the outer magnet 12 are between the non-magnetic bodies. 13 is fixed as a connection. The non-magnetic body 13 is made of, for example, stainless steel or non-magnetic stainless steel, and the inner magnet 11 and the outer magnet 12 are fixed by an adhesive. In Fig. 2D, a section in which the yoke 14 is not present is shown, but the inner magnet 11 and the outer magnet 12 are fixed only by the non-magnetic body 13, and the fixing by the yoke 14 is not required.

The yoke 14 is made of a ferromagnetic material, for example, iron or SUS430. As shown in FIG. 2C, the yoke 14 is connected such that the magnetic pole surface of the inner magnet 11 and the magnetic pole surface of the outer magnet 12 on the opposite side with respect to the target 3 are short-circuited by the magnetic circuit. The yoke 14 here is adsorbed only by the adsorption force (magnetic force) of the magnet (the inner magnet 11 and the outer magnet 12), and the magnet and the yoke 14 are not fixed by a method such as the following.

As shown in FIG. 2B, the yoke 14 is generally provided in a plate shape and is orthogonal to the longitudinal direction of the magnet (the long side direction of the magnet unit 10) of the side magnets arranged in a rectangular shape. It is divided into a plurality of yokes, and the yokes that are divided into sections can be exchanged.

Each of the yokes divided into a plurality of yokes can be exchanged with a yoke having a different thickness. In this case, the longitudinal direction of the outer magnet (the longitudinal direction of the magnet unit 10) is divided into eight, and the six yokes at the center are the same thickness, and the two end portions (front end portions) are two. The yoke is a thinner yoke than the thickness of the six yokes at the center. In the present embodiment, the number of divisions of the yoke 14 is eight as an example. However, the gist of the present invention is not limited thereto. Further, the configuration example of the yoke divided into a plurality of yokes is not limited to the case of FIG. 1, and the thickness of each of the yokes divided into a plurality of yokes may be formed by mutually different thicknesses.

At the region where the yoke 14 is thick, the magnetic field strength of the corresponding target surface is strong, and at the region where the yoke 14 is thin, the magnetic field strength of the corresponding target surface is weakened. The relationship between the strength of the magnetic field and the thickness of the yoke will be described in detail later.

The yoke 14 is adsorbed only by the magnetic force of the magnet, and has a structure divided into a plurality of structures, whereby the yokes 14 that are divided can be easily removed and exchanged. Therefore, it is possible to easily exchange the yokes 14 having different thicknesses, whereby the control of the magnetic field strength on the surface of the target is easy.

Further, although not shown, the yokes 14 which are divided into the same have the same effect even when the thin ferromagnetic plates are used in a superposed manner. In this case, the magnetic force acting on the yoke 14 of the thin ferromagnetic body is reduced, and the yoke 14 of one thin thin ferromagnetic body can be more easily removed from the magnet unit 10.

In the magnetron sputtering apparatus, in the side of the yoke 14 which is the back side of the magnet unit 10, since it is not necessary to bring the structure close, it is possible to secure a space. Therefore, it is possible to easily exchange the yoke by the human hand and thereby change the magnetic field strength of the surface of the target. Therefore. It is not necessary to move the magnet unit substantially in the opposite direction relative to the target as in the prior art.

Next, the relationship between the thickness of the yoke 14 and the magnetic field strength of the surface of the target will be described. The magnetic field strength at the surface of the target of the general magnet unit 10 shown in Fig. 3 was calculated by the magnetic field analysis software ELF/MAGIC.

The thickness of the yoke 14 of the magnet unit 10 is set to 10 mm in the vicinity of the center portion, and the thickness y of the yoke in the region of the front end portion of 100 mm is changed from 0 mm to 10 mm. The surface of the target (not shown) is located at a position separated from the surface of the magnet unit 10 by 40 mm, and is a magnet from a position where the magnetic flux density vector is slightly parallel to the surface of the target (not shown). The parallel component (symbol 20) of the magnetic flux density at the position of the front end of the unit and 30 mm inside is calculated. Further, the inner magnet 11 and the outer magnet 12 are made of neodymium magnets, and the yoke 14 is made of SUS430.

The calculation results are shown in FIG. As the thickness y of the front end yoke becomes thicker, the magnetic flux density on the surface of the target becomes larger. When the front end yoke thickness a is 6 mm or more, the magnetic flux density on the surface of the target is hardly changed. However, since the yoke of the current end portion is 6 mm or more, it is not magnetically saturated.

In the control of the magnetic field strength on the surface of the target, the yoke thickness can be set in the range of 0 mm to 6 mm. Further, the front end portion yoke thickness a is 0 mm, which means that the yoke 14 is not provided at this region as shown in Fig. 5.

In the example of Fig. 5, as a method for making the magnetic field strength of the front end portion of the magnet unit weaker than the central portion, an example in which the yoke 14 is not provided at the region of the front end portion of the magnet unit 10 is shown. Conversely, in order to make the central portion magnetic field strength weaker than the distal end portion, as shown in FIG. 6, the yoke 14 of the distal end portion may be thickened, and the central portion yoke 14 may be thinned.

In general, the depth of erosion is deeper at a region where the magnetic flux density in the direction parallel to the surface of the target is large, and becomes shallower at a region where the magnetic flux density is small. In the magnet unit of the present embodiment, the erosion of the region where the thickness of the yoke is thickened is deepened, and the erosion of the region where the thickness of the yoke is reduced is shallow. As such, by making a partial change to the yoke thickness, the desired eroded depth shape can be easily obtained.

Next, a description will be given of a sputtering method using the magnetron sputtering apparatus of the present invention. The yoke 14 of the magnet unit 10 is configured, for example, such that the central portion has a uniform thickness and the front end portion is made thinner than the central portion. The substrate 2 is placed on the substrate holder 5 of the chamber 1 to be evacuated, and then a process gas such as an Ar gas is introduced into the chamber so as to be a specific pressure (introduction process).

The magnet unit 10 can be changed without a moving mechanism (not shown). It is changed to be spaced apart from the cathode 4 to reciprocate in a direction parallel to the cathode 4. While the magnet unit 10 is reciprocating by a moving mechanism (not shown), the DC power supply is turned ON, DC power is applied to the target, and sputtering is performed. After a certain period of time, the DC power was turned OFF, and the film formation (film formation process) was completed.

The thickness of the film deposited on the substrate 2 was measured by a measuring means (not shown), and it was confirmed by the measurement result of the measuring means whether or not a desired film thickness distribution (evaluation project) was obtained. When the film thickness distribution is poor and the film thickness of a certain region on the substrate 2 is to be thinned, the yoke of the magnet unit 10 corresponding to the region where the film thickness is to be thinned is changed from a thicker one. For the thinner, reduce the magnetic field strength (change engineering).

On the other hand, when the film thickness of a certain region on the substrate 2 is to be thickened, the yoke of the magnet unit 10 corresponding to the region where the film thickness is to be thickened is exchanged from a thinner to a thinner. Thicker, and enhance the magnetic field strength (change engineering). In this state, the same film formation was performed again, and the film thickness distribution was confirmed. By performing such operations several times in succession, it is possible to obtain a desired film thickness distribution.

(Second embodiment)

Next, a second embodiment of the present invention will be described. In the inner magnet 11 and the outer magnet 12 of the magnet unit 10 shown in FIG. 7A, at the magnetic pole opposite to the target 3, a ferromagnetic body such as iron or SUS430 is followed by an adhesive or the like. The resulting magnetic body 15. The magnetic body 15 connected to the inner magnet 11 and the outer magnet 12 is magnetically connected by the yoke 14 .

The yoke 14 is not fixed by an adhesive or the like, but can be attached only by the adsorption force (magnetic force) of the magnet (the inner magnet 11 and the outer magnet 12). Between the inner magnet 11 and the outer magnet 12, a non-magnetic body 13 is present, and the magnetic body 15 and the non-magnetic body 13 are fixed by an adhesive or a bolt or the like.

In Fig. 7B, the configuration of the magnet unit 10 in the case where the yoke 14 is not present is shown. Since the magnetic body 15 and the non-magnetic body 13 are fixed, even in the case where the yoke 14 is not present, the shape can be maintained. In this case, the inner magnet 11 and the outer magnet 12 are not short-circuited as the magnetic circuit, and the magnetic field strength is the same as that in the case where the yoke 14 is not present in the first embodiment (Fig. 2D).

According to this configuration, since the magnetic body and the non-magnetic body are first connected and assembled, and then the inner magnet and the outer magnet are assembled thereon, the yoke integrated with the prior art is used. The process of assembling the magnets is the same, and the assembly of the magnet units is easy.

The configurations, shapes, sizes, and arrangement relationships described in the above embodiments are merely illustrative of the extent that the present invention can be understood and implemented. Therefore, the present invention is not limited to the embodiments described above, and may be varied in various forms without departing from the scope of the technical idea disclosed in the claims.

1. . . Cavity

2. . . Substrate

3. . . Target

4. . . cathode

5. . . Substrate holder

6. . . Insulator

10. . . Magnet unit

11. . . Inner magnet

12. . . Lateral magnet

13. . . Non-magnetic body

14. . . yoke

15. . . Magnetic body

20. . . Parallel component of magnetic flux

Fig. 1 is a schematic view showing a magnetron sputtering apparatus according to an embodiment of the present invention.

Figure 2A is a front elevational view of the magnet unit of the present invention.

Figure 2B is a cross-sectional view of the A-A of the magnet unit of the present invention.

Figure 2C is a cross-sectional view of the B-B of the magnet unit of the present invention.

Fig. 2D shows a state in which the yoke is not present in Fig. 2A.

Fig. 3 is a view for explaining the analysis of the magnetic field in the magnet unit of the present invention.

Figure 4 is a diagram for showing the magnetic field analysis in the magnet unit of the present invention.

Fig. 5 is a view for explaining a method for making the magnetic field strength of the distal end portion weaker than the central portion in the magnet unit of the present invention.

Fig. 6 is a view for explaining a method for making the magnetic field strength of the distal end portion stronger than the central portion in the magnet unit of the present invention.

7A and 7B are schematic views showing a case where a magnetic body is used in the magnet unit in one embodiment of the present invention.

Fig. 8A is a front elevational view showing the magnet unit of the prior art.

Fig. 8B is a cross-sectional view taken along line A-A of Fig. 8A.

Figure 8C is a cross-sectional view taken along line B-B of Figure 8A.

1. . . Cavity

2. . . Substrate

3. . . Target

4. . . cathode

5. . . Substrate holder

6. . . Insulator

10. . . Magnet unit

11. . . Inner magnet

12. . . Lateral magnet

13. . . Non-magnetic body

14. . . yoke

Claims (3)

A magnetron sputtering apparatus comprising: a cathode having a mounting surface of a target as a surface; and a magnet unit disposed on a back side of the cathode; and (a) the magnet unit An inner magnet formed of a permanent magnet having a magnetic pole surface of one of the polarities facing the cathode side; and a rectangular pole having a polarity opposite to the inner magnet so as to face the inner magnet; An outer magnet formed by a permanent magnet on the cathode side; and a non-magnetic body that fixes the inner magnet and the outer magnet; and a position opposite to the inner magnet facing the cathode and the outer magnet pole surface, and the foregoing a yoke composed of a ferromagnetic material in which the inner magnet and the magnetic pole of the outer magnet are connected, and (b) the yoke has a plate shape, and the longitudinal direction of the magnet is arranged in a rectangular shape. The mutually orthogonal faces are divided into a plurality of, and the yokes that are divided are exchanged, and (c) the magnet unit is With respect to the back surface may be the cathode and is moved in a direction as parallel. The magnetron sputtering apparatus according to claim 1, wherein each of the plurality of yokes divided into a plurality of yokes can be exchanged with a yoke having a different thickness. A sputtering method is a sputtering method using a magnetron sputtering apparatus, and is characterized in that it is provided by using a magnetron sputtering device as described in claim 1 or 2 of the patent application. a film forming process for forming a film; and an evaluation project for evaluating a film thickness formed by the film forming process; and changing the yoke of the magnetron sputtering device according to the evaluation result of the evaluation project Change in thickness.