JPH07166346A - Magnetron sputtering device - Google Patents

Abstract

PURPOSE:To adjust sputtering over the entire surface of a target and the thickness of the film formed on a substrate by disposing plural permanent magnets rotating behind the target freely approachably and recedably to and from the rear surface of the target on the side facing the neighborhood of the central part of the rear surface. CONSTITUTION:The plural permanent magnets 8 are freely rotatably disposed behind the target 6 facing the substrate with eccentricity from the center of the target 6 to form a magnetic field of a closed loop circulating the surface of the target 6. The permanent magnets 8 are supported by supporting members 13, 14 via a base 9. These supporting members 13, 14 are mounted at a rotary stage 12 rotated by a motor 15. The side of the permanent magnets 8 facing the neighborhood of the central part of the rear surface of the target 6 is made freely approachably and recedably to and from the rear surface when the supporting member 14 is lifted by a suitable means. The sputtering over the entire surface of the target 6 and the thickness of the film formed on the substrate are, therefore, adjusted by inclining the permanent magnets 8 and the need for changing the design of the permanent magnets 8 is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetron sputtering apparatus mainly used for forming a thin film on a substrate in a semiconductor or electronic device manufacturing process.

[0002]

2. Description of the Related Art In the manufacturing process of semiconductors and electronic devices,
When forming a thin film on a substrate, the magnetron sputtering method is often used because of its easy handling and good controllability. An outline of an apparatus used for this is as shown in FIG. 1, in which a substrate b and a circular or rectangular target c of a substance to be formed are arranged in a vacuum chamber a so as to face each other.
A discharge gas such as Ar is supplied into the vacuum chamber a through a discharge gas inlet i.
In addition, the inside of the vacuum chamber a is evacuated from the vacuum exhaust port j to maintain a constant depressurized state, and a negative voltage is applied to the target c side to cause discharge. Gas molecules (ions) generated by this discharge are accelerated by a negative voltage and are incident on the target c, knocking out atoms on the target surface, and some of the atoms that fly out in all directions by the cosine law are deposited on the substrate b. To form a thin film. h is a target electrode, k is a DC power supply, l is a substrate holder, and m is a magnetic field line. A magnet d is arranged behind the target c, and a magnetic field for confining electrons is formed in front of the target c to generate magnetron discharge, thereby increasing the film formation rate. As the magnet d,
A permanent magnet or electromagnet is used, but the discharge efficiency is highest at the position where the vertical component of the magnetic field on the target surface is 0 (point A in the figure), and the target around point A is the most sputter. To be done. This part is usually called an erosion area. In this portion, the electrons gradually ionize while making an E × B drift. Unless the magnetic field is made so as to form a closed loop, a difference in ion density distribution will occur in the erosion region. Creating an open loop magnetic field results in less discharge at lower pressures than in the closed loop case.

In an electromagnet cathode using an electromagnet as the magnet d, the coil for generating a magnetic field is double or triple,
The position and area of the erosion region can be changed by controlling the direction and magnitude of the current flowing through each coil. Therefore, it is possible to sputter the entire surface of the target c. Also, by optimizing the current control,
The film thickness formed on the substrate can be made uniform.

When a permanent magnet is used as the magnet d, it cannot be controlled like the above electromagnet. Therefore, as shown in the sectional views of FIGS. 2 and 3, by moving the permanent magnet, the same effect can be obtained. ing. FIG. 2 shows a permanent magnet in which an inner magnet e having a fan-shaped portion and an outer magnet f are assembled so that a fan-shaped erosion region is obtained. The permanent magnet is rotated with respect to a target electrode h with a center of an arc of the fan-shaped portion as a rotation center g. By doing so, the fan-shaped erosion region moves over the entire surface of the target c, and the entire surface is sputtered. The film thickness distribution can be adjusted by adjusting the central angle (arc length) of the fan-shaped portion. In the case of FIG. 3, an annular inner magnet n and an outer magnet o are assembled and eccentrically rotated with respect to the target electrode h so that the annular erosion region moves over the entire surface of the target c and the entire surface is sputtered. To be done. By changing the amount of eccentricity, the film thickness distribution can be adjusted, albeit slightly.

[0005]

When the magnet d is an electromagnet, the greatest merit is that it is possible to form erosion regions of various diameters by changing the current amount and the current direction of the magnet d without changing the hardware. However, there is a drawback that it is difficult to rotate the electromagnet and the central portion of the target c is not sputtered. Atoms sputtered in the erosion region are deposited on such a portion that is not sputtered, and this is peeled off to become dust, which is not preferable because it deteriorates the film quality. In addition, the electromagnet requires a large coil to generate a strong magnetic field, and has a larger volume and mass than the permanent magnet. In addition, a current control circuit is required, which increases the cost.

When the magnet d is a permanent magnet, there is no problem like an electromagnet, but hardware must be changed to change the diameter of the erosion region. For example, in the case of FIG. 2, it is necessary to adjust the fan-shaped angle (the length of the arc) in order to control the film thickness distribution, and several magnets were made to perform an experiment in order to obtain the optimum film thickness distribution. This is not preferable because it requires too much labor and cost. Also, FIG.
In this case, when the magnet d is fixed and discharged, a circular erosion region is formed on the surface of the target c, and by rotating the magnet eccentrically, it is possible to determine the concentric circular erosion region from the residence time of the erosion region on the target surface. Two erosion areas are completed. The cross-sectional shape of the target c in this case is as shown in FIG. 4, and the sputter amounts of the inner erosion region and the outer erosion region are almost the same, so that the film thickness distribution is thick near the center of the substrate and goes to the peripheral portion. The thinner it gets. The distribution can be adjusted by changing the amount of eccentricity of the magnet, but only a slight adjustment can be made, and basically the diameter of the magnet must be changed, so that adjustment is not easy.

An object of the present invention is to provide a magnetron sputtering apparatus using a permanent magnet capable of sufficiently adjusting the film thickness distribution without changing the magnet and capable of sputtering the entire surface of the target.

[0008]

According to the present invention, a target is provided facing a substrate, and a plurality of permanent magnets rotating along the target are provided behind the target to generate a closed loop magnetic field in front of the target. In a magnetron sputtering device to be formed, the above-mentioned object is achieved by providing the plurality of permanent magnets so that the permanent magnets can be moved toward and away from the back surface of the target on the side facing the central portion of the back surface. I chose Part of the above object can also be achieved by partially interposing a magnetic material between the plurality of permanent magnets and the target to partially weaken the magnetic field strength on the surface of the target.

[0009]

[Operation] Similar to normal sputtering, when a discharge gas is introduced into the vacuum chamber to maintain a reduced pressure and a negative voltage is applied to the target electrode, the magnetic field of the permanent magnet rotating behind the target causes magnetron discharge. Occurs,
The thickness of the magnetic body interposed between the permanent magnet and the target by tilting the permanent magnet by moving the side of the permanent magnet facing the center of the back surface of the target closer to or away from the back surface. By changing the depth, it is possible to change the effective magnetic field inside and outside the target surface to change the ion distribution.Since the amount of spatter is proportional to the amount of ion, the erosion area is changed to sputter normally. It is possible to sputter the central part of the target, which is difficult to sputter, and thus to sputter the entire surface of the target and freely adjust the film thickness distribution.

[0010]

Embodiments of the present invention will be described with reference to the drawings.
In FIG. 5, reference numeral 1 denotes a vacuum chamber provided with a vacuum exhaust port 2 connected to a vacuum pump and an inlet port 3 for introducing a discharge gas such as Ar gas. Inside the vacuum chamber 1, A substrate 5 such as a silicon wafer supported by a substrate holder 4 and a circular or rectangular target 6 made of a substance to be deposited are arranged to face each other. The target 6 is fixed on a target electrode 7 connected to a DC power supply 18 or a high frequency power supply. Behind the target 6, a plurality of permanent magnets 8 mounted on a base 9 are rotatably provided along the target 6, and a closed loop magnetic field 1 around the surface of the target 6 is provided.
6 is formed. As shown in FIG. 6, the permanent magnet 8 is composed of a disk-shaped inner magnet 8a and an annular outer magnet 8b that surrounds the disk-shaped inner magnet 8a at regular intervals 10 and the center of the magnet 6 is the target 6. Eccentric to the center 11 of the
It was made to rotate around. The permanent magnet 8 can be formed in a triple or more annular shape by using three or more large and small annular shapes, and the inner magnet 8a can also be formed in an annular shape.

With such a structure, it is difficult to adjust the film thickness by changing the distribution of the magnetic field even if the permanent magnet 8 is rotated.
In the present invention, the side of the permanent magnet 8 facing the central portion of the back surface of the target 6 is provided so as to be able to move toward and away from the back surface so that the permanent magnet 8 is tilted and the entire surface of the target 6 is tilted. And the film thickness formed on the substrate 5 was adjusted. To further explain this, the entire diameter of the permanent magnet 8 is set to 1/2 or more of the diameter of the target 6, and the permanent magnet 8 is placed behind the target electrode 7 as shown in FIG. 7, for example. The target 6 provided
The supporting members 13 and 14 support the disk-shaped rotary stage 12 which is rotated by the motor 15 so as to coincide with the center 11 of the. These support members 13 and 14 swingably support the permanent magnet 8, and when the support member 14 near the center 11 of the target 6 is lifted and lowered by an appropriate means such as a cylinder, a motor, or a screw, the back surface of the target 6 is reached. In contrast, the permanent magnet 8 approaches and separates, and the magnetic field distribution on the surface of the target 6 is changed. That is, when the support member 14 is pulled upward in the drawing, the magnetic field on the surface of the target 6 becomes weaker in the central portion than in the peripheral portion, and the ion density in the central portion is weakened than in the peripheral portion, so that the substrate It is possible to reduce the film thickness deposited in the central portion of No. 5. Normally, the thickness of the central portion of the substrate 5 tends to be thicker than that of the peripheral portion,
By rotating the permanent magnet 8 away from the target 6 and rotating it, the film thickness can be made uniform without changing the design of the magnet. Further, since the magnetic field on the surface of the target 6 relatively moves due to the inclination of the permanent magnet 8, and the sputtering region moves accordingly, it is possible to perform sputtering over the entire surface of the target 6.

The objective of adjusting the film thickness distribution of the present invention can be achieved also by partially interposing a magnetic material 17 between the permanent magnet 8 and the target 6 as shown in FIGS. it can. In this case, a fan-shaped iron or other magnetic body 1 is formed on the surface of the permanent magnet 8 corresponding to the vicinity of the center 11 of the target 6.
7 is attached to the permanent magnet 8 by the magnetic body 17.
The magnetic field leaking from the target to the surface of the target 6 is weakened, and when the permanent magnet 8 is rotated about the center 11 of the target 6, the center portion of the target 6 is rotated in the same manner as when the permanent magnet 8 is tilted as described above. Since the magnetic field is weaker than that of the peripheral portion, the ion density of the central portion is weakened as compared with the peripheral portion, and the film thickness deposited on the central portion of the substrate 5 is reduced without changing the design of the permanent magnet 8. obtain. The structure of the permanent magnet 8 is the same as that shown in FIG. As shown in FIG. 10, the magnetic body 17 may be of a tapered shape in which the portion corresponding to the central portion of the annular permanent magnet 8 is thin and the thickness thereof increases toward the portion corresponding to the peripheral portion. In this case, the intensity distribution of the magnetic field on the surface of the target 6 can be gradually reduced from its periphery to its center. By the way, in the above embodiment, the magnetic body 17 is attached to the surface of the permanent magnet 8, but it may be attached to the back surface of the target electrode 7.

[0013]

As described above, according to the present invention, a plurality of permanent magnets rotating behind the target of the magnetron sputtering apparatus are provided on the back surface of the target on the side facing the central portion of the back surface. Since it is provided so that it can approach and separate freely, the magnetic field at the center of the target can be weakened to freely adjust the film thickness distribution, and the structure for approaching and separating without the need to change the design of the permanent magnet is simple and relatively inexpensive. There is an effect that it can be manufactured, and also by partially interposing a magnetic material between the plurality of permanent magnets and the target to partially weaken the magnetic field strength of the surface of the target, the same as the above. The effect is obtained.

[Brief description of drawings]

FIG. 1 is a cutaway side view of a conventional example.

FIG. 2 is a plan view of a conventional permanent magnet.

FIG. 3 is a plan view of another conventional permanent magnet.

FIG. 4 is an explanatory view of the consumption state of the target in the case of FIG.

FIG. 5 is a cutaway side view of the embodiment of the present invention.

6 is a plan view of a portion 6-6 in FIG.

FIG. 7 is a side view of an essential part of a specific embodiment of the present invention.

FIG. 8 is a side view of an essential part of the embodiment of the invention described in claim 3;

9 is a plan view of FIG.

FIG. 10 is a side view of the essential parts of another embodiment of the invention as set forth in claim 3;

[Explanation of symbols]

1 vacuum tank 5 substrate
6 Target 8, 8a, 8b Permanent magnet 11 Center 1
2 rotating stage 16 magnetic field 17 magnetic material

Claims (3)

[Claims] 1. A magnetron sputtering apparatus in which a target is provided facing a substrate, and a plurality of permanent magnets rotating along the target are provided behind the target to form a closed loop magnetic field in front of the target. A magnetron sputtering apparatus, wherein the plurality of permanent magnets are provided so as to be able to move toward and away from the back surface of the target on the side facing the vicinity of the center of the back surface of the target. 2. The target is formed in a substantially circular shape, and a rotary stage is provided so as to be rotatable along the back surface of the target, and is eccentric from the center of rotation of the rotary stage to 1/2 or more of the diameter of the target. A plurality of permanent magnets arranged in concentric circles having a diameter of 10 mm, and the plurality of permanent magnets can be moved toward and away from the back surface of the target on the side facing the vicinity of the center of the back surface. The magnetron sputtering apparatus according to claim 1, wherein the magnetron sputtering apparatus is attached to the rotary stage. 3. A magnetron sputtering apparatus in which a target is provided facing a substrate, and a plurality of permanent magnets rotating along the target are provided behind the target to form a closed loop magnetic field in front of the target. A magnetron sputtering apparatus characterized in that a magnetic material is partially interposed between the plurality of permanent magnets and the target to partially weaken the magnetic field strength on the surface of the target.