JP2020029577A - Sputtering apparatus - Google Patents

Abstract

To provide a technology capable of increasing an ionization rate of a sputtered particle during sputtering by enhancing a plasma density of a facing plasma at a center part of a cylindrical target, in a sputtering apparatus of forming a rotary magnetic field in a target using the cylindrical target.SOLUTION: A sputtering apparatus comprises: a cylindrical target 6 with an inner diameter T of 200 mm or more; a high-frequency power source for applying high-frequency power to the cylindrical target 6; and first and second cylindrical magnetic circuits forming part 8, 9 which are arranged so as to face each other by sandwiching the cylindrical target 6 between them at an outer side of an outer peripheral surface of the cylindrical target 6 and are configured to rotate along the outer peripheral surface of the cylindrical target 6 by a rotation driving mechanism. An outer diameter A of each of the first and second magnetic circuit forming parts 8, 9 with respect to an inner diameter T of the cylindrical sputtering target 6 is set to satisfy T≥A.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an apparatus for forming a film by sputtering, and more particularly to a technique of a sputtering apparatus for forming a film using a cylindrical sputtering target (hereinafter, appropriately referred to as a “target”).

  In recent years, various devices (semiconductors, electronics, displays, solar cells, etc.) have been improved in performance and miniaturized.

  In order to manufacture such a device, a high-quality thin film forming technique that generates few particles in a vacuum is important.

  As such a thin film forming technique, a magnetron type sputtering apparatus and a facing target type sputtering apparatus are conventionally known.

  However, the magnetron sputtering apparatus has a problem in that particles having high kinetic energy collide with the substrate surface during film formation and cause deterioration in film quality.

  On the other hand, the facing target type sputtering system has a structure in which a pair of targets face each other and the substrate is set on the side of the target, so that particles having high kinetic energy during the film formation are prevented from colliding with the substrate surface. Thus, a high-quality thin film can be formed.

  However, in a facing target type sputtering apparatus having a structure in which a pair of targets face each other, a target material adheres to a portion other than the substrate and cannot be used.

  On the other hand, a hollow cathode type sputtering method using a cylindrical target or the like is also known, but even with this method, the entire surface of the target is not uniformly sputtered, so that the utilization efficiency of the target is not good.

  To solve this problem, conventionally, a cylindrical target is used, a magnet for forming a magnetic field is arranged on the back side of the target, and this magnet is rotated concentrically with the target to form a rotating magnetic field in the target. Has been proposed.

  According to the sputtering apparatus having such a configuration, since the entire surface of the target can be sputtered, the utilization efficiency of the target can be improved.

  However, in a conventional sputtering apparatus that uses a cylindrical target and forms a rotating magnetic field in the target, the plasma density near the inner surface of the target due to the magnetron plasma is high, and the plasma density of the opposing plasma in the center of the cylindrical target is high. , There is a problem that the ionization rate of sputtered particles during sputtering is low.

  In particular, in a sputtering apparatus for wafer sizes of 200 mm and 300 mm, the diameter of the cylindrical target needs to be increased, so that there is a problem that this tendency becomes strong.

JP-A-10-008246

  The present invention has been made in view of such problems of the related art, and an object of the present invention is to provide a sputtering apparatus that forms a rotating magnetic field in a target using a cylindrical target. It is an object of the present invention to provide a technique capable of increasing the ionization rate of sputtered particles at the time of sputtering by increasing the plasma density of the opposing plasma at the center of the target.

The present invention made in order to achieve the above object is a sputtering apparatus for forming a film on a substrate in a vacuum, comprising: a cylindrical target having an inner diameter T of 200 mm or more; And a power source for applying the electric power to the cylindrical target. The power source is arranged outside the outer peripheral surface of the cylindrical target so as to face the outer surface of the cylindrical target, and is rotated along the outer peripheral surface of the cylindrical target by a rotation drive mechanism. And at least one pair of cylindrical magnetic circuit forming portions, and the outer diameter A of the pair of opposed cylindrical magnetic circuit forming portions with respect to the inner diameter T of the cylindrical target is T ≧ A. And a sputtering apparatus configured to apply the electric power to a portion on a side opposite to a stage on which the substrate of the cylindrical target is arranged.
The present invention is also effective when the pair of opposed magnetic circuit forming portions is attached to a yoke member made of a magnetic material having a U-shaped cross section.
According to the present invention, the pair of cylindrical magnetic circuit forming portions facing each other is also effective when the inner diameter B is 100 mm or more.
The present invention is also effective when the thickness Y of each of the pair of opposed cylindrical magnetic circuit forming portions is 10 mm or more.
The present invention is also effective when the length L of the pair of opposed cylindrical magnetic circuit forming portions is 40 mm or more.
In the present invention, the rotation drive mechanism is also effective when configured to rotate about a rotation axis at a different position from the rotation axis of the cylindrical target.

  In the present invention, at least a pair of cylindrical magnetic circuit forming portions are disposed so as to face each other with the inner diameter T of the cylindrical target outside the outer peripheral surface of the cylindrical target having a diameter of 200 mm or more, The rotary drive mechanism is configured to rotate along the outer peripheral surface of the cylindrical target, and the outer diameter A of the pair of cylindrical magnetic circuit forming portions with respect to the inner diameter T of the cylindrical target is such that T ≧ A. Since it is provided, it is possible to increase the magnetic field strength of the opposing magnetic field in the central portion of the cylindrical target and improve the plasma density of the opposing plasma generated in the central portion of the target, thereby enabling the The ionization rate of sputtered particles can be increased.

1A and 1B are schematic views showing the configuration of an embodiment of a sputtering apparatus according to the present invention, wherein FIG. 1A is a partial cross-sectional front view, and FIG. -A line sectional view (A) and (b): perspective views showing examples of first and second magnetic circuit forming portions used in the present embodiment. Explanatory drawing showing the dimensional relationship of the sputtering apparatus of the present invention (A) and (b): Explanatory diagrams schematically showing the distribution of a magnetic field (magnetic flux) generated by the first and second magnetic circuit forming portions of the present embodiment and the distribution of plasma generated in the present embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  1A and 1B are schematic views showing the configuration of an embodiment of a sputtering apparatus according to the present invention. FIG. 1A is a partial cross-sectional front view, and FIG. 2) is a sectional view taken along line AA.

  FIGS. 2A and 2B are perspective views showing examples of the first and second magnetic circuit forming portions used in the present embodiment.

  As shown in FIG. 1A, the sputtering apparatus 1 of the present embodiment has a vacuum film forming chamber 2 in which a substrate 20 is arranged on a stage 2a.

The vacuum film forming chamber 2 is connected to a vacuum exhaust device (not shown) and configured to introduce a process gas such as an argon gas.
The vacuum film forming chamber 2 of the present embodiment is grounded.

  A sputtering chamber 4 is provided on the deposition surface side (for example, upper part) of the substrate 20 in the vacuum deposition chamber 2.

This sputtering chamber 4, a cylindrical backing plate 5 and the target 6 having an axis of rotation O ₁ extending in a direction (e.g., vertical direction) perpendicular to the surface of the substrate 20 (hereinafter, referred to as "target 6". ) Is provided.

  The sputtering chamber 4 communicates with the vacuum film forming chamber 2 so that a discharge space in the same vacuum atmosphere as the vacuum film forming chamber 2 is formed.

  In the present embodiment, the target 6 is provided in close contact with the inside of the backing plate 5, and is configured to apply high-frequency power from the high-frequency power source 7 to the target 6 via the backing plate 5.

  In the case of the present embodiment, a configuration is adopted in which high-frequency power is applied to a portion (particularly, an end) of the target 6 opposite to the stage 2a in the vacuum film formation chamber 2 (FIG. 1A). reference).

This is for the following reason.
That is, the high-frequency power applied to the target 6 serving as the cathode flows through the inner surface of the target 6 toward the vacuum film forming chamber 2 serving as the anode (the lower side in FIG. 1A) through a skin effect.

  In the present embodiment, the high-frequency power is applied to the end of the target 6 opposite to the stage 2 a in the vacuum film forming chamber 2, so that the density of the target 6 is also increased near the end of the rotation drive mechanism 11 of the target 6. High plasma is generated.

  On the other hand, when high-frequency power is applied to the end of the target 6 on the side of the vacuum film formation chamber 2, the high-frequency power is close to the vacuum film formation chamber 2, which is the anode, so that the high-frequency power is applied to the rotary drive mechanism 11 (FIG. When the high-frequency power does not flow to the center of the target 6 and the high-frequency power is applied to the central portion of the target 6, the skin effect causes the anode 6 to serve as the anode in the vacuum film forming chamber 2 (FIG. a), the plasma generated in the vicinity of the end of the target 6 on the side of the rotary drive mechanism 11 (upper side in FIG. 1A) has a low density. It is difficult to be done.

  For this reason, in the present embodiment, high-frequency power is applied to the end of the portion of the target 6 opposite to the stage 2a in the vacuum film forming chamber 2.

  In the vicinity of the outer peripheral surface of the backing plate 5 of the sputtering chamber 4, a pair of first and second magnetic circuit forming portions 8, 9 are provided.

  The first and second magnetic circuit forming portions 8 and 9 of the present embodiment include, for example, a neodymium magnet.

  The first and second magnetic circuit forming portions 8 and 9 have the same configuration, and are formed in a U-shaped or U-shaped cross section using a magnetic material such as iron (Fe). It is attached to a plate-shaped yoke member 10.

  In this case, the first and second magnetic circuit forming portions 8 and 9 are respectively fixed to mounting portions 10b formed by bending both ends of the plate-shaped portion 10a of the yoke member 10 at an angle of, for example, 90 degrees. Are arranged so that portions of different polarities face each other with the sputtering chamber 4 interposed therebetween.

  In the present embodiment, by fixing the first and second magnetic circuit forming portions 8 and 9 to the yoke member 10 as described above, the magnetic field intensity at the central portion of the target 6 is greater than when the yoke member 10 is not used. Can be increased (about 1.5 times).

  Further, the lengths of the first and second magnetic circuit forming portions 8 and 9 can be reduced.

  As the first and second magnetic circuit forming portions 8 and 9 of the present invention, those formed in a cylindrical shape (having an annular cross section) are used.

  In this case, the first and second magnetic circuit forming portions 8 and 9 do not necessarily mean one seamless tubular shape. That is, the cylinder may be composed of a plurality of parts.

  As shown in FIGS. 2A and 2B, the first and second magnetic circuit forming portions 8 and 9 of the present example are formed in a cylindrical shape.

  However, the present invention is not limited to this, and a square tube or a rectangular tube may be used.

First and second magnetic circuit forming unit 8 and 9, each target 6 side surfaces 8a, 9a are formed to be parallel to the rotation axis O ₁ of the backing plate 5 and target 6.

In the present embodiment, a state in which the plate-shaped portion 10a of the yoke member 10 is connected to the drive shaft 11a of the rotary drive mechanism 11, and the plate-shaped portion 10a of the yoke member 10 is arranged parallel to the substrate 20. in it is configured to rotate drive the backing plate 5 and the rotary shaft O ₁ and parallel to the rotation axis O ₂ of the target 6 as the center (see Figure 1 (a)).

In the case of the present invention, although not particularly limited, it is preferable that the rotation axis O ₂ of the rotation drive mechanism 11 does not overlap (offset) with the rotation axis O _{1 of the} backing plate 5 and the target 6. (See FIG. 1B).

With this configuration, the first and second magnetic circuit forming unit 8 and 9, the yoke member 10 by rotating about said rotation axis O _2, the periphery of the sputtering chamber 4 having a target 6 It is designed to rotate.

  According to the present embodiment, as described above, the high-frequency power is applied to the partial end of the target 6 on the side opposite to the stage 2a in the vacuum film forming chamber 2, and the target 6 The density of the plasma generated in the target 6 becomes uniform, and the utilization efficiency of the target 6 can be improved.

FIG. 3 is an explanatory diagram showing a dimensional relationship of the sputtering apparatus of the present invention.
In the present invention, the dimensions are set so that the inner diameter T of the cylindrical target 6 is 200 mm or more.

  The dimensions are set so that the outer diameter A of the first and second magnetic circuit forming portions 8 and 9 is equal to or less than the inner diameter of the cylindrical target 6 (T ≧ A).

  This is because a so-called mirror-type counter magnetic field cannot be formed unless the outer diameter A of the first and second magnetic circuit forming portions 8 and 9 is smaller than the inner diameter of the target 6.

  In the case of the present invention, the magnetic flux of the opposing magnetic field 15 formed between the first and second magnetic circuit forming portions 8 and 9 shown in FIG. Considering the influence of the magnetic flux of the opposed magnetic field 15 on the target 6, the outer diameter A of the first and second magnetic circuit forming parts 8, 9 is 20 mm or more larger than the inner diameter T of the cylindrical target 6. It is preferable to set the dimensions so as to be small.

  When the first and second magnetic circuit forming portions 8 and 9 have a cylindrical shape, the diameter of each outer peripheral portion corresponds to the outer diameter A, but the first and second magnetic circuit forming portions 8 and 9 have the same outer diameter. When the portions 8 and 9 have a rectangular shape including a square, the portions on the side of the rotary drive mechanism 11 and the vacuum film forming chamber 2 of the first and second magnetic circuit forming portions 8 and 9 (FIG. In (), the outer diameter of the upper and lower parts corresponds to the outer diameter A.

  On the other hand, the inner diameters B of the first and second magnetic circuit forming portions 8 and 9 are not particularly limited, but from the viewpoint of securing a necessary magnetic field strength and increasing the plasma density in the central portion of the target 6. Is preferably set to 100 mm or more.

  Further, from the viewpoint of widening the erosion region, it is preferable to further increase the inner diameter B of the first and second magnetic circuit forming portions 8 and 9.

  When the first and second magnetic circuit forming portions 8 and 9 have a cylindrical shape, the diameter of each inner peripheral portion corresponds to the inner diameter B, but the first and second magnetic circuit forming portions 8 and 9 have the same inner diameter. When the shapes of the portions 8 and 9 are rectangular shapes including a square, opposing portions of the inner peripheral portions of the first and second magnetic circuit forming portions 8 and 9 having the rectangular shape (vertical and horizontal directions: For example, the smaller of the distances between the vertical direction and the horizontal direction corresponds to the inner diameter B, and the inner diameter B is preferably set to 100 mm or more.

  On the other hand, the first and second magnetic circuit forming parts 8 and 9 are formed in a cylindrical shape, and are formed around the magnet if the length (height with respect to the surface of the yoke member 10) L of the cylinder is short. When the shape of the magnetic field is small and the length L of the cylinder is long, the shape of the magnetic field formed around the magnet becomes large.

  In the case of the present invention, the length L of the cylindrical first and second magnetic circuit forming portions 8 and 9 is not particularly limited, but the required magnetic field strength of the opposing magnetic field is secured. From the viewpoint of increasing the plasma density in the central portion of the target 6, it is preferable to set each to 40 mm or more.

  On the other hand, from the viewpoint of reducing the size of the device, it is preferable that the length L of the cylinders of the first and second magnetic circuit forming portions 8 and 9 is small.

  Further, the thickness Y of the first and second magnetic circuit forming portions 8 and 9 is not particularly limited, but the required magnetic field strength of the opposing magnetic field is secured to reduce the plasma density in the central portion of the target 6. From the viewpoint of increasing the height, it is preferable to set each to 10 mm or more.

  Furthermore, in the present invention, when the distance between the first and second magnetic circuit forming portions 8 and 9 (the distance between the surfaces 8a and 9a on the target 6 side) is X, the first and second magnetic circuit forming portions 8 and 9 are formed. It is preferable that the length L of the cylinder of the magnetic circuit forming portions 8 and 9 is set so as to satisfy the relationship of X ≦ 400 mm and L ≧ X / 7.5.

  In the present invention, by adopting such a configuration, the magnetic field strength of the opposing magnetic field formed between the first and second magnetic circuit forming portions 8 and 9 can be further increased.

  That is, the opposing magnetic field formed between the first and second magnetic circuit forming portions 8 and 9 becomes weaker as the distance between the opposed magnets between the first and second magnetic circuit forming portions 8 and 9 increases. Since the magnetic flux that has not reached the opposing magnet forms a magnetic field due to self-return, the magnetic field strength of the magnetron magnetic field increases, and the magnetron plasma tends to increase. It is preferable that the distance X between 9 and the length L of the cylinders of the first and second magnetic circuit forming portions 8 and 9 be set so as to satisfy the above-described relationship.

  FIGS. 4A and 4B schematically show the distribution of the magnetic field (magnetic flux) generated by the first and second magnetic circuit forming units of the present embodiment and the distribution of the plasma generated in the present embodiment. FIG.

  In the present embodiment, the N pole of the first magnetic circuit forming section 8 and the S pole of the second magnetic circuit forming section 9 are arranged so as to face each other.

  As a result, in the present embodiment, an opposing magnetic field 15 having magnetic lines of force in the direction from the first magnetic circuit forming section 8 to the second magnetic circuit forming section 9 is generated. The opposing magnetic field 15 is formed so as to penetrate the target 6.

  As described above, since the first and second magnetic circuit forming portions 8 and 9 are formed in a cylindrical shape, the generated opposing magnetic field 15 is formed in a cylindrical shape (a so-called mirror type). It is formed in a cylindrical shape.

  Further, a first magnetron magnetic field 16 is generated inside the cylinder of the first magnetic circuit forming section 8 in a direction from the N pole to the S pole.

  On the other hand, a second magnetron magnetic field 17 in the direction from the N pole to the S pole is generated inside the cylinder of the second magnetic circuit forming portion 9.

  In a state in which such a magnetic field is formed, a process gas is introduced into the vacuum film forming chamber 2 under vacuum while rotating the first and second magnetic circuit forming units 8 and 9, and generated by the high frequency power supply 7. When the applied high-frequency power is applied to the target 6 via the backing plate 5, a discharge is generated, for example, between opposing portions of the inner surface of the target 6, and as shown in FIG. An opposing plasma 30 is generated in the portion.

  The counter plasma 30 is confined inside the counter magnetic field 15 by the above-described cylindrical counter magnetic field 15.

  Further, magnetron plasmas 31 and 32 are generated near the first and second magnetic circuit forming portions 8 and 9 on the inner surface of the target 6 by the above-described first and second magnetron magnetic fields 16 and 17. .

  In the present embodiment, since the first and second magnetic circuit forming portions 8 and 9 are configured to rotate along the outer peripheral surface of the target 6, the counter plasma 30 in a uniform state in the target 6. And magnetron plasmas 31 and 32 are generated.

  Then, sputtering is performed on the inner surface of the target 6 by the argon ions in the facing plasma 30 and the magnetron plasmas 31 and 32 colliding with the inner surface of the target 6.

  In the present embodiment described above, the first and second cylindrical magnetic circuit forming portions 8 and 9 sandwich the target 6 outside the outer peripheral surface of the cylindrical target 6 having an inner diameter T of 200 mm or more. The first and second magnetic circuit forming portions 8 and 9 are arranged so as to face each other and rotate along the outer peripheral surface of the target 6 by the rotation drive mechanism 11 with respect to the inner diameter T of the target 6. Is provided so that T ≧ A, so that the magnetic field strength of the opposing magnetic field 15 at the center of the target 6 is increased to improve the plasma density of the opposing plasma 30 generated at the center of the target 6. Thus, the ionization rate of sputtered particles during sputtering can be increased.

  Note that the present invention is not limited to the above embodiment, and various changes can be made. For example, in the above embodiment, one pair of cylindrical magnetic circuit forming portions facing each other is provided around the cylindrical target. However, the present invention is not limited to this. It is also possible to provide two or more pairs of cylindrical magnetic circuit forming portions that face each other.

  Further, in the above embodiment, the power is applied to the target using the high frequency power supply. However, the present invention is not limited to this, and the power can be applied to the target using the DC power supply. Power can also be applied to the target by combining a power supply and a DC power supply.

1 ... Sputtering apparatus 2 ... Vacuum deposition chamber 4 ... Sputter chamber 5 ... Backing plate 6 ... Cylindrical target 7 ... High frequency power supply (power supply)
8 First magnetic circuit forming section 9 Second magnetic circuit forming section 10 Yoke member 10b Attachment section 11 Rotary drive mechanism 20 Substrate

Claims (6)

A sputtering apparatus for forming a film on a substrate in a vacuum,
A cylindrical target having an inner diameter T of 200 mm or more;
A power supply for applying power to the cylindrical target;
At least one pair arranged outside the outer peripheral surface of the cylindrical target so as to face each other with the cylindrical target interposed therebetween, and configured to rotate along the outer peripheral surface of the cylindrical target by a rotation drive mechanism. Having a cylindrical magnetic circuit forming portion,
An outer diameter A of the pair of opposed cylindrical magnetic circuit forming portions with respect to an inner diameter T of the cylindrical target is provided such that T ≧ A;
A sputtering apparatus configured to apply the electric power to a portion opposite to a stage on which the cylindrical target substrate is arranged.   2. The sputtering apparatus according to claim 1, wherein the pair of opposed cylindrical magnetic circuit forming portions are respectively attached to yoke members made of a magnetic material having a U-shaped cross section.   The sputtering apparatus according to claim 1, wherein each of the pair of opposed cylindrical magnetic circuit forming portions has an inner diameter B of 100 mm or more.   4. The sputtering apparatus according to claim 2, wherein each of the pair of opposed cylindrical magnetic circuit forming portions has a thickness Y of 10 mm or more. 5.   The sputtering apparatus according to any one of claims 2 to 4, wherein the length L of the pair of opposed cylindrical magnetic circuit forming portions is 40 mm or more.   The sputtering apparatus according to any one of claims 1 to 5, wherein the rotation drive mechanism is configured to rotate around a rotation axis at a different position from a rotation axis of the cylindrical target.

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