WO2018068833A1

WO2018068833A1 - Magnet arrangement for a sputter deposition source and magnetron sputter deposition source

Info

Publication number: WO2018068833A1
Application number: PCT/EP2016/074343
Authority: WO
Inventors: Andreas Lopp; Markus Hanika; Hyun Chan Park; Andreas KLÖPPEL
Original assignee: Applied Materials, Inc.
Priority date: 2016-10-11
Filing date: 2016-10-11
Publication date: 2018-04-19
Also published as: CN109844900A; KR20190055219A

Abstract

According to one aspect of the present disclosure, a magnet arrangement (100) for a sputter deposition source is provided. The magnet arrangement comprises a first magnet (110) and a second magnet (120) adapted to confine a plasma in a plasma confinement region (150); and at least one field influencing element (115) comprising a magnetizable material adapted to effect a local displacement of the plasma confinement region toward the at least one field influencing element. According to a second aspect, a magnetron sputter deposition source (400) with a magnet arrangement and a method of depositing a film on a substrate with a magnetron sputter deposition source comprising a magnet arrangement are provided.

Description

MAGNET ARRANGEMENT FOR A SPUTTER DEPOSITION SOURCE AND MAGNETRON SPUTTER DEPOSITION SOURCE

TECHNICAL FIELD

[0001] The present disclosure relates to a magnet arrangement for a sputter deposition source. The present disclosure further relates to a magnetron sputter deposition source for depositing a thin film on a substrate as well as to a method of depositing a thin film on a substrate with a magnetron sputter deposition source. More specifically, the present disclosure relates to a magnet arrangement configured for magnetron sputtering and particularly configured for a rotary target assembly comprising a rotatable target.

BACKGROUND

[0002] Forming thin layers on a substrate with a high layer uniformity is a relevant issue in many technological fields. For example, in the field of thin film transistors (TFTs) thickness uniformity and uniformity of electrical properties of one or more deposited layers may be an issue for reliably manufacturing display channel areas.

[0003] One method for forming a layer on a substrate is sputtering, which has developed as a valuable method in diverse manufacturing fields, for example in the fabrication of TFTs. During sputtering, atoms are ejected from the material of a sputter target by bombardment thereof with energetic particles of a plasma (e.g., energized ions of an inert or reactive gas). The ejected atoms may deposit on the substrate, so that a layer of sputtered material can be formed on the substrate.

[0004] In a magnetron sputter deposition source, a magnet arrangement is typically arranged behind the target material of a sputter target. The magnetic field generated by the magnet arrangement may be suitable for confining the plasma in a plasma confinement region adjacent to a sputter surface of the sputter target. The probability of ionization of the sputtering gas within the plasma confinement region may be greatly increased as compared to the ionization rate outside the plasma confinement region. [0005] However, it may be difficult to achieve a homogeneous and uniform utilization of the target material across the sputter surface of the sputter target. For example, in some cases, some sections of the sputter surface may be more strongly sputtered than other sections, which may lead to an asymmetric utilization of the target.

[0006] Accordingly, providing a magnet arrangement and a magnetron sputter deposition source which can obtain a more uniform utilization of the sputter target may be beneficial.

SUMMARY

[0002] In light of the above, a magnet arrangement for a sputter deposition source, a magnetron sputter deposition source as well as methods of depositing a film on a substrate are provided.

[0003] According to one aspect of the present disclosure, a magnet arrangement for a sputter deposition source is provided. The magnet arrangement includes a first magnet and a second magnet adapted to confine a plasma in a plasma confinement region, and at least one field influencing element including a magnetizable material adapted to effect a local displacement of the plasma confinement region toward the at least one field influencing element.

[0004] According to a further aspect, a magnetron sputter deposition source is provided. The magnetron sputter deposition source includes a rotary target assembly adapted to rotate a sputter target around an axis of rotation, and at least one magnet arrangement connected to the rotary target assembly and adapted to confine a plasma in a plasma confinement region adjacent to a sputter surface of the sputter target. The magnet arrangement includes a first magnet and a second magnet, and at least one field influencing element including a magnetizable material adapted to effect a local displacement of the plasma confinement region toward the at least one field influencing element.

[0005] According to yet another aspect, a method of depositing a film on a substrate with a magnetron sputter deposition source including a magnet arrangement is provided. The method includes: Generating a plasma, and confining the plasma in a plasma confinement region adjacent to a sputter surface of a target, wherein the magnet arrangement comprises at least one field influencing element comprising a magnetizable material which effects a local displacement of the plasma confinement region toward the at least one field influencing element.

[0006] Further aspects, advantages, and features of the present disclosure are apparent from the dependent claims, the description, and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described in the following. Some embodiments are depicted in the drawings and are detailed in the description which follows.

[0016] FIG. 1A shows a schematic top view of a magnet arrangement 100 in accordance with embodiments described herein;

[0017] FIG. IB and FIG. 1C show schematic sectional views of the magnet arrangement of FIG. 1A in sectional plane CI (FIG. IB) and in sectional plane C2 (FIG. 1C);

[0018] FIG. 2A shows a schematic top view of a magnet arrangement 200 in accordance with embodiments described herein;

[0019] FIG. 2B and FIG. 2C show schematic sectional views of the magnet arrangement of FIG. 2A in sectional plane C3 (FIG. 2B) and in sectional plane C3 (FIG. 2C);

[0020] FIG. 3 shows a schematic top view of a magnet arrangement 300 in accordance with embodiments described herein; [0021] FIG. 4A and FIG. 4B show a magnetron sputter deposition source 400 according to embodiments described herein in two different sectional planes; and

[0022] FIG. 5 is a flow diagram illustrating a method of depositing a film on a substrate according to embodiments described herein.

DETAILED DESCRIPTION

[0023] Reference will now be made in detail to the various embodiments of the disclosure, one or more examples of which are illustrated in the figures. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment. It is intended that the present disclosure includes such modifications and variations.

[0024] Within the following description of the drawings, the same reference numbers refer to corresponding or to similar components. Generally, only the differences with respect to the individual embodiments are described. Unless specified otherwise, the description of a part or aspect in one embodiment applies to a corresponding part or aspect in another embodiment as well.

[0025] In a sputter deposition apparatus, a plasma may be generated in a sputter chamber under vacuum, i.e. at a sub-atmospheric pressure, e.g. at a pressure of 1 mbar or less. A plasma is to be understood as a quasi-neutral many-particle system in the form of gaseous blends of free electrons and ions as well as possible neutral particles, i.e. atoms, molecules or radicals. Positive ions of the plasma may be attracted by a negative potential applied to a cathode which comprises the sputter target. The positive ions may impinge on the sputter target and knock away small particles that may subsequently precipitate on a substrate to form a layer thereon. The knocking away of the particles from the sputter target is referred to as "sputtering." The plasma may contain ionized gases, which can, for example, be inert gases such as argon, in the event of a non-reactive sputtering. In the event of a reactive sputtering, for example, oxygen may be used alone or in conjunction with an inert gas.

[0026] The ions for the sputtering process may be generated through the collisions of gas atoms and electrons in a glow discharge and may be accelerated toward the sputter target which may be set on a negative potential. To increase the ionization rate and to provide a better localization of the plasma in an area adjacent to the sputter target, magnet arrangements, so-called magnetrons, may be utilized near the sputter target, e.g. on a first side of the sputter target in order to confine and localize the plasma on a second side of the sputter target. The magnetic field generated by the magnets of the magnet arrangement may confine the plasma near a sputter surface of the sputter target.

[0027] The term "magnet arrangement" or "magnetron" as used herein may refer to a unit capable of generating a magnetic field configured to localize a sputter plasma in a plasma confinement region in front of the magnet arrangement. Typically, the magnet arrangement may comprise permanent magnets. In the case of a rotatable sputter target, the magnet arrangement may be arranged inside the sputter target such that charged particles can be trapped within the generated magnetic field in an area outside the sputter target. In the case of a planar sputter target, the permanent magnets may be arranged behind the sputter target such that charged particles can be trapped within the generated magnetic field in an area in front of the sputter target. In some embodiments, the magnet arrangement includes a magnet yoke.

[0028] Through the interaction of the magnetic field generated by the magnet arrangement and the electric field generated by the cathode, the charge carriers in the plasma no longer move primarily parallel to the electric field, but rather along cycloid electron trajectories. As the deflection radii of the electrons are much smaller than the deflection radii of the ions due to their lower mass, the electrons concentrate above the target surface in the plasma confinement region during sputtering. Therefore, the probability that gas atoms are ionized via collisions with electrons is much higher in the plasma confinement region. [0029] The term "plasma confinement region" as used herein may be understood as the region above the magnet arrangement, i.e. adjacent to the sputter surface of the sputter target, with a high plasma density during sputtering due to the described trapping of the electrons, where the magnetic field vectors may be parallel or essentially parallel (e.g., <30° deviation) to the target surface. Ionizations largely occur where the magnetic field vector is parallel to the target surface. The plasma is most dense here, as a result of which the target may be most strongly eroded in this region.

[0030] Both in the case of planar sputter targets and in the case of rotatable sputter targets it may be difficult to uniformly sputter the sputter target. For example, rotatable targets may be inhomogeneously or asymmetrically sputtered in edge or corner regions, where the plasma density may be increased due to a curvature of the magnet in said edge reasons. This effect may lead to an asymmetric erosion of a sputter target, when the magnet arrangement provides a partially straight and partially curved plasma confinement region. When the target is fully eroded at a given point, the target can no longer be used, even if there may still be sufficient material at other points. Further, in the case of a rotatable sputter target, an increased erosion of the target surface may arise in a part of the plasma confinement region which extends parallel to the rotation direction of the sputter target.

[0031] The present disclosure provides a magnet arrangement for magnetron sputter deposition sources which may provide a more uniform utilization of the target so that the lifetime of the sputter target may be increased.

[0032] FIG. 1A shows a magnet arrangement 100 according to embodiments described herein in a plan view. The magnet arrangement 100 includes a first magnet 110 and a second magnet 120. The first magnet 110 and the second magnet 120 may be arranged on a support plate 130, e.g. on a metal plate. [0033] In some embodiments, both the first magnet 110 and the second magnet 120 may be permanent magnets. The first magnet 110 may have a south pole which is directed toward the sputter target, and the second magnet 120 may have a north pole which is directed toward the sputter target, or vice versa. Accordingly, the magnetic field lines 111 may extend from the south pole of the first magnet (or second magnet) to the north pole of the second magnet (or first magnet) for confining the plasma in the plasma confinement region 150.

[0034] FIG. IB is a cross sectional view of the magnet arrangement 100 of FIG. 1A in a first sectional plane CI . FIG. 1C is a cross sectional view of the magnet arrangement 100 of FIG. 1A in a second sectional plane C2. The sectional plane CI intersects a field influencing element 115 which is arranged adjacent to one of the magnets, whereas the sectional plane C2 does not intersect a field influencing element.

[0035] The magnetic field lines 111 extending between the first magnet 110 and the second magnet 120 may generate a plasma confinement region 150 in an area between the first magnet 110 and the second magnet 120 in front of the magnet arrangement. The plasma confinement region 150 may be arranged close to a sputter surface 403 (indicated as a dashed line in FIG. IB and FIG. 1C) of the sputter target. The plasma confinement region 150 may be understood as a region, in which the magnetic field lines 111 run essentially parallel to the sputter surface 403, as is indicated in FIG. IB and FIG. 1C.

[0036] The magnet arrangement 100 according to embodiments described herein further includes at least one field influencing element 115 comprising a magnetizable material. The field influencing element 115 may be adapted to effect a local displacement of the plasma confinement region 150 toward the at least one field influencing element 115.

[0037] As is shown in FIG. 1A, one or more field influencing elements 115 may be arranged adjacent to the first magnet 110, in order to effect a local displacement of the plasma confinement region 150 toward the field influencing element 115, i.e. toward the first magnet 110, respectively. Alternatively or additionally, one or more further field influencing elements may be arranged adjacent to the second magnet, in order to effect a local displacement of the plasma confinement region 150 toward the further field influencing elements, i.e. toward the second magnet, respectively. [0038] The field influencing element 115 may comprise a magnetizable material. In other words, the field influencing element 115 may be magnetized by an external magnetic field, i.e. by the magnetic field generated by the first magnet 110 and/or by the second magnet 120. The magnetizable material may be used to influence the magnetic field of the first magnet and/or of the second magnet. In some embodiments, the field influencing element

115 comprises or consists of a material which responds strongly to an external magnetic field, particularly a ferromagnetic material. For example, the magnetizable material may be a material with a high magnetic permeability, e.g. a magnetic permeability of 2 or more, particularly 10 or more, more particularly 100 or more, or even 300 or more. [0039] In some embodiments, the magnetizable material may be a soft-magnetic material, i.e. a material which does not remain strongly magnetized when the external magnetic field is removed. For example, the magnetizable material may have a low coercivity. In this case, the field influencing element is no permanent magnet, whereas the first magnet and the second magnet may typically be provided as permanent magnets. [0040] In some embodiments, the magnetizable material may comprise or consist of at least one of iron and steel. For example, the field influencing element may be made of a soft-magnetic mild steel, e.g. a ST37 steel, a ferritic steel, or a "soft" (annealed) iron with a low coercivity.

[0041] The field influencing element 115 may be arranged at a close distance to the first magnet 110 or to the second magnet 120, in order to modify the magnetic field generated by the magnet arrangement. For example, the smallest distance between the field influencing element 115 and one of the magnets may be 10 cm or less, particularly 1 cm or less, more particularly 1 mm or less. More particularly, the field influencing element 115 may be provided in direct contact with the first magnet or the second magnet. [0042] In some embodiments which may be combined with other embodiments described herein, the field influencing element 115 may be attached to the first magnet 110 or to the second magnet 120. In the embodiment depicted in FIG. 1A, the field influencing element 115 is attached to the first magnet 110. In some embodiments, a plurality of field influencing elements may be provided, wherein each field influencing element may be attached either to the first magnet or to the second magnet. The magnetic attraction force between the field influencing element and the first (or second) magnet may be sufficiently strong enough to fix the field influencing element to the first (or second) magnet. However, in some embodiments, the field influencing element may be fixed to the first (or second) method via a fixing device, e.g. with an adhesive.

[0043] When the field influencing element 115 is arranged close to or in direct contact with the first magnet 110, the magnetic field lines of the first magnet 110 will be at least partially drawn into the field influencing element 115 which provides a path for the magnetic field lines. As a result, the strength of the magnetic field generated by the first magnet 110 will be at least locally weakened in an area in front of the magnet arrangement between the first magnet and the second magnet. Accordingly, the magnetic field lines extending from the first magnet toward the second magnet are bent toward the field influencing element 115. Therefore, the arrangement of the field influencing element near the first magnet leads to a local shift of the plasma confinement region toward the first magnet, as is schematically depicted in FIG. 1A and in FIG. IB.

[0044] No field influencing element is provided in the cross-sectional plane C2 shown in FIG. 1C. Therefore, the magnetic field lines 111 are not bent toward the first magnet or toward the second magnet in said cross-sectional plane. Rather, the plasma confinement region 150 may be located essentially in the middle between the first magnet and the second magnet, as the field strength of the first magnet may essentially correspond to the field strength of the second magnet in the sectional plane C2. Accordingly, the reversal point of the magnetic field lines 111, where the magnetic field lines are parallel to the sputter surface 403, may have the same distance from the first magnet and from the second magnet.

[0045] When the field influencing element is arranged adjacent to the second magnet 120, the magnetic field lines of the second magnet 120 will be at least partially drawn into the field influencing element which provides a path for the magnetic field lines. As a result, the strength of the magnetic field generated by the second magnet 120 will be at least locally weakened in an area in front of the magnet arrangement between the first magnet and the second magnet. Accordingly, the magnetic field lines extending from the second magnet toward the first magnet will be bent toward the field influencing element. Therefore, the arrangement of the field influencing element adjacent to the second magnet may lead to a local shift of the plasma confinement region toward the second magnet.

[0046] By providing the magnet arrangement with one or more field influencing elements 115 as described above, the plasma confinement region 150 can be locally displaced, e.g. bent or shifted, towards or away from specific surface regions of the sputter target which were previously sputtered in an inhomogeneous or asymmetric way. Accordingly, the target can be sputtered in a more uniform way by providing one or more field influencing elements. Additionally or alternatively, the plasma confinement region 150 which may have an elongated shape can be at least locally curved toward one or more field influencing elements. A plasma confinement region with an essentially constant curvature will lead to a more uniform plasma density and to a more uniform target utilization. Accordingly, the plasma confinement region can be shaped and/or shifted as appropriate by providing the magnet arrangement with one or more field influencing elements in accordance with embodiments described herein.

[0047] The field influencing element may have a considerable influence on the magnetic field, when the field influencing element is directly attached or fixed to one of the first magnet and the second magnet. In this case, the magnetic field lines of the first magnet or the second magnet may be drawn into the field influencing element, weakening the magnetic field outside the field influencing element and deforming the magnetic field lines 111 between the first magnet and the second magnet. For example, the field influencing element may act as a magnetic shunt which at least partially forms a direct bridge between two opposite poles of one of the magnets. [0048] In some embodiments, which may be combined with other embodiments described herein, the at least one field influencing element 115 may extend from a north pole of the first magnet 110 to a south pole of the first magnet 110, or from a north pole of the second magnet 120 to a south pole of the second magnet 120. For example, as is shown in FIG. IB, the field influencing element 115 may extend from the south pole to the north pole of the first magnet 110. In this case, the field influencing element 115 acts as a magnetic shunt of the respective magnet, directly connecting the north pole of the magnet with the south pole of the magnet. The magnetic field generated by the respective magnet may be considerably weakened. A local asymmetry between the magnetic fields of the first magnet and of the second magnet can be induced, and the plasma confinement region can be locally shifted away from the strong magnet (which does not have the shunt in a given sectional plane) toward the weakened magnet (which has the shunt attached thereto in the given sectional plane).

[0049] In some embodiments, which may be combined with other embodiments described herein, the at least one field influencing element 115 may be a metal sheet, particularly a steel sheet such as a soft-magnetic mild steel sheet. A metal sheet can be easily attached to the first magnet or to the second magnet at specific positions. For example, the metal sheet may be applied to a side surface of the first magnet or of the second magnet, and may locally cover the first magnet or the second magnet from the south pole to the north pole.

[0050] The influence of the field influencing element on the magnetic field may depend on the thickness of the metal sheet. In particular, a thick metal sheet attached to a magnet may have a stronger effect on the magnetic field than a thin metal sheet. Accordingly, the thickness of the metal sheet may be chosen depending on the local displacement of the plasma confinement region to be achieved. In some embodiments, the thickness of the metal sheet may be 1 mm or more and 5 mm or less, particularly 2 mm or more and 4 mm or less, more particularly about 3 mm. The thickness of a metal sheet is measured in a thickness direction of the metal sheet perpendicular to the sheet plane. [0051] In some embodiments, which may be combined with other embodiments described herein, the magnet arrangement may include a plurality of field influencing elements. Each field influencing element may be arranged adjacent to the first magnet or adjacent to the second magnet. For example, some of the field influencing elements may be attached to the first magnet, in order to locally shift the plasma confinement region toward the first magnet, and some of the field influencing elements may be attached to the second magnet, in order to locally shift the plasma confinement region toward the second magnet.

[0052] By alternately attaching field influencing elements to the first magnet and to the second magnet along a length direction of the magnet arrangement, the plasma confinement region may be alternately shifted toward the first magnet and toward the second magnet. A plasma confinement region following an undulating or meandric path can be provided.

[0053] An embodiment of a magnet arrangement 200 including a plurality of field influencing elements 115 is shown in FIG. 2A, FIG. 2B, and FIG. 2C.

[0054] FIG. 2A shows a magnet arrangement 200 for a magnetron sputter deposition source according to embodiments described herein in a top view. FIG. 2B shows the magnet arrangement 200 of FIG. 2A in a first sectional view (in sectional plane C3), and FIG. 2C shows the magnet arrangement of FIG. 2A in a second sectional view (in sectional plane C4).

[0055] The magnet arrangement 200 includes a first magnet 110 and a second magnet 120. The first magnet 110 and the second magnet 120 may be provided on a support plate 130, e.g. on a metal plate. A part of a sputter target 402 may be arranged in front of the magnet arrangement 200. In some embodiments, the sputter target 402 may be a rotatable target, particularly a cylindrical target.

[0056] A pole of the first magnet 110 which is directed toward the sputter target 402 may have a first polarity, and a pole of the second magnet 120 which is directed toward the sputter target 402 may have a second polarity opposite to the first polarity. For example, the south pole 112 of the first magnet 110 and the north pole 123 of the second magnet 120 may be directed toward the sputter target 402, i.e. away from the support plate 130 (see FIG. 2B), or vice versa.

[0057] In some embodiments, the first magnet 110 may be an inner magnet extending linearly in a length direction L of the magnet arrangement 200, and/or the second magnet 120 may be an outer magnet which surrounds the first magnet 110, particularly along a closed path. The closed path may have a rectangular shape. For example, the outer magnet may have a rectangular shape, and the inner magnet may have the shape of a bar which extends inside the outer magnet along the length direction L of the magnet arrangement.

[0058] The first magnet 110 (which may be provided as an inner magnet) and the second magnet 120 (which may be provided as an outer magnet) may be configured to confine a plasma in a closed-loop plasma confinement region 150. The plasma confinement region 150 may be located in front of the magnet arrangement 200 in an area between the first magnet 110 and the second magnet 120, as is depicted in the top view of FIG 2A. Therein, a first section 151 of the plasma confinement region may be generated by the magnetic field lines between the inner magnet and a first longitudinal wall 153 of the outer magnet, and a second section 152 of the plasma confinement region may be generated by the magnetic field lines between the inner magnet and a second longitudinal wall 154 of the rectangular outer magnet.

[0059] As is illustrated in the sectional views of FIG. 2B and FIG. 2C, a part of the sputter target 402 (not shown in FIG. 2A) may be arranged in front of the magnet arrangement 200. The plasma confinement region 150 may be arranged adjacent to the sputter surface 403 of the sputter target 402.

[0060] In some embodiments, which may be combined with other embodiments disclosed herein, the plurality of field influencing elements may include one or more first field influencing elements 215 arranged adjacent to the first magnet 110 for effecting a local displacement of the plasma confinement region 150 toward the first magnet 110, respectively, and/or one or more second field influencing elements 225 for effecting a local displacement of the plasma confinement region 150 toward the second magnet 120, respectively.

[0061] The field influencing elements may be configured to locally displace the plasma confinement region 150 toward the respective field influencing element, respecitvely. For example, a first field influencing element may be arranged adjacent to the first magnet, in order to locally weaken the magnetic field of the first magnet in a first field region, and a second field influencing element may be arranged adjacent to the second magnet, in order to locally weaken the magnetic field of the second magnet in a second field region spaced- apart from the first field region.

[0062] The first field influencing elements may be configured as magnetic shunts which locally connect two points of the first magnet having an opposite polarity, and the second field influencing elements may be configured as magnetic shunts which locally connect two points of the second magnet having an opposite polarity.

[0063] In some embodiments, the first magnet 110 is an inner magnet extending linearly in a length direction L of the magnet arrangement. The first field influencing elements 215 may be attached to one or two longitudinal side surfaces 211 of the inner magnet and face toward the outer magnet, which may surround the inner magnet. The first field influencing elements 215 may be attached to one or two longitudinal side surfaces 211 of the inner magnet at regular intervals such that the inner magnet is periodically weakened in the length direction L of the magnet arrangement. Accordingly, the plasma confinement region 150 may be periodically shifted toward the inner magnet along the path of the plasma confinement region 150 around the inner magnet. A plasma confinement region with an undulating path can be provided.

[0064] In some embodiments, first field influencing elements are attached to both longitudinal side surfaces of the first magnet at corresponding positions such as to face in opposite directions. [0065] A first distance Dl between two adjacent first field influencing elements 215 in the length direction L of the magnet arrangement may be 3 cm or more and 10 cm or less, particularly 4 cm or more and 6 cm or less, more particularly about 5 cm. Alternatively or additionally, the length of the first field influencing elements 215 in the length direction of the magnet arrangement may be 3 cm or more and 10 cm or less, particularly 4 cm or more and 6 cm or less, more particularly about 5 cm. In some embodiments, the first distance Dl between two adjacent first field influencing elements may essentially correspond to the length of the first field influencing elements. A plasma confinement region 150 following an undulating path with an essentially constant wavelength may be provided. The sputter target may be more uniformly sputtered.

[0066] In some embodiments, which may be combined with other embodiments described herein, the second magnet 120 is an outer magnet which may surround the first magnet along an essentially rectangular path. In this case, the second magnet has two longitudinal walls (first longitudinal wall 153 and second longitudinal wall 154) extending in the length direction L of the magnet arrangement parallel to the inner magnet, and two short walls extending in a width direction. The second field influencing elements 225 may be attached to one or two longitudinal side surfaces 221 of the outer magnet and face toward the inner magnet or away from the inner magnet. For example, the second field influencing elements 225 may be attached to the outer side surface of the first longitudinal wall 153 and to the outer side surface of the second longitudinal wall 154 facing away from the inner magnet, as is shown in FIG. 2A. Alternatively, the second field influencing elements may be attached to the inner side surface of the first longitudinal wall 153 facing toward the inner magnet and to the inner side surface of the second longitudinal wall 154 facing toward the inner magnet.

[0067] The second field influencing elements 225 may be attached at regular intervals in the length direction of the magnet arrangement. The plasma confinement region 150 may be periodically displaced toward the outer magnet along the path of the plasma confinement region 150. A plasma confinement region following an undulating path can be provided. [0068] In some embodiments, second field influencing elements are attached to both outer (or both inner) longitudinal side surfaces 221 of the second magnet at corresponding positions in the length direction L, and/or at regular intervals.

[0069] A second distance D2 between two adjacent second field influencing elements 225 in the length direction L of the magnet arrangement may be 3 cm or more and 10 cm or less, particularly 4 cm or more and 6 cm or less, more particularly about 5 cm. Alternatively or additionally, the length of the second field influencing elements 225 in the length direction L of the magnet arrangement may be 3 cm or more and 10 cm or less, particularly 4 cm or more and 6 cm or less, more particularly about 5 cm. In some embodiments, the second distance D2 between two adjacent second field influencing elements may essentially correspond to the length of the second field influencing elements. A plasma confinement region following an undulating path with an essentially constant wavelength may be provided. Accordingly, the sputter target may be more uniformly sputtered.

[0070] In some embodiments, which may be combined with other embodiments described herein, first field influencing elements 215 and second field influencing elements 225 may be alternately arranged in the length direction of the magnet arrangement. An alternate arrangement of first field influencing elements 215 and second field influencing elements 225 may lead to a plasma confinement region 150 following an undulating or meandric path between the first magnet and the second magnet. This is because the first magnet and the second magnet are alternately locally weakened in the length direction L of the magnet arrangement so that the plasma confinement region is alternately displaced toward the second magnet and toward the first magnet.

[0071] In the embodiment shown in FIG. 2A, the first magnet 110 is an inner magnet which extends between the first longitudinal wall 153 and the second longitudinal wall 154 of the rectangular second magnet in the length direction L. First field influencing elements and second influencing elements may be alternately attached to the first longitudinal wall 153 of the outer magnet and to the inner magnet in order to confine a plasma in a first section 151 of the plasma confinement region having an undulating shape. First field influencing elements and second influencing elements may be alternately attached to the second longitudinal wall 154 of the outer magnet and to the inner magnet in order to confine a plasma in a second section 152 of the plasma confinement region having an undulating shape.

[0072] In some embodiments, first field influencing elements may be attached to a first end portion of the first longitudinal wall 153 and of the second longitudinal wall 154 of the outer magnet, in order to increase the radius of curvature of the plasma confinement region in a first turnaround region between the first section 151 and the second section 152 of the plasma confinement region. First field influencing elements may also be attached to a second end portion of the first longitudinal wall 153 and of the second longitudinal wall 154 of the outer magnet, in order to increase the radius of curvature of the plasma confinement region in a second turnaround region between the first section 151 and the second section 152 of the plasma confinement region. An asymmetric erosion of the sputter target in the turnaround regions of the plasma can be reduced.

[0073] The extension of the undulations of the plasma confinement region may be adjusted by providing an appropriate distance between adjacent first field influencing elements 215 and adjacent second field influencing elements 225 in the length direction L of the magnet arrangement. In some embodiments, the first distance Dl between two adjacent first field influencing elements 215 in a length direction L of the magnet arrangement may be 3 cm or more and 10 cm or less, and the second distance D2 between two adjacent second field influencing elements 225 in the length direction L of the magnet arrangement may be 3 cm or more and 10 cm or less. The first field influencing elements and the second influencing element may be arranged at constant intervals, respectively. In some embodiments, a distance between two field influencing elements in the length direction may essentially correspond to the lengths of the field influencing elements in the length direction L. [0074] In some embodiments, the first field influencing elements 215 may by attached to the first magnet 110, and the second field influencing elements 225 may be attached to the second magnet 120.

[0075] In some embodiments, the first field influencing elements 215 may be provided as a metal sheet, e.g. a steel sheet, attached to the first magnet 110, respectively, and/or the second field influencing elements 225 may be provided as a metal sheet, e.g. a steel sheet, attached to the second magnet 120, respectively.

[0076] The thickness of the first field influencing elements 215 and/or the thickness of the second field influencing elements 225 may be 1 mm or more and/or 5 mm or less.

[0077] A length of the first field influencing elements 215 and/or a length of the second field influencing elements 225 in the length direction L of the magnet arrangement may be 10 mm or more and 100 mm or less, particularly 30 mm or more and 70 mm or less, more particularly about 50 mm, respectively.

[0078] The first field influencing elements 215 and the second field influencing elements 225 may comprise a magnetizable material, particularly a ferromagnetic material, more particularly a soft-magnetic material.

[0079] In some embodiments, the first field influencing elements 215 extend at least partially or entirely from the south pole 112 of the first magnet to the north pole 113 of the first magnet in a height direction H of the magnet arrangement. For example, a height of the first field influencing elements 215 may essentially correspond to a height of the first magnet.

[0080] In some embodiments, the second field influencing elements 225 may extend at least partially or entirely from the south pole 122 of the second magnet to the north pole 123 of the second magnet in the height direction of the magnet arrangement. For example, the height of the second field influencing elements 225 may essentially correspond to a height of the second magnet 120. [0081] The first field influencing elements 215 may be configured as magnetic shunts which locally connect the south pole of the first magnet with the north pole of the first magnet, respectively. The second field influencing elements 225 may be configured as magnetic shunts which locally connect the south pole of the second magnet with the north pole of the second magnet, respectively, so that the respective magnet is locally weakened.

[0082] FIG. 3 shows a magnet arrangement 300 according to embodiments described herein in a top view. The magnet arrangement 300 essentially corresponds to the magnet arrangement 200 shown in FIG. 2A so that reference can be made to the above explanations which are not repeated here.

[0083] The magnet arrangement 300 includes a first magnet 110 provided as an inner magnet which extends linearly in a length direction L of the magnet arrangement 300. The magnet arrangement 300 further includes a second magnet 120 provided as an outer magnet which surrounds the inner magnet along a closed path. The closed path may have a rounded shape, e.g. an oval shape or the shape of a rectangle with rounded corners.

[0084] In the top view of FIG. 3, a plasma confinement region 150 which extends along a closed path is provided between the inner magnet and the outer magnet. First field influencing elements 215 and second field influencing elements 225 are alternately arranged along the plasma confinement region, in order to locally shift the plasma confinement region to the inner magnet and to the outer magnet. The first field influencing elements 215 are configured as magnetic shunts which are attached to the inner magnet at regular intervals in the length direction L, and the second field influencing elements 225 are configured as magnetic shunts which are attached to the outer magnet along sections of the plasma confinement region where no first field influencing elements 215 are arranged.

[0085] FIG. 4A shows a sectional view of a magnetron sputter deposition source 400 in a first sectional plane, and FIG. 4B shows the magnetron sputter deposition source of FIG. 4A in a second sectional plane. [0086] The magnetron sputter deposition source 400 includes a rotary target assembly 401 adapted to rotate a sputter target 402 around an axis of rotation A, and at least one magnet arrangement connected to the rotary target assembly 401 and adapted to confine a plasma in a plasma confinement region 150 adjacent to a sputter surface 403 of the sputter target 402. The magnet arrangement may have some features or all the features of any of the magnet arrangements 100, 200, 300 described above, so that reference can be made to the above explanations which are not repeated here.

[0087] A more uniform utilization of the sputter target can be achieved, when the sputter target 402 is rotated around the axis of rotation during sputtering, while the plasma is confined in the plasma confinement region by the magnet arrangement, which does not rotate in correspondence with the sputter target. The at least one magnet arrangement may be arranged inside the sputter target 402. The sputter target may have a cylindrical shape.

[0088] As is shown in FIG. 4A, the plasma confinement region 150 is located near the sputter surface 403 of the sputter target 402. A substrate 410 arranged at a distance from the magnetron sputter deposition source 400 may be coated with a thin layer.

[0089] The substrate 410 can be continuously moved during coating past the magnetron sputter deposition source 400 ("dynamic coating"), or the substrate 410 may rest essentially at a constant position during coating ("static coating"). In a static deposition process, the substrate 410 may remain stationary during coating. It is to be noted that the term "static" deposition process does not exclude any movement of the substrate as would be appreciated by a skilled person. For example, according to embodiments described herein, static sputtering can include, for example, a stationary substrate position during deposition (without any substrate movement), an oscillating substrate position during deposition, an average substrate position that is substantially constant during deposition, a dithering substrate position during deposition and/or a wobbling substrate position during deposition. Accordingly, a static deposition process can be understood as a deposition process with a stationary position, a deposition process with a static position, or a deposition process with a partially static position of the substrate. [0090] The examples described herein can be utilized for deposition on large area substrates, e.g. for lithium battery manufacturing or electrochromic windows. For example, the substrate may have a surface of 0.5 m² or more, particularly 1 m² or more in some embodiments. According to some examples, a large area substrate can be GEN 4.5, which corresponds to about 0.67 m² substrates (0.73x0.92m), GEN 5, which corresponds to about 1.4 m² substrates (1.1 m x 1.3 m), GEN 7.5, which corresponds to about 4.29 m² substrates (1.95 m x 2.2 m), GEN 8, which corresponds to about 5.3m² substrates (2.16 m x 2.46 m), or even GEN 10, which corresponds to about 9.0 m² substrates (2.88 m x 3.13 m). Even larger generations such as GEN 11, GEN 12 and/or corresponding substrate areas can similarly be implemented.

[0091] The term "substrate" as used herein shall particularly embrace inflexible substrates, e.g., glass plates. The present disclosure is not limited thereto and the term "substrate" may also embrace flexible substrates such as a web or a foil.

[0092] Sputtering can be used in the production of displays. In more detail, sputtering may be used for the metallization such as the generation of electrodes or buses. Sputtering is also used for the generation of thin film transistors (TFTs). Sputtering may also be used for the generation of the ITO (indium tin oxide) layer. Sputtering can also be used in the production of thin-film solar cells. A thin- film solar cell includes a back contact, an absorbing layer, and a transparent and conductive oxide layer (TCO). The back contact and the TCO layer can be produced by sputtering whereas the absorbing layer may be made in a chemical vapour deposition process.

[0093] The sputter target 402 may be made of or include at least one material selected from the group including: aluminum, silicon, tantalum, molybdenum, niobium, titanium, indium, gallium, zinc, tin, silver and copper. Particularly, the target material can be selected from the group including indium, gallium and zinc.

[0094] It is to be noted that the axis of rotation A of the rotary target assembly 401 is typically parallel to the length direction L of the magnet arrangement. The axis of rotation A is perpendicular to the sectional planes of FIG. 4A and FIG. 4B. The magnet arrangement may include a first magnet 110, e.g. an inner magnet, and a second magnet 120, e.g. an outer magnet, wherein the first magnet 110 and the second magnet 120 may be directed toward a coating side of the magnetron sputter deposition apparatus where the substrate 410 is arranged.

[0095] In some embodiments, the magnet arrangement may be curved in a sectional plane perpendicular to the axis of rotation A, wherein the curvature of the magnet arrangement may be adapted to a curvature of the cylindrical sputter target 402, as is indicated in FIG. 4A. For example, the inner magnet may be provided at a first angular coordinate, and the first and second longitudinal walls 153, 154 of the outer magnet may be provided at a second and a third angular coordinate, respectively, wherein an angle between the first angular coordinate and the second and third angular coordinates may be 10° or more, respectively.

[0096] The magnet arrangement may include a plurality of field influencing elements which are attached to the first magnet and/or to the second magnet for locally displacing the plasma confinement region.

[0097] In the sectional plane depicted in FIG. 4A, first field influencing elements 215 are attached to both longitudinal side surfaces of the inner magnet so that the first section 151 and the second section 152 of the plasma confinement region 150 are locally shifted toward the inner magnet.

[0098] In the sectional plane depicted in FIG. 4B, second field influencing elements 225 are attached to the first longitudinal walls 153 and second longitudinal wall 154 of the outer magnet so that a first section 151 of the plasma confinement region is shifted toward the first longitudinal wall 153 of the outer magnet, and a second section 152 of the plasma confinement region is shifted toward the second longitudinal wall 154 of the outer magnet.

[0099] First field influencing elements 215 and second field influencing elements 225 may be alternately attached to the first magnet and to the second magnet in the longitudinal direction in order to confine the plasma in a plasma confinement region 150 which follows a closed-loop meandric path.

[00100] The magnet arrangement may be pivotable around the axis of rotation A. The pivot movement of the magnet arrangement may be independent of the rotation of the sputter target around the axis of rotation A. For example, in some embodiments, the magnet arrangement may be configured to "wobble" between a first angular position and a second angular position. A more uniform layer can be deposited on the substrate 410, when the magnet arrangement is moved during sputtering.

[00101] According to some embodiments described herein, a plurality of magnetron sputter deposition sources, each having a rotatable sputter target, may be provided for coating large area substrates. In many embodiments, the plurality of deposition sources is arranged in an array. In particular, for static large-area substrate deposition, it is possible to provide a one-dimensional array of deposition sources that are linearly arranged or that are alternatively arranged along a curved line, e.g. in a bow-like setup. Typically, the number of deposition sources is between 2 and 20, more typically between 9 and 16 per coating area.

[00102] In some embodiments, the deposition sources are spaced apart from each other equidistantly. It is further beneficial that the length of the sputter targets is slightly longer than the length of the substrate to be coated.

[00103] According to a further aspect of the present disclosure, a method of depositing a thin film on a substrate with a magnetron sputter deposition source is provided.

[00104] FIG. 5 is a flow diagram which illustrates the method of depositing a film on a substrate according to embodiments described herein. In box 510, a plasma is generated. In box 520, the plasma is confined in a plasma confinement region 150 adjacent to a sputter surface 403 of a sputter target 402, wherein the magnet arrangement 100 comprises at least one field influencing element 115 comprising a magnetizable material which effects a local displacement of the plasma confinement region 150 toward the at least one field influencing element 115. The generation of the plasma and the confinement of the plasma may be executed simultaneously or successively.

[00105] In some embodiments, a plurality of field influencing elements is provided, wherein each field influencing element effects a local displacement of the plasma confinement region 150 toward the respective field influencing element. A local displacement as used herein may be understood as a shift of a part of the plasma confinement region which is arranged close to the respective field influencing element even closer toward the respective field influencing element.

[00106] By arranging first field influencing elements which are attached to the first magnet and second field influencing elements which are attached to the second magnet in an alternate manner, a plasma confinement region having a closed-loop meandric shape can be provided and the target surface can be utilized more uniformly.

[00107] While the foregoing is directed to embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

1. A magnet arrangement (100, 200, 300) for a sputter deposition source, comprising: a first magnet (110) and a second magnet (120) adapted to confine a plasma in a plasma confinement region (150); and at least one field influencing element (115) comprising a magnetizable material adapted to effect a local displacement of the plasma confinement region (150) toward the at least one field influencing element (115).

2. The magnet arrangement of claim 1, wherein the magnetizable material is a soft- magnetic material, particularly a material comprising at least one of iron and steel.

3. The magnet arrangement of claim 1 or 2, wherein the at least one field influencing element (115) is a metal sheet, particularly a steel sheet.

4. The magnet arrangement of claim 3, wherein a thickness of the metal sheet is 1 mm or more and 5 mm or less, particularly wherein the thickness of the metal sheet is about 3 mm.

5. The magnet arrangement of any of claims 1 to 4, wherein the at least one field influencing element (115) is attached to the first magnet (110) or to the second magnet (120).

6. The magnet arrangement of claim 5, wherein the at least one field influencing element (115) extends from a north pole of the first magnet (110) to a south pole of the first magnet (110) or from a north pole of the second magnet (120) to a south pole of the second magnet (120).

7. The magnet arrangement of any of claims 1 to 6, wherein the at least one field influencing element (115) is configured as a magnetic shunt which connects two points of the magnet arrangement having an opposite polarity.

8. The magnet arrangement of any of claims 1 to 7, wherein a plurality of field influencing elements (115) is provided, the plurality of field influencing elements comprising first field influencing elements (215) arranged adjacent to the first magnet (110) for effecting a local displacement of the plasma confinement region (150) toward the first magnet (110), respectively, and/or second field influencing elements (225) for effecting a local displacement of the plasma confinement region (150) toward the second magnet (120), respectively.

9. The magnet arrangement of claim 8, wherein the first magnet (110) is an inner magnet extending linearly in a length direction (L) of the magnet arrangement, and wherein the second magnet (120) is an outer magnet which surrounds the first magnet (110) along a closed path, particularly along a rectangular path.

10. The magnet arrangement of claim 9, wherein first field influencing elements (215) are attached to one or two longitudinal side surfaces (211) of the inner magnet facing toward the outer magnet, and/or wherein second field influencing elements (225) are attached to one or two longitudinal side surfaces (221) of the outer magnet facing toward the inner magnet or facing away from the inner magnet.

11. The magnet arrangement of any of claims 8 to 10, wherein the first field influencing elements (215) and the second field influencing elements (225) are alternately arranged in order to provide a plasma confinement region (150) extending along an undulating path.

12. The magnet arrangement of claim 10 or 11, wherein a first distance (Dl) between two adjacent first field influencing elements (215) in a length direction (L) of the magnet arrangement is 3 cm or more and 10 cm or less, and/or wherein a second distance (D2) between two adjacent second field influencing elements (225) in the length direction (L) of the magnet arrangement is 3 cm or more and 10 cm or less.

13. A magnetron sputter deposition source (400), comprising: a rotary target assembly (401) adapted to rotate a sputter target (402) around an axis of rotation (A); and at least one magnet arrangement (100, 200, 300) according to any of claims 1 to 12 connected to the rotary target assembly (401) and adapted to confine a plasma in a plasma confinement region (150) adjacent to a sputter surface (403) of the sputter target (402).

14. The magnetron sputter deposition source of claim 13, further comprising a sputter target (402) rotatably held by the rotary target assembly (401), wherein the at least one magnet arrangement (100) is arranged inside the sputter target(402) and pivotable around the axis of rotation (A).

15. A method of depositing a film on a substrate with a magnetron sputter deposition source comprising a magnet arrangement of any of claims 1 to 12, comprising: generating a plasma; and confining the plasma in a plasma confinement region (150) adjacent to a sputter surface (403) of a sputter target (402), wherein the magnet arrangement comprises at least one field influencing element (115) comprising a magnetizable material which effects a local displacement of the plasma confinement region (150) toward the at least one field influencing element (115).