EP2867916A1

EP2867916A1 - Apparatus for coating a layer of sputtered material on a substrate and deposition system

Info

Publication number: EP2867916A1
Application number: EP12730223.0A
Authority: EP
Inventors: Andreas KLÖPPEL; Markus Hanika; Evelyn Scheer; Konrad Schwanitz; Fabio Pieralisi; Jian Liu
Original assignee: Applied Materials Inc
Current assignee: Applied Materials Inc
Priority date: 2012-07-02
Filing date: 2012-07-02
Publication date: 2015-05-06
Also published as: KR20150037963A; CN104704603A; TWI627297B; KR101920840B1; CN104704603B; JP2015522715A; TW201408804A; JP6113841B2; WO2014005617A1

Abstract

An apparatus (10; 166; 224) for coating a layer of sputtered material on a substrate (12) is described. Said apparatus (10; 166; 224) comprises at least two magnet assemblies (60, 74, 82, 90, 98, 106), wherein each magnet assembly (60, 74, 82, 90, 98, 106) has an outer and an inner magnet polarity. The outer magnet polarity of one of the at least two magnet assemblies (60, 74, 82, 90, 98, 106) is different from an adjacent outer magnet polarity of the other one of the at least two magnet assemblies (60, 74, 82, 90, 98, 106). Further, a deposition system (14) is described which comprises such an apparatus (10; 166; 224).

Description

APPARATUS FOR COATING A LAYER OF SPUTTERED MATERIAL ON A SUBSTRATE AND DEPOSITION SYSTEM

TECHNICAL FIELD OF THE INVENTION

[0001] Embodiments of the present invention relate to an apparatus for coating a layer of sputtered material on a substrate. The apparatus comprises at least two magnet assemblies, wherein each magnet assembly has an outer and an inner magnet polarity. Specifically, embodiments of the present invention relate to a deposition system comprising such an apparatus.

BACKGROUND OF THE INVENTION

[0002] A layer of material can be applied on a substrate by means of a so-called sputtering process. Typically, in such a sputtering process ions within a plasma are used to knock particles out of a target by impingement of the particles on the target. Usually, the substrate is positioned opposite the target. The ions are attracted by a cathode, which can be the target itself or can be placed behind the target, when looking from the substrate into the direction of the target. The particles knocked out of the target are deposited on the substrate to form the layer of sputtered material. It is possible to arrange magnets in the proximity of the target for confinement of the plasma. This is called magnetron sputtering. The magnetic field generated by these magnets superposes the existing electric field and affects the behavior of the electrons in the plasma according to the so-called

Lorentz force. Thereby, the plasma density in the plasma can be systematically controlled particularly in the proximity of the surface of the target. This also increases the number of particles knocked out of the target and, therefore, the deposition rate.

[0003] Apparatuses for coating a layer of sputtered material on a substrate and respective deposition systems are used for a wide variety of deposition purposes. The designs of such apparatuses and systems vary in accordance with the particular requirements of the deposition processes. There are, for example, different kinds of targets and cathodes. With a planar cathode, the coating material to be sputtered is configured in the shape of a flat, planar target, whereas the target surface of a rotatable cathode is curved, being configured, in particular, in the form of a cylinder-like tube. With magnetron sputtering a magnet assembly may be provided together with the target- cathode combination. Such a magnet assembly comprises an outer and an inner magnet polarity which are different from one another and which can form a ring shaped assembly. For example, such a magnet assembly comprises a magnet yoke and several arrangements of magnets, wherein each magnet arrangement has its specific magnet polarity facing towards the plasma. Thereby, an outer magnet ring can have a different magnet polarity facing towards the plasma as compared to an inner magnet arrangement.

[0004] The apparatus for coating a layer of sputtered material on a substrate may be used in a dynamic in-line process in which the material is coated onto a moving substrate. Also, the apparatus may be used in a static deposition process in which the substrate is stationary and does not move. Particularly, for a large area deposition two or more targets or cathodes are arranged side by side in a process chamber, thereby forming a target array and/or cathode array.

[0005] In the sputtering process it is desirable to reach uniform erosions of the targets. It has been found out that the use of a cathode array with multiple cathodes leads to erosion profiles of the targets which show hotrings at the end areas of the targets.

SUMMARY OF THE INVENTION

[0006] In light of the above, an apparatus according to independent claim 1 and a deposition system according to independent claim 13 are provided. Further aspects, advantages, and features of the present invention are apparent from the dependent claims, the description, and the accompanying drawings. [0007] According to an embodiment, an apparatus for coating a layer of sputtered material on a substrate is provided. The apparatus includes at least two magnet assemblies, wherein each magnet assembly has an outer and an inner magnet polarity, wherein the outer magnet polarity of one of the at least two magnet assemblies is different from an adjacent outer magnet polarity of the other one of the at least two magnet assemblies. [0008] According to another embodiment, a deposition system comprising such an apparatus for coating a layer of sputtered material on a substrate is provided. The deposition system includes a process chamber for housing the apparatus.

[0009] According to a further embodiment, an apparatus for coating a layer of sputtered material on a substrate comprises at least two magnet assemblies, wherein each magnet assembly has an outer magnet arrangement and an inner magnet arrangement. In the apparatus an outer magnet arrangement of one of the at least two magnet assemblies has a south pole facing towards the substrate or the plasma, and an adjacent outer magnet arrangement of the other one of the at least two magnet assemblies has a north pole facing towards the substrate or the plasma. According to embodiments of the present invention, it is possible to combine the features of the apparatus of this embodiment with one or more features of other embodiments described herein.

[0010] According to another embodiment, an apparatus for coating a layer of sputtered material on a substrate comprises at least two magnet assemblies, wherein each magnet assembly has an outer magnet arrangement and an inner magnet arrangement. In this apparatus the outer magnet arrangement of one of the at least two magnet assemblies has a first resulting magnet polarity directed towards the substrate, and an adjacent outer magnet arrangement of the other one of the at least two magnet assemblies has a second resulting magnet polarity directed towards the substrate. Thereby, the first resulting magnet polarity and the second resulting magnet polarity are different from each other.

According to embodiments of the present invention it is possible to combine the features of the apparatus of this embodiment with one or more features of other embodiments described herein.

[0011] According to a further embodiment, an apparatus for coating a layer of sputtered material on a substrate comprises at least two magnet assemblies. Each magnet assembly has magnets with a different magnet polarity orientation with respect to each other. Thereby, an outer magnet of one of the at least two magnet assemblies has a different magnet polarity orientation compared to an adjacent outer magnet of the other one of the at least two magnet assemblies. According to embodiments of the present invention it is possible to combine the features of the apparatus of this embodiment with one or more features of other embodiments described herein. According to another embodiment, the term different magnet polarity orientation means that the angle between the magnet polarity orientations of the adjacent outer magnets is greater than 90°. Particularly, the angle between the magnet polarity orientations is greater than 150°, for example 180°.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A full and enabling disclosure, including the best mode thereof, to one of ordinary skill in the art is set forth more particularly in the remainder of the specification, including reference to the accompanying figures wherein:

Fig. 1 shows a schematic representation of an exemplary apparatus for coating a layer of sputtered material on a substrate within an exemplary deposition system in accordance with embodiments described herein;

Fig. 2 shows a schematic representation of a cross section through a rotatable tube cathode to be used in an apparatus for coating a layer of sputtered material on a substrate in accordance with embodiments described herein;

Fig. 3 A shows a schematic representation of magnet assemblies for an exemplary apparatus for coating a layer of sputtered material on a substrate in accordance with embodiments described herein;

Fig. 3B shows another schematic representation of an exemplary apparatus for coating a layer of sputtered material on a substrate in accordance with embodiments described herein;

Fig. 4 shows a schematic representation of a top view on several magnet assemblies of an apparatus for coating a layer of sputtered material on a substrate in accordance with embodiments described herein;

Fig. 5 shows a schematic representation of a further exemplary apparatus for coating a layer of sputtered material on a substrate in accordance with embodiments described herein;

Fig. 6 shows a schematic representation of a cross section through three magnet assemblies which are assigned to a single planar cathode to be used in an apparatus for coating a layer of sputtered material on a substrate in accordance with embodiments described herein; and

Fig. 7 shows a schematic representation of another exemplary deposition system having several cathodes positioned in parallel in accordance with embodiments described herein.

DETAILED DESCRIPTION OF EMBODIMENTS

[0013] Reference will now be made in detail to the various embodiments of the invention, one or more examples of which are illustrated in the figures. Within the following description of the drawings, the same reference numbers refer to same components. Generally, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation of the invention and is not meant as a limitation of the invention. Further, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the description includes such modifications and variations.

[0014] Fig. 1 shows a schematic representation of an apparatus 10 for coating a layer of sputtered material on a substrate 12 within a deposition system 14. Particularly, Fig. 1 shows a cross section through the apparatus 10 and the system 14. The deposition system 14 is a system for coating a layer of sputtered material on a substrate. The term

"substrate" as used herein shall embrace both inflexible substrates, e.g., a wafer, slices of crystal such as sapphire or the like, or a glass plate, and flexible substrates such as a web or a foil.

[0015] The apparatus 10 comprises six targets and /or cathodes 16, 18, 20, 22, 24, and 26 which are in the following referred to as cathodes 16 to 26. The cathodes 16 to 26 are connected to a negative voltage. Each cathode 16 to 26 has the form of a hollow cylinder or a tube, and it is rotatable around its longitudinal axis. Each cathode 16 to 26 is assigned to a target which typically is a solid state body which provides the material for coating the substrate 12 in a sputtering process. Here, the respective target has the form of a hollow cylinder. Further, a magnet assembly is assigned to each cathode 16 to 26. Each of the magnet assemblies comprises a certain number of magnet arrangements which can be an arrangement or a series of permanent magnets. At least one of the magnet series has an outer magnet polarity and at least another one of the magnet series has an inner magnet polarity. The magnet assembly is positioned inside the hollow cylindrical cathode in the proximity of the target so that the magnetic field penetrates through the target. The targets and the magnet assemblies assigned to the cathodes 16 to 26 are not shown in Fig. 1 but will be described in further detail in connection with Fig. 2.

[0016] According to embodiments described herein, an apparatus for coating a layer of sputtered material on a substrate is provided. The apparatus includes at least two magnet assemblies 60, as e.g. illustrated in FIG. 3A. Each magnet assembly 60 has an outer and an inner magnet polarity, wherein the outer magnet polarity of one of the at least two magnet assemblies is different from an adjacent outer magnet polarity of the other one of the at least two magnet assemblies. As shown in FIG. 3B the outer magnet assemblies 364, 368 and 365 in FIG. 3A have a different polarity facing towards the substrate and/or plasma, which is indicated by the different structuring (diagonal vs. vertical) in FIG. 3A.

The outer magnet arrangements form a closed loop by the side ends 356, which surrounds the inner magnet arrangements 366. For example, the inner magnet arrangement 366 of the upper magnet assembly 60 in FIG. 3A can have a north pole facing towards the plasma and/or substrate, and the inner magnet arrangement 366 of the lower magnet assembly 60 in FIG. 3A can have a south pole facing towards the plasma and/or substrate, whereas the outer magnet arrangement 364, 365 and 368 of the upper magnet assembly 60 in FIG. 3A can have a south pole facing towards the plasma and/or substrate and the outer magnet arrangement 364, 365 and 368 of the lower magnet assembly 60 in FIG. 3A can have a north pole facing towards the plasma and/or substrate. [0017] For cathodes arrays without an alternating magnet orientation, the electrons transfer from cathode to cathode, which takes place always in the same direction such that the effect cumulates from cathode to cathode. This leads to crosstalk between all cathodes. As illustrated with respect to FIG. 3 A, this can be avoided by using alternate magnet polarity for at least one pair of neighboring cathodes. With opposite magnet polarity electron drift direction within the magnetron is reversed. With the reversal of drift direction the position of major electron losses is shifted from one side of the turnaround to the other side. Thereby, the efficiency of target usage by providing uniform target erosion over the whole target length for the complete cathode array can be increased.

[0018] Referring back to FIG. 1, according to some embodiments, anodes 28, 30, 32, 34, 36, 38, and 40 can be positioned adjacent to the cathodes 16 to 26. The anodes 28 to 40 can have a cylindrical form. The longitudinal axes of the cathodes 16 to 26 and the anodes 28 to 40 can be positioned in parallel. The anode 28 is positioned at the beginning and the anode 40 at the end of the anode-cathode arrangement within the apparatus 10. The anodes 30 to 38 are positioned between the cathodes 16 to 26 so that the anodes 28 to 40 alternate with the cathodes 16 to 26. Therefore, each of the cathodes 16 to 26 has two adjacent anodes. Each anode 28 to 40 is connected to a positive voltage. It should be clear that the number of cathodes and anodes within the apparatus 10 can be varied and adapted as necessary for a specific application.

[0019] The deposition system 14 according to Fig. 1 comprises a process chamber 42 which houses the apparatus 10. The process chamber 42 can be a vacuum chamber configured to be evacuated through a vacuum flange thereof. A plasma with ions and electrons can be generated within the vacuum chamber adjacent to the cathodes. The ions are used to knock particles out of the targets, and the electrons are used to ionize the plasma. Further, the deposition system 14 comprises chamber shields 44 for shielding the process chamber 42, a presputter shield 46, and mask shieldings 48. According to some implementations, the presputter shield 46 can be connected to the anodes 28 to 40 via a resistance 50. The chamber shields 44 can be connected to ground. A substrate support 52 for holding the substrate 12 is provided in the deposition system 14. The substrate support 52 is positioned with respect to the cathodes 28-30 so that the particles knocked out of the targets can be deposited on the substrate 12. [0020] Fig. 2 shows a schematic representation of a cross section through the rotatable cathode 16 which is used in the apparatus 10 for coating a layer of sputtered material on a substrate. The cathode 16 is shown representatively for the other cathodes 18 to 26 which typically have the same configuration. The cathode 16 comprises a backing tube 54, e.g. a hollow cylinder in the form of a tube. A target 56 is connected to the outer surface of the backing tube 54. The target 56 also has a hollow cylindrical form. The target 56 and the backing tube 54 can rotate in the direction of an arrow 58, i.e. in the clockwise direction. However, they can also rotate in the counterclockwise direction. [0021] A magnet assembly 60 is arranged in the inside of the cathode 16. The magnet assembly 60 can include a circular arc- shaped yoke 62 in which three magnets 64, 66 and 68 are disposed. The magnets 64, 66, and 68 can be magnet arrangements, which are composed of a plurality of single magnets. These single magnets are connected together in a suitable manner. Advantageously, these single magnets are permanent magnets. Each of the magnet arrangements 64 to 68 has a specific magnet polarity. Particularly, these magnet polarities are effective towards the target, the plasma and/or the substrate respectively. The magnet arrangements 64 to 68 can, for example, be characterized by the pole which faces towards the plasma. The pole can be either a south pole or a north pole. Further, the magnet polarities of the magnet arrangements 64 to 68 can be characterized by the types of resulting magnet polarities which are directed towards the target, the plasma and/or the substrate, respectively. The magnet arrangements 64 and 68 are referred to as outer magnet arrangements since they form a ring around the inner magnet arrangement 66. Accordingly, the magnet polarities of the magnet arrangements 64 and 68 are outer magnet polarities. The magnet arrangement 66 is called an inner magnet arrangement since it is positioned in an inner area of the magnet assembly 60 between the outer magnet arrangements 64 and 68. Accordingly, the magnet polarity of the magnet series 66 is an inner magnet polarity. The outer magnet arrangements 64 and 68, respectively, have the same magnet polarity which is different from the magnet polarity of the inner magnet series 66. Fig. 2 shows field lines 70 and 72 of the magnetic field which is set up by the magnet series 64 to 68.

[0022] Fig. 3B shows another schematic representation of an apparatus 10 for coating a layer of sputtered material on the substrate 12. Fig. 3B shows a cross section of the cathodes 16 to 26, whereas other features of the apparatus 10 have been omitted for better overview. The configurations of the single cathodes 16 to 26 correspond to the configuration of the cathode 16 described in Fig. 2. As shown in FIG. 3B, the cathodes 16 to 26 differ in the specification of their respective magnet assembly. According to the embodiment described in connection with Fig. 3B the magnet polarities of the outer magnet arrangements alternate from magnet assembly to magnet assembly. This means that the magnet polarities of the inner magnet series also alternate from magnet assembly to magnet assembly. [0023] In the present embodiment the cathode 16 is an outer cathode at the left end of the row of cathodes 16 to 26. The cathode 16 comprises the magnet assembly 60 with the outer magnet series 64 and 68 and the inner magnet series 66. The outer magnet series 64, 68 have the same outer magnet polarities which are a magnet polarity N. The inner magnet polarity of the inner magnet series 66 is a magnet polarity S which is different from the outer magnet polarities N of the magnet assembly 60. The next cathode in the row of cathodes 16 to 26 is the cathode 18. The cathode 18 is positioned right hand adjacent the cathode 16. The cathode 18 comprises a magnet assembly 74 with outer magnet series 76 and 78 and an inner magnet series 80. The outer magnet series 76 is positioned adjacent the outer magnet series 68 of the neighboring magnet assembly 60. Advantageously, the outer magnet polarity of the outer magnet series 76 is different from the adjacent outer magnet polarity of the magnet series 68. Therefore, the outer magnet polarity of the outer magnet series 76 is the magnet polarity S. Since the outer magnet series 78 has the same outer magnet polarity as the magnet series 76, its outer magnet polarity is also the magnet polarity S. Further, since the inner magnet polarity of the inner magnet series 80 of the magnet assembly 74 is different from its outer magnet polarity, the inner magnet polarity is the magnet polarity N. The next cathode in the row of cathodes 16 to 26 is the cathode 20. The cathode 20 is positioned right hand adjacent the cathode 18. The cathode 20 comprises a magnet assembly 82 with outer magnet series 84 and 86 and an inner magnet series 88. The outer magnet series 84 is positioned adjacent the outer magnet series 78 of the neighboring magnet assembly 74. Advantageously, the outer magnet polarity of the outer magnet series 84 is different from the adjacent outer magnet polarity of the magnet series 78. Therefore, the outer magnet polarity of the outer magnet series 84 is the magnet polarity N. Since the outer magnet series 86 has the same outer magnet polarity as the magnet series 84, its outer magnet polarity is also the magnet polarity N. Further, since the inner magnet polarity of the inner magnet series 88 of the magnet assembly 82 is different from its outer magnet polarity, the inner magnet polarity is the magnet polarity S. The next cathode in the row of cathodes 16 to 26 is the cathode 22. The cathode 22 is positioned right hand adjacent the cathode 20. The cathode 22 comprises a magnet assembly 90 with outer magnet series 92 and 94 and an inner magnet series 96. The outer magnet series 92 is positioned adjacent the outer magnet series 86 of the neighboring magnet assembly 82. Advantageously, the outer magnet polarity of the outer magnet series 92 is different from the adjacent outer magnet polarity of the magnet series 86. Therefore, the outer magnet polarity of the outer magnet series 92 is the magnet polarity S. Since the outer magnet series 94 has the same outer magnet polarity as the magnet series 92, its outer magnet polarity is also the magnet polarity S. Further, since the inner magnet polarity of the inner magnet series 96 of the magnet assembly 90 is different from its outer magnet polarity, the inner magnet polarity is the magnet polarity N. The next cathode in the row of cathodes 16 to 26 is the cathode 24. The cathode 24 is positioned right hand adjacent the cathode 22. The cathode 24 comprises a magnet assembly 98 with outer magnet series 100 and 102 and an inner magnet series 104. The outer magnet series 100 is positioned adjacent the outer magnet series 94 of the neighboring magnet assembly 90. Advantageously, the outer magnet polarity of the outer magnet series 100 is different from the adjacent outer magnet polarity of the magnet series 94. Therefore, the outer magnet polarity of the outer magnet series 100 is the magnet polarity N. Since the outer magnet series 102 has the same outer magnet polarity as the magnet series 100, its outer magnet polarity is also the magnet polarity N. Further, since the inner magnet polarity of the inner magnet series 104 of the magnet assembly 98 is different from its outer magnet polarity, the inner magnet polarity is the magnet polarity S. The next and last cathode in the row of cathodes 16 to 26 is the cathode 26. The cathode 26 is positioned right hand adjacent the cathode 24. The cathode 26 comprises a magnet assembly 106 with outer magnet series 108 and 110 and an inner magnet series 112. The outer magnet series 108 is positioned adjacent the outer magnet series 102 of the neighboring magnet assembly 98. Advantageously, the outer magnet polarity of the outer magnet series 108 is different from the adjacent outer magnet polarity of the magnet series 102. Therefore, the outer magnet polarity of the outer magnet series 108 is the magnet polarity S. Since the outer magnet series 110 has the same outer magnet polarity as the magnet series 108, its outer magnet polarity is also the magnet polarity S. Further, since the inner magnet polarity of the inner magnet series 112 of the magnet assembly 106 is different from its outer magnet polarity, the inner magnet polarity is the magnet polarity N.

[0024] As described above, the alternating polarities of the magnet assemblies in the cathodes of the cathode array reduced crosstalk between cathodes within an array, which may occur with similar magnet assemblies due to collection of some of the electron losses, wherein, in consequence an array electron current is generated which runs along the outer cathodes of the array and jumps from cathode to cathode in the turnarounds of the magnetrons. Accordingly embodiments described herein improve the efficiency of target usage by providing uniform target erosion over the whole target length for the complete cathode array. For the customer, using such an alternate magnet array increases lifetime of the cathodes, thus costs of deposited layers will be decreased as with higher efficiency of target usage more substrates can be coated with the same set of targets.

[0025] Fig. 4 shows a schematic representation of a top view on the neighboring magnet assemblies 60, 74, 82, 90, 98, and 106 of the apparatus 10 for coating a layer of sputtered material on a substrate. The arrangement and configuration of the magnet assemblies 60, 74, 82, 90, 98, and 106 correspond to the embodiment as described in connection with Fig. 3B. Other features of the apparatus 10 have been omitted for a better overview. Fig. 4 shows at the left hand side of the row of parallel magnet assemblies 60, 74, 82, 90, 98, and 106, the magnet assembly 60 with its outer magnet series 64 and 68 and its inner magnet series 66. The outer magnet series 64, 68, respectively, have the outer magnet polarity N and the inner magnet series 66 has the inner magnet polarity S. A reference number 114 refers to the longitudinal axis of the cathode 16 to which the magnet assembly 60 is assigned. The magnet assembly 74, with its outer magnet series 76 and 78 and its inner magnet series 80, is positioned adjacent the magnet assembly 60. The outer magnet series 76, 78, respectively, have the outer magnet polarity S, and the inner magnet series 80 has the inner magnet polarity N. A reference number 116 refers to the longitudinal axis of the cathode 18 to which the magnet assembly 74 is assigned. Next, the magnet assembly 82 with its outer magnet series 84 and 86 and its inner magnet series 88 is positioned adjacent the magnet assembly 74. The outer magnet series 84, 86, respectively, have the outer magnet polarity N and the inner magnet series 88 has the inner magnet polarity S. A reference number 118 refers to the longitudinal axis of the cathode 20 to which the magnet assembly 82 is assigned. Next, the magnet assembly 90 with its outer magnet series 92 and 94 and its inner magnet series 96 is positioned adjacent the magnet assembly 82. The outer magnet series 92, 94, respectively, have the outer magnet polarity S and the inner magnet series 96 has the inner magnet polarity N. A reference number 120 refers to the longitudinal axis of the cathode 22 to which the magnet assembly 90 is assigned. The magnet assembly 98, with its outer magnet series

100 and 102 and its inner magnet series 104, is positioned adjacent the magnet assembly 90. The outer magnet series 100, 102, respectively, have the outer magnet polarity N, and the inner magnet series 104 has the inner magnet polarity S. A reference number 122 refers to the longitudinal axis of the cathode 24 to which the magnet assembly 98 is assigned. Finally, the magnet assembly 106 with its outer magnet series 108 and 110 and its inner magnet series 112 is positioned adjacent the magnet assembly 98. The outer magnet series 108, 110, respectively, have the outer magnet polarity S and the inner magnet series 112 has the inner magnet polarity N. A reference number 124 refers to the longitudinal axis of the cathode 26 to which the magnet assembly 106 is assigned.

[0026] The apparatus 10 with its magnet assemblies 60, 74, 82, 90, 98, 106 is positioned in the process chamber 42. Therefore, the plasma is confined by the magnet assemblies 60, 74, 82, 90, 98, 106, as well. The plasma comprises ions having positive charges and electrons having negative charges. The electrons and their drifts are used to generate further ions within the plasma which shall then knock particles of material out of the targets. This means that the electrons affect the erosion of the targets. Particularly, the drifts of the electrons, and therefore the generation of further ions, shall be influenced by the magnet assemblies 60, 74, 82, 90, 98, 106. The path the plasma flows, particularly in and around the respective magnet assembly 60, 74, 82, 90, 98, 106, or the respective target erosion is called plasma racetrack. For example, the plasma is defined by the configuration of the respective magnet assembly 60, 74, 82, 90, 98, 106. The electrons are exposed to an electrical and a magnetic field. The force which acts on the electrons is the so-called Lorentz force. The Lorentz force is defined by F (Lorentz) = q * (E + v x B), wherein q is the charge of the charged particle (the electron), E is the field strength of the electrical field, v is the velocity of the charged particle, and B is the flux density of the magnetic field.

[0027] Because of the forces which act on the electrons an individual electron drift current is generated for each magnet assembly 60, 74, 82, 90, 98, 106. The direction of the individual electron drift current is defined by the polarities of the inner and outer magnet series of the respective magnet assembly 60, 74, 82, 90, 98, 106, thus the direction of the respective magnetic field. Particularly, the individual electron drift current flows between the outer magnet series and the inner magnet series of the respective magnet assembly 60, 74, 82, 90, 98, 106. Examples of such electron drift currents are indicated in Fig. 4. Fig. 4 shows an electron drift current 126 which is related to the magnet assembly 60, an electron drift current 128 which is related to the magnet assembly 74, an electron drift current 130 which is related to the magnet assembly 82, an electron drift current 132 which is related to the magnet assembly 90, an electron drift current 134 which is related to the magnet assembly 98, and an electron drift current 136 which is related to the magnet assembly 106. The directions in which the electron drift currents 126 to 136 flow is indicated by arrows in Fig. 4. It can be noted that the direction of the individual electron drift current 126 to 136 alternates from magnet assembly to magnet assembly. This results from the alternation of the magnet polarities of the outer and inner magnet series from magnet assembly to magnet assembly. The electron drift currents 126, 130 and 134 run counterclockwise, whereas the electron drift currents 128, 132 and 136 run clockwise. [0028] The plasma confinement along which the respective individual electron drift current flows has two parallel and straight center parts, a left center part 138 and a right center part 140, and two turnarounds, an upper turnaround 142 and a lower turnaround 144. The left center part 138 runs between the left elongated outer magnet series and the elongated inner magnet series, and the right center part 140 runs between the right elongated outer magnet series and the elongated inner magnet series of the respective magnet assembly 60, 74, 82, 90, 98, 106. The upper turnaround 142 connects the center parts 138, 140 at their upper ends and the lower turnaround 144 connects the center parts 138, 140 at their lower ends.

[0029] Typically, the plasma density in the turnarounds 142, 144 is different from the center parts 138, 140. This can lead to differences in the local erosion of the target. The erosion of the target gets non-uniform during the sputtering process. A measure to avoid this is to weaken the magnetic field in the turnarounds 142, 144. For example, this can be reached by applying shunts to the magnet series in the turnarounds 142, 144. Shunts are ferromagnetic metal sheets, for example. This results in a lower target erosion in the turnarounds 142, 144. However, a side effect of the weaker magnetic field in the turnarounds 142, 144 is a weaker local plasma confinement which results in electron losses to surrounding parts of the cathode and its magnet assembly. Particularly, the electron losses are strong at the end of the turnarounds 142, 144 before the electrons of the electron drift current reenter the straight center parts 138, 140. [0030] According to some embodiments, two or more cathodes having magnet assemblies are positioned close to each other so that two adjacent cathodes exert an interaction on each other. These cathodes build a cathode array. However, the adjacency between two cathodes can lead to the effect that the adjacent magnet assembly of the adjacent cathode can collect some of the electron losses. Electrons of the individual electron drift currents of the magnet assemblies flow from one magnet assembly to the adjacent one at the end of the turnarounds. This leads to crosstalk between the adjacent magnet assemblies. The direction and the position of the jumping of electrons from one magnet assembly to the adjacent one depends on the direction of the individual electron drift current, particularly. And, the direction of the individual electron drift current depends on the configuration of the polarities of the outer and inner magnet series of the respective magnet assembly. Accordingly, embodiments described herein, avoid a crosstalk between a plurality of cathodes, a majority of cathodes or all cathodes in a cathode array. This is due to alternating magnet orientations between the magnet assemblies of at least two neighboring cathodes.

[0031] For some embodiments described herein, the effect of the jumping of electrons from one magnet assembly to the adjacent one is shown in Fig. 4. According to the embodiment described in connection with Fig. 4, the direction of the electron drift current

126 of the magnet assembly 60 is counterclockwise. Therefore, electron jumps, i.e. electron crosstalk, take place at the end of the lower turnaround 144 of the magnet assembly 60 from the electron drift current 126 to the electron drift current 128 of the adjacent magnet assembly 74. This crosstalk is indicated by an arrow 146. The direction of the electron drift current 128 of the magnet assembly 74 is clockwise. Therefore, electron jumps take place at the end of the lower turnaround 144 of the magnet assembly 74 from the electron drift current 128 to the electron drift current 126 of the adjacent magnet assembly 60. This crosstalk is indicated by an arrow 148. The crosstalk 146 and the crosstalk 148 are reversed to each other so that these electron losses of the electron drift currents 126, 128 are compensated, in general. Further, electron jumps take place at the end of the upper turnaround 142 of the magnet assembly 74 from the electron drift current 128 to the electron drift current 130 of the adjacent magnet assembly 82. This crosstalk is indicated by an arrow 150. In the next magnet assembly 82 the direction of the electron drift current 130 is again counterclockwise. Electron jumps take place at the end of the upper turnaround 142 of the magnet assembly 82 from the electron drift current

130 to the electron drift current 128 of the adjacent magnet assembly 74. This crosstalk is indicated by an arrow 152. Since the crosstalk 150 and the crosstalk 152 are reversed to each other the electron losses of the electron drift currents 128, 130 are compensated, at least nearly. Electron jumps also take place at the end of the lower turnaround 144 of the magnet assembly 82 from the electron drift current 130 to the electron drift current 132 of the adjacent magnet assembly 90. This crosstalk is indicated by an arrow 154. In the magnet assembly 90 the direction of the electron drift current 132 again is clockwise. Electron jumps take place at the end of the lower turnaround 144 of the magnet assembly 90 from the electron drift current 132 to the electron drift current 130 of the adjacent magnet assembly 82. This crosstalk is indicated by an arrow 156. Since the crosstalk 154 and the crosstalk 156 are reversed to each other, the electron losses of the electron drift currents 130, 132 are compensated, at least nearly. Further, electron jumps take place at the end of the upper turnaround 142 of the magnet assembly 90 from the electron drift current 132 to the electron drift current 134 of the adjacent magnet assembly 98. This crosstalk is indicated by an arrow 158. In the magnet assembly 98 the direction of the electron drift current 134 is counterclockwise. Electron jumps take place at the end of the upper turnaround 142 of the magnet assembly 98 from the electron drift current 134 to the electron drift current 132 of the adjacent magnet assembly 90. This crosstalk is indicated by an arrow 160. Since the crosstalk 158 and the crosstalk 160 are reversed to each other these electron losses of the electron drift currents 132, 134 are compensated, at least nearly. Electron jumps also take place at the end of the lower turnaround 144 of the magnet assembly 98 from the electron drift current 134 to the electron drift current 136 of the adjacent magnet assembly 106. This crosstalk is indicated by an arrow 162. In the magnet assembly 106 the direction of the electron drift current 136 is clockwise. Electron jumps take place at the end of the lower turnaround 144 of the magnet assembly 106 from the electron drift current 136 to the electron drift current 134 of the adjacent magnet assembly 98. This crosstalk is indicated by an arrow 164. Since the crosstalk 162 and the crosstalk 164 are reversed to each other these electron losses of the electron drift currents 134, 136 are compensated, at least nearly.

[0032] The embodiment according to Fig. 4 clearly shows that the alternation of the magnet polarities from magnet assembly to magnet assembly, at least nearly, leads to compensations of the electron losses. The alternating magnet polarities cause a reversion of the direction of the electron drift current from magnet assembly to magnet assembly. This leads to a shifting of the positions of the electron losses from one side of the turnarounds to the other side, which means from the lower turnaround 144 to the upper turnaround 142, and vice versa. [0033] Advantageously, crosstalk, i. e. electron losses, between adjacent cathodes can be avoided according to the present invention. This crosstalk could result from an array electron drift current which runs across or around an array of neighboring cathodes which have similar magnet assemblies. The array electron drift current would flow along the outer cathodes of the cathode array and jump from cathode to cathode in the turnarounds of the magnet assemblies. The array electron drift current would superimpose the individual electron drift currents within the cathodes. Caused by the array electron drift current, the plasma density could be increased in the turnarounds of the magnet assemblies of mainly the inner cathodes of the cathode array. This could lead to an increased local target erosion, particularly at the target positions which are in the proximity of the turnarounds of the magnet assemblies. Therefore, uniform erosions of targets, particularly of targets of the inner cathodes of an array of multiple neighboring cathodes, can be reached according to an advantage of the present invention. Thus, the generation of the array electron drift current is avoided. [0034] Fig. 5 shows a schematic representation of a further exemplary apparatus 166 for coating a layer of sputtered material on the substrate 12. In general, the configuration of the apparatus 166 according to Fig. 5 corresponds to the configuration of the apparatus 10 according to FIG. 3B. Fig. 5 shows a cross section of cathodes 168, 170, 172, 174, 176, and 178, whereas other features of the apparatus 166 have been omitted for better overview. The configurations of the single cathodes 168 to 178 correspond to the configuration of the cathode 16 described with the help of Fig. 2. In contrary to the embodiment described in connection with FIG. 3B in the present embodiment according to Fig. 5 the magnet polarities of the outer magnet series do not alternate from magnet assembly to magnet assembly. In the present embodiment, two neighboring magnet assemblies with adjacent outer magnet polarities of the same magnet polarity, alternate with a magnet assembly having an outer magnet polarity which is different from the adjacent outer magnet polarities of the two neighboring magnet assemblies. Accordingly, FIG. 5 shows a cathode array, wherein two N-S-N cathode assemblies are provided next to each other and form a pair of N-S-N cathodes and one S-N-S cathode is provided next to the pair of N-S-N cathodes. Thereby, the current loop of plasma electrons along or across the entire array is interrupted. In light of the above, according to different embodiments described herein, the cathode array includes at least two magnet assemblies, wherein the outer magnet polarity of one of the at least two magnet assemblies is different from an adjacent outer magnet polarity. Accordingly, at least one alternation in the magnet polarities of outer (and inner) magnet polarities between two neighboring cathodes is provided. Typically, as illustrated with respect to FIGS. 3B and 4 each cathode can have an alternating magnet polarity with respect to a neighboring cathode. It can be understood that a plurality of combinations of alternating options can be provided as long as an alternation in two neighboring cathodes is provided.

[0035] Fig. 6 shows a schematic representation of a cross section through three neighboring magnet assemblies 216, 218, and 220 which are assigned to a single planar cathode 222 to be used in an apparatus 224 for coating a layer of sputtered material on the substrate 12. The cathode 222 is connected to a target 226. The magnet assembly 216 comprises outer magnet series 228 and 230 which have an outer magnet polarity N. Between the outer magnet series 228, 230 the magnet assembly 216 comprises an inner magnet series 232 which has an inner magnet polarity S. The inner magnet polarity S is different from the outer magnet polarity N. An outer magnet series 234 of the magnet assembly 218 is positioned adjacent the outer magnet series 230. The outer magnet series

234 has an outer magnet polarity S which is different from the outer magnet polarity N of the outer magnet series 230. An outer magnet series 236 of the magnet assembly 218 also has the outer magnet polarity S, and an inner magnet series 238 of the magnet assembly 218 has an inner magnet polarity N. The configuration of the third magnet assembly 220 corresponds to the configuration of the first magnet assembly 216. Therefore, outer magnet series 240 and 242 have an outer magnet polarity N and an inner magnet series 244 has an inner magnet polarity S.

[0036] Fig. 7 shows a schematic representation of an exemplary deposition system 14 for coating a layer of sputtered material on the substrate 12. The deposition system 14 comprises the apparatus 10. The apparatus 10 holds the cathodes 16 to 26 and the anodes

28 to 40 which are all positioned in parallel. Fig. 7 illustrates the longitudinal axes 114 to 124 of the cathodes 16 to 26 and the distance 246 between adjacent cathodes. Advantageously, the cathodes are positioned so close to each other that two adjacent cathodes exert an interaction on each other. Preferably, the distance between two adjacent cathodes is less than 500 mm. More preferably, the distance between two adjacent cathodes is between 300 mm and 400 mm, even more preferably between 235 mm and 250 mm. [0037] Advantageously, according to the present invention it is possible to reach a uniform coating of the substrate with the sputtered material. Further advantageously, it is possible to provide for a very uniform erosion profile of the targets which are used for coating. This assures a high efficiency in the use of the targets. The lifetime of a target increases compared to prior art systems. This decreases the costs since more substrates can be coated with one and the same target or set of targets compared to prior art systems. In addition, the deposition system is able to run longer without maintenance or preventive maintenance. Therefore, the uptime of the system is improved which allows for a higher efficiency of the system usage compared to prior art systems. [0038] Particularly, the deposition system according to the present invention is a PVD

(Physical Vapor Deposition) large area deposition system for coating a substrate having a large area. Typically, the deposition system, as well as the apparatus for coating a layer of sputtered material on a substrate, are suitable for a static deposition process in which the substrate is stationary and does not move. However, it is also possible to exert the present invention in a dynamic deposition process in which the substrate is moving. Also, the present invention is suitable for many different types of substrates, for example, the substrate can have a small area. The present invention can be applied to rotatable targets as well as planar targets, to AC (Alternating Current) systems and DC (Direct Current) systems. Preferably, the present invention is applicable for a deposition system and an apparatus for coating a layer of sputtered material on a substrate comprising more than two magnet assemblies. More preferably, these magnet assemblies are arranged side by side.

[0039] According to embodiments described herein, the methods provide a sputter deposition for a positioning of the substrate for a static deposition process. Typically, particularly for large area substrate processing, such as processing of vertically oriented large area substrates, it can be distinguished between static deposition and dynamic deposition. A dynamic sputtering, i.e. an inline process where the substrate moves continuously or quasi-continuously along the deposition source, would be easier due to the fact that the process can be stabilized prior to the substrates moving into a deposition area, and then held constant as substrates pass by the deposition source. Yet, a dynamic deposition can have other disadvantages, e.g. particle generation. This might particularly apply for TFT backplane deposition. According to embodiments described herein a static sputtering can be provided, e.g. for TFT processing, wherein the plasma can be stabilized prior to deposition on the pristine substrate. Thereby, it should be noted that the term static deposition process, which is different as compared to dynamic deposition processes, does not exclude any movement of the substrate as would be appreciated by a skilled person. A static deposition process can include, for example, a static substrate position during deposition, an oscillating substrate position during deposition, an average substrate position that is essentially constant during deposition, a dithering substrate position during deposition, a wobbling substrate position during deposition, a deposition process for which the cathodes provided in one chamber, i.e. a predetermined set of cathodes provided in the chamber, a substrate position wherein the deposition chamber has a sealed atmosphere with respect to neighboring chambers, e.g. by closing valve units separating the chamber from an adjacent chamber, during deposition of the layer, or a combination thereof. Accordingly, a static deposition process can be understood as a deposition process with a static position, a deposition process with an essentially static position, or a deposition process with a partially static position of the substrate. Thereby, a static deposition process, as described herein, can be clearly distinguished from a dynamic deposition process without the necessity that the substrate position for the static deposition process is fully without any movement during deposition.

[0040] According to some embodiments, which can be combined with other embodiments described herein, the embodiments described herein can be utilized for

Display PVD, i.e. sputter deposition on large area substrates for the display market. According to some embodiments, large area substrates or respective carriers, wherein the carriers have a plurality of substrates, may have a size of at least 0.67 m². Typically, the size can be about 0.67m (0.73m x 0.92m - Gen 4.5) to about 8 m² to about 8 m², more typically about 2 m² to about 9 m² or even up to 12 m². Typically, the substrates or carriers, for which the structures, apparatuses, such as cathode assemblies, and methods according to embodiments described herein are provided, are large area substrates as described herein. For instance, a large area substrate or carrier can be GEN 4.5, which corresponds to about 0.67 m² substrates (0.73m x 0.92m), 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 8.5, which corresponds to about 5.7m² substrates (2.2 m x 2.5 m), or even GEN 10, which corresponds to about 8.7 m² substrates (2.85 m x 3.05 m). Even larger generations such as GEN 11 and GEN 12 and corresponding substrate areas can similarly be implemented.

[0041] In light of the above, a plurality of embodiments are described where magnet assemblies in at least on pair of neighboring cathodes of a cathodes array alternate from cathode to cathode with respect to their polarity, i.e. inner and outer magnets form an N-

S-N polarity arrangement in one cathode and a S-N-S polarity arrangement in a neighboring cathode. As shown in FIG. 6, a similar alternation can also be provided from magnet assembly to magnet assembly, e.g. for the case where one cathode has more than one magnet assembly. [0042] Further, a plurality of optional modifications can be provided, which can be provided in addition or alternatively to each other. According to a further embodiment, the at least two magnet assemblies are neighboring magnet assemblies. According to another embodiment, a cross-section of each of the at least two magnet assemblies has two outer magnet polarities and one inner magnet polarity, wherein the inner magnet polarity is different from the outer magnet polarities. According to a further embodiment, the apparatus comprises at least three magnet assemblies. Preferably the apparatus comprises at least five magnet assemblies. According to a further embodiment, adjacent outer magnet polarities of at least two neighboring magnet assemblies of the group of magnet assemblies have the same magnet polarity. According to a further embodiment, at least two neighboring magnet assemblies with adjacent outer magnet polarities of the same magnet polarity alternate with at least one magnet assembly having an outer magnet polarity being different from the adjacent outer magnet polarities of the at least two neighboring magnet assemblies. According to a further embodiment, the outer magnet polarities of the magnet assemblies alternate from magnet assembly to magnet assembly. According to another embodiment, the magnet assemblies are corresponding to one or more cathodes. According to a further embodiment, each cathode is corresponding to one of the magnet assemblies. According to a further embodiment, the distance between two adjacent cathodes is such that the two adjacent cathodes exert an interaction on each other. Preferably the distance between two adjacent cathodes is less than 500 mm. More preferably the distance between two adjacent cathodes is between 300 mm and 400mm.

Even more preferably the distance between two adjacent cathodes is between 235 mm and 250 mm. According to another embodiment, the cathodes are planar cathodes. Preferably the apparatus comprises one single planar cathode. According to another embodiment of the deposition system, the apparatus comprises rotatable cathodes which have longitudinal axes. These longitudinal axes are positioned in parallel. According to a further embodiment of the deposition system, it is a system for coating a layer of sputtered material on a substrate.

[0043] While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

1. An apparatus (10; 166; 224) for coating a layer of sputtered material on a substrate (12), said apparatus (10; 166; 224) comprising: at least two magnet assemblies (60, 74, 82, 90, 98, 106), wherein each magnet assembly (60, 74, 82, 90, 98, 106) has an outer magnet polarity (64, 68, 76, 78, 84, 86, 92, 94, 100, 102, 108, 110) and an inner magnet polarity (66, 80, 88, 96, 104, 112); wherein the outer magnet polarity of one of the at least two magnet assemblies (60, 74, 82, 90, 98, 106) is different from an adjacent outer magnet polarity of the other one of the at least two magnet assemblies (60, 74, 82, 90, 98, 106).

2. The apparatus according to claim 1, wherein the at least two magnet assemblies (60, 74, 82, 90, 98, 106) are neighboring magnet assemblies (60, 74, 82, 90, 98, 106).

3. The apparatus according to any of claims 1 to 2, wherein a cross-section of each of the at least two magnet assemblies (60, 74, 82, 90, 98, 106) has two outer magnet polarities (64, 68, 76, 78, 84, 86, 92, 94, 100, 102, 108, 110) and one inner magnet polarity (66, 80, 88, 96, 104, 112), wherein the inner magnet polarity is different from the outer magnet polarities.

4. The apparatus according to any of claims 1 to 3, wherein said apparatus (10; 166; 224) comprises at least three, preferably at least five magnet assemblies (60, 74, 82, 90, 98, 106).

5. The apparatus according to claim 4, wherein adjacent outer magnet polarities of at least two neighboring magnet assemblies of the group of magnet assemblies have the same magnet polarities.

6. The apparatus according to claim 5, wherein at least two neighboring magnet assemblies with adjacent outer magnet polarities of the same magnet polarity alternate with at least one magnet assembly having an outer magnet polarity being different from the adjacent outer magnet polarities of the at least two neighboring magnet assemblies.

7. The apparatus according to any of claims 1 to 4, wherein the outer magnet polarities of the magnet assemblies (60, 74, 82, 90, 98, 106; 216, 218, 220) alternate from magnet assembly (60, 74, 82, 90, 98, 106; 216, 218, 220) to magnet assembly (60, 74, 82, 90, 98, 106; 216, 218, 220).

8. The apparatus according to any of claims 1 to 7, wherein the magnet assemblies (60, 74, 82, 90, 98, 106; 216, 218, 220) are corresponding to one or more cathodes (16, 18, 20, 22, 24, 26; 222).

9. The apparatus according to claim 8, wherein the cathodes (16, 18, 20, 22, 24, 26) are rotatable cathodes.

10. The apparatus according to any of claims 8 to 9, wherein each cathode (16, 18, 20, 22, 24, 26; 222) is corresponding to one of the magnet assemblies (60, 74, 82, 90, 98, 106; 216, 218, 220).

11. The apparatus according to any of claims 8 to 10, wherein the distance (246) between two adjacent cathodes (16, 18, 20, 22, 24, 26) is such that the two adjacent cathodes (16, 18, 20, 22, 24, 26) exert an interaction on each other, preferably the distance between two adjacent cathodes is less than 500 mm, more preferably between 300 mm and 400mm, even more preferably between 235 mm and 250 mm.

12. The apparatus according to claim 8, wherein the cathodes are planar cathodes (222), preferably said apparatus (224) comprises one single planar cathode.

13. A deposition system (14) comprising an apparatus (10; 166; 224) according to any of claims 1 to 12, and a process chamber (42) for housing the apparatus (10; 166; 224).

14. The deposition system according to claim 13, wherein the apparatus is an apparatus (10; 166; 224) according to any of claims 8 to 11, and wherein the cathodes (16, 18, 20, 22, 24, 26) have longitudinal axes (114, 116, 118, 120, 122, 124) which are positioned in parallel.

15. The deposition system according to any of claims 13 to 14, wherein said system is a system (14) for coating a layer of sputtered material on a substrate (12).