Machine for depositing materials by means of cathode sputtering technology

Abstract

A machine of the type provided with a cathode assembly for depositing material on a substrate by cathode sputtering technology, comprising: a tubular support extending along a first axis, and a plurality of magnetic elements, the plurality of magnetic elements being constrained on the tubular support and spaced apart from each other along the first axis, and wherein each of the magnetic elements has at least one second magnetic orientation axis linking corresponding magnetic poles and comprising an outer side protruding from the tubular support and an inner side constrained to the tubular support, wherein the second axis linking the magnetic poles of each magnetic element is transverse to the first axis of the tubular support, and the polarity of the outer sides of two consecutive magnetic elements on the tubular support is alternating along the first axis; wherein each of the plurality of magnetic elements comprises a plurality of magnets arranged along a spiral line around the first axis of the tubular support, and the tubular support is at least partially made of magnetic or ferromagnetic material.

Description

Technical Field

[0001] The invention relates to the field of machines for depositing materials by means of cathode sputtering technology. Prior art

[0002] It is known to realize machines capable of coating a substrate, usually placed in a vacuum chamber, by depositing on its surface atoms or ions ejected from a solid sacrificial body bombarded by energetic particles. In particular, the emission of atoms or ions from the sacrificial body is caused by a plurality of energetic particles, such as, for example, gas ions in a plasma state, which are caused to hit the sacrificial body, which is therefore also called a "target".

[0003] The target may include all elemental materials or compounds thereof that are deposited on the deposition substrate in both their pure and modified states by chemical reaction with the gas within the vacuum chamber.

[0004] Such machines for depositing materials have a variety of applications, such as those in the industrial field and in the field of scientific research, for example. In the industrial field, such machines can be used for surface coatings of workpieces of different geometric shapes and sizes. For example, in the semiconductor industry, such machines can be used to deposit thin layers of materials such as tungsten, aluminum, titanium, copper, etc. Other uses can be uses related to depositing anti-reflection layers or surface metallization.

[0005] As previously mentioned, the machine for depositing materials by means of the cathode sputtering technique allows the deposition of coating materials on a deposition substrate placed, for example, in a low-pressure chamber, by means of an etching process of a target or, as hereinafter referred to as a "target body" comprising such coating materials. Specifically, during the etching of the target body, the coating material is separated from the target body in the form of atoms, ions or molecular parts and diffuses into the surrounding area, thereby finally adhering to the deposition substrate.

[0006] Target etching occurs due to the use of a highly ionized gas in a "plasma" state, which is interposed between the target and the deposition substrate and is appropriately excited to provide high energy particles intended to strike the target to cause the above-mentioned etching.

[0007] Machines for depositing materials are known, and there is a potential difference (eg several kV) between the target and the deposition substrate. Typically, the target is the cathode (negative electrode) and the substrate or another element is the anode (positive electrode).

[0008] When an inert gas (such as, for example, argon) is filled between the target and the deposition substrate under appropriate pressure conditions (e.g., tens of millitorr), the free electrons in the gas are accelerated away from the negative charge of the cathode, so that they collide with the inert gas atoms and ionize them. In this way, a chain reaction is triggered and a strongly ionized gas, or "plasma," is generated.

[0009] In this case, the ionized atoms of the inert gas are positively charged atoms and are therefore accelerated by electrostatic attraction toward the cathode (in this case, represented by the target body). The ionized atoms collide with the target surface, causing the coating material (atoms or ions) to break away from the target and adhere to the deposition substrate by diffusing in the direction opposite to the direction taken by the target.

[0010] Machines for depositing materials are known and also comprise a plurality of magnets capable of generating a static magnetic field (to form a so-called "magnetron"). These magnets are usually placed below the target, or at any rate on the side of the target opposite to that on which the substrate to be coated is placed, so that the resulting magnetic field interacts with the ionized atoms located in a chamber inserted between the target and the deposition substrate, thus changing the trajectory of the ionized atoms towards the target and increasing the probability of collisions with the subsequent increase in the number of ionized molecules, so as to obtain a higher process yield.

[0011] It must be noted that process "yield" usually means "sputtering yield", which is the ratio of the number of atoms etched from the target to the number of ions incident on the target surface.

[0012] In such cathode sputtering machines comprising magnets (the so-called "magnetron sputtering" process), the magnets can be arranged along a tubular support to generate a magnetic field with radial or axial streamlines relative to the axis of the tubular support itself. In some cases, such a tubular support with the corresponding magnets can be rotated or translated relative to the target in order to allow a given uniformity of the effect generated by the magnetic field.

[0013] This solution can be implemented in the case where, for example, the target and possibly also the substrate to be coated have a cylindrical shape. In this case, we are talking about a cylindrical magnetron sputtering machine.

[0014] Patent US6436252 describes a machine for depositing coating materials by cathode “magnetron” sputtering, comprising a plurality of magnets arranged along a tubular support, apparently made of diamagnetic material, which can be translated relative to a corresponding target having a cylindrical shape.

[0015] The magnets are positioned on the tubular support so that each magnet, together with the two closest magnets, generates two corresponding magnetic fields with "axial" magnetic field lines, i.e. arranged substantially in a plane passing through the axis of the support. It must therefore be observed that the axis linking the north and south poles of each magnet, i.e. the magnetic orientation axis, is arranged in a direction parallel to the axis of the cylindrical support.

[0016] However, known machines for depositing materials have several drawbacks.

[0017] One drawback is the low yield of the process, ie, the low ratio between the number of atoms etched from the target and the number of ions striking the target surface, which increases the time and cost of the process.

[0018] Another drawback is the non-uniform etching of the target. Such problems do not allow the material deposition process to be optimized, since known machines generate a large amount of waste of target element material when the target element is non-uniformly etched.

[0019] Another drawback is the difficulty in adapting the machine dimensions according to the deposition substrate or other parameters of the deposition process. In particular, in the case where the size of the target and the substrate to be coated must be increased, it is usually necessary to design a new machine or a large number of its components in order to adapt the process to the new requirements in terms of size.

[0020] An object of the present invention is to provide a machine for depositing material that is able to increase the yield of the sputtering process.

[0021] Yet another object of the invention is to make the etching process of the target as uniform as possible.Thus, it is an object of the invention to reduce waste during the material deposition process, to increase the effectiveness of the process and to reduce costs.

[0022] Yet another object of the present invention is to provide a machine for depositing material that can easily adapt its own dimensions based on the dimensions of the deposition substrate.

[0023] Yet another object of the present invention is to obtain high deposition rates in order to avoid possible chemical reactions due to the exposure time of the deposition itself required to obtain the desired thickness. Summary of the invention

[0024] These and other objects are achieved by the invention by means of a machine for depositing material according to the invention.

[0025] The machine for depositing material on a substrate according to the invention is a machine for cathode magnetron sputtering, having a cylindrical geometry and of the type provided with a cathode assembly, comprising:

[0026] - a tubular support extending substantially along the first axis and preferably, but not necessarily, at least partially made of a magnetic or ferromagnetic or even paramagnetic but not diamagnetic material;

[0027] a plurality of magnetic elements constrained to the tubular support and spaced apart from one another along at least the first axis or along at least one direction parallel to the first axis, and wherein each of the magnetic elements is provided with an outer side protruding from the tubular support and an inner side facing the axis of this tubular support (and this inner side may for example be constrained to the tubular support itself) and having at least one second magnetic orientation axis linking the respective magnetic poles;

[0028] at least one target having a substantially cylindrical shape and arranged around the cylindrical support spaced apart from the plurality of magnetic elements, and comprising a material to be deposited on the substrate, the outer side of each magnetic element facing the at least one target;

[0029] - and finally, movement means for relative movement between the tubular support with a plurality of magnetic elements and the target.

[0030] Advantageously, at least one second axis linking the magnetic poles of each magnetic element is transverse and preferably radial to the first axis of the tubular support, the outer side of each magnetic element has the same polarity along its entire extent, and in addition, the polarity of the outer sides of two consecutive magnetic elements on the tubular support alternates along at least the first axis or along at least one direction parallel to the first axis.

[0031] According to one aspect of the invention, each magnetic element has an annular or disc-shaped cross-section with an axis of symmetry substantially parallel to the first axis of the tubular support and a second magnetic orientation axis substantially radial and orthogonal to this first axis of the tubular support.

[0032] Advantageously, the machine according to the invention allows to improve the yield of the sputtering process. More specifically, the presence of magnetic elements and the orientation of the axis linking the poles of each magnetic element relative to the tubular support of the machine allow the plasma ions to be efficiently accelerated towards the target, thus improving the yield of the process.

[0033] Another advantage of the invention consists in the arrangement of movement means for relative movement between the tubular support, which generally incorporates magnetic elements, and the target. The movement means thus allow the etched zone of the target to be monitored and made as uniform as possible.

[0034] According to another aspect of the invention, each magnetic element comprises a plurality of magnets having radial magnetic orientation axes. In other words, each magnetic element, preferably having an annular or disc-shaped cross-sectional shape, comprises a plurality of magnets having the same radial magnetic orientation and closed side by side.

[0035] Advantageously, the geometry of the machine according to the invention can be easily adapted to the desired size, for example depending on the need to deposit material on a substrate of desired size, by simply increasing or decreasing the size of the tubular support and adding or removing magnets between the plurality of magnets constituting each magnetic element. The advantage of easily adapting the size of the machine to different needs allows providing machines for depositing materials of different sizes and geometries by changing as few components as possible, thereby increasing the versatility of the machine structural design and reducing production costs.

[0036] In a preferred embodiment of the invention, each of the magnetic elements is arranged along a helical line on the outer surface of the tubular support so that the outer sides of these magnetic elements have alternating polarity at least in a direction substantially parallel to the first axis along which the tubular support extends.

[0037] According to another aspect of the invention, a machine for depositing material comprises cooling means for cooling at least the target.

[0038] Advantageously, the cooling of the target allows the yield of the process to be increased, since the process does not have to be interrupted in order for the target itself to cool down.

[0039] Furthermore, the energy required to achieve this high deposition rate is dissipated due to the high flow rates of coolant allowed by the present invention as described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Further characteristics and advantages of the present invention will become more apparent from the following description made by way of example with reference to the accompanying drawings, in which:

[0041] - Figure 1 shows a perspective view of a portion of a cathode assembly of a machine for depositing material according to the invention, in a configuration in which the target is not coaxially assembled to the corresponding tubular support of the magnet;

[0042] - Figure 2 A cross-sectional view showing a portion of a cathode assembly of a machine for depositing material according to the present invention

[0043] - Figure 3 A three-dimensional cross-sectional view showing details of a cathode assembly of a machine for depositing material according to the present invention; and

[0044] - Figure 4 shows a representative layout of a cathode assembly of a machine for depositing material according to the present invention;

[0045] - Figure 5 An embodiment of a cathode assembly of a machine for depositing material according to the invention is shown. DETAILED DESCRIPTION

[0046] Summary Reference Figure 1-3 According to the invention, a machine 1 for depositing material on a substrate by means of a cathode magnetron sputtering technique has a basic structure or cathode assembly comprising a tubular support 2 extending substantially along a first axis A and on which, as will be seen, a plurality of magnetic elements 5 are arranged to constitute a static magnetic field, and at least one target 3, preferably of a metallic material, which may have a substantially cylindrical shape and is arranged at intervals around the tubular support 2. The tubular support 2 may further be translated at least relative to the target 3, or vice versa.

[0047] The target 3 is an element of the machine 1 and is made of or comprises a material which, during the sputtering process, is deposited on a substrate to be coated (not shown in the drawings) and is subjected to a potential difference relative to this substrate to be coated.

[0048] More specifically, in Figure 1-3 In the embodiment shown in , the machine 1 is a machine for depositing materials according to cathode magnetron sputtering technology, which includes a cathode assembly placed inside a low-pressure chamber (or a vacuum chamber) and a substrate to be coated, wherein the cathode includes the above-mentioned target 3, and the anode includes the substrate to be coated, and wherein a tubular support 2 is arranged at this target 3 and includes a plurality of magnetic elements 5 capable of defining a suitable static magnetic field.

[0049] The substrate to be coated (on which the material of the target 3 is deposited) is arranged in front of the target 3 itself and spaced apart relative to this target 3 and is also subjected to a potential difference relative to this target 3 (e.g. a few kV), so that the target is the cathode and the substrate to be coated is the corresponding anode.

[0050] As is known, the substrate on which the material is deposited can be one workpiece or a plurality of workpieces arranged side by side during the sputtering process according to the invention. According to a possible embodiment, the substrate can be a tubular piece arranged around the target 3. According to another embodiment, the substrate can be of any geometric shape and have one or more surfaces arranged to be spaced apart relative to the hollow target 3.

[0051] exist Figure 1 It should be observed that the target 3 has been intentionally drawn side by side with respect to the tubular support 2 of the machine 1 , so as to better allow the parts constituting the tubular support 2 to be shown.

[0052] During the cathode sputtering process, the position of the target 3 is Figure 2 and 3 The position shown in , that is, surrounding the tubular support 2 and spaced apart from the tubular support 2.

[0053] In this way, it should be observed that in the figures shown herein, the low-pressure (or vacuum) chamber is not shown, in which the cathode assembly, the support to be surface-coated and the inert gas shown therein are each arranged, and the inert gas, which is in a plasma state and whose ions are accelerated by the magnetic field of the magnetic element 5 arranged on the tubular support 2, allows sputtering of the target 3.

[0054] Between the target 3 and the substrate, in a low-pressure chamber, a volume is obtained suitable for inserting a fluid (e.g. an inert gas, such as argon), which fluid can be ionized due to the ionization activated by the cathode assembly including the target 3. This ionized fluid placed under suitable pressure conditions (e.g. a few tens of mTorr) forms a plasma, which during the sputtering process etches the surface of this target 3 due to the presence of high-energy ions that hit the target 3 itself.

[0055] As mentioned above, the machine 1 for depositing material on a substrate according to the present invention is a machine capable of implementing magnetron sputtering technology and therefore includes magnetic elements 5 on the corresponding tubular support 2, which are capable of generating a static magnetic field in order to increase the deposition rate of the material or the yield of the sputtering process.

[0056] More specifically, in the machine 1 object of the invention, this tubular support 2 develops substantially along a preferably straight axis A and comprises at least one pair of magnetic elements 5 constrained thereto and capable of generating a static magnetic field. The magnetic field generated by the magnets 5 allows the acceleration of the charged ions of the plasma contained between the target 3 and the substrate to be coated.

[0057] The machine 1 also comprises movement means 8 for at least and preferably only for the translational movement of this tubular support 2 relative to the target 3 or vice versa.

[0058] It must be observed that here and in the following, “tubular support 2” refers to a structural component of the machine 1 , composed of one or more parts and having an elongated shape, i.e. having a main dimension relative to the other two axes (i.e. the dimension of axis A), and having the function of supporting magnetic elements 5 responsible for generating a static magnetic field capable of suitably accelerating plasma ions oriented towards the target 3.

[0059] In a preferred embodiment, the tubular support 2 has a generally cylindrical shape, i.e. it is a solid body having its own outer surface, which is obtained by drawing perpendicular lines (called generatrixes) perpendicular to the plane of a given closed line called a directrix (e.g. a circle of a given radius) located on the plane through each individual point on the line (called a generatrix).

[0060] Furthermore, the arrangement of the magnetic elements 5 on this tubular support 2 optimizes the yield of the sputtering process, since the etching of the surface of the target 3 is increased due to the acceleration applied to the plasma ions. Specifically, the ions are accelerated in the direction of the target 3 by means of the Lorentz force, i.e. due to the electromagnetic interaction between the charged plasma ions and the magnetic field generated by these magnetic elements 5.

[0061] The magnetic elements 5 are constrained on the tubular support 2, spaced apart from each other at least along the axis A of the tubular support 2, or generally spaced apart from each other along at least one direction substantially parallel to the axis A. In particular, each magnetic element 5 is spaced apart relative to another magnetic element 5, so that the magnetic field lines determine a substantially arched geometry between a magnetic element 5 and another subsequent adjacent magnetic element 5, due to the fact that, as will be seen, the polarity of the outer sides of two adjacent magnetic elements in the direction of the axis A of the tubular support 2 alternates along this axis A and / or at least in a direction parallel to the axis A.

[0062] The magnetic orientation of each magnetic element 5 is defined by at least one magnetic orientation axis M linking its poles N, S. Furthermore, each magnetic element has two opposite sides, a first inner side preferably constrained to the tubular support 2 and a second outer side protruding from the same tubular support 2 towards the target 3.

[0063] It must be observed that, according to an additional embodiment not shown in the drawings, each magnetic element 5 can be constrained to the tubular support 2 at a point that does not belong to the first of the two opposite sides mentioned above. In other words, the magnetic element 5 can be constrained to the tubular support 2 at a point comprised between the two opposite sides.

[0064] In any case, each magnetic element 5 has an outer side facing the target 3 and an inner side facing the axis A of the tubular support 2 .

[0065] Thus, in the case of a tubular support 2 having a cylindrical geometry, preferably with a circular base (directrix), each magnetic element 5 may for example have a shape of an annular cross section, the axis of symmetry of which passes through the axis A of the tubular support 2 itself.

[0066] Advantageously, according to the present invention, Figure 4 , which depicts a cross section of half of a tubular support 2 with corresponding magnetic elements 5 and a cross section of a corresponding target 3, each magnetic element 5 being constrained to the central core of the tubular support 2 by - in this case but not necessarily - a frame 7, each magnetic element 5 having an outer side (having the same magnetic polarity S or N over its entire extent, i.e. over its entire surface facing the target 3) and an inner side facing the axis A of the tubular support 2 (having opposite magnetic polarity N or S over its entire extent). Moreover, each of such magnetic elements 5 is constrained to the tubular support 2 so that one or more magnetic orientation axes M are always arranged transversely, preferably radially and perpendicularly relative to the axis A of this tubular support 2, and so that the polarity of the outer sides of two consecutive magnetic elements (5) is alternating along the axis A or along at least one direction substantially parallel to this axis A, so as to define a magnetic field in which the magnetic field lines B are located in the above Figure 4 Visible in.

[0067] In particular, as can be seen in the latter figure, the magnetic elements 5 of the machine 1 are arranged on a tubular support 2 , alternating along the axis A of this tubular support 2 with polarity suitably spaced from one another and oriented to the outside thereof.

[0068] In other words, the magnetic elements 5 are arranged on the tubular support 2 so that the sides of the two magnetic elements 5 arranged side by side and in a row facing the target 3 have alternating polarities N and S. For example, if the first magnetic element 5 has a magnetic orientation such that the side facing the target 3 has an N polarity, then the second magnetic element 5 arranged side by side and in a row with the first magnetic element 5 has a magnetic orientation such that the side facing the target 3 has an S polarity.

[0069] exist Figure 4 , the magnetic field generated by the magnetic element 5 is depicted by means of a dotted line of the magnetic field B. The magnetic field lines of the magnetic field B link the poles N, S of the magnetic elements 5 placed side by side. Specifically, the magnetic field lines of the magnetic field B can be curved lines arranged between the magnetic elements 5, more specifically arched.

[0070] The magnetic field lines span the target 3 and affect the region of the machine 1 contained between the target 3 and the deposition substrate, causing the plasma particles contained in said region to be accelerated towards the target 3 .

[0071] It must be observed that, for the sake of simplicity, Figure 4 Magnetic field B lines that might link points of the magnetic element 5 toward the inside of the tubular support 2 are not depicted.

[0072] Turning to the embodiment of the machine 1 described herein, Figure 2 A section through a machine 1 for depositing material is shown, detailing the preferred arrangement of magnetic elements 5 along a tubular support 2 which in this case has a cylindrical geometry with a circular base, according to the geometry assumed by the corresponding target 3 having a cylindrical shape with an annular base.

[0073] Figure 2 The magnetic element 5 of the embodiment shown in FIG. 4 has a substantially cylindrical shape with a circular cross section, the axis of symmetry of which substantially coincides with the axis A of the tubular support 2 .

[0074] Of course, in the machine 1 of the present invention, any other arrangement of the magnetic elements 5 can be used, such as a cylindrical shape or one with an elliptical cross-section or other arrangement, which allows each magnetic element 5 to have a relative outer side with a given magnetic polarity (for example, S) protruding from the tubular support 2 and a relative inner side with an opposite magnetic polarity (for example, N) facing the axis A of the tubular support 2, and makes one or more magnetic orientation axes M of this magnetic element 5 transverse to the axis A of the tubular support 2.

[0075] In either case, where the machine 1 has the cylindrical geometry described herein, in the corresponding cathode assembly, preferably a cylindrical magnetic element 5 is used having an annular cross-section and an axis of symmetry substantially parallel to the axis A of the tubular support 2, each having an outer side or side surface of the same magnetic polarity and an inner side or side surface of the same, opposite magnetic polarity, and having one or more magnetic orientation axes M transverse to the axis A of the tubular support 2.

[0076] Advantageously, in the implementation shown here, the magnetic orientation axis or axes M linking the magnetic poles N, S of each magnetic element 5 are always substantially radial and therefore perpendicular relative to the axis A of the tubular support 2 .

[0077] In fact, the opposite sides of each magnetic element 5 belong to one and the other of the two polarities N, S, respectively, and Figure 2 In the specific embodiment of the present invention, the axis M linking them is arranged so as to be always radial relative to the axis A of the cylindrical tubular support 2, ie always orthogonal to this axis A.

[0078] It must be observed that, obviously, in the case where each magnetic element 5 has a cylindrical shape of annular cross-section and is shaped so that there is only an outer side (cylindrical) of one magnetic polarity and an inner side (also cylindrical) of the opposite polarity, there are infinite or multiple magnetic orientation axes M, which are arranged to form a transverse circle relative to the axis A of the tubular support 2, and in particular, are preferably arranged so as to be radial, i.e. orthogonal, relative to this axis A.

[0079] In addition, preferably, one of the two opposite sides of each magnetic element 5, such as the side with polarity N, can be constrained to the tubular support 2, for example, by the frame 7, and the other outer side of the two opposite sides (such as the side with polarity S) can protrude from the tubular support 2.

[0080] In the implementation of the figures herein, the magnetic elements 5 are appropriately spaced apart from each other on the tubular support 2 along at least one direction parallel to the axis A of the same tubular support 2 , and are preferably arranged to be substantially aligned along an axis parallel to the axis A of the tubular support 2 .

[0081] As described above, the side protruding from the tubular support 2 of each magnetic element 5, the so-called outer side, has polarities N, S in the direction relative to the axis A alternating with the polarities of the side protruding from the tubular support 2 (or the outer side) of the adjacent subsequent magnetic element 5.

[0082] For example, the first magnetic element 5 can have an outer side with a polarity of N protruding from the tubular support 2 (and a corresponding relative inner side with a polarity of S of the same first magnetic element 5), and the second magnetic element 5 adjacent to and located behind the first magnetic element 5 can have an outer side with a polarity of S protruding from the tubular support 2 in a parallel direction relative to the axis A of the tubular support 2 (and a corresponding relative inner side with a polarity of N of the same second magnetic element 5), and so on for all magnetic elements of the multiple magnetic elements 5 of the machine 1.

[0083] In practice, the outer sides of the magnetic elements 5 axially adjacent to each other and consecutive on the tubular support 2 have alternating magnetic poles along a direction defined by the axis A of the same tubular support 2 or along at least one direction substantially parallel to this axis A of the tubular support 2 .

[0084] In the case where the tubular support 2 is of the type having a cylindrical shape, that is, the surface is essentially defined by an infinite number of straight lines (generatrixes) parallel to each other and passing through each point of the closed line (directrix) in a plane perpendicular to the flat closed line, then essentially along each generatrix G of the tubular support 2, the polarity of the outer sides of two adjacent magnetic elements 5 is alternating along the axis A or along at least one direction essentially parallel to this axis A.

[0085] It must be observed that in this case, and if the inner sides of opposite polarity are constrained to the tubular support 2, this tubular support 2 can advantageously be made at least partially of a magnetic or ferromagnetic or even paramagnetic rather than diamagnetic material, in order to close on the tubular support 2 the branch of the magnetic circuit established between adjacent and consecutively placed magnetic elements 5 on the same tubular support 2. As will be seen, in this respect, the tubular support 2 may comprise a frame 7, suitably made of a ferromagnetic material (see also Figure 4 ) and has the function of constraining such magnetic elements 5 to the same tubular support 2.

[0086] Furthermore, according to a particular embodiment of the present invention, the plurality of magnetic elements 5 may have the same distance between opposite sides of each magnetic element 5, i.e., may have equal thickness. In other words, in the case where the cylindrical magnetic element 5 has a substantially circular cross-section, the outer side of each magnetic element 5 surrounds the tubular support 2 at the same distance from the first axis A of the tubular support 2. Or to be more precise, each magnetic element 5 has the same radial length, i.e., the same length in a direction substantially perpendicular to the axis A of the tubular support 2.

[0087] according to Figure 1-3 In the embodiment shown in , each magnetic element 5 may advantageously have a plurality of magnets arranged side by side around the edge of the tubular support 2 , so that the same magnetic polarity N or S is always present along the entire outer side of the corresponding magnetic element 5 .

[0088] In the embodiments shown in the accompanying drawings, as already mentioned, the tubular support 2 can be a substantially cylindrical support, i.e. a type having an outer surface formed by drawing straight lines (generatrixes) through the points of a flat closed line (directrix) parallel to each other and perpendicular to the plane of the closed line, which may be provided with a frame 7, and each magnetic element 5 may have a plurality of magnets arranged in a circle having a center substantially located on the axis A of the tubular support 2.

[0089] In this case, the magnet of each magnetic element 5 can be a substantially rectangular or slightly inclined column or prism, so that the side protruding from the tubular support 2 toward the target 3 extends more than the side constrained to the tubular support 2. The magnetic orientation axis of each magnet constituting each magnetic element 5 has a substantially radial direction relative to the tubular support 2, that is, a direction substantially perpendicular to the axis A of the tubular support 2, so that the magnetic orientation axis M of each magnetic element 5 is always substantially radial, that is, oriented orthogonally to the axis A of the tubular support 2.

[0090] The magnets constituting each individual magnetic element 5 may preferably define an annular cylindrical outside and an annular cylindrical inside, also having opposite polarities.

[0091] The use of multiple magnets to define each magnetic element 5 allows, on the one hand, their rapid replacement if necessary during normal maintenance activities, and on the other hand, the diameter of such magnetic elements 5 can be easily increased or decreased by simply using a frame 7 of increased or decreased diameter and a greater or fewer number of magnets constituting each magnetic element 5.

[0092] It must be observed that, in case the dimensions of the target 3 used are modified, it may be necessary to increase or decrease the diameter of the magnetic element—or its outer dimensions.

[0093] As already mentioned, the tubular support 2 of the machine 1 may also comprise a frame 7 of ferromagnetic or magnetic or even paramagnetic material, which is located inside the magnetic elements 5. In other words, the machine 1 comprises a ferromagnetic frame 7 linking and possibly constraining the magnetic elements 5 to the core of the tubular support 2. According to a possible embodiment, the magnetic elements 5 may in fact be constrained to this ferromagnetic frame 7, in which case it may have a cavity into which each magnetic element 5 may be inserted - and in the case where a respective magnet constitutes each of these elements 5 - and may be integrated to the core of the tubular support 2, for example having a cylindrical columnar shape.

[0094] Such a ferromagnetic frame 7 arranged between the ferromagnetic element 5 and the core of the tubular support 2 allows the magnetic field lines generated by the magnetic element 5 to be accommodated by the closure of the corresponding magnetic circuit, so as to obtain the desired magnetic field.

[0095] It must be observed that the above-described arrangement of magnetic elements 5 having a substantially annular shape (i.e. a cylindrical shape with an annular cross-section) or of disc-shaped such magnetic elements 5 allows in particular to modify the magnetization curve by increasing or decreasing the distance between the axes of the magnets (or between the magnetic elements 5) along the above-mentioned development axis A of the tubular support 2 or along at least one direction substantially parallel to this axis A, so as to optimize the deposition rate of the material and obtain a higher uniformity in terms of the thickness reported on the sample to be deposited.

[0096] For the same purpose, the thickness of the ferromagnetic material of the tubular support 2 can be modified in order to modify the strength of the magnetic field locally, in particular on the last part of the cathode itself.

[0097] Figure 5 An alternative embodiment of the arrangement of the magnetic elements 5 on the tubular support 2 is shown. In this embodiment, the magnets form parallel helices, with the magnetic field orientation being inverted between adjacent helices.

[0098] In particular, according to this possible embodiment, each magnetic element 5A, 5B comprises a plurality of magnets arranged along a helical line around the axis A of the tubular support 2 .

[0099] In practice, the magnetic elements 5A, 5B in this implementation essentially form a double helix spaced apart in a direction substantially parallel to the axis A of the tubular stent 2 .

[0100] The plurality of magnets arranged along the helix form a first helical magnetic element and a second helical magnetic element, which are alternated in the direction of the axis A of the tubular stent 2 or in at least one direction substantially parallel to this axis A of the tubular stent 2. The magnets belonging to the first magnetic element 5a are arranged to have the same polarity on the outside. In the same way, the magnets belonging to the second magnetic element 5b are arranged to have the same polarity on the outside and opposite to the polarity of the magnets belonging to the first magnetic element 5a.

[0101] In this way, the magnets belonging to the magnetic elements 5a, 5b constitute all magnets oriented with the same polarity.

[0102] In addition, also in this embodiment according to the present invention, the magnetic elements 5a, 5b are alternated, and thus the magnets forming the first magnetic element 5a (in other words, the magnets oriented according to the first magnetic orientation) are arranged to be spaced apart from each other along at least one direction substantially parallel to the axis A along which the tubular support 2 develops relative to the magnets forming the second magnetic element 5b (in other words, the magnets oriented according to the second magnetic orientation opposite to the first magnetic orientation).

[0103] In more detail, with reference to this particular embodiment, in the case where the tubular support 2 has a cylindrical shape, the outer sides of the magnets constituting the magnetic elements 5a, 5b spaced apart from each other have alternating polarity in any direction parallel to the axis A of the tubular support 2, i.e., along any generatrix of the cylindrical tubular support 2.

[0104] In fact, by considering any generatrix G of the cylindrical tubular support 2, along the direction defined by this generatrix G, the outer sides of the magnets of two adjacent magnetic elements 5a, 5b have alternating polarities.

[0105] As already mentioned, independently of the embodiment of the magnetic elements described above, the machine 1 may also comprise movement means 8 for relative movement between the tubular support 2 (with the plurality of magnetic elements 5 ) and the target 3 .

[0106] The movement device 8 may allow at least the tubular support 2 and the magnetic element 5 to translate along an axis parallel to or coincident with the axis A of the tubular support 2. In this way, the relative position of the tubular support 2 and the magnet 5 may be adjusted relative to the target 3 and may further allow axially uniform etching of the target 3 itself. The relative movement between the magnetic element 5 and the target 3 may in fact allow the level of etching of the surface of this target 3 to be controlled, thanks to the relative displacement of the static magnetic field (obviously with variable strength in space) defined by the magnetic element 5 relative to the target 3 itself.

[0107] The moving device 8 may be a known moving device, such as, for example, a mechanical, pneumatic or hydraulic moving device.

[0108] The control of the moving device 8 can be manual control, such as, for example, operated by a professional operator, or automatic control, such as, for example, driven by a control unit that is capable of determining parameters useful for the etching uniformity of the target 3 (such as the number of stops and movements of the tubular support 2 with the corresponding magnetic element 5, the translation speed and direction of the tubular support 2 with the magnetic element 5 relative to the target 3).

[0109] In the case where the cathode assembly of the above-described machine 1 provides for the use of a magnetic element 5 having a substantially annular outer side, and the target 3 having a cylindrical geometry, in order to obtain a uniform etching of the target 3 itself, it has proven appropriate that such movement means 8 allow the tubular support 2 with the corresponding magnetic element 5 to be completely translated relative to the target 3, or vice versa.

[0110] According to an embodiment of a moving device 8 combined with the machine 1, in which the magnetic element comprises a plurality of magnets arranged along a spiral line, such a moving device 8 may comprise a device for rotating the tubular support 2 comprising the magnetic elements 5a, 5b, or a device directly for rotating the magnetic elements 5a, 5b relative to the tubular support 2.

[0111] According to another aspect of the invention, the machine 1 may comprise cooling means for cooling components of the machine 1 itself which are heated due to the cathode sputtering process causing the surface of the target 3 to be etched.

[0112] In particular, the machine 1 may comprise a supply system for supplying water or another heat exchange fluid flowing in said tubular support 2 at least through the inlet 9a and the outlet 9b. The water entering the machine 1 is filled at a temperature lower than that of the elements of the machine 1 that need cooling.

[0113] Once the water is introduced through the inlet 9a, it flows through channels that allow the water to come into thermal contact with thermal elements of the machine 1. In this way, heat exchange is possible between a thermal element (such as, for example, the target 3 or an element in thermal contact with the target 3) and an element with a lower temperature (such as, for example, the water introduced into the machine).

[0114] Once the water has passed through the internal conduits of the machine 1 and heat exchange has taken place between the hot body of the machine 1 and the water, the water can be caused to flow through an outlet conduit ending in an outlet 9b for drainage.

[0115] As is sufficient in the machine 1 shown here, it must be observed that in the case where the movement device 8 is of the type of tubular support 2 capable of relative translation only with respect to the target 3 , the hydraulic inflow and outflow circuit of the cooling water is indeed simplified.

[0116] Preferably, by means of the above-described machine 1, the following method can be implemented for depositing a material by cathode magnetron sputtering, the method comprising the following steps:

[0117] a) in a low-pressure chamber (e.g., a pressure of several Pa or tens of mTorr) filled with a preferred inert gas (e.g., argon), a target 3 is pre-arranged at or around a tubular support 2 having a corresponding magnetic element 5, with the target 3 being at an appropriate distance from the tubular support 2;

[0118] b) pre-arranging a substrate to be coated in the low-pressure chamber in front of the outer side surface of the target 3;

[0119] c) establishing a suitable potential difference (e.g. a few kV) between the target 3 and the substrate to be coated, so that a plasma will be formed;

[0120] d) activating a cooling device to cool the target and cathode assembly;

[0121] e) actuating the movement means 8 to translate at least the tubular support 2 relative to the target 3 along an axis parallel to or coinciding with the axis A of the tubular support 2 .

Claims

1. A machine (1) of the type provided with a cathode assembly for depositing material on a substrate by means of a cathode sputtering technique, comprising: a tubular support (2) extending along a first axis (A) of the tubular support (2); a plurality of magnetic elements (5) constrained on the tubular support (2) and spaced apart from each other at least along the first axis or along at least one direction parallel to the first axis, wherein each of the plurality of magnetic elements has at least one second magnetic orientation axis linking corresponding magnetic poles and including an outer side protruding from the tubular support (2) and an inner side facing the first axis of the tubular support (2); at least one target (3) having a cylindrical shape and arranged around the tubular support (2) and spaced apart from the plurality of magnetic elements (5), and the target at least comprising the material to be deposited on the substrate, the outer side of each of the plurality of magnetic elements (5) facing the at least one target (3); A moving device (8) for relative movement between the tubular support (2) having the plurality of magnetic elements (5) and the at least one target (3); Characterized in that the at least one second magnetic orientation axis linking the magnetic poles of each of the plurality of magnetic elements (5) is transverse to the first axis of the tubular support (2), and on the tubular support (2), the polarity of the outer sides of two consecutive magnetic elements is alternating along the first axis or along at least one direction parallel to the first axis; Each of the plurality of magnetic elements (5) comprises a plurality of magnets arranged along a helical line around the first axis of the tubular support (2), and the tubular support (2) is at least partially made of a magnetic or ferromagnetic material.

2. The machine (1) according to claim 1, characterized in that The outer side of each of the plurality of magnetic elements (5) has the same polarity along its entire extent.

3. A machine (1) according to claim 1 or 2, characterized in that Each of the plurality of magnetic elements (5) has an annular or disk-shaped cross-section, whose axis of symmetry is parallel to the first axis of the tubular support (2) and the at least one second magnetic orientation axis is radial and perpendicular to the first axis.

4. A machine (1) according to claim 1 or 2, characterized in that The tubular support (2) has a cylindrical shape, and the machine (1) is characterized in that along each generatrix (G) of the tubular support (2), the polarities of the outer sides of two adjacent magnetic elements (5A, 5B) are alternating.

5. The machine (1) according to claim 1 or 2, characterized in that The outer side of each of the plurality of magnetic elements (5) surrounds the tubular support (2) at the same distance from the first axis of the tubular support (2).

6. The machine (1) according to claim 1 or 2, characterized in that Each of the plurality of magnetic elements (5) comprises a plurality of magnets having radial magnetic orientation axes.

7. A machine (1) according to claim 1 or 2, characterized in that The tubular support (2) comprises a frame (7) of ferromagnetic material facing the inner side of the plurality of magnetic elements (5).

8. The machine (1) according to claim 1 or 2, characterized in that The inner side of each of the plurality of magnetic elements (5) is constrained to the tubular support (2).

9. The machine (1) according to claim 1 or 2, characterized in that The movement device (8) allows at least the tubular support (2) to translate relative to the target (3) along an axis parallel to or coincident with the first axis.

10. The machine (1) according to claim 1 or 2, characterized in that It comprises a cooling device for cooling at least the target body (3).

11. The machine (1) according to claim 10, characterized in that The cooling device comprises supply means for supplying water flowing at least inside the tubular support (2) through an inlet (9a) and an outlet (9b).

12. The machine (1) according to claim 1 or 2, characterized in that The tubular support (2) is a cylindrical support and each of the plurality of magnetic elements (5) has a cylindrical shape with a circular cross section.

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