High-rate magnetron sputtering device

Abstract

The invention relates to the field of vacuum deposition of metal and dielectric coatings, in particular to a device for high-rate magnetron sputtering, and can be used in the manufacture of products with coatings of metals, glass, polymer films and fabric. The device comprises main elements of a magnetron: an anode 1 in the form of an 5 extended perforated tube, a rotating cathode target 2 in the form of an extended pipe, in which a balanced extended magnetic system 3 is tightly seated with a magnetic core 4, and a central 5 and peripheral 6 magnetic poles, a target cooling system with a coolant supply line to the target heating zone and draining it from the cathode cavity. The coolant is supplied to the cooled surface of the magnetron target cathode 2 from the closed cavity 7 0 through a system of holes in the magnetic core 4 into the interpolar space. The coolant at the outlet is sprayed in the form of separate jets formed by holes in the magnetic core 4 and nozzles 11 in the interpolar spacer insert 10. The coolant pressure at the outlet of the holes is 0.4-0.5 MPa, and in the cathode body drops to 0.08-0.12 MPa. Such a flow in the form of high-speed coolant jets promotes effective cooling of the sputtered target in the zone of 5 maximum power density of the plasma discharge, provides favorable conditions for investing high power into the plasma discharge of the magnetron, which significantly increases the rate of sputtering / deposition of coatings compared to a conventional magnetron.

Description

[0001] HIGH-RATE MAGNETRON SPUTTERING DEVICE

[0002] The invention relates to the technique of vacuum deposition of metal and dielectric coatings, in particular to a device for high-rate magnetron sputtering and can be used in the manufacture of products with coatings of metals, glass, polymer films and fabric.

[0003] A common disadvantage of almost all magnetron systems encountered in the industry with a cylindrical rotating target in the form of an extended pipe is an inefficient cooling system, which does not allow creating a high power density of more than 30 W / cm2on the surface in the plasma discharge zone. Such devices have relatively low coating deposition rates (-0.2-0.3 nm / s), since the target is sputtered mainly in a narrow zone, which leads to its local overheating at high applied power. In turn, this leads to thermomechanical bending of the target, and as a result to the failure of the magnetron structure.

[0004] When using targets on a special bonding, so-called bilayer targets, wherein the sputtering target made of brittle or porous material (upper layer) is connected to a mechanically strong base made of heat-conducting material (lower layer), the power density of the plasma discharge is 10-15 W / cm2and, accordingly, the coating rate is lower. The bilayer target has a lower thermal conductivity of the transition boundary, therefore good cooling is very important. The closest to the present invention (the closest prior art) is a device described in the patent RU 2242821 C2 (patent RU 2242821 C2, cl. H01 J 37 / 317, H01 J 37 / 34, C23C 14 / 35, publ. 20.12.2004). The known device comprises a vacuum chamber, an anode, an extended cathode and a magnetic system. The cathode is made in the form of a rotating cylinder, inside which a magnetic system (internal) is fixedly located along its axis. The magnetic system comprises a magnetic core on which three parallel rows of permanent magnets are located. The peripheral rows of magnets are closed at the ends by end magnets and have a polarity opposite to the polarity of the central row of magnets. The sputtering zone is located under the arches of the magnetic field and consists of two straight sections located on the generatrixes of the cylindrical cathode and connected at the ends by rotary sections. With a fixed magnetic field of an arched configuration and a rotating cathode, the entire surface of the cathode passes through the sputtering area and it is consumed along the entire perimeter.

[0005] However, the known device has the same disadvantages: an ineffective cooling system of the surface of cathode target in the zone of maximum heat release; a limitation on the contribution of power to the plasma discharge of the magnetron and, therefore, a low rate of coating deposition on the surface of products.

[0006] The technical problem to be solved by the present invention is to create a device for high-rate magnetron sputtering with an effective cooling system for the surface of the cathode target, enabling the maximum possible contribution of electrical power to the plasma discharge of the magnetron and having a maximum rate of coating deposition with a minimal thermal and mechanical load on the sputtering target.

[0007] To achieve above technical result, in a high-rate magnetron sputtering device, comprising an extended anode in the form of tubes with openings for supplying gases, a body of a sputtering cathode target in the form of a hollow tube with a cooled cavity, inside of which is placed a balanced magnetic system, the body of which is rigidly connected at one end to the base sealing flange and to the coolant supply and drain lines, and at the other end by means of a thrust pin and a thrust bearing is fixed in the end sealing flange, the mentioned magnetic system includes a peripheral magnetic pole and a central magnetic pole interconnected by a magnetic core made of soft magnetic material, and an interpolar spacer insert with outlet holes, over which the sputtering cathode target is installed in a monolithic design, or through a bonding made of metal with high thermal conductivity, and the cooling system of the sputtering cathode-target of the magnetron and the entire body are structurally connected to the magnetic system of the magnetron, according to the present invention, the cooling system of the sputtering cathode target and the entire body of the magnetron is made with the coolant inlet into a closed cavity, above which there is placed the magnetic system with through channels with a diameter of 2.0 to 3.5 mm made in the magnetic core in the gap between the peripheral magnetic pole and the central magnetic pole with a step of 15-20 mm between the centers of the channels for supplying the coolant under pressure from the closed cavity through the outlet holes in the spacer insert to the cooled surface of the sputtering cathode target, to the zone of maximum heat generation, and for carrying the coolant by the rotating target cathode through the gap between the magnetic system and the inner surface of the sputtering cathode target into the inner cavity of the coolant drain to the atmosphere.

[0008] To reduce the height of the gap between the peripheral pole and the central pole of the magnetic system the spacer insert is made of non-magnetic material with the outlet holes in the form of conical nozzles aligned with through channels in the magnetic core for supplying the coolant from the closed cavity into the interpolar space in the form of separate jets through the conical nozzles with a turning angle of 90-120 °.

[0009] The closed cavity for the coolant supply may be aligned with the magnetic core of the magnetic system of the magnetron and may serve not only as an additional cooling element, but also as a supporting console.

[0010] Inside the cooled cavity of the magnetron, to form the coolant flow to the drain with a decrease in pressure and its acceleration, a screen with a fluoroplastic sealant in the form of an insert preventing the flow of the heated coolant from the drain zone to the cooling zone during the rotation of the target cathode can be located.

[0011] Inside the cooled cavity of the magnetron a screen may be installed to separate the coolant drain from the central cavity of the cathode target, between the screen and the inner surface of the cathode-target, the coolant in the inner cavity of the coolant drain is released into the atmosphere with a decrease in pressure, and to prevent a possible overflow of the coolant again into the cooling area in case of overflow of the inner cavity of the coolant drain, a barrier may be provided in the form of an sealing insert made of Teflon.

[0012] The invention is explained in more detail below with reference to the accompanying drawings, wherein is shown:

[0013] In Fig. 1 - a device for high-speed magnetron sputtering with a monolithic cathode target; a view of the magnetic system in the internal cavity of the magnetron cathode target after a longitudinal section of a part of the cathode target;

[0014] In Fig. 2 - a cross-section of the target cathode of the magnetron shown in FIG. 1, along the secant line A-A with a view of the design of the magnetic system and the coolant supply and drain cavities;

[0015] In Fig. 3 - a device for high-speed magnetron sputtering with a cathode target on an intermediate cooled bonding, a view of the magnetic system in the internal cavity of the magnetron cathode target after a longitudinal section of a part of the target cathode;

[0016] In FIG. 4 - a cross-section of the cathode target of the magnetron shown in FIG. 3, along the secant line A-A with a view of the design of the magnetic system and the coolant supply and drain cavities.

[0017] The present invention is illustrated by examples of specific implementation. Example 1.

[0018] A device for high-speed magnetron sputtering with a monolithic cathode target (Fig. 1 and Fig. 2) contains an extended anode 1 in the form of tubes with holes for supplying gases, for example, argon, a body of a magnetron target cathode 2 in the form of a hollow pipe with a base sealing flange 16 and an end sealing flange 15, with a cooled cavity, inside of which is placed an extended balanced magnetic system 3, the body of which at one end is rigidly connected to the base sealing flange 16 and through a cooler inlet 18 is connected to coolant supply lines and through a cooler outlet 19 to cooler drain lines. At the other end, the balanced magnetic system 3 is fixed in the end sealing flange 15 using a thrust pin 13 and a thrust bearing 14. The balanced magnetic system 3 includes a peripheral magnetic pole 6 and a central magnetic pole connected to each other 5 by a magnetic core 4 made of a soft magnetic material, and an interpolar spacer insert 10 with nozzles 11, above which a monolithic sputtered target cathode 2 is installed. The cooling system of the target cathode 2 and the entire housing of the magnetron are structurally connected to the magnetic system 3. The magnetic core 4 has through channels with a diameter of 2.0 to 3.5 mm in the space between the peripheral pole 6 and the central pole 5 with a step of 15-20 mm between the centers of the channels for supplying coolant under pressure from a closed cavity 7. Spacer insert 10 of non-magnetic material is made with conical nozzles 11 aligned with through channels in the magnetic core 4. Between the magnetic system 3 and the inner surface of the target cathode 2 there is a gap that serves for carrying the coolant by the rotating target cathode 2 into the internal cavity of the coolant drain 12 into the atmosphere.

[0019] The device operates as follows.

[0020] Before ignition of the plasma discharge of the magnetron, the rotation drive of the target cathode 2 is switched on (direction of rotation 20) and then coolant-water is supplied under pressure into the target cathode body 2 through input 18 into a closed cavity 7, from which through holes in the magnetic core 4 of the magnetic system 3 in the form of separate jets, with the help of nozzles 11, it is sprayed in the interpolar space between the peripheral pole 6 and the central pole 5 towards the inner surface of the target cathode 2 in the zone of maximum energy release in the form of heat. The holes in the spacer insert 10 with nozzles 11 are aligned with through holes in the magnetic core 4, which are located with an optimal step of 15-20 mm, ensure the overlap of the jets (conventionally shown by arrows around each nozzle 11) along the axis of the interpolar space, and the optimal sweep angle of 90-120° of holes of the nozzles 11 allow the surface to be cooled across the whole width of the interpolar space. After intensive cooling of the surface, the coolant is carried through the gap between the magnetic system (3) and the inner surface of the target cathode 2 by the rotating target cathode 2 into the drain cavity 12. The drain cavity 12 is separated from the central cavity of the magnetron target cathode 2 by a screen 8 and a sealing insert 17 (Fig. .1 and Fig.2) made of fluoroplastic, which prevents the heated coolant from getting back into the cooling zone. From the drain cavity 12, the coolant is removed to the drain through a water outlet connected to the atmosphere. Thus, the coolant in the cooling system of the inner surface of the cathode-target 2 is supplied to the cooling zone at a pressure of 0.4-0.5 MPa (4-5 atm) (the usual inlet pressure of the coolant for cooling targets), and is removed from the cooling zone to the drain cavity 12 with a sharp decrease pressure up to 0.08-0.12 MPa (0.8-1.2) atm. This difference in pressure promotes intensive cooling and intensive removal of coolant from the heating zone.

[0021] To ensure stable operation of mechanisms of the cathode assembly and to prevent coolant leakage from the cathode body, the basic sealing flange 16 is provided at the cooler inlet 18 and cooler outlet 19, rigidly fixed in the body of the target cathode 2 rotation mechanism, and at the end part of the cathode assembly the end sealing flange 15 is installed with a thrust ball bearing 14, on which the thrust pin 13 of the console of the magnetic system 3 of the magnetron is supported to give it mechanical stability during the rotation of the target cathode 2.

[0022] When the plasma discharge of the magnetron ignites and its stable operation begins, the heat generated in the sputtering zone begins to intensively heat the material of the target cathode 2. If it is not cooled, the target material will begin to melt at a certain discharge power. To remove this heat, the target must be intensively cooled. The design of the cooling system described above allows for efficient heat removal from the sputtering zone while investing sufficiently high power into the discharge, 3-5 times higher than with a conventional cooling system in a conventional magnetron. If in an ordinary conventional magnetron it is possible to achieve a discharge power density of 25-30 W / cm2, then with the proposed cooling system, the maximum achievable plasma discharge power density on a monolithic target with its direct cooling is 120-150 W / cm2. Increasing the power density of the plasma discharge significantly increases the rate of deposition of materials and the overall productivity of the process. Testing of the proposed cooling system of the sputtering cathode target was carried out on an experimental vacuum installation for deposition of coatings using a magnetron of the TK-400 type with a monolithic cathode target 2 - a tube made of titanium-niobium alloy of 50:50 composition. The dimensions of the cathode target: diameter 120 mm, length 400 mm (sputtering part is 350 mm long), thickness 8 mm.

[0023] For the inner cavity of the cathode target 2, a magnetic system 3 was designed and manufactured (as shown in Fig. 1 and Fig. 2) with a closed cavity 7 for supplying water to the interpolar space. Low-carbon steel was used as the material of the magnetic core 4, and the peripheral pole 6 and central pole 5 were assembled from permanent magnets SmCos with a size of 20x15x12 mm. In the magnetic core 4 in the interpolar space in the center, were drilled through holes with a diameter of 2 mm with a step of 15 mm between the center of the holes. 6 mm thick fluoroplastic (Teflon PTFE) F-4 plates were used as the spacer insert 10. Through holes with a diameter of 2 mm were also drilled in the plates and then from the outside each hole was drilled with a drill with a diameter of 5 mm to the depth of the drill cone with a sharpening angle of 120° so forming outlet holes 11 in the form of conical nozzles. The drain cavity 12 was formed along the contour of the magnetic system 3 by a screen 8 made of a 1.5 mm thick sheet of 314L stainless steel. The screen 8 was attached to the magnetic core 4 by screws with sealing of the joints with silicone sealant. From the incoming part of the cathode target 2 in the magnetic core 4, a sealing insert 17 was installed in the longitudinal slot in the form of a 4 mm thick plate made of fluoroplastic F-4 with a length equal to the length of the magnetic core 4. From the bottom, the sealing insert 17 was spring-loaded with a soft rubber seal.

[0024] The target was sputtered at an argon pressure of 0.2 Pa in the working chamber. The power density of the plasma discharge was 130 W / cm2at a coolant (distilled water) flow rate of 20 L / s. The water temperature at the inlet into the closed cavity 7 was 18 °C and at the outlet from the drain cavity 12 was 25 °C. The water pressure at the inlet into the closed cavity 7 was 0.4-0.5 MPa and at the outlet from the drain cavity 12 was 08-0.12 MPa. The magnetron worked stably and there was no visual heating of the cathode target 2, and the temperature of the water did not exceed the room temperature.

[0025] When using a high thermal conductivity target material, such as copper, the discharge power density can be raised to 250-350 W / cm2

[0026] Example 2 A high-speed magnetron sputtering device with a target cathode on an intermediate cooled bonding (Fig. 3 and Fig. 4) is made and operates similarly as described in Example 1. The difference is that the cathode-target 2 made from a material with a relatively low thermal conductivity is installed on a bonding 9 made from a metal with high thermal conductivity. The bonding 9 improves cooling of the cathode-target 3 during its spraying.

[0027] Testing of the proposed cooling system of the sputtering cathode target was carried out on an experimental vacuum installation using a TK-400 type magnetron with a two- layer structure, where a cathode-target 2 made of a 3 mm thick layer of chromium deposited by a galvanic method is placed on a copper bonding 9 made of an oxygen-free copper pipe with a diameter of 110 mm, a length of 400 mm and a thickness of 5 mm.

[0028] Chromium is a brittle material and therefore for its use as a target, various technologies for its application to metal bonds are used: deposition from the gas phase (CVD technology); plasma-arc deposition from powder in a controlled atmosphere; pressing powder with sintering and galvanic deposition from solutions. The latter method is most suitable when using bonding in the form of a copper pipe. The previous three methods are high-temperature and stainless steel bonding is applicable for their use.

[0029] For the inner cavity of the cathode target 2, a magnetic system 3 was designed and manufactured (as shown in Fig. 1 and Fig. 2) with a closed cavity 7 for supplying water to the interpolar space. Low-carbon steel was used as the material of the magnetic core 4, and the peripheral pole 6 and the central pole 5 were assembled from permanent magnets SmCos with a size of 20x15x12 mm. In the magnetic core 4 in the interpolar space in the center, were drilled through holes with a diameter of 2 mm with a step of 15 mm between the center of the holes. 6 mm thick fluoroplastic (Teflon PTFE) F-4 plates were used as the spacer insert 10. Through holes with a diameter of 2 mm were also drilled in the plates and then from the outside each hole was drilled with a drill with a diameter of 5 mm to the depth of the drill cone with a sharpening angle of 120°. The drain cavity 12 was formed along the contour of the magnetic system 3 by a screen 8 made of a 1.5 mm thick sheet of 314L stainless steel. The screen 8 was attached to the magnetic core 4 by screws with sealing of the joints with silicone sealant. From the incoming part of the cathode target 2 in the magnetic core 4, a sealing insert 17 was installed in the longitudinal slot in the form of a 4 mm thick plate made of fluoroplastic F-4 with a length equal to the length of the magnetic core 4. From the bottom, the sealing insert 17 was spring-loaded with a soft rubber seal. The target was sputtered at an argon pressure of 0.2 Pa in the working chamber. The power density of the plasma discharge was 95 W / cm2at a coolant (distilled water) flow rate of 20 L / s. The water temperature at the inlet into the closed cavity 7 was 18 °C and at the outlet from the drain cavity 12 was 20 °C. The water pressure at the inlet into the closed cavity 7 was 0.4-0.5 MPa and at the outlet from the drain cavity 12 was 08-0.12 MPa.

[0030] Such sputtering mode is associated with the low thermal conductivity of galvanic chromium. The magnetron operated in a stable manner, and no heating of the target surface in the sputtering zone was observed. When the target was rotated, its surface remained dark.

Claims

CLAIMS1. A high-rate magnetron sputtering device, comprising an extended anode (1) in the form of tubes with holes for supplying gases, a body of a sputtering cathode target (2) in the form of hollow tube with a base sealing flange (16), an end sealing flange (15) and a cooled cavity, inside of which is placed an extended balanced magnetic system (3), the body of which is rigidly connected at one end to the base sealing flange (16) and to the coolant supply and drain lines, and at the other end by means of a thrust pin (13) and a thrust bearing (14) is fixed in the end sealing flange (15), the mentioned magnetic system (3) includes a peripheral magnetic pole (6) and a central magnetic pole (5) interconnected by a magnetic core (4) made of a soft magnetic material, and an interpolar spacer insert (10) with outlet holes, over which the sputtering cathode target (2) is installed in a monolithic design, or through a bonding (9) made of metal with a high thermal conductivity, and a cooling system of the sputtering cathode target (2) of the magnetron and the entire body are structurally connected to the magnetic system (3) of the magnetron, characterized in that the cooling system of the sputtering cathode target (2) and the entire body of the magnetron is made with the coolant inlet into a closed cavity (7), above which there is placed the magnetic system (3) with through channels with a diameter of 2.0 to 3.5 mm made in the magnetic core (4) in the space between the peripheral magnetic pole (6) and the central magnetic pole (5) with a step of 15-20 mm between the centers of the channels for supplying the coolant under pressure from the closed cavity (7) through outlet holes (11) in the spacer insert (10) to the cooled surface of the sputtering cathode target (2), to the zone of maximum heat generation, and for carrying the coolant by the rotating cathode target through the gap between the magnetic system (3) and the inner surface of the sputtering cathode target (2) into the inner cavity of a coolant drain (12) to the atmosphere.

2. The device according to claim 1, characterized in that the spacer insert (10) is made of non-magnetic material with the outlet holes (11) in the form of conical nozzles aligned with through channels in the magnetic core (4) for supplying the coolant from the closed cavity (7) into the interpolar space in the form of separate jets through the conical nozzles (11) with a turning angle of 90-120°.

3. The device according to claim 1, characterized in that the closed cavity (7) for the coolant supply is aligned with the magnetic core (4) of the magnetic system (3) of the magnetron.

4. The device according to claim 1, characterized in that inside the cooled cavity of the magnetron a screen (8) is installed to separate the coolant drain (12) from the central cavity of the cathode target, between the screen (8) and the inner surface of the cathodetarget (2), the coolant in the inner cavity of the coolant drain (12) is released into the atmosphere with a decrease in pressure, and to prevent a possible overflow of the coolant again into the cooling area in case of overflow of the inner cavity of the coolant drain (12), a barrier is provided in the form of an sealing insert (17) made of Teflon.

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