Spattering Device for Its Embodiment

The invention refers to the methods of production of the nanomaterial in vacuum and magnetron sputtering devices for their embodiment, which can be used in the nanotechnology to obtain nanomaterials with improved physical properties including highly selective catalysts, synthesized nanoparticles and monodispersed powders.

It is known that nanostructures the surface density of particles of which is 10 ¹² cm ² are promising for the creation of highly efficient na noelectron ic devices, such as ultrafast switches, ultracompact memory cells, etc. The efficient use of nanostructured materials in these areas depends significantly on the surface density of nanoparticles, which in turn depends on dispersion size and value.

Essentially, the difference between the nanostructured materials and bulk materials is that the number of their surface atoms is comparable to the number of atoms in the volume, and the surface curvature radius is comparable to the constant of the crystalline lattice. At that the electrons can be exchanged not only between surface atoms, but also between substrate atoms, which ensures the high catalytic activity of monolayer nanostructured coatings. For a number of important practical applications, the most promising is the production of highly-efficient catalysts based on the nanostructured materials of metals of platinum group, for example, for electrodes of hydrogen thermal elements.

The known methods for production of nanomaterials can be divided into two main groups according to the physics of processes: by the synthesis of atoms, clusters, complex radicals, molecules, and by dispersion of bulk materials. From the first group of the above methods both physical (thermal evaporation and condensation, ion sputtering) and chemical (e.g. gas-phase chemical reactions, water-heating reactions, sol-gel, etc.) methods are widely used. However, chemical methods have some limitations. Despite the fact that the cost of products obtained by these methods is low, they cannot ensure production of pure high-quality nanomaterials without the admixture of reagents. The sol-gel method also provides for the low cost of production, but the nanoproducts obtained by this method are polluted by reagents.

The thermal plasma is mainly used in the physical methods and they can be characterized as intensive ones. These methods use powerful plasma flows, electric arc discharges, laser and electron-beam plasma, plasma of high-frequency induction discharge, etc. These methods can be used to produce high quality monodispersed nanomaterials with densely packed structure; however, the wide application of these methods is significantly restricted due to the coagulation of particles on the substrate in the process of their synthesis.

In modern technologies of synthesis of nanomaterials the electrodispersion of liquid droplets is widely used, which is based on the phenomenon of emergence of the Rayleigh (capillary) instability of a droplet of R size relative to the process of decay when the value of its charge reaches the critical value: Q _cr =8n(£oaR ³ ) ^1/2 , where a is the surface tension coefficient (see A. I. Grigoriev, S. 0. Shiryaeva, Regularities of Rayleigh Decay of the Charged Droplet, Journal of Technical Physics (JTP), 1991, vol. 61, Issue 3, p. 19).

It is noteworthy that daughter droplets are initially unstable, and the decay process is cascading and stops at a certain stage (d _mi n~8-10 ⁷ £a ³ ) when a particle loses its charge as a result of field emission. For most materials, these sizes make a few nanometers (nm) and have a fairly narrow strip of distribution by sizes. That is why the electrodispersion method is very promising for production of highly dispersed nanomaterials. In the plasma, metal droplets are charged to a critical value and their decay starts. In the plasma, microparticles and in particular, droplets acquire negative charge as a result of collision with electrons. The value of this charge is determined by the value of floating potential and depends on plasma parameters. The system and method of production of nanoparticles in a plasma microreactor at atmospheric pressure are known which are described in the patent document [1]. In application of these system and method, the limitation of residence time of nanoparticles, their growth and coagulation in the zone of nucleation are achieved through using the thermal plasma microdischarges.

The system described in this document contains the first cathode, which includes the first metal tube connected to the first end and the second end, the first anode, which includes the second metal tube connected to the third end and the fourth end; and the first container, which includes the first gas input. The first end and third end are located in the inner part of the first container. The first end and the third end are separated by the first interval and the first metal tube is designed with the option of carrying the first gas from the second end to the first end, and the first container is designed with the option of carrying the second gas from the first input to the second metal tube from the second end to the first end through at least the first part of the first interval.

The method of production of nanoparticles presented in the document [1] provides for the creation of a plasma reactor which contains the cathode connected to the first end and the second end, the anode connected to the third end and the fourth end and a container; at that the first end and the third end are separated by an interval and are located inside the container; the gas flow is supplied from the second end to the first end; the initiation of the plasma discharge at the first pressure value, which is equal to or higher than the atmospheric pressure; the maintenance of the plasma discharge at the second pressure value, which is equal to or higher than the atmospheric pressure; at that the maintenance of the plasma discharge provides for the formation of the multiplicity of nanoparticles.

Some variants of this method involve the use of high-density plasma microdischarges for the synthesis of silicon nanoparticles. In this case, the microreactor at the atmospheric pressure is used as a reactor, in the reaction zone of which the residence time of nanoparticles is limited. The residence time of particles in the nucleation zone is limited to milliseconds, which allows for the production of ultrapure particles with a narrow distribution by sizes. When using the mixture (Ar + SiH ₄ ) in kind of the first gas flow, it is possible to synthesize silicon nanoparticles which size does not exceed 2 nm. These particles can be collected on a substrate in a receiving container, or in liquid immediately after synthesis.

The disadvantage of the device and method described in the patent document [1] is the low productivity due to a very low value (milliamperes) of discharge current between the electrodes while the small particle flow rate and low productivity complicates the industrial use of this method.

There is also a known method of production of nanoparticles described in the patent document [2], which includes dispersion of the material through applying to the pointed cathode made of a conductive material with a radius of curvature of the point of no more than 10 pm, the electric field which intensity at the cathode point is at least 10 ⁷ V/cm, supply of the obtained liquid droplets of this material to the electric discharge plasma. At that, the electric discharge pulse duration is not less than 10 ps and it is created in the inert gas medium at the pressure IO q ¹ Pa in the conditions of application of the difference of potentials of at least 2 kV between the electrodes and the simultaneous assistance of the magnetic field with the intensity of at least 600 Gs perpendicular to the plasma creating electric field. The cooling of liquid nanoparticles produced in plasma in an inert gas medium before their curing and coating of the produced cured nanoparticles on the substrate are provided. The parameters of the created plasma meet the requirements of pre-determ ined ratios. Unlike other known methods in which droplets are charged in a laser plasma flare, according to this method, the nanoparticles are produced not as a result of their synthesis from the gas phase, but as a result of cascading decay of macrodroplets in the plasma with certain parameters under the conditions of development of the Rayleigh or capillary instability process. The liquid nanoparticles produced as a result of the decay cure after leaving the plasma region and condense on the substrate.

For effective transformation of metals into nanostructured state by the method described in the patent document [2], the compatibility of the vacuum chambers for plasma formation and metal droplets formation is required. In this context, many known methods of material dispersion may become inconsistent, which may impose certain restrictions on the choice of initial materials. For example, there can be certain difficulties in process of working with refractory metals.

The known method of production of nanoparticles according to the document [3], provides for the dispersion of the molten material and supply of liquid microdroplets of this material into the electron flux to recharge the microdroplets to the state where their cascading decay and production of nanoparticles on the substrate begin. In order to recharge the microdroplets to the state in which their cascading decay begins, the electron flux parameters and the residence time of microdroplets in it are selected from the following ratios:

Where ris the radius of charged liquid droplets (m),

E— the mean electron energy (joule), n - the electron flux density (m ³ ),

T- the droplet charging time (sec), a- the surface tension coefficient of the melt (newton/m), e - the electron charge (coulomb), eo- the dielectric constant (farad/m), m _e - the electron mass (kg).

The disadvantage of the method of production of nanoparticles described in the document [3] is its low efficiency due to the fact that in the process of electrodynamic dispersion the formed microdroplets of molten material are accelerated in a strong electric field and obtain a rather high speed of movement (more than 100 m/s), and the number of their recharging acts does not exceed several units. As a result, in addition to the production of nanoparticles of several nm in size, larger particles are produced.

The device described in the document [3] for embodiment the above method consists of three units: the microdroplet flow formation unit, the microdroplet recharging unit and the nanoparticle coating unit. The microdroplet flow formation unit contains a needle metal anode metal and the microdroplet recharging unit contains a metal housing of hollow-cylinder shape with central frontal holes (with zero potential), which provides the exit of the electron flux and the passage of generated nanoparticles. The nanoparticle coating unit contains a substrate. The electron emitter installed on the housing is made in kind of tungsten spirals connected to the source of current.

The disadvantage of the device described in the document [3] is that it does not provide effective recharging of dispersed microdroplets of the melt material because of short time of their residence in the microdroplet recharging unit, which leads to a significant diversity of the sizes of the produced nanoparticles. In addition, the disadvantage of the described device is the necessity to use the expensive production equipment, low efficiency and productivity, which limits its wide industrial application. The most close to the presented invention from the technical aspect is the planar magnetron sputtering device described in the patent document [4], which contains a vacuum chamber where an anode, a cathode with a disk target and a cathode assembly containing a magnetic system and a cathode assembly coolant system are placed. The magnetic system in the cathode assembly is fixed on the disk made of soft magnetic material which is fixed on the disk carrier with blades, which is designed with the option of rotation with the assistance of a coolant jet. The magnetic system contains groups of permanent magnets placed on the disk. The like poles of each group are located along the loop made of the involutes of the circumference of a circle of specific radius. In addition, one of the groups of magnets is located outside the said loop, and the second group of magnets is located inside the said loop. Opposite the poles of magnets of one of the groups located along this loop there are placed the poles of the relevant magnets of the second group with opposite polarity. At that the magnet groups create a closed loop. The cathode assembly of the device contains a mechanism regulating the magnetic system rotation speed. The device is designed with the option of working both in the conditions of rotation of the magnetic system, and in the stationary mode. The magnetic system is designed with the option of regulating the distance between the magnets in the range of 3-10 mm. The rotation speed regulating mechanism is connected to the software control device.

The disadvantage of the device described in the document [4] is that it does not allow to obtain satisfactory results, namely, the design of the cathode assembly of the device and the mechanism of magnetic system rotation speed control placed in the cathode assembly, does not allow to effectively control the number of magnetic system revolutions in the conditions of the magnetic system rotation.

The technical result of the presented invention is the increase of reliability, productivity and quality of control of the device, simplification of technological process, improvement of frequency of occurrence and physical properties of the obtained nanoparticles. In addition, the use of this invention provides the possibility of coating films of nanoparticles on an area of more than 100 cm ² , which in the entirety facilitates solution of the problems associated with commercialization.

The invention presents two objects: the method of production of nanomaterial in vacuum and magnetron sputtering device for production of nanomaterial in vacuum.

The essence of the invention, which provides the achievement of technical result and avoids the disadvantages of its analogues, is that one of the objects presented by the invention, the method of production of nanomaterial in vacuum is embodied with the magnetron sputtering device. Over the disk target in the vacuum chamber of this device, coaxially to the disk target there is located a magnetic system that forms a magnetic field with a loop configuration, consisted of the involutes of the circumference of a circle of specific radius. The magnetic system contains relevant groups of permanent magnets and is designed with the option of automatic regulation of speed of rotation and regulation of the distance between its poles. In addition, this method provides for the performance of the following technological operations:

Through rotating the magnetic system in the parallel surface towards the disk target surface, formation of a rotating magnetic field with a closed loop configuration, containing the involutes line, the rotation axis of which passes through the center of the target; formation of an active zone of sputtering between the inputs and outputs of the magnetic field power lines created on the disk target surface by applying the electric field and rotating magnetic field to the disk target surface; formation of a gas discharge on the disk target surface in the form of a closed loop, consisting of the involutes of the circumference of a circle of specific radius, and magnetron plasma of the shape of a torus over the active region of sputtering by manipulating the values of working gas pressure in the vacuum chamber and the power applied to the disk target; formation and dispersion of cathode spots through ionization of working gas atoms in the said toroidal magnetron plasma and their acceleration in dark cathode region of glow discharge plasma in close proximity to the disk target surface; cascading decay of produced liquid macrodroplets of material of the disk target in the magnetron plasma of the shape of a torus and curing of nanoparticles created as a result of such decay.

In addition to the above operations, this method of production of nanomaterial in vacuum includes the creation of a reactor for formation of nanoparticles, which in the process of sputtering of the disk target material additionally provides for:

The compact accommodation of the zones forming a closed loop configuration of the flow of macrodroplets in the active zone of sputtering and the cascading decay of the toroidal plasma; continuous movement of the forming reactor along the disk target surface with regulation of the distance between the inputs and outputs of magnetic field power lines on this surface and automatic control of the speed of revolutions of the rotating magnetic field with its current values and specific current parameters characterizing the processes created in the reactor; at the same time, the formation and dispersion of the above cathode spots additionally provides for the bombarding of the disk target with the working gas ions, supply of the said flow of macrodroplets of the liquid disk target material created as a result of the formation and dispersion of cathode spots in the toroidal magnetron plasma; the cascading decay of the formed liquid material of the disk target additionally provides for carrying out of this decay process in the conditions of recharging of liquid macrodroplets in the toroidal magnetron plasma and development of Rayleigh or capillary instability process, and carrying out the process of cooling and curing of nanoparticles formed as a result of cascading decay - in the outside region of the toroidal plasma.

According to one variant of embodiment of this method, the technological process of formation and dispersion of cathode spots additionally provides for the sputtering of not sputtered regions of the disk target by their bombardment with working gas ions creating an active region of sputtering through the alternating wave-like movement of ion flux, which affects non sputtered regions with the maximum intensity, symmetrically decreasing in both directions, and the automatic control of the speed of rotation of the magnetic field.

Another variant of embodiment of this method provides for the production of nanomaterial in the form of synthesized nanoparticles on the substrate, which additionally provides for the synthesis of cured nanoparticles on the surface of the substrates mounted on a planar or planetary substrate carrier, located in the working zone of the magnetron sputtering device towards the disk target and at a certain distance from it.

One more variant of embodiment of the method, which ensures for the production of nanomaterial in the form of nanoparticles, additionally provides for the continuous movement of the magnetron toroidal plasma region under the effect of a rotating magnetic field on the surface of the disk target. The curing of nanoparticles resulting from the cascading decay additionally provides for the beginning of the curing process after the output of the nanoparticles outside the toroidal plasma region between the surface of the disk target and the planar or planetary substrate carrier located in the vacuum space; the provision of diffusive, random and thermal movement of the produced nanoparticles and their free fall along a spiral trajectory in the vacuum space between the surface of the disk target and the planar or planetary substrate carrier and final cooling and curing of the produced nanoparticles.

One of the variants of the embodiment of the method provides for production of the nanomaterial in the form of cured monodispersed nanopowder and envisages its separation by means of a separation unit located in the working zone of the magnetron sputtering device, and the supply of powder to the receiving container installed at the output of the device. One more variant of embodiment of the method which ensures the production of a nanomaterial in the form of the cured monodispersed nanopowder, additionally provides for: continuous movement of the toroidal magnetron plasma region on the surface of the disk target assisted by the rotating magnetic field; curing of nanoparticles produced as a result of cascading decay additionally provides for the beginning of the curing process after the nanoparticles leave the toroidal plasma region to the vacuum space between the disk target surface and the nanopowder receiving container; ensuring diffusive, random or thermal movement of the produced mixed nanoparticles and their free fall along the spiral trajectory in the vacuum space between the disk target surface and the nanopowder receiving container and final cooling and curing of the produced nanopowder.

Another variant of embodiment of the method provides production of the nanomaterial on the substrate in the form the film of coagulated particles and spherical nanoparticles scattered in the volume or quantum dots in kind of the film, which additionally provides for the placement of the planar or planetary substrate carrier at such a distance from the disk target surface that ensures the maintenance on the substrate of the temperature level of nanoparticles produced as a result of cascading decay and creation of the conditions for formation of the isolated quantum dots in the volume of the film of the sputtered material of the disk target.

One more variant of embodiment of the method ensures the production on the substrate of nanomaterial consisting of individual spherical nanoparticles with an amorphous structure in the form of a film, which additionally provides for the placement of a planar or planetary substrate carrier at such a distance from the disk target surface that ensures the maintenance of the temperature level of nanoparticles produced as a result of cascading decay on the substrate and the performance of the conditions for emergence of Van der Waals bonding or metal bonding. The second object of the invention, the magnetron sputtering device for production of nanomaterial in vacuum, contains a vacuum chamber in which an anode, disk target made of non-magnetic material, cathode assembly and liquid cooling system of cathode assembly are placed; the cathode assembly has the shape of a hollow cylinder, in its inner part there is a disk target carrier with a disk target, a magnetic system with a disk made of soft magnetic material, on which groups of permanent magnets are placed; the disk made of soft magnetic material is fixed on the disk carrier equipped with blades, which has the shape of a hollow cylinder and is made with the possibility to rotate under the cathode assembly coolant jet assisting these blades; the permanent magnets with like poles of each group are located along the corresponding closed loop composed of the involutes of the circumference of a circle of specific radius, at that the magnets of one of the groups are located outside the loop and the magnets of the second group are inside the loop; opposite the poles of magnets of one of the groups placed along the closed loop, there are located the poles of magnets of the second group with opposite polarity; the magnetic system is designed with the option of work both in stationary and rotation modes, as well as with the option of regulating the distance between adjacent magnets with opposite polarity.

In addition to the above, this magnetron sputtering device additionally contains a disk target lock made of non-magnetic material and the magnetic system rotation rate control unit, which is installed above the magnetic system in the inner part of the cathode assembly and connected to the software control device.

At that, the disk target installed on the disk target carrier and fixed by the disk target lock, the cathode assembly with this disk target carrier located in it, the magnetic system, the magnetic system rotation rate control unit and the liquid cooling system of the cathode assembly form a sequence of these assemblies and elements, arranged coaxially to each other in a vertical direction bottom-up, which is placed over the processed products placed in the working zone of the vacuum chamber and/or other objects necessary for the technological process; the magnetic system rotation rate control unit includes the dielectric housing with the shape of the hollow cylinder with the central end aperture, motionlessly fixed in the internal part of the disk carrier, on the internal surface of which at certain levels there are installed permanent magnets and a brake ring, accordingly; the fixed disk made of dielectric material and attached to the cathode assembly, on which there is installed a magnetic sensor with a possibility of interaction with the magnets placed in this housing, and piezoelectric elements located with the possibility of establishing mechanical contact in the process of work that causes friction with the brake ring; the terminals of the sensor and piezoelectric elements are connected to the software control unit.

According to one of the variants of embodiment of the method, the magnetron sputtering device is adapted to produce a nanomaterial in vacuum in the form of nanoparticles and additionally contains a planar substrate carrier located in the working zone of the vacuum chamber; at that the sequence of these assemblies and elements is located above the said planar carrier in such a way that the surfaces of the substrates fixed on it are directed towards the disk target and located from it in a certain distance to ensure the synthesis of produced nanoparticles on the substrate surfaces.

According to another variant of embodiment of the method, the magnetron sputtering device is also adapted for production of nanomaterial in a vacuum in the form of nanoparticles and additionally contains a stainless steel cylindrical housing, in which a planetary substrate carrier is located coaxially; the housing is coaxially connected to the vacuum chamber forming a single vacuum space with it; at that the sequence of these assemblies and elements of the device is located above the planetary carrier in such a way that the concave surface of the carrier and the surfaces of the substrates fixed on it are directed towards the disk target and are separated from it by a certain distance to ensure the synthesis of produced nanoparticles on the substrate surfaces.

According to one more variant of embodiment of the method, the magnetron sputtering device is adapted for producing nanomaterial in vacuum in the form of monodispersed powder and additionally contains: a funnel-shaped hopper installed in the working zone of the vacuum chamber and equipped with a separating device, and receiving container for the produced powder installed at the output of the hopper; the separating device is made in the form of a spherical segment element attached at a certain height to the inner surface of the funnel-shaped hopper, coaxially to this hopper and with its convex surface it is directed towards the receiving part of the hopper; the sequence of these assemblies and elements of the device is located above the receiving part of the funnel-shaped hopper, and between the walls of the separating device and the inner surface of the hopper there is a gap of a certain width to ensure the passage of the produced powder to the separating unit and receiving container.

The invention is represented by four figures: Figure 1 shows the schematic representation of the proposed variant of embodiment of the magnetron sputtering device designed to produce nanoparticles in a vacuum using a planar substrate carrier; Figure 2 shows one of the variants of the magnetic system designed in accordance with the loop of the involutes of the circumference of the circle of a specific radius; Figure 3 shows the schematic representation of the proposed variant of embodiment of the magnetron sputtering device designed to produce nanoparticles in a vacuum using a planetary substrate carrier; Figure 4 shows the variant of the embodiment of the magnetron sputtering device designed to produce a monodispersed powder in a vacuum.

The magnetron sputtering device for production of nanomaterial in vacuum (see Figures 1, 3 and 4) contains vacuum chamber 1, anode 2, cathode assembly 3, cathode assembly coolant system 4, disk target 5 made of non-magnetic material, disk target carrier 6, disk 7 made of soft magnetic material, group of permanent magnets 8, blades 9 of cathode assembly cooling system, disk carrier 10 with the shape of hollow cylinder, disk target lock 14, magnetic system rotation rate control unit 15, housing 16 having the shape of hollow cylinder, permanent magnets 17, brake ring 18, fixed disk made of dielectric material 19, magnetic sensor 20, piezoelectric elements 21, terminals of piezoelectric elements 22, program control device 23, planar substrate carrier 24, substrate 25, working gas supply system 26 (as shown in Figure 1); cylindrical housing made of stainless material 29, planetary substrate carrier 30 (as shown in Figure 3); funnel-shaped hopper 31, separating device 32 and powder receiving container 33 (as shown in Figure 4).

Above the objects placed in the working zone of vacuum chamber 1 (the products to be processed, e.g. substrates) and/or auxiliary devices (e.g. substrate carrier or separating device), there is arranged coaxially to each other a set of the following assemblies and elements in sequence vertically from bottom to top: anode 2, disk target 5 installed in the disk target carrier 6 and fixed with the disk target lock 14 made of non-magnetic material, groups of permanent magnets 8 of magnetic system, disk 7 made of soft magnetic material, magnetic system rotation rate control unit 15, as well as liquid cooling system 4 of the said cathode assembly 3.

The cathode assembly 3 has the shape of a hollow cylinder and contains a disk target 5, fixed with a disk target lock 14, and in the inner part of the cathode assembly there is a disk target carrier 6 with a disk target 5 placed in it, a magnetic system consisting of a disk 7 made of soft magnetic material and groups of permanent magnets 8 mounted on it. The disc 7 is fixed on the disc carrier 10 which has the shape of a hollow cylinder with blades 9 and is made with the possibility of rotation under the influence of a coolant jet in the liquid cooling system 4 of the cathode assembly .

The disc target lock 14 is a wedge-shaped ring made of non-magnetic material (e.g., stainless steel) consisting of two semi-rings, which are mounted and fastened in a circular slot between disc target 5 and its carrier 6, which also has a wedge-shaped profile. The disc target lock 14 provides a highly reliable mechanical, thermal and electrical contact between the disc target carrier 6 and the disc target 5 placed in it, which is necessary in case the high power is applied to the magnetron sputtering device. In addition, the magnetron sputtering device, in which the disc target lock 14 is used, can be installed in any part (top, bottom, sides) of the inner space of the vacuum chamber and in a plane with any angle of inclination, which will contribute to the expansion of its functionality.

The like poles of each group of permanent magnets 8 are located along loops 12 and 13 (see Figure 2), composed of the involutes 11 of the circumference of a circle of specific radius. The magnets of one of the groups are located outside of loop 12, creating one of the poles of the magnetic system (e.g. pole N), and the magnets of the other group are located inside loop 13, creating another pole of the magnetic system (e.g. pole S).

The magnetic system is equipped with the above-mentioned rotation rate control unit 15, which is connected to the program control unit 23 (see Figures 1, 3 and 4), and is designed to work both in the stationary position and in rotation mode. In addition, the magnetic system has the option of regulation of the distance (in the range of 3- 10 mm or another interval) between the adjacent magnets with opposite polarity of the groups of magnets 8.

The magnetic system rotation rate control unit 15 contains the disk carrier 10 having the shape of a hollow cylinder with blades 9 and inside it the motionlessly fixed housing 16 made of dielectric material with the central end apertures, on the inner surface of which at certain levels there are mounted permanent magnets 17 and brake ring 18 made of a dielectric frictional material.

The rate control unit 15 also contains a fixed disk 19 made of dielectric material and attached to the cathode assembly 3, on which in the said housing 16 there is fixed a magnetic sensor 20 having the option to interact with the magnets 17 mounted, and the piezoelectric elements 21, between the respective surfaces of which and the working surface of the brake ring 18, installed in the housing 16, in the course of the work process the mechanical contact generates causing friction. Electrical terminals 22 of the magnetic sensor 20 and piezoelectric elements 21 are connected to the program control unit output 23.

Figure 1 shows one of the variants of embodiment of the magnetron sputtering device with the option of producing nanoparticles in a vacuum and the synthesis of the produced nanoparticles on the substrate, which contains a planar substrate carrier 24, installed in the working zone of the vacuum chamber 1, on which the substrate 25 is fixed so that the disk target 5 is located above the planar substrate carrier 24, i.e. the surface of the substrate 25 fixed on the planar substrate carrier 24 is directed towards the disk target 5 and is a certain distance away from it.

Figure 3 shows the second variant of the magnetron sputtering device, design with the option of producing nanoparticles in a vacuum and the synthesis of the produced nanoparticles on the substrate, which contains a cylindrical housing 29 made of stainless steel, installed in the working zone of vacuum chamber 1 with a planetary substrate carrier 30, on which substrates 25 are fixed. The concave surface of the planetary substrate carrier 30 is directed towards the disk target 5 and is a certain distance away from it.

Figure 4 shows one more variant of the magnetron sputtering device designed for production of monodispersed powder in vacuum, which additionally contains a funnel- shaped hopper 31 equipped with a separating device 32, which is installed in the working zone of vacuum chamber 1, and powder receiving container 33 installed at the output. The separation device 32 is made in kind of a spherical segment element which is attached at a certain height to the inner surface of funnel-shaped hopper 31, coaxially to this hopper and by its convex surface is directed towards the receiving part of the hopper. A gap of a defined width is between the walls of the separation device 32 and the inner surface of hopper 30 to allow the powder to be separated and carried to the receiving container 33.

The above described magnetron sputtering device and individual variants of its embodiment provide the embodiment of method of production of a nanomaterial in vacuum and variants of the embodiment. Below are explained the peculiarities of the method of production of nanomaterial in vacuum and the individual cases (variants) of its embodiment.

The magnetron sputtering device (see Figures 1, 3 and 4) for production of nanomaterial in vacuum works as follows:

After reaching the ultimate vacuum (1C) ⁴ Pa) in the vacuum chamber 1, the inert gas argon Ar (or, in the case of reactive sputtering, Ar + 0 ₂ , Ar + N or others) is supplied to it through the working gas supply system 26 and as a result, the working pressure of order lO^-lO ² Pascal (Pa) is created in the vacuum chamber.

The coolant supplied to the liquid cooling system 4 of the cathode assembly (see Figures 1, 3 and 4), as a result of passing through the cathode assembly 3 and the whole system and, finally, after flowing out from the output holes (shown by arrows), under a certain pressure, affects the blades 9 of the disc carrier 10, which has the shape of a hollow cylinder, that causes the rotation of the disc carrier 10, disk 7 and groups of permanent magnets 8 fixed on it. The turbulent flow of the coolant along the spiral trajectory moves to the channel of liquid cooling system 4 of cathode assembly thus providing the effective cooling of cathode assembly 3, disk target carrier 6 and disk target 5. After the above operations the constant or pulse voltage is applied between the cathode assembly 3 with negative electrical potential and anode 2 with zero potential, due to which between them there generates an inhomogeneous electric field and excites the anomalous glow discharge. The presence of a closed magnetic field 27 on the surface of the disk target 5 contributes to the localization of the formed magnetron plasma 28 in the immediate vicinity of target 5, the configuration of which coincides with the zone of active sputtering of target 5. The width of this zone is determined by the distance between the adjacent magnets with opposite polarity, included in the groups of permanent magnets 8, and repeats the shape of a closed loop created by the groups of magnets 8. A group of permanent magnets 8 placed above the fixed disk target 5 rotates in a plane parallel to the surface of disk target 5 in such a way that the axis of its rotation passes through the center of disk target 5, causing generation of a rotating magnetic field 27 (Figures 1, 3 and 4), which has a shape of closed loops 12 and 13, consisting of the said line of involutes (see Figure 2) and its movement.

As a result of the ion bombarding, the electrons emitted from the surface of the disk target 5 are captured between the inputs and outputs of the magnetic field power lines 27, which causes their movement along the complex cycloid trajectories in the active zone of sputtering having the shape of a closed loop. As a result, electrons are caught up in a trap which is created on the one hand by the magnetic field power lines 27 which rotate electrons to the surface of target 5, and on the other hand - by the surface of target 5, which drives electrons back. The electrons perform cyclotron motion in this trap (in the toroidal plasma region 28) until they make several ionizing collisions with the working gas molecules or macrodroplets of the dispersed material of target 5, as a result of which they lose the energy received from the electric field. Thus, before reaching anode 2 a greater part of the electron energy is used for ionization and excitation of the said macrodroplets, which greatly increases the efficiency of the process of transition of the material of target 5 to the nanoparticle materials.

One of the peculiarities of magnetron sputtering systems is the localization of anomalous glow-discharge plasma 28 above the active sputtering zone of disk target 5 and near it. This plasma has the shape of a torus and the degree of ionization reaches its maximum in its central part, on the closed loop trajectory above the sputtering region. Localization of plasma 28 on the midline of the active sputtering region is caused by heterogeneity of electric and magnetic fields.

The rotation rate of the magnetic system is automatically controlled by the magnetic system rotation speed control unit 15 of the presented device. Along the rotation of the magnetic system the permanent magnets 17 fixed on the housing 16 rotate and interact with the fixed magnetic sensor 20. In this sensor a sequence of electrical pulses induces, the frequency rate of which is proportional to the rotation speed. These pulses are supplied to the software control unit 23, which is equipped with the application software. The software control unit 23, controlled by the above software, generates a magnetic system rotation rate corrective command, which is supplied to the piezoelectric elements 21. Taking into account the current value of the speed of rotation of the magnetic system and the processes occurring in the reactor forming the nanoparticles, the software control device 23, controlled by the software, produces a control signal that corrects the rotation speed of the magnetic system, which is fed to the piezoelectric elements 21. According to the value of the control signal, the geometric dimensions of the piezoelectric elements 21 change and, accordingly, the value of friction force between the brake ring 18 mounted on the movable housing 16 and the stationary piezoelectric elements 21, which are in mechanical contact with each other, change also. Consequently, the rotation rate is increased or decreased, which results in the optimum value of the rotation rate of the magnetic system. If the value of the control signal is zero, the geometric dimensions of piezoelectric elements 21 are minimal, so that they do not touch the brake ring 18 and, accordingly, the rotation rate is maximum.

The method of production of nanomaterial in vacuum by means of a magnetron sputtering device in accordance with the invention stipulates the following:

Through rotating the magnetic system located in the magnetron sputtering device (see Figures 1-4), in a parallel plane towards the surface of the disk target 5 formation of a rotating magnetic field with a configuration of closed loop 12 and 13 , containing the involutes of the circumference of a circle of a specific radius 11, the rotation axis of which passes the center of the target 5; creation of an active zone of sputtering between the inputs and outputs of magnetic field power lines 27 on the surface of the disk target 5 by applying an electric field and a rotating magnetic field to the disk target surface; creation on the disk target surface a gaseous discharge with a shape of a closed loop 12 and 13 consisting of the involutes of the circumference of a circle of a specific radius 11, and toroidal magnetron plasma region 28 over the active zone of sputtering by manipulating the values of working gas pressure in the vacuum chamber 1 and the power applied to the disk target 5; formation and dispersion of cathode spots by ionization of working gas atoms in the toroidal magnetron plasma region 28 and their acceleration in dark cathode region of glow discharge plasma in close proximity to the surface of the disk target 5; the cascading decay of the formed liquid macrodroplets of the disk target material in the toroidal magnetron plasma region and curing of nanoparticles formed as a result of such decay.

In addition to the above operations, the given method of production of nanomaterial in vacuum also includes the creation of a nanoparticles forming reactor which in the process of sputtering of the disk target material provides for the compact arrangement of the macrodroplets flow with a closed loop configuration generated in the active zone of sputtering and toroidal plasma cascading decay zones; the continuous movement of the created reactor over the disk target surface, regulation of the distance between the inputs and outputs of magnetic field power lines on the disk target surface, and the automatic control of the rotation rate of the rotating magnetic field, taking into account its current values and the specific parameters of the processes in the created reactor; at the same time, the formation and dispersion of the cathode spots additionally provides for the bombardment of the disk target with working gas ions, the supply of the macrodroplet flow of the liquid material of the disk target resulting from the formation and dispersion of cathode spots to the magnetron toroidal plasma region; and the cascading decay of the liquid material of the disk target additionally provides for carrying out of the process of the decay in the toroidal magnetron plasma decay in the conditions of recharging of liquid macrodroplets in the toroidal magnetron plasma and development of Rayleigh or capillary instability process, and carrying out of the process of cooling and curing of nanoparticles formed as a result of cascading decay - outside the region of the toroidal plasma.

In connection with the above-mentioned nanoparticles forming reactor, it should be noted that at the moment of formation and dispersion of cathode spots in this reactor the initial division of liquid droplets of material of the disk target takes place. After that, the flow of these macrodroplets is supplied to the toroidal magnetron plasma region. In order to ensure the effective process of recharging liquid macrodroplets and the effective development of Rayleigh or capillary instability and, thus, their cascading decay, i.e. the production of nanoparticles in the plasma region, it is necessary to strictly control the time interval of presence of liquid macrodroplets in the toroidal magnetron plasma. And this time is directly related to the magnetic field rotation speed.

This software is a program of control of the technological process that ensures the control of the value of percentage of macrodroplets in the active zone of sputtering of the surface of disk target 5. Predominantly, a specific technological task is performed by automatically controlling the magnetic system rotation rate using this software, which is based on the data obtained by simulating the current value of the magnetic system rotation speed, the process of sputtering of the disk target and the processes occurring in the nanoparticles forming reactor, either experimentally, or using a combination of these two methods. The automatic control, which is performed by the magnetic system rotation rate control unit 15, provides the increase in the efficiency of the nanoparticles forming reactor.

Below is a description of individual variants of the embodiment of the method of production of nanomaterial in vacuum with the assistance of the presented magnetron sputtering device, performed according to the invention:

When embodying one of the variants of the method of production of nanomaterial by with the assistance of magnetron sputtering device, during the technological process of formation and dispersion of the cathode spots, the non sputtered regions of disk target 5 are sputtered additionally by their intensive bombardment with working gas ions, creating the active sputtering zone through the alternating wave-like movement of the flow of ions which effect on the non sputtered regions with the maximum, symmetrical in both directions decreasing intensity and automated control of the magnetic field rotation rate.

Another variant of embodiment of the method of production of nanomaterial with the assistance of magnetron sputtering device provides for the production of nanomaterial in the form of synthesized nanoparticles on the substrate. This variant additionally provides for the synthesis of the obtained cured nanoparticles on the surface of the substrate. At that the planar substrate carrier 24 or planetary substrate carrier 30 is placed in the working region of the magnetron sputtering device in such a way that they are directed towards the disk target 5 and at a certain distance from it. Another variant of embodying the method using the magnetron sputtering device also provides for the production of nanomaterial in the form of synthesized nanoparticles and additionally envisaged:

Continuous movement of the magnetron toroidal plasma region under the effect of a rotating magnetic field on the disk target surface 5; at that, the process of curing of nanoparticles formed as a result of cascading decay additionally provides for the beginning of the curing process after the nanoparticles leave the toroidal plasma region into the vacuum space between the disk target surface and the planar or planetary substrate carrier; providing the diffusive, random or thermal movement of the produced nanoparticles and their free fall along a spiral trajectory in the vacuum space between the disk target surface and the planar or planetary substrate carrier; and the final cooling and curing of the nanoparticles produced.

In connection with the above described variants of embodiment, it should be noted that the active zone of sputtering in the planar magnetron sputtering device is located on the surface of the disk target 5 (see Figures 1, 3 and 4) between the inputs and outputs of power lines of magnetic field 27 and above the same zone, in the toroidal plasma ionization region 28, in its immediate vicinity, where the effective ionization of working gas atoms takes place. In the dark cathode region of the glow discharge plasma, the ionized working gas atoms are accelerated and the cathode spots are formed and dispersed by alternating intensive bombardment of the surface of the disk target 5 with positive working gas ions; the movement of the flow of charged liquid metal macrodroplets formed and dispersed on the active sputtering zone of the of disc target 5 is directed vertically from top to bottom from this surface to the ionization region of toroidal plasma 28. In this region, as a result of collision of metal droplets with electrons in the plasma, they acquire a negative charge; they are recharged to a critical value, i.e. to the development of the process of Rayleigh (capillary) instability, and their cascading decay. The variant of the embodiment of the method, which ensures production of nanomaterial in the form of cured monodispersed nanopowder, provides for the separation of nanoparticles, the passage of the obtained powder to receiving container 33 and its accumulation in this container using the funnel-shaped hopper installed in the working region of the vacuum chamber of the magnetron sputtering device, separation device and receiving container installed at the output of the hopper.

According to one more variant of embodiment of the method using the magnetron sputtering device, which also provides production of nanomaterial in the form of cured monodispersed nanopowder, the following operations are performed additionally:

The continuous movement of the toroidal magnetron plasma region under the influence of a rotating magnetic field on the surface of the disk target 5; curing of nanoparticles formed as a result of cascading decay, which additionally provides for the beginning of the curing process after the nanoparticles leave the toroidal plasma region into the vacuum space between the surface of disc target 5 and the nanopowder receiving container 33; ensuring diffusive, random or thermal movement of the obtained nanopowder and their free fall along a spiral trajectory in the vacuum space between the surface of the disk target 5 and the nanopowder receiving container 33, and final cooling and curing of the produced nanopowder.

According to one of the variants of the embodiment of the method using a magnetron sputtering device for production of nanomaterial in the form of a film of coagulated particles on substrate 25 and spherical nanoparticles or quantum dots sputtered in the volume, the planar substrate carrier 24 or planetary substrate carrier 30 is placed in the vacuum chamber 1 of magnetron sputtering device at such a distance from the surface of the disk target 5, which provides for maintaining the temperature level of nanoparticles produced as a result of cascading decay on the substrate and creation of the conditions for formation of isolated quantum dots in the volume of the film from the disk target material.

According to another variant of embodiment of the method using a magnetron sputtering device for production of the nanomaterial in the form of a film with an amorphous structure consisting of individual spherical nanoparticles, the planar substrate carrier 24 or planetary substrate carrier 30 is placed in the chamber 1 of the magnetron sputtering device at such a distance from the surface of the disk target 5, which provides for maintaining the temperature level of nanoparticles produced as a result of cascading decay on the substrate and creation of the conditions for formation of the Van der Waals bonds or metal bonds.

In connection with the last two variants of embodiment of the method using the magnetron sputtering device, it should be noted that if the planar substrate carrier 24 or planetary substrate carrier 30 is placed at a closer distance from the surface of disk target 5, then the nanoparticles formed as a result of cascading decay which temperature is close (above or below) the boiling point, when been deposited on the substrate and approaching each other to the close distance, will fuse (coagulate) and therefore the nanoparticles will not be formed. Nanoparticles should fully maintain the spherical form. However, a certain demand for such films may also exist.

If this distance is increased, the temperature of the nanoparticles will decrease. It is known that in this case the mechanism of their cooling is the auto-electronic emission. Noteworthy is the fact that individual nanoparticles with the same charge (the same polarity) are repulsed by free fall along the spiral trajectory, and their fusion (coagulation) during fall is completely excluded.

If the planar substrate carrier 24 or planetary substrate carrier 30 is placed at such a distance where the conditions for the Van der Waals bonds (metal bonds) are formed between the nanoparticles deposited on the substrate, the nanoparticles with an amorphous structure will form. This structure consists of individual spherical nanoparticles, and films of such particles are in great demand. As the distance between nanoparticles continues to increase, the nanoparticles cool down to the level that they do not affect each other and the nanomaterial is formed in kind of the integrity of spherical nanoparticles, i.e. the monodispersed nanopowder. At present, there is a huge demand for such nanopowders on the market.

Below is an example of embodiment of the method of production of nanomaterial in a vacuum.

Example of method embodiment. The method of production of nanomaterial in vacuum and technological modes of sputtering the disk target 5 using the magnetron sputtering device are presented in the table below.

As noted above, the generation of metal macrodroplets is carried out with the initiation of cathode spots of the material of disk target 5 by its bombardment with the ions of the working inert gas (argon). Fig. 6, given in the scientific article "Planar Magnetron Sputtering Device: a New Generation of Magnetron Sputtering Design and Technology, (Berishvili Z. V. at al), published in the Journal of Physical Science and Application, USA, ISSN 2159-5348, Volume 7, Number 5, 2017, pp. 28-39, shows a photo of an aluminum disk target of a planar magnetron sputtering device (a) and a drawing of its profile (b) before sputtering as well as a photo of a disk target (c) and a drawing of its profile (d) after sputtering and complete exhaustion of the resource.

Photo (c) clearly shows the light spots along the contour of the involutes. The analysis revealed that these "light spots" are the integrity of craters formed by sputters of microparticles and, partially, of macrodroplets, which resulted as a result of intensive bombardment of the disk target surface by argon ions in the active sputtering zone. At this time, cathode spots, i.e. sputters of microdroplets and macrodroplets, are formed on the surface of the disk target material, and the corresponding craters are formed in their place.

The efficiency of the drip phase generation along with the physical properties of the material of disk target 5 depends on the intensity of the ion bombardment, which, along with the device design, is determined by the controlled technological parameters of the magnetron sputtering process.

In addition, the average energy of electrons and electron flux density in the magnetron toroidal plasma 28 region always exceeds the corresponding values of electric discharge plasma in the analogues, which significantly increases the efficiency of the proposed method.

The flow of the formed aluminum macrodroplets of the disk target 5 passes to the nanoparticles forming reactor where the macrodroplets from the active sputtering zone, placed between the inputs and outputs of power lines of magnetic field 27, move to the region of ionization of toroidal plasma 28. In this region, aluminum macrodroplets, as a result of collision with electrons in the plasma, acquire a negative charge; they are recharged to a critical value, i.e. to the development of the process of Rayleigh (capillary) instability and their cascading decay. After the production of aluminum macrodroplets in the magnetron plasma reactor, their cascading decay and transition to the nanostructure as a result of movement of the reactor along the surface of disk target 5, the formed nanoparticles leave the toroidal plasma 28 region and the process of their curing (cooling) in the vacuum medium of working gas begins.

According to the presented invention, the optimal conditions for curing and condensation of formed nanoparticles are created. In particular, after the release of nanoparticles from the toroidal plasma 28 region, the process of their curing (cooling) in the vacuum medium of working gas (argon) begins. Since the process of sputtering the disk target 5 runs from top to bottom, the formed nanoparticles, by a free diffusive (random) fall along the spiral trajectory move towards the substrate 25, where they are synthesized or the formed monodispersed powder passes to the receiving container 33.

References

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