RU2371514C1 - Dual magnetron spray-type system - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to plasma technology, particularly to dual magnetron spray-type system and can be used for application of thin films of metals and its compounds in different field of technologies. Dual magnetron spray-type system contains located in one plane nearby each other two planar magnetrons, each of which contains casing, magnetic system and flat plate target, and feed system with changed polarity. Both magnetrons are located in additional total casing insulated from it. Between planar magnetron it is located additional magnetic system, polarity of which coincide with polarity of central magnet of magnetic system of each magnetron. Magnetrons are connected to feed system with changeable polarity so, that at the same moment of time voltage sign on magnetrons is opposite.

EFFECT: development of effective dual magnetron spray-type system.

2 dwg

Description

The invention relates to a plasma technique and is intended for depositing films of metals and their compounds synthesized by the interaction of atoms sprayed from the surface of a metal cathode and a gaseous medium onto the surface of solids.

The main assembly unit for coating is a magnetron spray system. The magnetron sputtering system comprises an anode and a cathode assembly, which consists of a magnetic system and a sputtering target. The magnetic field lines are located along the target surface. When a constant voltage is applied between the cathode (target) and the anode, a glow discharge is ignited in the working gas medium. A magnetic field localizes the plasma directly at the target. Electrons emitted from the target surface under the action of electric and magnetic fields move along its surface along complex cyclic trajectories, ionizing the atoms of the gaseous medium. This leads to an increase in the concentration of ions in the plasma and an increase in the sputtering rate of the target.

Known designs of planar magnetron sputtering systems (see Danilin B.S., Syrchin V.K. Magnetron sputtering systems. - M.: Radio and Communications, 1982, p. 11) suggest the presence of a flat cathode assembly and anode connected to a constant source voltage. The cathode assembly in the most general case contains a magnetic block and a water-cooled target, which is a plate of atomized material covering the magnetic block.

However, reactive sputtering of Sn, Ti, or Al at a constant current is inefficient due to process instability and the formation of an arc, which occurs at the cathode coated with an oxide insulating layer. A dielectric film reduces the yield of atoms upon sputtering of a target and changes its emission properties. Arc formation can be reduced by periodically unloading the cathode, for example, by using an alternator. However, this does not prevent the deposition of insulating material on the walls of the chamber, which leads to quenching of the discharge (“the problem of the disappearing anode”). Spraying at high frequencies, as a possible alternative, is unacceptable due to the low spraying rates of the desired materials.

The dual magnetron sputtering system described in US Pat. No. 6,363,668 B1, C23C 14/34 was selected as the prototype. Sputtering installation with two longitudinally placed magnetrons / Johannes Struempfel; Guenter Beister; Wolfgang Erbkamm; Stanley Rehn, all of Dresden (DE). - Published on March 26, 2002. It contains two planar magnetrons located next to each other in the same plane. Each of the magnetrons contains a housing, a magnetic system, and a target cathode. Between the magnetrons there is a magnetic shunt made of magnetic steel, which redistributes the magnetic fields, linking the magnetrons to each other. Magnetrons are connected to a power system with a changeable polarity. When a negative potential is applied to magnetrons, the target is sputtered by ions of the working gas, and when positive, plasma electrons are deposited on the surface and discharge the dielectric film, cleaning the cathode.

The design of magnetron sputtering systems should provide a high atomization rate, minimal negative impact on the processed products, uniform coating thickness, high reliability, etc. Here, the construction of the magnetic system plays an important role, since the distribution of the electric potential in space, and, consequently, the mode of combustion of the discharge, depends on it.

Thus, the object of the invention is to provide a magnetron sputtering system that stably operates during the deposition of metal oxides and provides high deposition rates.

The technical result of the invention is to increase the uniformity of the process of sputtering the target in time with an increased sputtering coefficient.

To solve this problem, the proposed system, like the prototype, contains two planar magnetrons located in the same plane next to each other. Each magnetron, in turn, contains a body, a magnetic system, and a flat target. Both magnetrons are connected to a polarity reversible power system.

Unlike the prototype, both magnetrons are located in an additional common housing isolated from it, and between the magnetrons there is an additional magnetic system, the polarity of which coincides with the polarity of the central magnets of planar magnetrons. The power system is connected to the magnetrons so that the pulses of the opposite polarity are simultaneously fed to the magnetrons.

The use of a common housing for two planar magnetrons makes it possible to isolate them from the walls of the vacuum chamber and prevent dusting of the magnetron bodies, which would lead to instability of the discharge burning. The introduction of an additional magnetic system increases the strength of the magnetic field, preventing the escape of electrons from the system, which in turn increases the rate of deposition of films. Bipolar supply of magnetrons allows you to transfer the function of the anode from one cathode node to another. In one half-cycle, the cathode is oxidized, in the other it is purified.

The invention is illustrated by graphic materials, where figure 1 schematically shows the design of the proposed dual magnetron sputtering system, and figure 2 shows a block diagram of one of the possible options for implementing a power source with a variable polarity.

Planar magnetrons 1 and 2 are located in the same plane next to each other and are fixed in a common housing 10 using ceramic insulators 8. In this case, both magnetrons are isolated from each other. A planar magnetron 1 consists of a housing 3 made of non-magnetic material and which is an external magnetic circuit. In the center of it there is a block of permanent magnets 4, which serves as a source of the magnetic field of the device and at the same time as the central magnetic circuit. Along the perimeter of the magnetron there are side magnets 9, which are a side magnetic circuit. The magnetron 1 body is covered by a flat target 5. The magnetron 2 has a similar design. Its body 3a is also made of non-magnetic material and has in the center a block of permanent magnets 4a, and on the sides there are magnets 9a that perform the same functions as the magnet system of magnetron 1. The body of magnetron 2 is closed by a flat target 5a. Between the planar magnetrons 1 and 2 there is an additional magnetic system 6 made of permanent magnets, the lines of force of which are closed to the magnetic systems of each of the neighboring magnetrons. The polarity of the additional magnetic system coincides with the polarity of the central magnets 4 and 4a.

The power system is shown in figure 2 and is a switching power supply having two outputs in the number of planar magnetrons. One output is connected to one planar magnetron, the second to another. At the first moment of time, a negative voltage is applied to one planar magnetron, and a positive voltage to the second. Then, using the Converter 14, the polarity is switched at both outputs of the power supply. The process of switching the polarities is controlled by the processor 13, the current and voltage supplied to the magnetrons are set using the controls 12 and are displayed using the light indication 15 on the display 11.

The device operates as follows.

Permanent magnets 4, 4a, 9, 9a, and 6 create a longitudinal magnetic field, the location of the lines of force 7 of which are shown in figure 1. A positive voltage is connected to one planar magnetron from the power source, and a negative voltage to the other. Thus, one magnetron is the cathode and the other is the anode.

When a negative potential is applied to magnetron 1, it begins to attract positively charged working gas ions from the plasma. Accelerated ions bombard and sputter target 5, simultaneously transferring their charge to it. In this case, the target 5 accumulates a positive charge. The field of this charge compensates for the initial field of the magnetron, which is under the negative potential, and further sputtering becomes impossible, since ions from the discharge are not attracted to the target 5. At the same time, a positive potential is applied to magnetron 2, and the second magnetron acts as an anode. Then the polarity of the voltage at the magnetrons changes. After changing the polarity, a positive potential is applied to magnetron 1, and it attracts electrons that neutralize the charge of ions, turning them into atoms, thereby cleaning the target 5 of magnetron 1. At this time, magnetron 2 performs the function of a cathode. Those. Ions accelerated from the plasma of the working gas bombard the target 5a, which is sputtered and accumulates a positive charge on it, inhibiting the sputtering process. At the next polarity reversal, the target 5, purified from oxides, begins to be sprayed.

The function of the anode is sequentially transferred from one cathode assembly to another. Thus, targets 5 and 5a are alternately sprayed and cleaned. An electric discharge burns between a pair of magnetrons 1 and 2, and dusting the surface of the working chamber with oxide films does not affect the properties of the discharge, i.e. the design is free from the disadvantages associated with the "problem of the disappearing anode."

The change of polarity on magnetrons occurs with a frequency of 1-100 kHz. A closed magnetic field at the surface makes it possible to better hold the discharge plasma directly at the target 5. The presence of an additional magnetic system 6 prevents the escape of electrons from the system. This leads to a significant increase in the degree of plasma ionization, which in turn increases the sputtering rate of targets 5 and 5a, and, consequently, increases the rate of deposition of films. The simultaneous supply of negative and positive potentials to magnetrons allows to obtain high-quality coatings, because sputtering occurs continuously and during the cleaning of one of the magnetrons, the substrate is not contaminated (at this time, sputtering by another magnetron).

Thus, the proposed design of the MPC allows you to spray oxide films with a higher speed.

Claims (1)

A dual magnetron sputtering system containing two planar magnetrons located in the same plane next to each other, each of which contains a housing, a magnetic system and a flat target, and a power supply system with a changeable polarity, characterized in that both magnetrons are placed in an additional common housing isolated from between it, between planar magnetrons there is an additional magnetic system, the polarity of which coincides with the polarity of the central magnet of the magnet system of each magnetron, and the magnet us are connected to a power supply system with variable polarity in such a way that one and the same moment the polarity of the voltage across the magnetrons is opposite.

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