RU203823U1 - Magnetron sputtering device for synthesizing an inhomogeneous film on a substrate surface - Google Patents

Abstract

The utility model relates to a magnetron sputtering device for synthesizing an inhomogeneous film on a substrate surface. The said device contains a vacuum chamber, an anode, a target cathode and a magnetic block located in the vacuum chamber. The magnetic block consists of solenoids located under the target cathode orthogonal to the electric field lines, and solenoids located above the anode surface orthogonal to the electric field lines. The solenoids located above the anode surface are rotated 90 degrees in their plane relative to the solenoids located under the target cathode. Solenoids, orthogonal to the planes of the anode and target cathode, are located parallel to the electric field lines along the perimeter of the target cathode and anode. Provides the ability to control the distribution of lines of force and the magnetic field strength in the discharge gap and implement their various configurations that determine the redistribution of the ion flux of the deposited material on the substrate surface in accordance with the required distribution of the material and / or its properties over the substrate. 2 ill.

Description

The utility model belongs to the class of devices that make it possible to apply a high-quality coating, including nanoscale, from magnetron plasma.

The use of magnetic fields in sputtering systems makes it possible to reduce the gas pressure in the vacuum chamber and ensure its almost one hundred percent ionization, which has a positive effect on the purity of the synthesized thin films.

If the lines of force of the electric and magnetic fields are parallel, then the trajectory of the electrons is a spiral with a continuously changing step: they rotate around the line of force of the magnetic field due to the transverse component of the velocity and move uniformly along the lines of force of both fields.

Magnetron sputtering in crossed (orthogonal) electric and magnetic fields is currently the most popular method for the synthesis of nanoscale films. With this technology, the trajectories of electrons, even in a uniform magnetic field, are complex spatial curves and are difficult to model and analytically calculate. Therefore, empirical concepts are still of decisive applied importance. When analyzing the motion of particles in a magnetron discharge, it is necessary to take into account the limitation of the discharge volume by the electrodes, the processes on their surfaces, and the real distribution of the electric field in the interelectrode gap. The particle trajectories are influenced by the configuration of the electrode system, the strength and the configuration of the magnetic field.

Until recently, the goal of all technological developments was to obtain the most perfect and homogeneous film coatings. However, recently there has been a tendency towards the synthesis of inhomogeneous films, especially in the nanoscale range. Moreover, they can be heterogeneous in various parameters - in composition, in thickness, in structure, in some properties, etc. This is partly due to the development and application of the fractal approach to technological processes and the latest achievements of fractal physics and geometry. The use of a gas discharge in magnetron sputtering devices (MRU) is beyond competition.

To implement such inhomogeneity, you can, for example, use structured electromagnetic fields of the visible range, introduced into a vacuum chamber during the synthesis of films [Method for producing thin films with a fractal structure. Serov I.N., Margolin V.I. RF patent for invention No. 2212375, priority dated November 14, 2002, issued on September 20, 2003, MKP 7 В82В 3/00, Publ. 20.09.2003, Bul. No. 26.] But on this way, enormous difficulties arise, associated both with the creation of devices that implement such fields, and with their "disposability" - if it is necessary to change any element of the structure of the field or the synthesized film, it is necessary to change the whole device - again it developing and designing.

More expedient and technologically advanced is the use of magnetron sputtering devices with an inhomogeneous controlled magnetic field in the discharge gap. Such a field will affect the passage of ions from the cathode to the anode-substrate, and direct different parts of the flow to the corresponding localization of the substrate, thus forming local zones of inhomogeneity.

In the work [Study of plasma characteristics in an unbalanced magnetron sputtering system by A.A. Soloviev, N.S. Sochugov, K.V. Oskomov, S.V. Rabotkin // Plasma Physics, 2009, volume 35, no. 5, p. 443-452] in order to study the formation and transfer of charge carriers in a magnetron discharge with an unbalanced magnetic field configuration, probe measurements of the plasma characteristics and ion energy were carried out in the region extending from the magnetic trap at the cathode surface to the substrate.

At present, very little is known about the spatial distributions of plasma parameters, especially in magnetrons with an unbalanced magnetic field configuration. Therefore, the main task of the work of Soloviev et al. Was the experimental determination of the distribution of plasma characteristics in the space between the cathode and the substrate in a magnetron sputtering system with an electromagnetic coil, which allows changing the configuration of the magnetic field above the cathode surface within wide limits.

It was shown that in order to increase the plasma density in the region of the substrate, it is necessary to create an axial magnetic field in the space between it and the magnetron, the magnitude of which is sufficient to effectively confine electrons and prevent their escape to the chamber walls. In this case, the plasma potential can decrease to negative values, and the characteristics of the plasma in the cathode-substrate space are distributed very unevenly, which can be used for the synthesis of inhomogeneous films. The energy distributions of ions in a magnetron discharge are nonequilibrium, have a maximum corresponding to thermalized particles ionized at the plasma potential, and a high-energy tail with energies up to 20-30 eV. The intensity of the high-energy tail in the energy distributions of ions depends on the pressure in the chamber, the degree of imbalance of the magnetron, and local distributions of magnetic fields.

Known magnetron sputtering system with an additional solenoid [Melnikov SN, Kundas SP, Svadkovsky IV. Modeling and numerical studies of the parameters of magnetron sputtering systems // Reports of BSUIR, 2007. - July - September (19), No. 3.], containing an anode and a cathode assembly located in a vacuum chamber, including a target cathode, a magnetic block of permanent magnets and an additional solenoid parallel to the electric field lines. The use of an additional solenoid installed in the gap between the target cathode and the substrate makes it possible to control the ion / atom ratio during deposition.

The disadvantage of using solenoids as magnets is the greater, in comparison with permanent magnets, the curvature of the lines of force, which leads to a gradient in the direction perpendicular to the lines of force and distorts the trajectories of the electrons. The curvature of the lines causes such a specific drift motion caused by a change in the direction of the magnetic field, such as centrifugal drift, i.e. drift under the action of centrifugal force for particles moving along the lines of force.

To increase the uniformity of sputtering of the target cathode, it is advisable to use long solenoids with a uniform magnetic field, as well as special magnetic circuits. However, this increases the mass, size and complicates the design of the installations, but does not lead to absolute uniformity of sputtering due to the escape of ions to the ends of the system and a decrease in their concentration at the edges of the MRS.

By the combination of essential features, the closest analogue of the proposed device is a magnetron sputtering device of a balanced type, which contains a vacuum chamber, anode, target cathode and magnetic block located in the vacuum chamber. (RU No. 134932 U1, IPC С23С 14 / 35.27.11.2013 "Magnetron sputtering system").

The disadvantage of the known device is the presence of permanent magnets located under the cathode assembly, which makes it possible to implement magnetron sputtering in orthogonal (crossed) fields. However, the use of permanent magnets presents significant inconveniences. Requirements for changing the configuration of the magnetic field lead to the need to change the location of the magnets or replace them altogether, which is not technologically advanced. In addition, the magnetic fields of permanent magnets cannot be adjusted.

The problem solved by the proposed utility model is to provide the ability to control the distribution of lines of force and magnetic field strength in the discharge gap and implement their various configurations that determine the redistribution of the applied material flow in space and on the substrate surface in accordance with the required distribution of the material and / or its properties on the substrate.

The problem is solved due to the fact that, just like the known, proposed magnetron sputtering device for synthesizing an inhomogeneous film on the substrate surface contains a vacuum chamber, an anode, a target cathode and a magnetic block located in the vacuum chamber. But, unlike the known one, the magnetic block consists of solenoids located under the target cathode orthogonal to the electric field lines, solenoids located above the anode surface orthogonal to the electric field lines, and the solenoids located above the anode surface are rotated 90 degrees in their plane relative to the solenoids located under the target cathode, and parallel to the electric field lines along the perimeter of the target cathode and the anode, there are solenoids orthogonal to the planes of the anode and target cathode.

The achieved technical result is the realization of the possibility to control the distribution of the field lines and the magnetic field strength in the discharge gap and to implement their various configurations that determine the redistribution of the applied material flow in space and on the substrate surface in accordance with the required distribution of the material and / or its properties over the substrate.

A magnetron sputtering device for synthesizing a non-uniform film on a substrate surface operates as follows. A gas discharge is ignited between the target cathode and the anode, and solenoids parallel to the electric field vector are turned on, as a result of which the trajectory of electrons in the discharge gap is lengthened, providing almost complete ionization of atoms and molecules of the sputtered material.

Then the solenoids located under the target cathode and above the anode are switched on and by selecting their parameters (current, voltage, if necessary, location), the required distribution of the magnetic field parameters in the interelectrode space is achieved, leading to the redistribution of this homogeneous flow of the sputtered material in accordance with the required parameters ... This can be an inhomogeneous but controlled distribution of impurities over the substrate surface; film thickness at different locations on the substrate; the latent structure of the synthesized film and other parameters.

Unfortunately, the selection of control parameters for solenoids is carried out empirically experimentally for each specific installation, specific material and specific problem to be solved. It is not yet possible to calculate the configuration of magnetic fields and their parameters even in general form due to the lack of an appropriate computational base and a specific understanding of the processes of interaction of inhomogeneous magnetic fields with the sputtered material occurring in the discharge gap.

The utility model is illustrated by drawings that do not include a vacuum chamber, where in FIG. 1 shows the design of the proposed magnetic spray device - side view, and FIG. 2 - top view, where 1 - target cathode; 2 - anode; 3 - solenoids located under the target cathode; 4 - solenoids located above the anode, orthogonal to the solenoids located under the target cathode; 5 - solenoids orthogonal to the planes of the anode and target cathode. Dotted lines show solenoids that are out of sight.

To test the performance of the proposed magnetron sputtering device, experimental studies were carried out on the basis of a modernized VUP-4M vacuum station equipped with an additional magnetron device according to the proposed utility model. Refined copper was sprayed. The selection of the parameters of the solenoids (voltage and current) made it possible to synthesize on the substrate a film of copper, non-uniform in thickness, which is a system of "hills" up to 1 µm in height and a film field between them 0.2–0.3 µm thick.

Claims (1)

Magnetron sputtering device for synthesizing an inhomogeneous film on a substrate surface, containing a vacuum chamber, an anode, a target cathode and a magnetic block located in the vacuum chamber, characterized in that the magnetic block consists of solenoids located under the target cathode orthogonal to the electric field lines, and solenoids located above the anode surface orthogonal to the electric field lines, and the solenoids located above the anode surface are rotated 90 degrees in their plane relative to the solenoids located under the target cathode, and parallel to the electric field lines along the perimeter of the target cathode and the anode, solenoids are located orthogonal the planes of the anode and target cathode.

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