In the last decade, to improve the reliability and performance of machinery, electronics and medical equipment, the electrodeposition methods of surface modification are increasingly replaced by environmentally friendly vacuum-plasma systems of multi-component thin-film structures deposition, in particular, on the basis of the magnetron and vacuum-arc gas discharge. In addition, the combination of magnetron and vacuum arc sources in a single sputtering system allows to cover almost an unlimited range of deposited materials, including metals, semiconductors and insulators, and to provide a high quality and rather high rate of deposition. However, targeted control of the nanostructure, phase and chemical composition of the deposited layers requires additional hardware. The use of the assisting ion bombardment of the substrate simultaneously with the deposition of films and the implementation of the hybrid plasma system (GPS) solves this problem. The sources on the basis of high density plasma, which can be obtained by using inductive RF discharge placed in an external magnetic field, are especially effective. Such plasma sources are called helicon sources. Helicon source, in contrast to the conventional one, in which only power can be adjusted, provides additional capabilities to control the composition and structure of the plasma, namely the size and configuration of external magnetic fields. Regulation of these parameters allows control of plasma density and its spatial distribution in the area of the substrate holder [1–3].
Innovative Helicon-TM system is designed for research and development of a wide range of new controlled technological processes for deposition of functional coatings of various materials by magnetron sputtering and / or arc evaporation in plasma of helicon discharge. Plasma-enhanced deposition process with a controlled plasma density and energy provides a controlled nanostructuring of the coatings that can be used in various fields of science and technology (nano-, micro-, opto -, photo- and radio electronics, medicine, energy storage, etc.). Helicon discharge provides in the area of the substrate holder the plasma density of up to 1012 cm–3, and applied RF bias – the ion energy from 10 to 300 eV. This allows to develop innovative technological processes of plasma-enhanced deposition and also of dry etching and cleaning. Coating with simultaneous use of physical vapor deposition and plasma enhanced chemical vapor deposition allows to implement enhanced control of the characteristics of the resulting structures. The design of the system, which combines magnetron, arc and magnetic-activated inductive RF discharges is shown in Fig.1. The system consists of two parts. The main part is a metal process chamber of the cylindrical shape with a diameter of 500 mm and a height of 350 mm. At the bottom of the chamber there is a rotating table for placement of processed samples. Two optical windows are located opposite each other above the table for the spectrometric studies of plasma parameters. The magnetron and vacuum-arc sources are installed on the side faces of a process chamber. This paper presents the results of experiments with the use of only magnetron. A quartz discharge chamber with a length of 250 mm and a diameter of 220 mm is mounted above the main chamber. The upper volume of the chamber is closed by a blind glass flange, and the bottom – by a metal flange with an outlet that provides the output of the plasma into the main chamber. The magnetic system consists of two electromagnets located in the upper and lower parts of a process chamber. Electromagnets create a divergent magnetic field in the discharge chamber and of slightly diverging to the substrate (with a predominant longitudinal component) magnetic field in the processing chamber. The magnetic field in each point of the volume of the process chamber is determined by the Itop and Ibot currents flowing through the upper and lower electromagnets respectively, and the same value of magnetic field induction can be achieved by setting different ratios between the currents of the magnets. The table shows the values of magnetic field induction achieved in the area of the antenna, in the center of the process chamber, and near the substrate, at various values of Itop, Ibot. The solenoidal antenna located on the outer surface of the quartz chamber is used for the excitation of inductive RF discharge. The ends of the antenna are connected through the matching system to the RF generator with an operating frequency of 13.56 MHz and output power of up to 1 000 W. The RF generator is used for excitation and sustaining of the magnetron discharge. The results of the study parameters of the helicon plasma source showed the promise of the chosen design of the GPS based on mutual influence of two types of discharges, which ensures an increase in plasma density and concentration of sputtering atoms. The optimal design includes a double-chamber inductive source with solenoidal antenna and a magnetic system, allowing to create in the process chamber a uniform magnetic field with induction of not less than 7 mT, and in the discharge chamber – a slightly diverging magnetic field. The proposed configuration provides effective control of structure of thin-film coatings, which is very useful in various applications. For example, in the manufacture of thin-film battery layers it is particularly important to have a well-developed structure of the coatings for increasing the energy capacity. Fig.2 shows the structure of anodic films based on silicon nanocomposites, which are obtained by magnetron sputtering of a silicon target containing 10% of aluminum, with and without bombardment of the growing films by the flow of accelerated ions of argon from the helicon source. The illustration shows that the impact of the plasma of assisted helicon discharge leads to a fundamental change of the structure of growing film. ■ The project is executed at financial support of the Ministry of education and science of the Russian Federation. Agreement No. 14.576.21.0021 from 30 June 2014. The unique identifier of applied research (project) RFMEFI57614X0021.