Development of a Software and Hardware Complex for Controlled Anodic Oxidation

Introduction. Anodic oxide films of metals, both dense and nanostructured (nanoporous, nanotubular) are widely used in modern microelectronics. By liquid anodizing of multilayer thin-films structures it is possible to obtain not only sequential layered structures from oxides, but also periodic three-dimensional nanostructures, which is extremely difficult to make by other methods. The field of applications of anodic oxide films is expanding with the growth of the ability to control their parameters: thickness, structure, morphology. It is possible to vary the sizes of structural elements of anodic oxides by changing of anodizing parameters preseted by equipment: voltage, current density, electrolyte composition, anodic oxidation time. Along with this, there is the task of precise control over the process, which is carried out by registering of the dependences V(t), I(t), dV/dt(t), dV/dt(V) on the electrochemical cell in-situ. Information on dV/dt(V) can be used to study the characteristics of layers being anodized (thickness of thin metal films and transition layers, oxygen content in the films, surface roughness), especially in the case of multilayer thin film structures. In such a way, the manufacturing method can simultaneously be a research method. The creation of software and hardware complex that provides the necessary anodization modes and careful control of the output data in real time is relevant for our developments on nanostructured sensor substrates, and can also be useful for other applications. The purpose of the work. The work is devoted to the creation of an improved software and hardware complex for controlling the parameters of liquid anodising with extended ranges of operating currents and voltages, as well sampling rate. The complex is designed for the formation of anodic oxide films, both dense and nanostructured, and for studying the processes of formation of anodic oxides and thin-film structures during their anodization in-situ. Results. An advanced software and hardware complex for controlled anodizing has been created. Its development used a modular design principle with maximum separation of digital and analog circuits, optimized power supply circuits, adjustable signal sampling rate from the electrolytic cell, and a computer communication protocol. The improved device is designed to set and record current and voltage during the anodization in electrolytic cell where dense or nanostructured anodic oxide is formed in direct current mode or in constant voltage mode. When anodizing occurs in direct current mode, the range of currents set by the operator is 1 μA to 20 mA. When anodizing occurs in constant voltage mode, oxide formation is first carried out in constant current source mode, and when the preseted voltage value is reached, the transition from constant current mode to voltage source mode is automatically performed, while the current through the forming oxide film is recorded in-situ. The range of voltages that can be set by the operator: 0 – 200 V. The software provides the ability to visualize I(t), V(t), dV/dt(t), and dV/dt(V) on the computer in real time, the ability to average the output data, and further work with the data in various processing programs. Voltage and current recording is performed with a time resolution adjustable by the operator: 2,5 ms; 5 ms; 10 ms; 25 ms; 0,1 s; 0,5s. Conclusions. Owing to improvements in circuit design, the device's interference stability has been increased, stable operation of the measuring complex over a wide range of currents and voltages has been achieved, and the data reading interval has been reduced. The created software and hardware measuring complex makes it possible to perform controlled anodization on samples with different areas (from units to hundreds of mm2) on massive metals, thin films and multilayer thin-film structures. It can be used for research, development, and manufacturing of samples in areas related to the creation and study of dense and nanostructured anode oxides and nanomaterials based on them. The areas of application of the measuring complex include the development and manufacture of elements for optical and electrochemical sensors, electrochromic devices, solar cells, photocatalysis, new promising energy storage elements, and biomedicine (biosensors, implant coatings, drug delivery systems).