Persons

Тихонов Роберт Дмитриевич
Cand. Sci. (Eng.), Senior Researcher of the Research Laboratory of New Technological Processes, SMC “Technological Centre” (Russia, 124498, Moscow, Zelenograd, Shokin sq., 1)

Article author

Magnetic films of NiFe permalloy and CoNiFe ternary alloy have application in nano- and microelectronics products and in tightly-packed magnetic memory. The NiFe and CoNiFe coatings decrease corrosion and depletion in electrical devices; they are also used in electrocatalytic materials. Large stresses in magnetic films lead to deformation and instrument faults caused by film peeling off silicon substrate. In this work, to clarify the nature of the phenomena occurring during the electrochemical deposition of NiFe, CoNiFe films and leading to mechanical stresses, their study was carried out. It was demonstrated that a measurement of deflection of silicon substrates on an optical profilometer in the structure of Si, SiO, SiN, NiCr, Ni, after applying each of the CoNiFe or NiFe layers to the silicon substrate, allows the determination of mechanical stresses in films. It has been established that the deflection of the plates with SiN is negative and greater than with SiO. Deflection after applying NiCr and Ni layers is negative. Deflection of silicon wafers with ternary alloy CoNiFe films has a maximum value of 180 μm with a film thickness of 12 μm, and with permalloy NiFe films, a maximum value of 150 μm with a film thickness of 15 μm. Deflection after application of NiFe, CoNiFe is positive. Peeling of films is not observed. Difference in the deformation signs of Ni and CoNiFe or NiFe films and in the direct dependence of the silicon deflection on the thickness of NiFe and CoNiFe films makes it possible to bind mechanical stresses with hydrogenation and hydrogen release after the process. It has been determined that the magnetic susceptibility of NiFe permalloy films is lower than the triple CoNiFe system. The latter are promising for use in magnetic field converters.

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An amplification of magnetic induction in permalloy allows a several times increase of the sensitivity of magneto-semiconductor mycrosystems magnetic field. While using the permalloy films as the magnetic concentrators, it is important to exclude the anomalous codeposition of alloy components and to reduce the variability of technological parameters for optimum magnetic properties. In the work the chloride electrolyte with the pH correction by hydrochloride acid, which provides the congruent electrochemical permalloy deposition while heating has been proposed. The magnetic properties of the permalloy films, corresponding to bulk samples, have been determined. It has been shown that the magnetic properties of the permalloy films are sensitive to deviation of the composition from the ratio of 4.26 components. The control of accuracy of preparing an electrolyte for electrochemical deposition has been performed using the spectrophotometric investigation of chloride electrolyte. It has been established that the anomaly of the permalloy electrodeposition is associated with the main feature of iron ions-the existence of variable Valence iron with two or three values in the charge of ions during the hydrolysis of ions salts.

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The existing power MOSFET constructions have been presented. The issues of resistance reducing in the switched on state and of increasing vertical and planar power MOSFET speed have been considered.

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The use of chloride electrolytes for electrochemical deposition of NiFe permalloy seems to be promising because the sulphate electrolytes in presence of sulphur are non-stable. The magnetic properties of NiFe are very sensitive to rejection of the whole component o 4.26. In this work the control of preparing the electrolyte for electrochemical deposition has been conducted using the spectrophotometric investigation of the chloride electrolyte. The analysis of the electrolyte absorption spectrum and scattering of light by particles of iron hydroxide colloid has revealed that the dissociation of the two-valent iron and the mechanism of anomalous electrodeposition depend on temperature and affect the electrochemical deposition of the permalloy films. It has been noted, that the specific feature of the FeCl solution during hydrolysis of FeCl is the iron hydroxide precipitate (Fe(OH) in the form of colloid particles with the complex forming boric acid. It has been shown that from the chloride electrolyte with iron chloride solution filtration nickel is precipitated better than iron. It has been stated that normal congruent deposition of the NiFe alloy films takes place and the abnormal codeposition is excluded.

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High-permeability films of CoNiFe triple system form the basis for high-density magnetic data storage. Electrochemical deposition of CoNiFe films, as contrasted with «dry» processes, gives more homogeneous coating with lesser defect level and allows reinforcing the films thickness without stresses. This study investigates the nature of the phenomena taking place at electrochemical deposition of CoNiFe films and leading to the difference in the relative content of the elements in the electrolyte and in the film. The hydrogen exponent of chloride electrolytes was examined in the temperature range of 25-70 °C and electrochemical deposition of CoNiFe films at 70 °C was studied. It was demonstrated that CoCl, NiCl, FeCl salt solutions with concentration from 0,006 to 1 mole/l are characterized by complex process of ion balance formation in single and mixed solutions. The deposition of CoNiFe films was carried out from chloride electrolyte with a component content ratio of 1:1:1 at an average concentration of 0,083 mole/l of each component. It has been established that the content of the component in the film at electrochemical deposition of three-component solution CoCl, NiCl, FeCl with equal concentration of each component did not correspond to the composition of the electrolyte but was closest to the composition of the electrolyte at a decrease in the concentration of each component at high current density.

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A novel lateral high voltage MOSFET structure and its CMOS fabrication process have been presented. The properties of this structure have been investigated and optimized by the apparatus-technological simulation. For the devices with the drain breakdown voltage 250 V and 1000 V, some options of the structures most suitable for technological implementation have been found

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The sensitivity and the initial offset of voltage between the collectors of the two-collector lateral bipolar magnetotransistor of npn-type with the base, formed in the well being the third collector (3KBMTBW) at the reduced rate of the surface recombination in the base, have been experimentally investigated. The magnetotransistor switch-on circuit determines the operation mode and the device parameters. It has been shown, that the magnetosensitivity of voltage achieves 11 V/T.

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The breadboard model of a mechatronic device microsystem with the magnetotransistor transducers has been experimentally investigated. It has been determined that the microsystem of a mechatronic device with a silicon console, a micromagnet and a magnetotransistor transducer permits to control the micromovings by change of the magnetic field at resonant frequencies of the console with a micromagnet. The proposed microsystem allows receiving a magnetic signal of micromovings and vibration in the mechatronic systems and can be realized in the integrated performance.

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The investigation of the SRH-recombination in the bulk of the lateral bipolar magnetosensitive transistor with the diffusion well has been performed by the modern two-dimensional TCAD. It has been shown that when selecting specific parameters of the well and the work mode with the identical potential on the substrate and the well, in the bulk the streams of electrons and holes for recombination are formed. The bulk concentration-recombination mechanism of the current negative magnetosensitivity under the magnetic field effect upon these streams has been demonstrated.

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The results of the study on the parameters of permalloy films, produced by the electrochemical deposition in the local areas, limited by the photoresist mask on metallic surface of silicon wafer, have been presented. The experimental dependencies of magnetic parameters of the deposited permalloy on the electrolyte excerpt time have been obtained. The possibility of application of the deposited films as the magnetic field screens of the digital isolators with galvanic separation on the basis of magnetic nanostructures has been shown.

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It has been found that the relative current sensitivity of the current dual-collector lateral bipolar magnetotransistor is determined by the layout of electrodes, the dopant distribution in well (also the base of BMT), the circuit of switching-on with the general potential of the basis and substrate, an operation mode near to saturation, the value of collectors load resistance.

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The results of the study on the local electrochemical deposition from chloride electrolyte have been presented and the permalloy films NiFe with magnetic properties, similar to 3-d models with the uniform thickness and with low mechanical stresses without high-temperature annealing have been obtained. The dependencies of the congruent deposition velocity on the current density have been presented. The peralloy films are designed to enhance the magnetic field in the magneto-semiconductor microsystems.

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