Aim. The paper aims to develop a process for treating the back side of silicon slabs and giving them a surface texture that enables good adhesion with printed metal with an even thickness and no mechanical stress, cracks or chipping. That is achieved by sandblasting slabs before contact material application. Silicon carbide (SiC) with particle size not exceeding 6 um is used as the abrasive material. Methods. The proposed method of sandblasting improves chip bonding by eliminating surface stress, formation of microcracks and crystal grain within the chip. The research was conducted using a sandblaster and electronic microscope. Results. It was shown that, after sandblasting, metal coating in the process of transistor collector area contact delineation improves the adhesion of the substrate semiconductor. Additionally, no mechanical stress was observes as compared to grinding, polishing and chemical treatment that are normally done before transistor contact encapsulation. Conclusions. The process of thin metal film evaporation as part of semiconductor-based device manufacture affects their dependability. The treatment and preparation of the back side of the silicon slab with finished transistor configurations is one of the key operations as part of transistor manufacturing process that affects the adhesive properties of the surface before evaporation, output characteristics of the semiconductor-based devices, yield and cost.

Технология формирования наноразмерных пленок (SiC

The paper discusses the possibility of using resonant ultrasound spectroscopy (RUS) as a source of information for the physics and technology of obtaining silicon carbide ceramics using the example of samples of SiC–25% AlN composition obtained by the method of spark plasma sintering. The possibility of obtaining a complete set of elastic moduli (EM) of samples with an error of less than 1% is shown. At the same time, the requirements for surface quality are significantly reduced. The revealed functional relationship between EM and porosity allows creating a non-destructive method for porosity control and calculating the elastic moduli at zero porosity (i.e., the elastic modulus of the ceramic matrix EM0). Comparison of EM0 samples obtained at different parameters of the technological process allows determining their optimal values.

The main advantages of spark plasma sintering (SPS) method compared to the classical hot pressing method for obtaining high-density ceramic based on silicon carbide are presented. Shows the perspective of obtaining a wide range of materials using this method. The possibilities of technology of spark plasma sintering of multicomponent ceramics based on silicon carbide of different composition have been studied. Established optimal SPS modes for sintering multicomponent ceramics of composition SiC (75%) - 22% (AlN) -Y2O3 (3%) (1800 °C/50MPa/15 min) provide formation of 100% dense composite, which allows to recommend these modes for making light and high-density ceramic material of specified composition with predicted properties.

High-density ceramic based on silicon carbide with the addition of beryllium oxide compositions (1-2)% wt. With a step of 0.2 was obtained. X-ray diffraction studies of SiC-BeO ceramics showed changes in the lattice parameter of SiC “c” with the addition of beryllium oxide, the minimum value of which was observed for a composition of 1.4% wt. BeO. For compositions greater than 1.4% wt. BeO was observed only polytype 6H. The grain size of sintered ceramic materials reached up to 20 microns. The elastic moduli, microhardness, and shear strength for hot-pressed SiC-BeO ceramic materials are determined.

The structure and thermal diffusivity of SiC - NbC ceramic materials are investigated. It is shown that with a change in the composition in sintered ceramics, the lattice parameter changes, and also in the near-contact region there is a mutual diffusion of silicon and niobium. This indicates the formation of solid solutions. As the niobium carbide content and temperature increase, the thermal diffusivity of SiC - NbC ceramic materials decreases.

The article is devoted to the establishment of regularities of synthesis and technological aspects of the formation of composite ceramics based on silicon carbide and aluminum nitride by the method of hot pressing, as well as the study of its structural properties. The paper presents the results of the study of the microstructure and elastic properties of ceramics based on silicon carbide, obtained by hot pressing at temperatures up to 2170 K and pressures up to 35 MPa, of various compositions (0.9SiC - 0.1AlN; 0.7SiC - 0.3AlN; 0.5SiC - 0.5AlN; 0.3SiC - 0.7AlN; 0.1SiC - 0.9AlN), the average density of which is 3.21 g/cm(3). The microstructure of the obtained samples was studied with a scanning electron microscopy. Elastic moduli of SiC-AlN hot-pressed ceramic materials were determined by the method of resonant ultrasonic spectroscopy (RUS) depending on the composition. Our data on Poisson's ratio are in good agreement with the literature data and are well described by linear approximation. The values of Young's modulus are noticeably lower than the literature ones. The values of the elastic moduli lie below the additive right line of ceramic SiC and AlN with zero porosity, which is related to the influence of the porosity of our samples.

Разработана технология получения высокоплотной керамики на основе карбида кремния с добавками оксида бериллия составов (1-2 % мас.) с шагом 0,2.Плотность керамических материалов на основе карбида кремния достигала до 90 % от теор.плот.Керамика получена методом горячего прессования при температуре 2420 К, в среде азота, в течение 1 часа, при давлении прессования до 35 МПа, предварительно активированных механоактивацией порошков карбида кремния и оксида бериллия.Рентгеноструктурные исследования керамики SiC-BeO показали изменения параметра решетки SiC с добавлением оксида бериллия, минимальное значение которого наблюдалось для состава 1,4 % мас.BeO.Для составов больше 1,4 % мас.BeO наблюдался только гексоганальный политип 6Н.Размер зерна спеченных керамических материалов достигал 20 мкм.Определены упругие модули для горячепрессованных керамических материалов SiC-BeO.Установлено, что значения модуля Юнга керамических материалов SiC-BeO удовлетворительно ложатся на единую регрессионную кривую зависимости от пористости азотированных керамических карбидокремниевых материалов.

Experimental measurements of the effect high pressure and temperature have on the thermal conductivity of silicon carbide SiC–BeO ceramics are presented. The pressure is varied in an interval of up to 400MPa; temperature, in the range of 273–523 K. The results reveal there is a reversible second-order phase transition at pressures of 100–150 MPa.

This study describes the principles of synthesis and technological features of composition ceramics formation on the basis of silicon carbide and aluminum nitride by hot-pressing. The structural properties and composition of the ceramics were investigated by scanning electron microscope and the formation of the solid solution is confirmed. The elements distribution on the surface of failure pattern is shown. The results of the study are useful for optimization of manufacturing process of structural and functional high-density ceramics.

A process for ion-plasma formation of aluminum nitride (AlN) nanolayers on nitrided sapphire (Al2O3) substrates is presented. The method is based on the direct current magnetron sputtering of a high-purity aluminum target in the presence of an argon–nitrogen gas mix and high frequency-activated nitrogen plasma. The method, combined with ion etching, produced matched layers by nitration of Al2O3 in the (0001) plane, and formation of high quality AlN epilayers on this surface was observed. The processing characteristics and morphology dependence on synthesis parameters were studied using atomic force microscopy.

В настоящее время актуальными являются исследования, направленные на получение твердых растворов (SiC)x(AlN)1-x в системе используемых в качестве мишеней для получения тонких пленок (SiC)x(AlN)1-x методами ионно-плазменного распыления. Работа посвящена исследованию структурных свойств горячепрессованной керамики на основе SiC-AlN.

The temperature distribution in a growth cell and the temperature gradient in the melt zone during the electric-field liquid phase epitaxy of silicon carbide based solid solutions (ytterbium-gallium, ytterbium-aluminum) were calculated with an allowance for the growth cell geometry. The analysis was based on a solution of the stationary thermal conductivity equations in all five regions of the standard growth cell. The solution was obtained taking into account the following factors: (i) Joule’s heating; (ii) Peltier’s heating (cooling) at the electrode-source (substrate)-melt zone interfaces; (iii) contact heat liberated at the electrode-source (substrate) interface; (iv) dissolution heat; and (v) crystallization heat. Expressions for the temperature gradient ∇T in the melt zone as a function of the current density and the dimensions of regions in the growth cell are obtained.