Lateral outward growth of single-crystal diamond by two different structures of microwave plasma reactors

On a semi-open holder, the homoepitaxial lateral growth of single-crystal diamond (SCD) was carried out via microwave plasma chemical vapor deposition (MPCVD). By tuning and optimizing two different structures of...

Methods for obtaining a dispersed structure and increasing the strength of silicon-manganese steels

For high-strength structural steels, the problem of grinding grain and increasing strength is solved by the use of highly efficient technologies, the development of new steel compositions and the development of rational thermomechanical processing. Goal. The aim of the work is to transform the structure, study the methods of grain grinding and increase the strength properties of structural steels 09Г2, 09Г2С as a result of modification by nanodisperse compositions, heat treatment and intense plastic deformation. Methodology. The research material was structural low-carbon steels 09G2, 09G2S. The process of modifying the steel parameters of the geometric shape of the melts was carried out by smelting steels 09G2 and 09G2C in an induction furnace. The modified workpieces were subjected to intensive plastic deformation and heat-treating treatment according to the mode: heating temperature 1050 °C, exposure 5 min; cooled medium: water and 20 % solution of NaCl in water. Then – a rest at temperatures of 500 °C; 600 °C, exposure time – 30 minutes. Metallographic studies of the structure of steels before and after modification and mechanical testing of standard samples were performed. Results. The study of the structure grains of steels 09Г2 and 09Г2С in the initial state showed the presence of large grains up to 30 μm, reduced microhardness and yield strength. Originality. The substantiation of the choice of type and fraction of nanodisperse modifier was carried out. The use of plasma-chemical synthesis to obtain nanopowders based on titanium was substantiated. Nanopowders of titanium carbonitride Ti (CN) fraction 50 ... 100 nm were obtained by the method of plasma chemical synthesis. Practical value. The following methods were proposed for grinding grain and increasing the strength properties of steels: nanomodification, intensive plastic deformation in combination with heat-strengthening treatment.

Influence of nanomodication on structure for-mation and properties of structural steel

The state of the problem of grinding the grain structure and improving the mechanical properties of low-alloy structural steels has been studied. The state of the problem of grain structure refinement and improving the mechanical properties of low-alloy structural steels has been studied. The role of nanodispersed additives is reduced to the creation of additional artificial crystallization centers in the melt. They must be consistent with the critical radiuses of the embryos. According to our calculations, for the grinding of primary austenite grains in castings, the size of the introduced particles should be 40–50 nm. Output and modified castings of 09G2 and 09G2S steels were subjected to severe plastic deformation by equal-channel angular pressing followed by low-temperature annealing at 350 °C. In the initial state, cast steels 09G2 and 09G2S had a ferrite-pearlite structure with an average primary austenite grain size of 30 μm; after modification and deformation, the grain size was 10 μm. After quenching and cooling in water, the structure has changed insignificantly - ferritic-reed, with an average grain size of ~ 8...10 microns. After cooling the quenched samples in a solution of 20 % NaCl in water, the structure of packet martensite was obtained. In the initial state, the studied steels have insufficiently high property values: microhardness Нμ up to 3000 MPa, yield point σ 0,2 up to 800 MPa. When quenching in water, the hardness somewhat increases, the most significant increase is observed when the samples are cooled in a NaCl solution. Due to the significant grinding of martensite crystals, accelerated cooling provides a greater increase in hardness. A nanodispersed powder of titanium carbonitride Ti (CN) with a fraction of 50...100 nm was obtained by the method of plasma-chemical synthesis, the process technology was developed. Intensive plastic deformation of 09G2 and 09G2S steel castings was carried out. The structure and properties of steels before and after treatments have been studied. As a result of the combination of hardening methods, the grain size of the steels was reduced by 3 times and the yield strength increased from 3000 to 4000 MPa. Nanodispersed powder of titanium carbonitride Ti (CN) with a fraction of 50...100 nm was obtained by the method of plasma chemical synthesis, and a process technology was developed. Intensive plastic deformation of castings of 09G2 and 09G2S steels was carried out. The structure and properties of steels before and after treatments were studied. As a result of a combination of hardening methods, grinding of steel grains by 3 times and increasing the yield strength from 3000 to 4000 MPa was achieved

EFFECT OF PASSIVATING COATINGS ON METALLIZATION TOPOLOGY IN PRODUCTION OF SEMICONDUCTOR DEVICES

The surface quality of the metallized contact pads on the crystal plays an important role in the production of semiconductor devices. This paper presents experimental studies of the effect of a protective passivation film of silicon oxide on the surface structure of aluminum metallization in the field of forming contact pads. Plasma chemical deposition of passivation layer SiO2 from gas phase (PECVD method) was carried out on prepared samples of silicon with aluminum metallization using a high-frequency power source with a frequency of 13.56 MHz. After that, chemical etching of precipitated silicon oxide was carried out to simulate the process of forming contact areas of semiconductor device crystals. The resistance of the metallization surface to plasma processes was studied by raster electron microscopy. It is shown that as a result of the process cycle, defects of the dislocation type are generated in the applied film Al. The nature of the observed defects has been found to be different. The revealed large square-shaped pits with a size of ~ 1 μm at the places where dislocations come to the surface are of a single nature and appear independently of the processes of applying passivation coatings, which is determined by the orienting action of a single-crystal substrate having some low dislocation density. While the second type of defects, shown by the presence of etching pits measuring ~ 100-300 nm, is characterized by a higher surface density. Moreover, the exclusion of the passivation process with silicon oxide did not lead to the appearance of this type of defects, which determined their nature associated with the ion bombardment of the Al layer during the plasma chemical deposition of silicon oxide from the gas phase. It is also shown that a feature of this type of defects is their disorientation both with respect to the first type of defects and with respect to each other. Detection of the structure of the metallization layers was carried out by X-ray diffraction, the results of which show the polycrystallinity of the formed aluminum metallization. The preferred orientation of the aluminum film corresponds to the substrate Si (111).

Self-consistent modeling of microwave activated N2/CH4/H2 (and N2/H2) plasmas relevant to diamond chemical vapour deposition

The growth rate of diamond by chemical vapour deposition (CVD) from microwave (MW) plasma activated CH4/H2 gas mixtures can be significantly enhanced by adding trace quantities of N2 to the process gas mixture. Reasons for this increase remain unclear. The present article reports new, self-consistent two-dimensional modelling of MW activated N2/H2 and N2/CH4/H2 plasmas operating at pressures and powers relevant to contemporary diamond CVD, the results of which are compared and tensioned against available experimental data. The enhanced N/C/H plasma chemical modelling reveals the very limited reactivity of N2 under typical processing conditions and the dominance of N atoms amongst the dilute ‘soup’ of potentially reactive N-containing species incident on the growing diamond surface. Ways in which these various N-containing species may enhance growth rates are also discussed.

Plasma surface treatment of local modify silicon plates

This paper presents a study of the use of silicon Si for element base manufacture of micro- and nanoelectronics by using combined methods of focused ion beams and atomic layer plasma chemical etching. This technology makes it possible to modify surface of Si substrates in the required topology and geometry, followed by removal of atoms to obtain nanoscale elements. The influence of parameters of method of focused ion beams and plasma chemical etching on parameters of the formed structures is analyzed. So, for example, for formation of structures with maximum roughness, it is necessary to increase values of parameters responsible for reactive ion etching, these are such parameters as: the power of capacitive plasma source, the mixing voltage, and the flow rate of an inert gas (argon).

Metallurgical silicon refining using electron-beam plasma

The possibilities of plasma-chemical refining of metallurgical silicon have been demonstrated. It is shown that by electron-beam refining it is possible to reduce the concentration of phosphorus and boron, as well as the main metallic impurities by evaporation of both these impurities and their volatile compounds.