The paper presents the design features of silicon microprobe with a cross-sectional size less than 100 μm, taking into account the number of electrodes, as well as the conditions of anisotropic wet etching. Analytical calculations were carried out for the probe structure, represented by n-regions of various widths, carrying up to 2n-1 electrodes. The dependences of bottom width of the trapezoidal section of the probe and width of related mask on the thickness and top width of the probe are obtained. The permissible dimension ranges for several cases of one- to four-level microprobes have been established. The correction value of the mask size was estimated, reflecting the effect of etching conditions on the geometry of the probe. Modeling was carried out in an anisotropic wet etching simulator taking into account the conditions of KOH etching (in 20-40% solution at 60-80°C). It allowed to refine the results of the analytical calculations, refine dimensions of the silicon microprobe structure, the geometry of related masks, as well as the extent undercutting effect. The obtained results could be used in development of silicon microprobes formed by anisotropic wet etching.
In recent years, aluminum oxide films have found application in surface acoustic wave sensors. The paper presents the mechanical and physical properties of aluminum oxide (Al2O3) films obtained by the sol-gel method and subsequent sintering by high-temperature annealing. The synthesis of an aluminum oxide film from inorganic sols using the sol-gel technology was carried out. The effect of high-temperature treatment on the geometric dimensions, surface morphology, and hardness of Al2O3 films has been investigated. It was found that due to high-temperature sintering, the average values of film thickness and surface roughness are reduced by about 2 times. The effect of sintering temperatures on hardness suggests that with increasing temperature hardness of aluminum oxide film increases, and at sintering temperature of 800°C was 11.7±1.2 GPa.
The article presents the results of designing, manufacturing, and studying the resonant properties of a square silicon membrane for use in a fiber-optic acoustic receiver. The dependences of resonant frequency on edge length (6-9 mm) and thickness of the membrane (30-50 μm) are obtained. The geometrical parameters of the membrane satisfying the values of resonant frequency (2-60 kHz), pressure (0.1-14 Pa), and deviation (10 nm) are determined: edge length is 8 mm and thickness is 40-50 μm (9.2-42.3 kHz). A series of square silicon membranes was fabricated by anisotropic wet etching. The amplitude-frequency characteristics of the membranes were experimentally measured using an adaptive holographic interferometer. For a square membrane of 8×8×0.044 m3, the experimentally measured resonant frequency was 10.1 kHz, which is consistent with the results of numerical simulation.
A sol-gel synthesis of alumina-based films and followed single crystal formation by thermal fields in vacuum are investigated that can be applied as gate dielectrics for organic field-effect transistors. The results showed that the values of roughness and thickness of the sol-gel Al2O3 film decreased by almost 2 times with increasing temperature annealing in vacuum. It is established that the dielectric constant of sol-gel films decreasing from 9.1 to 7.3 through vacuum annealing at 1000°C acquiring typical value of crystalline sapphire.
The paper presents the technology of forming a nanocomposite based on an array of vertically oriented carbon nanotubes and polycrystalline silicon. The material could be used in fabrication of inertial microelectromechanical system with high aspect ratio structure. Carbon nanotube arrays were grown and coated with a layer of polycrystalline silicon using plasma enhanced chemical vapor deposition. The purpose of the study is to determine experimental conditions for obtaining the nanocomposite with a minimum number of pores in the bulk. The deposition features of the nanocomposite with an intertube distance from 50 to 200 nm are determined. A test array of carbon nanorods (2.5μm in height, aspect ratio ~14) instead of nanotubes is formed for a quantitative analysis in the range of interrod spacing from 500 to 2000 nm. The average deposition rate of silicon at 600°C and 10 W was 15 nm/min on a substrate and 7-8 nm/min along the sidewalls.
In this paper we investigated a planar field emission cell with a multiemitter cathode. Multilayer graphene on silicon carbide was used as the material of the field emission cell. The simulation of the electric field distribution in the nanoscale interelectrode gap of the field emission cell was carried out. The use of a planar multiemitter cathode on a flat base leads to inhomogeneity of the electric field strength at the tops of the tips. The electric field strength at the tops increases in the direction from the center to the edge. A design with a disk anode and a surrounding multiemitter cathode is proposed. The uniform distribution of the tips along the perimeter of the cathode contributed to the exclusion of the screening effect. The proposed design makes it possible to reduce the distance between the tips in the matrix cathode while maintaining the uniform electric field strength on the tops.
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