Geometry of Structures Developed by Anisotropic Etching in the Nanometer Range

Geometric disadvantages of nanostructure surface developed by anisotropic etching of silicon are discussed. These disadvantages increase uncertainness of its sizes and impeded its using as an etalons for linear measurements. The greatest uncertainness are observed for structures with trapezoid profile. They make up due to defects on sidewalls of etched structures. The surface of a sidewall is proposed to be disposed in the [111] plane and so be absolutely flat. Really parts of a sidewall surface are deflected in stepwise way from the plane [111]. This phenomenon leads to deflection of angles between converging flat sections of etched structure from its known values for silicon. Consequence of this is most drastic to a measure MShps-2K due to its structure, technology of anisotropic etching and absence of required control. Sources of these surface disadvantages induced by anisotropic etching are discussed. Possibilities to decrease disadvantages are evaluated.

Metasurface Fabrication by Cryogenic and Bosch Deep Reactive Ion Etching

The research field of metasurfaces has attracted considerable attention in recent years due to its high potential to achieve flat, ultrathin optical devices of high performance. Metasurfaces, consisting of artificial patterns of subwavelength dimensions, often require fabrication techniques with high aspect ratios (HARs). Bosch and Cryogenic methods are the best etching candidates of industrial relevance towards the fabrication of these nanostructures. In this paper, we present the fabrication of Silicon (Si) metalenses by the UV-Nanoimprint Lithography method and cryogenic Deep Reactive Ion Etching (DRIE) process and compare the results with the same structures manufactured by Bosch DRIE both in terms of technological achievements and lens efficiencies. The Cryo- and Bosch-etched lenses attain efficiencies of around 39% at wavelength λ = 1.50 µm and λ = 1.45 µm against a theoretical level of around 61% (for Si pillars on a Si substrate), respectively, and process modifications are suggested towards raising the efficiencies further. Our results indicate that some sidewall surface roughness of the Bosch DRIE is acceptable in metalense fabrication, as even significant sidewall surface roughness in a non-optimized Bosch process yields reasonable efficiency levels.

Selected Aspects of Electrochemical Micromachining Technology Development

The paper focuses on the fundamentals of electrochemical machining technology de-elopement with special attention to applications for micromachining. In this method, a material is removed during an anodic electrochemical dissolution. The method has a number of features which make it attractive technology for shaping parts with geometrical features in range of micrometres. The paper is divided into two parts. The first one covers discussion on: general characteristics of electrochemical machining, phenomena in the gap, problems resulting from scaling down the process and electrochemical micromachining processes and variants. The second part consists of synthetic overview of the authors’ research on localization of pulse electrochemical micromachining process and case studies connected with application of this method with use of universal cylindrical electrode-tool for shaping cavities in 1.4301 stainless steel. The latter application was conducted in two following variants: electrochemical contour milling and shaping carried out with sidewall surface of rotating tool. In both cases, the obtained shape is a function of electrode tool trajectory. Selection of adequate machining strategy allows to obtain desired shape and quality.

Enhancement in external quantum efficiency of AlGaInP red μ-LED using chemical solution treatment process

To investigate the effects of their surface recovery and optical properties, extremely small sized (12 µm × 12 µm mesa area) red AlGaInP micro light emitting diodes ($$\upmu$$ μ LED) were fabricated using a diluted hydrofluoric acid (HF) surface etch treatment. After the chemical treatment, the external quantum efficiencies (EQEs) of $$\upmu$$ μ -LED at low and high injection current regions have been improved by 35.48% and 12.86%, respectively. The different phenomena of EQEs have a complex relationship between the suppression of non-radiative recombination originating from the etching damage of the surface and the improvement of light extraction of the sidewalls. The constant enhancement of EQE at a high injection current it is attributed to the expansion of the active region’s sidewall surface area by the selective etching of AlInP layers. The improved EQE at a low injection current is related to the minimization of the surface recombination caused by plasma damage from the surface. High-resolution transmission electron microscopy (HR-TEM) revealed physical defects on the sidewall surface, such as plasma-induced lattice disorder and impurity contamination damage, were eliminated using chemical treatment. This study suggests that chemical surface treatment using diluted HF acid can be an effective method for enhancing the $$\upmu$$ μ -LED performance.

Design and Optimisation of Schottky Contact Integration in a 4H-SiC Trench MOSFET

Planar Schottky contact and various trench Schottky contacts have been integrated into the edge termination region of a 4H-SiC trench metal-oxide-semiconductor field-effect-transistor (MOSFET). The forward and reverse characteristics of various design splits have been benchmarked to determine the optimum method of the Schottky contact integration. As a result, the trench Schottky diode with Schottky metal contact in both the planar surface and the trench sidewall surface has been able to offer the best performance.

Etch characteristics of nanoscale ultra low-k dielectric using C3H2F6

Next generation semiconductor devices require ultra low dielectric constant (ULK) materials such as porous SiCOH on the back end of line structure for lower resistance and capacitance (RC) time delay, however, these ULK materials are easily damaged by the exposure to plasmas during the etching. In this study, etch characteristics of nanoscale TiN masked porous SiCOH such as etch rate, etch profile, surface damage, etc. and plasma characteristics by using C3H2F6 based gases have been investigated with a dual-frequency capacitively coupled plasma system (DF-CCP) and the results were compared with those by using conventional C4F8 based gases used for low-k dielectric etching. The results showed that, for the similar etch rates and etch profiles of porous SiCOH, lower sidewall damage was observed for the etching with the C3H2F6 compared to the C4F8. The analysis showed that it was related to less UV (less than 400 nm) emission and less fluorine radicals in the plasma for C3 H2F6 compared to C4F8, which leads to less fluorine diffusion to the sidewall surface of the etched porous SiCOH by the fluorine scavenging by hydrogen in C3H2F6.

Modeling drive wheels of hoisting machines with rubber cables

Upgrading of hoisting machines aims to improve their performance, to reduce risk of accidents, and to cut down operational and capital costs. One of the redesign solutions is replacement of steel cables by rubber cables. This novation can extend life of pulling members, decrease diameters of drive and guide wheels and, consequently, elements of the whole hoisting machines: rotor, reducing gear, motor. This engineering novation needs re-designing of hoisting machines; thus, the new design should be validated, in particular, strength characteristics of the machine members. This article considers a drive wheel of a hoisting machine with a pulling belt. In order to justify the potential range of design parameters with regard to safety factor, the numerical models of different-design drive wheels are developed and their operation with pulling belt (rubber cable) is simulated in the SolidWorks environment. The data on the stress state of the wheel elements are analyzed, the most loaded points are identified, and the maximal stresses on the sidewall surface and in the spokes of wheels of different designs are plotted.