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Micro-electromechanical systems (MEMS)-based devices comprise suspended structures. A sacrificial layer is required to realize these structures. Usually, metal and dielectric materials are used as sacrificial layer materials. Metallic sacrificial material has a selectivity problem, whereas dielectric materials require higher deposition temperatures. Hence, in the present paper, photoresist (PR) material is used as the sacrificial layer. PR requires low-temperature processing and has no selectivity issues. Hence, photoresists are preferred as sacrificial layer materials. In the CMOS fabrication process, thin photoresists such as S1818, S1813, and AZ1505 are used. In these photoresists, the processing wafers are placed in a vertical position during patterning, which occupies less space. The recipes of such photoresists are well optimized for a uniform thickness across the wafer. However, special thick photoresists are used as a sacrificial layer for MEMS devices. These thick photoresists reflow in the vertical position and lead to non-uniform thickness; consequently, the yield is decreased. This paper has optimized a special thick photoresist (HiPR 6517) for RF MEMS SPST switches for better yield and uniformity. The measured pull-in voltage and the switch's resonant frequency are 13.00 V and 12.32 kHz, respectively. The fabricated switch offers isolation and insertion loss better than − 35 dB and − 1 dB at 24.5 GHz, respectively. [ABSTRACT FROM AUTHOR]

In this review, we present one of the main areas of the work of the Laboratory of Physical Chemistry of Supramolecular Systems, Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, devoted to studying monolayers and ultrathin films on liquid and solid surfaces. Numerous problems are discussed concerning the peculiarities of the supramolecular organization, behavior, and functional potential of these traditional colloidal systems. The article describes diverse examples of systems that form ultrathin organized films at different interfaces and the processes occurring in them, thereby reflecting the contemporary stage of the interconnection of related fields of science (colloid and supramolecular chemistry, nanotechnology, biomimetics, sensorics, etc.). Such a combination makes it possible to develop new intelligent nanostructured devices. Complexation in ultrathin layers of ligands on liquid and solid substrates is considered in connection with the use thereof as sensitive sensory elements in systems with reduced dimensionality. Substantial attention is focused on the aggregation behavior of diverse ligands and topochemical reactions in organized 2D ensembles, development of new methods for preparing two-dimensional organic networks, and creation of highly stable supramolecular devices based thereon. In the light of the features of 2D systems, several types of mechanochemical transformations occurring under the action of two-dimensional compression–expansion are considered: the phenomenon of redox isomerism in monolayers of lanthanide bis-phthalocyaninates, the phenomenon of forced axial coordination in tetrapyrrole complexes of nickel with a change in its spin number, and the phenomenon of the reversible formation of excimers. Especial attention is given to the problems concerning the behavior of organic photochromes at interfaces and the perspectives of developing molecular switches based on photosensitive compounds. [ABSTRACT FROM AUTHOR]