**1. Introduction**

Lithography is one of the key technological processes in the production of semiconductor integrated circuits, storage devices, and precision devices for optics and micromechanics. Laser lithography, near-field, and probe technologies, and radiation exposure methods are widely used to create nanoscale structures [1, 2]. Among the methods of obtaining nanoscale structures, it is necessary to note laser lithography, which allows to carry out mask less image formation in the photoresist layer on the surface of the substrate with a laser beam. Research in the development and manufacture of nanostructures for various purposes is largely determined by the level of development of technologies that allow atomic accuracy to obtain nanostructures of

the required configuration and dimension, as well as a comprehensive diagnosis of the properties of nanostructures. Modern methods of nanoscale optical recording are based on the use of various methods, including photoinitiation with high beam intensity. A significant limitation on the size of the elements is due to the ability to focus optical radiation to sizes smaller than the diffraction limit. Many technical solutions are proposed and developed to realize the possibilities of optical nanolithography [1–3]. Special photosensitive materials can be used to form nanosized structures with focused laser radiation. Direct optical lithography can be created without the use of organic photoresists of functional inorganic nanomaterials. The ability to directly pattern completely inorganic layers using a radiation dose comparable to that of organic photoresists provides an alternative method for producing thin-film devices [4, 5]. Among these materials should be noted inorganic resist based on films of chalcogenide glassy semiconductors (CVS). Inorganic resists based on CVS films can be effectively used in the creation of micro- and nanoelements of optoelectronic devices, micro- and nanoelectromechanical systems (MEMS/NEMS), and diffractive optical elements. The use of these materials is based mainly on their sensitivity to different types of radiation, which cause phase and structural changes in CVS films, and transparency in the infrared range [4, 6–9]. Numerous studies have been conducted aimed at studying the processes of formation of nanostructures on CVS films [7, 9–12]. A number of photoinduced changes are observed in CVS, which are associated with structural transformations, phase transitions, defect formation, and atomic diffusion [6–8]. It is important to determine technologies for the formation of micro- and nanoscale structures on CVS films, which can be used in the creation of diffractive optical elements for optoelectronic devices.

Photoinduced transformations in CVS have been widely used in the optical recording of information to create optical media of various types. This is largely because the properties of thin chalcogenide films allow recording at high speed and do not impose restrictions on the minimum size of the recorded elements and, consequently, on the density of information recording [7, 12]. Numerous theoretical and experimental studies of the interaction of electromagnetic radiation and particle fluxes with CVS have shown the possibility of achieving ultra-high resolution when exposed to optical radiation or electron beam [10, 11, 13, 14]. It is shown that the resolution of an inorganic resist based on CVS is determined by the size of the structural units that form the matrix of films and is 1–2 nm [10, 13, 14]. In this regard, CVS are promising materials for the formation of nanoscale structures on their surface and the creation of ultra-dense information recording devices [1]. Numerous experiments on the exposure of thin films of CVS and their subsequent selective chemical etching have shown that when using immersion optical systems, it is possible to record microrelief structures with submicron dimensions (120–150 nm). With electron beam exposure of chalcogenide films, it is possible to form structures with sizes of 50–70 nm [1, 7]. Particular attention was paid to the choice of CVS that do not contain highly toxic elements, modes of their heat treatment and selective chemical etching [15].
