**6. The formation of nanosized relief structures on films of chalcogenide vitreous semiconductors by the methods of probe microscopy**

Scanning probe lithography (SPL) is a direct-write nanolithography technique in which elements on thin films of chalcogenide semiconductors are created by scanning a sample with a sharp nanometer tip to create localized modifications. The interactions of the tip with the sample are varied and can include mechanical, electrical, diffusion, and thermal effects. SPL techniques are being studied intensively. SPL methods provide nanometer resolution, however, they are characterized by a low write speed, which is 0.1–50 μm/s [40]. The technology of nano-heating of thin-film materials with a phase transition has been studied in detail and it has been shown that it makes it possible to register ultra-small spots with sizes less than 50 nm [41].

With the use of technologies based on atomic force microscopy, the recording of data and the formation of nanosized structures on films of CVS with phase transitions were successfully executed [42]. The information recording is based on the formation of local (crystalline/amorphous) sections with different structures and, respectively, conductivities in the nanosized layer of a chalcogenide material with the help of electric pulses [42]. It was shown that, due to the applied pulses of the voltage between a probe and a conducting electrode, the conductance of a chalcogenide amorphous GeSb2Te4 film increases by at least two orders. An increase in the conductance is caused by the phase transition of a chalcogenide film from the amorphous state into a crystalline one. The recorded data are read with the probe of an AFM by the measurement of changes in the conductance of a chalcogenide film. The simultaneous measurement of the conductance and topographic images with the help of an AFM showed that the surface relief of recorded zones is invariable in the process of recording. The least recorded imprints were down to 10 nm in diameter [42].

Such technology of recording allows one to form elements with sizes of a recording zone of ~30-70 nm, which is 3-5 times less than the real diameter of focused exposing rays of laser sources of violet and ultraviolet emissions.

The creation of a relevant relief in a recording zone occurs directly during the simultaneous exposure and indentation, which presents the essential advantage over the available lithographic methods, which require the additional treatment of a carrier with selective chemical etchants or the ion-beam or plasma chemical etching. The profiles of imprints obtained at the nanoindentation of an As20Se80 film in dark and light at various loads are given in **Figure 10** [1].

One of the advantages of the given method is the absence of a thermal heating source used for the softening of the surface area that is modified and, respectively, the absence of shortcomings related to such heating (power losses, the complexity of a micromechanical system, loads, etc).

An extension of scanning probe lithography (SPL) is plasmonic nanolithography with a focused beam. This technology is promising due to its sub-diffraction resolution. In this method, the resist is scanned and illuminated by a focused light spot created by a plasmonic lens.

#### **Figure 10.**

*General view of imprints (upper row) and their profiles (lower row) obtained at the nanoindentation of an As20Se80 film in dark and in light at loads of 120-240 mN (a) and 700-900 mN (b). Scheme of application of a load (c) and the relevant curves of nanoindentation in dark (d) and in light (e) [1, 43].*
