Kinetic Regularities of Etching Thin Lead Sulfide Films in Hydrochloric Acid Solutions Containing Hydrogen Peroxide and

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GANIC SYNTHESIS AND INDUSTRIAL INORGANIC CHEMISTRY

Kinetic Regularities of Etching Thin Lead Sulfide Films in Hydrochloric Acid Solutions Containing Hydrogen Peroxide and Glycerol M. S. Rogovoia,*, S. S. Tulenina, and D. A. Novotorkinaa a

Ural Federal University named after the first President of Russia B. N. Yeltsin, Yekaterinburg, 620002 Russia *e-mail: [email protected] Received February 29, 2020; revised April 1, 2020; accepted April 22, 2020

Abstract—The kinetic regularities are considered of etching thin films of lead sulfide in solutions containing hydrochloric acid, hydrogen peroxide, and glycerol under conditions of varying concentrations of the initial components and the etching temperature. The partial orders of the reaction were calculated: for hydrochloric acid the value was 2.8, for hydrogen peroxide, 0.2, and for glycerol, 0.5. The activation energy of the lead sulfide etching process was 48.1 kJ mol–1.

Keywords: etching, semiconductor, thin films, lead sulfide, hydrochloric acid DOI: 10.1134/S1070427220100079

The method of liquid chemical etching is widely used in the manufacture of microelectronic devices and is characterized by low sensitivity to defects on the surface of the material, as well as the ability to control changes in temperature and concentration of the etching solution [1]. Solutions based on mineral acids containing strong oxidizers and substances that increase the viscosity of the etching solution are used as etchants for semiconductor structures [2, 3]. The photoelectric and operational characteristics of the sensitive elements of semiconductor detectors, as well as the reproducibility of their properties, largely depend on the composition of the etching solution and the process conditions. In microelectronics, among semiconductor compounds, lead sulfide is a widely used material for the creation of sensitive elements of visible and IR radiation in the range of 0.4–3.5 μm by photolithography using local liquid etching. Poor knowledge of the process of local etching of lead sulfide can lead to a deterioration in the characteristics of the obtained elements, reduce the reproducibility of their geometric dimensions and the yield of suitable products. In the literature, only the issues of selective and polishing etching of PbS single crystals are considered [4]; however, there are no data

on local etching of polycrystalline lead sulfide films in order to form the topology of sensitive elements and the results of kinetic studies of the PbS etching process. The purpose of the work is to study the kinetic regularities of the etching process of chemically deposited thin PbS films in solutions containing hydrochloric acid, hydrogen peroxide, and glycerol for subsequent optimization of the conditions for the formation of the topology of elements in the process of photolithography. EXPERIMENTAL For the study, thin-film layers of lead sulfide PbS with a thickness from 650 to 1000 nm were synthesized under thermostated conditions at 353 K for 90 min from a reaction mixture containing lead acetate P