785 ISSN 0020-1685, Inorganic Materials, 2020, Vol. 56, No. 8, pp. 785–790. © Pleiades Publishing, Ltd., 2020. Russian Text © The Author(s), 2020, published in Neorganicheskie Materialy, 2020, Vol. 56, No. 8, pp. 829–835. Chemical Polishing of Single-Crystal PbTe and Pb 1 – x Sn x Te Wafers G. P. Malanych a, *, V. N. Tomashyk a , and A. A. Korchovyi a a Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, pr. Nauki 41, Kyiv, 03028 Ukraine *e-mail: galya.malanich@gmail.com Received November 20, 2019; revised January 31, 2020; accepted March 3, 2020 Abstract—We have studied chemical–mechanical and dynamic chemical polishing of the surface of single crystals of PbTe and Pb 1 – x Sn x Te solid solutions with bromine-releasing etchants based on aqueous (H 2 O 2 + HBr + ethylene glycol)/glycerol solutions. The rates of chemical–mechanical and dynamic chemical polish- ing have been determined as functions of the dilution of the basic polishing etchant with an organic compo- nent. The composition of polishing mixtures and chemical etching conditions have been optimized using microstructural analysis of crystal surfaces, surface roughness measurements, and elemental analysis of sam- ple surfaces. Keywords: chemical etching, lead telluride, dissolution rate DOI: 10.1134/S0020168520080099 INTRODUCTION In modern semiconductor materials technology, an important role is played by surface processing and surface preparation for the fabrication of working ele- ments of devices. Special attention is paid to the preparation of surfaces as perfect in structure and geometry as possible, chemically homogeneous, and uniform in purity, which is an important condition for the ability to fabricate quality semiconductor devices. Chemical treatment of PbTe and Pb 1 – x Sn x Te crystals is a particularly important step in the fabrication of working elements of devices, because it enables the surface deformation layer produced by preceding abrasive processing to be removed and helps obtain high-purity surfaces as structurally perfect and chem- ically homogeneous as possible. These issues are suc- cessfully addressed using wet etching. The chemical polishing process has a number of drawbacks: it fails to maintain the opposite faces of wafers plane-parallel and smooth; the etching process is nonuniform and often has a selective character; and the sample surface can be covered with a film of chemical compounds insoluble during the etching process, which can be only removed by additional processing. To obviate the above-mentioned drawbacks, one should use chemical–mechanical polishing (CMP). The CMP process combines simultaneous effects of chemical and mechanical factors and can be roughly described by Preston’s equation [1, 2]. In practice, the CMP process is run on a polisher covered with soft natural or synthetic cloth, to which an etching solution or slurry consisting of an etchant and abrasive (Al 2 O 3 , SiO 2 , CeO 2 , Mn 2 O 3 , and other) particles is fed. At the same time, the use of slurries presents some difficul- ties related to the agglomeration of abrasive particles over time, which impairs the performance of the pol- ishing mixture and polishing quality. A variety of defects are typical of the CMP process with the use of slurries: polishing slurry residues, scratches, and cavi- ties. More active chemical etching of one material can lead to the formation of pits up to tens of nanometers in depth, with an uneven surface, reproducing the pic- ture made by this material on the substrate surface. Because of this, in most cases the CMP step is carried out in a polishing etchant adjusted to a particular semiconductor material. In the case of such polishing, reagents oxidize or dissolve the surface layer of wafers, and a polisher mechanically removes reaction prod- ucts and microscopic semiconductor particles. The material removal rate, surface quality, and geometric parameters of substrates strongly depend on the com- position of the polishing mixture, processing tempera- ture, pressure on the wafer, and polisher material. Since PbTe and Pb 1 – x Sn x Te crystals are character- ized by low microhardness, their mechanical process- ing (cutting, lapping, and polishing) leads to the for- mation of a disturbed layer several hundred microns in thickness [3, 4]. The removal of the disturbed layer by a polishing etchant influences the planarity of the wafer, which is very important if wafers are used as substrates for epitaxial film growth. In processing IV– VI crystals, the best results are ensured by CMP: sur- face roughness does not exceed H z = 40–60 Å, and the thickness of the surface oxide layer is 65–130 Å [5]. In view of this, in addition to abrasive processing with powder as fine as possible in the final steps, particular attention was paid to CMP because it is owing to it that