Levchenko I. Interaction between InAs, InSb, GaAs, GaSb and (NH4)2Cr2O7−HBr−solvent aqueous solutions

The features of the chemical dissolution of InAs, InSb, GaAs and GaSb crystals in the based on (NH4)2Cr2O7 bromine emerging etching compositions have been established. The component compositions of the (NH4)2Cr2O7−HBr−С6Н8О7 (20 % and 40 %), (NH4)2Cr2O7−HBr−С4Н6О6 (27 % and 40 %), (NH4)2Cr2O7−HBr−С3Н6О3, (NH4)2Cr2O7−HBr−СН2(ОН)СН2(ОН) and (NH4)2Cr2O7−HBr−Н2О etching solutions influence on the nature of mention above crystal dissolution has been defined and 28 diagrams of “solution composition – etching rate” have been constructed. Assessing the quality of obtained surface, the compositions of polishing and unpolishing solutions have been selected in the component concentration interval with (in vol.%): (2-22) (NH4)2Cr2O7:(10-98) HBr:(0-80) solvent. The influence of hydrodynamic conditions and temperature on the mechanism and a rate of substrate etching have been defined. The rotation disk method allows the controlling of the reagent interaction rate and the removing of the layer thickness. According to the results of temperature dependencies of the dissolution, the values of apparent activation energy with Еа = 1,25-23,53 kJ/mol have been calculated and the kinetic compensation dependence between the value of apparent activation energy and pre-exponential factor changing has been found. The results of the treated surface investigation by X-ray diffraction analysis and micro-Raman spectroscopy indicate that in the polishing etchants the crystal dissolution produce the clean surface. Stoichiometric ratio of [AIII]/[BV] on the crystal surfaces confirms that investigated etching compositions promote the uniform dissolution of the semiconductor elements which does not depends on their nature. The method of atomic-force microscopy confirmed the formation of the super-smooth surface with surface roughness Ra = 0,2-9,3 nm after its dissolution in the polishing etching compositions. It was shown that chemical-dynamic polishing promotes the surface roughness increasing, in comparison with chemical-mechanical polishing. The series of low-rate etching solutions (v = 0,1-10,4 μm/min) with polishing features have been developed. They provide the controlling remove of damaged layer.