Use of an etching solution for etching both a tungsten-containing metal and a TiN-containing material from a microelectronic device, wherein the tungsten-containing metal is tungsten metal or an alloy comprising tungsten at at least 70% by weight, wherein the TiN-containing material is a layer, the majority of which is TiN, and wherein the etching solution comprises: water; oxidizers, wherein the oxidizers comprise phosphoric acid and nitric acid, wherein the phosphoric acid is present in the etching solution in an amount that is less than the amount of nitric acid, and wherein the total amount of the oxidizers is 0.5 to 60 % by weight of the etching solution; 0.01 to 20 % by weight of the etching solution of one or more fluorine-containing-etching compounds selected from ammonium fluoride, ammonium bifluoride, quaternary ammonium fluorides, HF, tetrafluoroboric acid, hexafluorosilicic acid, tetrabutylammonium tetrafluoroborate, H 2 ZrF 6, H 2 TiF 6, HPF 6, ammonium hexafluorosilicate, ammonium hexafluorotitanate, and mixtures thereof; and 0.000001 to 5 % by weight of the etching solution of one or more corrosion inhibitors wherein said one or more corrosion inhibitors are selected from aromatic hydroxyl compounds, phenolic derivatives with at least the two hydroxyl groups, acetylenic alcohols, carboxyl group-containing organic compounds and anhydrides thereof, triazole compounds, D-fructose, L-ascorbic acid, vanillin, salicylic acid, diethyl hydroxylamine, amines, alkanolamines, heterocylic amines, polyethyleneimines, morpholines, piperazines, and mixtures thereof; wherein the etching solution has a pH of less than 7; wherein the tungsten-containing metal etch rate is greater than the TiN-containing material etch rate; and wherein TiN-containing material and the tungsten-containing metal are etched at etch rates of from 1·10 -10 to 4·10 -8 m/min (1 to 400 A/min) at 25°C. water; oxidizers, wherein the oxidizers comprise phosphoric acid and nitric acid, wherein the phosphoric acid is present in the etching solution in an amount that is less than the amount of nitric acid, and wherein the total amount of the oxidizers is 0.5 to 60 % by weight of the etching solution; 0.01 to 20 % by weight of the etching solution of one or more fluorine-containing-etching compounds selected from ammonium fluoride, ammonium bifluoride, quaternary ammonium fluorides, HF, tetrafluoroboric acid, hexafluorosilicic acid, tetrabutylammonium tetrafluoroborate, H 2 ZrF 6, H 2 TiF 6, HPF 6, ammonium hexafluorosilicate, ammonium hexafluorotitanate, and mixtures thereof; and 0.000001 to 5 % by weight of the etching solution of one or more corrosion inhibitors wherein said one or more corrosion inhibitors are selected from aromatic hydroxyl compounds, phenolic derivatives with at least the two hydroxyl groups, acetylenic alcohols, carboxyl group-containing organic compounds and anhydrides thereof, triazole compounds, D-fructose, L-ascorbic acid, vanillin, salicylic acid, diethyl hydroxylamine, amines, alkanolamines, heterocylic amines, polyethyleneimines, morpholines, piperazines, and mixtures thereof; wherein the etching solution has a pH of less than 7; wherein the tungsten-containing metal etch rate is greater than the TiN-containing material etch rate; and wherein TiN-containing material and the tungsten-containing metal are etched at etch rates of from 1·10 -10 to 4·10 -8 m/min (1 to 400 A/min) at 25°C. wherein the tungsten-containing metal etch rate is greater than the TiN-containing material etch rate; and wherein TiN-containing material and the tungsten-containing metal are etched at etch rates of from 1·10 -10 to 4·10 -8 m/min (1 to 400 A/min) at 25°C.