A composition for selectively removing TiN x O y, where x = 0 to 1.3 and y = 0 to 2, from a semiconductor device comprising TiN x O y and a second material selected from the group consisting of Cu, W, low-k dielectric material, and combinations thereof, the composition comprising: a weakly coordinating anion having negative charge highly dispersed throughout its structure, which is present in a range of 1 to 10 wt% and is selected from the group consisting of hexafluorosilicate, hexafluorotitanate, tetrafluoroborate, hexafluorophosphate, hexafluoroantimonate and combinations thereof; an amine salt buffer present in a range of 0.5 to 10 wt%, which is selected from the group consisting of: ammonium chloride; ammonium bisulfate; ammonium phosphates; ammonium oxalate; ammonium perfluorosulfonates; ammonium salts of organic acid selected from ammonium citrate, ammonium acetate, ammonium lactate; and combinations thereof; wherein the ammonium having a form of N(R 1 R 2 R 3 R 4) +; wherein R 1,R 2, R 3,R 4 is independently selected from the group consisting of H, CH 3, C 2 H 5, and C 3 H 7; a non-oxidizing trace metal ion present in an amount of less than 500 ppm, and selected from the group consisting of Fe ion, Cu ion, Cu ion, Co ion, Cr ion, Mn ion and Ni ion; a non-ambient trace oxidizer, which is present in a range of 5-200 ppm, and is selected from the group consisting of Fe compounds, Ce, Vanadium, Mn(V, VI or VII) compounds, Cr(V or VI) compounds, CI(I, III or V) compounds, Br(I or III) compounds, and combinations thereof; and water; wherein the composition is hydrogen peroxide-free; the composition is exposed to air and the non-oxidizing trace metal ion in the presence of air is able to serve to catalyze the action of air as an oxidant; the composition has a pH < 4; and the composition offers a removal selectivity of TiN x O y vs. the second material > 1:1. a weakly coordinating anion having negative charge highly dispersed throughout its structure, which is present in a range of 1 to 10 wt% and is selected from the group consisting of hexafluorosilicate, hexafluorotitanate, tetrafluoroborate, hexafluorophosphate, hexafluoroantimonate and combinations thereof; an amine salt buffer present in a range of 0.5 to 10 wt%, which is selected from the group consisting of: ammonium chloride; ammonium bisulfate; ammonium phosphates; ammonium oxalate; ammonium perfluorosulfonates; ammonium salts of organic acid selected from ammonium citrate, ammonium acetate, ammonium lactate; and combinations thereof; wherein the ammonium having a form of N(R 1 R 2 R 3 R 4) +; wherein R 1,R 2, R 3,R 4 is independently selected from the group consisting of H, CH 3, C 2 H 5, and C 3 H 7; a non-oxidizing trace metal ion present in an amount of less than 500 ppm, and selected from the group consisting of Fe ion, Cu ion, Cu ion, Co ion, Cr ion, Mn ion and Ni ion; a non-ambient trace oxidizer, which is present in a range of 5-200 ppm, and is selected from the group consisting of Fe compounds, Ce, Vanadium, Mn(V, VI or VII) compounds, Cr(V or VI) compounds, CI(I, III or V) compounds, Br(I or III) compounds, and combinations thereof; and water; wherein the composition is hydrogen peroxide-free; the composition is exposed to air and the non-oxidizing trace metal ion in the presence of air is able to serve to catalyze the action of air as an oxidant; the composition has a pH < 4; and the composition offers a removal selectivity of TiN x O y vs. the second material > 1:1. ammonium chloride; ammonium bisulfate; ammonium phosphates; ammonium oxalate; ammonium perfluorosulfonates; ammonium salts of organic acid selected from ammonium citrate, ammonium acetate, ammonium lactate; and combinations thereof; wherein the ammonium having a form of N(R 1 R 2 R 3 R 4) +; wherein R 1,R 2, R 3,R 4 is independently selected from the group consisting of H, CH 3, C 2 H 5, and C 3 H 7; a non-oxidizing trace metal ion present in an amount of less than 500 ppm, and selected from the group consisting of Fe ion, Cu ion, Cu ion, Co ion, Cr ion, Mn ion and Ni ion; a non-ambient trace oxidizer, which is present in a range of 5-200 ppm, and is selected from the group consisting of Fe compounds, Ce, Vanadium, Mn(V, VI or VII) compounds, Cr(V or VI) compounds, CI(I, III or V) compounds, Br(I or III) compounds, and combinations thereof; and water; wherein the composition is hydrogen peroxide-free; the composition is exposed to air and the non-oxidizing trace metal ion in the presence of air is able to serve to catalyze the action of air as an oxidant; the composition has a pH < 4; and the composition offers a removal selectivity of TiN x O y vs. the second material > 1:1.