Etching composition and use thereof with feedback control of HF in BEOL clean

A process for providing an aqueous back-end-of-line (BEOL) clean with feed-back control to monitor the active component of HF in the clean, for a wiring/interconnect of a reactive ion etched semiconductor device, comprising: subjecting the reactive ion etched semiconductor device to a post metal RIE clean using an etchant composition comprising about 0.01 to about 15 percent by weight of sulfuric acid; about 0.1 to about 100 ppm of a fluoride containing compound; and a member selected from the group consisting of about 0.01 to about 20 percent by weight of hydrogen peroxide or about 1 to about 30 ppm of ozone, comprising: (a) mixing water, sulfuric acid and hydrogen peroxide in a mixing tank; (b) mixing HF directly into the mixing tank or adding HF into a separate vessel for wafer processing, either before, during or after the mixture water, sulfuric acid and hydrogen peroxide as a mixture is transported to the separate tank for wafer processing; (c) taking a sample comprising HF from the mixing tank or HF from the wafer processing tank and sending the sample through a feedback loop; (d) comparing the sample to a standard dilute solution of HF to obtain a value of HF concentration in the sample; (e) inputting the value to a tank tool recipe control to cause any needed adjustment in concentration of HF to a predetermined range, either in the mixing tank or the wafer processing vessel; and (f) subjecting the wiring/interconnect of the semiconductor device to etching by the etchant composition to remove sidewall polymer, polymer rails and via residue without etching conductive materials during removal of sidewall polymer, polymer rails, and via residue.