PURPOSE: A Cr-etchant formulation with high thermal stability is provided to prevent residue generation during etching process. CONSTITUTION: The Cr-etchant formulation comprises 5 to 30 wt.% of cerium ammonium nitrate (Ce-(NH4)2-(NO3)6); 3 to 30 wt.% of nitric acid (HNO3); 0.5 to 30 wt.% of ammonium nitrate (NH4NO3) and a balance of water. In this formulation, 3 to 30 wt.% of nitric acid (HNO3) can be replaced by the same amount of perchloric acid.