Experimental studies of the etching of platinum thin films have been performed with a photoresist mask in an inductively coupled plasma. The physical bombardment by incident Ar ions dominates the platinum etch rate. In order to minimize the formation of sidewall deposition, the effects of the addition of various halogen gases to Ar plasma were evaluated. For the blanket platinum samples etched in Ar/CF4 plasmas, the existence of Pt-F compounds was found by using secondary ion mass spectrometry. By adding CF4 in Ar/Cl2 gas plasmas, an increase of etch rate for platinum films was observed. This suggests that the addition of CF4 to the Ar/Cl2 gas mixture could enhance the reaction between platinum and fluorine on the platinum surface by providing more fluorine radicals and ions. The respective etch contribution provided by the three components (Ar, CF4 and Cl2) has been investigated. A fence-free platinum electrode can be obtained under an optimum Ar/CF4/Cl2 gas mixture ratio, resulting in an etch rate of 48 nm/min.