Etching of platinum thin films in an inductively coupled plasma

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.