Etching platinum-containing thin film using protective cap layer

A method of forming a microelectronic device, comprising:

• providing a substrate having a top surface;
• forming a platinum-containing layer on the top surface of the substrate, the platinum-containing layer having a bottom surface on the top surface of the substrate and having a top surface located opposite from and facing away from the top surface of the substrate;
• forming a cap layer comprising one selected from a group consisting essentially of a cap layer that is primarily aluminum and a cap layer that is primarily copper on the top surface of the platinum-containing layer, wherein an interface between the cap layer and the platinum-containing layer at the top surface of the platinum-containing layer is free of platinum oxide;
• and
• removing the cap layer and at least a portion of the platinum-containing layer by a wet etch process, a same wet etchant of the wet etch process removing both the cap layer and the platinum containing layer, the cap layer having an etch rate at least twice the etch rate of the platinum containing layer in the same wet etchant, the wet etch process exposing the top surface of the substrate.