Erosion of tungsten-doped amorphous carbon films in oxygen plasma

► Tungsten-doped amorphous carbon films were eroded in oxygen plasmas. ► Initial C removal rate decreases with increasing W concentration. ► Erosion rate decreases with plasma exposure duration due to W accumulation at the surface. ► W-rich layer at the surface is porous WO3. ► W erosion only if ion energy higher than threshold for physical sputtering.