Phenomenological model for local overheating and etching of multilayer graphene. Schematic model representing the possible origin of local overheating and etching of outermost graphene layers grown on Cu films. The heat provided by the focused laser beam is dissipated through in-plane (horizontal arrows) and out-of-plane (vertical arrows) channels. Though the in-plane channel is dominant in graphene, the finite size of outer layers makes out-of-plane dissipation significant and reduces the in-plane contribution, thus causing local overheating and subsequent etching of the layers. The innermost layer is instead prevented from etching by the presence of the Cu substrate acting as heat sink.