A fixing structure for a door handle includes a grip portion, a first fixing portion connected to a first end of the grip portion and fixed to a side of a door, and a second fixing portion connected to a second end of the grip portion and fixed to the side of a door. In one embodiment, an oxygen-containing gas is flowed into a remote plasma region to produce oxygen-containing plasma effluents, and a carbon-containing gas is combined with the oxygen-containing plasma effluents in a substrate processing region which contains the substrate. An exterior bottom end of the sleeve has a castellated surface. Additionally, at least one of the seams includes a spacer positioned between portions of the one or more separator materials joined by the at least one seam.