Spare cells are inserted in a region of an integrated circuit design based on a logic complexity of the region. In an etching step, at least a part of an absorption layer of an EUVL mask is etched by allowing a charged particle to irradiate the absorption layer under feed of a halogenated xenon gas. A flexible credit-based MAC protocol along with an admission algorithm enhance the network throughput capacity. Related methods of forming semiconductor devices are also provided. The structure has an axis of symmetry passing through the antenna feed connection. A tread reinforcing layer 12 formed from a thermoplastic resin or a thermoplastic elastomer composition including a blend of a thermoplastic resin component and an elastomer component is provided on an inner side of a tread portion 1.