A switching device is disclosed, in particular an electrical circuit breaker, including a housing and a switching unit disposed inside the housing. The target wellbore includes a conductive member disposed within a portion of the target wellbore. After the silicon containing sacrificial layer has gettered the impurities from the high-k gate dielectric layer, the silicon containing sacrificial layer is removed, and a gate electrode is formed on the high-k gate dielectric layer. In this way, the connection tubes can be firmly attached to each other in a vertical or a horizontal position at contact surfaces between the top and bottom coupling members by use of fixing elements so that an excellent interlocking strength between the connection tubes can be ensured.