A capacitive pressure sensor comprises a pair of conductive plates surrounding a compressible dielectric to form a capacitor. An electric motor has a stator within the motor compartment and a rotor within the stator. A tapered portion 7 is formed on the outside of the split shape sites 4E and 4F, and an end portion of the tapered portion 7 joins an engagement portion 8 that is formed in a protruding manner in the lateral direction of the inserting end portion 4C. An organosilicate glass dielectric film is patterned to form vias and trenches by subjecting it to an etchant or ashing reagent in such a way as to remove at least a portion of previously existing carbon containing moieties and reduce hydrophobicity of said organosilicate glass dielectric film.