Fin fabrication process with dual shallow trench isolation and tunable inner and outer fin profile

A self-aligned active region block mask is used to pattern and define a plurality of semiconductor fins as well as attendant shallow trench isolation (STI) structures. The block mask, a portion of which comprises a patterned fin hard mask, permits decoupling of inner and outer fin etch processes, as well as independent optimization of inner fin and outer fin dielectric properties. The fin-forming method also forestalls the creation of isolated, free-standing fins, which decreases the likelihood of mechanical damage to the fins during processing.