The present disclosure is directed to structures and processing for three-dimensional transistor devices. In some approaches, a method may include providing a plurality of fin structures formed from a substrate, the plurality of fin structures disposed subjacent to a hard mask layer, and directing angled ions at the plurality of fin structures. The angled ions may form a non-zero angle of incidence with respect to a perpendicular to a plane of the substrate, wherein the angled ions etch the plurality of fin structures to form a stack of isolated nanowires within the plurality of fin structures. The method may further include removing the hard mask layer, and forming a stopping layer over the stack of isolated nanowires.