In various embodiments, semiconductor structures and methods to manufacture these structures are disclosed. In one embodiment, a semiconductor structure having a silicon-on-insulator (SOI) substrate and a dielectric region is disclosed. The dielectric region is adjacent to the active layer of the SOI substrate and the dielectric region includes a portion of a buried oxide (BOX) layer of the SOI substrate. At least a portion of the dielectric region extends from a surface of the active layer of the SOI substrate to a depth of at least about three microns or greater below the surface of the active layer. Other embodiments are described and claimed.