A method of forming an SOI structure which includes providing a semiconductor on insulator (SOI) substrate having an SOI layer, an intermediate buried oxide (BOX) layer and a bottom substrate; patterning the SOI layer to form first and second openings in the SOI layer; extending the first openings into the bottom substrate; enlarging the first openings within the bottom substrate; filling the first and second openings with an insulator material to form deep trench isolations (DTIs) from the first openings and shallow trench isolations (STIs) from the second openings; implanting in the bottom substrate between the DTIs to form wells; and forming semiconductor devices in the SOI layer between the DTIs with each semiconductor device being separated from an adjacent semiconductor device by an STI.