an soi structure including a semiconductor on insulator substrate including a top silicon layer , an intermediate buried oxide layer and a bottom substrate ; at least two wells in the bottom substrate ; a deep trench isolation separating the two wells , the dti having a top portion extending through the box layer and top silicon layer and a bottom portion within the bottom substrate wherein the bottom portion has a width that is larger than a width of the top portion ; and at least two semiconductor devices in the silicon layer located over one of the wells , the at least two semiconductor devices being separated by a shallow trench isolation within the top silicon layer .