iii removing portions of the dielectric layer and the poly silicon layer outside the deep trench 111 resulting in the dielectric layer 112 and the poly silicon region 114 it should be noted that the dielectric layer 112 and the poly silicon region 114 can be collectively referred to as a deep trench isolation region 112 114 next with reference to fig1 c in one embodiment n u2212 regions 120 120 a and 120 b are formed in the p substrate 110 the n u2212 regions 120 120 a and 120 b can comprise n type dopants e g arsenic atoms the n u2212 regions 120 120 a and 120 b can be formed by i forming a photoresist layer not shown on top of the structure 100 of fig1 b ii patterning the photoresist layer and iii ion implanting n type dopants by an ion implantation process into the semiconductor structure 100 with the patterned photoresist layer as a blocking mask resulting in the n u2212 regions 120 120 a and 120 b after that the patterned photoresist layer is removed resulting in the structure 100 of fig1 c as a result of the n u2212 region 120 and the n u2212 regions 120 a and 120 b being formed by the same ion implantation process a depth 121 of the n u2212 region 120 and a depth 121.