Among the numerous solutions developed to improve the handling capability of superjunction power devices, the Deep Trench Termination (DT 2) is the most adapted thanks to its lower cost and size compared to other technologies using the multiple epitaxy technique, and an easier implementation in the fabrication process. This paper presents the optimization of the Deep Trench Termination by means of TCAD 2D and 3D-simulations allowing the realization of deep trench superjunction devices (diodes and MOS transistors) for 1200 V applications. The work is focused on the influence of the dielectric passivation layer thickness and the field plate length on the breakdown voltage of a DT-SJDiode. I. INTRODUCTION Today, the main IGBT competitor is the MOSFET. Indeed, the MOSFET exhibits many interesting properties for power applications: high switching speed, high input impedance and thermal stability. However, in high voltage range (600 V and above), conventional MOSFETs are limited by their very high specific on-resistance and, therefore, their high on-state voltage drop, which induces more on-state losses compared to bipolar devices. This on-resistance is inversely proportional to the doping concentration of the drift region, which must be low enough to sustain the off-state voltage: to find the best trade-off between these two parameters (specific on-resistance and breakdown voltage) is one of the major challenges in this voltage range. Recently, numerous researches have been done about the superjunction principle and about the way to realize it. Indeed, this principle allows to overcome the 'breakdown voltage/on-state resistance' trade-off. This technology was chosen in particular by Infineon for the realization of COOLMOS™ transistors [1] and by STMicroelectronics for the realization of MDMESH™ devices [2]. However, the manufacturing cost of this technology can be very high because the process requires a multiple epitaxy technique, resulting in a significant number of masks. The deep trench technology [3] is a lower cost alternative with only one epitaxial step. Like all power devices, it needs an adapted junction termination technique to reach the highest breakdown voltage. Several junction termination techniques are available [4]-[6] but our attention has stopped on the deep trench