Abstract
In recent years, the power device research is widely proposed when the energy issues become more important. In many power device component the super junction structure power device is widely discussed because this device can reduce the specific on-resistance of the power MOSFETs to below the Si-Limit. Several methods of fabricating super junction in power MOSFETs has been proposed, such as, multi-step epitaxial growth and trench filling technique. The trench filling method is generally easier and less costly than the epitaxial growth. However, it is very difficult to realize high-aspect-ratio P/N pillars though conventional trench filling technique. In this paper, we propose the multi-step trenching/filling technique to implement high-aspect-ratio super junction structure. The proposed the multi-trench process can not only effectively alleviate the deep trench filling problem, but also provide better process margin in the implementation of super junction power devices. This multi-trench process allows additional design freedom in the number of trench layers and doping concentration in each layer, which can lead to better breakdown performance in both the main and termination regions.