New SOI structures for intelligent power ICs with vertical double-diffused MOS output devices

Intelligent power ICs with vertical double-diffused MOS (VDMOS) output devices are used for solenoid controlled applications. Many structures have been proposed for these power ICs. We have developed poly-Si sandwiched bonded (PSB) structures which use a Sb doped poly-Si and crystal-Si bonding technique. However these PSB structures have a high fabrication cost, because the fabrication process includes Sb diffusion into poly-Si layers. In this paper, we first propose an improved fabrication process of PSB structures without Sb diffusion into poly-Si layers. Second, we propose a new SOI structure with gaps fabricated by a wafer direct bonding technique. Both structures enable us to obtain low-cost intelligent power ICs with VDMOS.