A new semi-insulation structure in which one isolated island is connected to the substrate was proposed.Based on this semi-insulation structure,an advanced BCD technology which can integrate a vertical device without extra internal interconnection structure was presented.The manufacturing of the new semi-insulation structure employed multi-epitaxy and selectively multi-doping.Isolated islands are insulated with the substrate by reverse-biased PN junctions.Adjacent isolated islands are insulated by isolation wall or deep dielectric trenches.The proposed semi-insulation structure and devices fixed in it were simulated through two-dimensional numerical computer simulators.Based on the new BCD technology,a smart power integrated circuit was designed and fabricated.The simulated and tested results of Vertical DMOS,MOSFETs,BJTs,resistors and diodes indicated that the proposed semi-insulation structure is reasonable and the advanced BCD technology is validated. A new semi-insulation structure in which one isolated island is connected to the substrate was proposed. Based on this semi-insulation structure, an advanced BCD technology which can integrate a vertical device without extra internal interconnection structure was presented. The manufacturing of the new semi-insulation structure employed multi-epitaxy and selectively multi-doping. Isolated islands are insulated with the substrate by reverse-biased PN junctions .Adjacent isolated islands are insulated by isolation wall or deep dielectric trenches. proposed semi-insulation structure and devices fixed in it were simulated through two-dimensional numerical computer simulators. Based on the new BCD technology, a smart power integrated circuit was designed and fabricated. The simulated and tested results of Vertical DMOS, MOSFETs, BJTs, resistors and diodes indicated that the proposed semi -insulation structure is reasonable and the advanced BCD technology is validated.