The Effect of Depth, AIR Gap Width and ION Implant on Deep Trench Isolation for BCD Technology

The voltage capability requested to power devices typically spans from 5 V up to 100 V mainly for automotive applications. Owning to the better isolation performance and device integration, deep trench isolation (DTI) is widely used in medium and high voltage grade BCD devices as the substitute for junction isolation. In this study, a combination of simulation and experimental research was employed in systematic investigation of trench depth, air gap width and implant to the device performance. We found that the depth of DTI needs to be at least 24 um for BCD devices with voltage capabilities greater than 100V. The existence of air gap inside DTI and ion implant at DTI bottom can also substantially improve the breaking voltage and prevent leakage. This work presents an optimized DTI structure which can addressed to high voltage (over 100 V) BCD technology platform.