Alternative Approach for Substrate Connection Using Deep Trench Isolated Pockets

Authors propose an alternative approach for deep substrate connection through buried layer using existing features in the fabrication process flow with simple and completely modular process integration. This is done by creating isolated conductive paths from the wafer surface to the substrate inside isolated pockets. By doing so, authors eliminate the need to connect directly from the backside of the wafer to the substrate and avoid added cost, as well as, the limitations of additional assembly process. In this approach, authors create isolated small pockets with Deep Trench Isolation (DTI) and add an implant to counter dope the buried layer inside these pockets. Technology Computer Aided Design (TCAD) is used to optimize the counter doping implant with consideration to the buried layer doping profile and the thermal drive of the entire process. Blind alignment is used for the new implant photo and is characterized to assure sufficient process margin.