A new trench isolation technology as a replacement of LOCOS

A new trench isolation technology that is replaceable to LOCOS and is suitable for submicron VLSIs is presented. The technology is featured with bird´s beak free, planar surface, low defect generation, and adaptable to any isolation width from submicron to very large dimensions. The key process steps consist of filling the trench with polysilicon to a half of the trench depth by utilizing photoresist etch back, and subsequent full oxidization of the recessed polysilicon to fill the trench by the oxide. Device characteristics examined experimentally are equivalent to those of LOCCS isolated devices. The feasibility of this technology has been verified successfully by fabricating a 64K bit DRAM.