PELOX integrated PBL

Polysilicon buffered LOCOS (PBL) has been widely utilized for advanced isolation applications as moderately low lateral oxide encroachment may be achieved without defect formation. Unfortunately, PBL does not exhibit sufficient field oxide recess to support aggressive device scaling without introduction of processes which are difficult to control. Recently, polysilicon encapsulated local oxidation (PELOX) has been proposed as an easily scaled isolation technique that exhibits LOCOS equivalent recess. The integration of PELOX into an existing PBL 1 Mb DRAM baseline process is described. PELOX integrated PBL (PIPBL) is demonstrated to enhance final field oxide recess without increasing encroachment. The improved final field oxide recess is shown to provide increased process margin as evidenced by superior probe yield.