Scott S. Roth

Polysilicon encapsulated local oxidation

Polysilicon encapsulated local oxidation (PELOX) is proposed as an effective isolation technique that satisfied advanced device requirements without any difficult-to-control structures or processes. Simple modifications to a standard local oxidation of silicon (LOCOS) process flow minimize encroachment without introducing defects. These modifications include an HF dip after nitride patterning to form a cavity self-aligned to the nitride edge, reoxidation of exposed silicon, and polysilicon deposition to fill the cavity. Physical (scanning electron micrographs) and electrical (gate oxide quality, diode integrity, and W/sub eff/) data which indicate that cavity reoxidation is critical to obtaining significant birds beak reduction without defect introduction are presented.<<ETX>>

A new toroidal TFT structure for future generation SRAMs

A new toroidal TFT structure has been developed for future generation SRAM products. This new TFT provides excellent device performance at scaled power supply voltages and offers significant savings in bitcell area.<<ETX>>

PELOX integrated PBL

Polysilicon buffered LOCOS (PBL) does not exhibit sufficient field oxide recess to support aggressive device scaling without the 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. >

Recessed polysilicon encapsulated local oxidation

Local oxidation of silicon (LOCOS) is the most commonly used isolation technology in silicon integrated circuits. The inherently large field oxide encroachment associated with LOCOS severely limits scalability. Recessed polysilicon encapsulated local oxidation (recessed PELOX) is demonstrated to achieve both low encroachment and increased field oxide recess. These benefits are obtained without sacrificing process simplicity or defectivity as evidenced by excellent gate oxide and diode quality.<<ETX>>