Wayne J. Ray

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>>

The effect of biased spacers on LDD MOSFET behavior

The concept of using LDD spacers that are independently biased with respect to the gate electrode is presented. It is shown that the lateral electric field is strongly influenced by the drain polysilicon spacer potential. Depending on the N/sup -/ dose, the peak substrate currents can be either enhanced or reduced by shorting the drain polysilicon spacer to the drain potential. Short-channel LDD MOSFETs have been fabricated with polysilicon LDD spacers shorted to the source and drain electrodes by titanium silicide.<<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>>