The effects of nitrogen implantation into LDD region on sub-micron device characteristics

In this work, we investigate the characteristics of LDD nitrogen implanted MOSFET. NMOS devices were fabricated by 0.18 mu m CMOS technology with coba lt salicide. RSCE can be reduced and hot carrier reliability improved in NM OSFET by nitrogen implantation technique into LDD (NIL). It is believed tha t nitrogen suppresses the TED of channel boron by occupying boron diffusion site. Fortunately, nitrogen around the channel region strengthens the inte rface state of Si-SiO2, which provides a more improved hot carrier lifespan . However, it develops short channel effect by reducing effective channel l ength since nitrogen controls the boron's pileup to the surface. In additio n, the channel length margin characteristic is deteriorated with the degrad ation of transconductance. From these results, we can conclude that LDD nit rogen implantation technique has some trade-offs between the design margin characteristics and the hot carrier reliability in NMOSFET.