Suppression of boron penetration through thin gate oxides by nitrogen implantation into the gate electrode of PMOS devices

PMOS devices with different amounts of nitrogen implanted into the gate ele ctrode before doping with BF2 implantation and implant anneal were manufact ured, The thicknesses of the gate oxides grown in dry oxygen by RTP were 4. 1 down to 2.8 nm, The implant anneal was also performed by RTP. The influen ce of the nitrogen on the penetration of boron ions through the ultra-thin gate oxides into the channel region was investigated by electrical and SIMS measurements. Boron was effectively prevented from diffusion by high nitro gen concentrations at the polysilicon/ gate oxide interface without degradi ng the reliability, In return, increased sheet resistivities and gate deple tion have to be taken into account by high nitrogen concentrations within t he polysilicon gate electrode, (C) 2000 Elsevier Science Ltd. All rights re served.