REDUCING THE EFFECTS OF PLASMA PROXIMITY IN PLASMA IMMERSION ION-IMPLANTATION

Plasma Immersion Ion Implantation is shown to be a promising candidate for low-energy, high-dose ultra large-scale integration (ULSI) applic ations like ultra-shallow junction processing. Junctions shallower tha n 65 nm at a background concentration of 10(18) cm(-3) have been made with BF3 PIII (p-type) and PH3/H-2 PIII (n-type). Remaining concerns a bout PIII processing include impurity contamination, surface erosion, charging of thin oxide devices, and interaction with photoresist. Cont amination can be reduced through proper machine design and cleaning. S urface erosion is minimized by using higher frequency implantation: al though the erosion rate rises, the dose rate increases faster. Chargin g becomes severe at higher frequencies, so a moderate frequency (aroun d 10-20 kHz) is recommended to minimize both effects. The effect of PI II-photoresist interaction on devices is comparable to that seen with conventional implantation.