THE PROCESS LIMITATION FOR FORMING TI SILICIDED SHALLOW JUNCTION BY BF(2)+ IMPLANTATION INTO THIN POLYCRYSTALLINE SI FILMS AND SUBSEQUENT TI SILICIDATION

Excellent shallow p+n junctions have been formed by implanting BF2+ io ns into thin polycrystalline Si films and subsequent annealing; these junctions which show a leakage of 1 nA/cm2 and a junction depth of abo ut 0.05 mum. An anomalous boron diffusion occurs when subsequent silic idation is carried out. Silicidation using 300-angstrom Ti just slight ly affected the junction profile. However, the junction is considerabl y deepened for 600-angstrom Ti silicidation, yielding a resulting dept h of about 0.11 mum. The large boron redistribution is attributed to t he point defects induced by silicidation. Hence, proper silicide thick ness should be chosen to retain the junction profile as well as to red uce the parasitic source/drain resistance.