SUBMICRON COSI2 STRUCTURES FABRICATED BY FOCUSED ION-BEAM IMPLANTATION AND LOCAL FLASH LAMP MELTING

A new way to fabricate submicron CoSi2 structures on Si wafers is pres ented. The method consists of a combination of focused ion beam (FIB) implantation of Co+ ions and subsequent flash lamp irradiation. With o ur FIB equipment IMSA-100 one- and two-dimensional structures were imp lanted by writing with a 35 keV Co+ beam which was focused to a spot d iameter of 200 nm. However, for the proposed method the spot size is n ot the crucial dimension because the final structure size is controlle d by a local melting and recrystallization process in the implanted re gions. Here the structure size is determined by the amount of implante d atoms which can be concentrated by the local melting process into th e submicron CoSi, structures. The local melting is caused by heteronuc leation at the Si wafer surface during the short period of superheatin g, which is obtained by intense flash lamp irradiation of 3 or 20 ms d uration. Disintegration of implanted CoSi2 wires by precipitate format ion during thermal annealing, which was reported by Liddle et al. (Mat er. Res. Sec. Symp. Proc. 279 (1993) 881), can be avoided by this meth od. The CoSi2 structures were analysed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), Dots and wires of a bout 200 nm diameter and width, respectively, have been fabricated dur ing these first experiments, whilst smaller dimensions seem to be poss ible in future.