High-fluence Co implantation in Si, SiO2/Si and Si3N4/Si Part I: formationof thin silicide surface films

In order to obtain thin CoSi2 surface layers, Si(1 1 1) and Si(1 0 0), cove red by SiO2 or Si3N4 With different thickness, have been implanted by Co to normal fluences from 1x10(16) to 2.6x10(18) ions cm(-2). The Co ions were produced by a high beam current MEtal Vapour Vacuum Are (MEVVA) ion implant ation system with 40 kV acceleration voltage. Time-of-Flight Energy Elastic Recoil Detection (ToF-E ERD) was used to determine the incorporation of Co in the coating materials and silicon substrates. The phase formation and e lectrical characterisation have been studied by X-ray diffraction (XRD) and a four-point probe system. The results reveal that the oxide and nitride l ayers are uniformly eroded and no significant N or O transport into the bul k Si is observed. After implantation, a thin surface silicide layer (simila r to 80 nm) with both a smooth surface topography and sharp interface could be obtained. The optimum Co normal fluence for producing a flat silicide l ayer depends on the surface film material and its thickness. (C) 1999 Elsev ier Science B.V. All rights reserved.