High-fluence Co implantation in Si, SiO 2/Si and Si 3N 4/Si : Part II: sputtering yield transients, the approach to high-fluence equilibrium

Abstract

The partial sputtering yields of different species from silicon dioxide/Si and silicon nitride/Si during high-fluence keV Co Metal Vapour Vacuum Arc (MEVVA) irradiation are of importance for both silicide formation and interpretation of sputter profiling. Three sets of samples, nitride/Si(1 0 0), oxide/Si(1 0 0) and oxide/Si(1 1 1), have been bombarded to different normal fluences, Θ, from 1 × 10 16 to 2.6 × 10 18 ions cm −2. The partial sputtering yields for N and Si in the thick nitride films are ∼1.0 and ∼0.65, respectively, which indicates that the relative sputtering ratio of N/Si is ∼1.5. The partial sputtering yields for O and Si of oxide/Si(1 0 0) samples are determined as ∼1.0 and ∼0.3, respectively. Although the O and Si sputtering yields from oxide/Si(1 1 1) samples are ∼15% higher, the average sputtering ratio of O/Si is ∼3.4, the same for both sets of oxide/Si samples. As expected, the partial sputtering yield of Co, Y Co( Θ), is small for low fluence implantation and increases with increasing Co fluence. At a normal fluence of ∼5 × 10 17 ions cm −2, Y Co( Θ) reaches the high fluence quasi-equilibrium limit, the value is very close to unity. The sputtering yield of Co reduces slightly at even higher fluences, which is associated with erosion of the sample surface.