Comparison of Dynamic Simulations with RBS Measurements of Low Energy Ion Implantation of Sb⁺ into SiO₂/Si Substrates

Abstract.

Antimony ions were implanted into SiO₂/Si substrates at energies of 30 and 50 keV at relatively low doses (max. 5×10¹⁵ ions cm⁻²). The behaviour of the implanted ions was simulated with a dynamic TRIM code, allowing treating alteration of the target in a dynamic mode, i.e. as a function of ion dose. For cases, where the projected range of the implant coincides with the interface, it has been observed that there is significant mixing between the SiO₂ layer and the Si substrate together with a constant value for the O/Si ratio except for a pronounced oxygen surface peak. Whereas in the cases, where the implant is far from the interface, the O/Si ratio shows characteristic oscillations together with the surface peak. For high doses, above about 10¹⁶ ions cm⁻², a gradual increase of the sputtering yield of SiO₂ is observed due to Sb incorporation in the substrate. The balance between the sputtering and swelling of the target is shown to be negative up to a fluence of 9.5×10¹⁵ ions cm⁻², although the total sputtering yield is more than 1. RBS (Rutherford Backscattering Spectrometry) measurements confirm the mixing at the interface in cases where the latter coincides with the projected range of the implanted ions.