Swelling of the Solid Surface induced by MeV Ion Implantation

Abstract

Surface swelling of sintered silicon-nitride, sintered alumina and single crystal sapphire implanted with 0.7-3 MeV N⁺. Si⁺ and Ni⁺ ions to 5×10¹³-5×10¹⁷ ions/cm², were evaluated by measuring the step height of the implanted region with a surface profile meter. The swelling became measurable when the dose exceeded 1×10¹⁴-1×10¹⁵ ions/cm², increased with increasing dose, then saturated. In the case of implantation of heavier ions or for low temperature implantation, the dose required to induce a measurable swelling is lower and the step height for saturation is higher. The step height profile versus dose for silicon-nitride is not similar to the one for alumina or sapphire. The swelling of the single crystal is larger than that of the sintered material, generally. After the annealing (1200°C, 1 hr in vacuum), the swelling is reduced about 30%. This phenomenon of surface swelling can be simulated semi-qualitatively by Monte Carlo calculation.