Selective Si and Be implantation in GaAs using a 100 kV mass-separating focused ion beam system with an Au–Si–Be liquid metal ion source

Submicron Si and Be ion beams have been implanted into GaAs using a 100 kV maskless ion implantation system with a liquid metal ion source which is capable of emitting double ion species (Si++ and Be++). Both ion beams are implanted at 160 keV with the dose of 1013 to 1014 cm−2. The feasibility of the focusing column was demonstrated by forming the submicron width of line patterns of alternative Si and Be doping in GaAs including a pn junction array. The linewidth of the ion implanted area has been evaluated by SEM, after selective etching of the annealed sample. It has been found that high dose implantation results in considerable lateral impurity spread of more than 1 μm even with the focused ion beams with a diameter of 0.1 μm. However, submicron width implantation turns out to be possible with relatively low doses or with shallow dopings.