Maskless ion implantation technology for III–V compound semiconductors

Abstract

We describe systematic research on maskless ion implantation technology for III–V compound semiconductors using a 100 kV focused ion beam system that has an Au-Si-Be liquid metal ion source. This ion source emits both p- and n-type ion beams from one tip. Finely focused Be (p) or Si (n) ion beams smaller than 0.1 μm can be implanted freely into the designed patterns in the substrates by switching the electric field of the E × B mass filter. The lateral spread of an impurity profile implanted by a 0.1 μm focused ion beam can be limited to within 0.5 μm. Raman spectra from Be- and Si-implanted GaAs indicate that the higher current density of the focused ion beam results in less implantation-induced damage than that of the unfocused beam by a conventional implanter. According to Hall effect and PL measurements, the implanted layers annealed at high temperatures have shown comparable or better electrical and optical characteristics than those with unfocused beams. Finally, simple optical device fabrication and contamination-free processes, typical applications of maskless ion implantation technology, have been demonstrated.