Ion beam and chemically assisted ion beam etching ofInP with anisotropic and smooth surfaces

Abstract

In this paper, we investigate ion beam etching (IBE) andchemically assisted ion beam etching (CAIBE) of InP. While argon (Ar)alone is used for the IBE process, the CAIBE is carried out by usingAr/H2/CH4. The realization of CAIBE in an Ar/H2atmosphere is also achieved for the first time. The evolution of thesurface roughness and morphology is presented comparatively byvarying the acceleration voltage (Vacc), the dischargecurrent (Idis) and the ion incidence angle. The etch rate ofthe InP structures is studied as a function of Idis andVacc. The variation of the etch rate against the ionincidence angle is also investigated experimentally. A maximum etchrate of 70 nm min-1 is observed for an acceleration voltage of2 kV and a discharge current of 45 mA at a 30° ionincidence angle. It is also found that a drastic improvement of thesurface roughness is observed for CAIBE using Ar/H2 chemistry.In addition, the anisotropy of InP samples is also presented for twodifferent masks, Al2O3 and titanium (Ti) for the CAIBEmode. The most anisotropic structure of 83° is performedusing the Ti mask. Finally, the etched surfaces are quantified usingthe atomic force microscopy technique where the lowestroot-mean-square roughness of 4.3 nm is found when using onlyAr/H2 gases.