Ion beam and chemically assisted ion beam etching of InP with anisotropic and smooth surfaces

In this paper, we investigate ion beam etching (IBE) and chemically assiste d ion beam etching (CAIBE) of InP. While argon (Ar) alone is used for the I BE process, the CAME is carried out by using Ar/H-2/CH4. The realization of CAME in an Ar/H-2 atmosphere is also achieved for the first time. The evol ution of the surface roughness and morphology is presented comparatively by varying the acceleration voltage (V-acc), the discharge current (I-dis) an d the ion incidence angle. The etch rate of the InP structures is studied a s a function of I-dis and V-acc. The variation of the etch rate against the ion incidence angle is also investigated experimentally. A maximum etch ra te of 70 nm min(-1) is observed for an acceleration voltage of 2 kV and a d ischarge current of 45 mA at a 30 degrees ion incidence angle. It is also f ound that a drastic improvement of the surface roughness is observed for CA ME using Ar/H2 chemistry. In addition, the anisotropy of InP samples is als o presented for two different masks, Al2O3 and titanium (Ti) for the CAME m ode. The most anisotropic structure of 83 degrees is performed using the Ti mask. Finally, the etched surfaces are quantified using the atomic force m icroscopy technique where the lowest root-mean-square roughness of 4.3 nm i s found when using only Ar/H-2 gases.