Smooth and anisotropic ion beam etching of InP with Ar/H2 chemistry

Abstract

Ion beam etching (IBE) and chemically assisted ion-beam etching (CAIBE) of InP wafers are studied. While Argon alone is used for the IBE process, the CAIBE is carried out by using Ar/H<SUB>2</SUB>CH<SUB>4</SUB>. The realization of CAIBE in Ar/H<SUB>2</SUB> atmosphere is also achieved for the first time. The evolution of the surface roughness and morphology is presented comparatively by varying acceleration voltage (V<SUB>acc</SUB>), discharge current (I<SUB>dis</SUB>) and ion incidence angle. A drastic improvement of the surface roughness is obtained for the CAIBE using Ar/H<SUB>2</SUB> chemistry. The etch rate of the InP structures is studied as a function of the I<SUB>dis</SUB> and the V<SUB>acc</SUB>. A maximum etch rate of 700 angstrom/min is observed for 1.75kV acceleration voltage and 45 mA discharge current at 30 degrees ion incidence angle. The variation of the etch rate against the ion incidence angle is investigated both theoretically and experimentally. A good agreement between those is observed. Finally, the anisotropy of InP samples is presented for two different masks; Al<SUB>2</SUB>O<SUB>3</SUB> and Titanium in the case of CAIBE mode. The most anisotropic structure of 83 degrees is performed by using the Ti mask.