Structural damage produced in InP(100) surfaces by plasma-employing deposition techniques

Abstract

In previous work we demonstrated that rf diode sputter deposition of an oxide onto a clean InP(100) surface produced structural damage and/or interfacial mixing at any sputtering power. In contrast, plasma-enhanced chemical vapor deposition of SiO2 at 13.56 MHz at any plasma power was damage-free and gave an abrupt interface. Structurally damage-free means that the large majority of the surface and near-surface In and P atoms are not displaced from their lattice sites; this does not preclude the presence of electrical or optical modification. In this work, again using Rutherford backscattering under channeling conditions, we have investigated the interface between InP and a deposited dielectric or metal for various other types of plasma and sputter deposition. Dose and/or energy of species incident on the InP surface during the initial stage of deposition has been varied over the spectrum intermediate to the relative extremes of the two previously studied cases. The general conclusions are as follows. Plasma deposition is structurally damage-free, even at low frequency and at a low deposition rate to plasma power ratio, as for SiNx. Sputter deposition, however, is always damaging, even when there are no energetic negative ions incident on the InP substrate, or even when the InP substrate is remote from the plasma, as in ion beam sputter deposition. Use of a light sputtering gas (He) in place of Ar increases the magnitude of damage. Annealing at 450 °C can reduce but not remove the damage.