The topography of sputtered semiconductors

Abstract

The surfaces of semiconductor single crystals were observed using a scanning electron microscope after bombardment at normal incidence at room temperature with doses between 0.5 × 10¹⁸ and 3 × 10¹⁸ of 40 keV argon ions/cm². The usual topography of the sputtered surface and the perturbing effects of dirt and contamination are reported, and observations of the variation of topography with dose are reported for GaAs. An explanation for the features observed is discussed with particular reference to current models of cone formation and secondary processes such as flux enhancement at the foot of steep slopes. The behaviour of Si, Ge, GaAs and InP was consistent with an amorphous surface. In the case of CdTe, CdS and GaP it appeared that the crystal structure was retained resulting in a topography of the sputtered surface that is sensitive to orientation. InSb appears to undergo a chemical change during ion bombardment.