Electrical properties of thin silicon oxides grown at room temperature by ion beam sputtering technique

Abstract

Metal-oxide-semiconductor capacitors with 15 nm of silicon oxide deposited by ion beam sputtering on Si substrates were analyzed using current–voltage and capacitance–voltage measurements. A large Fowler–Nordheim conduction zone between a threshold field of 5 MV·cm⁻¹ and a breakdown field of 12.5 MV·cm⁻¹ was established. Hysteresis measurements led to conclude that a few amount of charge is stored in the bulk of the dielectric. Interface trap density was found to be very close to that of thermally grown Si oxide with a midgap value of 3.3 × 10¹⁰ cm⁻²·eV⁻¹. Fowler–Nordheim injections using a constant current density were used to study the build-up of trapped charge in the bulk oxide. Hence, the normalized centroid of the trapped charge distribution has been located close to the metal electrode. Only one trap was extracted from the simulation of experimental data with a saturated trap density among the lowest reported for Si/SiO₂ systems of N_T = 1.85 × 10¹² cm⁻² and a capture cross section σ = 2.9 × 10⁻¹⁶ cm². We demonstrated that a thin and reliable gate oxide with a high electrical quality can be achieved on Si by ion beam sputtering deposition at room temperature. Such an oxide takes its place in technologies where a low thermal budget is required e.g. system-on-panel technology.