Nitridation of Silicon and Oxidized‐Silicon

Abstract

The nitridation of silicon and oxidized‐silicon has been studied. The nitrided films were prepared at 900°–1150°C under ammonia partial pressures of 10−3 to 5 kg/cm2 in nitrogen and were analyzed by ellipsometry and Auger electron spectroscopy. For films formed by nitridation of silicon, we found that the growth kinetics and properties such as chemical composition, etching rate, and oxidation resistance were independent of the ammonia partial pressure. The nitridation of silicon can be explained by a modified Ritchie‐Hunt theory, which assumes that a very slow surface reaction at the ammonia‐nitride interface is the rate‐determining factor, using the logarithmic rate law. According to this modified Ritchie‐Hunt theory, the nitridation of silicon proceeds mainly by cation migration under a constant electric field. On the other hand, it was found that the nitridation of oxidized‐silicon depended strongly on the ammonia parital pressure. This dependence may be caused by diffusion of ammonia or its derivatives through the oxide. The conversion of silicon dioxide to silicon oxynitride occurred throughout the oxide.

Selective Oxidation Using Ultrathin Nitrogen‐Rich Silicon Surface Layers Grown by Rapid Thermal Processing

“…4 can be used to describe the characteristic time for this process. The adjusted curve is [2] where A(T) = A(Tnit, Tox)-In this case, A(1200 ~ ll00~ = l13A. And, the characteristic time is 9 = 2.882s.…”

“…For the low pressures used, typically 0.1-1.0 torr, diffusion coefficients are three to four orders of magnitude larger than at atmospheric pressure. The absence of a corresponding increase in growth rate eliminates some mass transport and depletion effects that are common to atmospheric systems (1)(2)(3)(4), and so allows high wafer density without compromising the uniformity of film growth. High wafer density is usually achieved by stacking the wafers coaxially in a wafer boat within a tubular reactor, shown in Fig.…”

“…These layers are usually prepared by direct thermal reaction of silicon with nitrogen (1) or ammonia (2,8). Ion implantation of nitrogen into silicon for the purpose of oxide growth inhibition has also been reported (4,5).…”

Permanent reduction of dissipation in nanomechanical Si resonators by chemical surface protection

“…The three most successful approaches are presented in figure 3 and include thermal nitridation [32] and organic monolayer deposition by liquid-phase [21] and gas-phase hydrosilylation [33]. Additional reactions tested include two-step alkylation/ amination, spontaneous grafting of diazonium salt, coating of diffusion barrier layers by atomic-layer deposition and by electron beam evaporation, and a simultaneous exposure to …”

Characterisation of ultrathin dielectric films with ion beams

“…In the early studies it was thought 1,-28] that the growth mechanism of SisN4 films may be similar to that of SiO2 films: the nitriding species (nitrogenous radicals) diffuse across the growing nitride film to react with silicon at the nitride-silicon interface. Based on improved data for growth kinetics, another growth mechanism was proposed [29,30], in which the Si atoms diffuse from the Si substrate across the growing Si3N 4 film to react with NHs at the nitride surface. This scenario was consistent with the observation that the nitridation kinetics depend weakly on the NH3 pressure.…”