Palladium activation on dc magnetron sputtered tantalum and tantalum nitrides (TaN x) for autocatalytic electroless copper deposition has been investigated with various nitrogen content by using X-ray diffraction, sheet resistance measurement, field emission scanning electron microscopy ͑FE-SEM͒, plan view transmission electron microscopy ͑TEM͒, and X-ray photoelectron spectroscopy ͑XPS͒. The addition of a small amount of nitrogen induced a phase transformation of as-deposited TaN x films. As the nitrogen flow rate was increased, the electrical resistivity of the as-deposited TaN x films initially decreased for nitrogen flow rate up to 10 standard cubic centimeters per minute ͑sccm͒ followed by an increase for a nitrogen flow rate above about 20 sccm. FE-SEM and plan view TEM analyses showed that the density of palladium nuclei increased with nitrogen content. In contrast, the grain size of TaN x films decreased with increasing nitrogen flow rate. XPS results of palladium-activated TaN x films showed that no chemical shift of metallic palladium peak was observed after the activation process.

This work proposes a new method toward improving dielectric barrier characteristics through low dielectric permittivity (k) amorphous silicon nitride films (SiNx) deposited by plasma enhanced atomic layer deposition (PEALD). The dielectric constants of the atomic layer deposition (ALD) SiNx films were in the range of 4.25–4.71 and were relatively lower than that of SiNx deposited by plasma enhanced chemical vapor deposition (PECVD). The dielectric constants of the PEALD SiNx films were nearly identical to the values for PECVD silicon carbon nitride films (SiCN). Although the ALD SiNx films were low-k, they exhibited similar levels of film stress as PECVD SiNx, and the density of ALD SiNx film was higher than that of PECVD SiCN films. The ability to suppress copper (Cu) diffusion through 10-nm thick SiNx dielectric barriers in silicon dioxide/barrier/Cu/tantalum nitride structures on Si substrates was evaluated via Auger electron spectroscopy analysis. Although PEALD SiNx films possessed low dielectric constants (<5), their barrier property to Cu diffusion was nearly equivalent to that of PECVD SiNx. The PECVD SiCN films also exhibited low dielectric constants but showed weak barrier property. Therefore, the low-k ALD SiNx reported herein could be used as a thin film thickness dielectric barrier layer in future advanced technologies.

No abstract

In this study, the effects of a thin Ru interlayer on the thermal and morphological stability of NiSi have been investigated. Ru and Ni thin films were deposited sequentially to form a Ni/Ru/Si bilayered structure, without breaking the vacuum, by remote plasma atomic layer deposition (RPALD) on a p-type Si wafer. After annealing at various temperatures, the thermal stabilities of the Ni/Ru/Si and Ni/Si structures were investigated by various analysis techniques. The results showed that the sheet resistance of the Ni/Ru/Si sample was consistently lower compared to the Ni/Si sample over the entire temperature range. Although both samples exhibited the formation of NiSi2 phases at an annealing temperature of 800 °C, as seen with glancing angle x-ray diffraction, the peaks of the Ni/Ru/Si sample were observed to have much weaker intensities than those obtained for the Ni/Si sample. Moreover, the NiSi film with a Ru interlayer exhibited a better interface and improved surface morphologies compared to the NiSi film without a Ru interlayer. These results show that the phase transformation of NiSi to NiSi2 was retarded and that the smooth NiSi/Si interface was retained due to the activation energy increment for NiSi2 nucleation that is caused by adding a Ru interlayer. Hence, it can be said that the Ru interlayer deposited by RPALD can be used to control the phase transformation and physical properties of nickel silicide phases.

No abstract