Tantalum carbide and nitride diffusion barriers for Cu metallisation

Abstract

The reactions in the Si/TaC/Cu and Si/Ta 2 N/Cu metallisation systems were investigated by x-ray diffraction, Rutherford backscattering, scanning electron microscope and the transmission electron microscopy. The results were then combined with the assessed ternary SiTa-C, Ta-C-Cu, Si-Ta-N and Ta-N-Cu phase diagrams. It was found that both barriers ultimately failed due to diffusion of Cu through the barrier and accompanied formation of Cu 3 Si at temperatures higher than 725 °C. However, in the TaC barriers the formation of amorphous TaO x layer with significant amounts of C took place at the TaC/Cu interface already at 600 °C. Similar behaviour at "low" temperatures was also noted in the Ta 2 N barriers.

Atom beam sputtered Mo2C films as a diffusion barrier for copper metallization

“…It has been observed that when Cu/Mo 2 C/Si structure is annealed at temperature 700 8C, a number of bright particles of varying sizes from 1 to 2 mm appeared. With the further annealing of structure at 800 8C, the size of these white particles reaches to 5-10 mm as compared to 20-30 mm in case of sputter deposited Cu/TaC/Si system [14]. These bright regions were characterized as MoSi 2 and Cu 3 Si using EDX elemental mapping technique.…”

“…In order to keep the advantages of scaling technology, the past decade has seen the tremendous efforts in terms of the developing new process technology, materials and their combinations [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Since the performance of the future IC technology will be limited by the resistance of the metal interconnects [8], copper metallization is emerging as the alternative to aluminum due to its low electrical resistivity (1.72 mV cm), high melting temperature (1084 8C), high electro-migration resistance and also high stress voiding resistance.…”

Copper diffusion in TaN-based thin layers

“…The obtained microstructure, which is not always reported in the literature, is greatly dependent on the process parameters. Moreover impurities, especially oxygen, may have a strong effect on kinetics also, as previously reported for Ta and TaC diffusion barriers by Laurila et al [3,17] and Clevenger et al [18]. No data have been reported for the thermal stability of TaN/Ta/ TaN barriers.…”

Characterization of contact resistance between electrode and TaNx thin‐film resistor prepared by reactive sputtering

“…Recently, an application other than as a resistor material is as the diffusion barrier layer of copper wiring in the routing technology of integrated circuits [3]. Many reports have discussed the deposition of the TaN x thin film, but most of these studies focused on the resistance of the thin film itself and reports related to the contact resistance with the electrode have not appeared.…”